DIY Electrostatic speakers Audio Transformer???

[pmscompany]

Hi, mmm my english is very bad. What audio transformer, is possible uses for basical Diy Electrostatic speaker.

I lieve in Chile, mmm not possible buy a audio transformer in online. Chile have a industries work transformers... What is a carracteristics for buy a similar or order or work a similar.


Thanks !

[Calvin]

Hi,

if You are using ESL-panels just from app 200Hz upwards, You may try with standard toroids. In Europe we have 230V/50Hz power supply. A couple of 230V/6V toroid transformers gives an transformation factor of 1:76 (in practise it will be a bit lower, around 1:68 because of losses). I use a couple of 230V/6V on a 50VA-core, connected in series on the 230V-side and parallel on the 6V-side with a panel of 25cmx125cm and 1.2nF. Bandwidth is greater than 20kHz and up till today they work perfectly. You might even get lower in frequency by using trannies with bigger core, but an appropriate panel would become quit huge. You can connect more trannies in series (230V-side, 6V-Side always in parallel) to get higher transformation-factors. A quad of trannies would give app 1:150.

jauu
Calvin

[pmscompany]

Thanks, I have a toroidal 220v--->6v (Chile have 220v at 50Hz). My transformer have 2 in and 2 out ??? What is the mode of conection, for ex. http://sound.westhost.com/p105-f4.gif 3 point out, my toroidal transformer have a 2 out. What is the mode of conection to EHT and Stantors.

U have diagram of conection ???

Saludos

[Bazukaz]

Hi,
I think it should look like this.
You need two transformers for each panel. Note : between EHT "-" and "membrane" there must be ~20 Megaohm resistor.
I have bought a pair of 80W 220:12V trannies. They start to saturate at input voltage of 13V at 50 Hz. I think that slightly higher crossover point may be better(i am thinking about 250-300Hz , if i split 12V secs into 2x6V) , because it would keep the core saturation lower.

Regards,
Lukas.

[pmscompany]

Thanks, I buy in a week a 4 toroidal transformers 220 to 6v have a very good price...

A question, What is a max. power (watts RMS) for speaker ???

Is possible uses a passive crossover for cut a frecuence (in 220 to 440 Hz depending a result). And uses other spekers for compensation mid bass and bass. Total a hibrides speakers 2 ways (ESL for mid and high's and woofer for mid bass and bass).
Or is necesary uses two amps??? Bi-amp ???

Salu2

[Bazukaz]

Hi,
Max. power depends on panel and transformer design.~100W RMS amplifier should be ok.
I think an active filter with at least 12db/oct rollof is better than passive. In this case you would need separate amplifiers for both ESL and dynamic loadspeakers. One more thing : add ~0.7 - 1 ohm resistor between amp's output and transformers.This will make life for you amp a lot easier .

Regards,
Lukas.

[pmscompany]

100 w RMS good power for listening music in a house!!!

I speak via e-mail with Rod Eliot the ESP. He uses a tradicional 100v 20w transformer for PA spk.

http://sound.westhost.com/project1053.htm

The combination of transformer have a ratio 100:1 v/s toroidal 230/6v 1:76, (desgin for a MINI ESL PANELS).... Umm what transformer recomend (toroidal or PA ) for my ESL's and what dimention, recomend for cut my`s grilles and work a spk's.

I buy a chinenses speakers for a woofer. 8u$ for woofer. Good sound, 8" diametre, good magnet... Have a neopren paint cone, for low distortion and water protection. Flex edge foams (spume material)... Good sound for a very low cost !!!
I test a next week in Anecoique camera in my University. For add small factor and responce, For correct calculation the cabinet.
The woofer have solo indications of a sensibility (89 db a1m), 8 ohm impedance and 150 watt max. (mmmmm i test mmmm 70 watts rms max, 130-140 program, 150 peak, hehehee) the horrible is a spec a speker. The chinenses have horrible writing a spec. The spec not correspond a reality.

saludos

[Calvin]

Hi,

this is an example what You could do.



The panel is housed in a aluminium profile frame. Below the panel will be the housing for the electronics (the bass You see is omitted). The Bass-tower is a stacked 8-driver dipole bass with 6.5"-drivers.
The crossing over will be done active and 2 amps will be housed in the electronics cabinet too. So this design is fully active.

But You can try to crossover passively equally well.
Here´s something I tried.

A) and B): pure panels response
C) Filter response
D) and E): Panel +Filter response
F): Response of panel + different Filters (pure, Panel+ 50µF, panel +50µF+1mH/1Ohm, panel + 50µF+1mH/5Ohm). The comparison to ML´s Prodigy panel shows two differences. The higher Fs of the Prodigy, which is possible because they use a membrane 4 times as thick as I use and the earlier rolloff at the uper end, where my lighter merane shines. Apart from beeing double as wide as my panel and featuring a thicker membrane, both panels are very similar.
Placing the crossover frequency of the filter right at a point between the panels ground resonance fs (which is ~170Hz in this case) and ~1kHz (where the acoustical short ends) and let it swing over a bit (Fc ~350Hz, high Q) as You can see in the filters response curve, You get a very linear response down to the panels fs with the best possible efficiency. Thats the way MartinLogan did it (comparison ML-Prodigy and my panel). Though this solution looks marvellous on paper and it works in practise, I find that the sonic footprint of the panels resonance is audible. Too the long decay in step response and raising distortion below 300Hz of the panel is of no good. Still You may try this first, as it is a simple solution and squeezes the max out of the panel.
Don´t wonder about the falling frequency response. Measured in nearfield, this response is Your ideal target!
I´d suggest though, that You filter the panel such way:
- linearize Impedance --> use a 15-22Ohms high Wattage resistor in parallel, or a specialized RLC-net.
- use a Notch filter to compensate for the ground resonance
- adjust high-frequency response wth a small valued high wattage resistor
- design the HP filter as 1st or 2nd order with an fc min. double the panels fs(here it is ~550Hz electrically giving -6dB@350Hz acoustically)
It could look like this (keep in mind that the response is measured at a distance of 2m now, not nearfield!)


This filter gives equally high efficiency as the simpler filter, but lessens the stress on the panel, as well as the trannies since its crossover-freq is higher. The panel now only works in a range where its distortion is extremly low (well below 0.1%@95dB) and You reach ear-shattering levels of SPL.
Compared to the first simpler filter the response at distance is smooother and better...You see, how important it is to get rid of the ground resonance. While the response in nearfileld looks perfect it isn´t any more on distance.
Adding to this a comparably good bass is not an easy task, but will end at a state-of-the-art speaker. I strongly recommend to use a dipole bass with such panels.

jauu
Calvin

[bear]

It might also pay to read Peter Walker's articles on ESLs - he discusses matching the panel with the transformer and its effect on freq response vs. sensitivity.

Also to review Strickland's patent on the same subject...

_-_-bear

[pmscompany]

u have a link the Peter Walker's Article ???

Originally posted by bear
It might also pay to read Peter Walker's articles on ESLs - he discusses matching the panel with the transformer and its effect on freq response vs. sensitivity.

Also to review Strickland's patent on the same subject...

_-_-bear