I posted this up over on the Solid State forum, but I think its relevant here as well.
I found this site while rooting around. Fascinating site with a lot of history about the UK hi-fi industry over the last 30 years or so. I knew Stan Curtis was a prolific audio writer and designer, but I has no idea he was that involved on the business side as well, and responsible for some iconic products over the last few decades. A great read.
Stan Curtis, the hifi guru, introduction
🙂
I found this site while rooting around. Fascinating site with a lot of history about the UK hi-fi industry over the last 30 years or so. I knew Stan Curtis was a prolific audio writer and designer, but I has no idea he was that involved on the business side as well, and responsible for some iconic products over the last few decades. A great read.
Stan Curtis, the hifi guru, introduction
🙂
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Thanks Bonsai.
As you say, a good read. I remember the Stan Curtis CD players getting rave reviews at the time.
As you say, a good read. I remember the Stan Curtis CD players getting rave reviews at the time.
Yes, he is probably the UK's #1 audio guy in terms of experience in the industry. The story about the Cambridge amps is very good - I remember seeing the P30 (or was it P60) when I was about 18 and drolling over it - but out of my budget unfortunately.
I think Cambridge inaugurates the low profile style, its first amp came on the market prior the first Mark Levinson phono preamp, I think. They bear some ressemblance :
An externally hosted image should be here but it was not working when we last tested it.
It would be interesting to see the circuit details for these old timers if anyone has them.
I see mention of driving a squarewave into a 10mf ??? (uF 🙂) with no overshoot or ringing.
I see mention of driving a squarewave into a 10mf ??? (uF 🙂) with no overshoot or ringing.
I do have the schematics of the P40 - 20W amp and its preamp.
Quite unconventional, this last one. It used a cascade of three virtual ground stages. The first one having a 47 kOhm in series (just like some Linsley-Hood phono preamps) and a gain control pot to avoid any overload. The second one incorporates a mono-stereo switch and the third one deals with the RIAA equalisation.
The amp has a single rail -55V power supply with a single transistor input, a VAS load by a CCS which current of can be nulled by an electronic switch in case of output overcurrent. The output stage is made of darlingtons PNP (2*2N4289 in parallel for the driver, MJ491 for the power) and NPN (1*2N4286 for the driver, 2N5037 for the output).
If interested, I can scan them
Probably quite rounded rendition.
I think the 10mf is just annotation - it probably is 10uF. 10 000 mF is just about a dead short!
If you look around on his site, there are a few circuit diagrams.
If you look around on his site, there are a few circuit diagrams.
Thanks forr, its curiosity value really as its always interesting to see the topologies used.
It was the description of the "Clasic One" that intrigued me 🙂
Even 10uf would be pretty good going back then. I'll have another read through the site later.
hi all, where can one nowadays obtain dual log 47k pots c/w mains switch as per the p60 volume control/on-off switch. thanx.
You might have to cobble together bits from an old switch to add to the back of a modern vol pot.
But be wary of a metal control knob/stem going into a mains switch.
But be wary of a metal control knob/stem going into a mains switch.
CE safety regulations sensibly killed off this sort of power switching
edit - I wish this useful site got updated by Stan
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Oh I forgot to thank Paul for his website, took me a little time to place the familiar sounding name🙂 I have a P140X, I guess it is like P110, at that time there was 70x and 140x. Spec say 55W at 8 ohm, 36W at 15 ohm, 110 peak, IHFM 70W, max power (rms voltxrms ampere just befor clipping) 70W.
thanx. the switch has incinerated (heat generated by dirty/worn contacts) so i'll probably have to cobble something together. did think of a small box housing a soft-start but wanted to see if something close to an original was available.
If anyone is interested I have a Cambridge Audio P60 amplifier that is looking for a good home. It is the silver/grey version. I don't think it works although the power light comes on – I have no way of further testing it. It is in its original packaging, and was bought in Carlisle in 1974 at a price of £129. I have the manual and QA statement. Serial number is 600007. Location is nr Kettering in Northamptonshire.
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