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Thumping / Beating Noise From Speakers During Playing

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DeanC

New Member
I have a great pair of Boston A100 and A150, recently though I noticed when I started up the A100s there seems to be this almost thumping or "door knocking" sound, especially prominent near the end of the record. It's very hard to describe, it's a soft thumping sound with maybe one second intervals. I could get a video recording soon when I'm home, but has anyone ever experienced this? The sound is very noticeable, it almost sounds like someone is tapping on the wall. I'm unsure what would cause this or if replacing the woofers would be the best solution.

Besides that they are in great shape, never had an issue.

Thanks for any advice.
 
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If it's only doing it at the end of a record, I'd suspect that there's some sort of excessive subsonic transient coming through from the turntable, such as a cartridge problem handling a warp or a record pressing error.

Do the 150s play OK through the same record without noise?

Regards,
Gordon.
 
Not to the same extent, the A100 is much louder, but it's fairly common on most records I'm using including new ones. I'll try to provide a video tonight if it helps.

I don't think I have a subsonic filter, I have a Pioneer PL-530 and SX-780, not 100% sure what you mean by isolate (Still new to a lot of this!)
 
The turntable is picking up unwanted vibrations from somewhere. You want to isolate it from picking these up. Or a filter was suggested to remove very low, inaudible frequencies that are looping back through your turntable and coming back through your speakers as a knocking sound. If the surface it's sitting on isn't stable enough or if it's too close to your speakers, this can happen. Maybe try moving your speakers/turntable further away from one another and see if symptoms change. I'd also make sure it's only happening with your turntable and not all inputs.
 
That would make a lot of sense considering these speakers are literally less than a foot away. I could probably afford to distance them a bit more. Thanks for the help, glad it's not an internal issue with them!
 
DeanC said:
That would make a lot of sense considering these speakers are literally less than a foot away. I could probably afford to distance them a bit more. Thanks for the help, glad it's not an internal issue with them!
Click to expand...

Playing a source that's less susceptible to external stimuli would seem to be an easy confirmation.
 
With no record playing but using the turntable switch position, turn up the volume slowly until it is at a very loud setting. Does the thump happen anyway? This would be an assurance that turntable feedback is your problem. Look at your switches and see if a group of two is marked "filter". If they are there push in the they one which is a low cycle. Then try the previous scenario again. Very often the low filter will fix the issue unless you are playing extremely loud.
 
If it doesn't do it when playing a CD through the AUX input or the receiver's tuner, that's another way to know it's related to the source not the receiver or speakers.

Quite common for TT's to be placed too close to speakers, or in a few hilarious cases, directly on top. :biggrin:
 
If your turntable is getting vibration feedback. Besides moving speakers farther away, There are infinate types of isolation pads you could also try, under TT legs.
 
I moved the parts a good distance away. I also secured more isolation beneath the turntable (building my own, for now I have Vibrapod feet). The thumping is still there, but it really only occurs at the very end of the record like the very last five to ten seconds. It's strange, I'll take a video I suppose tonight.
 
If it's an automatic turntable, you'd be shocked how much is under the hood in all those mechanisms. Possible something is binding up somewhere down there, or in the tonearm bearings. Does it coincide with the rotation? One thump every time around? Or faster than that, or random?
 
Maybe this is irrelevant, but here's my two cents.

When there is low humidity around here and everything is static charged, I have to keep the dust cover for my Uturn TT open. When the lid is down and the album is over the tonearm doesn't go into the run out groove. It will just sit there and make a thumping or popping noise every time it makes a full rotation until I lift the lid.

Like I said, this may have absolutely nothing to do with your problem, but it's something.:dunno:
 
toxcrusadr said:
If it's an automatic turntable, you'd be shocked how much is under the hood in all those mechanisms.
Click to expand...

Why, whatever do you mean? <G>

retract-drive.jpg


And yah ... it's possibly just a simple adjustment. Most tables will have a screw that's accessible from the top that adjusts both the set down and pick up position. Try turning the screw a bit and see if that cures the noise, AND the arm still sets down properly. On the PL-530, I'd assUme that's the lil hole under the arm rest ...

5734-11.jpg


** Good idea to keep your hand on the cue lever when adjusting the drop position in case the stylus drops off the record. Make sure you run several cycles to make sure the new position "locks" in properly.
 
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