Sony V-FET TA-8650::: sound goes "in and out" - diyAudio
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Old 30th March 2005, 09:22 AM   #1
Tek1 is offline Tek1  United States
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Default Sony V-FET TA-8650::: sound goes "in and out"

I have a Sony TA-8650, it sounds great most of the time but about 30 minutes or so after i turn it on and start listening the sound will either suddenly fade out or it will get some nasty sounding distortion. Blasting the music will occasionaly bring it back. I normaly turn it off for a little while (the longer the better it seems). The distortion is in both channels and is audible through the headphone jack as well. I am also running the signal into the power amp input, bypassing all eq's and whatnot. Does anyone have an idea as to what it could be?
TIA

DM
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Old 28th March 2013, 06:09 AM   #2
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Default tek 1 v-fet problem with sound in and out

The sony TA-8650 is approaching 38 years old , I have had 3 of these amazing amps , and I amanged to get another recently , after foolishly selling or swapping them years ago ! I had a similar problem with this bew aquisition , whereby the amp would run either left or right channel , or sometimes both , and also had a lot of cracking on turn on , after much cleaning , and contact cleaner to no avail , I was flicking all the switches up and down convinced it was a dirty switch problem , when all of a sudden , flicking the mute switch awoke all channels , and it's now running perfectly , no noise , no dropping of channels , I would check your amp switches by flicking them all , particularly the mute switch , and it could resurrect your amp again , it's surely worth a try ! Sean
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Old 28th March 2013, 08:04 AM   #3
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There seems to be alot of interest in these Sony V-fet amps recently , and I see people from all over the US and UK looking for them , they are also in demand in Australia , my home base . They are differnet in lots of ways to convential a-b amps , in that they run very hot [ normal ] although mine doesn't get all that hot , just warm . They can sound very smooth , especially after about 30 minutes running , allowing them to warm up , the sound is noticeble by its valve amp sound , very smooth , with great depth and detail , and awesome attack , especially on quality discs . You listen into this amp , and there is great ability to see the sound stage and performers with uncanny accuracy , A word of caution , these amps need good ventilation , and if not you will be tripping the overload switch regularly , as the amp attempts to protect it self from thermal overload ! This one very easy amp to listen to, it has very low distortion at normal listen levels , and has a power band width out to 70k !!!!! So it will outperform a lot of newer so called digital amps on things like super cd and dvd , It even has both input and out put clipping indicators , so you can see if you are overloading the inputs at a glance , it was a very advanced amp in its day , and was compared to many top line American and European pre and power amp combinations , and it beat quite a few with that V-FET sound , the powerfull bass performance and detail will still make you sit up and take notice !
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Old 29th March 2013, 11:09 AM   #4
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Dear Yamahear , it's great to see another V-FET enthusiast , whether it's Sony or Yamaha , they are both premuim products in their day , I was fortunate to be able to be around during the Accuphase / Harmon Kardon / Phase Linear years , I worked in Running a Hi Fi specialiast shop , and I had lots of opportunities to compare amps , both integrated and Seperates thru our Celestion /Mission / Dalquist dq-10's and Quads , KEF's ect , and I always went back to the V-fet sound I have again . I did at one stage have a Yamaha c-1 and b-2 power amp , I recall that combo as another of my favourites ! I did find however that V-fets don't like Electrostatics [ Quads ] and It was difficult to get a full bodied sound out of the Dalquists , I prefered the big Celestions in those days , now I use JBL s310 mk 2's , not the best , but fine for me , I am not a stereo snob , I always give good gear a chance !
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Old 29th March 2013, 04:26 PM   #5
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Quote:
Originally Posted by sean roberts View Post
Dear Yamahear , it's great to see another V-FET enthusiast , whether it's Sony or Yamaha , they are both premuim products in their day
Hi Sean - I didn't want to jack this thread so I pulled my post before you responded ... but since you did here's what I said originally:

Quote:
Originally Posted by sean roberts View Post
There seems to be alot of interest in these Sony V-fet amps recently
I can understand why. I don't have a Sony V-FET amp myself and in fact I've never had the pleasure of hearing one of those but about 10 years ago I came across a good deal on a Yamaha B-2 V-FET amp that needed some TLC I knew I could give it. Before it I owned several different BJT amps that I enjoyed very much and I was somewhat skeptical that I'd truly hear a difference. After only a few hours with the B-2 I realized that there really was something to what people were saying about these wonderful amps and since then, because I enjoyed it so much, I found yet another B-2 that I reconditioned as a backup; sadly, as everybody knows finding spare outputs for these and the Sony V-FET amps is otherwise next to impossible.

Then last fall I came across a sweet deal on a banged up Yamaha B-1, dare I say it, the king of vintage V-FET amps. It had spent its life as a bar amp and was in pretty rough shape cosmetically and electronicaly and was well on its way to becoming a serious boat anchor. I took my time and DIY'ed it back up to spec even going so far as laying out a drop in board to replace the 15,000uF main power supply dual caps that are known to become a problem over time and impossible to get, with some modern 18,000uF 105 C caps.

As you say, there's an added realism in the quality of the depth and detail in the sonics of V-FET amps as compared to their BJT brothers. To my ears it's kinda subtle in that it doesn't jump out at you instantly like night and day ... and some would argue whether or not that difference is really worth the dollar differential between them. That said, I know I'll never rotate these out of my listening setup and I'm happy to have preserved a couple of pieces of audio history in the process.

Quote:
, I was fortunate to be able to be around during the Accuphase / Harmon Kardon / Phase Linear years , I worked in Running a Hi Fi specialiast shop , and I had lots of opportunities to compare amps , both integrated and Seperates thru our Celestion /Mission / Dalquist dq-10's and Quads , KEF's ect , and I always went back to the V-fet sound I have again . I did at one stage have a Yamaha c-1 and b-2 power amp , I recall that combo as another of my favourites !
Again, I can understand why.

Quote:
I did find however that V-fets don't like Electrostatics [ Quads ] and It was difficult to get a full bodied sound out of the Dalquists , I prefered the big Celestions in those days , now I use JBL s310 mk 2's , not the best , but fine for me , I am not a stereo snob , I always give good gear a chance !
This is good to know because I have a pair of ESL-57s in the rebuild queue. Given that they have such a broad impedance vs. frequency curve, down to ~2Ω and a 40 V p-p arch threshold, I've already been thinking that I'll keep the NS-1000M connected since they sound so good and both the B-1 and B-2 drive them effortlessly.
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Old 30th March 2013, 09:34 AM   #6
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There's a Sony TA-8650 for sale on ebay now for 3,500 euros. Amazing.
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Old 30th March 2013, 09:40 AM   #7
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Default Yamahears NS 1000's

Well I have to say I was really happy to read that you have a pair of Yamaha NS-1000's I assume all black with YAMAHA in silver on the front baffle ! These ar truly great speakers , and I recall I had hundreds of hours of enjoyment with mine , at the time , I was driving them with another amp , and not my V-FET , it was a SANSUI au 20,000 integrated , which had huge power , it was part of the DEFINITION SERIES OF Sansui amps , the others being the CA2000 and the BA 2000 and BA4000 power amps . I sold the AU20,000 and then bought my first Sony 8650 v-fet , Although the rated power of the Sony was less , [ 160 rms into 8 ohms 20-20,000hz , the Sony seemed to deliver deeper and more powerful bass at 80 rms same measurements ], but was also dramatically faster , and with more detail too , I have to say , I would like to get another pair of NS-1000 monitors , they were actually used by the BRITISH BROADCASTING CORPORATION as Studio Monitors for many years , Yamaha made some awesome gear , and they proved that many times ! Enjoy those NS-1000 's my friend , hope to hear back soon !
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Old 30th March 2013, 09:54 AM   #8
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Default triplej and this v-fet for sale on ebay at 3500euros

Triple j , this would have to be a mint amp for that kind of money , I think a EURO is about 60 cents , that means they want about $2200 usd !!!!!!My own TA-8650 IS UNMARKED AND IN TOP CONDITION , if I was selling it , I would maybe get $800- $1000 usd if I held out , for someone who really wanted it ! [ I wouldn't sell mine anyway ] After owning three of these amps , I tried lots of others , but came back after much searching to my current 8650 v-fet , I have seen some as low as $500 , but this would be a dicy propostion , recently a guy in Dorset UK , sold one for 500 british pounds , [ about $900 usd ] Try to get one if you can , or a Yamaha V-fet , as Sony and Yamaha were the best exponents of these amps ....best of luck Tripl J .
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Old 30th March 2013, 10:08 AM   #9
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other way... thats about $4,300 AUD! I'd be very interested to hear one but not $4,300 interested!! In fairness it did say it has the original packaging (which is impressive) but i cant imagine it would make it sound better ;-).
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Old 30th March 2013, 10:37 AM   #10
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Triple J , I see you are in Australia , [ $4,300aud ?] I live in Perth WA , I think you could get an 8650 locally in Australia , much cheaper than that , I did see one for about $600aud on GUMTREE , I have no idea what sort of condition it was in , You have to be really carefull with these older amps , I am lucky in that I sold mine origonally to its first new owner , He was my source for my amp , and it has only had a sticky MUTE switch in all of it's 38 years !!!!! So much for old amps being unreliable ! Just use a good anti surge cube like MONSTER , and it will survive ! Besides , these are the best sounding amps around , and many people are on the look out for them !
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