Thank you
Hi Hendrik & everyone,
I was inspired to try the active ccs gain on my Hendrik X Bosoz this morning.
I recall going back to the resister current source last time after attempting the simple 610/zener circuit.
So I look at a few options in Alain Dupont's design of a 317 negative regulator for 10-15 volt negative supply with a 20uf capacitor across the zenor.
Compared to the resister current sournce the tonal balance was altered a little, more pronounced mids, somehow less very fine detail..less ambience ...a flatter sound.
I then read another post on using a LM329 precision voltage reference and I just happened to have a pair from a super reg project I have not started.
Adusting the 317 to 15 volts, I inserted the LM 329, took out the capacitor and used 1k for about 8 ma through the Lm329 with a source resistance of 34 ohms (68/68R).
My measurements confirmed there is exactly 2.7 V across the source resister to the 15 volt..79 ma.
Well, the sound is wonderful and I cannot hear it apart from the resister ccs. I have no scientific answers other than the LM329 is from the specs, much quieter and more stable with tempco.
My feeling is that the LM329 allows a minimalist approach..less is more.
I might try cascoding the output of the BOSOZ now.....
macka
I was inspired to try the active ccs gain on my Hendrik X Bosoz this morning.
I recall going back to the resister current source last time after attempting the simple 610/zener circuit.
So I look at a few options in Alain Dupont's design of a 317 negative regulator for 10-15 volt negative supply with a 20uf capacitor across the zenor.
Compared to the resister current sournce the tonal balance was altered a little, more pronounced mids, somehow less very fine detail..less ambience ...a flatter sound.
I then read another post on using a LM329 precision voltage reference and I just happened to have a pair from a super reg project I have not started.
Adusting the 317 to 15 volts, I inserted the LM 329, took out the capacitor and used 1k for about 8 ma through the Lm329 with a source resistance of 34 ohms (68/68R).
My measurements confirmed there is exactly 2.7 V across the source resister to the 15 volt..79 ma.
Well, the sound is wonderful and I cannot hear it apart from the resister ccs. I have no scientific answers other than the LM329 is from the specs, much quieter and more stable with tempco.
My feeling is that the LM329 allows a minimalist approach..less is more.
I might try cascoding the output of the BOSOZ now.....
macka
Hi Macka,
so if I understand your report correctly I don´t have to bother testing a current source in my X-BOSOZ since it sounds the same as the resistor version?
I will have a look at the X-BOSOZ in my DAC though cause I believe I´ve used a simple 9V1 zener in here (and no cap paralell)
thanks,
William
so if I understand your report correctly I don´t have to bother testing a current source in my X-BOSOZ since it sounds the same as the resistor version?
I will have a look at the X-BOSOZ in my DAC though cause I believe I´ve used a simple 9V1 zener in here (and no cap paralell)
thanks,
William
Hi William,
This needs to be verifiied by the Master but as I recall it depends on if you are using the pre amp as an unbalanced to balanced converter. In the is mode the outputs as such are more likely to be equal where an active current source is used.. Previously an active current source altered the sonic signature.
I think in this mode the ccs improves back ground noise and has lower distortion, but best of all the gains in CMRR are not at the loss of sonic qualities.
macka
This needs to be verifiied by the Master but as I recall it depends on if you are using the pre amp as an unbalanced to balanced converter. In the is mode the outputs as such are more likely to be equal where an active current source is used.. Previously an active current source altered the sonic signature.
I think in this mode the ccs improves back ground noise and has lower distortion, but best of all the gains in CMRR are not at the loss of sonic qualities.
macka
Hi,
I´m using it all balanced. Feeding the X-BOSOZ with ONO and the x-bosoz output stage of my dac (fed by the balanced output of the Crystal chip).
At the moment the x-bosoz in my dac doesn´t even have a regulated supply but easily outperforms the OPA627´s in the regular output stage. I think this will be the next project after finishing the restauration of my Aleph5 and getting rid of the humming transformers in my Aleph-X´s................
William
I´m using it all balanced. Feeding the X-BOSOZ with ONO and the x-bosoz output stage of my dac (fed by the balanced output of the Crystal chip).
At the moment the x-bosoz in my dac doesn´t even have a regulated supply but easily outperforms the OPA627´s in the regular output stage. I think this will be the next project after finishing the restauration of my Aleph5 and getting rid of the humming transformers in my Aleph-X´s................
William
Hi William,
We are going off-topic, but talking about DAC's:
I also have a X-BOSOZ in my DAC (Kristian/Hendrik). Mine is an AKM DAC which has a balanced voltage output, based on a M-Audio Superdac.
What I am interested in is how you set-up te filtering for your DAC with a Crystal DAC.
I myself upsampled first to 96K, and used a 1-pole filter 3DB at 18Khz plus voltage divider between the DAC and the X-BOSOZ. (three resistors and a capacitor per signal side). According to the specs at 96K input, the AKM needs a brickwall filter at 56Khz.
Greetings, Harry.
We are going off-topic, but talking about DAC's:
I also have a X-BOSOZ in my DAC (Kristian/Hendrik). Mine is an AKM DAC which has a balanced voltage output, based on a M-Audio Superdac.
What I am interested in is how you set-up te filtering for your DAC with a Crystal DAC.
I myself upsampled first to 96K, and used a 1-pole filter 3DB at 18Khz plus voltage divider between the DAC and the X-BOSOZ. (three resistors and a capacitor per signal side). According to the specs at 96K input, the AKM needs a brickwall filter at 56Khz.
Greetings, Harry.
Hi Harry,
I do use an output filter but with a very high -3dB point. It is based on the original filter used in the P3-A and goes something like this:
1k then 2n2//1k to ground, then 510R and 1n5 to ground, input impedance of the output stage is 27k. This is used for each phase. I remember simulating it but not the exact value. Could be near 47kHz.
William
I do use an output filter but with a very high -3dB point. It is based on the original filter used in the P3-A and goes something like this:
1k then 2n2//1k to ground, then 510R and 1n5 to ground, input impedance of the output stage is 27k. This is used for each phase. I remember simulating it but not the exact value. Could be near 47kHz.
William
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