New speakers, new problem

[heavyeleven]

Tonight I brought home a nice pair of JBL L100t's and hooked them up. FM signals from my Kenwood receiver sound great, but I am getting a deep resonant-like build up very quickly when I try to play vinyl with any power at all. I never heard this on my smaller bookshelf speakers hooked up to the same rig, not even when turning good watts to it. Any ideas on what's happening?

The turntable is a Technics Quartz Direct Drive, cartridge = quite old 4-coil Stanton with a new stylus of the same maker. Do I have a bad cord somewhere, deteriorating cartridge, poor connection, or ??? I am currently using older 16-guage "speaker wire" but will switch to a new 14-gauge shortly.

This does not appear to be a speaker problem, but will appreciate any remarks and advice as to what's causing the resonating sound with the LP's.

[pmakres1]

While I'm not sure exactly what you mean by "resonant-like buildup" it sounds as if you may have an acoustic feedback problem. If your new speakers have substantially more bass output than your old, and/or your speakers are located fairly close to your turntable, you may be experiencing acoustic feedback. This can happen and "build up" very quickly as volume is increased. Try moving your speakers farther away from your turntable, or better isolating your turntable from vibration, through the use of isolation feet or other material.

Good luck!

Best regards,

Peter

[pelly3s]

mmmmm table rumble, try putting the table on a large block of soft foam and see if that fixes it.... what model technics is it? with the 1200's you have to almost suspend them to cure the problem, but thats are extremely high volumes

[rgrjit8]

Is the ground wire well connected between turntable and receiver?

I seem to recall that I knocked off a ground wire once when connecting some new toys and that it had a similar effect.

Come to think of it, double check all your connections and switch positions.
Remember to KISS!

[Figge]

hello! what reciever u got? new/old? if its an older one you might wanna try the subsonic-filter on your reciever.

peace!

Fredrik

[Mike Caldwell]

Hello

I second the sub sonic / high pass filter, there's not much below 30hz coming off of a record and turntable other that vibration and rumble from the turntable motor, the floor of the room the turn table is in ( turntable isolation can help some of that) even a slight warp in the record can produce extremly low frequency output. A high pass filter will also make the system sound tighter and wast less power since the amp is not trying to amplify useless low frequency garbage. I have a schematic of a very good active high pass filter that was built by Urie year ago. It sounds good and is easy to build. You would need a pre amp out / power amp input loop to insert the filter into.
If anyone would be interested in it I could scan the print and send it to you.

Mike Caldwell

[B&KMan]

Tonight I brought home a nice pair of JBL L100t's and hooked them up. FM signals from my Kenwood receiver sound great, but I am getting a deep resonant-like build up very quickly when I try to play vinyl with any power at all. I never heard this on my smaller bookshelf speakers hooked up to the same rig, not even when turning good watts to it. Any ideas on what's happening?

The turntable is a Technics Quartz Direct Drive, cartridge = quite old 4-coil Stanton with a new stylus of the same maker. Do I have a bad cord somewhere, deteriorating cartridge, poor connection, or ??? I am currently using older 16-guage "speaker wire" but will switch to a new 14-gauge shortly.

This does not appear to be a speaker problem, but will appreciate any remarks and advice as to what's causing the resonating sound with the LP's.

isolate the problem ...

just turntable or interaction of turntable and speaker.

Keep headphone... the turntable is work good ?? if yes this is a feeback of speaker.

If no, probably, turntable problem, grease of shaft, suspension cartridge is dry, oxidation in pivot of arm, etc...
Of course clean, your stylus, and verified proper ground turntable and ground loop

jean.

[heavyeleven]

Thanks to all for your helpful comments. Yes, the L100t's have substantially greater bass response than the old bookshelf AR's. Apparently the cause of the deep resonating sound I reported was acoustic feedback. The floor of my listening area is an old, uncarpeted hardwood that gets moving with the JBL's.

When I placed the receiver/TT cabinet on a rag rug, the problem disappeared. Receiver is an old Kenwood KR-9400. Turntable = Technics SL-Q300. The "low" filter on the receiver also helped quiet things down, but is not necessary with a rug under the furniture.

[Mike Caldwell]

Hello
Take a look at the speakers when playing a record, better yet
when the needle is between tracks in the silent section. If you see
the cone of the woofer kinda floping back and forth you need the sub sonic
filter / high pass filter. Even with music program you can it in the woofer cone.
Do this at the volume you normally listen at.

Let me know what you see.
Mike Caldwell

[heavyeleven]

Mike, thanks for the idea. I looked and saw nothing flopping around. It would be interesting to see what's going on in the old set up with cabinet on bare hardwood floor, but at this point I'm not curious enough to tear everything apart and re-create the original condition.