Is it normal for the woofer to move in/out slowly

My only tubed piece is the pre-amp. It is the only piece I turn off when not in use. I noticed that when I turn it off the woofers on my speakers move in and out rather slowly while I hear what I assume are the tubes discharging.

Is that normal and more importantly can it cause damage to the speakers?


What you are describing happens to my woofers when I turn my power amp ON. I don't have any tubed gear though, so it may not be a good comparison. I'm not an expert, but I don't think this would cause damage unless it happened for an extended period of time (i.e. overheat voice coil?). Maybe someone else can correct/confirm that.
On your pre amp do you have a mute switch;if so I would mute first and then power off to see if it happens.
Do your amp(s) have a standby switch? It seems to me that you are seeing the affects of the pre amp tubes bleeding down and the power amp(s) is passing that affect to the woofer.As far a damage I would not think that would cause any.
IMO it is asking for trouble turning off a pre amp while the amps are on. Why do you turn it off? Maybe I am old school, but I have always left my pre amps on.
4est, he turns the pre only off because it is a TUBE unit. Tubes wear out just being left on. SS does not
Well, some Tube preamp manufactures recommend them turned on all the time, I've had mine on for over 2 years with original tubes...
1. It's not abnormal

2. It's only bad if it drives the woofers to their mechanical limits.

If you really wanted you could hang a scope on your speaker terminals and see what's happening.

1-1.5 volts peak is fine even for tweeters (That's what I get in the power amp connected directly to my main actively tri-amplified system's tweeters and they have over a thousand power cycles on them).
Bokfudo, My speakers does this. I have a tube pre which I turn off after listening, have done this for years with no issues. Back to your question, yes my speakers does this and I don't see it as a problem hence have not investigated. But I will not worry about it.
It sounds like it is OK since the woofers are not driven to their limit and they move slowly. I wish I could leave the tubed pre on all the time but like a light bulb, that would reduce the life of the tubes.

Thanks for the answers!
Here's a question I have concerning this. What would damage the tubes more, surge from turning pre-amp on and off repeatedly or leaving pre-amp on most of the time?
Rja, thats a good question. Have no answer, however, there have been several discussions about if leaving the pre on is better than off. Based on my point of view most don't know the answer and some will offer some elaborate technical reason one way or other, its all pure speculation. Like I said I turn my on and off between listening sessions and have been doing this for years with no negative effect. I have used the same set of 6sn7 tubes over the years.
Rja also brings up a good point, repeated surges from frequent turning on I guess will affect tube life as well. May be the best compromise is to turn the pre on once a day and off for bed time :-)

I don't think it would do any harm to the woofers.

My practice is that I always turn the pre amp on first and then the power amps. When turning them off, I turn the amps off first and then the pre amp. That way, nothing affects the woofers.

I learned a lesson a few years ago. I got a tube pre and a SS amps. When I turned off the pre amp first, a surge went to the amps and blew the fuse and some other things in the input stage. I ended up sending the amps back to the factory to repair.
This happens when I turn my Exposure 2010s2 integrated OFF. A few seconds after I hit the button I see the woofers move in then out with a kind of sucking noise at the same time. When powering on this does not happen. The 2010s2 has no tubes, it's a solid state amp. I always assumed this was not harmful.