Can't be done unless you are talking about a servo. Maybe can be done if you add feedback. DC drifts too much, if you have a power amp with no cap it would be an accident waiting to happen.
http://www.diyaudio.com/forums/swap-meet/294822-jlh-headphone-amp-dc-servo-pcb.html
This might work. But I haven't really done much research into it.
If you obsolutely need to get rid of the cap you could look at the vfet front end (long thread on diyaudio) or some of the other preamps based on the f5. I think the f5 topology with no feedback is probably gonna need a cap no matter what. It's the price you pay for no feedback.
This might work. But I haven't really done much research into it.
If you obsolutely need to get rid of the cap you could look at the vfet front end (long thread on diyaudio) or some of the other preamps based on the f5. I think the f5 topology with no feedback is probably gonna need a cap no matter what. It's the price you pay for no feedback.
what is the purpose of using servo? 🙄
if only to null dc offset, caps can do it better.
but if to eliminate the use of caps, there are still so many caps used in servo it self.
so what is the exact purpose??? 😕
(i have tried many servos, in my opinion none of them can make the sound better than caps, and i also thinking if servo can really works better than caps maybe NP will use them already) 😎
if only to null dc offset, caps can do it better.
but if to eliminate the use of caps, there are still so many caps used in servo it self.
so what is the exact purpose??? 😕
(i have tried many servos, in my opinion none of them can make the sound better than caps, and i also thinking if servo can really works better than caps maybe NP will use them already) 😎
Not really needed, i just like options. For non feedback pre amp, i have Gainwire MK2 from Dadod. It use servo and bjt only.
I think the Vfet front end looks really nice...it's on my list of things to build next.
When Nelson hints at a "hot rod" version of the BA-3 in the BA-3 article he mentions a BA-3 with cascodes, more bias, etc. He is describing the Vfet front end.
I would decribe the BA-3 preamp as "natural" and a little relaxed. Very refined sounding, maybe to a fault depending on your setup.
When Nelson hints at a "hot rod" version of the BA-3 in the BA-3 article he mentions a BA-3 with cascodes, more bias, etc. He is describing the Vfet front end.
I would decribe the BA-3 preamp as "natural" and a little relaxed. Very refined sounding, maybe to a fault depending on your setup.
this is a much better and wiser choice,
go ahead build one, you will never be disappointed
just ignore about those servos build, really.
In my DCG3 preamp development experience I have drawn the opposite conclusion i.e. that DC servo always sounded cleaner than coupling capacitors. Surely cheaper and smaller at least.
Having listened to a friend's BA-3 in mine and in another system I would say that you described it fairly accurately. Not impressive on bass slam or 3D and resolution but light footed and engaging. Leaning to a Jaco Pastorius sound vs a Jah Wobble sound if preamps were musos 😀
I am using my Ba3 pre without output caps but with input transformers at the power amps.
I tried it with output caps and found that they closed in the "space" around the sound and was not to my liking. The sound with the transformers is clear, detailed, more spacious and more dynamic than my previous setup using a passive Slage AVC(which I still think sounds very good). In my opinion this is an excellent pre for classical music which is primarily what I listen to. The tonality and balance of the sound is greatly affected by the choice of the volume attenuator.
Regarding DC offset I dont find much drift (typically+/_2mv) once the pre is fully warmed up which takes around three hours assuming the same ambient temperature on different days.
nash
I tried it with output caps and found that they closed in the "space" around the sound and was not to my liking. The sound with the transformers is clear, detailed, more spacious and more dynamic than my previous setup using a passive Slage AVC(which I still think sounds very good). In my opinion this is an excellent pre for classical music which is primarily what I listen to. The tonality and balance of the sound is greatly affected by the choice of the volume attenuator.
Regarding DC offset I dont find much drift (typically+/_2mv) once the pre is fully warmed up which takes around three hours assuming the same ambient temperature on different days.
nash
I have my experience for BA3 with servo
in my opinion, at first impression servo indeed make the sound very clean and fast, its look like as a surprise because its very different to caps sound.
but, I don't know why the longer I listened to the song the more boring to my ears.
very lack in musicality and warmth, and it become very stiff after several times.
then I switch back to use caps, and my ears happy with it.
in my opinion, at first impression servo indeed make the sound very clean and fast, its look like as a surprise because its very different to caps sound.
but, I don't know why the longer I listened to the song the more boring to my ears.
very lack in musicality and warmth, and it become very stiff after several times.
then I switch back to use caps, and my ears happy with it.
Salas, looks like you have a new preamp design.
If it's anything like your phono stage I will be building it. Boards available?
Not yet. I just finished with the final touches to the board files. Will let you guys know in its thread.
+1
I usually don't waste my time building AC coupled preamps/buffers.
The BA-3 was an exception, since I read a lot of positive reviews before building it.
I'm currently using 1k pots for 1 and 2. Can I swap in irf610 and irf9610 without changing them?
Stock pots are 500R intended for 2SJ/K Mosfets.
You should be fine w/1K. But most people here use the fairchild mosfet.
You should be fine w/1K. But most people here use the fairchild mosfet.
I am currently using the Fairchild Mosfets. I feel the sound it too bright. I tried them in my Aleph 3 and found it to make my system even more bright. That's why I'm considering using the 610/9610 in the BA-3 as well as going back to the 9610 in the Aleph 3.