In Reply to: Soundlab is harder posted by KIS on May 4, 2012 at 21:13:29:
Ralph has given a lot of thought to this problem, and I have not. So I leave it to Ralph to comment definitively, but the SL panel is no different from any other full range ESL in that it behaves like a giant capacitor. Thus the impedance is very high at low frequencies. Parameters like mylar to stator distance, bias voltage, size of the panel, etc, all affect the "size" of the capacitative load, but this is why we need the two transformers in parallel or the SL bass transformer alone to get adequate bass response from an A1PX or the like. Direct-drive amplifiers can be designed so as to produce more "drive" or power into bass frequencies and to gradually reduce the drive as frequency increases, so as to deliver power as an inverse complement of the load presented by the speaker. I am sure this is what Acoustat did back in the day; I KNOW that is how the Beveridge dd amplifiers work. So a "crossover network" as we know it should not be necessary. However probably there is some sort of filter that must be built into the input stage. Not as damaging as a conventional speaker crossover, because very low values of capacitance could be used, therefore of very high quality. Ralph?
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Follow Ups
- RE: Soundlab is harder - Lew 22:31:32 05/04/12 (31)
- RE: Soundlab is harder - Ralph 12:20:51 05/07/12 (29)
- Dear Ralph,... - Lew 15:32:39 05/07/12 (28)
- more or less - Ralph 10:27:02 05/08/12 (27)
- RE: more or less - Lew 20:24:17 05/08/12 (25)
- You were plenty clear enough - Ralph 09:34:55 05/09/12 (24)
- This is hypothetical..., - Lew 11:07:51 05/09/12 (23)
- RE: This is hypothetical..., - Ralph 12:19:57 05/09/12 (22)
- RE: This is hypothetical..., - Lew 18:39:54 05/09/12 (21)
- RE: This is hypothetical..., - Ralph 09:17:22 05/10/12 (20)
- RE: This is hypothetical..., - KIS 15:07:20 05/10/12 (3)
- RE: This is hypothetical..., - tyu 06:11:13 05/11/12 (2)
- RE: This is hypothetical..., - Ralph 10:57:46 05/11/12 (1)
- RE: This is hypothetical..., - tyu 13:40:10 05/11/12 (0)
- RE: This is hypothetical..., - Lew 15:04:55 05/10/12 (15)
- balanced input on that would be easy. nt - Ralph 20:03:24 05/10/12 (13)
- RE: balanced input on that would be easy. nt - Lew 16:28:10 05/11/12 (12)
- can we get just a tad more to the left in that photo? nt - Ralph 12:14:30 05/15/12 (8)
- Here you go... - Lew 19:24:52 05/15/12 (7)
- much better - Lew 19:37:51 05/15/12 (6)
- And more better - Lew 19:38:52 05/15/12 (5)
- RE: And more better - Ralph 08:31:56 05/16/12 (4)
- RE: And more better - Lew 11:43:56 05/16/12 (3)
- RE: And more better - Ralph 12:22:07 05/16/12 (2)
- Designer = Roger Modjeski - Lew 12:40:33 05/16/12 (1)
- RE: Designer = Roger Modjeski - tyu 05:23:09 06/11/12 (0)
- RE: balanced input on that would be easy. nt - tyu 07:58:37 05/12/12 (2)
- RE: balanced input on that would be easy. nt - Lew 10:26:41 05/12/12 (1)
- RE: balanced input on that would be easy. nt - tyu 11:58:08 05/12/12 (0)
- RE: This is hypothetical..., - KIS 15:46:56 05/10/12 (0)
- Used to work with old TVs back in the early eighties... - Penguin 17:20:27 05/08/12 (0)
- If Ralph Builds One, I am on the queue nt - KIS 23:36:55 05/04/12 (0)