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Power-up sequence with valves and ESLs?

Mike Reed

Mike Reed

pfm Member
When one of my EAR power amps blew a fuse last year, the resulting noise from my 2905 Quads was alarming. Maybe just me, as they were fine afterwards, but worrying nonetheless. As I'm wary of a similar circumstance, and always fire up my ESLs a fair time before firing up the amps, I wonder if I need to have a speaker load when turning on the power.

I accidentally did this once (when I forgot to fire up the speakers) and there was no problem. Oddly, as I understood that ESLs needed some time to come to life, I didn't notice any s.q. deterioration at that time.

Is there a fundamental difference in load requirements in valve powr amps between m/coil and ESLs which are off? Also, would I get a thump or whatever by turning ESLs on last (if viable)?
 
It will be fine to switch ESL's on last but with ESL's in general many reckon they need some time to reach best performance after switch on.... This will vary massively depending on all sorts of factors such as humidity and condition of panels and may in fact be a non issue with the most modern ESL's such as yours.
 
Source, pre, powers, quads always. Depending on age, temp humidity and usage quads take a while to reach full charge. Any more than a few minutes and they likely need a service. A modern pair should be less temperamental, my 63s take about five minutes to settle.
 
During the course of the last 15 years or so I’ve used 57s 63s 989s and 2905s and other than when going away for holidays I didn’t switch them off at all and had no particular issues that I can recall.

Anyway Mike I’m sure you’ve considered leaving them on but perhaps have an aversion to this as an option.

Cheers,

Dave
 
DAVEDWACK said:
Anyway Mike I’m sure you’ve considered leaving them on but perhaps have an aversion to this as an option.
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I've read this about older Quads, but seriously, I don't use them enough in a week (or even fortnight) nowadays to justify or warrant their being on 24/7. Also, I cover them with sheets (though that's unlikely to make a difference, I s'pose) Besides, advice above suggests switch ESLs on last and 24/7 wouldn't follow this.

Thanks for the advice and assurances, Jez and Simon. The 15 minutes or so for the 509s' LEDs to fully stabilise should be more than adequate for ESL warm-up, I'd think, so shall follow this course. I had a vague feeling that s/s and valved amps were different in respect to whether they should see a load when switched on but maybe these examples were oddities or I was simply mistaken.
 
Completely cold ESLs will still provide an amplifier load, but bad things could happen to amp and/or speaker if you put some music on and turned it right up.

I think Quads ESL63 on are more or less 'instant on' but the 57 can take a bit longer. Quad used to recommend connecting them to the power outlets on a 22 preamp, so when power was applied the speakers could charge while the valves warmed up. This gives an idea of how long the manufacturer considered necessary... Old or rebuilt speakers may of course react more slowly. There's no downside to leaving them on semi-permanently, the power consumption (especially for originals) is effectively zero.
 
Never had an issue and they are always turned on all the time. They use tiny amounts of electricity, so no saving as such by turning them off. Certainly older panels can take a while to charge.
 
Paul R said:
Completely cold ESLs will still provide an amplifier load, but bad things could happen to amp and/or speaker if you put some music on and turned it right up.
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Interesting, Paul, so un-energised panels still represent a load. Re. your second mention, which is new to me, my amps' input controls are in the off position until ready to use and my pre. is always on an unused source and has lowest pot. point, although generally, sources are fired up afterwards when I decide what to listen to (4 sources). Hence little chance of that happening, not that I'd ever thought about it !;)
 
I'm not sure if the amp can even tell if the panels are charged, current doesn't flow on and off the diaphragm. But it will always see the capacitance between the stators and the transformer(s) winding(s). So load should be constant, if your amps care about it.

With old Quad speakers you need to have an awareness of 'normal' volume control levels, so that if the EHT supplies start to fail or the panel otherwise loses some sensitivity you don't end up simply turning it up. This is how many tweeter panels get damaged. It writes like it's complicated, but really just the audio equivalent of mechanical sympathy when driving a car.
 
FWIW I always turn on my ESLs first thing in the morning and leave them powered all day. They take a few mins to settle I assume, but the charge will then linger for a while. Done this from 57's onward as SOP.

We did once come home to a could house after being away for a week and I powered up the amps, etc, and tried some music - having forgotten to power the ESLs. I did hear music, but realised it was quite faint. Then twigged my "oops!" and switched on the ESL power and the volume quickly increased to normal.

So far as I can tell it makes little differene in 'speaker/amp damage' terms. UNLESS you wind up the audio because it "isn't loud enough" and then prompt a problem. The speaker efficiency is low, and the network loading probably doesn't vary a lot when the moving sheet is/isn't polarised. So I'd say the only concern is not to accidentally wind up the power because you forgot to energise the panels.

Hence for decades I just power the speakers when I get up in the mornings.
 
Forty odd years ago when we had an ESL57 driven by a JLH class A they were both switched on and of simultaneously, purely as a matter of convenience. It never occurred to me that the loading would significantly alter with the ESL on or off and anyway the JLH didn`t care.
 
chartz said:
My ESLs are always on. Problem solved.
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Not my problem, though, where I want to avoid any nasties if an amp fuse blows again. Just a wee bit paranoid after that episode a year plus ago, though the amps have been fine since. First mains fuse blow in a power amp (or integrated if my memory serves) in 50+ years of owning them. I did learn about slow-blow and fast-blow fuses though, esp. where valve amps are concerned :rolleyes:
 
Remember that you have two transformers between the power valves and the electrostatic panel. Not much of a risk there.
 
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