zen and irfp240

nightdrg · 9th November 2003, 01:01 PM

Hi,
I'm newbie in audio and i'm working with Zen first variation. I use IRFP240 instead of IRFP140 (i can't find IRFP140 in my country). After a few seconds R1 (0R33/2W) is really hot and it smokes. I take 2R0/5W inestead of it. Now i have about 1.1V on R1. Is it OK? Or should i change R6/R7?

regards,
pawel.

B.L. · 9th November 2003, 11:47 PM

I can find IRFP140 for You

moe29 · 10th November 2003, 01:36 AM

Make sure that P1 (the potentiometer) is set at half or less when
you power up the amp. If it is at full that will cause what happened
to you - and probably toast your FETs too.

nightdrg · 10th November 2003, 08:14 PM

Mhm, and it is good idea to use R1=2 Ohm instead of .33?

moe29 · 10th November 2003, 10:50 PM

A value of 0.33 ohm, 2 watts for R1 works - if the circuit has been
correctly assembled. Other parts will work, as Mr. Pass mentions
in the article, but i would say it's probably best to stick as close as
you can to the parts list for your first build. After you have a
working amp, feel free to experiment from that point

- A good
place to start would be the upgrades reccomended in the
Zen Revisited article that can be found on the PassDiy web site.

MikeW · 11th November 2003, 02:24 AM

The voltage drop should be .66 volts. It is set by the base to emitter drop of Q3. The value of R0 (.47 ohm) and R1(1 ohm) set the bias. They are .33 ohms together it is .66/.33 or 2 amp bias. If R0 (2 ohm) and R1(1 ohm) that would be .66 volts/.66 ohms or 1 amp bias.
IRFP 240 should work fine. Good luck.

SGregory · 11th November 2003, 02:30 AM

From my personal experience I would check the orientation of Q3. I'll be darned if I screwed that up twice. I burned R1 and lost fets until I realized that the circuit wasn't regulating the current properly.

nightdrg · 11th November 2003, 09:15 AM

Quote:

The voltage drop should be .66 volts. It is set by the base to emitter drop of Q3. The value of R0 (.47 ohm) and R1(1 ohm) set the bias.

I don't have R0 yet because it isn't in the zenamp.pdf.

So should i insert it somewhere?

MikeW · 11th November 2003, 04:57 PM

http://www.passdiy.com/projects/zenv4-3.htm

This is V4?

nightdrg · 11th November 2003, 05:02 PM

No, this is first zen project (www.passdiy.com/pdf/zenamp.pdf).

9th November 2003, 01:01 PM	#1
nightdrg diyAudio Member Join Date: Nov 2003 Location: Wroclaw/Poland	zen and irfp240 Hi, I'm newbie in audio and i'm working with Zen first variation. I use IRFP240 instead of IRFP140 (i can't find IRFP140 in my country). After a few seconds R1 (0R33/2W) is really hot and it smokes. I take 2R0/5W inestead of it. Now i have about 1.1V on R1. Is it OK? Or should i change R6/R7? regards, pawel.

11th November 2003, 02:24 AM	#6
MikeW diyAudio Member Join Date: Sep 2002 Location: North of Boston	Bias The voltage drop should be .66 volts. It is set by the base to emitter drop of Q3. The value of R0 (.47 ohm) and R1(1 ohm) set the bias. They are .33 ohms together it is .66/.33 or 2 amp bias. If R0 (2 ohm) and R1(1 ohm) that would be .66 volts/.66 ohms or 1 amp bias. IRFP 240 should work fine. Good luck. __________________ MikeW

11th November 2003, 04:57 PM	#9
MikeW diyAudio Member Join Date: Sep 2002 Location: North of Boston	V4? http://www.passdiy.com/projects/zenv4-3.htm This is V4? __________________ MikeW

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9th November 2003, 11:47 PM	#2
B.L. diyAudio Member Join Date: Apr 2003 Location: Nysa-Poland	I can find IRFP140 for You

10th November 2003, 01:36 AM	#3
moe29 diyAudio Member Join Date: Dec 2002 Location: Florida	Make sure that P1 (the potentiometer) is set at half or less when you power up the amp. If it is at full that will cause what happened to you - and probably toast your FETs too.

10th November 2003, 08:14 PM	#4
nightdrg diyAudio Member Join Date: Nov 2003 Location: Wroclaw/Poland	Mhm, and it is good idea to use R1=2 Ohm instead of .33?

10th November 2003, 10:50 PM	#5
moe29 diyAudio Member Join Date: Dec 2002 Location: Florida	A value of 0.33 ohm, 2 watts for R1 works - if the circuit has been correctly assembled. Other parts will work, as Mr. Pass mentions in the article, but i would say it's probably best to stick as close as you can to the parts list for your first build. After you have a working amp, feel free to experiment from that point - A good place to start would be the upgrades reccomended in the Zen Revisited article that can be found on the PassDiy web site.

11th November 2003, 02:30 AM	#7
SGregory Tubie Noobie diyAudio Member Join Date: Apr 2003 Location: Southern Tier NY	From my personal experience I would check the orientation of Q3. I'll be darned if I screwed that up twice. I burned R1 and lost fets until I realized that the circuit wasn't regulating the current properly.

11th November 2003, 05:02 PM	#10
nightdrg diyAudio Member Join Date: Nov 2003 Location: Wroclaw/Poland	No, this is first zen project (www.passdiy.com/pdf/zenamp.pdf).

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