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enilsen 19th April 2007 04:44 PM

RTR DR-1 (circular electrostatic panel)
RTR DR-1 omni-directional loudspeakers.

I've tried in vain to find out more about these speakers on the internet. I found one reference where they claimed they sound better than the original Quad electrostatics.

In all curiosity I really want to know more about the circular electrostatic panel used.

Here is a single reference to a pair for sale on ebay but no mention about the circular electrostatic panel or what it looks like.

DR-1 for sale on ebay

frank ziel 20th April 2007 11:13 AM

not much but...
go to Speakers/Electrostat/Brands/RTR

enilsen 20th April 2007 01:55 PM

Thanks Frank,

Your right, there wasn't much info on these speakers. There appears to have been an unofficial site by Andrť Ferchau which the link doesn't have access to.

I'm really puzzled why there is so little information about a speaker with such unique properties. This cylindrical electrostatic speaker (omni-directional) could produce sound from 300 Hz and up and had a built in class G amplifier.

Hmm! Resembles qualities found in MBL speakers of today.

If it hadn't been for the association with other well known speaker builders (* Crown * ESS * Fulton * Infinity * Wilson ) I would have thought this was bogus technology. :xeye:

Brian Beck 21st April 2007 05:10 PM

This is an interesting design that I vaguely recall, but probably never heard. So I can't directly help you with info on this model.

RTR was very well regarded for their ESL tweeter drivers, a variation of the Janszen design. Thatís why the makers you listed selected them. I owned a pair of Fulton FMI-6 (RTR-6) tweeter arrays, and they produced the most glorious highs I have heard then or since (when driven by tubes). But they were crossed-over (by a series cap only) at a very high frequency to the Fulton cones down below. No attempt was made to run them down into the mid-range.

RTR was not as well regarded for their complete speakers systems. I canít say anything about this particular model, but if it uses the same tweeters that I loved, I doubt they would have worked as well down to 300Hz. And who knows about the quality of the built-in amp(s)? The double enclosure bass system is intriguing however. This speaker might sound very nice (repaired) or not. But my point is just that the RTR reputation was really built on excellent stand-alone ESL drivers.

planet10 21st April 2007 10:05 PM

I have owned the ESL panels that come in those... they are OK, but i couldn't get real excited about them.


enilsen 23rd April 2007 01:03 PM


Originally posted by planet10
I have owned the ESL panels that come in those... they are OK, but i couldn't get real excited about them.


You wouldn't have any photos of those ESL panels Dave?

planet10 23rd April 2007 08:08 PM


Originally posted by enilsen

You wouldn't have any photos of those ESL panels Dave?

I moght have a physical photo somewhere -- that was 30+ years ago...


el`Ol 26th April 2007 09:14 AM

The discussion about an omnidirectional ESL has been there several times. But as far as I know nobody here has realized one yet. One conclusion of previous discussions was that a cage with vertical bars is not practicable because every element would beam and there wouldn`t be a homogeneous sound field. I have played with the following idea: Take a spring of a car, pull nylons over it, then use latex milk or fluid rubber for bicycles mixed with graphite powder to seal it. I believe the usual mylar would have too much tension for the small distances given by the spring, but maybe I am wrong. Anyway, getting a mylar hose in the right size might be complicated.
Till now I don`t dare to try, because I have no experience with ESLs and I am too uncertain about the result.

enilsen 26th April 2007 11:16 AM

It's interesting you should bring up the point about the beaming effect. Other omni-directional speakers like mbl don't really mention the problem at all. Is this because the problem can be solve or addressed somehow?

What intrigues me more about the ESL cylinder design is the fact that the sound that is sent in all the other directions and should give a more spatial impression when bounced off the walls or reflected. I would hope the beaming effect would be less apparent under those conditions.

Maybe Dave can remember if there was a beaming problem with these speakers?

el`Ol 26th April 2007 11:31 AM

The MBL loudspeakers are multi-way systems, i.e. for higher frequencies you have narrower stripes, so the stripe width stays small compared to the wavelength.
My personal belief is that an important point about omnidirctionals is that they have the same acoustic center (in projection on the horizontal plain) over the whole frequency spectrum and this is relevant because the wavefront radius is audible in form of interaural time delay. The higher proportion of indirect sound in my opinion is a secondary benefit.

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