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Are my speakers supposed to do this?

Hi all. Thanks for reading this thread. I just put a new preamp (Eastern Electric Minimax) into my system and am noticing some weirdness in my speakers. When everything is on but no music is playing I noticed that both the left and right drivers of my monitors (Tyler Acoustic taylos) are moving forward and backwards very slowly but at a very steady rhythm. Takes about a second for them to move forward and then another second to move back. They repeat this cycle until I turn the amp off. This doesn't seem normal to me. I never noticed this with my previous pre. When I play music through the system it seems okay, no obvious distortion although I do notice my drivers moving (from my listening position 7 feet away) in a similar way - slow in and out although it doesn't seem as cyclical.

When I first put the Minimax preamp into my system there was a very loud hum and some static pops coming through the speakers. I lifted the ground on the pre with a cheater plug and the hum & static went away.

Did I damage my speakers? I want to try and trouble shoot but am afraid that damage already may have been done and I don't want to make it worse.

Thanks.
tooter
smotyka
62 posts
 
Yes.

Just to make sure & prove that the pre amp is the culprit. You never know how a combination of equipment can cause a problem.

Kr4 made an excellent point about both channels and that the problem could very well be DC leakage. That was the problem I had.
kr4's avatar
kr4
3,424 posts
 
What is high frequency DC, anyway?
zoya
119 posts
 
I think the problem is with the tubes, but not because the tube is going bad, but because it's a low quality brand.
When I got my tube amp, I've experienced similar problem, but I could also hear the modulation that appeared at approx 1 cicle per second. I replaced a pair of GE 6k7 tubes with a pair of RCA 6k7g and modulation stoped.
Try a different brand for a pair of 12au7.
smotyka
62 posts
 
I was told that the high frequency, that was out of audible range and that is why my midrange drivers were modulating as opposed to the woofers. The DC I believe is direct current as oppossed to AC. My problem was related to electrical components not tubes. I did swap to the tubes first to prove that they were OK and hopefully you have a source to try that.
tooter OP
85 posts
 
Zoya,

Thanks for the suggestion. I just tried replacing all tubes with better NOS and no change in the situation.
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