Quad ESL63

[Mark Hennessy]

I honestly don't know if I upset Ted or not. For all I know, he simply might have not revisited the thread to see what I added. No matter. I've been working with BBC operators for long enough - and of course, I've worked with some of the people that trained them. However, there are some operators who have a good engineering background - Ted included, of course. And there's no reason why an electronics engineer can't produce a good mix or drive a TV or radio programme - if I say so myself, perhaps slightly immodestly. Of course, as well as doing, I also train people to do these roles. So honestly, I think I come at it from all angles. Plus a bit more, given my experience of the hifi and pro audio industries.

It's definitely true to say that measurements alone will not produce a good loudspeaker. Even with all the modern tech available today, there's still a fair bit of art involved - despite what most engineers outside of the subject might believe. Never mind the designing - just measuring loudspeakers is one of the most complex areas of audio engineering that I know about, and I don't claim much, if any expertise (definitely a case of "the more I learn, the less I understand" if I'm being brutally honest!). But all that said, some basic measurements ought to be the starting point when compiling a shortlist. The BBC always used to combine measurements with subjective testing in the good old days, but now the pendulum has swung completely towards subjectivity, and I'm not aware of any loudspeaker selection exercises in my time in the job that involved measurements - and that explains why we have a number of speakers in service that are all over the place. Worse, some selection exercises weren't even blind, so you end up having to throw away complete sets of results when someone has given 5 out of 5 for all categories for their preferred brand, and 1 out of 5 for all the others (yes, that has happened, and I think it's absolutely astonishing that the person(s) doing that could have thought that their results would be taken seriously!).

While of course I'm happy to chat privately - and am just emerging from a very busy period, so now is a good window for once - I'm honestly not sure what I can add. I'm not going to give specific recommendations for all the reasons I've already explained - to do so would be doing you a disservice. All I can say is that if you like the ESL sound, then definitely investigate monitor-style speakers from brands like ATC, Graham Audio and Stirling Broadcast (in alphabetical order, and these are just the first 3 that come to mind). If you can arrange a home dem lasting a few days, so much the better - but I know that is very difficult indeed. If you can wait until better times, I do have more speakers here than I care to mention (and can borrow more from work), so you'd be welcome to spend a day playing around. I can arrange blind AB testing, etc...

[ppppenguin]

Years ago when spent my gap year (1974-5) at BBC Research Dept (Kingswood Warren) I was doing TV stuff but was aware of audio work. It was in the days of Harwood. I went into the anechoic chamber once which is a strange and unsettling experience. Apparently they tried to get musicians to perform in there which was well nigh impossible. They were also making scale models of studios with the aim of testing the acoustics in the days before computer simulations were feasible. I'm sure the relevant reports are on the BBC R&D website.

I know that acoustic measuements are fraught. Not least because the room plays a major part. I'm sure there's an art to designing speakers that will work well in a wide range of non-optimal roms. As against working superbly but only in very tightly controlled spaces.

I know that Quad claimed that the ESL63 can produce a decent 1kHz square wave, as measured by a precision microphone. That's a pretty astonishing achievement - I wonder how many other speakers can approach this. Or how important it is in terms of perceived quality of sound.

I know that Audio Gold will do home demos. Need to check what monitor speakers they sell. There are several other audio dealers fairly close to me, both domestic and professional. AG are basically domestic, others such as Funky Junk are professional. If anyone tries to sell me cryogenically treated speaker cable or other such snake oil then I'm likely to walk out.

Thanks for all the trouble you've taken and the invitation.

In the recent past I've been involved in stripping out a couple of TV facilities. Unfortuantely there were no main monitors to be had. Not even any of the bigger nearfield monitors. All I got was a couple of pairs of Mackie CR4: https://www.amazon.co.uk/Mackie-CR4-Crea...B00KVEIY4O which I haven't yet tried. They look great for doing video editing (which was their role before they came to me) but far from ideal as domestic hifi. A pair may replace the 20+ year old Altec Lansing speakers I use with my main PC.

[peter scott]

Years ago when spent my gap year (1974-5) at BBC Research Dept (Kingswood Warren) I was doing TV stuff but was aware of audio work. It was in the days of Harwood. I went into the anechoic chamber once which is a strange and unsettling experience. Apparently they tried to get musicians to perform in there which was well nigh impossible. They were also making scale models of studios with the aim of testing the acoustics in the days before computer simulations were feasible. I'm sure the relevant reports are on the BBC R&D website.

We had one at HP too. Not for audio purposes but for EMC but the great big foam pyramids we equally effective at audio. It certainly was a disorienting place to work in but still nicer than the alternative of the open test site on the roof, leastwise in the winter when HP provided two anoraks one for you and another to protect the spectrum analyser from the rain and snow although we did eventually get a small hut at each end of the site.

Happy days!

Peter

[ppppenguin]

The service planning guys at Kingswood Warren reckoned to do the field work (both around the country and on the outdoor antenna range) in summer and number crunching in winter. There are hairy stories about driving round narrow lanes in a VW Microbus with pneumatic mast extended. I'm sure that was against the rules; a lovebus is none too stable without a mast on top.

[ppppenguin]

In another thread I said I'd been given a pair of Alesis M1 Active Mk II speakers: https://www.alesis.com/products/view/m1active-mkii
I've been using them for a while and think I like them. They may not be the finest speakers on the planet but they seem to be doing a lot of things right and not too many wrong.

If I decide to keep them I'll need to solve two problems.

First is mounting. I think the best solution in our lounge will be wall mounts such as these: https://www.richersounds.com/btech-speak...-pair.html

Second is how to drive them. They need a professional line level input, though they have pots on the back to cover quite a wide range of levels. My Quad 33 pre-amp doesn't have enough output to drive them sensibly. Not susprised. I have a Quad 34 that belonged to Ruth's late partner. I'll see if this has a high output option but again I rather doubt it.

At the moment I'm running them from the 405 with 1K and 150R attenuators which works well. Does seem a bit daft to use a 405 to provide a bit of line level gain. Unless anyone has any better ideas I think the answer will be a box with a NE5532 in it. It's not a demanding role. How to power it? I may have an odd +/12V brick somewhere, or a small transformer with 7815/7915 regulators. Whole thing in a diecast box hidden away. I know I could use a single supply rail and coupling caps but my background in design for professional kit always makes me think of split rails. It might well end up DC coupled unless I can think of a good reason to do otherwise. Could even do a crude balanced output with another couple of opamps, effectively one NE5532 each for left and right.

As an aside, I sometimes wonder why the 'phools haven't latched(!) on to balanced audio and XLR connectors. Perhaps the problem is that they just work, even come hell, high water and pestilence. No magic.

PS: The Mackie CR4 speakers are now doing great service with my main PC.

[Nick]

At the risk of plugging my own site, I did a Quad 405-2 rebuild and wrote it up (more of a stream of consciousness really) at https://nick.desmith.net/Electronics/QUAD_upgrades.html

Main things were just sorting it out a bit and making the gain suit more modern pre-amps. There's a few things I'd do a bit differently now, but I still really like the amp.

I also happen to have a pair of ESL63s in the loft - they used to belong to Sir Clive Sinclair and are in dreadful shape (cat savaged cloth, coffee stains, tobacco stains...) ... another project in the pipeline...

   

Some of the other Quad projects in the queue...

   

[chriswood]

Jeffrey
If you want to make use of the Quad 34 there is an official mod to change the output for other power amps or speakers with amps built in.
The out put of the 34 has a potential divider to drop the output to 0.5V,  by changing R118/121 to 1K and R119/122 to 2.2K you will get around 1.1V which should suit most modern units.
The downside is if the 34 has been sitting around for a long time it may need a bit of an overhaul.
Chris

[ppppenguin]

Chris, thanks for the guidance on the 34. Apart from the usual electrolytics, is there anything else that needs attention on a 34?

PS: I've just looked at the 34 circuit for the first time ever and indeed the output is attenuated by a factor of about 3 by resistors.

One other little problem is that the permanent cabling from the amp to the speakers is some old 7/0.029 T&E run under the floor to some outlet plates. Fine for LS level, possibly not so good for line level driven from medium impedance. the only way to find out is to try it. That's why I was thinking of low impedance drive, possibly balanced.

[chriswood]

The 34 will need electrolytic caps, and there are a lot of people that think you need to upgrade the op amps and other parts but I think that is optional, I take the view that most of the music you listen to has gone through jelly bean op amps in mixer desks so why worry about the TL071s in your preamp.
The Dada site has useful information on the 34 here https://www.vintageshifi.com/repertoire-pdf/Quad.php about half way down.
With the cabling I would just try it, if it doesn't work could it be used to pull new cabling through?

[ppppenguin]

I'm not worried about TL07x opamps either. Doing electrolytics is routine.

All I can do with the cables is suck it and see. Pulling through new cables would be difficult. Too many odd corners.