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Old 23rd Jan 2019, 10:18 pm   #1
Lacan07
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Default WTD: Quad II Valve Amplifiers

Hi all

I'm on the look out for some Quad II valve amplifiers.

Original capacitors preferred and an unmolested transformer if possible. Not bothered about original resistors or looks.

PM me if you have either a single or a pair you'd be willing to sell.

Cheers

L
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Old 24th Jan 2019, 12:39 am   #2
GrimJosef
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Default Re: WTD: Quad II Valve Amplifiers

You're not the only one . There are quite a few on eBay.

It's rare for the transformers to be 'molested' but, assuming you actually want to run the amp, the original capacitors all have issues.

If the amp has been left unpowered for more than a couple of years then the smoothing block (C4 and C6) can fail if they're not reformed gently. Otherwise these are the most reliable capacitors in the amp.

The interstage coupling capacitors (C2 and C3) will either have become electrically leaky or will be at high risk of going that way. If/when they do then the KT66s can overheat and a great deal of expensive damage to them and to other components, including the transformers, can be the result. If the transformers fail slowly enough then the last thing they will do will be to ooze hot bitumen out of the amp and all over whatever it's standing on. Sticky, smelly and tough to remove.

The screen grid capacitor for the EF86s (C1) is a Hunts Mouldseal. The plastic body on these tends to crack, letting moisture in.

The KT66s' cathode electrolytic (C5) tends to dry out. If you're lucky it will fail effectively open circuit which will degrade the measured performance. If you're less lucky it will fail short-circuit and explode. Now the performance will be degraded and there will be a mess to clean up inside the amp. If you're really unlucky it will fail short circuit and not explode. Instead some component in the output stage (KT66s, output transformer, mains transformer) will be destroyed.

It's a brave man who leaves the original C2, C3 and C5 in situ.

Cheers,

GJ
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Old 24th Jan 2019, 9:55 am   #3
John Caswell
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Default Re: WTD: Quad II Valve Amplifiers

I agree with GJ,
I have two on the bench at present, all coupling capacitors (C2/3) were leaky, cathode bypass capacitor dried out, and Hunts Mouldseal C1 broken up.
Main elcos were fine, but as usual, a lot of the resistors were well outside tolerance as well.
All the original GEC KT66 had suffered and the man was lucky the OPTXs were still OK, so beware - look carefully
The Tonbridge Audiojumble is nigh, might be worth having a look there but be prepared to dig deep.

John
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Old 24th Jan 2019, 10:22 am   #4
Lacan07
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Default Re: WTD: Quad II Valve Amplifiers

Thanks for the heads up regarding capacitor issues guys.

I'll make a beeline for the Audiojumble next month (17th).

Is there still a steady supply appearing on eBay or have have numbers now dwindled? I know Quad knocked out quite a few units over the years.

L
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Old 24th Jan 2019, 11:50 am   #5
GrimJosef
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Default Re: WTD: Quad II Valve Amplifiers

Quad made almost exactly 80,000 of them (monos, so 40,000 pairs, if you like). A few were 'odd' (US mains transformers, 100V line output transformers) but unless you're looking for one of those they're not rare. If you're prepared to check eBay for a couple of months you'll likely see 10-20 pairs go past and find one that'll meet your needs. As John says though, these have been 'desirable' for at least the last 25 years and they tend to fetch what they're worth. The only bargains to be had are if you're very lucky at a car boot sale or a local auction.

Cheers,

GJ
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Old 25th Jan 2019, 9:31 am   #6
Lacan07
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Default Re: WTD: Quad II Valve Amplifiers

Thanks. I'll pop along to Audiojumble next month, are there usually a few units on sale? I was budgeting about 800 - 900 a pair.
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Old 25th Jan 2019, 3:34 pm   #7
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Default Re: WTD: Quad II Valve Amplifiers

Quote:
Originally Posted by Lacan07 View Post

Thanks. I'll pop along to Audiojumble next month, are there usually a few units on sale? I was budgeting about 800 - 900 a pair.
Hello,

In the late 2000's, I used to pick these up for less than 100 per unit if they were in poor condition but intact.

How things have changed! From what I can see, you may be lucky with your budget, but I've seen buyers ask for more than that for one of a pair with all valves missing and in need of complete restoration. I've tried to explain how absurd that is, but there seems to be a bit of a bubble in prices at the moment.

Good luck!
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Old 25th Jan 2019, 3:47 pm   #8
M0FYA Andy
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Default Re: WTD: Quad II Valve Amplifiers

Just what is it that is so special about the Quad II that makes folk willing to pay these prices? Certainly not rarity.
Other than the output transformer, is there anything other than bog-standard parts in it? Does nobody make replica output transformers to the old design?

Andy
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Old 25th Jan 2019, 4:50 pm   #9
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Default Re: WTD: Quad II Valve Amplifiers

Quote:
Just what is it that is so special about the Quad II
Probably the best amplifier of its day, good old plain engineering well executed. Almost anything modern of reasonable spec. will out perform them (who can tell the difference though unless measured). A piece of minimalist electronic art.
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Old 25th Jan 2019, 4:58 pm   #10
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Default Re: WTD: Quad II Valve Amplifiers

Hi, yes the transformers can be replicated or rewound, but a messy business as they are bitumen potted; make sure you don't forget the mystery component between 2 winding sections.

Ed
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Old 25th Jan 2019, 5:27 pm   #11
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Default Re: WTD: Quad II Valve Amplifiers

Leak, Quad and a bit later, Radford made some well-engineered amplifiers in their day.

There is nothing special about these, just good old engineering, carefully and thoroughly carried out.

What is special is that many people believe that good engineering can no-longer be done and consequently there is a bit of a feeding frenzy over period amplifiers.

You can either join in and have to pay the price, or you can walk away and find something good without a fan-club. If you're looking for raw material to do up for profitable resale, you're unlikely to find any bargains unless you trawl car boot sales and places where those unaware of the value of what they have might sell things. The reward versus time spent isn't going to make for a good hourly rate. But, If you're looking for a pair of Quad IIs because you want to use them, then they are often available and you're just stuck with the pumped-up prices.

I've had a few of the things on the bench. They are nice to work on, nicely built and sound OK, but I've never felt the urge to get a pair for myself.

Specialness is usually in the eye of the beholder.

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Old 25th Jan 2019, 5:27 pm   #12
M0FYA Andy
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Default Re: WTD: Quad II Valve Amplifiers

'Mystery component'?

How much would it cost to make an accurate transformer replica from scratch?

Andy
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Old 25th Jan 2019, 5:48 pm   #13
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Default Re: WTD: Quad II Valve Amplifiers

Further to Al's comment Lacan, it's probably hard to speculate about Quad II availability at Tonbridge. It is a "High End" event on the audio side but not everything [else] is very expensive by any means. I'm usually there at the later cheapo entry rate [ie 6] so many items will have already gone by then.

There has always been a "Professional Premium" to get in early but I see it's now on three levels. Either way and given your specific requirement, you'd be well advised to pay the 20 entrance at 8-30am but don't take that as any sort of guarantee

Dave W

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Old 25th Jan 2019, 6:08 pm   #14
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Default Re: WTD: Quad II Valve Amplifiers

Quote:
Originally Posted by dave walsh View Post
Further to Al's comment Lacan, it's probably hard to speculate about Quad II availability at Tonbridge. It is a "High End" event on the audio side but not everything [else] is very expensive by any means. I'm usually there at the later cheapo entry rate [ie 6] so many items will have already gone by then.

There has always been a "Professional Premium" to get in early but I see it's now on three levels. Either way and given your specific requirement, you'd be well advised to pay the 20 entrance at 8-30am but don't take that as any sort of guarantee

Dave W
I am sure there will be a few Quad11s there and as Dave says, at a premium but you pays your money etc.
I'll be there but as Dave says I won't be paying the 20 as for me at the moment its more of a social event to hook up with pals from all over the country. If you want a good deal though, then its worthwhile to get in early but it can be a bit of a feeding frenzy at times. It used to be that the really good stuff often got "Horse traded" by dealers etc before the event got properly under way. I've sold a few bits and bobs on a friends stall and most of the decent stuff had been flogged even as the event opened. I think the 20 charge gets you in more or less as the stallholders are unpacking still so it may give you a fighting chance of spotting a bargain.
Something I have noticed is how solid state stuff that you couldnt give away 5 years ago now fetches quite high prices although I'm sure I've seen the same Leak Stereo30 3 years on the bounce at a rather imaginative asking price.......................

A.
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Old 26th Jan 2019, 12:42 am   #15
John Caswell
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Default Re: WTD: Quad II Valve Amplifiers

Tonbridge Audiojumble now opens at 7:45 for table holders. I will be there together with "vinylspinner" on tables 38/39.
Premium entry is now at 8:30.
Come and introduce yourself.

John
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Old 26th Jan 2019, 7:54 am   #16
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Default Re: WTD: Quad II Valve Amplifiers

It's beginning to sound equivalent to an auction... the more you pay, the sooner you're let in, the more likely you are to find the more sought after items. So in place of the bidding war you have a fight to get in first and a Ryan Air-like early boarding fee.

I suppose the earliest entry price is self-capping at the cost of a small table.

David
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Old 26th Jan 2019, 12:20 pm   #17
Lacan07
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Default Re: WTD: Quad II Valve Amplifiers

Thanks all for the comments and advice, and apologies for the delay in responding!

I'd already seen the entry requirements on the Audiojumble website and planned to pay the 20 for early entry. Not sure I'm too keen on having to negotiate a 'feeding frenzy' though - I've had my fair share of run-ins with inconsiderate, elbow nudging collectors at vinyl fairs over the years which isn't really my style. Worth a shot though if I can't find anything in the meantime.

John Caswell, I'll certainly come over to say hi and look forward to meeting you and vinyl spinner at table 38/39.
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Old 26th Jan 2019, 1:07 pm   #18
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Default Re: WTD: Quad II Valve Amplifiers

Quote:
Originally Posted by bikerhifinut View Post
... It used to be that the really good stuff often got "Horse traded" by dealers etc before the event got properly under way. I've sold a few bits and bobs on a friends stall and most of the decent stuff had been flogged even as the event opened ...
I wouldn't say that all the decent stuff goes before the public are let in. But, as with every jumble sale I've ever been involved with, the very obvious bargains do. Cheap Quad IIs are perhaps the epitome of 'a very obvious bargain'.

If I were buying a pair of Quad IIs I'd want to know whatever the seller knew about their condition and I'd also want contact details just in case anything turned out to be iffy. A meter to check transformer and choke winding continuity (especially the mains transformer HT winding) and shorts to ground (especially in the choke) would be wise. Henry Dulat used to operate a valve testing service in the hall too, if I remember rightly.

Quote:
Originally Posted by Radio Wrangler View Post
... I suppose the earliest entry price is self-capping at the cost of a small table ...
The organisers strongly disapprove of that and do whatever they can to discourage it. Not only does it make it obvious to the regular punters that someone's got in before them, but it also leaves an empty space where the punters were expecting to see goods for sale. In busy years it can mean that genuine sellers get displaced to a less desirable stall position or, in extremis, don't even get a stall.

Cheers,

GJ
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Old 26th Jan 2019, 1:59 pm   #19
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Default Re: WTD: Quad II Valve Amplifiers

I doubt you'll be in a scrum Lacan. It's usually very friendly. The organisers themselves are very decent people but there is often only so much that can be done in the face of "human" nature and "the market". I've never had a problem with different "entry levels"-you don't have to pay the higher amounts after all, it probably mitigates any fevered behaviour and is perhaps fairer to those who do visit from Europe or Internationally! It's been explained previously that the extra ticket money also helps to maintain the "Jumble" as a bi-annual event that would be much missed if it ceased.

Dave

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Old 26th Jan 2019, 6:22 pm   #20
Lacan07
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Default Re: WTD: Quad II Valve Amplifiers

Quote:
Originally Posted by Radio Wrangler View Post
Leak, Quad and a bit later, Radford made some well-engineered amplifiers in their day.

There is nothing special about these, just good old engineering, carefully and thoroughly carried out.

What is special is that many people believe that good engineering can no-longer be done and consequently there is a bit of a feeding frenzy over period amplifiers.

You can either join in and have to pay the price, or you can walk away and find something good without a fan-club. If you're looking for raw material to do up for profitable resale, you're unlikely to find any bargains unless you trawl car boot sales and places where those unaware of the value of what they have might sell things. The reward versus time spent isn't going to make for a good hourly rate. But, If you're looking for a pair of Quad IIs because you want to use them, then they are often available and you're just stuck with the pumped-up prices.

I've had a few of the things on the bench. They are nice to work on, nicely built and sound OK, but I've never felt the urge to get a pair for myself.

Specialness is usually in the eye of the beholder.

DAvid
Thanks David

My plan for the Quads is to run a pair of speakers of similar vintage that were designed to be used with the classic KT66 valve. So just looking to recreate the period sound.
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