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04dgmsilv 31st July 2008 12:38 AM

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?

http://lh5.ggpht.com/04dgmsilv/SJD36...0/IMG_1109.JPG

http://lh5.ggpht.com/04dgmsilv/SJD36...0/IMG_1089.JPG

http://lh6.ggpht.com/04dgmsilv/SJD37...0/IMG_1091.JPG

http://lh6.ggpht.com/04dgmsilv/SJD37...0/IMG_1093.JPG

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 01:10 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 09:25 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! :cool:

04dgmsilv 31st July 2008 01:01 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 01:24 PM

Very nice

Zen Mod 31st July 2008 01:31 PM

veery fugly !

:clown:

04dgmsilv 30th August 2008 12:15 AM

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 01:38 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 01:17 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!:D )

Nelson Pass 31st August 2008 02:26 AM

I'm sure it will be fine.

:cool:


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