F5 power amplifier

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#3,202
Levinson and and others use regulated supplies in power amps
If you want to go with the extra fuss thats fine. Capacitance multipliers are spiffy too. But I fear we maybe digressing a bit from the real subject here ( the F5).

Anyone able to compare F5 to an Aleph?
 
#3,209
azarek said:
Welcome

I need an adwise

It is possible to drive my 4 ohm speakers (ALR Entry 4) by this nice amplifier?

Thanks
Adam
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My ESLs are declared as 4 Ohm, but do give a very hard time to any "average" AB class amp. The impedance can and does drown most of the available 4-16Ohm amps, but no problems with the F5. Highly recommended amp to pick for DIY...
😀
 
#3,211
Re: jfet matching?

merlin2069er said:

how many transistors would I have to order to nominally match Q1 & Q2 together?
or is it at all necessary?
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The minimum would be 2 of each, but that also would be as likely as winning the jack pot on national lottery
:clown:

The practice is to make a group buy and have 100 of each to get as many nominally matched pairs. With just a tiny bit of luck, from 2x100 you might squeeze 100 pairs... I bought several matched pairs and the matched ones are marked within range of 113 up to 154 for matched pairs/quads

Actually, I know some who built the F5 with merely picking them from a pile and had no problems, but I prefer to follow the instructions... 😀
 
#3,216
Probably so, since you don't do Class A unless you really care about quality.
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Thank you for answering to my stupid question, Mr Pass.
Since psu capacitors directly feed the current into the loudspeaker they need, of coarse, to be low ESR.
My first thought was: why low esr since the psu feeds a constant current? But, happily, capacitors do not feed a constant current into the speaker
I need to think more, next time, before aking a question.I apologise.🙂
 
#3,220
I believe I read earlier in this thread that ther was no much point in trying to match the sk and sj parts..... just like there was no much point in matching the N and P mosfet either. I just went ahead and used whatever came out of the packet first. Amp sounds great, DC is <10mV and thats with no thermal compensation circuit in place and with no current limiting etc either.

I haven't done any measurements... actually I wouldn;t mind setting up to do some. I have a scope and a simple signal generator. I must have a go at it and see what results I get. It would be interesting to see how it works out. Directions willingly accepted from those who know.....


Fran

EDIT: I had a few (audio) friends over a week or 2 ago and all were very impressed by the F5. One remarked he thought it was as good as you could get from SS. At the moment I have a very fine KT88 amp, an airtight ATM2 in my system after repairing it for a friend. Over the weekend I intend to A/B it against the F5 and then also take my F5 to my friends and A/b against the F5 there with different speakers. I don't expect to come away embarassed...
 
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