I'm not sure if I get how config B works. If the wiper pot is near 0R, we certainly need a beefy driver stage, no?
Rüdiger
It depends on the resistors before the pot. I use 5kOhm in my system without problem. The 0R potion is rare anyway. The system has to be optimized so that most of the listening happen in the middle position of the pot and when we use a 20kOhm for example the input resistance will be higher then the 5kOhm series resistors anyway most of the time. In my system, at the volume i listen most i have around 10kOhm input resistance.
Ricardo, Frans can answer that. As far as i can see a lot of TO220 BJTs and Enhancement MosFets will work here. Japanese Transistors can have other Pin Out though.
Sampler, there are other ways to setup a J-Fet based balanced input stage. Here are two of them. You can also modify the second schematic ( Claudio ) for non feedback by simply connecting the sources to ground. I think that your solution is optimum though from the standpoint of distortion because it is balanced AND differential.
Attachments
Sorry Joachim, it was too late to edit that nonsense, it's in parallel. This balanced stuff starts to confuse hell out of me. Ok, this is one version of bjt masterpiece. Lot's of gain, 0.5mV form your titan would give about 1Vrms out. Numbers look extremely good. I adopted MiiB's auto biasing, but servoing this thing is not so straight forward as we have common emitters between branches, so correcting offset on one side gives some effect on the other, but 2 servos should manage this. Still working on fet version. Can't figure out what would be the best way to servo it. Can't touch fet sources with low impedance as it spoils cmrr quite badly, so looking for other alternatives.
That is a masterpiece when i just look at it, awesome !!!
I just talked to MiiB. He is in Boston. He comes back on wednesday and may find a servo solution.
I just talked to MiiB. He is in Boston. He comes back on wednesday and may find a servo solution.
And I believe it works so well for couple reasons. Low gain off stage resulting in low feed through, and what gets to sources acts only as feedback. AD711 and good integrating cap doesn't spoil things. But I mentioned that we cant touch fet sources as whole common mode rejection happens there. Even 1M to anywhere starts to spoil it. I will sleep on it. If nothing comes out, it will be your call after all. We can put your strange servo to mirrors.
Attachments
Hi...
I my view the most shielded way is to adopt the use of two independent servo's one for each branch of the amp, I don't fancy the curl way as the servo is in the signal path injected where you'd normally inject current feedback. Hell This here is two complete riaa's with the signal suspended somewhere in the middle of it all....NICE.
Personally I like the balanced input, but I don't particularly like the rest of the chain being balanced
I my view the most shielded way is to adopt the use of two independent servo's one for each branch of the amp, I don't fancy the curl way as the servo is in the signal path injected where you'd normally inject current feedback. Hell This here is two complete riaa's with the signal suspended somewhere in the middle of it all....NICE.
Personally I like the balanced input, but I don't particularly like the rest of the chain being balanced
The total balanced can make sense when it goes right through to the speakers.
The big Adyton Power Amp of the 90th was that way.
On the other had it is easy to get an unbalanced out with a Thats 1200. I find it sonically transparent.
The big Adyton Power Amp of the 90th was that way.
On the other had it is easy to get an unbalanced out with a Thats 1200. I find it sonically transparent.
Oh really... and you can buy that..???
I know the Adyton, and the big ones need a balanced signal as it is two of the smaller models run in opposite phase...a very nice amp, we used it in Munich last year...
The walker turntable I just heard is heavily based on the Forsell...though the arm is very very different...and a new high-pressure design....bitch with the system of compressors he had running in the other room..
I know the Adyton, and the big ones need a balanced signal as it is two of the smaller models run in opposite phase...a very nice amp, we used it in Munich last year...
The walker turntable I just heard is heavily based on the Forsell...though the arm is very very different...and a new high-pressure design....bitch with the system of compressors he had running in the other room..
As far as i know Forsell build 100 and they are somewhere. Not all of them have being sold. Balanced to the speakers has a lot of advantages but this is a long story.
