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ε12 shuts off, even with altered values for R5-R8, C5

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ε12 shuts off, even with altered values for R5-R8, C5

Postby salavat » September 30th, 2018, 2:04 am

Hello,

I have ε12 v 1.2, after playing around I increased R5-R8 values to 47K, C5 to 3.3 uF. My epsilon board used in balanced beta setup (one case for amp and power supply). Gain is 5X for all boards

In case of increasing volume rapidly (I use relay switched attenuator) and using high load cans (such as HD800) which require significant level of volume e12 shuts off.

I measured extensively DC on output jacks (UT181a is used for that), DC is around 0, amplitude on each channel os about 2 mv, so I pretty sure there is DC of significant level which might cause e12 shut off.

Any ideas what to do next?

Thanks!
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Re: ε12 shuts off, even with altered values for R5-R8, C5

Postby amb » September 30th, 2018, 11:50 am

Maybe you need to tweak VR1 a little bit.
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Re: ε12 shuts off, even with altered values for R5-R8, C5

Postby salavat » September 30th, 2018, 1:34 pm

Thanks for reply. Can you explain how to tweak it? Now DC offset is about 1.5 mv to either pair of boards...
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Re: ε12 shuts off, even with altered values for R5-R8, C5

Postby amb » September 30th, 2018, 1:43 pm

The instructions are at the ε12 website.
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Re: ε12 shuts off, even with altered values for R5-R8, C5

Postby salavat » September 30th, 2018, 1:56 pm

That is what I've done already, including increased values for resistors and C5. Shut offs still happen on high levels of output.
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Re: ε12 shuts off, even with altered values for R5-R8, C5

Postby amb » September 30th, 2018, 3:59 pm

If VR1 is adjusted properly and you're still encounting false triggers at high playback volume, then you probably need to further increase the value of R5-R8.
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Re: ε12 shuts off, even with altered values for R5-R8, C5

Postby salavat » September 30th, 2018, 4:03 pm

OK, thanks. What would be next level from 47K?
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Re: ε12 shuts off, even with altered values for R5-R8, C5

Postby cobretti » October 1st, 2018, 7:14 am

Is the DC offset level before the relay switched attenuator low?
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Re: ε12 shuts off, even with altered values for R5-R8, C5

Postby salavat » October 1st, 2018, 9:51 am

Yes, but I am pretty sure it does not change. I checked DC offset with input shorted, it stays more or less the same.
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Re: ε12 shuts off, even with altered values for R5-R8, C5

Postby salavat » October 3rd, 2018, 5:08 pm

amb wrote:If VR1 is adjusted properly and you're still encounting false triggers at high playback volume, then you probably need to further increase the value of R5-R8.


Could you recommend values for resistors?
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