JLH 2003 Class A - how good is it?

Hi pumpweel,

Wondering how you went with your quest for DIY satisfaction...

I've built a few of these JLH'69 units.  The kits invariably use poor quality parts and I would avoid these completely.

My approach was to buy the bare boards online (AliExpress) and then source all the parts directly from 1st source suppliers.  The boards I purchased were 'AIYIWA' brand - surprisingly good quality (AliExpress description: "AIYIMA 2Pcs Hood 1969 Class A Audio Amplifier PCB Board Perfect 6 Tube Mute Version Bare PCB").

I then purchased components from Element14 / Mouser / Digikey / RS Components and built up the boards.  You're looking at ~120USD per built up amp (ie. ~240USD for a stereo pair).

These are 10W Class A amps, with capacitive coupled outputs.  They don't play loud nor low, but their midrange is immensely satisfying.

Nothing can replace the involvement of building your own equipment and if you're keen to do so, you'll most likely find it a satisfying experience.  As robejerman points out, though, the power transformer(s) - I used one per channel - and the casing will also need to be acquired and built up, but if you have the time and enthusiasm, go for and have fun while you do.

Ross

I have a full sized cost no object build of a JLH69 with fully regulated PSU + PEH169 caps. Very nice and not to be underestimated into Klipsch Heritage speakers. Sounds so ’right’ and one of my favourite amps.

can‘t for the life of me see how those small Chinese copies could possibly function with those tiny heatsinks - unless they run the output transistors below spec. They need a large surface area.

Hi pesky_wabbit,

I fully agree - the components in built up or kit JLH amps are garbage.  I had posted a link to bare boards available on AliExpress - the ones I received were of high quality.

The quality of the components one populates the boards with, along with power transformer, casework, etc. be up to the individual constructor's requirements and budget...

My personal experience with the JLHs is, as you say - they sound 'right', especially in the midrange, but they can't play very low, due to the capacitive coupled speaker outputs.

Did you also try the 1996 / 2003 circuit variants?  If so, what was your experence with them?

Regards,

Ross

hi Ross, I only built the original, but it has a 300VA transformer, huge PEH169 psu caps, fully regulated +_ rails, and roedersteib gold output caps. I've never noticed any issues with the bottom end, but then I usually run it with pretty efficient speakers. The idea of modifying it has never really appealed as I have been pretty happy with it as is.

This is a kit that you need to complete it with other parts, so of course you need a transformer. And what included is not the full heat sink , it is a heat transfer piece to a full size heat sink. These kits are decent , feel free to replace any component as you like.