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The BA-3 as preamp build guide
The BA-3 as preamp build guide
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Old 15th September 2021, 05:52 PM   #2191
spryor is offline spryor
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Originally Posted by ItsAllInMyHead View Post
Should work just fine.

I don't see the need for a soft start or the caps, assuming you're using reasonably-sized toroids.
Thanks, IAIMH. I'm using the Antek AS-0520s toroids - 50VA/20V. I figured it probably wouldn't make logical sense for the soft start and safety caps to be required for dual mono but not a single PSU. But, since "rudimentary" would be an overly generous description of my understanding of how all these circuits work, I greatly appreciate you confirming that I'm on the right track!
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Old 16th September 2021, 10:08 AM   #2192
cubicincher is offline cubicincher  Germany
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Default to spryor #2189

Hello spryor,


I have added a pic when I was playing around with the BA-3 FE as a preamp a few years ago (in 2018).
I used groundloopbreakers (CL-60 thermistors) . No CL-60 as inrush current limiter with those small toroids.

On the pic one test is shown (on the wooden test board): dual mono, one small toroid per channel and a symmetrical cap-bank per channel. I've got around + - 28.8 V on the rails. You can easily go up to +-32 V-rails.

I was also playing with different JFets (complementaries), outputcaps....
Later I build a seperated dual mono - PSU with toroids - CLC-filter - voltage-regulators. This BA-3-preamp is still running/sounding very nice! A lot of gain... Have fun building this great sounding preamp!

Cheers
Dirk
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File Type: jpg Pass BA-3 FE 002.jpg (979.0 KB, 278 views)
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Old 17th September 2021, 03:21 PM   #2193
spryor is offline spryor
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Thanks so much, Dirk! It's super helpful to see other builds, so thanks for the pic and insight into your BA-3 FE dual mono configuration. I'll report back once I get mine wired up and (hopefully) running smoothly.
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Old 17th September 2021, 08:16 PM   #2194
amandarae is offline amandarae  Philippines
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Quote:
Originally Posted by BRN View Post
I just need to post that the BA-3 has become my main preamp. It sounds so good with my F2J and Blumenstein Orca full range speakers is so enjoyable to listen to. With my phono as source it sound it is out of this world. My DAC is okay, but the difference between the 2 sources is easily distinguishable.

Bottom line, I was not expecting the difference between my other preamp, that uses tubes, and BA-3 to be that great.
Me too!

I have Type 26, Type 01A, ACP +, and Wayne BA2018 in semi-retirement. I have not put my BA3-FE in a case yet up to now because I am too lazy and it sound amazing as is (of course, you need to find the H2 and H3 balance to your liking first)! Un-believable dollar to performance ratio of investment this piece! I think all audio preamp should have H2 and H3 adjustment as a standard feature
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Old 3rd October 2021, 04:47 PM   #2195
ScottyBe is offline ScottyBe  United States
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The BA-3 as preamp build guide
Hi,
I am pretty new to building. I would like to start the BA-3 build as a preamp next. I have noticed parts for various builds are obsolete and hard to find. Is it possible to still obtain these MOSFETs? 2SJ313 and 2SK2013?
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Old 3rd October 2021, 05:36 PM   #2196
ozorfis is offline ozorfis  Germany
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Maybe Prakit still has some:

FS: TOS 2SK2013/2SJ313

good luck Scotty
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Old 3rd October 2021, 06:18 PM   #2197
ScottyBe is offline ScottyBe  United States
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The BA-3 as preamp build guide
Thank you Ozorfis, I will reach out and see if they are still available.
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Old 4th October 2021, 06:40 PM   #2198
ScottyBe is offline ScottyBe  United States
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The BA-3 as preamp build guide
I have a question on the JFETs. The diy store is recommending 2SJ74 6-8mA and 2SK170 at 8-11 mA. Is it ok to use both JFETs that are 8-11mA or should I buy the 2SJ74 separate at the 6-8mA rating?
Also, can someone explain the difference between the NP Quad and the NP Octet.
Thank you
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Old 4th October 2021, 06:46 PM   #2199
6L6 is offline 6L6  United States
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The BA-3 as preamp build guide
You want

NP Quad (NNPP)
Toshiba 2SK170/2SJ74 Quad Idss 8-11mA - $45

That's (2) pairs of matched K170/J74

An Octet is (4) pairs.
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Old 4th October 2021, 06:55 PM   #2200
ozorfis is offline ozorfis  Germany
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Yass those JFets need to be matched and in the 10mA Idss range.
Here you can get genuine Toshiba parts:

JFets
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