Quad ESL57 clamp board?

[neskor]

Anybody tried to change clamp board with Gas Discharge Surge Protector as Sheldon suggest?
Is there any truth that clamp board affect the sound of the speaker?

 

[AVWERK]

When you consider you won't torch a panel with it, your perception with it in changes to the positive.
I originally thought there was a slightly negative difference , but as time passes, either time breaks it in or you get used to whatever you thought might be an issue to now there's no way I would take it out.
Save your panels and enjoy the music!

Regards
David

 

[arend-jan]

I don't trust the gas discharge to do it's job properly. They have bad controlled spark voltage and limited spark lifetime.

Get a proper clamp board and NO it won't impact the sound. Anyone who claims otherwise is welcome to come over for a blind listening test

 

[ejp]

Sheldon has stopped recommending this. On the face of it, it's plausible, and shouldn't have any effect on the speaker until it fires, but when the gas discharge triggers it presents a short-circuit back to the amplifier, which won't be good for it, as opposed to the zener diode chain which merely clamps the output to effectively 17V peak in the primary, which is not nearly as bad for the amplifier.

If anybody wants to try it (at their own risk) I have a small supply of the correct component.

 

[stokessd]

Anybody tried to change clamp board with Gas Discharge Surge Protector as Sheldon suggest?
Is there any truth that clamp board affect the sound of the speaker?

You are correct, I no longer put them in customer's speakers.

In my experience, the gas discharge tubes can get leaky or worn out over time. Fortunately they clamp lower rather than higher over time so your panel is protected. This has only happened to a couple of customers, but one is too many.

The other issue is that the tube clamps at different voltages based on slew rate (and to a lesser extent, the history of the signal). So you have to "size" the clamp voltage to accommodate the worst possible case. That means that it is limiting the max SPL to some degree.

In my experience, if there is a sonic penalty to the clamp board it's really subtle to non-existant, and the benefit is real and significant. so everybody should use one.


For everybody's benefit, I have drawn up my clamp board design and put it on OSH Park.

Here's a blog post on my board with schematic and pics:
Sheldon’s World >> Blog Archive >> Original Quad ESL Treble Protection Boards


And here's a link to the boards for you to buy:
OSH Park ~

The best part is the blank boards are $11 for three.

Sheldon
quadesl.com

 

[Fummelfinger]

What type of diodes are needed for those clamp boards? Looks like some smd soldering is needed.

 

[ferret]

ESL 57s

Hi Sheldon,

Very big thanks for the Osh Park PCBs. I have a stacked pair of 57s, and have been meaning for a while now to get PCBs laid out, but just never got around to it. This is a lot more affordable way to get things done. 'Tis better to wait for these to arrive from Osh Park, than to get them made here - most places here are way too expensive.

AAMOI, I also have a pair of stacked 63s in my collection. The good friend I got my ESLs from (~1998) passed away some 10 years ago, and asked his daughter to let me take them over when the inevitable occured. These still need to be checked out thoroughly before I power them up. Just too many projects waiting to happen.

Do you perchance have BOMs for all the Quad boards that you made available on Osh Park?

Kevin

 

[stokessd]

Yes, the zener diodes are surface mount, but they are enormous surface mount parts.

The Zeners are: BZG03C220-HM3-08 Vishay Semiconductor Diodes Division | Discrete Semiconductor Products | DigiKey

The rectifier diodes are: GP02-30-E3/73 Vishay Semiconductor Diodes Division | Discrete Semiconductor Products | DigiKey

Kevin -

I've got BOM's for everything up on OSH park. I'm slowly re-doing my boards I've sold for years, and dropping them on OSH park. People can buy them at will. I don't get any money from the sale, but I make enough on quad repairs.

 

[ferret]

Osh Park BOM

Hi Sheldon,

I must be bloody blind but I can't find the BOMs on Osh Park. Could I ask you kindly to post the links to the BOMs?

Kevin

 

[AVWERK]

Sheldon, the 57 (rectifiers ) boards on OSH are 2 different versions , one with neons and the other without, and as mentioned the BOM is missing on those in particular.
Which rectifier is used for a 47k serial # ?


Thanx
David

 

[stokessd]

Hi Sheldon,

I must be bloody blind but I can't find the BOMs on Osh Park. Could I ask you kindly to post the links to the BOMs?

Kevin

I'm sorry if I wasn't clear, I have the BOMs, but they aren't on OSH park. That board I linked above only has two parts which I also listed above.

Sheldon

 

[stokessd]

AVWERK -

The 57 rectifier design I have includes the neon isolators. If you bypass them, then the boards are identical to the stock Quad rectifier boards for all the original ESL's. The isolators were added so you can use them if you'd like.

All -

I've got BOM's for the boards, but it appears that OSH park doesn't have an easy way to include them on their site. They want to push that stuff off to another site. Do you guys have suggestions of how to keep them linked?

Sheldon

 

[ferret]

Hi Sheldon,


You can always just post the BoMs and/or schematics here in PDF format. We can just download the ones we need.


Thanks,


Kevin

 

[stokessd]

Hi Sheldon,


You can always just post the BoMs and/or schematics here in PDF format. We can just download the ones we need.

I'll get exporting the BOM's from KiCAD, but while you are waiting the schematics for all my quad related boards are here:

Sheldon’s World

Sheldon
quadesl.com

 

[Fummelfinger]

Hello everyone. I have ordered the clamp boards from Osh Park; they are on their way to Iceland. But there seems to be no way for me to have the zener diodes sent over here for less than a hefty 30$ shipping cost! If any of you good people could spare 20 or so BZG03C220-HM3-08, put them in an envelope and mail to me, please let me know, I would send the money beforehand.

 

[tubesguy]

I'll do it for you. Do you actually have the BOM, and does it specify those parts? I've received the boards and will be installing them in my speakers.

 

[Fummelfinger]

Thanks a lot, that would be really kind of you. Email me at t-arnason@islandia.is so we can sort out the money matters. The types of diodes needed was mentioned earlier in this thread, on june 25. Best regards - Thordur

 

[GeoffW]

Re-opening this thread as I am about to open up my ESL57s for some overdue maintenance!

Does anyone have a source for the clamp boards mentioned above? The link cited to Osh Park no longer works.

If these little boards are not currently available then I'll go ahead and make some, but no point re-drawing & making them if they are still available at a low price. Anyone know?

 

[stokessd]

Man, so much for a permalink:
My Quad Clamp Board

Good luck finding the Vishay 3000v rectifiers I specced above. Last time I checked they are out of stock everywhere, and there is a 94 week lead time.

I use these now, until the vishay ones come back in stock:
https://www.mouser.com/ProductDetail/Rectron/R3000-T?qs=m6PtEeoja6gmP37yljRwMQ==

 

[wout31]

Re-opening this thread as I am about to open up my ESL57s for some overdue maintenance!

Does anyone have a source for the clamp boards mentioned above? The link cited to Osh Park no longer works.

If these little boards are not currently available then I'll go ahead and make some, but no point re-drawing & making them if they are still available at a low price. Anyone know?

At a low price?
Several sources for around $ 80,00 - $ 130,00 for a set of clamp boards.
OTA in UK
ESL Plus in EU
Electrostatic solution in USA