DIY Audio Projects Forum

Hi!
I bought a Teac TN-300 turntable about six months ago and I've been having problems with feedback sound. This only occurs while the turntable is playing at a high volume, and the problem increases on songs with a lot of bass. This doesn't happen with other devices and I've tried different cables. The amplifier is a K-12G that I put together over the weekend and I'm using the preamplified output from the TT.
The speakers are on the floor (concrete floor) and the TT is on a desk (not a heavy or robust desk, almost everything on it vibrates when the volume is up). The TT is also close to one of the speakers (two or three foots distance). I've also reset the settings of counterweight and antiskate, but it doesn't make a lot of difference.
As far as I've read, this could be a mechanical vibration issue and I should try isolating the turntable.

I'm thinking on building a wall shelf for the TT. My questions are:

Would putting the TT on the floor get the same results as putting it on a wall shelf? Not to leave it on the floor for the eternity , but to see if building the shelf would help.

And how far away from the speakers should the TT be?

PS: The speakers highlight a lot the bass (these are from a Sony mini-component) and I don't think I like that. What characteristics should I look for when buying a replacement?

Thanks in advanced guys!

Hi, Turntables are indeed sensitive to picking up vibration and feeding back. The pickup is an electro-mechanical device and that is how it gets the sound off the record. Yes wall mounted shelves can help...provided the wall isn't subject to vibration itself. The floor might work. If you have a dust cover for the turntable, try removing it and see if it works better. Often they are pretty flimsy and will make the feed back situation worse. A long while back I had that problem with one turntable. Being a cheap skate (and not to solvent at the time) I used a bunch of 8X8X16 cement blocks in a 24 inch X 24 inch, 36 inch high arrangement with a decorative ceramic tile on top to make a turntable table. I covered it with a cloth. It worked fine. Just don't stub you toe on it (ouch). Pretty much anything that either is quite sturdy (and does not vibrate) or isolates the turntable from the source of vibrations is helpful. If you build a shelf...anchor it into wall studs and support it well. If you want a lot of ideas go to vinylengine.com and ask on the forums. Great folks there.

Good listening
Bruce

_________________
Some of my DIY Tube Amplifier Projects:

• PoddWatt: 5751 / EL84 Push-Pull DIY Tube Amplifier Project
• OddBlocks: KT88 Push-Pull DIY Tube Amplifiers (Mono Blocks)
• ForeWatt: ECC802S (12AU7 / ECC82) DIY Tube Preamplifier Project
• GrooveWatt: Tube (Valve) RIAA Phono Preamplifier Project

Thanks Bruce
I tried putting the TT on the floor and there was no more feedback. But then I remembered having small pieces of some kind of dampening plastic (some kind of clay?) that came with a computer, I cutted them and put it under the four foot of the TT and they also worked very well even when placing the TT on tp of the desk.
Now I'll have more time to build the shelf, there are some very simple shelves on vinylengine.
Thanks again Bruce

PS: Blocks? I can't imagine having a pile of blocks in my room just to be able tu turn up the volume xD guess I lack passion

Well, that's the nearly free option... the more aesthetic ones will cost you

Cheers!

_________________
-= Gregg =-
* Ratings are for transistors - tubes have guidelines*
Home: GeeK ZonE
Work: Classic Valve Design

How to check for TT feedback:

The room should be absolutely silent, and anyone in it, including cats, dogs and mice, dead-still. No ceiling fans, machinery - nothing.
With the volume at 0, put a record on the TT and place the stylus on the record with the platter still.
Very carefully and quietly, gradually turn up the volume. If you can get to very nearly full volume with no feedback, you are fine. Otherwise, you will need to find a way to isolate the TT.

Hey Peter, thanks. I solved this some time ago following those same steps.
It has been almost 4 months and I'm finally building a very simple shelve for the TT. I'll post some pictures of it this weekend.