10-20W Claa-A..which one ?? - diyAudio
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Old 27th January 2004, 07:40 PM   #1
AuroraB is offline AuroraB  Norway
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Question 10-20W Claa-A..which one ??

An aquaintance of mine have asked me to assist in choosing and building a 10-20 W class A. The most likely candidates seems to be the JLH (with variations), the Mini-A and the Hiraga/ Classe.
The are all reasonably comparable in terms of component count and cost, although the original Hiraga semi's are getting more obscure by the day. The thread of the JLH is quickly aproaching a lightyears length without any sonic conclusion. Which are your favourites, built and tested??
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Old 27th January 2004, 07:55 PM   #2
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Default Re: 10-20W Claa-A..which one ??

Quote:
Originally posted by AuroraB
Which are your favourites, built and tested??
I have only built the 1969 jlh, not any of the others you had mentioned. to me, jlh1969 is so simple, easy to put together and to get to work, offers reasonably good performance, and there is no reason not to try it if you are looking for amps in the 10-20w range.

I haven't built the 1996 version of the jlh but thought the 1969 is good enough and pretty versatile. I have zero problem with hum, thump, and other issues people have encountered.

I also highly recommend the mosfet version of the 1969jlh. it seems to more lively than the bjt version and faster in measurement and simulations.

But either way, it is one simple amp that offers performance good enough for most of us.
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Old 27th January 2004, 11:13 PM   #3
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The 1969 JLH amp was the first 'proper' power amp I ever built, the last version being a pair of mono units with DC coupled output stages (now living in the loft).

I don't think there's much justification for building this design now since there are plenty of superior contemporary designs available that are just as easy if not easier to build and of similar cost.

The most notable 'issues' with the JLH (at least the ones I built)were poor DC offset and bias stability as well as low PSRR.
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Old 27th January 2004, 11:16 PM   #4
Fuling is offline Fuling  Sweden
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I would suggest the Mini-A.
Good sounding, easy to build, easy to adjust to whatever parts that is available.
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Old 31st January 2004, 12:13 PM   #5
Tyimo is offline Tyimo  Hungary
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Millwood!
Could you show me which mosfet variation of the 1969JLH do you use?
I built the standard 1969 with MJ15003 and it is great, but I would like to try with Mosfet too.
Thanks
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Old 31st January 2004, 12:20 PM   #6
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Default Which ?

Build PMA's A - 2 . Sound super !
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Old 31st January 2004, 01:10 PM   #7
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Quote:
Originally posted by Tyimo
Millwood!
Could you show me which mosfet variation of the 1969JLH do you use?

the basic schematic is here:

http://www.diyaudio.com/forums/showt...348#post289348

the real one I am running now actually has a mosfet as driver (in place of the mje). the mosfet driver version doesn't sound better than the bjt driver version (probably worse performance in thd) but makes me feel better, .

I am not sure if it will work with other types of mosfets but it definitely works very well with the irfs.

be forwarned tho. that turn-on thump (current in-rush on the mosfets) can be quite high, tho. it does not produce any audioable thump on the speaker. mine can reach 5 - 6 amps (idling at about 1.5amp). I have not been able to fix it.

Enjoy and let us know how it works.
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Old 3rd February 2004, 07:50 PM   #8
Tyimo is offline Tyimo  Hungary
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Thanks Millwood!
I will try soon!
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