Ouch! that was nasty

[Westlake HR1]

Hi guys

I just purchased a used Boulder 250AE amp. It sounds fantastic. Unfortunately my spirits were dashed somewhat the first time I shut it down.

Shutdown caused a somewhat severe thump through the drivers its connected to, combined with a low to higher pitched squeal. From the initial thump to squeal is about a 3 second delay. No, there are no gain controls on the amp.

Any ideas fellas?

Ken

[edyer]

My adcom amp does the same thing. I called adcom and the tech guy said it is normal and won't hurt anything. I have used that amp on and off for four years and so far no damage to anything that I can find.

[Westlake HR1]

Although I could live with the beyond normal thump, its the squeal that bothers me. This is not normal. I have nevr had an amp do that before

Ken

[Matt Syson]

It shouldn't be normal, it sounds like poor design. Most of the worlds hifi amps Even the cheapo's can manage better.
Send it back or if it has actually developed the noise, get it fixed!
Matt S

[David Kulka]

Last week I was servicing a system with 3 Bryston 4B-ST's, and on shut down they all make freaky, disturbing sounds (not unlike what you describe) that I could only liken to Gas Music from Jupiter.

I have to agree, it does seem like bad design. If it really bugs you and if there's space inside the amp, a relay or two could be added pretty easily, to mute the speakers when power is removed.

[Westlake HR1]

Originally Posted by David Kulka

Last week I was servicing a system with 3 Bryston 4B-ST's, and on shut down they all make freaky, disturbing sounds (not unlike what you describe) that I could only liken to Gas Music from Jupiter.

I have to agree, it does seem like bad design. If it really bugs you and if there's space inside the amp, a relay or two could be added pretty easily, to mute the speakers when power is removed.

Hi David, nice to hear from you. FYI, your telescoping instructions has my system dead silent. I thank you for that. All balanced inputs have pin one dropped and I have vbeen able to eliminate 100% of the hum.

Now, back to this problem. I am sure this is a bad cap or someting in the amp. Boulder amps are not your run of the mill amplifier. These make Krells look like a bargain. They are pretty esoteric and most people have never heard of Boulder. There newer amps run in the 20 to 30,000.00 dollar range.

This will get boxed up and sent in for servicing. I unplugged the inputs and fired it up. On shutdown, it made the same noise so its not an external problem.

Ken

[Westlake HR1]

I pulled the lid and all four screws attached to the storage caps were loose. In fact, so loose they arched when the system is turned off. You would think they would have siliconed the screws after assembly so during shipment vibrations they would not work loose?

Ken