And here's at 10K. The -3db response occures at 70kHz. This might be caused by high input impedance which is 78K in my case. Feedback resistor is 220k. Compensation caps in feedback loop are required, otherwise square wave shows ringing (if it's correct expression
). I'm using 10p silver mica. Sinewave looks OK with or without caps.
). I'm using 10p silver mica. Sinewave looks OK with or without caps.Attachments
Peter,
Nice looking amp! I could never achive that kind of craftmanship. And now you are showing us the running Aleph X, excellent effort, we are expecting your impresions on sound with the two channels hooked to your speakers.
BTW, you may like to try a slightly smaller cap at the feedback to get an almost perfect sq wave at 1KHz, say 6 or 8 pf, I know you haven't even started to tweek this baby, but just an idea.
Nice looking amp! I could never achive that kind of craftmanship. And now you are showing us the running Aleph X, excellent effort, we are expecting your impresions on sound with the two channels hooked to your speakers.
BTW, you may like to try a slightly smaller cap at the feedback to get an almost perfect sq wave at 1KHz, say 6 or 8 pf, I know you haven't even started to tweek this baby, but just an idea.
apassgear said:
You are right, I put 2 x 10p in series and it looks almost perfect. Also with a cap the high frequency noise is gone. But I didn't had that noise with Aleph 5 which is still caps free.
One other thing. I tried to turn on the amp without input and caps and strange oscilating noise came up.
Now with the input connected and caps in place no thump at all while turning the amp on.
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Glad that the caps at feedback worked OK.
On noise and startup oscillations I would try to replace the Thermistors at the Pi filter in your PSU, even though I have never tested thermistors in that position my impresion is that they are not very stable as resistors and they mey wonder in resistance at certain intermidiate temps. IMO a good wire wound of say 0.8 or 1 Ohm of 20 or more W (or combination of) is the most desirable resistor in that position. And you will still retain the inrush current control you are seeking.
On noise and startup oscillations I would try to replace the Thermistors at the Pi filter in your PSU, even though I have never tested thermistors in that position my impresion is that they are not very stable as resistors and they mey wonder in resistance at certain intermidiate temps. IMO a good wire wound of say 0.8 or 1 Ohm of 20 or more W (or combination of) is the most desirable resistor in that position. And you will still retain the inrush current control you are seeking.
Here's my tonight's setup. It's only temporary, till I install proper drivers in this dividing wall. The other room, which is my workshop, will make the drivers enclosure.
So here's what I'm listening on to the amps. First thing that comes to mind is how effortlessly the amps present the music. They seem not to have the character of their own. The highs are smooth and silky, the midrange very natural and detailed, bass full of authority and well defind (and I'm not full of BS, BTW). I think those amps bring the listener closer to the music that my other Alephs. As I said, it's almost like a curtain is removed. Still the real comparison would be done when I placed them in my main system which I am more familiar with.
Scopemeter I have for last 8 years, the new one was CAD 3000, but I didn't pay that much.
It's only temporary, till I install proper drivers in this dividing wall. The other room, which is my workshop, will make the drivers enclosure. So here's what I'm listening on to the amps. First thing that comes to mind is how effortlessly the amps present the music. They seem not to have the character of their own. The highs are smooth and silky, the midrange very natural and detailed, bass full of authority and well defind (and I'm not full of BS, BTW
). I think those amps bring the listener closer to the music that my other Alephs. As I said, it's almost like a curtain is removed. Still the real comparison would be done when I placed them in my main system which I am more familiar with.Scopemeter I have for last 8 years, the new one was CAD 3000, but I didn't pay that much.
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Yeah, I did the speakers. Obvious influence of B&W 802 and that's how they look the best: in Black & White. I'm using original B&W tweeter, Accuton ceramic midrange and Cabbase 8" woofer in transmission line design. Crossover is in separate enclosure and the mid cabinet is filled with sand. Pretty good sounding speakers.
I'm using original B&W tweeter, Accuton ceramic midrange and Cabbase 8" woofer in transmission line design. Crossover is in separate enclosure and the mid cabinet is filled with sand. Pretty good sounding speakers.
Peter Daniel said:Well, some of my first impressions listenng to one channel of the X amp, comparing to Aleph 5. The new amp seems to be more relaxed with much better sounding vocal. Although it's only one channel I think I can perceive much more deph. The highs are more silky and bass is less flabby, seems like more control there (overall, it's almost like a curtain was removed
The comments remind me of people's initial impressions of the balanced Zen linestage versus the original BOZ.
I wonder if there is a connection here. (Something to do with the balanced nature of the circuits?)
eL
More to the point of thermistors as an R in an CRC Pi filter.
At power-up the thermistor will get hot and the resistance will drop quite steeply but as soon as the caps are filled the temp will start to lower to the regular duty and so the resistance will start to creep up, I guess in not a very ordely way and may be with a lot of noise. Moreover, I think that thermistors will differ quite a lot from sample to sample from its temp/resistance caracteristics so you may find that your + and - rail behave differently. I guess this is the last thing one may want to have on an AX.
I dont know who, but someone posted a link to KC00X thermistors spec sheet in this or other thread, you may want to check the tolerances for this devices.
Also, NP indicated that on some of Pass Labs X power amps he uses CRC filters on PSU, I guess the R stands for a resistor since he did not mention using a Thermistor.
At power-up the thermistor will get hot and the resistance will drop quite steeply but as soon as the caps are filled the temp will start to lower to the regular duty and so the resistance will start to creep up, I guess in not a very ordely way and may be with a lot of noise. Moreover, I think that thermistors will differ quite a lot from sample to sample from its temp/resistance caracteristics so you may find that your + and - rail behave differently. I guess this is the last thing one may want to have on an AX.
I dont know who, but someone posted a link to KC00X thermistors spec sheet in this or other thread, you may want to check the tolerances for this devices.
Also, NP indicated that on some of Pass Labs X power amps he uses CRC filters on PSU, I guess the R stands for a resistor since he did not mention using a Thermistor.
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Joined 2002
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Joined 2002
Hi Peter
Very glad to read that you have solved the trouble.
The first impression of yours about the sound is similar as mine with XSOZV2.
I like the sound more and more, time after time.
I really hope to read the full description of the sound of your Aleph-X.
I am pretty sure you could write it down in a professional manner.
By the way, what is your pre? Sorry, I do not remember well…
JH
Very glad to read that you have solved the trouble.
The first impression of yours about the sound is similar as mine with XSOZV2.
I like the sound more and more, time after time.
I really hope to read the full description of the sound of your Aleph-X.
I am pretty sure you could write it down in a professional manner.
By the way, what is your pre? Sorry, I do not remember well…
JH
Thank you Peter, as you can see I am quite new on this forum, unfortunately I discover it when I was finishing my Aleph 4 and thought it was to late to change the project to the X series.
I might in the near future.
I have gone through many threads, and of course I have spent many hours going through the Aleph x but there are more than 1000 posts! As most of you fellow members I am here also to learn from the collective ideas, projects and opinions. For the record I'm not an EE, just having a ball as a DIY.
I might in the near future.
I have gone through many threads, and of course I have spent many hours going through the Aleph x but there are more than 1000 posts! As most of you fellow members I am here also to learn from the collective ideas, projects and opinions. For the record I'm not an EE, just having a ball as a DIY.
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