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The BA-3 as preamp build guide
The BA-3 as preamp build guide
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Old 8th April 2020, 04:57 PM   #1801
MEGA_amp is offline MEGA_amp
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The BA-3 as preamp build guide
Default chassis

the link on page 1 for the "galaxy 388" chassis is dead. What is the recommended chassis in the diyAudio store?

thanks
John
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Old 8th April 2020, 05:00 PM   #1802
budwiser is offline budwiser  United States
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Originally Posted by MEGA_amp View Post
the link on page 1 for the "galaxy 388" chassis is dead. What is the recommended chassis in the diyAudio store?

thanks
John
I used the Pesante 2U.
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Old 8th April 2020, 05:13 PM   #1803
6L6 is offline 6L6  United States
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The BA-3 as preamp build guide
Quote:
Originally Posted by Manolo47 View Post
How about 400VA, difference is noticeable! Bigger soundstage and deeper bass.
In a linestage? That would be, well, enormous and heavy. I’d be all for additional PSU filtering before the regulator, but massively oversize transformers seem only to make more magnetic hum issues.


I can’t tell a difference between a 300VA and 400VA transformer in a class-A power amp. YMMV.
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Old 8th April 2020, 07:08 PM   #1804
Manolo47 is offline Manolo47  Puerto Rico
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There is a story behind this. Maybe nostalgic. In the early 80's if I recall right, I had a PSAudio IV full function preamp. It was very good, had a lot of good print at that time.

The story goes that Paul and Stan installed a transformer from an amplifier in a unit they were working or tweaking, though they did not have the stock transformer available.
It was a very big one, suitable for an amplifier. The change for the better in the sound was enough to offer an upgrade for the preamplifier. The PS was an outboard one, so it was easy. I got one. And the difference was impressive. Paul still talks about that adventure in one of his videos. Maybe back then this was a bigger issue because the PS in question was not as sophisticated as the ones used now, you know, regulators, shunts, etc... Allen Wright also mentions this in his book. I had the transformer laying around so I tried it... worked magnificently, no noises, no hum, etc... and as I mentioned I perceived better sound... maybe I'm nostlagic..
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Old 8th April 2020, 11:32 PM   #1805
Zen Mod is offline Zen Mod  Serbia
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The BA-3 as preamp build guide
I tried that too,not once
.......... however impressive approach , massive Xformer plus crude reg is always worse than proper xformer with proper reg
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Old 9th April 2020, 06:06 PM   #1806
analog_sa is offline analog_sa  Europe
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Originally Posted by Zen Mod View Post
massive Xformer plus crude reg is always worse than proper xformer with proper reg
I beg to differ. No rules apply here, some preamp circuits sound better, at least to me, without any active regulation. A few caps, a few (preferably amorphous) chokes is all it takes. And dual mono of course

Recently tried that recipe with 500VA per channel and the result was rather nice. Certainly nicer than a 300VA transformer with separate L/R secondaries + salas 1.3. Of course YMMV.
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Old 9th April 2020, 06:15 PM   #1807
Zen Mod is offline Zen Mod  Serbia
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.....Of course YMMV.
follow that

as I'm sayin' - I always prefer a way which is most rattling my cage

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Old 9th April 2020, 08:32 PM   #1808
MEPER is offline MEPER  Denmark
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To reveal what you like about the different PSU approaches it would be interesting to have an amplifier distortion profile of each approach.
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Old 10th April 2020, 10:23 AM   #1809
analog_sa is offline analog_sa  Europe
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To reveal what you like about the different PSU approaches it would be interesting to have an amplifier distortion profile of each approach.

In the context of preamps (class A) i expect the difference in distortion profiles due to a different PS to be zilch. A design with 0psrr may show some vague dependence, but not very likely if there is sufficient local decoupling.
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Old 13th April 2020, 04:08 PM   #1810
sov is offline sov  Sweden
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The BA-3 as preamp build guide
BA3 is warming up at bias ≈890mV. It sounds very controlled and relaxed with fine details. At 90% bias 1V gives 2.5V out. In a few day I will turn up the bias. The FFTs are done with almost no warming up without tinkering with P3s. 1K/1V sine wave from RCA input, so through a 10K pot at minimum resistance. More testing with full bias. Feets and an indicator led is scheduled.

Thank you 6L6 for bildguide, NP for a nice design and everyone else for tributing.
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File Type: jpg BA3_F4.jpg (175.3 KB, 236 views)
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