Linsley Hood SE 10W amp

[Asen]

Has anyone made the JLH 10W amp? I'm in a process of building it right now. Any other's experience is wellcome.
I'm interested in the PSU you use. That's what I haven't finished yet.

[Edited by Asen on 01-17-2001 at 05:48 AM]

[FYC]

I think JLH is not a fans for Single End? His design are more on push-pull?

[Asen]

His first SE design was made in 1968. According to his words it works fine compared to a Williamson tube amp.

[tim0]

Hi Asen,
i built JLH's 1968 design about a year ago. It worked very well with my speakers, at that time 99dB/W direct radiators.
i used a 460VA toroid as the power supply with ordinary bridge rectification and about 100000uF (0.1F).
There are some photos etc on my website.

These days the chassis houses an Aleph 3 variant.
Regards

BTW, shouldn't this thread be in the SolidState forum?

[Asen]

Of course it should. My mistake. Sorry.

[Jon T.]

I've run some simulations of it trying to decide if I want to build it or not. Instead of the original, I would get a copy of the update he did to it in 1996, it has more power (15W), better current control, and uses parts that are available today.

I've run some sims with much better, modern parts (MJL1302 outpus, BC559 inputs, etc) and it definitely benefits from the upgrade. It also does 25W before clipping with these parts.

Mind you, this is all simulated, so YMMV...

-Jon

[Nisbeth]

Hi Asen

I've looked at the JLH 15w myself, but I have to many projects going on right now, so i'm not reallly getting any further. If you like, you can get more info about the updated version by following this link:

http://holly.colostate.edu/cgi-bin/cgiwrap/smassey/hood

BTW, I think Jon is right, getting audio-grade parts for the design is worth the extra cost - it is a very promising design with lots of potential.

/Uffe

[Geoff]

The URL in the last posting is out of date. The correct one is: http://www.geocities.com/shakeytheworm/hood/hood.html

There are several other sites on the Web with write-ups on this amp. If anyone wants the URLs, let me know.

To the previous correspondents, stop simulating and get building (preferably the 1996 version), you won't be disappointed!

If anyone wants advice about this amp then contact me. It is my pet project so I know it well.

[rmgvs]

I've build the 10 Watter a few years ago and find that this amplifier still is among the best (despite the capacitor at the output).

Then I heard the Hart-kit from a friend of mine. This kit takes the later symmetrical Linsley-Hood amplifier as a basis. I found the results inferior on all counts via-a-vis my old amplifier. Okay, I used a really big power supply and first class components..

Still I wondered how to get rid of the capacitor. I then used the original 1969 circuit and modified it for a symmetrical power supply. Only a few changes have to be made (I have the schematics in gif format but don't know how to display that on this page).

Now some strange things happened. Firstly: when the amplifier is turned on, there is a large temporary DC-offset voltage at the output (10-15 Volts). After 10 seconds it fades away to zero Volts. Secondly: there is a big very big hum (while the original schematics with the same components is dead quite). I can only get rid of the ripple by using a big power resistor (3-4 ohms, 15 Watts) in the power rails (plus and minus rails). I want to avoid regulated supplies because I think the less electronic stuff the better. But okay, it works.

Some friends of mine have had the same experience and not solved the problem till this day. Anybody suggestions?

By the way: the sound of the 'old-plus' version is great!

Rudy

[argo]

I'm in.
I want to try out that amp.
You mentioned that there are also more URLs - please pass them on.
Any other input and driver transistor substitutions would be also interesting to know . What about BC556 and BD139/140?

Argo