Dear Luther,
The mod to alter or remove protection devices remains a catch-22
situation. In other words, MOST amps do not have enough output devices
or enough heat sink area to absorb the extra dissipation of the output
devices hence, the need for protection circuits. The situation will have
to be assessed on an individual basis. It's really very simple: either
there are enough devices and heat sink area to handle a +J90 to -J90
load or there isn't. Of course this also depends upon the kind of music
one listens to and how loud one listens as well as what kind of speakers
one has. Even though electrostatics are generally more difficult to
drive, they also have some limitations in the area of voltage
limitations, especially at low frequencies where severe arcing can
occur. For example, the old original Quad electrostatics could not stand
more than 25 volts RMS which is around 70 watts. Any more would surely
wipe them out. The newer ELS-63's on the other hand could be driven by a
200 watt amp but since the design ended up being constantly
pseudo-resonated over the frequency band, the speakers were relatively
easy to drive.
Therefore, anyone wishing to change the protection circuits in an
amplifier MUST consider all of the ramifications before attempting any
alterations.
James Bongiorno
Wardsweb wrote:
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From: "Wardsweb" <wardsweb@...>
JB - thanks for the insight. As far as type, will this work with the
later Computer Direct-Line? The only other amp I have is a 3100, but
mainly I use A501 and A502's. I would definitly look into this, if it
would work for an A1001. Luther
----- Original Message -----
From: sstinc: First sstinc:Last
To: SAE_Talk@...
Sent: Sunday, January 30, 2000 1:26 AM
Subject: Re: [SAE_Talk] SAE Owner's Showcase
Dear Luther,
Depending on what SAE amps you have, they certainly can be
adjusted to drive electrostatics. When I worked there,
Morris was OVERLY concerned about protection circuits mainly
because he didn't at that time understand the true nature of
VA loadlines. Most engineers STILL don't understand the
situation. A properly designed amplifier should be perfectly
capable of driving any rated VA into a load in ALL FOUR
QUADRANTS. However, this ends up being a true enigma because
in order to protect against a true short circuit, volt-amp
limiting must be used. You can modify or remove the limiters
with no adverse effects AS LONG as you don't short the
outputs. 2 ohm reactive loads should not be a problem
assuming that the music you listen to has a reasonable
dynamic range.
If anyone wants to delve into this situation I'll be happy
to discuss this situation further.
James Bongiorno
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