sub for Quad ESL 988

[rbl]

surely though a small cone has to move further and therefore faster (and therefore require greater acceleration) for a given volume level at a given frequency? Don't these "drawbacks" of a small cone negate the benefits?

[Skunk]

It's simple inertia.

Assuming they're made out of the same material, a small cone takes less
force to move than a big cone as it's lighter, and has less air
resistance to push against than a large cone.

R.
BEng(Hons) Electroacoustics

Not that I'm disagreeing, just trying to get an accurate mental picture;

Disregarding the force required to move the cone, a small cone is going to have to move further than a big cone, in order to give equal frequency response. The 8" extended to its x-max would produce the same amount of bass as a 15" at 1/2 its x-max. I would think it depends more on the individual driver's impulse response and the amount of bass needed in the room, moreso than the size of the driver, as to which is 'faster'.

The return resistance being greater and making the larger driver slower to return makes sense as well though, which is why I thought most audiophiles preferred sealed boxes- the cone don't move as much.

For quads maybe a DIY dipole sub (like the bottom half of linkwitz orions) would be a good option. Some assembly required.

[creativepart]

By "fast" we're talking transient response to a signal. Planars are "fast" because they are accelerating a thin ribbon of mylar and the magnet for this ribbon is evenly dispersed along the length of the ribbon. The ribbon is only moving very slightly. So, it can respond very quickly to a signal.

Cone speakers are so much larger in comparison and respond from the center to the outside of cone.

We're only talking about small fractions of milliseconds here. But since the Quads are such a different technology than a cone speaker it is better to pair them with a sub that won't smear the sound by being ever so slightly "behind" the rest of the frequencies being radiated.

[pfarrell]

Skunk wrote:
> Disregarding the force required to move the cone, a small cone is going
> to have to move further than a big cone, in order to give equal
> frequency response.

Not frequency response. A small cone and a large one can make the same
frequency with the same motion.

The smaller cone will have to move farther at the same frequency to get
the same level of sound.

I'm not sure that this matters. When I was working as an engineer, we
would spend hours arguing which kept you dryer: waling in the rain or
running thru the rain. Walking clearly exposes you to longer time, but
rain only hits a small area. Running cuts the time exposure, but sweeps
a larger area (your whole body).


--
Pat
http://www.pfarrell.com/music/slimse...msoftware.html

[opaqueice]

Skunk wrote:
> Disregarding the force required to move the cone, a small cone is going
> to have to move further than a big cone, in order to give equal
> frequency response.

Not frequency response. A small cone and a large one can make the same
frequency with the same motion.

The smaller cone will have to move farther at the same frequency to get
the same level of sound.

That's exactly what Skunk said. Frequency reponse, meaning the level of sound produced given an input with some frequency at fixed level.

I'm not sure that this matters. When I was working as an engineer, we
would spend hours arguing which kept you dryer: waling in the rain or
running thru the rain. Walking clearly exposes you to longer time, but
rain only hits a small area. Running cuts the time exposure, but sweeps
a larger area (your whole body).

Someone actually went to the trouble of working that out - evidently given some reasonable assumptions about the distribution of rain drops, the answer is you should lie on your back (maybe on a skateboard) and go around 15 mph. Very practical...

As for speakers, maybe "fast" is the wrong word. If it's a question of a delay it's the phase response you're talking about, that's a standard thing measured for speakers.

I have heard Quads, but I think the better imaging may have more to do with the pattern of sound radiation than it does with phase.

[Robin Bowes]

Pat Farrell wrote:
> Skunk wrote:
>> Disregarding the force required to move the cone, a small cone is going
>> to have to move further than a big cone, in order to give equal
>> frequency response.
>
> Not frequency response. A small cone and a large one can make the same
> frequency with the same motion.
>
> The smaller cone will have to move farther at the same frequency to get
> the same level of sound.

Pat has saved me the trouble of responding!

R.

[pfarrell]

rbl wrote:
> Can anyone recommend a subwoofer to match the Quad electrostatic 988
> speakers, for use with both HT and music? My room is 15' x 18' so I
> don't need anything particulalry loud, but something that blends in
> well. Am thinking of the TBI Magellan VIII or the Velodyne DD-12, but
> open to suggestions. Has anyone tried these combinations?

I don't have Quads, I'd love to, but they need more room than I have.
I have a Rel Stadium sub, and it is very musical.

I recommend checking the archives at Stereophile, TAS, etc.
I remember reading many articles about how hard it is to match
a sub with Quads and other panel speakers.


--
Pat
http://www.pfarrell.com/music/slimse...msoftware.html

[konut]

I don't own Quads. I do own a pair of single driver speakers, the Omega Aperiodic 8 which uses Visaton B200 8" drivers. So aside from being a point source very resolving driver, it has nothing in common with the Quads. I've paired these with a Rocket UFW-12 sub avaliable from AV123. This sub includes an external unit called R-DES. Its a line level 5 band parametric equalizer that can be programed by hooking up a USB cable to your computer and running the software included. Its very effective in not only integrating the sub to your stereo pair, but taming any peaks and nulls in your room. Its an IB design so its subjectively fast, to my ears anyway. Very musical. I love mine.
http://www.av123.com/products_produc...rs&product=8.1

[Skunk]

That's exactly what Skunk said. Frequency reponse, meaning the level of sound produced given an input with some frequency at fixed level.

After posting I realized I actually meant to say 'both drivers producing the same SPL at a given frequency', which Pat was quick to correct. In this case the smaller driver would require more motion, and would have to have a better impulse response, in order to match the speed of a driver producing the same SPL at 1/2 its x-max. Given similar impulse responses, the larger driver would be at rest sooner than the small driver.

Imagine how little a woofer the size of a kiddie pool would have to move to produce a 100dB 30Hz tone, compared to a normal woofer. It would be like a planar woofer, i.e. fast :-)

Again, not trying to insist I'm right on this, but even creative part says: "The ribbon is only moving very slightly. So, it can respond very quickly to a signal". So what is this effect that causes opposite results in large ribbons versus large woofers?

[darkglobe]

Hello all,

I own a set of 63's, which the 988's are simply a "newer" version, read: now made in China version of the 63's. The 989 have two extra panels (6 instead of 4) which deliver more bass.

I believe these electrostatics are usually considered fast due to the light weight of the material that is being driven, there are no wires, coils or magnets attached to the mylar, nothing other than a thin layer of graphite type coating to help reduce charge migration, thats it. Conventional speakers consist of all kinds of materials, from poly plastic, carbon fibre, titanium and now kevlar. All this is MUCH heavier than a sheet of unhindered 2u mylar. (The Quad mylar makes plastic food wrap look like a persion carpet in thickness for comparison)

This all equates to no / low speaker intertia, therefore in theory, faster, more accurate response.

FYI: I repair ESL's.

These speakers are very flat on the EQ, and are very natural and hair raisingly revealing. However, for the rock music fan who loves bass, they simply cannot deliver the SPL. They are also not overly efficient (~86 dB IIRC).

Also, amplifiers that don't like strange impedence loads, i.e. drug store brand amps, need not apply, the amp will likely get smoked. (the impedence drops to below 2 ohms at ~ 18K Hz mark and the protection mechanism in the speaker does its job by shorting the speaker inputs, delivering a 0 ohm load to the amp)

Simply put, to get more bass out of the 63 / 988, your options are:

1 - Upgrade to 989's (or the newer 6 panel ones w/ the pretty brace on back, cannot remember model off top of head, sorry)

2 - Gradient. If you are looking for a sub, this is it, period. If you find one, make sure you get the gradient crossover also.

Now for other considerations which I've tried with no / limited / odd success:

1 - the 63's / 988's are not very rigid, and flex a little with high SPL / bass. You can either use pony up for some Arcici stands or put a stack of magazines on the speaker tops to increase mass, or make your own stands.

2 - Speaker placement. Gradients are dipoles because the Quads are dipoles. Try placing them somewhere in the room / in respect to the wall to attempt bass reinforcement. Play your favourite music and move about the room also helps find the best spot.

3 - With strange success, you can try a crossover like the Bryston 10B and combine w/ a mirage bi-polar speaker, like an OM-200 or 400. With the phase adjustment on my 200, I was able to better match the "speed" of the Quads and make it a little more natural, but I don't have a 10B at the moment and therefore I have overlap of the lower freq, not quite right, OM-200 back to HT room.


Thats my 0.02$ worth.

Cheers!