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Two vintage Technics amps measured: SU-V900 and SU-V90D

elberoth

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Bought those two out of pure curiosity and for their sentimental value. I used to have the Technics SU-V900 back in 1990 - that was my first 'real' piece of hi-fi. A school collegue used to own SU-V90D - the previous top of the range integrated. As you can imagine, beeing competitive teenagers, we have never settled which one was better :)

(mine was more expensive, bigger, heavier, had dual mono PSU ... so I've always thought it was better; interestingly it is the SU-V90D which subjectively sounds better driving my Magicos M3)

rqKHqd.jpg


Technics SU-V900 (AD 1990)

Rated power (1% THD + N, 1 kHz) [W]

1 channel / 2 channels:

8 Ohm 147W / 147W
4 Ohm 228W / 228W

Sensitivity (for maximum power) [V] 0.25
Signal / noise ratio (A-weighted filter, with reference to 1W) [dB] 79
Dynamics [dB] 101
Damping factor (relative to 4 ohms) 71

Technics SU-V90D (AD 1986)

Rated power (1% THD + N, 1 kHz) [W]

1 channel / 2 channels:

8 Ohm 126W / 126
4 Ohm 202W / 155W

Sensitivity (for maximum power) [V] 0.19
Signal / noise ratio (A-weighted filter, with reference to 1W) [dB] 85
Dynamics [dB] 106
Damping factor (relative to 4 ohms) 66

Measurements:

Frequency characteristics: the reference level (0 dB) is 2.83 V output voltage. One channel measured.

THD + N vs power: distortion (+ noise) for the assumed output power range, from 0.1 W up to rated power. One channel measured.

Measured using Neutrik A2D

technics900-moc txt.png

technics90-moc txt.png


technics900-fft txt.png

technics90-fft txt.png


technics900-pasmo txt.png

technics90-pasmo txt.png
 
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Timbo2

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Reminds me of my early HiFi days. I have this 110W/channel Yamaha sitting in storage with no idea what to do with it!

Yamaha AX-700 17.jpg
 
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Vintage57

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Measurements like these would lead me to believe they would sound as good a comparable powered current amps.

Any thoughts?
 

restorer-john

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The 'measurements' are very suspect.

The THD vs power output for a start. I haven't seen or measured any quality Japanese amplifier (plenty of Technics included) that exhibits THD at low levels (under 1Watt) at nearly 1%. That is plain wrong. Yes, noise can contribute at low levels, but consider these amplifiers have specifications at least 10-100 times better than his graphs are showing. I have plenty of amplifiers here, including a SUV-660 on my bench right now- I'll run a few tests on it just for fun and post them.

Most of the amplifiers I work on, collect and restore (many, many hundreds of them) push the abilities of my test gear to determine ultra low level THD. Consider even the connections to your dummy loads can alter THD by 10-20 times when you are at low levels. Ensuring you turn off and shutdown WiFi, computers and SMPS supplies can make the difference between a spray of spuriae burying your harmonics or being able to see them clearly.

Bear in mind, at the time these units were manufactured, specs were still conservative. The two amplifiers had rated power THDs of 0.005%/0.007% and 0.002/0.0007%, so these 'tests' are so many orders of magnitude away, it is ridiculous.

I see no both channels driven testing, FR plots L/R, phono stage testing (overload, sensitivity, S/N etc). The SUV-90D BCD (both channels driven) 8 ohm result is also suspect- it is a single PSU/pair of caps only and the single vs both will be different, just like the BCD 4 ohm result.

The FFT appears to show absolutely nothing harmonically related whatsoever and that doesn't remotely correlate with the power vs THD plot.

Typically, this series of amplifiers and their various iterations, measured extremely well, with no perceptible deviation across the audible bandwidth. In fact most good gear in the late 80s/early 90s was essentially ruler flat. The upper octave rolloff (0.5dB) above 20KHz is also suspect.
 
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elberoth

elberoth

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Well, Technics manual states the FR as +0dB, -0.1dB (20-20kHz) and 0.8-150kHz (-3dB) which is almost exactly what you see in our masurements.

Want lower THD+N levels and ruler flat FR ? Here are the Soulution 710 masurements:

25222-max_soulution710_lab01.jpg


25223-max_soulution710_lab02.jpg


25224-max_soulution710_lab03.jpg



Here are the Soulution 710 measurements from the Stereophile:

811Soulfig1.jpg


The Soulution specs for the Frequency Response are 0 – 1 MHz (– 3 dB), which means that our measurement is actually closer to manufacturer's specs than the Stereophile's.

Measured S/N (A-weighted) is also similar: 96.8dB (Stereophile) vs 98dB (our) vs 107dB (Soulution).

Stereophile's THD+N measurements seem to show slightly lower numbers than ours - 0.004 vs 0.010 @ 1W.

811Soulfig4.jpg


Stereophile Audio Precision may have just better resolution than our Neutrik A2D.

FFT to clean ? How about this darTZeel clone measurement ?

transaudio-fft.png


which corresponds to THD+N:

transaudio-moc.png


That is also very close to Stereophile measurements (original dart, not clone):

DARFIG3.jpg


DARFIG6.jpg


So I wouldn't call those measurements a crap. Unless Strereophile's measurements are also crap.

Here you can browse over 250 measurements of different amps made by my collegue:

https://audio.com.pl/testy/stereo/wzmacniacze-stereo

Hope this helps.

PS. I'm trying to secure the original darTZeel amp to make the comparo. So stay tuned, I will post them in another thread.
 
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elberoth

elberoth

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Measurements like these would lead me to believe they would sound as good a comparable powered current amps.

Any thoughts?

They look OK. Many budget amps (even receivers) measure like this. On the other hand - I know $1000 modern amps (those Technics amps would probably cost $1500-$2000 in 2018 money) in class AB that measure much better.

Of course, proper hi-end amps, like the soulution 710 mentioned, also measure much, much better.
 

cjfrbw

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When my Sony TAN 8550 VFET was done with it's servicing and (partial) refurbishing and recapping, he measured it as 125+124 Watts RMS @8ohms (nominal rating was 100W per channel), before clipping, a figure which surprised even me.

Don't know the distortion, but those were typically measured in the 0.5 to 0.1 percent distortion ranges.
 
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Vintage57

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Measurements like these would lead me to believe they would sound as good a comparable powered current amps.

Any thoughts?


But can we hear the difference in measurement other than when they “screw up”.
 

Sal1950

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Collecting and using vintage gear is so much fun. I really miss the vintage tube gear I had at my pre-retirement digs. Not for any special sound qualities mind you, in most cases they're lacking compared to modern rigs. It's just the nostalgia aspect that warmed my heart. ;)
 

DonH56

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Collecting and using vintage gear is so much fun. I really miss the vintage tube gear I had at my pre-retirement digs. Not for any special sound qualities mind you, in most cases they're lacking compared to modern rigs. It's just the nostalgia aspect that warmed my heart. ;)

And a whole lot more, I imagine, from the tubes... I liked the sound of my old tube gear but have no real desire to return to it. The preamp measured very well indeed but the tube amp didn't do so well with varying loads (did OK on my Magnepans though bass was never as good asa with a big SS amp). Added a LOT of heat to the room.
 

restorer-john

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Stereophile's THD+N measurements seem to show slightly lower numbers than ours - 0.004 vs 0.010 @ 1W.

811Soulfig4.jpg

Measured using Neutrik A2D

index.php

index.php

Huh? Your THD+N at 1 watt on either amplifier is 0.17-0.2% and 0.2-0.25%, stereophile measured 0.004%@1Watt, which is roughly 50 times different. At 100mW 'your' numbers are 80-90 times different to Stereophile's AP numbers.

You also haven't addressed the clearly incorrect SUV90D single channel and both channel figures at 8 ohms. I know that is wrong, the single power supply will produce a higher single channel vs both channels as I too, have been testing and repairing amplifier for nearly 40 years.

If you are going to cut and paste technical reviews you or your colleague have performed in the past, that's fine, but don't expect not to be questioned on minor or major errors. This is, after all a technical site.

Cheers. John
 
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Blumlein 88

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Reminds me of my early HiFi days. I have this 110W/channel Yamaha sitting in storage with no idea what to do with it!

View attachment 12789
Gave my brother the big brothers to this for Christmas way back when. The C2 Control amp and M80 power amp from the natural sound series. Those still work and sound good. Maybe I can borrow it and measure it some time. I remember the C2 had a fantastically quiet and clean phono stage.
 

cjfrbw

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A measurement nerd fight, cool! Only at ASR!
 

restorer-john

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When my Sony TAN 8550 VFET was done with it's servicing and (partial) refurbishing and recapping, he measured it as 125+124 Watts RMS @8ohms (nominal rating was 100W per channel), before clipping, a figure which surprised even me.

Those figures are typical for the TAN 8550. It is a lovely power amp. Did you have the 'death diodes' replaced?
 

cjfrbw

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Yes, the diodes in the driver boards and the power supply were upgraded along with other elements and the power supply capacitor bank replaced.

How's the sound? Exquisite in a word. Using it with a directly heated triode driver stage, nothing I have heard at any high end audio show one-ups it. Mesmerizing.

I have a Yamaha B2 as well, original parts as far as I can tell, and it is the same way, in a word, mesmerizing sound. That is what I always craved from tubes, and it is nice to have it in a SS amp, though qualitatively different (less fluffy harmonics, more incisive, better dynamics in the VFET, but vast, deep and very fast sweet tone nonetheless).
 

Timbo2

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Gave my brother the big brothers to this for Christmas way back when. The C2 Control amp and M80 power amp from the natural sound series. Those still work and sound good. Maybe I can borrow it and measure it some time. I remember the C2 had a fantastically quiet and clean phono stage.

I’d be happy to send it to you. I’ve been pondering putting it back into use and you measuring it would confirm that none of caps likely need to be replaced.
 

Krunok

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The FFT appears to show absolutely nothing harmonically related whatsoever and that doesn't remotely correlate with the power vs THD plot.

Very true - that also crossed my mind when looking at those graphs.
 
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