My F3 Clone

04dgmsilv · 30th July 2008, 11:38 PM

Well, like so many others, here is my first go at a DIY FirstWatt amp. I had previously build one of Peter Daniels GCs, but that is basically a kit. This one, I used PD's boards and some of his ideas from his ZV9, but beyond that its all my crazy ideas, which turned out fairly well, but I'm sure my next chassis will have better fit and finish...

Just recently got it up and running, so well see how it sounds over the next few weeks...

One question, what should I measure to assure P2 is adjusted equally from L to R channels?

If we have good weather this weekend, I will try and shoot some photos outside for better lighting.

Thanks for all the great info and especially to Mr. Pass for all the generosity.

Nelson Pass · 31st July 2008, 12:10 AM

Those are the nicest capacitor brackets I've ever seen.

I adjust P2 for gain. If you have an oscillator and voltmeter, you
can adjust the two channels for equal gain. Otherwise, just use a
fixed resistor.

Vix · 31st July 2008, 08:25 AM

Congratulations!

Very nice build. F3 is a very good sounding amplifier. I've built Zen V9 and I don't feel an urge for "another amp". This one makes me happy.

By the way, what preamp do you use? Even though F3 has a lowish gain ( about 12 db or so), since you are using highly efficient Zu Druids, I guess that a B1 buffer will be sufficient, and this combination may sound even better than the one with any preamp with gain.

Regards

Vix

p.s. Photos look very nice!

04dgmsilv · 31st July 2008, 12:01 PM

Thanks for the compliments. The cap bracket is nothing more than a 1x6 piece of red oak, all of the PS wiring is underneath. The transformers (dual mono) are hidden under a piece of 1/4" steel channel.

I am currently not running a preamp, my transporter serves as both source and attenuation. I am reading the B1 threads with interest, but my other thought is to have Modwright do thier mod on my transporter and continue running direct.

MikeW · 31st July 2008, 12:24 PM

Very nice

Zen Mod · 31st July 2008, 12:31 PM

veery fugly !

04dgmsilv · 29th August 2008, 11:15 PM

Well, its been running for about a month now, and it sounds very very good... Still some probably need to get some time on those BGs, but it is a very nice match with the druids.

Quick question on the heat sink, how hot is too hot?

I have a raytek temp gun and after letting it run for a few hours the temp on and around the IRFP transistors is 160F or a bit more if the amp if just idleing. The external (fin) area of the HS runs around 125F.

Thanks,
Dan

cfcubed · 30th August 2008, 12:38 AM

Quote:

Originally posted by 04dgmsilv
<snip>
Quick question on the heat sink, how hot is too hot?

I have a raytek temp gun and after letting it run for a few hours the temp on and around the IRFP transistors is 160F or a bit more if the amp if just idleing. The external (fin) area of the HS runs around 125F.

No expert here for sure, but I've been told not to worry too much about it.

And maybe you saw the scale here - "How Much Heat Sink?"

04dgmsilv · 30th August 2008, 12:17 PM

Thanks, I did look at the calculators, etc. when picking the amount of heat sink, but did not see that last page. I am in the bloody hot range for sure! I'm not overly concerned, b/c it sounds soooo good (plus I have spare parts!

)

Nelson Pass · 31st August 2008, 01:26 AM

I'm sure it will be fine.

30th July 2008, 11:38 PM	#1
04dgmsilv diyAudio Member Join Date: Jun 2006	My F3 Clone Well, like so many others, here is my first go at a DIY FirstWatt amp. I had previously build one of Peter Daniels GCs, but that is basically a kit. This one, I used PD's boards and some of his ideas from his ZV9, but beyond that its all my crazy ideas, which turned out fairly well, but I'm sure my next chassis will have better fit and finish... Just recently got it up and running, so well see how it sounds over the next few weeks... One question, what should I measure to assure P2 is adjusted equally from L to R channels? If we have good weather this weekend, I will try and shoot some photos outside for better lighting. Thanks for all the great info and especially to Mr. Pass for all the generosity.

31st July 2008, 12:24 PM	#5
MikeW diyAudio Member Join Date: Sep 2002 Location: North of Boston	Very nice __________________ MikeW

31st July 2008, 12:31 PM	#6
Zen Mod diyAudio Member Join Date: Jan 2003 Location: ancient Batsch , behind Iron Curtain	veery fugly ! __________________ my Papa is smarter than your Nelson ! tnx to clean thread ; Cook Book ; PSM LS Cook Book ; Baby Diyaudio FORUM ; Mighty ZM's Bloggg;I'm dumb

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31st July 2008, 12:10 AM	#2
Nelson Pass The one and only Join Date: Mar 2001	Those are the nicest capacitor brackets I've ever seen. I adjust P2 for gain. If you have an oscillator and voltmeter, you can adjust the two channels for equal gain. Otherwise, just use a fixed resistor.

31st July 2008, 08:25 AM	#3
Vix diyAudio Member Join Date: Nov 2003 Location: Somewhere on Planet Earth	Congratulations! Very nice build. F3 is a very good sounding amplifier. I've built Zen V9 and I don't feel an urge for "another amp". This one makes me happy. By the way, what preamp do you use? Even though F3 has a lowish gain ( about 12 db or so), since you are using highly efficient Zu Druids, I guess that a B1 buffer will be sufficient, and this combination may sound even better than the one with any preamp with gain. Regards Vix p.s. Photos look very nice!

31st July 2008, 12:01 PM	#4
04dgmsilv diyAudio Member Join Date: Jun 2006	Thanks for the compliments. The cap bracket is nothing more than a 1x6 piece of red oak, all of the PS wiring is underneath. The transformers (dual mono) are hidden under a piece of 1/4" steel channel. I am currently not running a preamp, my transporter serves as both source and attenuation. I am reading the B1 threads with interest, but my other thought is to have Modwright do thier mod on my transporter and continue running direct.

29th August 2008, 11:15 PM	#7
04dgmsilv diyAudio Member Join Date: Jun 2006	Well, its been running for about a month now, and it sounds very very good... Still some probably need to get some time on those BGs, but it is a very nice match with the druids. Quick question on the heat sink, how hot is too hot? I have a raytek temp gun and after letting it run for a few hours the temp on and around the IRFP transistors is 160F or a bit more if the amp if just idleing. The external (fin) area of the HS runs around 125F. Thanks, Dan

30th August 2008, 12:17 PM	#9
04dgmsilv diyAudio Member Join Date: Jun 2006	Thanks, I did look at the calculators, etc. when picking the amount of heat sink, but did not see that last page. I am in the bloody hot range for sure! I'm not overly concerned, b/c it sounds soooo good (plus I have spare parts! )

31st August 2008, 01:26 AM	#10
Nelson Pass The one and only Join Date: Mar 2001	I'm sure it will be fine.

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