After building an F5 (found it a tick on the bright and shiny side) and then an F6 (mosfet version - I felt it lacked on dynamics and the bass accuracy of the F5) I am back listening happily to a slightly modified F5 with less feedback an no current limiter ;-)
Here's the thing - I would like to try something I haven't found here yet...
What do you guys think of an output stage ala F4 (or BA-2 for that matter) that's biased like the M2 (optocoupler) and uses a BA-3 voltage stage?
No overall feedback.
After reading quite a few posts it seems the F4 would give me the sound I am looking for. And I don't really want to get the sound of the transformer (F6).
Also I liked the idea of the self adjusting bias...apart from the BA-3 first stage of course which still needs bias an dc adjustment.
My speakers are 2-way passive with impedance below 4 ohms at certain frequencies and 89 dB SPL at 1W/1m.
Thanks for your comments
theRog
Here's the thing - I would like to try something I haven't found here yet...
What do you guys think of an output stage ala F4 (or BA-2 for that matter) that's biased like the M2 (optocoupler) and uses a BA-3 voltage stage?
No overall feedback.
After reading quite a few posts it seems the F4 would give me the sound I am looking for. And I don't really want to get the sound of the transformer (F6).
Also I liked the idea of the self adjusting bias...apart from the BA-3 first stage of course which still needs bias an dc adjustment.
My speakers are 2-way passive with impedance below 4 ohms at certain frequencies and 89 dB SPL at 1W/1m.
Thanks for your comments
theRog
that bush being beaten to death , even if maybe not so visible
though , you can call it (explain) differently , without involving F4 :
M2 OS with multiple outputs , driven with BA3 FE
easy as puzzles , just take care of having properly matched all N's and all P's in OS, sampling current for optobias just from one source resistor pairs
slightly higher rails for FE are good , but not necessary
though , you can call it (explain) differently , without involving F4 :
M2 OS with multiple outputs , driven with BA3 FE
easy as puzzles , just take care of having properly matched all N's and all P's in OS, sampling current for optobias just from one source resistor pairs
slightly higher rails for FE are good , but not necessary
great to hear from one of the main guys!
thanks for your reply.
what would you choose trying to get a slightly rounder F5 sound with the power to drive low impedances?
Thanks for your time and advice.
theRog
thanks for your reply.
what would you choose trying to get a slightly rounder F5 sound with the power to drive low impedances?
Thanks for your time and advice.
theRog
Why not just build the ba-3 amplifier with only a pair of outputs? Pretty much the same thing. Iam not sure the bias method (octocoupler) is really an advantage. And not being able to adjust the bias is no fun.
If you like the f5 try it with multiple pairs of outputs and more bias. Might be the answer.
If you like the f5 try it with multiple pairs of outputs and more bias. Might be the answer.
Having built both F5 and F6, I understand your feelings. I found them similar in signature, or at least same family sound wise. Like you said, a little to bright and shiny.I would never guess from the sound of F6 that there was a transformer in the signal path.
Dont misunderstand, the F5 impressed me so much when I built it, that I began my exodus from vacuum tubes. Based on what you say, I think a Complementary BA3 would please you fine, It did me. A bit more of a mature design from the F5, giving up very little, and in fact gaining quite a bit to my tastes anyway.
If you must have optocoupler devices, build M2. Its a wonderful amplifier. You might also consider Zenmod's M25 amp, or his Sissysit version, which I am building now. M 25 might be better with your 4 ohm speakers, but BA3 would drive them very well too.
I converted my F6 to Aleph J, a very, very enjoyable amplifier which surprised me greatly. My speakers like it fine.
So, From my view, (which it isnt) Seems as though M25 might be the ticket for you? Optocouplers, Hall chips, unconstipated, how can you go wrong?
Russellc
Dont misunderstand, the F5 impressed me so much when I built it, that I began my exodus from vacuum tubes. Based on what you say, I think a Complementary BA3 would please you fine, It did me. A bit more of a mature design from the F5, giving up very little, and in fact gaining quite a bit to my tastes anyway.
If you must have optocoupler devices, build M2. Its a wonderful amplifier. You might also consider Zenmod's M25 amp, or his Sissysit version, which I am building now. M 25 might be better with your 4 ohm speakers, but BA3 would drive them very well too.
I converted my F6 to Aleph J, a very, very enjoyable amplifier which surprised me greatly. My speakers like it fine.
So, From my view, (which it isnt) Seems as though M25 might be the ticket for you? Optocouplers, Hall chips, unconstipated, how can you go wrong?
Russellc
A wide variety of speakers, least efficient are 85 dB 7 inch woofer pair in my bedroom system where the M2 generally is used. In same system, Also another pair MTM D'appolitp of about 91 dB. In other rooms, Econowaves using 15 inch JBL 2235H and B&C compression driver, in 5 cu ft, aprox. mid 90's or so. I also use it in living room sometimes with Tekton Enzo towers, 98 dB advertised, seems a tad less to me but very efficient, Occasionally Altec A7 pair in basement of 100 dB.
Usually in bedroom with already mentioned mid 80's 1/2 cu ft stand mounted speakers. It is with my vinyl system with a BA3 front end and Pearl 2 phono pre, so plenty of gain for that room. Right now, in TV room playing through Econowaves.
Russellc
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one question : did you explore all what can be explored - for F5 using last iteration schematic , with third pot introduced at input JFets sources?
with that thingy , you can tweak sound in pretty broad area, counting that you have some relatively simple program and at least semi-decent sound card
Mine was from Peter Daniels boards, so did not have the third pot. May have to get newer boards and try it.
Russellc
Russellc
ZenMod: To be honest I haven't played with P3 as much I probably should have to see what it does sound-wise... I am going to do so now, thanks!
Russellc: Thank you very much for your hints towards M2, BA-3 complementary and others. I might try the M2 first to find out whether it was the transformer in the F6 I heard after all. If so, then I would be able to use a BA-3 FE instead of the transformer and might try adding more OS to see what that does to the sound...
I'll probably find years after this that the Aleph J would have been what I was looking (listening) for ;-)
Cheerio
theRog
Russellc: Thank you very much for your hints towards M2, BA-3 complementary and others. I might try the M2 first to find out whether it was the transformer in the F6 I heard after all. If so, then I would be able to use a BA-3 FE instead of the transformer and might try adding more OS to see what that does to the sound...
I'll probably find years after this that the Aleph J would have been what I was looking (listening) for ;-)
Cheerio
theRog
What you will probably find is that you will build all or most of them! They are very like Lay's potato chips. LOL
Russellc
Hot glue one in
Well, that is normally a good idea, will take special care. The boards are tiny, smaller than a business card!
Russellc
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