Hi Salas,
Are you saying that a 330 ohm Kiwame sounds more dynamic than normal resistor of 220 ohm? I started with normal 1000 ohm, then tried 50 ohm Caddock MK132 and then no resistor at all. In all cases the dynamics were correlated with resistor value, i.e. no resistor sounds better than 50 ohm Caddock.
As for the gate resistor, I have found before that higher value resistor tend to loose detail. In another project I replaced a 1k Riken with 120 ohm normal resistor. And guess what, the cheap resistor sounded notably better (more detail and presence).
Of course, any oscillations introduced by modding the circuit could easily offset the benefits.
Is there any easy way to check (measure) if there are any parasitic oscillation present in the circuit? Such as measuring supply current for instance?
Are you saying that a 330 ohm Kiwame sounds more dynamic than normal resistor of 220 ohm? I started with normal 1000 ohm, then tried 50 ohm Caddock MK132 and then no resistor at all. In all cases the dynamics were correlated with resistor value, i.e. no resistor sounds better than 50 ohm Caddock.
As for the gate resistor, I have found before that higher value resistor tend to loose detail. In another project I replaced a 1k Riken with 120 ohm normal resistor. And guess what, the cheap resistor sounded notably better (more detail and presence).
Of course, any oscillations introduced by modding the circuit could easily offset the benefits.
Is there any easy way to check (measure) if there are any parasitic oscillation present in the circuit? Such as measuring supply current for instance?
It may depend on what kind of ''normal'' metal film resistors we used or our interconnects or how easy our load was. But you compared to 20 times lower good quality, and to nothing. So I can't draw conclusions easily. Yes my 330 Kiwame sounded better than 220 off the shelf Chinese something.
For input, your 1k to 120 comparison (in another circuit) is in the order of 10 so the value difference would normally have prevailed.
But as I wrote earlier, if B1 is to stay put in a given system, then its better to practice preference. The lower it tolerates, the better. And better be best quality if any.
Oscillation you will see if happening, on high frequency square waves with a generator and a scope. 10, 20, 50, 100kHz. Little peaks and ringing at the edges.
For input, your 1k to 120 comparison (in another circuit) is in the order of 10 so the value difference would normally have prevailed.
But as I wrote earlier, if B1 is to stay put in a given system, then its better to practice preference. The lower it tolerates, the better. And better be best quality if any.
Oscillation you will see if happening, on high frequency square waves with a generator and a scope. 10, 20, 50, 100kHz. Little peaks and ringing at the edges.
would this work?
I'm not sure if this would be considered off topic. If so, please ignore my question.
I was thinking of the problem with the low psrr of the White jfet topology. It seems that the problem is that the current from the upper jfet is converted into a voltage that is referenced to the positive supply voltage. The lower jfet, which is referenced to the negative supply, is driven with this voltage. Therefore, any noise between these supplies is amplified by the circuit.
A simple solution would be if a current mirror was placed in the drain of the upper fet. The secondary side or the mirror could have a resistor to the negative supply (I am assuming symmetric supplies). This voltage would be thus referenced to the negative supply, and would therefore have far better supply rejection.
If that would work I'm not sure. In any case the circuit would be not-so-simple anymore as it would need two more transistors and some resistances. On the other hand, it could perhaps be possible to loose the capacitive coupling altogether as it might be possible to use the current to directly drive the gate of the lower jfet.
Any thoughts?
-edit: it occurred to me that my idea would introduce a phase inversion and hence positive feedback. Will have to think about it some more.
I'm not sure if this would be considered off topic. If so, please ignore my question.
I was thinking of the problem with the low psrr of the White jfet topology. It seems that the problem is that the current from the upper jfet is converted into a voltage that is referenced to the positive supply voltage. The lower jfet, which is referenced to the negative supply, is driven with this voltage. Therefore, any noise between these supplies is amplified by the circuit.
A simple solution would be if a current mirror was placed in the drain of the upper fet. The secondary side or the mirror could have a resistor to the negative supply (I am assuming symmetric supplies). This voltage would be thus referenced to the negative supply, and would therefore have far better supply rejection.
If that would work I'm not sure. In any case the circuit would be not-so-simple anymore as it would need two more transistors and some resistances. On the other hand, it could perhaps be possible to loose the capacitive coupling altogether as it might be possible to use the current to directly drive the gate of the lower jfet.
Any thoughts?
-edit: it occurred to me that my idea would introduce a phase inversion and hence positive feedback. Will have to think about it some more.
Re: Re: would this work?
Your drawing skills always amaze me...
Zen Mod said:
Your drawing skills always amaze me...
An externally hosted image should be here but it was not working when we last tested it.
Re: Re: Re: Re: Re: would this work?
yup - same as those headphones without cord ( workers in noisy
areas) ...... noise and anti-noise .....
anyway - I'm curious - Vaistiny Konza is - where ?
are you in tuzemstvo or inozemsvo ?
juma said:
Aaahh, you want noisy CCS - to make buffer sound more "analog like" - yesss, what's music without noise, right ?
yup - same as those headphones without cord ( workers in noisy
areas) ...... noise and anti-noise .....
anyway - I'm curious - Vaistiny Konza is - where ?
are you in tuzemstvo or inozemsvo ?
B1
Hi all,
I'm new to the forum and I'm not sure if this is the best thread to ask this question.
I've been using a Goldpoint SA4 level control between an Aragon D2A2 and an Aragon 8008BB. I've been wondering If I'd be better off with bit of gain instead. If so, would the B1 be the way to go? What would be the advantages over passive?
Thanks...
Hi all,
I'm new to the forum and I'm not sure if this is the best thread to ask this question.
I've been using a Goldpoint SA4 level control between an Aragon D2A2 and an Aragon 8008BB. I've been wondering If I'd be better off with bit of gain instead. If so, would the B1 be the way to go? What would be the advantages over passive?
Thanks...
Re: B1
B1 is a buffer stage, no gain in signal. If you think but not sure if you need gain, take a single pot, add some coax with terminals at both ends and try with passive volume only between your source (CD for example) and power amp. If you get enough output from source to fully drive the power amp, B1 should do. If you can go with the single pot all the way and feel that the amp lacks output power, then, some gain in the control/preamp unit would help. In that case, you might consider NS10 with a proper, modern shunt PSU... like some of us did
http://www.diyaudio.com/forums/showthread.php?s=&threadid=76557&perpage=25&pagenumber=1
and NS10 with Shiny PS
sparky6 said:
B1 is a buffer stage, no gain in signal. If you think but not sure if you need gain, take a single pot, add some coax with terminals at both ends and try with passive volume only between your source (CD for example) and power amp. If you get enough output from source to fully drive the power amp, B1 should do. If you can go with the single pot all the way and feel that the amp lacks output power, then, some gain in the control/preamp unit would help. In that case, you might consider NS10 with a proper, modern shunt PSU... like some of us did
http://www.diyaudio.com/forums/showthread.php?s=&threadid=76557&perpage=25&pagenumber=1
and NS10 with Shiny PS
OK guys,here I am fat dumb and happy thinking I'm gonna build me a B1 to put into the system to replace the present POS preamp I have.
Now the hornets nest gets stirred a little and I hear (read) about Pumpkins and NS10's and ShinyPS's of which I know nothing about. I have no Pumpkin boards on order nor Shinnies nor do I know if I'll be able to obtain one should I need one. I feel like I got off the elevator on the fifth floor. I get the feeling I will need a "preamp" when all is said and done. Would that be a "pumpkin"?
Ray
Information is not knowledge
Knowledge is not wisdom
Wisdom is not truth
Truth is not beauty
Beauty is not love
Love is not music
Music is the best !
Frank Zappa.
Re: Re: Re: Re: Re: Re: would this work?
Ma jok, to je lokalna fora - Munze Konza (Zemun Zakon) ! Vaistinu Konza (Zakon) ! (tako se pozdravljaju i odpozdravljaju zemunci na satrovackom)
A dal'je tuzemstvo ili inozemstvo - ostaje da se vidi !
Anyway, I don't think that noise scheme will work here - it's quite different from Broskie's implementation in Aikido preamp. Furthermore, B1 doesn't need it - it has a very good intrinsic PSRR already. I know what would make you happy - nice, hot, glowing 6SN7 as WCF
Zen Mod said:
anyway - I'm curious - Vaistiny Konza is - where ?
are you in tuzemstvo or inozemsvo ?
Ma jok, to je lokalna fora - Munze Konza (Zemun Zakon) ! Vaistinu Konza (Zakon) ! (tako se pozdravljaju i odpozdravljaju zemunci na satrovackom)
A dal'je tuzemstvo ili inozemstvo - ostaje da se vidi !
Anyway, I don't think that noise scheme will work here - it's quite different from Broskie's implementation in Aikido preamp. Furthermore, B1 doesn't need it - it has a very good intrinsic PSRR already. I know what would make you happy - nice, hot, glowing 6SN7 as WCF
brutepuppy said:
here I am fat dumb and happy thinking I'm gonna build me a B1 to put into the system to replace the present POS preamp I have.
Now the hornets nest gets stirred a little and I hear (read) about Pumpkins and NS10's and ShinyPS's of which I know nothing about. I have no Pumpkin boards on order nor Shinnies nor do I know if I'll be able to obtain one should I need one. I feel like I got off the elevator on the fifth floor. I get the feeling I will need a "preamp" when all is said and done. Would that be a "pumpkin"?
Ray
Information is not knowledge
Knowledge is not wisdom
Wisdom is not truth
Truth is not beauty
Beauty is not love
Love is not music
Music is the best !
Frank Zappa.
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