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TECHNICS SU-V8X modded Saken finals

Synchro-bias

Synchro-bias

New ClassA
wjys8h.jpg


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Video of the V8X - her name i adopted is "Dusty":music::banana:
http://www.youtube.com/watch?v=mg-PGeo0Nd4


INFO on the TEchnics V8X below
Technics SU- V8X 1983 - 1985
Computer Drive New Class A
Syncro Bias
4 x 8200uf low ESR (Equivalent Series Resistance) electrolytic capacitors
Power Transformer with OFC wire in a case of heavy magnetic sheild of special resin to reduce vibration
High Quality Source Straight DC

Specs:
Power Output: 150 w (6ohm) 0.005 %
120 w (8ohm) 0.003 %
Total Harmonic Distortion: 0.002% (20Hz ~ 20Khz, rated output -3dB)
Power bandwidth: 5Hz ~ 100kHz (THD, 0.002%, 8ohm)
Dimensions: 430w 141.6h 380d
Weight: 12.8 kg
Power: 670w

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I guess I'm confused. What's the mod- different output devices and what else? I notice that Group Two is quoting power differently than Matsushita does, so those numbers may not compare.
 
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Hello Pacific Stereo,
I am a bit confused also but my friend explained again.
The SANKEN Output Transisters the 180W is easily attained in 4 ohm speakers on 8 ohm tap (spkr sw on back) This is alowwed now because of the massive output stage that is 400W capable. The other mod is the gold speaker terminals, Supra Lorad2.5 mains power cable.

Hello Ecluser.
The 80A is the output stage capability that this ultimately means, if a speaker goes short, your amp will not blow up

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http://www.sanken-ele.co.jp/en/prod/semicon/pdf/2sa1494e.pdf
 
ive seen Harman/Kardon use one set of 2SC2921/2SA1215 with 40A capability, the 17A is CONTINUOUS max @ 25deg C - 4 per chan will provide a stable 400W/34A per chan by the books, driven on low impedance ive seen some massive current readings out of these in various setups - all in all, this setup against what was in there runs cooler (a definate good thing) and has been proven to be far more robust under adverse load conditions.
 
Very nice SammyMac. Been a long time how have you been? Looks like something I may want to do to my SU-V10x. Have you been able to notice any sonic differences since the upgrade?

Bill
 
Hello Pacific Stereo,
That is one channel, 4 on the otherside - all up 8.

Hello Baily
Runs cooler, that is for sure.

Hello Bill
I know i have to be more active. Ive ben pretty fine and yourself? :D
I think Baily has a V-10X, not sure if its been modded. Sonic differences in clarity? I dont know but I find with the extra power, it has a nice strong presence in the sound. It runs cooler, which is good considering the summers we have here in my part of Australia. Btw, a beautiful amp the V-10X :D
 
under less than desirable loads the sonic integrity is more stable, i have pushed these into half ohm load after doin the same test on the original and the waveform was definately more linear with the new outputs. - under normal conditions this amp will last for eons, i have quite alot myself, and if doing parties, i never feel worried about electronic issues, even if speakers lose impedance (after some partygoers crank it up and partially cook the coils or totally barbecue them into shorts. the emitter overcurrent detect kicks in, and blown outputs i have not seen in any of my improved amplifiers. one test i did on a H/K amplifier was to frive it into a total short (with protection overriden) the outputs never faultered - the pcb track from the resivoir cappies blew out bigtime, upon its repair, youd have never have known it had endured this, all waveforms were well within specifications.
 
SammyMac said:
Hello Pacific Stereo,
That is one channel, 4 on the otherside - all up 8.
Click to expand...

Something sounds strange here - you picture shows 4 output transistors pr channel, rated at 17Amp - you have 2 x 17A at positive, and 2 x 17A at negative - that's 34Amps - not 80.
 
EDIT: Original incorrect. But 34 amps of current capability does make for a robust output stage not likely to blow up. Cool. Did they upgrade the emitter resistors, too?
 
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I just don't get enough coffee- I was right the first time. Max current per channel is 34 amps with four 17-amp devices. The signal is ALTERNATING, and can't be both positive and negative simultaneously. Duh.
 
avionic said:
Enough to do at least 2 amp assemblies on that one heatsink.:D
Click to expand...

If enough is good, moar must be better.

PacificStereo said:
I just don't get enough coffee- I was right the first time. Max current per channel is 34 amps with four 17-amp devices. The signal is ALTERNATING, and can't be both positive and negative simultaneously. Duh.
Click to expand...

Anyone notice those are the same (sub) outputs used in a Yamaha M-80, and the M-80 has 158,000uf of PS cans and 2 transformers to work with... :scratch2:

Where's all the power coming from? It isn't in the outputs. :D
 
PacificStereo said:
I just don't get enough coffee- I was right the first time. Max current per channel is 34 amps with four 17-amp devices. The signal is ALTERNATING, and can't be both positive and negative simultaneously. Duh.
Click to expand...


If the picture is magnified - it certainly looks like there are 8 output transistors pr channel :

attachment.php


It looks like they are mounted back to back - that is the metal on one transistor, against the metal on the other - then they attached to the heat sink -

How on earth do they expect the output transistor that is attached to the heatsink to be able to transfer the heat from the outer transistor to the heat sink through the transistors housing ??
 
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PacificStereo said:
Yeah, if you look at the other photo, there clearly are only 4 devices.
Click to expand...

please all .... if you look carefully at the heatsink closest to the transformer ... i'm convinced i can se a thin white line, and the angles on the transistors

attachment.php


it's not a mirror from the heatsink :)
 
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