Hi,
I just found a nice circuit for an amp.
Anyone built this?
Opinions on the design are welcome 🙂
Here is the link: http://www.arky.ru/audio/shem/hppa/hppa.htm
I just found a nice circuit for an amp.
Anyone built this?
Opinions on the design are welcome 🙂
Here is the link: http://www.arky.ru/audio/shem/hppa/hppa.htm
it looks nice but it also looks very complex. Why dont try the digi-125 from graham dicker. i can send you the files by e-mail if you want.
As discussed before in these forum, the HPPA by Bert Molenkamp is a good design. I built one for a friend to drive a pair of pro-speakers and it performed very well.
Cheers
Andrea
Cheers
Andrea
i am not comfortable with a trimpot on the emitters of the input long-tails.....there has to be a better way....
joan2 said:
There is. Those transistors are so cheap that you can buy
tonloads of them and match them.
It is a bit different for JFETs which vary more and are thus
harde/more costly to match. It is quite common to see a
trimpot in the same location even in well-reputed designs.
Since people always have so much to say about pots and
mostly discuss which is the least bad type, I am surprised
one seldom/never see any discussions on such trimpots.
In input section consisting in the manner of D. Self is simpler. Requires no trim pot and no voltage regulator. A CC source consistind of a small PNP two diodes and a couple of reisitors then. Then a PNP pair to form a differential amp (what you've already got) and you waqnt to go further put a current mirror Two NPN'sbewteen the input pair between the the input pair and the negative rail.
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