B1 input impedance seems to be ~200Kohm and output impedance ~220ohm.
See : http://www.diyaudio.com/forums/atta...-gb-dc-coupled-b1-buffer-shunt-psus-salb1.gif
I'm thinking about using E88CC as White's cathode follower, anybody used something similar? High current, popular tube, application is known as one of the best.
I am wonder if this one would fit for soekris:
NovaPlus - Balanced Preamp
It is designed by a guy who previously worked for Lampizator as PCB/tube modules designer.
NovaPlus - Balanced Preamp
It is designed by a guy who previously worked for Lampizator as PCB/tube modules designer.
A capacitor, thus also this one, has 2 duties: above the passband it shall impose an increasing "short" in order to provide a filter function. In the passband it shall be invisible to the signal i.e. should ideally be a perfect resistive infinite resistance - is it?
It's life in the passband is the one of abuse - here, electrical energy constantly trying to reach earth trough it, wildly varying in both frequency and level. An often very foul ground. But it must stand there unaffected and ideal in order not to affect the signal.
I think it is a faulty model to think that a capacitor can be "way out of the audio band" - it for sure work with the whole spectra. Its just that it has to do two different jobs depending on the content of the signal and its a gradual effect where it start to effect the passband well before our usual -3dB reference point for f0.
So here, in order to be sonically transparent it have to do the stunt of doing absolutely nothing - this is not neccesarily easy.
Capacitors are, in general, The evil.
//
It's life in the passband is the one of abuse - here, electrical energy constantly trying to reach earth trough it, wildly varying in both frequency and level. An often very foul ground. But it must stand there unaffected and ideal in order not to affect the signal.
I think it is a faulty model to think that a capacitor can be "way out of the audio band" - it for sure work with the whole spectra. Its just that it has to do two different jobs depending on the content of the signal and its a gradual effect where it start to effect the passband well before our usual -3dB reference point for f0.
So here, in order to be sonically transparent it have to do the stunt of doing absolutely nothing - this is not neccesarily easy.
Capacitors are, in general, The evil.
//
Anyone actually do a valve output stage? Anyone know of any build logs of a dual mono build? I have two boards, a bunch of power supplies built, I just need to figure out an output stage, and get trannies.
Has anyone seen a differential output?
There doesn't seem to be a lot new info outside the few threads in here, and still not a lot outside of troubleshooting questions
Has anyone seen a differential output?
There doesn't seem to be a lot new info outside the few threads in here, and still not a lot outside of troubleshooting questions
I used Bruno Putney balanced preamp, see the Group buy section.
2 dams in balanced setup.
Added a volcb volume instead of the pot.
Sounds like a preamp should.
Will test it against a discrete preamp later on...
2 dams in balanced setup.
Added a volcb volume instead of the pot.
Sounds like a preamp should.
Will test it against a discrete preamp later on...
I use the raw output from both boards, however as the BPBP has two inputs I sometimes configure the boards as 'normal' instead of balanced and use the op-amp XLR dam output to compare two dams; i.e different filters or vref cap mod. (easy with DAM1021 rev3) or different versions flac/dsd of one song. I like that flexibility.
For the moment I only use my 600 ohm headphones direct on the BPBP output, I am building a balanced amp this fall.
For the moment I only use my 600 ohm headphones direct on the BPBP output, I am building a balanced amp this fall.
Unfortunately I don't see any specs regarding gain in his writeup. I see there's a buffer stage, then the diff amp stage with variable gain, do you happen to know the gain spec? Sorry for all the questions, but I appreciate the answers.
I'd like to have both SE and balanced outs. But being indecisive, and not too knowledgable is hindering my process.
I'd like to have both SE and balanced outs. But being indecisive, and not too knowledgable is hindering my process.
The gain is from unity to infinite, that's is the fallback of the BPBP design, i.e. if you break the pot connections the gain raises to max, and may blow your speakers.
I use a ladder BPBP add-on by Hans Polak which limits the gain to 1 or 2 or whatever you like by selecting a resistor value. The bare small I2C SMD PCB is supplied by TviCol, who does the Maya preamps. See group-buy and digital line forums. Hans also designed a input selector switch PCB as another BPBP add-on. I use ladder/switch PCB's and not the Maya controleer, I write my own Arduino code.
I don't mix SE and balanced in one case, I have a separate SE DAC.
I use a ladder BPBP add-on by Hans Polak which limits the gain to 1 or 2 or whatever you like by selecting a resistor value. The bare small I2C SMD PCB is supplied by TviCol, who does the Maya preamps. See group-buy and digital line forums. Hans also designed a input selector switch PCB as another BPBP add-on. I use ladder/switch PCB's and not the Maya controleer, I write my own Arduino code.
I don't mix SE and balanced in one case, I have a separate SE DAC.
I will look into them,thanks! Considering the amount of research I still have left for this stage, I'm going to use the buffered outs until I make up my mind. I'm doing more reading and less building.
Hi,
I just finished my Soerkis Dac and SDTrans384. I just got it wired just to test, however, I tested all voltages and it seems ok, the Dac locks on to the signal, but there is absolutely no sound, I could not figure it out, can someone help me please? I got the power, the I2s signal from my SDTrans, got the volume all the way up, hooked up the raw signal to my amp, and nothing??...HELP!!
Alex
I just finished my Soerkis Dac and SDTrans384. I just got it wired just to test, however, I tested all voltages and it seems ok, the Dac locks on to the signal, but there is absolutely no sound, I could not figure it out, can someone help me please? I got the power, the I2s signal from my SDTrans, got the volume all the way up, hooked up the raw signal to my amp, and nothing??...HELP!!
Alex
This is probably the wrong thread, because it has nothing to do with an output stage. Can you test the SDtrans and the soekris independently? With another I2S DAC and another I2S source?
Thanks for the reply. I was able to figure it out, I just panicked, but thanks anyway.
Any advantage to using this buffer for an output stage for the Soekris?
See schematic in first post.
http://www.diyaudio.com/forums/pass-labs/301812-b1-rev-2-a.html
See schematic in first post.
http://www.diyaudio.com/forums/pass-labs/301812-b1-rev-2-a.html
I have tried Salas DCB1, but it did not bring any improvement in my case. I do however have Vrefs powered with external regs, maybe that is why.
Based on my experience the best output stage for Soekris is no output stage at all since it does not required one. The best combo I got so far is connecting raw outputs (skipping onboard opamps) directly to Modulus 86 amplifier.
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