On 8/12/2020 4:06 pm, Phil Allison wrote:
Trevor Wilson wrote:
-------------------------------

** You omitted the *very real* risk of damaging the input power limiter of a Quad ESL63 and any of its relatives.


**Both amps would certainly fry the TRIAC(?), if pushed. If I recall
correctly, the ME850 (maximum output Voltage = 31 VRMS) would not exceed
the maximum Voltage limits of the ESL63? The ME1400 certainly would (42
VRMS). Overkill for the ESL63.


** The ESL63 has two input limiting triggers.

1. A voltage peak value of about 35V using a power transistor or zener array.

2. A simple ionisation detector ( uses a 555 ) trips a triac for a short time.

It's often a 1.5ohm, 5W resistor in series with the speaker that can pop.
Later marks have a fuse to save it.
In any case Quad, warns not to use amps have no VI limiting with their ESLs.

**An ME550-II then. MUCH more polite. 27 VRMS, 500VA transformer,
120,000uF and 40 Amps of PEAK current. Easier to freight too. Only 16kg.
All ME amps are current limited.

Peter Stein learned to his cost, way back in the late 1970s, that
pathological speakers loads, like the Infinity RS4.5 would kill a 38
VRMS amp, with around 70 Amps of current ability, but without current
limiting. The design genius' at Infinity, decided that it was a good
idea to place 2 X 4 Ohm bass drivers in parallel was a good idea.
Trouble was, the bass drivers also had a 2 Ohm voice coil, which was
paralleled with the 4 Ohm voice coils at LF. The importer smoked several
Phase Linear amps, a bunch of Yamahas and several others, before trying
the ME. It last 6 weeks, then died horribly. Output stage SOA was
exceeded. Peter began fitting current limiters to all subsequent amps.


--
Trevor Wilson
www.rageaudio.com.au

--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus