On 8/12/2020 12:39 pm, Phil Allison wrote:
Trevor Wilson Bull****ted:
======================


**I have some familiarity with a few Acoustat models. I am unaware of
any that came with inbuilt power amps, though I guess it is possible
that one or two were.

** The modlel " X " IIRC.

Direct drive form the tubes runnint at 5kV.

****** me. I think you're correct. Direct drive ESLs - the Holy Grail.
Very rare. Never seen one. I've worked on 2+2, 1+1 and Spectra models
(the impedance curve was a Spectra).



I can tell you that the load presented by most
Acoustats is brutal. Only amplifiers capable of substantial current
ability and unconditional stability should be used. Here is an impedance
graph I ran on an old Acoustat amny years ago:

https://www.rageaudio.com.au/index.php?p=1_12

Check out the dip at 15kHz.


** Very easy load for any sanely built amp.

Trouble for your nutty MEs - were they ??


**The ME850, with zero global NFB, a 2.5kVA power transformer, 245,000uF
and 70 Amps of continuous (till the mains fuse fails) current capacity?
None at all. Perfectly stable, regardless of load. A perfect match for
any ESL (or any other speaker, in fact). The ME1400 would do even
better, without raising a sweat (5kVA power transformer, 310,000uF and
100 Amps).

Nutty? Maybe, in this era of pretty impressive Class D amps. Still,
people like 'em. I know I do.


--
Trevor Wilson
www.rageaudio.com.au

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