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The Quad thread


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  • 2 weeks later...

Those EAR amps are built to order and very rare. There are also some other direct drive amp from Germany but I forget what it was called. Also some from Holland too...

The Quads like good, clean power. Class A monsters will work well give how immune they are to the load. It's not a good idea though to use an old ESL57 with a 25w+ amp if they aren't fitted with the clamp boards (which work in a similar fashion to the zener's Stax used on the transformer boxes). Old school Krell did sound very nice on some ESL63's and even a rebuilt 303 did a good job with ESL57's.

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  • 1 month later...
Guest sawyers

Talking of ESL57's, I've just bought a pair. Serial numbers 13702 and 13706, so 1964 vintage. Stickers say serviced by Quad in '82, and they certainly replaced the HT multiplier at that time (date stamp 1980). They have taken for ever to charge up - 9 hours on and they are still increasing in sensitivity and sheer beauty.

I've wanted a pair of these since I was 16, when these particular speakers were 8 years old. Better than the ESL63's in certain areas.

Feeding them from an Audio Research D125, capable of chucking out 100W plus from doubled up pairs of 6550's, so I definitely need to fit a clamp board before I toast the tweeter panel.

Craig

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Feeding them from an Audio Research D125, capable of chucking out 100W plus from doubled up pairs of 6550's, so I definitely need to fit a clamp board before I toast the tweeter panel.

Now that is an interesting amp. It's not as revered by the AR faithful as other models because of its hybrid nature. In my eyes that is an advantage as the D125 brings a bit less on the used market than some of its all-tube brethren. Is yours outfitted with cooling fans? If so, how noisy is it?

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Guest sawyers
Now that is an interesting amp. It's not as revered by the AR faithful as other models because of its hybrid nature. In my eyes that is an advantage as the D125 brings a bit less on the used market than some of its all-tube brethren. Is yours outfitted with cooling fans? If so, how noisy is it?

I bought it maybe three years ago to replace an older fan cooled Krell KSA100. Cost

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Guest sawyers

Well, the ESL57's needed a bit of TLC. Eventually it became evident that one speaker was quieter than the other, and with the treble down even further.

Off with the back and the front, and a burn mark in the tweeter panel was evident. Fortunately I live about 50 miles from One Thing Audio (Coventry UK), who specialise in the '57 and '63. They'll rebuild panels, and have even designed their own tweeter panel based on modern materials that is more robust mechanically than the original.

Quick phone call, and off I went.

So I came away with an original but measured OK panel for

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Guest sawyers

I'll take some pics of the 57's tomorrow and put them up. Should've taken some pics with them in bits - but hey, I was just following dismemberment instructions off the web, so nothing revealed that you can't find out there.

They are wonderfully primitive, which I guess reveals their mid 50's heritage - but I'm in audio nirvana. Now they are back together and working right they are quite astonishing. Vocals in particular are mind blowing, but they show ever wart in a recording - which means that with most non-live recordings you can clearly hear the lack of musical integration where things are multitracked, close miked, or the recording engineer has put a heavy fist on the EQ and FX. But given superb material (Mercury Living Presence recording of the 1812 for example) it really is like being at a live performance.

These have to be a lifetime bargain - total cost of buying the things including all the bits to rebuild the "crossover", protection boards, new wiring and a tweeter panel was

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Guest sawyers

I've uploaded a couple of pics of the ESL57's to the albums bit of the forum. They as you can see are sited on coffee tables at the moment while I make some bespoke stands for them.

One thing I found is that the treble units come in two flavours - pre 1988 and post 1988 - which do not give the same response. Quad changed the stator design because of availability of the older type.

Anyway, as you know, I changed one panel because of a burn mark - that was older vintage. In rebuilding the other one, I discoverd a small burn mark and took it up to One Thing Audio today. Ah - that is a new style panel - we'll replace it with an older one so that they match, they said. when Quad serviced them they must have replaced the treble panel in only one of them, so producing an unmatched pair.

So there is some subtlety to these beasts.

You might notice that the end cheeks have been changed - they were stained a faded and rather bilious orange. So I stripped them and sanded back to the underlying beech, and then gave it a coat of wiping oil (Danish oil). They look much nicer than a darker stain IMO.

Craig

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Guest sawyers
Do I see a VHS player in there?

I have to own up. It gets used hardly ever, to the extent that it isn't even plugged in. But we've got a ton of VHS tapes, which look really miserable as compared with a DVD.

But you'll notice in the background Stax lambda, DT990 and AKG K701 headphones.

Craig

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  • 2 weeks later...

Great news! I finally got off my lazy ass and shipped the speaker to Kent, whose turnaround was very fast. I'll just copy and paste his email for those interested in what was wrong with the speaker:

I received your speaker last week. Nothing terribly wrong with the

speaker but it had quite a few assembly problems which were the source of

the noise.

I found several cotton balls placed inside the elements. This created

quite a bit of contamination in the panels. I have taken apart and

cleaned each element of the cotton fibers.

The delay lines had been cut to do previous repairs. They have been so

damaged that they need to be replaced.

Internal damping foam has rotted. This is typical for Quads of this age.

The dust cover assemblies have been rebuilt but not very well.

The safety grounds have been removed at some point. The ground paths keep

the safety screens at ground potential in case there are any accidents and

the safety grounds should be replaced.

Here is the break down for repair:

1 - Rewire delay line assembly $75

1 - Refoam Frame/Plinth Components $50

2 - Rebuild Dust Cover Assemblies $100

1 - Asssemble and Test $50

1 - Round-trip freight $130

TOTAL $405

At some point the EHT power supply board has been replaced with a Quad

produced board. I imagine the other speaker has had the board replaced as

well. The EHT board/supply work correctly but these replacement boards

produced by Quad have the EHT bias voltage set at maximum. This is a much

higher bias voltage than was originally delivered with the speakers.

Quad raised the bias voltages over the years so the speakers would play

'louder', i.e. more sensitivity. Early production speakers were about

10-15% lower in bias voltage. Raising the voltage does make the speaker

play louder but at the price of decreased element life. I do not think

this is a good performance trade off and routinely set bias voltage at the

original factory spec.

I perform this change on all Quads in my shop at no charge and would like

to lower the bias voltage on your speaker as well. This will present a

problem in that your existing speaker will play a bit louder than this

speaker. You would need to adjust your preamp balance control to make up

the difference.

I keep records on each speaker I service, i.e. bias voltage levels,

sensitivity, etc. If the other speaker is sent in for service at some

point I can make the same bias voltage adjustment so you would have a

matched pair again.

Or I can send the necessary resistor and instructions for lowering the

voltage on your speaker if you can do the work or know someone that can.

It is easy just replacing a single resistor.

Lowering the bias voltage and turning off the speakers when not in use

will yield the longest panel life. And they should be used in a dry

environment, i.e. humidity levels no higher than 50%.

I decided to go with lowering the bias voltage. I'll just use the balance controls if I can't replace the resistor in the other speaker myself. Since the other speaker is stock I'm sure it will eventually start making noise and make its way to Kent eventually.

anyway I'm pretty psyched to have the working speakers back soon.

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