Zen 1 - Only one chanal is working!

seve · 31st August 2004, 11:46 PM

Hi,

I have just made a zen 1 around the pcb from audioxpress.

One channel seems to work. The rail is +32.9V. I have measured around 0.66V across R1. At the drains of the mosfets I have measured around 19V instead of the 17V metioned in the articel is this a problem? The DC at the output is 5mv. I stil have to get adjusted the P1.

The second chanal is not working. First time I powered this chanal up I had soldered the mosfet upside down so please tell me this have not destroyed something. I have now rewired this chanal, but I cannot get it to work! At the drains I see the rail voltage. Also the mosfets are not getting warm. Please help me solve the problem. How can I test that the mosfets are working?

Please bare with me this is the first amp I have made besides a gainclone!

Martin

Blues · 1st September 2004, 12:03 AM

Try replacing your mosfets...do a search and learn how to check them...very useful in troubleshooting.

Blues · 1st September 2004, 12:06 AM

oh...your first channel looks fine.

seve · 1st September 2004, 12:19 AM

Thanks for the reply. I actually did try to search but I could only find something about matching mosfets, but perhaps I used the wrong "words" when searching. Though I have just found a page by using google that might help me http://www.4qd.co.uk/serv/mostest.html .

I will try ordering some new mosfets for the chanal that is not working

Martin

seve · 1st September 2004, 01:43 PM

I think I have solved the problem! It was the P1 setting that was causing problems.....that's how it's when you don't understand how the amp is working ;-)

Now the second chanel is almost the same as the first. Only difference is a little higher rail and voltage at the drains. Dc at the output is 2mv.

So I hope the problem is solved. Now I just have to figure how to adjust the P1 correctly!

Martin

Blues · 2nd September 2004, 02:07 AM

adjust p1 while monitoring DC voltage across Q1's D-S...about 1/2 +2V of your rail voltage. Then you can sit back and enjoy...don't surrender that sweet spot to anyone

seve · 7th September 2004, 10:23 PM

Finally I got the time to test the zen :-).

I have only listen to it with one channel, because the amp is laying on a table, which are making it hard to power up both channels at the same time.

....but with even one channel it sounds great. The top and mid is just great, but the 10W for the bottom is perhaps a little low. At lower listening volume it's OK but when I turn up the volume I am missing a little Effect. Though I am not surprised by that as my speakers are not that sensitive. Still I am glad that I build the zen, because it was a good starting point before trying something more difficult. Untill I finish a alpeh-x, a regular alpeh or a zen v4 I can listen to the zen.

Thanks for the help goes to Nelson Pass for his papers and also Blues and Morten.

Martin

31st August 2004, 11:46 PM	#1
seve diyAudio Member Join Date: Sep 2002 Location: Denmark	Zen 1 - Only one chanal is working! Hi, I have just made a zen 1 around the pcb from audioxpress. One channel seems to work. The rail is +32.9V. I have measured around 0.66V across R1. At the drains of the mosfets I have measured around 19V instead of the 17V metioned in the articel is this a problem? The DC at the output is 5mv. I stil have to get adjusted the P1. The second chanal is not working. First time I powered this chanal up I had soldered the mosfet upside down so please tell me this have not destroyed something. I have now rewired this chanal, but I cannot get it to work! At the drains I see the rail voltage. Also the mosfets are not getting warm. Please help me solve the problem. How can I test that the mosfets are working? Please bare with me this is the first amp I have made besides a gainclone! Martin

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1st September 2004, 12:03 AM	#2
Blues Lightning In A Bottle diyAudio Member Join Date: Sep 2003 Location: Bremerton, WA	Try replacing your mosfets...do a search and learn how to check them...very useful in troubleshooting.

1st September 2004, 12:06 AM	#3
Blues Lightning In A Bottle diyAudio Member Join Date: Sep 2003 Location: Bremerton, WA	oh...your first channel looks fine.

1st September 2004, 12:19 AM	#4
seve diyAudio Member Join Date: Sep 2002 Location: Denmark	Thanks for the reply. I actually did try to search but I could only find something about matching mosfets, but perhaps I used the wrong "words" when searching. Though I have just found a page by using google that might help me http://www.4qd.co.uk/serv/mostest.html . I will try ordering some new mosfets for the chanal that is not working Martin

1st September 2004, 01:43 PM	#5
seve diyAudio Member Join Date: Sep 2002 Location: Denmark	I think I have solved the problem! It was the P1 setting that was causing problems.....that's how it's when you don't understand how the amp is working ;-) Now the second chanel is almost the same as the first. Only difference is a little higher rail and voltage at the drains. Dc at the output is 2mv. So I hope the problem is solved. Now I just have to figure how to adjust the P1 correctly! Martin

2nd September 2004, 02:07 AM	#6
Blues Lightning In A Bottle diyAudio Member Join Date: Sep 2003 Location: Bremerton, WA	adjust p1 while monitoring DC voltage across Q1's D-S...about 1/2 +2V of your rail voltage. Then you can sit back and enjoy...don't surrender that sweet spot to anyone

7th September 2004, 10:23 PM	#7
seve diyAudio Member Join Date: Sep 2002 Location: Denmark	Finally I got the time to test the zen :-). I have only listen to it with one channel, because the amp is laying on a table, which are making it hard to power up both channels at the same time. ....but with even one channel it sounds great. The top and mid is just great, but the 10W for the bottom is perhaps a little low. At lower listening volume it's OK but when I turn up the volume I am missing a little Effect. Though I am not surprised by that as my speakers are not that sensitive. Still I am glad that I build the zen, because it was a good starting point before trying something more difficult. Untill I finish a alpeh-x, a regular alpeh or a zen v4 I can listen to the zen. Thanks for the help goes to Nelson Pass for his papers and also Blues and Morten. Martin

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