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Old 5th November 2009, 10:04 PM   #11
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Thanks guys

OPAMPS......TO THE DUST PILE.

I think I may start with the F-5 to start with then.

Any tips before building starts ?
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Old 6th November 2009, 01:45 AM   #12
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will you be water cooling the F5? If you live fearlessly then by all means....I built it this way, it worked great until I biased up to 3A @ 35V. You can parallel the outputs...which in hindsight is what I should have done from the outset. There's a schematic floating around in the F5 thread somewhere about it.
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Old 6th November 2009, 01:49 AM   #13
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Originally Posted by Wizardmaxx View Post
Thanks guys

OPAMPS......TO THE DUST PILE.

I think I may start with the F-5 to start with then.

Any tips before building starts ?
I have to chuckle a bit. Op-amps are the standard when it comes to electronic crossovers. Many high end set-ups use electronic crossovers. I get zero complaints from my audio friends regarding my set-up.

Unless you build a discrete op-amp (and it won't come close to the specs of a commercial unit from what I've read) you're going to be listening to an op-amp somewhere in the audio chain... come to think of it, there's that CD player over yonder... and it's cousin, the DVD player... oh, let's not forget the Comcast box... my, but they sound pretty good to me.
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Old 6th November 2009, 07:02 AM   #14
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Originally Posted by MEGA-amp View Post
will you be water cooling the F5? If you live fearlessly then by all means....I built it this way, it worked great until I biased up to 3A @ 35V. You can parallel the outputs...which in hindsight is what I should have done from the outset. There's a schematic floating around in the F5 thread somewhere about it.
Well to be technically correct it's not watercooling....it's a non-conductive liquid called Feser One so we shall dub it F1cooling. Use it in my PC and works a treat. At full load (around 250w) runs at ambient plus 7 degrees.
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Old 6th November 2009, 08:40 AM   #15
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Maybe it is time to build your own DAC with discrete I/V stage. Nothing sounds better
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Old 6th November 2009, 11:04 AM   #16
AndrewT is offline AndrewT  Scotland
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Originally Posted by MEGA-amp View Post
water cooling the F5? ..............
.............it worked great until I biased up to 3A @ 35V...........
that is almost three times the designers recommended bias current.
A dissipation of 105W/Q cf 33W/Q is rank stupidity.
Did you look at the SOA of the devices you overloaded?
Did you calculate the reserve power to drive a load at that bias current?
Did you think

Maybe water cooling is a miracle worker!
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Old 6th November 2009, 12:54 PM   #17
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Quote:
Did you look at the SOA of the devices you overloaded?
skimmed over it, made a paper airplane out of it.

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Did you calculate the reserve power to drive a load at that bias current?
No calcs. Had 480,000uF, 1500VA transformer, then variac.


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Did you think
Totally over-rated. In the grand scheme of things, I did keep a fire extinguisher handy, so there was a least some thinking happening.

I knew full well it was on borrowed time, about 30 mins actually, and it sounded wonderful! Its DIY dude, if you're not blowing something up, you're not having fun. I did find some industrial cooling plates, so that definitely looks like the way to go.

Last edited by MEGA_amp; 6th November 2009 at 01:01 PM.
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Old 6th November 2009, 01:44 PM   #18
a.wayne is offline a.wayne  United States
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Originally Posted by thanh1973 View Post
Maybe it is time to build your own DAC with discrete I/V stage. Nothing sounds better
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Old 6th November 2009, 01:47 PM   #19
a.wayne is offline a.wayne  United States
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Quote:
Originally Posted by MEGA-amp View Post
skimmed over it, made a paper airplane out of it.


No calcs. Had 480,000uF, 1500VA transformer, then variac.



Totally over-rated. In the grand scheme of things, I did keep a fire extinguisher handy, so there was a least some thinking happening.

I knew full well it was on borrowed time, about 30 mins actually, and it sounded wonderful! Its DIY dude, if you're not blowing something up, you're not having fun. I did find some industrial cooling plates, so that definitely looks like the way to go.

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Old 8th November 2009, 10:28 AM   #20
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Originally Posted by MEGA-amp View Post
skimmed over it, made a paper airplane out of it.
I love that one.

It is all about having fun, just don't set your house on fire.
Have you started building another one yet?
Go with 3 pairs this time, and then you can crank it to 9A
Well maybe not 9A. 3A to 4A is a good number.
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