ESL57 bass panel from scratch

[Fabien Lefebvre]

After re-building ESL 57 panels, next step: build a bass panel from scratch.

For this I need some information:what is the exact drill size for the 3*1183 holes in the stator (active zone) ?
I measured something slightly above 3mm. The problem is that it might be an imperial size.

Drill size Diameter (in) Diameter (mm)
...
3 mm 0.1181 3.0000
#31 0.1200 3.0480
3.1 mm 0.1221 3.1000
1/8 in 0.1250 3.1750
3.2 mm 0.1260 3.2000
...
(source: Drill Size Chart - Machining)

Even some guess might help: maybe Quad had some habits wrt which unit to use when designing its products.

[chinsettawong]

Hi,

Sorry that I don't know anything about the hole size you ask, but I am very interested in your project. What material do you plan to use for the bass panel? Can you share with us the dimensions?

Wachara C.

[Fabien Lefebvre]

Originally Posted by chinsettawong

Hi,

Sorry that I don't know anything about the hole size you ask, but I am very interested in your project. What material do you plan to use for the bass panel? Can you share with us the dimensions?

Wachara C.

My intention - provided I go up to completion of this project (*) - is to build something close to original.
Thus dimensions are simply those of an original panel. Just open one and you will get all needed information. For example they are made of 2mm plastic, same for spacers, ...

(*) I am not convinced that there is need for such project: bass panels can always be re-built. Thus just for fun ?

[chinsettawong]

Hi Fabien Lefebvre,

Unfortunately, I don't own a set of of Quad 57.

If you do own a set, of course, it would be wise to just rebuild it. But it would be a fun project to clone it.

Wachara C.

[Fabien Lefebvre]

Without the ESL, it will indeed be more difficult.
For a start, here are overall dimensions: 325*647mm.

[Fabien Lefebvre]

I tried to measure precisely.
I get something above 3.1mm maybe 3.15mm.
My candidates are therefore 3.1mm and 1/8inch.

[oshifis]

Fabien,

Does it really matter? I mean I ordered a pair of replacement middle/tweeter panels from Quad itself (some 20+ years ago) and the replacements were sligthly different both physically and in measured frequency response. There is a chance that a little deviation makes the result better (or worse) than the original.

[Fabien Lefebvre]

Originally Posted by oshifis

Fabien,

Does it really matter? I mean I ordered a pair of replacement middle/tweeter panels from Quad itself (some 20+ years ago) and the replacements were sligthly different both physically and in measured frequency response. There is a chance that a little deviation makes the result better (or worse) than the original.

Well I think that the hole size in the active zone is the only dimension that really matters. Yet this is indeed a minor issue.
Has someone some kind of PVC to suggest to make these stators ?

[owenhamburg]

I have only disassembled a Quad ESL 57 tweeter, and its in a different country from me right now. From memory the panels looked like a thermo plastic, and its manufacture looked very simple and possible in a workshop.

To clone Quad ESL 57 tweeter (I would buy one if not doing it as an exercise in manufacture or basis of my designs) I might take a molding of the inside and use that as the former for simple heating with a molding jig (though I would be tempted to design my own, similar solution), if Quad also used heat molding of sheets approach, with 1/8inch plastic sheet, the thickness in some areas of the plastic would be less. I should not expect the thickness of the plastic is that critical, but the hole depth might be.

For simplicity and with a pillar drill I would drill before molding, with the right temperature the holes should remain through molding, as the plastic becomes like heated cheese, in this consistency the jig should be apply force to the stators around the molding similar to vacuum packing.

The aluminium foil coating could also go on before as the heating may help bond the foil layer, and make manipulation easier, and probably wont hurt it, and cleaning the hole edges might also be simpler while it is a flat sheet of thermo plastic.

Then I would put the plastic in an old oven strapped into a simple jig to corrugate the sheet in the way I assume Quad did. It would be an interesting project.

I think the real genius in Quad is their manufacturing products of high consistency with out the need for highly skilled manufacturers. Is Polypropylene a good candidate electrically or just good for the heat forming manufacture?

I cant help noticing this from wikipedia;

History

Propylene was first polymerized to a crystalline isotactic polymer by Giulio Natta and his coworkers in March 1954.[3] This pioneering discovery led to large-scale commercial production of isotactic polypropylene from 1957 onwards.[4] Syndiotactic polypropylene was also first synthesized by Giulio Natta and his coworkers.

Is this just a coincidence ?

[cfb]

This info was posted quite a while back over on audioasylum but since it has probably been archived and forgotten.

The original stator material that Quad used in the ESL 57 was a rigid unplasticised PVC sheet, also known as uPVC, brand name “Darvic” this information came straight from Mr. Robert Flain of Quad.

Polypropylene is too soft a plastic to use to maintain its shape after perforation. The holes were hot press punched by the way and for the hobbyist the best alternative would be to set up a jig and drill a stack of PVC sheets but that many holes will be tedious. Unless you happen to have access to a machine shop or plastics company that would press punch the PVC for you but then the minimum order and setup fees would exceed the price of a used set of Quad esls.

The consistency of thickness of the stator will affect the performance of the panel and is a critical parameter of the manufacture of the esl if one is attempting to replicate the original Quad esl panel as closely as possible. A few years back there were some audio engineering papers published which discussed mechanical inconsistencies (thickness, distance gap, warping etc.) in stators as being a major cause of distortion in electrostatic speaker systems; but I cannot recall at the moment the exact reference, someone else can probably cite the source.

Hope this is of some help.

One source of pre-perforated PVC sheet is San Diego Plastics at, Perforated PVC sheet

As for any other considerations; the jig and weight setup you use to tension the mylar should be given considerable time and attention to insure consistency, and be sure to use the “Calaton CB” soluble Nylon suspension for coating the mylar or at least the DuPont Elvamide nylon resin.