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 Post subject: JLH diy amplifier
PostPosted: 02 Feb 2017, 17:31 
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Joined: 31 Dec 2008, 15:34
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i've always heard the JLH 1969 cl. A amp mentioned as a good amplifier, so i were thinking about ordering a pair of diy kits on ebay. It seems there are a lot of differens between component quality of those kits sold on ebay. the one i've found, it seems the seller actually has done some thoughts about the components ...if you guys in the forum disagree, i would like to hear about it, before i'm going to order. feel free to tell here.

also an important question, is it necessary to use a regulated psu ? or will it work with an ordinary well filtered psu, as in the picture below ?

Ebay kit: JLH 1969



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 Post subject: Re: JLH diy amplifier
PostPosted: 05 Feb 2017, 11:28 
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Joined: 28 May 2008, 21:53
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Location: Winnipeg, CANADA
There is a good background by Nelson Pass on the JLH in this article: http://6moons.com/industryfeatures/zen/plh.pdf

And this site has the most info on the JLH amp circuit: http://sound-au.com/tcaas/index-1.htm

The original JLH amplifier used a smoothing circuit in the power supply.

As far as ebay kits go, that one looks pretty good. The transistors look decent.

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 Post subject: Re: JLH diy amplifier
PostPosted: 06 Feb 2017, 02:50 
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Gio wrote:
There is a good background by Nelson Pass on the JLH in this article: http://6moons.com/industryfeatures/zen/plh.pdf

This site has the most info on this circuit: http://sound-au.com/tcaas/index-1.htm

The original used a smoothing circuit in the power supply.

As far as ebay kits go, that one looks pretty good. The transistors look decent.


thanks :up:

i've often been into exactly those links and been very confused, because there's a lot of different variations of the jlh amp. okay, no more confussion, i'm just going to order this ebay kit.


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 Post subject: Re: JLH diy amplifier
PostPosted: 06 Feb 2017, 13:53 
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You should be good close with the proposed supply. The circuit is push-pull, so the PSRR won't be as awful as SE, but it is a class A design, so you will need a robust and quiet supply to keep unwanted noise down.

As you noted, it looks like they did a good job (judging by looks) with their choice of transistors and the multiturn (Bournes) pots.

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 Post subject: Re: JLH diy amplifier
PostPosted: 11 Feb 2017, 08:04 
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thanks gio


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 Post subject: Re: JLH diy amplifier
PostPosted: 23 Feb 2017, 17:17 
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I'd sugest that you change the output capacitor to a audio capacitor for better sound quality.
Also If you can get 40 000uF of more capacitors for the build it should be allright.
On the otherhand regulators may give better perfomance but may cost more than putting extra capacitors in the build.


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 Post subject: Re: JLH diy amplifier
PostPosted: 27 Feb 2017, 11:00 
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KochiyaYamato wrote:
I'd sugest that you change the output capacitor to a audio capacitor for better sound quality.
Also If you can get 40 000uF of more capacitors for the build it should be allright.
On the otherhand regulators may give better perfomance but may cost more than putting extra capacitors in the build.


thanks Kochiya i'll try a better quality of output cap. also no problem with a large bank of caps for the ps, i could give it ½ F if needed :thumbsup:


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