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Old 26th February 2012, 10:11 PM   #2001
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Quote:
Originally Posted by Esperado View Post
... As long are they are not burned in short circuit !
Hopefully not

Sometimes fuses saves the day

Well I practice this kind of solution for more than 10 years and there's no way to go back to output relay anymore. The same with voltage feedback.

BTW 2000 posts were written in this thread.
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Old 26th February 2012, 10:25 PM   #2002
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Quote:
Originally Posted by a.wayne View Post
LC.

Great looking chassis and layout , a couple questions , what is the 4 pin locking connector for ? Any issues with the transformers being so close ?
4-pin connector conducts 12 V remote trigger input/output signals if connected, so an amp can be turned on by multichannel preamp or similar and at the same time when on sends the on trigger signal to another amp etc. Trigger input is galvanicaly isolated from any amp's potential, even earth connection, to prevent any interference currents inside the system (HT, stereo, etc.).

So far no issue regarding transformers position. Some DIY-ers even stuck toroids without any issue. Because on non-ferrite material of the AL-heatsinks there is none magnetic short connection between transformers.
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Old 27th February 2012, 12:33 AM   #2003
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Quote:
Originally Posted by Lazy Cat View Post
Sometimes fuses saves the day
Did-you make the screw driver test at 1, 10, 100 watts ? (Big sparkles)
Well, i must agree that, since i managed a big PA system, i'm pretty paranoid.

I must admit that your solution is enough for a domestic use. But it would be better with my way to detect abnormal situations, witch is instant, comparing to your.
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Last edited by Esperado; 27th February 2012 at 12:36 AM.
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Old 28th February 2012, 11:20 AM   #2004
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LC, Is there any good substitute for 2sa1209/2sc2911 ? it seems had stop production, and almost all places out of stocked. (those have stock seems suspicious website) Had find for long time but not much result I have here.
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Old 28th February 2012, 12:21 PM   #2005
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LC, is it possible to use MJE15032/33/34/35 for cascode BC550C/560C VAS ? OR MJL3281/1302 (seems wasting)
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Old 28th February 2012, 12:59 PM   #2006
Salas is offline Salas  Greece
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Quote:
Originally Posted by Sheldon View Post
If I abandon the Thermaltraks and go with Nico's FET version, are these values OK? Retain 2SA/SC drivers, or use BC550/60? Leave or remove the driver emitter resistors?

I assume the drivers are run at lower current levels than for the BJT version. Am also assuming this version will be easier to stabilize for temp drift.

Sheldon
550/560 are much OK for input, but avoid for drivers, they may die during bias drifts in test phase many times, Vceo not enough for full swing also. Emitter resistors on drivers did not play a key stabilization role, those were BD139/140 I had experience with though, maybe doing better for your 2SA1360/2SC3423.
Yes they can run <5mA and the amp still be fast. You may need other than 330R to turn the drivers on at the current you want. Don't assume that is too easy to stabilize VS BJT OPT though. That 330R between the output Mosfet gates need be something more elaborate IMHO, there it was a pain to keep bias in mine. Maybe a Vbe multiplier, but have your own test go to see also.
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Old 28th February 2012, 01:06 PM   #2007
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Hi,

Can you please point me to Nico's Lateral Mosfet final schematics?

Thank you.
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Old 28th February 2012, 02:15 PM   #2008
Salas is offline Salas  Greece
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Here's Nico's Simple Symetrical Amplifier
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Old 28th February 2012, 02:50 PM   #2009
PauloPT is offline PauloPT  Portugal
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Thank you, Salas.

Is this circuit stable? I tried to simulate it and I get huge distortion unless I set VR1 to less than 300 ohm, that is, more than 3 A bias.

Thanks.
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Old 28th February 2012, 02:57 PM   #2010
Salas is offline Salas  Greece
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That is Nico's to answer. Me I modified it a lot.
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