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The BA-3 as preamp build guide
The BA-3 as preamp build guide
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Old 14th October 2018, 10:35 PM   #1141
Zen Mod is online now Zen Mod  Serbia
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The BA-3 as preamp build guide
gain measured ?
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Old 14th October 2018, 10:42 PM   #1142
Twst is offline Twst  Norway
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gain measured ?
Great idea!
0.7v in to 48v out

Should be about 36db if the calculator is correct.
Maybe its just ment to hiss when beeing a preamp
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Old 14th October 2018, 10:46 PM   #1143
MEPER is offline MEPER  Denmark
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That is a lot of gain…...hopefully too much…...even for a MoFo with no gain…..this will be too much…..
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Old 14th October 2018, 11:07 PM   #1144
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The BA-3 as preamp build guide
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Originally Posted by Twst View Post
Great idea!
0.7v in to 48v out

Should be about 36db if the calculator is correct.
Maybe its just ment to hiss when beeing a preamp
so , that's the reason for hiss - way too much gain , while you need 12db or so for your needs

you made some systematic mistake (meaning both channels ) - most probably having wrong or mislabeled resistor in some position

recheck everything, report back
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Old 14th October 2018, 11:17 PM   #1145
Twst is offline Twst  Norway
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Great! I will tear it down looking for answers. The resistors came out of the same bags for both channels, so guess thats the reason for the systematic mistake..
I will report back another day, so don't wait up!
Thanks again!
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Old 14th October 2018, 11:47 PM   #1146
Twst is offline Twst  Norway
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I did infact take a few pictures during construction.
Can't seem to find anything wrong with the written values on the resistors. Guess there could be mislabeling, and then my best bet will be to lift resistors one by one till I find them?

Anyone with a stock but quiet one made gain measurements?
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Old 15th October 2018, 12:05 AM   #1147
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The BA-3 as preamp build guide
regarding gain = from stock values , expect something as 10-ish gain .... which is around 20db

patience , my dear Watson ..... measuring and magnifier time
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Old 20th October 2018, 12:09 PM   #1148
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So I lifted one leg of every resistor, measured and checked with the schematics. All the values are spot on as expected after rechecking the print on all the resistors.
Still not found my excessive gain problem
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Old 23rd October 2018, 04:28 PM   #1149
jphabc54 is offline jphabc54
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My BA-3 build is coming along nicely. PSU is complete and tested. I'm ready to wire up the board.

I'm curious how other builders have managed their grounds on the amp board.

Since there are only two dedicated ground pads on each channel--but a need for at least three grounds per channel (signal in, signal out, and PSU) plus a fourth for the recommended 100k resistor from the output cap to ground--are people splicing into the two available pads or just attaching elsewhere on the board's ground path?

I guess there are actually three vacant ground pads with the C3 electrolytic pads vacant, but I haven't seen pictures of folks using that option.

Thanks!
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Old 24th October 2018, 03:11 AM   #1150
Hikari1 is offline Hikari1  United States
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Originally Posted by Twst View Post
So I lifted one leg of every resistor, measured and checked with the schematics. All the values are spot on as expected after rechecking the print on all the resistors.
Still not found my excessive gain problem
Where are your mosfets?
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