Quad ESL help appreciated!

[sq225917]

You could always add a small sub and run it out of phase. One with parametric eq should allow quite accurate nulling.

[sq225917]

Or build a Helmholtz resonator to do the same.

[Barry]

Reversing the polarity on the bass section of one speaker will almost certainly cause cancellation and reduce the perceived bass quantity, but I'm pretty sure you'll also get weird phase effects that'll mess the sound up.

One of the design features of the Quad 57 is that all the panels are time-aligned. Certainly inverting the phase of one of the bass panels will mess all that up.

[Opti-cal]

You could always add a small sub and run it out of phase. One with parametric eq should allow quite accurate nulling.

Excellent suggestion, I have a small REL with a phase switch which could do the job. Cheers

[Opti-cal]

Or build a Helmholtz resonator to do the same.

Just noticed your kit there Simon, looks like a lot of stuff I like. Paradise stage and NS1000's. Great stuff.

[Pigmy Pony]

Why can't ESL's be sited close to the rear wall? Is the problem to do with sound reflections? If so, surely you could place something super-absorbent as close behind the speakers as you like, as the sound won't be reflected back. Something like large picture frames with something thick and woolly attached. Then you can hide as much absorbent stuff behind those panels as you want - it's just a dead space anyway. Should be cheap and easy enough to do, then try an A/B comparison with the out-of-phase thing.

[Opti-cal]

So after a heavy experimentation session last night . . . .

Swapped in some different speakers to test the bass resonance in the room. They are 12" drivers in Tannoy cabs with Tannoy HPD's on top in separate enclosures with a custom crossover letting the 12" take care of lows and the HPD's the mid/highs.

Even poked right into the corners of the room I was getting very little resonance compared to the quads - I assume because nearly all of the sound from these speakers is projected forward, including from the front firing bass port.

They sounded pretty good and even better when pulled out a bit and given some room.

This indicated to me that the room could facilitate the quads with some further damping behind and given some more clearance to the rear wall (as suggested).

So back in went the quads, I rejigged the various foam tiles/pillows/blankets I had back there to provide a "thicker" spread of absorbing material as well as pulling the quads forward a couple more inches or as much as possible before they started to occupy coffee table position (middle of the room!).


Improvements were obvious but still not where I wanted them. Still the boom was there at medium volumes but the imaging and delicacy of the detail was back to as good as I can remember.


Then I decided to try them with a cheap (but has served me superbly) EL34 amp I had laying around. I also specifically put output tubes in it that I felt were bass-light before as hopefully they would be just the ticket to reduce the bass output.

The result of doing this was extremely positive. I'd forgotten just how nice this little amplifier could sound. The tubes I had found superb for midrange before and were extremely "airy" but were so light on the bass I rarely used them.

Now with the exaggerated bass output in my room they sounded very good indeed. They are a bit on the "chimey" side but this I can live with compared to boomy bass.


Using the 4ohm taps really helped clean up the bass from this amp too, much more so than on my 2a3 amp.


My room is a complete mess now with amps and speakers all over the place but I managed to end up somewhere near the sound I was missing.

With a bit more tweaking and experimentation I think I will get there.


Thanks for all the ideas and input guys, your responses and ideas have been superb.

Can't wait to get home tonight and continue tweaking and I don't have to sell my favorite speaker of all time!!

It just reiterated to me how damn good a speaker these are. I know its said a lot but I've yet to hear strings, wind instruments and female vocals on acoustic recordings, recreated in the way the 57's do.

Cheers

Chris

[Opti-cal]

Why can't ESL's be sited close to the rear wall? Is the problem to do with sound reflections? If so, surely you could place something super-absorbent as close behind the speakers as you like, as the sound won't be reflected back. Something like large picture frames with something thick and woolly attached. Then you can hide as much absorbent stuff behind those panels as you want - it's just a dead space anyway. Should be cheap and easy enough to do, then try an A/B comparison with the out-of-phase thing.

I did try some large canvas panels behind the speakers and also on the wall directly behind. It did dampen the bass somewhat but it also messed with the imaging. The rear panels reflect the sound intentionally so if you take that away to my ears it loses something. Layering and depth of soundstage are certainly reduced.

I reckon the answer is in increasing the amount of absorbing material in the corners and along the walls of the room so the sound can exit from the rear of the speaker but the bass will be dampened by this material. That seems to be working so far anyway.

I have also tried them close to a flat rear wall in my lounge and they went a bit dull and flat. Maybe I'm getting a bit of a reverb effect in my loft from the pitched roof also which I've grown a custom to and tweaked the system and speaker positioning to suit. It might have lost some accuracy but I do get a really 3D effect which I believe is partly to do with reflections from the rear panels into the space behind which is then projected back by the pitched roof.

To me with an all tube setup it sounds incredible. Like I say possibly colored and inaccurate but harmonically very pleasing.

Cheers

[Macca]

You could try swapping the speaker cable for some really thin stuff, bell wire type. That will reduce bass output. I don't think you have enough space to build a bass trap large enough to absorb the problem frequencies.

[walpurgis]

Just bung a graphic equaliser in!