by changing the Aleph J with the BA3 I noticed a sensible (pretty big) drop in the volume, of course at the same volume setting of the preamp BA2018.
In order to align the sensibility (increasing it) of the BA3 to that of the AJ,
have I to change the value of resistors R5, R6, R7 (in the gain stage) or other?
Thank you,
In order to align the sensibility (increasing it) of the BA3 to that of the AJ,
have I to change the value of resistors R5, R6, R7 (in the gain stage) or other?
Thank you,
The BA-3 should have more gain than the J. Or did you susbstitute some of the values of you BA-3 gain stage while building?
thank you
Hugz and kizzez,
Andy
then I have done something wrong... I'll check the components on the gain board
Good Question .
The Single Ended output stage I've prototyped , Vout = 0 ---> + 50mV of drift , as the amp warms up .
So think it would be best to let the amp warm up , and then fine tune the P101 trimmer .
Embarrassing Question .
For the Single Ended output stage , I can't find a reference on why R131 is in the CCS , and do you calculate its value ?
.
Just for clarity.... When you say gain of the BA-3 amplifier is 15dB, the gain is from the front end only and the output stage is just a follower (like the F4). So total gain ~15dB as the BA output stage adds no gain.
Also, BA-3 front end, does it benefit from regulation or is it dead silent when supplied off the main PSU rails?
Thanks
Correct. The BA-3 front end supplies all the voltage gain. The "BA-2" complimentary output stage is very close to the F4.
6L6 and others will almost certainly chime in re: their noise level. In the interim...
To me a measurement is about the only meaningful way to convey "noise". I don't know what speakers you have or what you consider "dead silent". I measure (note my set up is not lab quality) <100uV of noise on the outputs with no load and inputs shorted. It is "dead" silent enough for me with 95dB / 1W / 1m speakers with my ear pressed to the grills. I used the "basic" DIYA Universal PSU boards with nothing special as far as components => normal CRC filtering, discrete regulators, etc. My front end runs from the same supplies as the output boards.
More info if it's of interest.
It is dual mono with Antek shielded transformers and a physical shield/can for each donut. My wire management is OK, but certainly not A+. I chose to keep some wiring longer than necessary b/c I move things in and out of my chassis a lot. Moving the transformers vertically to the front and running the mains wiring between the perforated plate and base plate had the largest effects on hiss / output noise in my build when measured with the patented @pfarrell earbud testing methodology. It's also in a 4U/500 chassis, so the physical distances likely help also. I don't know if it affects output noise / hiss, in any meaningful way, but both supplies have input snubbers. There are probably pics of it somewhere in the thread. My guess is that decent wire management, build layout, and a few other things might bring more benefit than regulation for keeping things quiet. Not saying a separate regulated supply won't provide benefits, but my guess is that would be only after other parts of the build were 'optimized'. My guess is that regulation on its own should not really affect audible noise (against just a good unregulated supply with CLC filtering as an example). However, I am curious how regulating the PSU for the front end vs.output boards and running separate supplies might work out. However, when people discuss "silence" vs. having audible hiss/hum, I have never seen a recommendation to change to a regulated supply (even in the pre-amp thread). Most recommendations surround physical placement of parts and wire management along with grounding schemes. Not saying someone hasn't recommended a regulated supply specifically to address noise, just that I have not seen it (or can't remember it). 🙂
Looking forward to hearing others' opinions / facts. Mine is all opinion and one set of measurements from my build. YMMV.
My
6L6 and others will almost certainly chime in re: their noise level. In the interim...
To me a measurement is about the only meaningful way to convey "noise". I don't know what speakers you have or what you consider "dead silent". I measure (note my set up is not lab quality) <100uV of noise on the outputs with no load and inputs shorted. It is "dead" silent enough for me with 95dB / 1W / 1m speakers with my ear pressed to the grills. I used the "basic" DIYA Universal PSU boards with nothing special as far as components => normal CRC filtering, discrete regulators, etc. My front end runs from the same supplies as the output boards.
More info if it's of interest.
It is dual mono with Antek shielded transformers and a physical shield/can for each donut. My wire management is OK, but certainly not A+. I chose to keep some wiring longer than necessary b/c I move things in and out of my chassis a lot. Moving the transformers vertically to the front and running the mains wiring between the perforated plate and base plate had the largest effects on hiss / output noise in my build when measured with the patented @pfarrell earbud testing methodology. It's also in a 4U/500 chassis, so the physical distances likely help also. I don't know if it affects output noise / hiss, in any meaningful way, but both supplies have input snubbers. There are probably pics of it somewhere in the thread. My guess is that decent wire management, build layout, and a few other things might bring more benefit than regulation for keeping things quiet. Not saying a separate regulated supply won't provide benefits, but my guess is that would be only after other parts of the build were 'optimized'. My guess is that regulation on its own should not really affect audible noise (against just a good unregulated supply with CLC filtering as an example). However, I am curious how regulating the PSU for the front end vs.output boards and running separate supplies might work out. However, when people discuss "silence" vs. having audible hiss/hum, I have never seen a recommendation to change to a regulated supply (even in the pre-amp thread). Most recommendations surround physical placement of parts and wire management along with grounding schemes. Not saying someone hasn't recommended a regulated supply specifically to address noise, just that I have not seen it (or can't remember it). 🙂
Looking forward to hearing others' opinions / facts. Mine is all opinion and one set of measurements from my build. YMMV.
My
(Chiming in…)
🙂
Yes, the front-end has the gain, and the output stage is a follower. (BA complimentary output stage is an F4 without the Jfet buffer)
Will the front-end benefit from a regulated supply? Probably. It’s absolutely worth trying if you are interested. Is it a panacea for reducing noise? Doubtful. Proper layout and amp building practices will be the big determinant of overall noise.
It seems that this latest discussion started with DC offset and then somehow drifted into a discussion of audible noise, which is a totally different thing.
As for noise, what 6L6 said about proper layout and amp building practises definitely are big factors. I have found diyAudio member Bonsai's article to be most informative: hifisonix: How to Wire-up an Audio Amplifier
If they are taken care of, then power supply ripple is next - less ripple, less noise. Its effect though depends on a circuit's power supply rejection ratio (PSRR). Single ended circuits are not so good, complementary push-pull circuits are better. So single ended circuits need lower ripple whereas push-pull circuits can tolerate higher ripple levels.
A regulated supply will reduce ripple and maintain a constant voltage. For an output stage, an exact constant voltage is probably not critical. More power supply capacitance, more power supply filtering (CRC or CLC), or a capacitance multiplier will also reduce ripple.
Of course speaker sensitivity plays a big part in audible noise. A noisy amplifier may seem quiet with a 86dB speaker. This can fool the builder into thinking that proper amp building practises that many espouse are just crap. 🙂
As for noise, what 6L6 said about proper layout and amp building practises definitely are big factors. I have found diyAudio member Bonsai's article to be most informative: hifisonix: How to Wire-up an Audio Amplifier
If they are taken care of, then power supply ripple is next - less ripple, less noise. Its effect though depends on a circuit's power supply rejection ratio (PSRR). Single ended circuits are not so good, complementary push-pull circuits are better. So single ended circuits need lower ripple whereas push-pull circuits can tolerate higher ripple levels.
A regulated supply will reduce ripple and maintain a constant voltage. For an output stage, an exact constant voltage is probably not critical. More power supply capacitance, more power supply filtering (CRC or CLC), or a capacitance multiplier will also reduce ripple.
Of course speaker sensitivity plays a big part in audible noise. A noisy amplifier may seem quiet with a 86dB speaker. This can fool the builder into thinking that proper amp building practises that many espouse are just crap. 🙂
I think my BA3 has more gain (than 15). F5 is supposed to be 15 db. My BA3 has noticably higher gain. I notice Aleph J is similar. My M2 seems more like the F5 in terms of gain, I assume 15ish.
My BA3 front ends have more gain than my BA 2018 line stage, both have more gain than Iron Pre, set at 6dB.
Russellc
My BA3 front ends have more gain than my BA 2018 line stage, both have more gain than Iron Pre, set at 6dB.
Russellc
hello,
can this ba3-pp os connected directly into a tube front end?
or even crazier connect them to tube preamp?
thanks.
can this ba3-pp os connected directly into a tube front end?
or even crazier connect them to tube preamp?
thanks.