N.B. I have not measured anything!
The two output capacitors being directly in the audio path would seem to be worth spending a reasonable amount on.
What that sum is depends on the depth of your pockets. It could be polypropylene caps, or silver foil.
The caps will affect the sound in ways that everyone describes differently. Is there a "best?" Well, that's up to your ears.
I use Mundorf MCap evo in mine, bypassed with Russian FT3 Teflons. (because I can.)
Sounds good to my ears. (No, I did not try with and without bypass.)
The caveat is what will fit on the board or in your case. It needs checking with some of the offerings out there.
The two output capacitors being directly in the audio path would seem to be worth spending a reasonable amount on.
What that sum is depends on the depth of your pockets. It could be polypropylene caps, or silver foil.
The caps will affect the sound in ways that everyone describes differently. Is there a "best?" Well, that's up to your ears.
I use Mundorf MCap evo in mine, bypassed with Russian FT3 Teflons. (because I can.)
Sounds good to my ears. (No, I did not try with and without bypass.)
The caveat is what will fit on the board or in your case. It needs checking with some of the offerings out there.
This article / blog has been referenced a number of times. The entire series is worth a read, IMO.
https://www.syclotron.com/why-are-people-obsessed-with-coupling-caps/
Buy / Use whatever brings you the most joy.
Good day, here we go again, I put the BA3 on the side waiting for the hum being addressed and using the AR SP9 in the meantime, today, encouraged by @Zen Mod and by being forcedly off of work, took a mini jack to RCA cable and output a 1Khz sine wave signal from my MacBookAir, max sound output, to my AR SP9 and then checked AC on the output to measure 4.1VAC and then same test with the BA3 and the result been a mere 4.2VAC where I expected a way bigger gain, something must be wrong with either measuring, the BA3 or both...
p.s. I have about 0.4VAC out of the MBAir sound output
p.s. I have about 0.4VAC out of the MBAir sound output
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You're getting a gain of 10 off of the preamps (a good sign).
Your source (the MacBookAir) is low (0.4Vrms instead of 2Vrms) which looks to be the culprit.
Do you have a CD player or other known 2Vrms output source to try?
Your source (the MacBookAir) is low (0.4Vrms instead of 2Vrms) which looks to be the culprit.
Do you have a CD player or other known 2Vrms output source to try?
I got the CD of course but can I measure the output (of the preamp) by playing whatever any CD (maybe some electronic music like house or stuff like that) and repeat same procedure as above (DMM on the preamp main output)?
A couple options:
1. Find or make a test disc with a 1kHz signal then perform the same measurement.
2. Hook it up in the system, play your favourite disc and see if full volume satisfies the ear test.
Poking around for a test disc. post in a bit with results unless someone beats me to it.
1. Find or make a test disc with a 1kHz signal then perform the same measurement.
2. Hook it up in the system, play your favourite disc and see if full volume satisfies the ear test.
Poking around for a test disc. post in a bit with results unless someone beats me to it.
Ah, @6sX7 you mean I should have a CD burner uh?! Only one of the computer has an optical unit, now if that works is a whole different story... might find a test disk, that's no problem.
Loudspeakers are JBL L220, 90dbW/m with the 50W tube amp they can shake the walls :-D
@ItsAllInMyHead yep, seem to recall the CD input has a lower gain than line ones, will play some music through the CD player (glorious Sony X505ES whose DAC sounds waaaaaaay nicer than my ugly Beresford Caiman SEG, that DAC being next thing which has to leave the desk...).
Loudspeakers are JBL L220, 90dbW/m with the 50W tube amp they can shake the walls :-D
@ItsAllInMyHead yep, seem to recall the CD input has a lower gain than line ones, will play some music through the CD player (glorious Sony X505ES whose DAC sounds waaaaaaay nicer than my ugly Beresford Caiman SEG, that DAC being next thing which has to leave the desk...).
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I did an extra random test, picked an old Adcom GFP345 preamp and installed a db meter on my mobile, play Depeche Mode and then same tune but back with the SP9 and the gain is a very tiny bit higher with the latter, it got late now but next time I will check again the SP9 vs the BA3 to find out about the db level, anyway got the feel the SP9 even tho louder sounds thinner if you know what I mean
p.s. literally loosing my mind, playing a CD now and it goes way past 90db vs the average circa 80 of the previous test, will have to find out what's wrong with the DAC/computer combo as this is way loud now!!!
p.s. literally loosing my mind, playing a CD now and it goes way past 90db vs the average circa 80 of the previous test, will have to find out what's wrong with the DAC/computer combo as this is way loud now!!!
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Extra test, playing CD, Mario Biondi, switching from CD to DAC and output volume is about the same (the CD player sounds very much better, smoother), when I play off the MacMini which is wired to the DAC via USB there's quite a loss, at this point little doubt something doesn't work with the MacMini, I have to resurrect a RasPi3+ and use it as a streamer to find out if the same thing happens.
By the way, the F4 thing sounds!!!
By the way, the F4 thing sounds!!!
but success none the less!
Time to enjoy for a bit before tackling the next problem.
btw, have you checked if any software volume controls are engaged and if they have been turned down?
Time to enjoy for a bit before tackling the next problem.
btw, have you checked if any software volume controls are engaged and if they have been turned down?
Great guide - very well put together.
I have a question on the power draw - what transformer VA rating would you recommend?
I have a question on the power draw - what transformer VA rating would you recommend?
The schematic shows 53mA per channel. So round up to 60mA to allow for some current consumed by a regulated power supply.
I would say 20VA minimum would be conservative and even enough if you go for the +/-32V supply, and includes a few Volts dropped by a regulated power supply.
I would say 20VA minimum would be conservative and even enough if you go for the +/-32V supply, and includes a few Volts dropped by a regulated power supply.
Muahaha it LIVES!
Had to rebuild with a new board; salt air near the beach absolutely destroys electronics, including my ten-year old Panasonic plasma (sniff).
I'm going to let the board cook for a bit. I'm only getting 350mV bias (across R10 only) with no offset. I've noticed that they both creep up with time, so I'll give it an hour and play some more.
P1/2 are standard 500 with IRF9610/610 and 2SK170/J74.
Had to rebuild with a new board; salt air near the beach absolutely destroys electronics, including my ten-year old Panasonic plasma (sniff).
I'm going to let the board cook for a bit. I'm only getting 350mV bias (across R10 only) with no offset. I've noticed that they both creep up with time, so I'll give it an hour and play some more.
P1/2 are standard 500 with IRF9610/610 and 2SK170/J74.
Someone here once mentioned being in tropical areas, they seemed to seal electronics with epoxi-stuff precisely for that… no more tinkering afterwards though…