CHANGSTAR: Audiophile Headphone Reviews and Early 90s Style BBS

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Author Topic: EHHA (non-A) tweaks, tips etc  (Read 2268 times)

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omegakitty

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Re: EHHA (non-A) tweaks, tips etc
« Reply #10 on: June 11, 2012, 09:53:21 PM »
Quote from: rhythmdevils on June 11, 2012, 09:49:24 PM
Has anyone noticed this amp being more sensitive to the build or components than others?  Because the two EHHAreva's I heard were very different sounding.  I didn't get to compare them side by side of course, but my sonic impressions were totally different, if I didn't know better I would have guessed they were different amps all together.

My best guess is it could be feedback related?

Though it's just a guess. I did see your posts at the end of the rev A thread, I guess it was never resolved?

(lots of guessing in this post  :P )

One more build related question: given the current draw I take it an 80 VA transformer should be ok for the +/- 30v DC amp supply?
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sachu

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Re: EHHA (non-A) tweaks, tips etc
« Reply #11 on: June 11, 2012, 10:10:32 PM »
yes, that should do plentifully.

I'd run the heaters in parallel, i.e at 6.3Volts.

Triads are easy enough to find or can pick one at ratshack for about 10-11$.
« Last Edit: June 11, 2012, 10:12:29 PM by sachu »
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dBel84

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Re: EHHA (non-A) tweaks, tips etc
« Reply #12 on: June 12, 2012, 04:15:28 AM »
Quote from: omegakitty on June 11, 2012, 09:27:39 PM
WRT to the open loop gain/NFB, will the amp sound more linear with a touch higher NFB?

I forget the numbers but stock recommendation was best to my ears, I tried everything from maximum feedback ( 10Kohm iirc ) to no feedback ( no resistors ) and the range ( again iirc ) was 30k - 100K .

BUT I would try several to find what suites your system and preferences best.

..dB
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sachu

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Re: EHHA (non-A) tweaks, tips etc
« Reply #13 on: June 12, 2012, 04:58:48 AM »
The default 30k is a good place to start.
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gurubhai

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Re: EHHA (non-A) tweaks, tips etc
« Reply #14 on: June 12, 2012, 05:41:36 AM »
Ya, the default setting was fine to my ears as well.

For heater supply, I just populated the rev. A's heater supply on a perfboard.
Simple & cheap. :)
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32y0

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Re: EHHA (non-A) tweaks, tips etc
« Reply #15 on: June 12, 2012, 09:45:14 AM »
I also like the default setting the best on the rev A I have built (mosfet).
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omegakitty

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Re: EHHA (non-A) tweaks, tips etc
« Reply #16 on: June 15, 2012, 07:00:34 PM »
Received the kit and boards were smaller than I expected which is really nice since this will be a desktop amplifier at work and every bit of desk space counts.

I'll start work on this after finishing the LME49600 amp similar to The Wire.
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omegakitty

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Re: EHHA (non-A) tweaks, tips etc
« Reply #17 on: June 16, 2012, 12:01:46 AM »
I also have a pair of EHHA I boards, (not populated) I'll let go for cheap if anyone is interested.
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