Spent a good chunk of today with the ax-11 today. It is hooked up to my aikido preamp running 6cg7/6cg7. Speakers are a pair of 2 ways very similar to the sr71 from zaph audio.
Again I can't stress how quiet this amp is. Sound is very transparent with generous bass, maybe going deeper than the ax14. This one will stay in the rotation for a while.
Yes I paralleled a 15k resistor on the 3k2 getting about 2640. 2k2 wasn't enough to turn them on and 3k2 was way too much....measured to almost 1A and shut it down.
After all day today measured 35mV across the 0.22 ohm so it is very stable.
***Edit...I used 3k2 in the board...not the 2k2 you updated your silkscreen to and paralleled that to reduce from 3k2.
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I was checking and I found out that the 2N5551 the pin orientation I copied wrongly from mister Willy's original one, I don't thing is a big problem the only thing I have to do is to rotate 180 degrees or use BC546 because it has the correct orientation, I guess mister Willy has to check it too no big deal we can fix it, thank you for let us know I appreciated sir.
Regards
Juan
Regards
Juan
Attachments
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ax11
post #2366 left diagramme
post #2383 left photo multiturn 10k trimmer ,bias adjustment
hope this help.
See post #2390
post #2366 left diagramme
post #2383 left photo multiturn 10k trimmer ,bias adjustment
hope this help.
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Were you able to get it stable? I thought I remember reading that you were having trouble keeping it stable with the trimmer. I like the idea of using a trimmer.
ax11
Take a look here.http://www.youtube.com/watch?v=q0q5eUH0gZE
It's absolutely stable on rail+/-35V.
Take a look here.http://www.youtube.com/watch?v=q0q5eUH0gZE
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Pay attention not to turn trimmer at lower resistant point or put a standard resistant in series with this.
good luck.
So running 35mV @ 160mA per device I took a couple output measurements.
Now my DMM has a crest feature so I loaded up some bass heavy music and cranked it up, my speakers are 4 ohm. The crest measurement after a minute or 2 was 21V.
21/4 = 5.25A
5.25A X 21V = 110W
Very rudimentary and seat of the pants but I am impressed that this little amp is capable of 100W of clear power...no distortion.
I swapped the input tubes to the highest gain tube I had which is 6n1p. With 6dj8 I only got 18V. The 6n1p gave it that extra oomph to go above 100W.
Good stuff!!!
Now my DMM has a crest feature so I loaded up some bass heavy music and cranked it up, my speakers are 4 ohm. The crest measurement after a minute or 2 was 21V.
21/4 = 5.25A
5.25A X 21V = 110W
Very rudimentary and seat of the pants but I am impressed that this little amp is capable of 100W of clear power...no distortion.
I swapped the input tubes to the highest gain tube I had which is 6n1p. With 6dj8 I only got 18V. The 6n1p gave it that extra oomph to go above 100W.
Good stuff!!!
As far as other DIY amps I have a small collection of DIY amps that go in and out of rotation:
SimpleSE - Tubelab
PP EL84 based upon a Broskie article at Tubecad Journal
The Moskido - Aikido front end with MOSFET power stage Class A
Pass Labs F5 - modified with dual outputs
Apex AX14
APex AX11
Symasym - dual output version from a GB here
I have built a few others and ended up abandoning them for various reasons and re-using parts for some of the above builds.
Anyways the AX11 really impresses me with its sound. It really reminds me of the SimpleSE the most from an overall sound standpoint. Much warmer than the Symasym and even the AX14. I like Class A power amps but in the summertime here in the Southern USA the heat can be a little much so it is nice having a cooler running option. I am using a chassis really designed for a 50 watt class A amp so it barely gets warm.
I am curious to be able to crank up the bias a little more in a stable manner and see what the results are.
The power supply I am using is a DIY version of the symasym PSU from Rudi's group buy using MUR680's and 4X10,000 uF. While not a regulated supply it is pretty quiet.
SimpleSE - Tubelab
PP EL84 based upon a Broskie article at Tubecad Journal
The Moskido - Aikido front end with MOSFET power stage Class A
Pass Labs F5 - modified with dual outputs
Apex AX14
APex AX11
Symasym - dual output version from a GB here
I have built a few others and ended up abandoning them for various reasons and re-using parts for some of the above builds.
Anyways the AX11 really impresses me with its sound. It really reminds me of the SimpleSE the most from an overall sound standpoint. Much warmer than the Symasym and even the AX14. I like Class A power amps but in the summertime here in the Southern USA the heat can be a little much so it is nice having a cooler running option. I am using a chassis really designed for a 50 watt class A amp so it barely gets warm.
I am curious to be able to crank up the bias a little more in a stable manner and see what the results are.
The power supply I am using is a DIY version of the symasym PSU from Rudi's group buy using MUR680's and 4X10,000 uF. While not a regulated supply it is pretty quiet.
