Technics su 800 u technical specifications. Technics SU-A800DM2 Operating Instructions. About Sergey Begaikin

By chance I became the proud owner of a Technics SU-C800U preamplifier. I bought it at Molotok (auction) for 1850 rubles. During the bidding process, I repeatedly communicated with my friend (a radio engineer) about possible malfunctions. According to a friend, there is nothing to burn in pre-amplifiers (hereinafter referred to as pre-amplifiers), since low-current circuits very rarely damage anything. The seller did not give any guarantees in advance. The only thing that gave me some confidence that this item was intact was that the seller resold various radio equipment purchased in Germany. And if he indicated that the device had not been opened, it was so. An additional 400 rubles were spent on delivery. Less than 2 weeks passed before the product was delivered to me by mail.

An external examination showed that the seller was right when he indicated that there were small scratches on the top of the case. No other deficiencies were found. So let's move on to the preamplifier itself. In the original, it is powered from the final amplifier via a cable, the connectors of which are very reminiscent of S-video.

As a result of such a schematic construction, preamplifier has limited use, since it is not possible to use a pre-amplifier without a final amplifier, unless a power supply is built into it. It is possible that this article will help someone purchase a pre-amplifier and use it autonomously without a final amplifier, the price of which is significant. So, let's move on to our rams and in the preamplifier, unscrew the top cover and carefully remove it. Attention! We don't do ANYTHING else with the front.

Matsushita Electric engineers did everything to ensure that it could be upgraded without any problems. Upon careful examination of the board, control flags are found on it (there are 5 of them on the board), next to them on the board it is indicated what voltage should be on them. This is where external power needs to be supplied (soldered, already soldered in the photo).

To operate the device, a bipolar power supply of 15 volts and 10 volts alternating voltage is required. AC voltage is required to turn on the power relay and drive the volume control motor. All that remains is to find a suitable power supply that would fully suit the parameters and dimensions (the height of the transformer should not be higher than 5 cm). Those who are familiar with a soldering iron, of course, can easily make a power supply on their own, so in the future this article is for those who, like me, have had a soldering iron for a long time.

When designing the Technics SU-C800U pre-amplifier, Matsushita Electric engineers worked closely with engineers from the Riga Radio Plant named after A.S. Popov, who at that time were designing a promising model of the Soviet cassette tape recorder “Radiotekhnika”, otherwise explaining that the power supply from the tape recorder “ Radiotekhnika MP-7301 stereo (analogous to Radiotekhnika MP-201) is ideal for the Technics SU-C800U preamplifier.

I purchased this tape recorder with a broken kinematics for 100 rubles.

We open the tape recorder. We disconnect the cables from the boards connecting to the power supply. We unscrew the 4 bolts and disconnect the power supply along with the chassis on which the transformer is mounted from the base of the tape recorder.

We don't need the tape recorder anymore, so we put it away. We remove the protective casing of the transformer and cut off the upper part with metal scissors so that the casing remains about 3.5 cm in height. I replaced all the existing capacitors on the power supply board with imported capacitors of higher capacity. Next, we check using the diagram and the board: whether all the parts are on the board (mine was missing 3 diodes) and whether all the wires from the transformer are connected correctly. We unscrew the transistor radiators from the board, unsolder the transistors together with the radiators, cut off the radiators, leave about 2.5-3 cm, and check the transistors for leaks.

If everything is fine, we install everything in place.

Turn on the power supply without load and check the power. I set the construction resistors to 14.5 volts in my power supply. Then it’s a matter of imagination on how to secure the transformer and power supply board in the available space.

I separated the board from the base on which the transformer is mounted. I cut the base and secured the base along with the transformer to the pre chassis.

Installed the cut-off protective cover. The power supply board has 4 bolts, with insulators on the bottom, also secured to the chassis.

Now we solder the wires. We take pins 6 and 7 directly from the transformer AC voltage 10V and solder to the flags on the pre board, where AC10V is indicated.

From the power supply board it is indicated:
solder point No. 4 to the pre +15V;
point No. 3 is soldered to the pre-15V.

point No. 2 - ground, connected to the ground on the circuit board and connected to the circuit board chassis with a separate wire; The points are indicated for the board of the Radiotekhnika 7301-stereo tape recorder; for the Radiotekhnika MP-201, others are possible

We preliminarily measure all voltages with a measuring device.

After all the joining and securing it looked like this.

Close the lid and tighten the bolts. That's all. A beautiful preamplifier ready to go. Enjoy listening to music.

Another retro tour, another components and another audition. This time, Oldie pleased his teammates with the luxurious Optonika SM-3636HB integrated unit, the rare and extremely interesting Audio Visual Amplifier Sansui AV-7000 and the two-unit, top-of-the-line Technics A800S Reference.
All amplifiers are from famous

manufacturers, Made in Japan, solid weight and exorbitant characteristics. And in all three devices the preliminary and final paths are separated. Technix is ​​basically a two-block unit, and Sansui and Optonics have connecting jumpers.
The audition promises to be very interesting. In addition to the listed components, today's test includes: Super Audio CD Player Denon 3910, Technics SL-1500 Turntable, Sumiko Black Pearl stylus. Acoustics Electronics 25AC033, Radiotehnika S-90D, Quadral Phonologue Fortun, NewArtVinyl and Monster Cable thx interconnects. CD: Vladimir Kuzmin “Rocker”, 2va Samoleta “Ka Ra Bas”, Marcus Miller “Silver Rain”, Eric Bordon “My Secret Life”. Vinyl: Eric Bordon “My Secret Life”, Pfil Collins “No Jacket Required”.
Let's get started! Sansui AV-7000. An extremely rare device, and in our country - almost a single one. The previous owner brought the amplifier from Japan in 1991, paying $1,200 for it. I sat at the computer for two hours trying to dig up some reviews on it. Silence... Except for the characteristics - nothing.
So! Manufactured by Sansui Electric Corporation in Japan in 1990. Dimensions: 466x163x441. Weight 16.2 kg. Power consumption 450 W. Thanks to the standard transformer, it operates with a voltage of 120/220/240 V. Voltage Selector is located on the rear panel. Rated power 100 W at 6 ohms.

Frequency range 10 Hz-100 kHz +0-3 dB. You can connect up to 9 to the amplifier external sources. The sensitivity of linear moves is 150 mV at 47 kOhm. Also a must-have for stereo fans is a phono stage with a sensitivity of 2.5 mV and a frequency response of 20 Hz-20 kHz +/- 0.3 dB.
The Sansui AV-7000 has a bright tone block consisting of three adjustments: LF +/- 10 dB (50 Hz), MF +/- 6 dB (1 kHz), HF +/- 10 dB (15 kHz). Headphone output, balance and “Mono Level” and “Input Level” adjustments that I didn’t understand. Three pairs of output acoustic terminals, one of which is marked “Mono” for some reason. A sophisticated interrupter of the preliminary and final stages, consisting of three sockets: Pre Out, Power In; Pre Out Rear. And in addition to the left and right channels, there is again the “Mono” channel.
The amplifier has no tone compensation. But there are several “Surround Mode” settings installed. The tone block is turned off, but only at the seat input with the “CD Direct” key. The kit comes with a remote control with so many buttons that I didn't even try to figure it out.
We started listening with vinyl and 8 Ohm S90D (frequency range 25-25000 Hz, power 35 W, sensitivity 89 dB, dimensions 360x710x286, weight 23 kg). Very decent sound. The phono stage worked well. Having turned the timbre, I adjusted the bass to full (+10 dB), midrange in the middle (0 dB), treble to ¾ (+6 dB). Comfortable sound, but not deep enough in the lows. It was in vain that Sansyi engineers neglected loudness compensation.

Then we turned on the CD and changed the acoustics to 4-ohm Quadral (frequency range 32-22000 Hz, power 80 W, dimensions 220x450x300, weight 8 kg).
On the CD it played more convincingly, although it was a little harsh in the upper mids. But that’s what the tone block is for. I reduced the midrange to -2 dB, and the high frequency to +4 db. Played more smoothly. Sansui coped well with both 8-ohm and 4-ohm acoustics. It’s difficult to even say which is more expressive. We connected the S90D again. I played with the volume. I got the impression that at medium volume the Quadrals look more impressive. But turn it up louder and our Radio Engineering puts pressure on the Germans. In general, as one would expect, despite the greater declared power, the 8-kilogram Quadrals were inferior to the 23-kilogram S90D.
Summary – the sound is powerful, convincing and quite comfortable. The amplifier goes well with both 4 and 8 ohm acoustics, and the rich timbre block allows you to adjust the characteristics of the acoustic design of the listening room.
The sound nature of the Sansui AV-7000 reminded me of the Teac A-R600. Is it possible that Teas has a larger bass reserve due to tone compensation? Complementing the similarity is the fact that both devices play CDs brighter than vinyl. In general, the component is very worthy - solid weight, convincing power and bright sound.

A serious claim to the highest level of Hi-Fi. The disadvantages include the lack of tone compensation.
Without removing the Sansui, we connect the two-block Technix in parallel. Top of the line. Manufactured in Osaka (Japan) by Matsoshita Electric industrial corporation. Year of manufacture 1996-2000. Stereo Control Amplifier SU-C800U. Dimensions: 430x69x307. Weight – 2.7 kg. Frequency range 3 Hz – 80 kHz. The amplifier has 6 inputs: Phono; Tuner; CD; AUX; Tape1; Tape2 and 3 outputs: Tape1; Tape2; PRE OUT. The functionality of the device is minimalistic. In addition to the obligatory input, volume and balance selectors, there are only Bass and Treble knobs and a Tone button, which turns off the tone block. The amplifier is powered by a proprietary cable from the terminal. Moreover, its button turns on both blocks.
Power amplifier Stereo Power Amplifier SE-A800S. Power consumption 230 W. Dimensions: 430x136x348. Weight – 8.7 kg. Frequency range 5 Hz – 70 kHz +0-3 dB; 20 Hz – 20 kHz +0-0.5 dB. Power 2x65 W at 8 ohms; 2x85 W at 4 ohms. Damping coefficient 70-8 ohms. Number of inputs 2xRCA 1 V/33 kOhm. The amplifier has a headphone output and 2 pairs of speakers. They are switched using the Speakers A and B buttons and are illuminated by LEDs.
We connect the Quadras to Technix and listen to vinyl. Quite decent! Very. We listened to a couple of tracks. Switch to Sansui. And literally from the first seconds it becomes clear that the two-block Technix is ​​proudly called “Reference” for a reason. Yes! According to all listeners, the sound of Technics is more lively and expressive than that of Sansui.
Next we put on the CD. The sound is convincing, weighty, but still inferior to analog. Which is quite predictable for components of such high level.
We connect 8 Ohm S90D to Technix. And here we are disappointed - he plays frankly poorly. We connect 4 Ohm Electronics - they sing! Apparently the amplifier does not match well with 8 ohm acoustics. Or he didn’t like the S90D for some reason.
Summary. The sound is lively, expressive, with good detail. The device copes perfectly with both digital and analogue sound sources, and, as befits components of such high class The analogue, in terms of natural sounding, replays the CD.

And this is clearly audible even to an unprepared listener.
The disadvantages include some capriciousness of the tip when matched with 8-ohm acoustics. Plays with 4 Ohm without any issues.
And finally, the long-awaited Optonica SM-3636 HB. Produced in Japan in 1979 at the Hi-End division "Optonica" of Sharp. Made using “dual mono” technology, with separate transformers for each channel and independent power supply for the preliminary stage. The presence of three transformers seriously affected the weight - 14.5 kg. Power consumption 380 W. The amplifier has two phono stages and four line inputs. Frequency range 5-70000 Hz +/- 1 dB. Power 65 W. Dimensions 442x144x363. On the rear panel there is a chopper for the preliminary and final stages. That is, the amplifier can be used both as a pre and end.
The functionality of the amplifier is so rich that there is practically no free space on the front panel. In the tone block, in addition to the usual bass and treble adjustments (+/- 10 dB), there are two Turnover toggle switches with a gain of 600/300 Hz and 15/3 kHz. And also two toggle switches with switchable filters at 30 Hz and 7 kHz.
A thirty hertz filter is vital when driving a turntable. Also in the form of stylish toggle switches, tone compensation and tone block disabling are performed.
The amplifier has an output for headphones and two pairs of speaker systems. The “Speakers” selector has 4 positions: A, B, off and A + B. Closer to the volume knob there is a balance (+/- 10 dB) and a “muting” button - attenuation of 20 dB. Next are the input selectors, and the activation of phono preamplifier 1 is also made in the form of a toggle switch. And another switch, practically not found in modern “mode” amplifiers, sets the following modes: normal, reverse (swaps channels), mono, left and right.
A device specifically designed for audiophile listening. Two phono stages!!! You attach two turntables to it, put identical records on them, and with a simple click of the switch you compare the sound.
So! We connect to output A of the S90D, to output B of Quadral. We turn on the vinyl and alternately listen and compare.
Fantastic! Phenomenal!!! And again. At medium volume the Quadrals look more impressive, but turn it up louder and the S90D takes away the German competitor. After listening to the side of the record, we change the Quadrales to Electronics 25AC 033 (frequency range 25 Hz-31500 Hz, sensitivity 86 dB, power 25 W, dimensions 320x610x325, weight 21 kg, resistance 4 Ohms). And here the S90D couldn’t cope with its competitor.

By all indicators, Electronics plays brighter. Even greater sensitivity did not help radio engineering. 4 Ohm Electronics at the same volume level played more weighty and solid.
After listening to the vinyl we switched to CD. Very convincing. But not as deep and easy as on vinyl. For the frequency of the experiment, we decided to conduct a direct test. We put on the Eric Bordon My Secret Life CD and vinyl at the same time, and switched the toggle switch to compare the sound. Well, of course, all listeners liked the analogue better. The CD does not have such deep bass and airy highs. But the digital middle sticks out unnaturally.
Summary. The sound of the amplifier can surprise even the most experienced music lover. The tops are light, like a spring breeze; calm, natural middle; and the bass is so deep and powerful that it becomes scary for the speaker suspensions.
Uncompromising stereo reproduction quality. Phenomenal channel separation! The sound stage stands in front of the listener, dissolving the speakers and pushing apart the walls of the listening room.
Comparing Optonica with Technix and Sansui took no more than a minute. There was simply nothing to compare. When switching to Optonics, it seemed that it was playing quieter, but there was more music. The noise, chaos and confusion go back and disappear, and in their place the musicians come forward, take their place on the stage and begin to play, without obscuring or drowning out each other. This phenomenon is called legibility or detail and is present only in Hi-End equipment.
Taking advantage of the fact that all three amplifiers have a gap in the paths, Audi decided to conduct an experiment that interested all participants in the listening session. He suggested that the Optonica owes its phenomenal sound primarily to a strong pre-stage, and in particular to the phono stage. Having removed the jumpers, we connected the Pre Out Optonics interconnects, first with the Power in Sansui, and then with the Technix power amplifier.
But the miracle did not happen. The character of the sound has changed a little, but the balance of forces remains the same. Sansui is weaker, Technics is better. But no matter how hard they try, they cannot reach Optonics.

This publication opens a series of articles on improving audio equipment on our website.

Let's start with Technics SE-A800S amplifier upgrade, preamplifier of the same trademark SU-C800A, and improvements to the crossovers of the JBL TLX6 speaker system.

In the articles I will try to avoid citing unverified sources and will not give generalizing far-reaching advice, so that it does not turn out, like Igor Guberman, that “a thought thrown to the masses...”. I’m also against teaching someone about life and sending them to listen to music at the Vienna Opera; it seems to me that the music should sound good when minimized different types of distortion, and if you reduce these aspects all together, then it is this approximation to the original that gives listening pleasure. The articles are intended mainly for people who want to understand what to strive for next before doing more expensive purchase because it seems to me current situation In the world market, there is a huge gap between “sounding” equipment and equipment that doesn’t sound at all in the price category, and you can only find a decent-sounding device either in the professional line or for a lot of money. I would not start an upgrade without firmly believing that the engineering genius who created such equipment thought first of all about quality. I would also like to give a few simple rules, which will help you avoid the mistakes I made if you want to tweak your existing hardware yourself.

1. You should never start work in a state of physical or emotional fatigue. This applies to both working with a soldering iron and listening for quality. The difference in sound can be so shocking that, for example, an amplifier or speakers that were “successfully modified” on weekday evenings will turn out to sound completely inept on a weekend.
2. Working with the selection of coupling capacitors requires the obligatory implementation of the first rule, because very often the difference in sound, firstly, cannot be assessed immediately, and secondly, it is often simply a matter of taste. But in any case, it cannot be discounted when tweaking, because the original capacitors usually no longer have the correct properties after many years.
3. Before modification, it is advisable to acquire some kind of reference device for delivering sound to the ears, be it an amplifier with speakers or headphones. Here I am omitting the obligatory presence of a pair of well-rested ears and maybe more than one pair. Sound sources can differ greatly in sound, for example, even in one studio recording by one musician, what iTunes™ produces may not coincide strikingly with what is recorded on the CD. And it’s not about harmonics or the frequency range of playback devices, but about the work of the sound engineer.
4. You should not blindly trust instrumental measurements of phase response, frequency response and harmonics (here in descending order). For example, measuring the frequency response of acoustics requires the presence of a soundproofed room, otherwise it can only serve as a guide for an upgrade. I don’t have such a room myself :)

When we first turned on the amplifier, speakers, CD player and various sound cards, including Mackie Onyx Blackjack, after a 20-year break, it turned out that there was simply no sound. And even if many years ago, immediately after the purchase, it seemed that in another more spacious room the sound would be better and more beautiful, and in the salon I chose the speakers in conjunction with the NAD amplifier from several, including more expensive options. Now the sound was simply amazing with poor, dispersed bass, replacing high frequencies with a hissing, hissing richness of sounds. And only the mid frequencies sounded beautiful. It must be said, of course, that the tweeters had already been modified by the child according to the principle of removing the protruding membrane inside, so I immediately made a discount for the HF. Below is a photograph of the entire inheritance.

I started with the speakers; a quick glance at the crossover board showed that it was quite well made, although non-polar capacitors were used. Replacing the capacitors in a Zen-like manner gave practically nothing. This was also visible in the above graphs. The harmonics have not disappeared, although they have become a little weaker, the frequency response has changed a little, but not enough to say that the cause of the bad sound has been found. Only after the replacement it seemed that the treble began to crackle less on strong notes, and the bass became less vague. By the way, this can be seen from the transient characteristics below. I attributed this to the greater selectivity of filters with newly installed capacitors; apparently, the characteristics of the old ones had deteriorated greatly.

The most interesting thing is that JBL used VENT brand capacitors, which can still be found on Chinese websites. I photographed them next to the board. The board shows that the replacement has greatly increased the dimensions and weight of the crossover. A Zobel circuit (series connected 4 ohm resistor and 15uF capacitor in parallel with the speakers) was also included on the woofers to increase the efficiency of the low pass filter. By all accounts, I urge you to read the book by Aldoshina and Voishvillo “High-quality acoustic systems and emitters,” which not only has not lost its relevance in our time, but has rather become extremely popular. The efficiency of filters is highly dependent on the impedance of the circuit behind the filter, in this case the speaker. The calculation of the capacitances and inductance of the crossover is based on the resistance of the speaker at direct current. But due to the inductive nature of the dynamics, the impedance of the circuit increases greatly with increasing frequency. This graph shows how, as the frequency increases, the LF speakers in JBL (green curve) begin to sound in the midrange from 2 to 6 kHz. MF - blue line. Together without HF - red.

In other words, in order to correctly set up a crossover on a bass-midrange connection, you need to put a Zobel circuit on the woofer, and in order to remove the midrange speaker from the high-frequency range, you need to put a Zobel circuit on the midrange speaker. The Zobel circuit (otherwise called a correction circuit in the book) sets the impedance at the filter output equal to the resistance of the resistor. Which in turn is equal to the speaker's DC resistance. As the frequency increases, the impedance of the speaker increases, and the impedance of the capacitor decreases in equal proportions (formulas in the book), which makes the total resistance unchanged. If the calculation of the capacitor is questioned only by the most sophisticated audiophiles, then playing with the resistance of the resistor allows you to change the balance of forces on the sound stage to some extent. Since 2 10-ohm LF speakers in the JBLTLX6, before the subsequent modification of the amplifier, slightly oversaturated the range (this is not visible on the frequency response, only in the form of harmonics), a year ago it was decided to install a 4-ohm resistor, which is less than the resistance of two 10-ohm speakers connected in parallel. This is because the Zobel circuit reduces the speaker's output throughout the entire range, which is not necessarily a bad thing since you need to look at the entire range of the speaker and of course listen. Although the sensitivity is slightly reduced, the effect of the application may be more important. Pay attention to the nonlinear distortion factor in this figure over the entire frequency range - the blue line. If the frequency response can still be accepted as more or less normal, then the CG is too off the charts. In this case, the distortion is all from the power amplifier, as will be seen later.

The biggest problem with the sound of these speakers was in the high frequency range from 7 kHz, the midrange and high frequencies were not in phase. If two adjacent speakers are out of phase, both the frequency response and the impulse response, as well as the overall perception of sound, suffer. In the figure above you can see a dip in the 3-6kHz range on the blue line, albeit a small one. For example, when there is a phase mismatch between the LF and MF-HF in two-way active systems, which are very popular today, it seems that the performer at the crossover frequency seems to be taking a step back, hitting a loud note, or is simply hard to hear. This may manifest itself differently on different recordings, but it’s as if you want to turn your head to hear clearly. Since I subsequently replaced the tweeters with non-deformed ones, also made by JBL, but of a different model with a different resistance, I also had to replace the capacitor with a 3.9uf with 4.7uF initially in the HF circuit. The woofers were carefully taped with tracing paper around the perimeter in places of tears, and, if possible, using the dash-dotted method so as not to influence too much. At first, this affected the sound like barbarity - the bass sound became roughly accurate, the softness seemed to have disappeared. But time has shown that everything is not so bad, apparently the glued areas have softened. By the way, this does not affect the harmonics in any way; I measured them before and after (read on).

The midrange circuit also underwent changes - after installing a 4 Ohm resistor (+C 15uF) in the Zobel low frequency circuit, the midrange sensitivity was also reduced by a 2x6 Ohm divider to match the sensitivity of the low frequencies and high frequencies. Here is a diagram of the modified crossover.
Yes, and don’t forget the most important thing if you have such speakers. JBL until some year used a red connector to indicate the negative connector when connecting to an amplifier!

The original crossover circuit also had a resonant RC circuit, but it had such a bad effect on the HF that I removed it immediately. Also here I omitted the attempt to cover the inside of the case with bitumen self-adhesive material (it is still inside). The work is dirty, the smell is strong, the result is not obvious. I don't want to remove it anymore. Filling the space with batting was already done at the factory and transferring from one compartment to another does not bring any result in better side, only if you remove it from the cone by which the midrange speaker is separated from the rest. Then you can see a surge of resonances and the work of the midrange speaker in the high frequency range is enhanced.

The general conclusions regarding the speaker tweaks are as follows. If you are modifying acoustics that at least some time after production sounded good, then you need to start from their best range. For example, the midrange sounds great in these speakers. He sings so beautifully that it was even a pity to put a voltage divider in front of him. The voltage divider played a very good role in achieving in-phase across the entire range. The frequency response has leveled out, the phase rotation has become smoother without sharp turns. Modern hi-end speakers are made using more precise technologies with a higher quality factor, which gives them great advantages over this system, but this is only if we are talking about hi-end. The clear delimitation of the frequency band by crossovers leads to problems with the natural sound of natural instruments, although electronic music sounds equally good on old and new models. But broadband systems are also becoming increasingly popular among audiophiles. And to be honest, I was more worried that the Technics 800 simply couldn’t handle the impedance of these speakers of about 8 ohms, something was missing. As it turned out, I had no reason to be afraid - read on.

For those who are not familiar with the work of Japanese engineers from Technics, I will note that the preamplifier is not independent device, although located in a separate building. Power is supplied to it from the main unit, but all logic and work with the remote control is under its control. Here are the service manuals, kindly reproduced online:

At the same time, at first glance, the weak point is the cable connecting the units with power and transmitting both constant pressure for logic, audio and also alternating voltage, it has never failed. This is the so-called virtual battery circuit. All DC power circuits leaving the power amplifier and at the pre-input pass through 1uH chokes. We must pay tribute - none of these circuits emit noise at the network frequency, even though the board is not shielded. But perhaps due to the fact that all the logic is implemented in the preamplifier, including the 4 MHz resonator, this is the noisiest place in the complex. Although shielding boards does not provide any benefit. I confess that I haven’t gotten involved with food filtration yet. If you disconnect the cable from the power amplifier input, the noise is also audible, but the decibel is 10 lower.

It must be admitted that from a distance of 1 m from the speakers, the noise is absolutely inaudible even at full power. The tone control slightly adds noise, but only to the extent that it is turned on for high-frequency boost.

Well, if it’s easier to control the amplifier from the remote control, which also controls all devices, including a CD player and deck, and supplying a signal to the amplifier directly from the sound card produces a not very dynamic sound, then it’s probably not possible to pump up the AN7062 chip, which operates from +-48V So simple, it was decided to simply change the connectors, coupling capacitors and op-amps in the pre-amplifier with modern high-quality components. It was decided not to abandon power supply chokes and mute transients, because the test showed the absence of any influence on the signal. The cable from the balance control was removed, as it severely limited the stereo range. Replacing op-amp IC301 with LM4562 greatly improved the dynamics of music playback. A certain vintage chic appeared in the sound, and noise also decreased. You can try replacing the coupling capacitors with something audiophile, but so far I’m quite happy with the sound from the fairly standard replacement that I made from Sanyo and Chinese bipolar Elum 47uF 25V. As it turned out, the main problem was in the mind.

It was difficult to start upgrading the power amplifier due to the lack of high-quality capacitors on hand, and to be honest, I was not sure that it would help. Yes, I saw 10000uF capacitors in later Technics models, but on the board there were such letters carved in gold letters Technics56 V 8200uFJAPAN that the hand simply did not rise to change them. I started by replacing the input coupling capacitors C401-402 50V-4.7uF with less noisy ones. The noise introduced by this capacitor is determined by the high bias voltage at the input of the microcircuit, about 100 mV, and the leakage current does its job. Oddly enough, the best replacement compared to Nichicon and Sanyo turned out to be ELUM bipolar capacitors, which not only removed noise, but also increased HF and LF transmission without changing the tonal balance. For example, Elna Tonerex makes the highs brighter and the lows too energetic.
A further update was made with electrolytes in the audio path C501, C502, C503, C504 on ElnaCerafine 10V100uF. I highly recommend these capacitors, but probably not for fans of electronic music. It seemed so. Subsequently, power, ground and output buses were made from an earthen silver-plated copper bus from one old board and replaced throughout the amplifier (the buses are in red heat-shrinkable tubes in the pictures).

The jumpers under the buses, slightly thicker than usual on the boards, were soldered off. The input connectors were replaced with gold-plated ones, but without much fanaticism, for 3 bucks apiece. The sound became beautiful, but not balanced. Very vintage, analog, with soft, non-straining highs. But in the field of low frequencies nothing has changed radically. There was some kind of dispersion. And recently I saw Elna10000uF on the store counter for $10 apiece. I replaced the standard ones with gold letters and almost fell out of my chair. By this time I had already completed the CD upgrade, which began to sound better than any source I had heard before, even on headphones. I tried it with this source. I must say that I did not expect so much from replacing gold Technics capacitors with gold-plated Elna ones. This was the final step in upgrading the system. Now I can listen to any music on this amplifier with great pleasure. There are already grateful listeners. No wonder I waited so many years.

As you can see in the pictures, I placed the speakers on stands made from hubs from the car market in order to “untie them from the floor.” So, after the upgrade, no decoupling is needed. Low frequencies are where they belong, that is, below. To confirm the theory that the capacitor in the PA caused harmonics, I once again measured the frequency response of the system after upgrading it with the HolmAcoustics™ program with the KAMHype™ instrumental microphone (its rise towards HF must be taken into account) and the MackieOnyxBlackjack™ audio sensor. I am attaching a screenshot. Blue lines - the tone block is turned off by the button, red lines - it is turned on to fully raise the bass and treble, green - the tone block is in the middle. Please note that the phase at the MF-HF junction remains constant, and the level of harmonics has decreased compared to the previous graphs. The first is the result of a voltage divider for the midrange speaker, the second is the replacement of the PA power capacitors. I would also like to draw your attention to the change in the transient response at the bottom for the tone block turned on full. Since the tone block is included in the circuit feedback Op-amp of the pre-amplifier, then on the green curves (TB is turned on, but brought to the middle) it is clear that this correction circuit corrects the dips and peaks of the frequency response. All the transient characteristics below show that when the “jump rope” moves from the negative region to more than 0, the next peak is slightly broken - this is a defect in the crossover, or more precisely a consequence of the fact that there is no bi-amping in the system, and perhaps it would be enough to do biwiring. The 22uF capacitor in the midrange circuit affects the low-frequency and high-frequency speakers. The capacitor in the LF circuit affects the MF and HF. At the same time, on the crossover boards, I separated the ground circuits as much as possible so that the currents of one speaker, after filtering, did not flow with the currents of the other. It is possible that I will continue upgrading the preamplifier in the near future. Although the sound of the system is already very pleasing with its clear sound.

P.S. While I was writing the article, I had a desire to try to remove the voltage divider in the midrange, but this increased the humps in the frequency response in the middle and lower frequencies, and did not remove the dip from 800Hz to 2 kHz. But it doesn't matter. It is important that the speakers sound. I don't listen to numbers and graphs. Maybe for this waywardness of sound I chose these JBLs at one time, which can no longer be found on the Internet. Vintage acoustic ghost.

Addition from 08/15/2014

Update from 08/27/2014

Until recently, the preamp seemed to me to be the weak link in this trio. But replacing capacitor C701 1000uF with TEAPO (low ESR) 2200uF from computer unit power supply made it possible to further clear the spectrum of interference. The microprocessor, not knowing anything about the high-level tasks it solves, greatly pollutes the power bus and the ground common to the analog part. The HF sound became even higher. The second modification boiled down to replacing ceramic capacitors C315, C316, C321, C322 0.015uF in the tone block. Original capacitors in glass cases can hardly be called a good solution. Replacing with film ones made it possible to improve the reproduction of low frequencies, which began to be lacking as the path was cleared of noise, but also, as it turned out after some time, the high frequency noise slightly increased to an audible level. I assume that this is due to capacitors C321, C322. They still stand in the DX arm of the tone control. Regarding objections about how 5V can affect audio, I will say the following. The supply voltage to the pre-amplifier op-amp is controlled by a microprocessor through transistors Q601,602,603. It is the power supply to the microprocessor that we bypass with this capacitor. Also, HF components can easily flow onto adjacent tracks, due to the fact that their frequency is quite high.

Sergey Begaikin specially for the site website

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About Sergey Begaikin

I have been involved in electronics since childhood. In the 8th grade I dreamed of hifi devices, but I only had to solder comets. At the same time, I signed up for the NTB to recharge myself with English-language magazines, I don’t remember the name, and purchased Shkritek’s book “A Reference Guide to Audio Circuitry.” Although, to be honest, the second half was a dark forest for me then by digital standards. Then there was an institute with the theorems of Kirghoff and Kotelnikov, but I completely forgot about the book. And now, 20 years later, having in my luggage a completely soundless Technics musical complex and a wealth of experience in telecommunications, I suddenly wondered if it was not easy for me to bring this whole thing to fruition. Or say goodbye to your dream and throw it in the trash. I chose the first one and did not regret it. True, almost a year passed in search of the truth, but thank God I achieved my goal. Now I’m ready to share my experience in finalizing it with everyone. Although my area of ​​interest is not limited to just one music center. I don’t consider myself an audiophile, and if there is a confrontation between engineers and audiophiles, then I’m more likely to be with the former. Although practice this year has shown that the latter are not always wrong either.

Comments on VKontakte

668 thoughts on “ Technics SE-A800S amplifier and JBL TLX6 speakers: in search of lost sound.”

35. It’s a pity that you didn’t leave reviews on the fragments that I post. Well, I hope you'll listen again. Today I decided to continue refining the bypass paths for IC202, since anyway, with the cut off tracks, it will not be possible to allow the inputs to be recorded. Since there are 2 paths for this recording (tape1 in, tape2 in), we had to unsolder 3 jumpers and cut one track. The diagram is here. The result affected the detail of low frequencies. On the one hand, this is good, on the other hand, I was already so accustomed to the sound of an amplifier without a tone block (even on headphones the sound was more characteristic than on a headphone amplifier in a CD), that at first I didn’t even believe it. Both headphone outputs were almost equal in sound with the tone control turned off. On the other hand, due to the fact that the low frequencies have become more detailed, now I want to increase the timbre at low frequencies. In my opinion, nothing has changed on the HF. The bass had such a characteristic vintage HM, for every drum beat. The sound has become more local. Before modifications, the low ones were simply spread out on the floor. Now the double bass sounds, firstly, shifted from the center (where it is shifted), before it almost always sounded in the center. Secondly, it began to vibrate strongly, and it was scary for the speakers. But it's beautiful.
    I would sum it up like this. Since all outputs of IC201 are paralleled channel by channel, any impact even on inactive 7 channels leads to changes in the sound, albeit through the huge resistance of the keys. 2 outputs per channel from IC202 went to the Tape1 IN and Tape2 IN inputs, I removed them. If static was generated at the disabled inputs, now it does not reach the signal circuits. Also, the capacitance and inductance of the inputs probably decreased slightly, and the impedance increased. I also made 2 plugs from unused RCA jacks. I closed the contacts inside and put them on the Phono inputs, although you can put them on any. Tomorrow I'll try to do it for the remaining entrances.

    

    And here is a photo of the switch, although it’s not quite finished yet, but all the elements are already in place. ic201,202 will be dismantled. Instead of ic201, a new switch will be soldered with long leads into the holes. I decided to make four entrances.

    

    Yes, I'll probably come up with something too.

    Dimensions 15 by 60 mm, all installation is done with wires.

    WarlocK, change the input capacitors in the PA already. You can see how bogi has overtaken everyone :-) bogi, be prepared that the sound will change greatly. I'm in shock for the second day. Previously, with jumpers, the sound was balanced, but in any composition it relied on the floor, on the acoustics of the room. Now he sounds without support. This is so unusual. The high frequencies have also become different, like a razor blade without a ceiling on top. What’s unusual is that, let’s say a piano, if you imagine it in a room, it still relies on the room with its low frequencies, well, at least it should. You, bogi, with a switch should also get something similar, but with fewer harmonics. For some reason it seems to me that you will want to give jazz again

    I’ve already unsoldered the switches while I’m listening through the rl201, as I described above. I switch two inputs. Without an analog switch it is definitely better.

    • Somehow I became confident that it would be better without switches. Today I've been comparing the CD input and others that remain on the same switch all day. The sound of drums from the switch is clearer, without blur, and all kinds of double basses are also better localized in space. In short, now there is the same amount of bass in both places, but from the switch the lows are somehow softer and there is less rumble that accompanies each hit. That is, I want to raise the regulator both at the CD input and at the others, both at LF and HF, for example, for 2-3 hours. But the high ones, on the contrary, sound slightly muffled through the switch, and are localized equally well in space. I have a theory that through the switches fewer low frequencies return to the ground in the form of some kind of reflection (there are long tracks, and even cables) and the result is a more localized sound in the low frequencies than directly in the relay. The resistance of an open switch is about 100 Ohms. Maybe this gives some kind of decoupling effect from the input? And switch harmonics are added to the RF. All switched inputs (Aux, TApe1, TApe2, Tuner), except CD, sound the same.
      The yellow Elna capacitors and shunt switches haunt me. Like all RC switches in general, both for power supply and for switching relays on IC202. I just got a batch of Elna (not audio) 1uF 50V, I want to try installing 4.7uF 50V instead of the installed ones. Or try removing 0.01 capacitors from the power supply to the switches. Or play around with the 1k resistances through which power is supplied to the switches. Maybe the HF will improve and nothing will have to be changed. In general, I got the impression that switches, hanging as if on the power supply of an op-amp, themselves can create the effect of some kind of smoothing filter with their capacitances and resistances on the power stabilizer. This would explain why the choice of capacitors for the pre is so important. Thus, the resonance frequency of a 1k 4.7uF RC circuit is 33Hz, and for a 1k 0.01uF circuit it is 15915Hz. This wiring is of course important to prevent self-excitation of the op-amp, but still... The second chain can have a strong influence on the RF. I understand, bogi, that you are no longer interested in this, but for WarlocK this can be useful, since he wants to save the number of inputs without resorting to radical methods.

      • Sergey, it seems to me that you are engaged in isotericism. On many audio sites these switches have been lowered to the lowest possible level, but you are making candy out of them, why?

        • In order: 1. analog switches are switches based on field-effect transistors, nothing more, which are still used today. In a narrow sense, we can even say that these are discrete elements, since the drain and source “stick out” outside. They are still produced by famous companies, like Ti or Analog Devices, and what is most surprising is that they have characteristics that are either not superior to this Toshiba microcircuit, or much worse. At least for audio applications (for example, Kharmonics).
          2. Just as everything is poison and everything is medicine, so details are neither bad nor good. There are limitations to application and feasibility. That is, it is impossible to compare these switches with the carburetor in VAZs, as an outdated device. I have several relatively modern sound cards. Not pret-a-porte, of course, but not the cheapest either. None of them sound like this amplifier on headphones. That is, they simply provide sound, high-quality, recognizable, each card has its own, but not so musical. Do you know what I mean? Their sound just doesn't turn you on.
          3. Every time I change something in the circuit, I understand that I am simply correcting the actions of that Japanese “ensign” who either supplied cheaper parts or tried for some reason to increase the functionality (such as recording on a tape recorder) to the detriment of overall quality. And all this at a time when other manufacturers like Marantz already realized that people would “love” if you hired a good turner to turn cases, because people could be explained that form follows content. I respect the Japanese for sticking to their goals. Canon and Nikon have proven, for example, that they are the best in cameras because they did not bend to the market, but, on the contrary, waited until the market grew for their products. In the case of Technics, they simply fell victim to sharks like Sony.
          4. By and large, there are no ideal amplifiers. The characteristics that this kit offers are no worse than those of the best examples of modern audio products. And the sound has its own character, which you, bogi, are trying to replace with the sound of a microcircuit that is recommended on audio sites. Even by the fact that you easily got rid of capacitors, without which I can’t imagine the sound, we can say that we have completely different approaches to listening.

          • The approaches are different not to listening, but to circuit design. With bipolar power supply, coupling capacitors are not needed. The characteristics of this kit are good, just modern technology stuffed with all sorts of electronic reg. gr. commut…..to put it mildly, not ice. And for reasonable money with good parameters, only used ones.

            My preliminary op amp is opa2132 “original”, not because it is recommended on audio sites, but because it sounds better than the standard one and Chinese fakes.

            Again, point by point: About the uselessness of capacitors, this is a rhetorical question. Everyone decides for themselves.

            Regarding the OU, you still haven’t provided photographs of which ones play well and which ones play poorly. How to distinguish them?

            It was thanks to the first device with a virtual battery, in which a real battery was installed, that the entire series began to be called. In those years when the outputs of other units did not produce more than a volt, a pre-amplifier was a mandatory element, as it made it possible to achieve the signal level needed to drive the PA. The idea of ​​moving the power supply to another case is now used all the time. Yes, there are problems, but they can be solved by moving the capacitors, which is what I did. But with the increasing popularity of integrated amplifiers and the advent of devices capable of driving them, for example, with voltages of 2-3V, the situation of device compatibility has not disappeared. Selecting an amplifier for any source is very difficult. And it is precisely this task that, in my opinion, this preamplifier successfully copes with. But of course, after a little modification. Matching impedances at different frequencies, not just levels, is a difficult task. And as I see it, switches can do this. I've just heard how he can play under certain conditions, and I'm trying to find ways to get him to play that way all the time.

      If you Sergey do not have enough HF - C 401, 402 on Elna. I'm curious what you will hear on the HF on your acoustics.

The capacitors arrived, interestingly, both had a charge; when measured, the voltmeter showed 4.7V; when discharged with an ammeter, the current jumped to 0.1A. All inscriptions appear to be new and not soldered, very clear without smudging.

• When are you going to install them? 33 thousand is of course wow!

36. Matching impedances at different frequencies, not just levels, is difficult. I agree with this only in relation to acoustics.

    “As for the OU, you still haven’t provided photographs of which ones play well and which ones play poorly. How to distinguish them? I don't know. The lt1364 purchased on Aliexpress were not working at all. OPA2132, which is now produced more than 10 years ago, was not counterfeited then. OPA2132 was compared with lme49990, LM4562, AD797 and settled on OPA2132. Sergey, I saw photos of your exploits only at the beginning of the topic.

    Regarding the virtual battery. It has nothing to do with battery power; it is a purely circuit solution for a power stabilizer. Study math. part of Seryozha.

    • Why have you been teaching me all my life? There is no special technological solution different from the diagrams in the Radio magazines of the 80s. The fact that they used field grass doesn't mean anything. The fact that all the circuits between the blocks were hung with chokes does not add virtuality either. This is pure marketing. Virtuality lies only in the fact that the power supply is in a different case, so now many devices are made this way and no one talks about virtuality. Have you ever wondered why a battery (battery, to be precise in translation from English), and not a virtual power power supply, for example? The Japanese should not be mistaken for weak experts in technology. My version: initially SUC1000 (1995) was the starting point for the series, the main idea, and it was on it that the inscription BATTERY OPERATION appeared. And the fact that they started writing on the remaining VIRTUAL BATTERY OPERATION blocks is already a tribute to fashion and trend. SUC1000 alone cost about 60,000Yen - that’s 600 USD. Consider, SUC800 together with SEA800 cost 300USD. And it's just a matter of battery. Of course, this is not technologically advanced and expensive, but in order to comply, it was necessary to come up with a “new” filling in order to sell it cheaper, “but of even higher quality,” as usual.

I replaced the Elna in the UM with a Nikikon 100 uf, the sound came back dirty as it was before the Elna but does not tire, I replaced the C 309, 310 with an Elna of the same rating, more midrange vocals became more audible, I covered the pre and UM with foil, the sound became cleaner, less dirt and warmer HF softer, I decided to return Elna back to the UM, my ears don’t hurt, only now my head is starting to hurt, but the sound is cleaner and more pleasant, in short, along with a good part of the necessary frequencies that are missing, they let in some noise that puts pressure on the ear, but I don’t care about these noises I don’t hear it, I solder the nicikon back.

I want to make a short lyrical digression to explain something. In one well-known publication in narrow circles, whathifi.com. There are sections with reviews of all new hifi equipment. And here’s what, for example, is written about the “Rega Elicit-R” amplifier in my translation, preserving the style and punctuation:
“What immediately grabs your attention is the correct sense of timing: the dexterity of rhythm control is extremely impressive. Kate Bush's "Watching you without me" renders all instruments with impeccable precision while keeping the arrangement precise and cohesive. The amplifier is especially talented in vocals: Kate's voice sounds airy and delicate.
The Rega Elicit-R simply digs out the details in the material. The drums have a realistic and springy impact, while the ambient sound on Clint Munsell's Moon sounds impressively solid.
While the old Rega Elicit exhibited dynamic restraint, the Elicit-R is much more affable. The composition at the amplifier output allows loud parts sound solemn, while quiet moments show off plenty of detail. Some might call the Elicit-R a bit thin and bright sounding compared to amps like the Roksan Caspian M2 or Heed Obelisk Si, but it doesn't try to smooth out any rough edges as it doesn't trade warmth and smoothness for clarity. »
The second translation refers to the praises of the Arcam A19 amplifier:
“The first thing you'll notice is the scale, really big to fill the room with clear, open sound. We played a variety of musical styles, and the Arcam provided overall good balance and detail. The synthesized bass notes from the Social Network On We March soundtrack hit with depth and precision, keeping pace with the melodic piano. There's a good sense of weight and authority, keeping the dissonant overtones of dark surrounds within the stereo sound field. The general presentation of the amplifier leaves a feeling of excessive sedateness, and I would like to encourage Arcam to be a little more bright and involved.” As we see two slightly opposite reviews. The first amplifier costs more than 2000usd, the second more than 1000usd. As I refined the amplifier, using Elna as well, I could hear changes in one direction or another. Elna brings the amplifier closer to the first category, but at the same time makes it slightly lightweight and skinny. Some technological solutions, such as running the ground directly at the op-amp, bring us closer to a certain ideal and set the bar even higher. But at the same time, in some rare cases, which now cannot be called a mistake, one could hear such a beautiful sound that can be compared with Eleicit-R, but at the same time it was not at all too bright, because it also gave a low-frequency fuse. Unfortunately, this is some kind of transient condition in this amplifier, and I assume that it owes this effect to the switches, which, as it turns out, are susceptible to static and are highly dependent on power supply. Here on at this stage I would like to understand this issue. Now the sound of the modified amplifier cannot be compared with the first category in terms of ringing (I removed Elna from the op-amp supply). But it has long outgrown the second category, probably after replacing the power capacitors in the PA. Low frequencies sound quite good enough to light up the neighbors not with a muddy hum, but with deeply developed drums. But Elna doesn’t have the sonority or fluidity either. So I’m sitting and thinking, shouldn’t I leave everything as it is, or try to experiment with capacitors in the feedback?

• Yesterday I took off the cover of Um in order to completely remove Elna from the entrance and realized that the Nichicons that I installed last time instead of them (from which the HF went away) were 100 UF 50v instead of 4.7 UF 50v, I double-checked it again, and the truth is why I installed them is not clear , dug into the details, found two 10 UF 50v, one brand Unite, the second Nova and, for lack of a better one, installed them. I couldn’t leave the thought that you Sergey heard the background, it seemed to me that this was a recording of the track and the noise before the phonogram can be attributed, say, to the digitization error in level on different tracks, it is also different, but the only thing that could serve as a background was the audio cable that replaced the jumpers to the speaker terminals passes next to the power cable, almost touching, slightly bent, increasing the distance between them. When I first turned it on, I was surprised, the high frequencies remained in place, their excess was gone, now there was no unpleasant ringing at the peaks, and the low frequencies from the hum moved into the bass drum, adding drive, now even Kipelov’s album began to play, the distortion sounded more driving and more voluminous. I listened for three hours, the unpleasant effect was gone, everything was beautiful. I'll listen, time will tell. It would be necessary to order additional condensers of different denominations; there is a catastrophic shortage.

  • You amazed me, I don’t even know what to think. That is, the cable was in contact with the cable from the transformer? It seems to me that this certainly could not have such a meaning for the background and low frequencies. Think about what else you touched when you opened the lid. Maybe the train has been fixed?
    I highly recommend that you check that the midpoints of the transformers in both loops in the PA have contact in the connectors. I just remembered that I heard the same sound in the CD 770D, when, during the next disconnection and connection of the board, the middle point wiring bent in the cable and shorted to the adjacent trans contact. It sounded similar. There, as a fuse(?) on the transformer board, a low-resistance resistor burned out.

    • No power connectors, just soldering.

      That is, the capacitance of the capacitors cannot have such an effect? Or maybe Elna just doesn’t fit there or it’s a defect... although in the near future replacing C 309, 310 with Elna gave a positive result, they raised the midrange.

      The problem is in the audio processor, why couldn’t such a background be understood from it? Even now I’m listening without it, it works like a spectrum analyzer from tape 2

Dear

buyer!

Thank you for purchasing

of this Technics product.

To ensure optimal

performance characteristics
and safety, carefully
please read this

instructions.

This instruction manual
Applicable to the following systems.

Security measures

Manager

amplifier

Amplifier

POWER

This instruction manual
however, basically explains the work
Zi-A9000M2 systems.

Safety precautions...................................2
Connection........................................3

Front Panel Controls...4

Listening to sound...................................4

Remote control operation......................................5

Specifications...................... 6

Accessories

Power cord...................................................
Amplifier connecting cable.
Stereo connecting cable...........
Remote control (RAK-Zi228\L/N)...................

Location

Avoid placing the device in places where

subject to action;
direct sunlight;
high temperatures;

High humidity;

Big vibrations;
on uneven surfaces. (Install

device on a flat, level surface.)

Such conditions may damage the chassis

device and/or its other components and

shorten the service life of the device.

Installation

Never place heavy objects on top

machine or the power cord.

Voltage

It is very dangerous to use high voltage

AC power, such as power

air conditioners.
With such a connection, it may occur
fire.

Cannot use power supply

direct current.
Be sure to check the power source

especially on ships or other places,

where direct current is used.

Precautions for
using the power cord

Avoid scratches, scratches and

connection of the power cord, since this
may cause fire or electric shock.

Excessive bending should also be avoided.

pulling or cutting the cord.

When unplugging from the outlet, do not pull the cord,

as this may cause electrical
hit. When the power is turned off, firmly
grab the fork.

Never touch the fork with wet hands

to avoid getting serious

electric shock.

Foreign objects

Make sure that no foreign

objects such as needles, coins,

screwdrivers, etc. accidentally hit the device
through the ventilation holes.
Otherwise you can get
serious electric shock, or apparatus
may spoil.

Be extremely careful about hitting

water or other liquids onto the device or
inside it. because this could lead to
fire or electric shock.
(If this happens, then immediately
unplug the power cord and contact
dealer.)

Avoid spraying near the device

insecticides, as they contain flammable
gases that may ignite.

Cannot be used to clean the device.

insecticides, alcohol, paint thinners
and other similar chemicals, since

they may cause peeling or

clouding of the body finish.

Repair

> If you have problems with this

Allah, then never try it yourself
repair it, disassemble it or
redo.

As a result of ignoring this

warnings can get serious

electric shock.

>If there are any problems with the operation of the device

(the sound disappears, the backlight goes out
indicators, smoke appeared, etc.),
consult your

dealer or authorized service

Turn off the power to the device unless

use it for a long time
time. Otherwise it shrinks

its service life.

WARNING

Do not install on this unit

cassette deck or CO player.
Emitted from the top surface

This unit may become warm
cause of cassette malfunction or
CD.

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ventilation be closed
holes, do not place on this
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control amplifier for this
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