Bizarre ESL

[Audiofool]

Sorry, could not upload the scan from the HFNRR review: will try later

J.B

[moray james]

That's exactly what I ment but failed to convey. Both bass panels oriented horizontally stacked one on top of the other. The mid/tweeter panel would then sit atop these two panels and would be centred and vertical. Hope that makes sence. Regards Moray James.

[bear]

You should find the original articles by Peter Walker that were in Wireless World back in the 50s...

The positioning of the tweeter panel with respect to the midbass panels was very well thought out in the original design.

Think MTM? ( but horizontal...)

They're not curved, btw.

In a normal listening room, you'd likely benefit from making the speaker have the tweeter being vertical, that giving better horizontal dispersion... of course, if you stand up...

Which is why the original was more or less designed to sit on the floor, tilt back so that no matter where you were the highs would hit ur ears...

_-_-bear

[lpd]

I appreciate all of the answers to this riddle of mine. I am going to rebuild new frames that will be exact copies of what I have except the panels will be rotated 90 degrees. I am going to experiment with the stand and see what sort of difference it makes. I hear that it cleans up the top end, but sacrifices some bass in doing so.

[EC8010]

I_forgot: Your frame is worthy of comment; it is stunningly ugly yet beautiful because it is an elegant engineering solution.

[Majestic]

Originally posted by EC8010
I_forgot: Your frame is worthy of comment; it is stunningly ugly yet beautiful because it is an elegant engineering solution.

Actually... if those pipes are hollow, sand-filling them could pay quite worthy dividends

[SY]

That's something I tried for the frames of my ESLs when I first got them. It was less than successful- the problem is that the added mass makes the PVC very flexy at the junctions. Now, my panels are much taller, so perhaps it's more viable for something like IF's speaker.

I also tried it with cement and rebar filling (didn't cure right and still had the flexy problem).

[Majestic]

Originally posted by SY
I also tried it with cement and rebar filling (didn't cure right and still had the flexy problem).

Hmmm.... Mental note not to try that then.

I did build a pair of floor-standing 'box' 2-ways filled with 1/3rd of concrete. Worked a treat!

[I_Forgot]

The tubes are empty, mainly because I will be moving to Phoenix this summer, and it's going to be enough trouble to move thigns around without adding another 50 lbs of concrete or sand to the speakers.

I agree, they would probably get flexy. The flex could easily be controlled by changing the frame configuration in favor of a stiffer design. With empty pipe it seems stiff enough. If the goal of filling is to eliminate cavity resonances, that could be done by filling with rolled up newspapers or other less massive but space filling stuff.

I_F

[Brian Beck]

I would not think that the added mass would lower the stiffness of the PVC frame; it will just make the resonance frequency MUCH lower and it will SEEM to wobble more in your hands than it would with the lower amplitude buzz of the higher resonance of hollow PVC. Granted, the Q might be higher with filled pipes, but if the resonance is at 2 Hz or so, who cares? If the frame doesn’t fall apart due to the weight, the sub-sonic resonance should be excited less by the speakers’ motion than would a resonance at, say 200Hz. Remember, higher stiffness implies higher resonant frequency. Maybe, just maybe, a “floppy” heavy PVC frame won’t react much to diaphragm motion, since the mass produces such a high mechanical impedance at audio frequencies.