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Old 23rd August 2004, 11:30 AM   #1
polsol is offline polsol  South Africa
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Default JLH 10W Original

Thought I would resurect my interest in DIY audio by building the JLH 10W as a "reference" amplifier to judge future projects by. There have been many variants of this amp since '69 but is there any reason to adopt them rather than the original for my specific purpose?
Obviously the biggest problem with any electronic project is getting hold of the PCB. Are there any suppliers of a suitable, affordable PCB I can use?

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Old 23rd August 2004, 08:58 PM   #2
mikelm is offline mikelm  England
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Default Re: JLH 10W Original

Quote:
Originally posted by polsol
There have been many variants of this amp since '69 but is there any reason to adopt them rather than the original for my specific purpose?

Are there any suppliers of a suitable, affordable PCB I can use?

Regards,

Have you read through this thread ?

JLH 10 Watt class A amplifier

lots of info here and I think there might be boards or at least artwork.

watch out for Geoff's class A amplifier site - a goldmine

here is a link

http://www.tcaas.btinternet.co.uk/

but to answer your original question - If you build the original it may be quite easy to find better amps - however, if you build the latest version from the class A website you might have great difficulty in making or finding an amp that sounds better.

I know what my choice would be.

good luck

mike
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Old 24th August 2004, 03:15 AM   #3
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Default Search "Death of Zen", in ESP australian pages

This one is a "cousin" of the John Lindsey Hood design, you can find too BABE T.

The power will be low.... but you will see the class A amplifiers quality.

Many people, i am included, agree that those designs were the best sound reproduction amplifiers already made.

Some amplifiers, can match (beeing very good and kind with the others amplifiers) its performance... when those modern units, class AB units where reproducing low power....but when you increase the volume..... you will see that quality goes down.

This way, many good amplifiers can be wonderfull in low volume, you have many choices....but to hear applauses as applauses, not rain falling..... to listen to rain without confusing with steak making noise when reaching hot oil.... to hear cymbals without confusing it with glass bottles with different watter quantities... to bring the female voice to sing to you, 3 meters in front of you, or in your side..... have to go to class A, the simplest the amplifier is, the better the sound normally it produces.

Of course, subjective ideas, those things are different from people to people.....but more than 30 of forum people, those ones that already made JLH designs, agreed that it sounds very good!

regards,

Carlos
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Old 24th August 2004, 03:23 AM   #4
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Default Sometimes those boards you need are very expensive.

This way, you can buy two.... and you can tell the boards (joke, kidding) that one of them is a male board, and the other will be the female board.

You put them together in a dark place.... and wait some time....maybe those boards get married, and you can have reproduction...more boards.... one complete family!

Of course, people will think you send the board to someone copy! (joke).... you will say that the boards just reproduce.... you, really you, did nothing! (kiding)

Because those reproduction is against law... this way, better to go to some nature reproduction.

regards,

Carlos

Carlos
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Old 24th August 2004, 05:24 AM   #5
mikelm is offline mikelm  England
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yep - both of these designs are very similar to the JLH simple class but on the latest version on Geoff's class A site both the o/p and feedback capacitors have been designed out, along with the boot strap cct.

Removing the capacitors gives quite a big improvement across the whole audio spectrum.

here is the exact location

http://www.tcaas.btinternet.co.uk/jlhupdate.htm

mike
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Old 24th August 2004, 06:24 AM   #6
polsol is offline polsol  South Africa
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Default JLH Class A sans output capacitors

Thanks to all respondents.

Yes Mike I had read the DIY Audio thread and had also read the info on the Class A site (actually before "stumbling" across the DIYAudio site).
Problem is that there have been lots of variants for twin rail from JLH through to many others. Obviously all without the output cap but also with and without the bootstrap, with and without the feedback cap and with and without a ccs on the input transistor.
So, am confused (not quite dazed yet) as it is difficult to say whether some of the mods are beneficial and some may not be retrogressive. As we proceed from modification to modifcation I feel that this amp is now quite different to the original version as published in 1969 - which is why I had proposed to build the original.
However, if I can get a consensus (more or less as I know that subjectivity will probably provide an equal split) as to which one is a good starting point then I'll "go with the flow"!

I concur with many other comments that I have read in that simplicity is best and caps are, well, a nuisance. I remember a quip from JLH I read years ago in one of the audio mags that reffered to a "straight wire with gain" - and that's what I base my personal (audio) philosophy on.

Regards
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Old 24th August 2004, 07:43 AM   #7
mikelm is offline mikelm  England
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Well,

I guess it depends what you really want.

If you have time and money and want the knowledge that only comes from experience, you could start with 1969 and try all of the mods one at a time. This could take from a few months to a few years. It would be an interesting, rewarding and instructive process.

But my guess is that you end up prefering one of the latest versions ( providing you have a good front end ).

If you want to listen to a great sounding amp ASAP I guess you have to take a leap of faith and go with your interpretation of the reports that you have probably read here

http://www.tcaas.btinternet.co.uk/jlhsound.htm

over and out

mike
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