Those are some monster coupling caps. The board looks much better with the rest of the components the right size.
I know the idea that caps have a "sound" is controversial, but there is a distinct difference in sound when the coupling caps are removed completely from my Pearl 2. Therefore, in my mind caps do have a sound.
I figure $32 or so for 4 audiophile caps isn't too crazy, considering one can spend several hundred on each at the high end. Also, I'm stuck at home and need stuff to do.
Doubts in the start-up of the preamplifier.
Hi. I am assembling a BA-3 preamplifier and I am running tests, and I have some doubts.
Add that I'm a newbie and I can ask a lot of silly questions.
1.- DC measurement is made between ground and before the capacitor, why?
2.- The right channel I have the following measurements: R10-R11 960mV.
DC 4.5mV (after capacitor and ground) and 0.8mV (before capacitor and ground).
3.- The power supply is a Chinese copy of Sigma22, but it seems very stable. Would it be interesting to have one source for each channel? I ask this question because the left channel I do not like the first test I have done.
4.- If I have 100mV DC at the preamp output, can they cause any problem in the amplifier? Indicate that I use a First Watt F5.
5.- When I make the measurements in the left channel, I will be adding new posts according to the doubts that come to me.
Thank you.
Hi. I am assembling a BA-3 preamplifier and I am running tests, and I have some doubts.
Add that I'm a newbie and I can ask a lot of silly questions.
1.- DC measurement is made between ground and before the capacitor, why?
2.- The right channel I have the following measurements: R10-R11 960mV.
DC 4.5mV (after capacitor and ground) and 0.8mV (before capacitor and ground).
3.- The power supply is a Chinese copy of Sigma22, but it seems very stable. Would it be interesting to have one source for each channel? I ask this question because the left channel I do not like the first test I have done.
4.- If I have 100mV DC at the preamp output, can they cause any problem in the amplifier? Indicate that I use a First Watt F5.
5.- When I make the measurements in the left channel, I will be adding new posts according to the doubts that come to me.
Thank you.
1. The capacitor is there to filter out any DC.
2. Those measurements are fine, the schematic says 1V for R10 and R11. .8mV between R12 and C3 is good, not sure why you have some DC after the cap but it's a tiny amount.
3. No need to have two power supplies but it's a matter of choice if you want to go dual mono.
4. 100mv DC after the coupling cap doesn't sound right.
Hikari, as to answer #4, I posted this as a concern over in the Wayne's 2018 line stage thread. My concern was a small amount of DC on my build of that LS that could then be amplified and sent to speakers.
I was told by more than one member here that not worry, the amplifier cant amplify the DC. Maybe that was different b/c that was a separate front end and here it is in the front end of the amplifier? There is a lot that I dont comprehend with all this, but for some reason I believed it so.
I think it was in some thread somewhere about building F5 in that it was capacitorless so DC coupled.
I thought the understanding was at that time, at least to me that if your preamp went south and released a bunch of DC, it would go to amplifier, be amplified and cook speakers. Maybe it was in the Mesmorize/Hypnotize threads, as they were DC coupled.
I'm also a bit puzzled as you were, about him having larger amount of DC after cap than before cap. Wondering if his measurement of "before the cap" was before the cap, or on the other end closest to edge of board? Dont see how a cap would increase DC?
If amp doesnt amplify that DC why is everyone concerned with it? I know I always was. My understanding of all this, or lack of understanding may be the problem here!
More confused as ever, S.N.A.F.U. for me,
Russellc
I was told by more than one member here that not worry, the amplifier cant amplify the DC. Maybe that was different b/c that was a separate front end and here it is in the front end of the amplifier? There is a lot that I dont comprehend with all this, but for some reason I believed it so.
I think it was in some thread somewhere about building F5 in that it was capacitorless so DC coupled.
I thought the understanding was at that time, at least to me that if your preamp went south and released a bunch of DC, it would go to amplifier, be amplified and cook speakers. Maybe it was in the Mesmorize/Hypnotize threads, as they were DC coupled.
I'm also a bit puzzled as you were, about him having larger amount of DC after cap than before cap. Wondering if his measurement of "before the cap" was before the cap, or on the other end closest to edge of board? Dont see how a cap would increase DC?
If amp doesnt amplify that DC why is everyone concerned with it? I know I always was. My understanding of all this, or lack of understanding may be the problem here!
More confused as ever, S.N.A.F.U. for me,
Russellc
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