ESLs used >150 Hz (ie Active subs) - amp . .

[otto88]

Below c 150 Hz, I'll be using ESLs with the active servo controlled 2 * 30 cm a side dipole woofers:

http://www.gr-research.com/index.as...PROD&ProdID=140

http://www.audiocircle.com/index.php?topic=54875.0

If eg a SE tube amp used were that way with normal cone mid-bass drivers, the demands on the often "weakest link" in the amp, the SE's output transformers, would be significantly reduced.

If ESLs are used above say 150 Hz, does that make any difference to the demands - requirements on a SS amp?

Thanks

[otto88]

Just wishful thinking?

I imagine that it depends on what part of the FR of an ESL places most demands on the amp.

For ESLs, is it posssible to usefully generalze at all about that?

Thanks

[Calvin]

Hi,

of course it does. It´s always positive to reduce the currents in the transformer and since the larger currents are required in the low frequency departement, highpass-filtering improves the situation and allows for much higher output levels.

jauu
Calvin

[Brett]

Aren't most ES speakers fairly inefficient anyway? You'll relieve the amp of trying to drive the LF content, but will you have enough power?

[otto88]

highpass-filtering improves the situation and allows for much higher output levels

Thanks Calvin, but rather than the effect on *output levels, I was asking if:

a pair of ESLs when run full range need an amplifier with - for example - a nominal spec of
- 150 watts into 4 ohms,
- stable into 2 ohms and
- current capability of 10 A

When run only above say 150 Hz, what (nominal) amp specs might change?

Cheers

[Calvin]

Hi,

what is needed depends on the impedance of the ESL. Typically a pure ESL-audio-tranny combination shows an impedance plot looking similar to a gaussian curve. So You can expect a rising value with a maximum in the low hundreds of Hz and a falling response up to 10KHz-20kHz. But this can change remarkably when the panel is of segmented type, special audio-tranny configurations are used (think of Acoustat or Audiostatic) and/or corrective crossover parts are used.

@Brett: Only the coupling of the ESL through the transformer makes it inefficient. The panel itself can be highly efficient (up to 30% efficiency is reported... much more than the ~1-3% of the typical dynamic speaker). But transformer coupling is unfortunately the usual way to drive the ESL.

jau
Calvin

[Andersonix]

Originally posted by otto88
When run only above say 150 Hz, what (nominal) amp specs might change?

Does this ESP bi-amping article help?

[otto88]

Thanks Tosh, I'm aware of the benefits of bi-amping normal active speakers, but think ESLs *could be quite different.
Though I don't know:

Calvin, I will try to find out if my ESLs (Moss) are of the "segmented type" (right n they are at my my ex-wife's house )

Though if the part of the FR that is being removed is "the bottom 3 octaves (20 - 160 Hz), where ESL impedance is near its maximum, and required excursion is at its maximum, can anything be said?

Thanks

[otto88]

I should have said:

can anything be said, in particular about the required current.

ie might the need for amp current be (**rule of thumb**) reduced by . . 20 - 50%, to . . . ??

Thanks