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In Reply to: RE: Foreplay damaging my speakers?!!! posted by b. on June 29, 2009 at 08:57:52
Just tried to measure at the F5's binding post (with speakers disconnected). After about 10 seconds it peaks at -15V when I switch it off and -12V when I switch it on, or vice versa. It too late at night here now for me to put on any music to see if my speakers are ok, so will go to sleep now having nightmares of cooked drivers. Tonight may have been the first time I switched off the Bottlehead before the F5 so I could well have really done it this time :(
If there is DC at the output of the Foreplay, then it certainly has a problem. With tube gear, you always want to turn the amp on last to avoid hearing any of the startup noises. The FP-III without the extended upgrade makes quite the peculiar startup noise (harmless though).
typically we turn on phono and preamps at least 10 -15 seconds before power amps to let the caps charge up and everything start working. follow the same sequence when shutting down- power amps off first, then a few seconds later, the pre's. How does it sound?
Thanks for the replies.
Having first listen now, sounds ok. I mean as in no damage. The F5 with Foreplay sounds very good though, prefer it to the F5 with passive TVC and to the F3 with TVC.
And many have posted the same post. Once you get the rule of power amp on last and off first with a 15s delay nothing happens.
But the thumps are rude and exciting. I don't know of anyone who has damaged a speaker. But it makes you jump, doesn't it!
Remember, YOU are the only one who needs to be happy with the sound of your system
Grainger Morrison
There Is Only One (Grainger Morrison, it seems)
Allow me to stand forth and be counted. One week when my Paramours were offline for an upgrade, I put a 150-watt SS amp into the system with a Foreplay (1) and a pair of single-driver speakers (Buschhorns with Radio Shack 4" drivers). For whatever reason, one day, I flipped on the power switch for the amp and the pre-amp at the same time. With the Paramours, that indiscretion would have led to a mild thump as described. With the SS amp, it made no noise at all. But it "let the magic smoke out" of the drivers, fusing the voice coils.
Tell you what, I haven't made that mistake since.
An Eagle 2C. Took out my Dynaudio Woofers. A really expensive mistake. But it was a power outage (power up actually) that took them out when I wasn't at home.
Remember, YOU are the only one who needs to be happy with the sound of your system
Grainger Morrison
There Is Only One (Grainger Morrison, it seems)
Thanks guys.
Grainger, seems this is a different problem perhaps as it makes no sound at all, just a slow silent move of the driver to xmax over the course of a few seconds.
I have seen that before too. Sounds like a leaking capacitor. IIRC, you said that your amp doesn't have any audio path capacitors. That puts it in the preamp.But does it do this if you follow the turn on routine? If it does there is something wrong. And if it is a leaking cap it would probably do the same thing again after turn on.
Is it just a turn on problem or is is recurring after turn on?
Remember, YOU are the only one who needs to be happy with the sound of your system
Grainger Morrison
There Is Only One (Grainger Morrison, it seems)
Edits: 07/01/09
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