Session 400 Power-up

Roger Andrusky · Post by **Roger Andrusky** » 25 Nov 2001 9:34 am

I have a '77 vintage Session 400 which has served me well, but I was wondering if anyone was ever concerned about the 50 Volts of DC the speaker has to absorb when the amp is turned on. I installed a relay with a time delay which allows the poer supply to to come up before the speaker is put on-line. I put a dummy load accross the amp output until the power supply is ready.

Has anyone else done anything similar?

Larry Bell · Post by **Larry Bell** » 25 Nov 2001 10:34 am

I used to turn the pre-gain all the way down before turning my mid-70s Session 4 off, thinking that the THUD would damage the speaker when I turned it back on. I don't do that any longer and, after almost 25 years, I've only replaced the speaker once.

About 3 years ago I put the head and reverb tank in a separate cabinet and now use it with two 115e cabinets -- still haven't noticed any ill effects.

Your mileage may vary, of course.

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<small>Larry Bell - email: larry@larrybell.org - gigs - Home Page
2000 Fessenden S-12 8x8, 1969 Emmons S-12 6x6, 1971 Emmons D-10 9x9, 1971 Dobro

Jack Stoner · Post by **Jack Stoner** » 25 Nov 2001 11:24 am

The power on voltage "pop" does not to appear to be a problem on the Peavey amps. According to Mike Brown, at Peavey, the power on (and power off) "pop" cause by the instant voltage is normal.

However, my MosValve 500 power amp does not do it as there is a relay built in.

I've worked on Peavey amps that had blown speakers but it was (apparently) caused by the fact the power amp section had blown components.

Bob Carlson · Post by **Bob Carlson** » 25 Nov 2001 9:21 pm

Jack, I've been going to ask if that pop was normal when I turn it on with nothing but my steel pluged in and vol pedal back. But you've answered my question. Thanks.

BC

Mike Brown · Post by **Mike Brown** » 27 Nov 2001 11:10 am

I checked with our repair techs here at the factory and a speaker has never failed in a Peavey amp due to turn on/off transient. You will hear a "pop" on most of the amps, but this is normal. A relay does help eliminate this "pop", but there is not a need to modify a Peavey amp for this.

Over time, capacitors can become leaky. This can happen with any brand of product. A basic "rule of thumb" that we use is if the speaker moves inward or outward when the amp is turned on, we check the filter capacitors for leakage and replace as necessary.