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Fanuc 30th October 2007 09:13 PM

Some Quad els57 questions! - Novice Questions!
 
Hello,

I came across and interesting article writing by Martin Colloms which was written in '84 where he compares it to modern stuff and evaluates some tweaks.

The link is here.

http://www.onethingaudio.com/OTA/9152-OTA-MAIN.htm

Having stands to mount them on seems like a good idea acoustically - Treble at ear level and makes the frame more rigid etc.

But the part that concerns me is the comment by him about not using absorbent material for back reverberation from room acoustics. Something that is a problem with open baffle speakers also.

He advocates in the article that removing the absorbent makes the speaker sound better. Anyone knows with ELS57's there are dust covers at the back of the Quads, so I do not see the logic to this or maybe I am misssing something technically?

PS. I am not acoustic/speaker expert by any means! let alone on electrostats.

Just wondering what people say about this, including home diyer's and any sound technical reasoning (I am not aware off) why this would improve matters.

Best Regards

Kevin

arend-jan 30th October 2007 10:09 PM

Hi,

IMO, there are no real tweaks to make the Quad ESL perform better. Yes, they can be elevated from the floor to get a more realistic soundstage. This tweak will also give you better mid-bass. The middle of the treble panel should be at ear height.

There are two places with damping material: there are some layers of felt behind the treble panel (the element in the middle) which is there to damp the main resonance of this panel. This resonance is out of the pass band but may be exited by the bass panels and can cause the treble panel dustcover to rattle. This felt should not be removed. Then there is a layer of cloth on the back grill of the speaker which is there to lower the Q of the bass panel resonance. Depending on the room and the state that the ESLs are in, removing this cloth may "improve" bass response or not.

Dustcovers have nothing to do with it, they are more or less acoustically transparent.

I think the best way to get the most out of your Quads is to first make sure they are operating in good order and second to move them off the floor and experiment with the proper setup for your room/listening position. Another tweak may be to play them without the front grill.

Fanuc 31st October 2007 12:13 AM

QUOTE]Originally posted by arend-jan
Hi,

There are two places with damping material: there are some layers of felt behind the treble panel (the element in the middle) which is there to damp the main resonance of this panel. This resonance is out of the pass band but may be exited by the bass panels and can cause the treble panel dustcover to rattle. This felt should not be removed. Then there is a layer of cloth on the back grill of the speaker which is there to lower the Q of the bass panel resonance. Depending on the room and the state that the ESLs are in, removing this cloth may "improve" bass response or not.

Dustcovers have nothing to do with it, they are more or less acoustically transparent.

I think the best way to get the most out of your Quads is to first make sure they are operating in good order and second to move them off the floor and experiment with the proper setup for your room/listening position. Another tweak may be to play them without the front grill.
[/QUOTE]


Hello,

Thanks very much for your reply. And some of what you mention I have read about already.

But I take a different tact to you on the issue of absorbants. The damping is there (from what I understand) mostly to absorb reflections from a rear wall - in other words room reflections/reverberations etc. Although what you say is still a legitimate issue.

Have heard of people putting heavily damped curtains/rugs behing there electrostats to absorb/lessen the reflections.

Anyway the Quad ELS57 is marketable a different ELS to some others in that it is mostly a "closed box" solution - if you accept the notion that absorbants cancel in both directions (at least it try's too!) from to/fro the rear radiation.

That's my understanding of it anyway. If I am wrong, I would be most greatful for you and others to clarify certain aspects of the design and ELS's in general. Best way to learn!.

Best Regards

Kevin

harry_at 1st November 2007 07:13 PM

Hi Kevin,

if you want to "learn" something take a look at one of the longest Esl-thread. Some useful tips there from Quad Esl-57/63 and music lovers from the Hongkong area. At the bottom of the page you can click to newer posts.

http://www.review33.com/avforum/foru...4135925&page=1

I like this site,

Harry

AVWERK 5th November 2007 10:02 PM

I have the 57's and as far as listening goes, you should leave the absorbers in place.

The reason came clear when I obtained some ML SL3's.
These require a considerable distance away from the back wall because the rearward output bouncing off the back wall hurts the overall coherence.
Even though the ML require a tow in (a flashlight on them from the listening seat about 1/3 in from ctr.) you still can hear the damaging effects this causes until you pull them out at least 3 feet from the back wall.

ML would do well to absorb the back wave but then, they would loose that cool see thru factor that sells alot of speaker's

Raising the Quad up on stands as suggested does help the transparency. A equal distance triangle on setup should make them disappear quite nicely with the best recordings.

Regards
David

SY 5th November 2007 10:17 PM

Quote:

The damping is there (from what I understand) mostly to absorb reflections from a rear wall - in other words room reflections/reverberations etc.
According to Peter Walker, the damping was put there primarily to control the Q of the fundamental bass resonance. He didn't seem happy with the idea of removing it.

frankwm 3rd December 2007 09:10 AM

Another ESL-57 mod - more than one of them!
 
I've owned '57s for about 12years; usually run from 303/405.2 - or II's.
They 'died' on me after 2days (nice mint Black pair) - but the previous owner clearly had doubts about the sound as, acoustically, they were 'mismatched' - having differing/no absorbent behind the panels.

After nearly 2years of experimenting to 'voice' them correctly (IMO..) the following was the outcome:-

Obtained the one-piece acrylic tweeter felt/new rear Hessian from QUAD (this was in '95).
The Tweeter has a mass of 'reflections/resonances' caused by the enclosure - the sound differs as you listen from top to bottom (venetian-blind effect).
This was cured by using thin acrylic felt around the side bass panels (attached by double-sided tape - the foam verticals moved away from the bass panel edges - so as to create a slight 'flare') - also the Alu. top/bottom retainers.
There's a Cavity Resonance @ the internal rear bottom of the Treble panel - cured by slightly cutting the thick acrylic treble felt about one-third from bottom - enabling the felt to be equ-distant from top to bottom.

The main problem with the '57 design is acoustic integration of bass/treble panels.
Eventually I found the 'cure'.
This was to use circa 2mm WOOL felt - TENSIONED on 3sides (+ side 4 -treble panel - slightly) behind the bass dust cover.
This has the added benefit of making the frame acoustically 'dead' - and removes from the acoustic response the large transformer (its presence can be 'felt').

Another added benefit is that close proximity to the rear wall (in a small room) is no problem.

There is Absolutely No 'dulling/smothering' of the sound due to the above method - quite the revers,actually, an, in nearly 10years I've not felt inclined to ever experiment further...surely a good sign!
The original legs were kept - no problems with the original arrangement that I can hear...

Hope this is of interest!

Frank

oshifis 4th December 2007 01:48 PM

Re: Another ESL-57 mod - more than one of them!
 
Quote:

Originally posted by frankwm
The main problem with the '57 design is acoustic integration of bass/treble panels.
Eventually I found the 'cure'.
This was to use circa 2mm WOOL felt - TENSIONED on 3sides (+ side 4 -treble panel - slightly) behind the bass dust cover.
This has the added benefit of making the frame acoustically 'dead' - and removes from the acoustic response the large transformer (its presence can be 'felt').

Frank, sorry but it is not quite clear what you have done (perhaps I have to improve my English...). Could you describe it so that I understand? I am very interested in any improvements that can be done on the ESL.

Thanks,

Laszlo

frankwm 4th December 2007 08:51 PM

Hello.
Well..maybe (without pictures) I can elaborate.

The QUAD '57 clearly suffered from treble 'diffraction' effects, due to the treble-panel being mounted 'behind' the two bass-panels (my reference to a 'venetian-blind effect') - ie the output is 'phasey'/changes as you move your ear (close to the panel) up & down.

I'd been using B&W DM7's for over 15years - which have an external tweeter - so the diffraction in the QUAD by comparison was obvious.

I bought the thin acrylic for the treble (used, as described) and the wool for the bass..which I initially used loosely-draped behind the bass-panels - two layers - then one-layer..but that wasn't at all 'correct'...even cutting pieces to attach/line to the side/bottom with double-sided tape (used for the acrylic-felt for the treble,also).

The way I did what proved to be The Last 'mod' was to remove (again..) from their places the Transformer and Mains Rectifier.
Using over-size Brass 'Drawing Pins' the single layer of felt was placed immediately behind (but Not Touching..) the dust-cover/s.

The felt was cut so that it was slightly larger than the panel.
It was attached by means of about 6 to 8 drawing-pins per side.
- I think I did the outside first - tensioning the wool (acrylic is no good for this..) firstly with just a top/bottom drawing pin and attaching it to the frame by being pinned - making use of the 'overlap' - L -if you can imagine the bottom of the L being where the pin/s are placed [sides/top/bottom] - the vertical being the main wool 'panel'.
Then pin the top/bottom of the felt to the frame in a similar fashion.
The treble panel only allows a few pins to be used - but that's OK.

All I can say is that the end result (combined with the treble mods) allows the speakers to become 'seamless'/'uncolored'..
The frame is also quite 'inert' (ie - it no longer 'wobbles/resonates') - as the tensioned wool is also absorbing the spurious energy...as well as providing a similar 'acoustic environment' as the treble panel has.

[It is also a good idea to make sure the transformer is well screwed onto the frame - as that acts like an 'energy sink'].

I did try the QUADS without any damping for bass/treble - with/without the hessian, etc, etc..spent 18months 'messing about'..but my (very easy and very cheap 'mod's') I've never since had the slightest thought of altering - I just clean the front dust-covers every year or so.

I initially bought the 'treble clamps' too from QUAD - and have retained them - they don't seem to 'damage' the sound at all.

Hope that's clearer !!

Frank

frankwm 4th December 2007 10:48 PM

To give a better idea - I've uploaded a sketch to my vintage-cambridge-audio Google Group:-

Listed as :- " TEMP FILE my quad 57 mods.jpg "

This link should take you there.

http://vintage-cambridge-audio.googl...B280mdiAJ1YANw


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