Rumble

Just purchased another turntable! Brand new Audio-Technica, and it plays my 78s with a certain cartridge I use- anyway I also have a Decent sony table and both of them rumble terribly..... whereas my Gerrard z2000 I can crank it up without any problems- I have six different head shells for the newer tables and the all do it to varying degrees.
So I hooked the A-T through a pre-amp of good quality and still have rumble. Geographical change may help ( ill have to ask my neighbor if I can put my turntables over at his place).
The Gerrard has spring suspension, the other two are whatever rubber feet they use. any suggestions will be tried. My wife said to turn it down, havent tried that yet. Dave

Some things to check:

1. Are the transit locks engaged for shipping? That causes rumble. Some Technics units have a plastic "key" that must be removed.

2. Is the surface the units are sitting on causing the rumble? If the floor is not acoustically sound, the refrigerator in the next room might be shaking the pickups through the shelving.

3. Is the rumble in the discs? Early 78s pressed on cheaper materials naturally rumble. This was not noticed with acdoustic players, because they couldn't reproduce sounds that low.

4. Is there a tonearm resonance between your cartridge and the arm at a rumble frequency of a 78?

Actually the rumble is on my 33's- I dont think i have any 78's that id care to turn up too loud. I have my whole basement for my music equipment- cement floor. I think i may have to do some speaker arranging, there are 6 15" full range speakers (commercial CERWIN/VEGAs). But it still puzzles me why the Gerrard doesnt do that. It has A Shure Hi-Track cartridge, very clean sound.. as well as the others. but they rumble. I have checked for shipping locks- Thank You!
They are not there.... As far as a fridge...I would never come out of the basement.

OH!

You are describing acoustic feedback, not rumble. The speakers are shaking the pickup, which then puts sound in the speakers, which shake the pickup more, etc.

There are several cures for this:

1. Don't put the speakers on the table or shelf unit holding up the turntable.

2. If the units have spring suspension, stuff some foam rubber inside the springs to damp the vibrations (many Garrards already have this).

2.5. With the pad feet, you can put a sheet of foam rubber under the unit, in contact with the table and with the bottom of the turntable base (make sure you don't cover any vent slots).

3. Get something heavy (say a 2x14 board) to sit the turntable on. Put a sheet of foam rubber under the heavy thing, and set the turntable on top of it.

4. Check for a resonance in the tonearm - loud speakers can activate the resonance. Unfortunately, unless you have experience with damping techniques, replacing the pickup with a different brand or model is the only cure.

5. Try the low filter on your preamp. Itf this works, then put a subsonic filter with a cutoff of 25 Hz in the lines to the power amps. (anything below 25 Hz isn't audible anyway).

6. If the turntable is in a shelf unit attached to a wood or plaster wall, make sure the speakers aren't vibrating the wall, and make sure the speakers are not attached to that wall.

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One more thing to check, if it really is rumble:

Check the drive wheels or belts for signs of hardness or cracking.

Howdy Record Changer! You appear to have an abundance of Knowledge. I see you are in indiana. Im on the stateline of MI/IN I thank you for the platform idea. Like I said the preamp i use is top knotch and i believe your idea will work. I have done similar things, i just wish every time i move something i didnt have to rearrange the room. Ill keep you posted,DAVE

Thank You Record Changer! I recently baught a reel-reel on ebay and it was wrapped in a sheet of rubber material and I folded it to where it was under all four feet, and now I can really listen to my albums! Its not that its loud, But with 6 15" cabinets it creates quite a low frequency. Once again thanks. DAVE

For a minute, I had images of you folding a reel-to-reel recorder, instead of multiple pronouns.

It reminds me of the following radio broadcast from decades ago, which I have on a Bloopers record:

"It's a high fly to center field! He backs up to the wall! He hits his head on it! It falls to the ground! He picks it up and throws it to third!"

Now, just WHAT did he pick up and throw to third? His head?

Or was it the wall? The ground? A fly? Center field? Nobody said anything at all about a baseball.