Rhosonics HD-1 Hybrid Electrostatic speakers

[Apache5]

Hi, good evening! I recently got my hands on a pair of damaged hybrid electrostatic loudspeakers. I want to try to repair them but I can't find any information about the model and brand. I can start repairing them without this information but it's not clear to me that it's worth repairing them.
They are made in the Netherlands by Rhosonics Acoustical Systems and are model HD-1. I have found a company called Rhosonics Analitics, in the Netherlands, but they have already told me that they are not.
Does anyone have any knowledge of this brand, the model or any indication of where to look?
Thank you very much.


Arnau

 

[Gerald Jansen]

Hi, good evening! I recently got my hands on a pair of damaged hybrid electrostatic loudspeakers. I want to try to repair them but I can't find any information about the model and brand. I can start repairing them without this information but it's not clear to me that it's worth repairing them.
They are made in the Netherlands by Rhosonics Acoustical Systems and are model HD-1. I have found a company called Rhosonics Analitics, in the Netherlands, but they have already told me that they are not.
Does anyone have any knowledge of this brand, the model or any indication of where to look?
Thank you very much.


Arnau

Hi Arnau,

I have never heard of the name "Rhosonics Acoustical Systems", but maybe this info will point you in thee right direction:
http://www.audiocircuit.com/Home-Audio/Syntaxis.

Take care, G

 

[Apache5]

Thanks Gerald! It's a very interesting site! I was looking at it because, indeed, there is a lot of information about electrostatic loudspeakers, and others. Nothing about Rhosonics...
It also has a forum where I thought of asking but there is not much activity so I thought of asking here first because there is more movement and there are many knowledgeable people contributing and helping for many years.
No doubt I will get a lot of information from this site if I undertake the repair of these HD-1.

Thanks!

Arnau

 

[Gerald Jansen]

In my Safari browser it showed contact info (address, email and phone nr) for Rhosonics Acoustical Systems; top right of the page. . .

 

[Apache5]

Hello Gerald! With which search engine? I only get rhosonics.com to those I already consulted....
If you can pass me the details I would be very grateful.

Arnau

 

[Gerald Jansen]

There is no website of "Rhosonics Acoustical Systems". Please revisit the url I posted earlier.

 

[Apache5]

Oh, I'm sorry, I didn't understand you, now I've seen it!
Thank you very much for your patience!

Arnau

 

[Disco Volante]

Worth repairing is a bit of a philosophical question. Electrostatics are sensitive devices and fiddly to repair. There's a whole lot of opinions and "schools" just discussing how to make the right foil for the diaphragm..
Fix them to listen and enjoy, it may very well be worth your while. ESL's deliver big time in terms of midrange; the lack of distortion is remarkable. (I own a pair of Quad ESL57)
What's wrong with them? Post some pictures!
Happy tinkering;-)

 

[Apache5]

Hi! I have not yet had them in the workshop and have not yet been able to evaluate the extent of the damage. They are in a rather poor state. I know that some of the bass speakers are open, I'm worried that they are made of a "special" material. When I have them in the workshop I will see the general working condition. I have taken some pictures.


Arnau

Arnau

 

[Disco Volante]

Wow, so what looks like 2 Scanspeak or Vifa 10" units running open baffle and a electrostatic mid-treble section.. Interesting.
Looks like some kind of dust cover or damping foam on the rear side has entirely disintegrated.
I can't see any signs of arcing in the ESL system though, but you'll get a better look soon enough;-)
At least the dynamic units look intact. A lot of these had that sort of scruffy look even when new.
Fun project!

 

[Apache5]

I have already got the speakers in the workshop. The rear Foam has not disintegrated, it is unhooked and I removed it to take the pictures. I don't know about speaker brands and thanks to the Disco Volante's indication I could find that the woofers seem to be trans-speak 21W/8555 (the labels are erased). Two of the 4 woofers are open but I was lucky, the cut was just after the braids and not in the coil. I was able to repair them. I still haven't dared to connect the power to test the electrostatic speakers, from what the previous owner told me I don't think they are working properly, he talked about "leaks". I'll let you know how it goes...
Thanks!!

Arnau

 

[Disco Volante]

Aha, so classic ScanSpeak units. Made in Denmark;-) but smaller than my guess at 8". Good stuff, but yeah, they sometimes break a litz-braid. They have rather heavy membranes and might benefit from being rotated a half turn.

See if you can get a look at the powersupply, give it a good cleaning. ESLs suck up a lot of dust over the years and can get leaky (lose voltage).
My old Quad ESLs just needed cleaning to get back to life: faster charging and higher efficiency (=more sound!). You'd want to leave them on for a half hour and listen for crackling sounds or other misbehaviour as they charge the membranes.
Happy tinkering!

 

[Apache5]

Well, I have inspected the psu and everything looks clean and visually correct. I plugged the speaker into the power supply. Almost immediately I started to hear crackle noises like arcing between the ELS parts. Maybe it's dust between the panels? I remember reading that some of them can be washed but I'm not sure. I'm going to look into it before I disassemble something and inadvertently damage something.

Arnau

 

[Disco Volante]

Arcing should only be happening in overload situations. Do you have an extra layer of film on the very front and back of the ESL elements? I can't really tell from the pictures. If not, I'd say you're right in assuming dust between the membrane and stators...
The PSU looks impressive, that's a large voltage-ladder!
Cheers, V

 

[Apache5]

Ok. I have inspected the ELSs more closely. There are two panels per speaker. One of the panels has the membrane perforated in a couple of spots, bad thing for sure (you can see it in the second picture). I've taken the panel apart and it looks like the assembly is not designed to be disassembled and cleaned (third picture). The one that is perforated I'll probably have to look for a place to repair it. The other 3 that look dirty I don't know if it's advisable to use distilled water to see if they can be cleaned. I saw that someone cleaned them with distilled water by pouring it over them and letting it run but I think it was on a Quad ELS and maybe the membranes can be disassembled separately.

 

[Disco Volante]

The Quads are quite different that way. They have an extra layer of film back and front to keep dust out of the electrostatic charge. Also, they're built on wooden frames and relatively simple to disassemble. I'm guessing the front and rear covers on your speakers are meant to perform the task of keeping dust out of the HT.
It looks like your panels are glued together?
The intact ones could probably be cleaned with a bit of compressed air, just take down the pressure so you don't put all 6 Bars in there;-)