XAB Measurements

DarkOne · 12th April 2006, 04:48 PM

Hi All,
This is an update to my previous thread about my amplifier. Description can be found in this thread
Measurements were taken with sound card ESI Juli@.
Feel free to comment.

I forgot to mention that I named amplifier XAB because it runs in heavily biased class AB and uses Pass' X patent.

So, I'll start with spectrum of 1kHz sinewave to 10ohm (couldn't find other power resistor at home) at 5W

DarkOne · 12th April 2006, 04:49 PM

1kHz 35W

DarkOne · 12th April 2006, 04:51 PM

1kHz square wave to 10ohm parael with 1uF capacitor at 25W

DarkOne · 12th April 2006, 04:52 PM

10kHz square wave at 25W to 10ohm and 1uF parael

Please note that also output from sound card is not perfect, but I hope this is enoug.

Nelson Pass · 12th April 2006, 06:00 PM

That's really excellent.

DarkOne · 13th April 2006, 05:07 AM

Quote:

Originally posted by Nelson Pass
That's really excellent.

Thanks a lot

flg · 13th April 2006, 07:26 PM

Yes, Congrats. I remember the original post and the amp. I have the pics in my "Class A" folder. I liked this design. I remember N.P. made a good comment or two back then also. Happy to here it's working out well for you. Keep it up!

DarkOne · 14th April 2006, 08:58 AM

Thanks flg

I have few modifications prepared for the final version (amp is still in prototype stage). So I hope the amp will be even better.

1st - I'll try to cascode input diff. transistors. According to simulations, it can reduce higher order THD components. Also PSRR should be better. If not, I can eliminate it from PCB without much modifications.

2nd - These measurements were taken from amplifier, which did not use degeneration resistors on sources of diff pairs. I'm going to use 47R. If there's no success, I can bypass them anytime.

3rd - Currently every chanel is on 3 PCBs wired together with ribbon cable (practical, but not reliable). One chanel already damaged due to wrong connection. So new version (final one, I hope) will be on 1 PCB to avoid problems.

I'll post complete schematics with component values and PCB layout in few months, stay tuned.

flg · 14th April 2006, 07:03 PM

Yes, I tend to have a few proto boards to many by the time something works good...
Earlier you commented on your measurement set, ESI Juli@ sound card ??? Could you elaborate. I have some equipment but I just rcently downloaded some software (RTA & RMAA) for use on my E-MU card. I was initially impressed. But I deceided I needed to vacuum the floor before crawling around doing the cable thing. Well, I must have bumped the putor with the vacuum because I lost a chunk of the OS on disc and had to rebuild the putor with a few new components...
Yes, The Amp, another alternative to more components might be to raise the voltage as high as possible. Basically, the curve gets bigger but the swing stays the same and is little more linear. Just an idea.
If you run a BOSOZ at + & - 100V it works even better!

PMA · 14th April 2006, 08:56 PM

DarkOne,

do you really find it excellent?

Regards,
Pavel

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12th April 2006, 06:00 PM	#5
Nelson Pass The one and only Join Date: Mar 2001	That's really excellent.

13th April 2006, 07:26 PM	#7
flg diyAudio Member Join Date: Jul 2005 Location: North East	Yes, Congrats. I remember the original post and the amp. I have the pics in my "Class A" folder. I liked this design. I remember N.P. made a good comment or two back then also. Happy to here it's working out well for you. Keep it up!

14th April 2006, 08:58 AM	#8
DarkOne diyAudio Member Join Date: Oct 2001 Location: Bratislava	Thanks flg I have few modifications prepared for the final version (amp is still in prototype stage). So I hope the amp will be even better. 1st - I'll try to cascode input diff. transistors. According to simulations, it can reduce higher order THD components. Also PSRR should be better. If not, I can eliminate it from PCB without much modifications. 2nd - These measurements were taken from amplifier, which did not use degeneration resistors on sources of diff pairs. I'm going to use 47R. If there's no success, I can bypass them anytime. 3rd - Currently every chanel is on 3 PCBs wired together with ribbon cable (practical, but not reliable). One chanel already damaged due to wrong connection. So new version (final one, I hope) will be on 1 PCB to avoid problems. I'll post complete schematics with component values and PCB layout in few months, stay tuned.

14th April 2006, 07:03 PM	#9
flg diyAudio Member Join Date: Jul 2005 Location: North East	Yes, I tend to have a few proto boards to many by the time something works good... Earlier you commented on your measurement set, ESI Juli@ sound card ??? Could you elaborate. I have some equipment but I just rcently downloaded some software (RTA & RMAA) for use on my E-MU card. I was initially impressed. But I deceided I needed to vacuum the floor before crawling around doing the cable thing. Well, I must have bumped the putor with the vacuum because I lost a chunk of the OS on disc and had to rebuild the putor with a few new components... Yes, The Amp, another alternative to more components might be to raise the voltage as high as possible. Basically, the curve gets bigger but the swing stays the same and is little more linear. Just an idea. If you run a BOSOZ at + & - 100V it works even better!

14th April 2006, 08:56 PM	#10
PMA diyAudio Member Join Date: Apr 2002 Location: Prague, Kitakyushu, Fukuoka	DarkOne, do you really find it excellent? Regards, Pavel