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Old 23rd October 2008, 02:39 PM   #1911
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Quote:
Originally posted by Babowana



Many F5 builders confirm that the F5 sound is great.
You could use any good quality of transformer.

Cheers,

I confirm its a great amplifier , better with the thermistors .
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Old 23rd October 2008, 02:42 PM   #1912
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I have built 4 of them -- they sound great.

I don't know if the thermistors make them sound better, per se, but they are easier to adjust and have slightly lower THD+N% than the non-thermistor version.
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Old 23rd October 2008, 04:34 PM   #1913
stein2 is offline stein2  Serbia
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One more confirmation to support the capability to play music in an extraordinary manner. Not just a technically well designed piece of hardware, but also a good amp which finally was capable of bringing out the best out of my Philips CD303 (combined with modified NS10 clone and "Shiny" Shunt regulated power supply). It easily drives my ESL panels which made use of almost any other amplifier "Mission Impossible" (if less than 100WRMS) This amp has "only" 25W in Class A and even with a fairly modest dissipation it can cope with anything I tried to listen to. A good choice, one of the best "bangs" for the buck... I have a 500VA toroid with 4x18V secondaries (18VAC)
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Old 23rd October 2008, 05:10 PM   #1914
EUVL is offline EUVL  Europe
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> Really, Jest 4A,
> so it will do only about 10W?

My balanced version has +/-16V rails and 4A per channel total bias. More the transistors won't take.

Leaving at least 4V Vds for the MOSFETs, I get max swing 24V (as it is balanced output) and 4A. This is set to peak for 6 ohm speakers, giving 48W (rms) assuming sine wave.

For 4 ohm, it will be 32W (current limiting) and for 8 ohm, 36W (voltage limiting).
No idea how you come to 10W.


Regards,
Patrick
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Old 23rd October 2008, 09:55 PM   #1915
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Quote:
Originally posted by EUVL
My balanced version has +/-16V rails and 4A per channel total bias. More the transistors won't take.
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Old 23rd October 2008, 11:15 PM   #1916
Luke is offline Luke  New Zealand
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Quote:
Avoid the cheap Jaycar, etc trannie - better to spend some $s.
Hi James, I use these transformers for availability price etc. Are they really so bad?

Also, where would you get good transformers in this part of the world that dont hum?
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Old 24th October 2008, 12:01 AM   #1917
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Nah Luke,

They're not that bad, just built for minimum cost - just "up-the-size" about 50%. For a better result, go for a simple EI frame with two secondaries for reasonable $s - plenty folks over there build good transformers - ask Beau of "Mosquito" thread.

Torroid? Possibly the best torroids available today is from "Harbuch" in Sydney and quite reasonable cost - big tho'!

Better results with the 240v/50Hz single primary, not the 110v dual primary, 60Hz ones (they're made for exactly that!)

I doubt that line Noise or the DC component is a big problem in NZ, but power filters and DC trap are easy enough.

Also, use U/fast diodes (< 20nS) - makes BIG difference.
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Old 24th October 2008, 12:17 AM   #1918
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Default Transformers

Luke,


RS Components sell transformers:

http://newzealand.rs-online.com/web/...2238162#header

This is what I'll be using, I have used 4 Transformers from RS and all this brand, without any problems.


Brett

If you spend $100 they'll give you free delivery so make a decent order first.
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Old 24th October 2008, 03:37 AM   #1919
Wasim is offline Wasim  Pakistan
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Hi All,

Thanks for the reply. Can I use 5k thermistors rather than 4.7k because the 5k thermistors are available here?

Reg
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Old 24th October 2008, 04:23 AM   #1920
EUVL is offline EUVL  Europe
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>

Why?
Because of +/-16V 2A (I just copied from Grey's Aleph-X) ?
Or because I said the transistor won't take more ?

They are already dissipating 32W continuous. I know they can in theory take more, maybe up to 50W with good thermal management, but reliability drops.

Or you are suggesting 32W is already too much ?


Patrick
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