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External speaker protection units

GruntPuppy

pfm Member
I've only just found out that these are a thing, and they're a thing that could solve a problem for me - the Adcom Thump on turn-on is typically outside the frequency range that my speakers can safely reproduce. Having come so close to getting this system finished, I'm too close to take chances with the speakers now.

So do any of you have any experience of a unit that you could recommend?
 
My older Exposure power amps all thump on switch on. Done so for many years. Dont think its a problem. See what Adcom say ?
 
The simplest solution is a speaker switch. Power up the system then switch the speakers in and vice versa.

Cheers,

DV
 
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I'm pretty sure the Velleman unit is a kit only.

Protection against "going DC" is infinitely more important than harmless switch on thumps!

As an external unit the issue is that it then needs to be built into a suitable case with connectors, mains lead etc etc
 
If you make sure to turn the volume down before turning the amplifier on or off, this will not damage 99% of the speakers connected to it.
 
Gervais, the problem is not with the pre-amp, it's with my power amps - that have no speaker protection. Being adcoms they thump at startup and shutdown. Turning the volume on the preamp down doesn't change this.
 
Not sure if you can get complete units, but with a bit of DIY:
http://www.velleman.co.uk/contents/en-uk/p240.html

Or search Ebay for the UPC1237 units.

WRT the Adcom. Does it cause your speaker cones to bottom out? If not, then it will not do any harm. Unless you have very delicate voice coils!

I have no DIY skills, sadly, so it's an external module I shall need.

My worry is that during startup and shutdown the amps (particularly the main freqs amp) produces frequencies outside those the speakers can safely handle; specifically, the 80hz down frequencies which they were not designed to reproduce.
 
What's wrong with doing what DV suggested? A simple speaker switch can let you connect the speakers after switchon.

That said, simply saying your speakers aren't designed to *reproduce* below 80Hz doesn't automatically mean a switch-on thump is a problem. I've used 200wpc amps with ESLs for decades. They thump, but it doesn't bother the speakers.

And if by any chance your amps have output caps (i.e. ac coupled) a switch won't help. May even make things worse!

Its the *size* a thump that may matter, not the 'frequency'.
 
It's not a problem unless you are using active speakers with the drive units directly connected to the amplifiers but the tweeters would likely have been destroyed the first time you switched it on. For normal full range speakers it is not an issue.

There seems to be no commercially available units which are suitable.
 
My older Exposure power amps all thump on switch on. Done so for many years. Dont think its a problem. See what Adcom say ?

It's not a problem - adcom deliberately don't (or didn't) fit speaker protection, their viewpoint is that it was an unnecessary complication to the signal path, for the most part. My problem is my prima donna speakers.

I've spoken to a lot of people who've run Snell Ref A5 setups (mainly in the US), a lot of them have had failure due to amp issues, I'm keen to avoid this. Particularly with the way Adcoms behave at power on and off. - thumps and squeaks, anyone?

I've got to send a faulty GFA585LE off for repair in the near future, I'm hoping it's possible to get a speaker protection module fitted then to give me some peace of mind.
 
It's not a problem unless you are using active speakers with the drive units directly connected to the amplifiers but the tweeters would likely have been destroyed the first time you switched it on. For normal full range speakers it is not an issue.

There seems to be no commercially available units which are suitable.

I don't have full range speakers, Jez. the amp I particularly worry about is connected to Snell ref a5 towers - which only go from 80hz up (my pre-amp splits frequencies below this to a second stereo power amp, and thence to the subs) . My thump-on, thump off adcoms thump and squeak below this... I think I've got a repairer lined up, but their personal circumstances are a bit variable. Should they not be available, would you be willing and able to take on the repair of a motorboating GFA685LE, and the supply and fit of a suitable speaker protection module (and possibly also retrofit an IEC socket instead of a captive cable)?
 
If your speakers aren't designed to cope with frequencies below 80Hz then why haven't they shat themselves yet with normal music? Or are you using a high-pass filter to protect them from sub-80Hz frequencies?

EDIT - Never mind, I hadn't seen your last post where you say they are high-passed.
 
I don't have full range speakers, Jez. the amp I particularly worry about is connected to Snell ref a5 towers - which only go from 80hz up (my pre-amp splits frequencies below this to a second stereo power amp, and thence to the subs) . My thump-on, thump off adcoms thump and squeak below this... I think I've got a repairer lined up, but their personal circumstances are a bit variable. Should they not be available, would you be willing and able to take on the repair of a motorboating GFA685LE, and the supply and fit of a suitable speaker protection module (and possibly also retrofit an IEC socket instead of a captive cable)?

That should be fine as it is then.

I've got much too much on at the moment to take that on and would anyway refuse to change a captive lead for an IEC socket on principal.
 
Nope, it's a straight question as to why you wouldn't fit an IEC socket in place of the captive power lead. If there's a simple answer as to why not, it eludes me.

OK... for the same reason that a reputable builder would turn down the job of building a unicorn enclosure!
 
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