Help needed with a diy hybrid esl

[badduh]

I'm planning to build a pair of hybrid esl's, de bass going to be a 12" dipole woofer per side. The esl is propably going to be a panel of 20 cm width and 50 cm height, with stators made of wire. As a step up tranformer i want to use a pair of standard 220v/6v transformers per side, are http://www.ratoshop.be/transformatoren/ringkern/100000979c0c62825.html]this[/URL] transformer capable of doing the job? the site is in dutch but i think/hope you understand the specs.

(Sorry for writing english the wrong way, i have no problems to read is but writing it is an other thing )

[badduh]

Sorry i have done something wrong, the correct url should be:

http://www.ratoshop.be/transformator...9c0c62825.html

[maudio]

If they are any good for audio is difficult to tell, you have to get one and measure it.

I fear a 15VA model is not terrible large, I would consider switching to a larger model. Depends on crossover freq, but with a 12" sub I suppose you want to crossover below 150hz?

You might want to consider a higher panel, will give you more output and better imaging (line source).

Btw what woofer do you plan to use for the dipole?

[badduh]

Thanks for your answer Maudio, the problem is that i don't have the equipment to measure the transformers, how large do you thinks the transformers should be? 30/50Va?
I don't know yet how low a want to set the crossover, i want to build a measurement microphone first so i can measure the frequence response of the woofers.
I have a couple of units who are produced with different names like skytronix and xxl, the are not verry expensive but, the are made of aluminium, have a fs of 23 hz and produce 97db/w
Some specs:

Référence : PAW 305
Diamètre ext : 310 mm
Bande passante : 20 - 2000 Hz
Puissance maxi RMS : 450 W/215 W
Sensibilité : 97 dB
Fréquence de résonance : 23 Hz
Impédance : 8 ?
Poids : 4850 g



Normally i would not buy speakers of this brand but because dipole woofers are not that critic, i like to give them a try.

[BillH]

Hi, badduh.

how large do you thinks the transformers should be?

I_Forgot talks about toroid transformers in this post. He feels 30VA should be fine.

I don't know yet how low a want to set the crossover

There's a lot of variables in ESL building, so you'll probably have to build your ESLs and measure their low end cutoff to find your initial crossover frequency. Then listen and adjust the crossover as needed to blend in with the woofers. A computer and soundcard with crossover software will make this quite easy.

I agree with maudio about the size of the ESL, bigger is better.

[I_Forgot]

Originally posted by BillH

I_Forgot talks about toroid transformers in this post. He feels 30VA should be fine.

I should make it clear that I have not yet tried the power transformer trick. My speculation that 30W transformers should be adequate is based on using one or two 30W audio output transformers per speaker and finding them adequate. There are others lurking about this forum who have used power transformers in lieu of audio output transformers and can tell you their actual experience.

Power transformer ratings are based in part on the frequency of operation and the size of the core. They are almost always spec'd at 50 or 60 Hz. Audio transformer power ratings are based on the same things, but thanks to the marketing guys, their power ratings may be quoted at different frequencies. Based on this, a 30VA power transformer should be good for 30W of audio at 50-60Hz. An ESL won't use the 30W, even when playing loudly while driven by a 200W amplifier.

I will always recommend using two transformers per speaker when the builder's economic situation allows it. Power transformers are so cheap there is no reason not to use two of them per speaker.

I_F

[maudio]

Not every woofer can be used in dipole. Important is Fs, Qts and Xmax. The driver should also be free from noise when driven to large excursions in free air. Have a look at this thread

[badduh]

@maudio. I become interested in dipole woofers bij this My first Dipole Subwoofer!!! thread, the conclusion of the topic was that woofers witch normally would sound horrible in a monopole setup could sound suprisenly good in a dipole setup. I had the uppertunity to buy a pair of the xxl paw-305 woofers for 40 euro, i think i can't go wrong for that. But as i mentioned before i have to measure them first, to see what they're capable of.

@iforgot Do you think it is posible to use 15Va transformers? The 30Va type is significant more expensive than the 15 Va type. On the other hand, if you think that the minimum is 30 Va i could also buy the 50 Va type because the price difference between 30 and 50 Va is only 0,5 euro. Do i understand you correctly if i say that the higher the crossover, the lower the Va has to be?

[I_Forgot]

Originally posted by badduh

@iforgot Do you think it is posible to use 15Va transformers? The 30Va type is significant more expensive than the 15 Va type. On the other hand, if you think that the minimum is 30 Va i could also buy the 50 Va type because the price difference between 30 and 50 Va is only 0,5 euro. Do i understand you correctly if i say that the higher the crossover, the lower the Va has to be?

I hope you're not buying the transformers new... If you look at some surplus dealers you can usually find transformers in the 15-50VA range for $5-10 each. If you can't find cheap 30-50VA transformers, keep looking- they are out there.

15VA will work, but may not work well when you try to play at loud volumes. OTOH, if you're crossing over so the low frequencies never go to the ESLs, 15VA may be fine. If they are cheap, try them and let us know if they work.

I_F

[badduh]

I have searched the internet but i haven't found them second hand in europe. I also didn't vind the somewhere cheaper than the shop mentioned in my first post, The 15 Va ampere costs 13,50 euro incl. vat, i don't think that i wil find them anywhere cheaper in europe.

A have made al litle design for the speaker, i want to make something that looks like this: