Speaker Protection Question.

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** That post was from *me* you dopey retard !!!

And I *deliberately* did NOT refer to the idea of using a film cap.

Cos it is NOT a good one for the actual purpose.

See my reply for the reason.

FYI:

Appear on SER and I will murder you.

..... Phil

I know that Phil, I'm not drunk. However it was Chris who posted it here after you didn't reply to his question on the subject a week ago.

If you'd said that a week ago when Chris first reffered to the post it would have saved him a bunch of time tracking it down

I saw it and read it. Your reply doesn't change the fact that Chris went out of his way to find it for me after you didn't reply to his question about it.

Just because it's evening and you're pissed and alone again there's no need to try to take it out on me.

I think I'll wander over to s.e.r, introduce myself and tell them that I'm there because of you.

As for "I will murder you" all I can say is wow! How brave of you, making threats safe behind your keyboard. What a man!! A drunk and lonely man but you sure seem to think that you're tough.

Perhaps maybe stick to something you might have a chance of doing - like murdering another beer.

--
Shaun. 

"Humans will have advanced a long, long way when religious belief has a cozy  
little classification in the DSM*." 
David Melville (in r.a.s.f1) 
(*Diagnostic and Statistical Manual of Mental Disorders)

Yes, though in the present situation with no speaker protection at all, it is just as bad, and adding the relay with capacitor might help the speaker to survive an amplifier failure without burning out. Perhaps this particular amplifier does not suffer from those switch on noises anyway, e.g. due to lucky supply sequencing.

If the relay has two sets of contacts that are able to be connected in series, then a capacitor could be connected across just one set of contacts. The contacts with the capacitor would be able to switch off the speaker hopefully without arcing in the event of an amplifier fault, and the contacts with no capacitor would stop the clicks and pops if they occur when the relay coil is not energised.

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** Using a DPDT relay wired like I suggested works a treat - and is totally silent when in the rest position.

It's the only method that deserves recommendation.

** When connected to a pre-amp, if both come on from the same AC switch - it almost certain to make a loud noise. ** Tolerating one iffy relay contact in series with Hi-Fi speaker is bad enough thank you.

.... Phil

Once upon a time on usenet ~misfit~ wrote: [snipped]

Well I finally got a transformer (EI as I didn't think a toroidal was needed as the 'signal' is high-current) and built two of these single channel protection PCBs into a re-puposed case. I figurd they're better than nothing (if only for the built-in 3 second delay to avoid 'thump') until I can rebuild a different two-channel upc1237 based PCB with remote relays to short the speakers...

The damn thing introduces shitloads of hum! It took me a while to make back and front panels for the case so only just got around to hooking it up with my existing amps. (I prioritised this over finishing the refurb of the other amp so I'd have /some/ protection ready and could use it when finished.) I tried removing the transformer and running it oiutside the case but it still hums.

Biugger! I don't get much low-pain 'mobile' time as it is after the housework etc is done and I've just wasted a bunch building this thing. Who'd have thought these would introduce so much hum? (Not me obviously.) It's not as if I've got my stereo system laid out as I'd like it yet with speaker wires and power cables separated AMAP and only crossing at right-angles (I'm planning on putting it in a different place when it's all done so...).

--
Shaun. 

"Humans will have advanced a long, long way when religious belief has a cozy  
little classification in the DSM*." 
David Melville (in r.a.s.f1) 
(*Diagnostic and Statistical Manual of Mental Disorders)

Thanks. It is. In both the amplifiers and the speaker protection unit. (Although the amp I'm rewiring curently to use soon, the Playmaster Pro III doesn't isolate the mains and speaker earths.)

--
Shaun. 

"Humans will have advanced a long, long way when religious belief has a cozy  
little classification in the DSM*." 
David Melville (in r.a.s.f1) 
(*Diagnostic and Statistical Manual of Mental Disorders)

-------------------

** That is not what TW meant.

He was saying not to create and EXTRA mains earth going to the speaker ground terminals - cos doing that can make a "hum loop".

..... Phil

Cheers,

--
Shaun. 

"Humans will have advanced a long, long way when religious belief has a cozy  
little classification in the DSM*." 
David Melville (in r.a.s.f1) 
(*Diagnostic and Statistical Manual of Mental Disorders)

HI ~misfit~ I came across this thread in search for any information on the eht systems, I have 4x of the eht4000 amps an trying to find a path to the user manual. or even specs on the pmh3 and pmh2 speaker boxes. Do you have any leads online?

also built a playmaster pro3 in year 10 for my major electronics project, it is still alive and kicking nearly 14 years later!

Hi Aaron.

Sorry I have no leads to give you but others here might. I've tweaked the Playmaster Pro3, rewired the power supply, replaced the capacitors etc but I'm still not happy with the sound so the case / heatsinks / toroids are going to be used for another project I have going - one using K135 / J50s.

Good luck with your search.

--
Shaun. 

"Humans will have advanced a long, long way when religious belief has a cozy  
little classification in the DSM*." 
David Melville (in r.a.s.f1) 
(*Diagnostic and Statistical Manual of Mental Disorders)