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Simon Whiting Simon Whiting is offline
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Default QUAD I amplifiers

Hi all,
I don't know much about valve amplifiers, and I hope that your members might be able with some advice.
I've got a couple of QUAD I* amplifiers, but one of the output transformers has been changed** at some point. (It's easy to see because mine haven't got any boxes over the transformers, unlike some pictures I've seen on the web. There's no sign that there were any fitted, and I presume it's because they're earlier models than those pictured - serial numbers 195 and 821.)
However I have got the old (non-working) output transformer. So my question is, would it be worth - or even possible - getting it rewound? In all honesty, I can't really tell any difference in the sound between the two amplifiers. There's a bit of crackling now and again, but I presume that that's just down to the somewhat ancient and brittle wiring and joints. (Not much has been replaced.)
If it is worth rewinding, does anyone know where I could get it done, preferably in the UK? Or would it cost a small fortune?

Simon.

*They don't actually say "QUAD I" on them, just "QUAD", but I think they weren't really called QUAD Is until the IIs came out.

**EDIT: That is, changed for a non-QUAD transformer - different shape.

Last edited by Simon Whiting : February 24th 13 at 08:04 PM
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patrick-turner patrick-turner is offline
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Default QUAD I amplifiers

On Monday, 25 February 2013 01:14:20 UTC+11, Simon Whiting wrote:
Hi all, I don't know much about valve amplifiers, and I hope that your members might be able with some advice. I've got a couple of QUAD I* amplifiers, but one of the output transformers has been changed at some point. (It's easy to see because mine haven't got any boxes over the transformers, unlike some pictures I've seen on the web. There's no sign that there were any fitted, and I presume it's because they're earlier models than those pictured - serial numbers 195 and 821.) However I have got the old (non-working) output transformer. So my question is, would it be worth - or even possible - getting it rewound? In all honesty, I can't really tell any difference in the sound between the two amplifiers. There's a bit of crackling now and again, but I presume that that's just down to the somewhat ancient and brittle wiring and joints. (Not much has been replaced.)


Gee, crackling now and then. I have never ever found any tube amps or radios etc made in 1950s to ever be free of faults, some real big ones. And yet, with faults, they manage to make maybe 2Watts even though one doesn't notice the THD at 10 times the 0.03% it should be. One really needs to be highly skilled to know what to look for, but hey, after you re-build about 10 amps to a very high standard you then learn fast, and its all so much easier than having to restore the electronics on say, the Apollo moon lander, now getting old.

If it is worth rewinding, does anyone know where I could get it done, preferably in the UK? Or would it cost a small fortune? Simon. *They don't actually say "QUAD I" on them, just "QUAD", but I think they weren't really called QUAD Is until the IIs came out. -- Simon Whiting

There's a good Quad site at http://www.keith-snook.info/schematics.html

Keith is such a nice man.

But he's just a little shy to ever want the world to be as complex as it is, or could be, even if it means betterment for all, and methinks he don't much like the info I have at my website about modifying Quads in manners akin to putting a decent engine, brakes, steering, supension, et all, into a 1960 Morris Minor, painted iridescent metallic purple. Let us forgive Keith, the perfectionist.

:-)

He does say at his website to never try to use the Quad "Concordant" circuit where you see the BBC type of circuit for Quad II where the first pentode input is in triode mode, and second tube socket where there was once a second EF86 has a 12AX7 LTP instead, all of which, to my silly old mind, makes sense, and IS better, although almost anything anyone does to any Quad tube amp is an improvement and a getting away from the mentality of bean counting a la' 1955 "Bwitish Industrial Cost Saving" style, at which Mr Walker was so good at.
(( Yet the Mr Walker was justfiably brillaint, famous, and wonderful for his work with ESL speakers. )) The Concordant schematic has a note above about the dissimilar anode loads for 12AX7 halves in LTP. But the unequal loads are there so Vout are correctly balanced, it ain't a misprint.
But Keith's info on the Quad-II OPTs was SUPERLATIVE, and I much benefitted from reading his site, because nobody bothers to really examine hidden things not obvious to others. Now, he may/may not know about Quad-I, but there'd be no problem if you emailed him about it, and if he knew someone else, he'd be likely to tell you.
I know I ain't at all perfect, and Keith and many others can't be expected to know everything either, and the more ppl you talk to the more likely you'd be helped.
Patrick Turner.

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