I have never use that part. Don't you think that going all discrete would be more "elegant"?
Let me create the differential input stage with the N-FET and post it on Masterpiece.
(I am not clear if you want to use that topology here or not)
No, i did not listen to the La Boheme.
I have parts of it, for example the output transformers.
I have tried them in my system and the result was a very homogenous, musical and beautiful sound. It lacks a bit a tiny amount of air in the top and transient snap was a bit dull. This transformer can of cause be connected in a plethora of ways and i did not try all that is possible.
The OPA1632 is one of the best stages i heard, discrete or not.
It is extremely dynamic without any hint of Opamp sound. I mean with "Opamp sound " a sound that can be very good in the bass but lacks resolution in the treble, like it would change character from low to high. Not this one but i use it only in shunt feedback.
I find it very elegant the way i use it.
You may come up with something better.
Yes, we can shift the discussion about a "Super Phono " to the Masterpiece thread.
I can imagine that the La Boheme input stage is the best solution for the Interfets.
They have such low noise that one pair is sufficient, even in a balanced differential stage.
I have parts of it, for example the output transformers.
I have tried them in my system and the result was a very homogenous, musical and beautiful sound. It lacks a bit a tiny amount of air in the top and transient snap was a bit dull. This transformer can of cause be connected in a plethora of ways and i did not try all that is possible.
The OPA1632 is one of the best stages i heard, discrete or not.
It is extremely dynamic without any hint of Opamp sound. I mean with "Opamp sound " a sound that can be very good in the bass but lacks resolution in the treble, like it would change character from low to high. Not this one but i use it only in shunt feedback.
I find it very elegant the way i use it.
You may come up with something better.
Yes, we can shift the discussion about a "Super Phono " to the Masterpiece thread.
I can imagine that the La Boheme input stage is the best solution for the Interfets.
They have such low noise that one pair is sufficient, even in a balanced differential stage.
Very, very unlikely....that I would be tempted to say impossible!!
But thanks anyway for the consideration 🙂
OK, trust me, let us use the OPA1632. I have over 2 years of experience with it in several stages i build. Nobody, professionals or amateurs, did ever comment that is has an opamp sound. But as i said, i use it only in shunt feedback.
Sounds good, it will be a learning experience for me since I have never considered so far a phono stage with an op-amp in it.
My qyestion is, what topology would you like to persue on the MasterPiece?
Single Jfet with Unterfet like Bohemia style?
Or you have something better in mind?
The La Boheme is a bit what Allen Wright did with his Real Time Preamp.
It has the advantage that the RIAA components are only ones there so cancelation will not happen
and common mode problems are solved, BUT
14dB @ 20kHz dynamic range disadvantage and more noise and distortion then shunt feedback. You see, i am not a fan of passive.
Stefanoo, yes, the La Boheme input stage with your Interfets and the OPA1632 in shunt feedback. This is technical sound plus a very short signal path.
I will draw it up for you. When issue is the bipolar cascades. We have alraedy takes about the huge current that the Interfet can consume. So we can not use small signal BJts like the BCs that the La Boheme uses. That is really not a problem. Zetex makes excellent medium power SMD BJts or we could use the TO220 Sanyos.
It has the advantage that the RIAA components are only ones there so cancelation will not happen
and common mode problems are solved, BUT
14dB @ 20kHz dynamic range disadvantage and more noise and distortion then shunt feedback. You see, i am not a fan of passive.
Stefanoo, yes, the La Boheme input stage with your Interfets and the OPA1632 in shunt feedback. This is technical sound plus a very short signal path.
I will draw it up for you. When issue is the bipolar cascades. We have alraedy takes about the huge current that the Interfet can consume. So we can not use small signal BJts like the BCs that the La Boheme uses. That is really not a problem. Zetex makes excellent medium power SMD BJts or we could use the TO220 Sanyos.
Well, one problem remains. When we do the La Boheme style input we have to use AC coupling to the next stage.
Cant we fold it over like i roenders folded cassode amplifier..something like a dual differential where we use the second to assemble the signal..??
Something a bit like this.. Goldmund style..
http://www.diyaudio.com/forums/solid-state/97144-symasym-roender-style.html#post1145588
http://www.diyaudio.com/forums/solid-state/97144-symasym-roender-style.html#post1145588
I was thinking, can't we folded cascade the output of the Boheme?
I personal don't disagree with low value coupling cap it could have some advantages over DC servo if helps keeping things simpler.
Both "legs" of the La Boheme run on the same voltage , that is the problem.
Also it a cured to me that with shunt feedback we need a rather low value input resistor or we run into a noise problem. That low value resistor needs a high value cap.
Say we use a 1kOhm resistor and then you see the problem.
The cap can be avoided, like i do in the Rauschfrei but that needs P-Channel J-Fets too.
I simply do not have a simple solution here. We can go the passive road but somehow it makes my stomach hurt.
Allens Real Time Preamp is that way, tube-hybrid. I had it in my system and as liquid, airy and beautiful it sounded for me it lacked grunt and killer instinct.
Also it a cured to me that with shunt feedback we need a rather low value input resistor or we run into a noise problem. That low value resistor needs a high value cap.
Say we use a 1kOhm resistor and then you see the problem.
The cap can be avoided, like i do in the Rauschfrei but that needs P-Channel J-Fets too.
I simply do not have a simple solution here. We can go the passive road but somehow it makes my stomach hurt.
Allens Real Time Preamp is that way, tube-hybrid. I had it in my system and as liquid, airy and beautiful it sounded for me it lacked grunt and killer instinct.
When you study the RTP 3C it is very similar to the La Boheme but with tubes :
Schematics
Later versions, the one i heard, had bipolars instead of fets at the input.
Somewhere here on this tread Allen published that circuit.
It is very similar to the Fet version though.
Schematics
Later versions, the one i heard, had bipolars instead of fets at the input.
Somewhere here on this tread Allen published that circuit.
It is very similar to the Fet version though.