I've just posted the articles on a separate thread 'JLH 30 watt amplifier articles'
It was a lucky find, and included a JLH tuner and cassette deck too. The tuner seems fine (I haven't yet tested it with a good aerial) and I tidied up the display with a clear perspex screen. The cassette deck may not be finished (although there was a cassette in it) and I think I will probably pass them both on as I won't use the tuner and already have a cassette deck for archiving.
It was a lucky find, and included a JLH tuner and cassette deck too. The tuner seems fine (I haven't yet tested it with a good aerial) and I tidied up the display with a clear perspex screen. The cassette deck may not be finished (although there was a cassette in it) and I think I will probably pass them both on as I won't use the tuner and already have a cassette deck for archiving.
That’s a gorgeous amp! Very pretty, outside and inside too.
But I think funkuncut is right in wishing to preserve construction with minimal messy changes.
Best,
Steve
Just wanted to affirm your comments—- good observations. It would be interesting to know how much attenuation the volume control is introducing when positioned for a typical loud listening session.
But I think funkuncut is right in wishing to preserve construction with minimal messy changes.
Best,
Steve
Some years ago , I've found schematic , related to speaker impedance, kinda like negative output impedance for amplfier ,or current mode, can't remember now. There was a low (0,22 maybe) ohms shunt , some resistors , capacitors ,and fast opamp.Kinda of bridge ,combining positive and negative feedbacks. That was article ,published in one of popular radio magazine. Circuit's output was connected to amplifier input , so volume control must be no longer connected to amplifier itself.
So identically like in this amplifier, all opamp noise was audible always , independent of volume control position. I have heard a hiss , white noise , clearly ,and not only in silence. And offcourse i was disappointed and undone changes. Imagine , if that circuit would oscillate, you can easily blow speakers, and volume control won't help . In my opinion, silence must be present when you listen not loud . Hiss is thing from tape times. But everything is choice of user ,modify, improve something, or keep it conservated like just purchased and still in warranty.
So identically like in this amplifier, all opamp noise was audible always , independent of volume control position. I have heard a hiss , white noise , clearly ,and not only in silence. And offcourse i was disappointed and undone changes. Imagine , if that circuit would oscillate, you can easily blow speakers, and volume control won't help . In my opinion, silence must be present when you listen not loud . Hiss is thing from tape times. But everything is choice of user ,modify, improve something, or keep it conservated like just purchased and still in warranty.
I recall building the cassette deck cheaply (well I worked at PYE TV then... ), great sound, modded it to adjustable bias with a built in oscillator for calibration, and with coloured single LED vu meters, but the cassette mechanism was a bit clunky. Gave it away! Back in the day we were blessed with DIY design and construction availability.
I hope this isn't getting too far off topic. I'm going to listen to the amp a lot more before doing anything else to it - I think it wasn't designed for the level of input from cd, so it's actually quieter with MM input. I've tried it with a Shure M75 and a Goldring G800 (which always seems to have low output anyway) so far and it sounds really good, just not as pokey as with cd, but that is to be expected. The important thing is that it is now quiet (and I'm using it for reggae, jazz and rock anyhow...)
Here you go....
I'm happy to post you the paper copies if you pm me your address, and if you (or anyone else for that matter) would like the series 2 cassette deck, you're welcome to collect it from London or I can send it for postage cost. I haven't had it working, and I don't need another project at the moment, but it would be great to have it used and preserved.
I'm happy to post you the paper copies if you pm me your address, and if you (or anyone else for that matter) would like the series 2 cassette deck, you're welcome to collect it from London or I can send it for postage cost. I haven't had it working, and I don't need another project at the moment, but it would be great to have it used and preserved.
I built one of the casette decks some (many) years back and it was decent. Great electronics let down by an average mechanism and lack of Dolby or other noise reduction.
Tape head alignment was crucial and all the mechanisms needed it before you got the best from them. Also, the motor often needed to be turned on the mount to minimize noise pickup through the tape head.
Those things aside, the Hart kit was quality, easy to assemble and worth the not inconsiderable cost at the time.
Tape head alignment was crucial and all the mechanisms needed it before you got the best from them. Also, the motor often needed to be turned on the mount to minimize noise pickup through the tape head.
Those things aside, the Hart kit was quality, easy to assemble and worth the not inconsiderable cost at the time.
Certainly the amp, tuner and series 2 cassette I have all seem to be high quality electronics - the hardware such as faceplates, knobs etc. has a slightly British made-by-men-in-brown-coats-in-a-draughty-shed feel as opposed to Japanese made-by-robots-in-a-shiny-laboratory feel, but that is part of the charm too.