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Old 17th April 2014, 12:20 PM   #1
webby is offline webby  United Kingdom
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Location: england
Default TPA3116D2 and 6N3 pre build

Hi All,
I have started a integrated amp based on the YG 3 tube 6N3 + Blue 2.0 3116 PCB.
My toroidal transformer has 2 x 18volt 3.3A secondaries to use as 6.6A parallel and I have a pair of 5 Amps voltage regulator modules, based on National Semiconductor LM338T. at 19VDC
http://www.ebay.co.uk/itm/2010554114...84.m1439.l2649

I have also ordered Wholesale Product Snapshot Product name is Type 21 Step potentiometer progressive potentiometer dual 50k Without foot semi-circular handle 20MM for HIFI
21 Step potentiometer progressive potentiometer dual 50k volpot, not wired up yet.

The chassis is from modu
I think you can buy them from the DIY Audio shop if not in europe.

2 X Russian 6n3p-Ev fitted

So here is my problem..
If I have the 3116 running direct from my phone as a source, its silent with no hum. As soon as the Pre is connected, I get hum. I have changed the valves, tired RCA cables between the pre and 3116 and I have soldered directly a 3 pin cable to the bottom of the pre outs. I have tried wiring the PCB GND ( this is marked GND on the bottom of PCB 160 0 160)to the chassis earth directly and via an X2 cap & 150R resistor.
Still hums and I am unsure what to try next?
Any ideas?

Many Thanks
Ian
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Old 17th April 2014, 07:33 PM   #2
xrk971 is offline xrk971  United States
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It is probably a ground loop from your preamp to the 3116. Isolate the power supply ground from preamp and 3116. Also, is preamp power source from transformer clean? Ripples on that may be getting picked up on input of 3116. Only other thing is to consider using balanced driver buffer.
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Old 19th April 2014, 04:43 PM   #3
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Hi,

I already done this architecture with the YJ blue board, and a matisse clone 6N3.
For me, it changes a little bit the sound, mainly the low frequencies (bass) , but it is not better or bad. Just a little bit different.
It does not reduce the issues with YJ 3116 : the high frequencies sounds bad.

But maybe you will feel differently the result.
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Old 21st April 2014, 09:47 AM   #4
webby is offline webby  United Kingdom
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Quote:
Originally Posted by xrk971 View Post
It is probably a ground loop from your preamp to the 3116. Isolate the power supply ground from preamp and 3116. Also, is preamp power source from transformer clean? Ripples on that may be getting picked up on input of 3116. Only other thing is to consider using balanced driver buffer.
HI All,
Thanks xrk971, it was a ground loop.
Sometimes its good to have a second mind approach a problem

I have finished the amp.

It has three inputs, 21 Step potentiometer progressive potentiometer dual 50k Volpot that sound better then my Alps blue and has a nice action.
Retro red LED fed from the LM338reg PCB, 6.6A transformer.
Russian 6N3EV valves.
Chassis damped with heavy rubber matting.

So far I am very pleased with the sound, very clean. It needs a few hours of burn in before knowing in full.

Many Thanks
Ian
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