Turntable problem

Recently connected a turntable to my KW550 amp for the first time, every time I attempt to play vinyl the woofers on my speakers reverberate violently. This has never happened before with my cd player or DAB tuner is it the tone arm?

Set up:

MF KW550 amp
Teac Esoteric X-03SE
MF KW DAB tuner
Proac D15 speakers
Thorens 123 TT wt Linn Basic arm A&R P77 cartridge
BCD Engineering rack

Interconnects: LAT International IC 300
Mains: LAT International

 

Hi,

How does it sound? Is it just the speakers moving or do you hear a howling sound? Is the turntable very near the speakers? A rumbling turntable can also cause problems.

Does your amp have a built phono stage? I don't know the amp but a number of amps don't have phono stages inside them.

Sometimes if the arm and cartridge are not setup right, the resultant very low frequencies can cause the speakers to flap. This can be due the resonant frequency of the the arm and cartridge.

BTW is the turntable a Thorens TD124?

Please supply more details.

SCIDB

 

Hi, the turntable is set up in between the speakers on a rack, I would the speakers are about a metre away from the TT. There is no howling sound I did remove the ground wire from the TT to see if that made a difference but had to put it back because I started getting ground hum. I am using the built in phono stage on the amp it is on mm setting as per the cartridge, the azimuth is fine, anti-skating setting is also correct. The turntable is a Thorens 123.

 

feed back maybe the cause,
nando.

 

The phono stage probably doesn't have a warp filter to roll down output below 20hz.
The P77 is a med/high compliance MM and the arm, if the original Basic is high-ish mass. This less than ideal match gives strong subsonic output and you see this as violently flapping cones especially with ported speakers.

You either need to get a better arm/cartridge match or use a phono stage with the recommended IEC warp filter.
I'd recommend both as desirable with ported speakers.
Mechanical arm and cartridge matching often gets overlooked today but is as important as ever if you want the best results.

 

Many thanks I think I will probably opt for a better arm.

 

Noo, get the phono stage with a warp filter as there will still be every chance that the resonance will be there and you will then need to make another purchase. The flapping shouldn't damage your speakers but it looks hideous!

 

what kind of rack is it sitting on as well? you may find that two things will merelly solve the problem,: henley is a good advice, others are blue tack under the feet to isolate 20 hz feed, and the other fact is if you are using the t/t with the dust cover on,
nando.

 

Is this a typo? I've never heard of the Thorens 123 - the 124 perhaps?

 

Good point, even when properly matched you'll get some cone flap though it should be a lot less with the correct compliance/mass match.

On a typical 2 way where the bass driver is also covering the mid you really don't want the thing to be pumping away like a piston. Firstly it can give poor sound and secondly you waste amplifier power and warm the voice coils for absolutrely no benefit.

 

Hi, guys the TT is a Thorens 321! I should know better I've had three of them. Please can someone recommended a make and model of phono stage with a warp filter?

 

The Cambridge phonostage has one - however, it is usually only a feature found on stages aimed at the lower end of the market.

I get almost zero cone flap - even from the sub-woofer at high volumes, and I do not use a warp filter.

 

Thanks, apparently gramAmp2 has one also.

 

Has it?

To be honest I'm not convinced that you have found the root of your problem (though it is not imposable). It could still easily be feedback - howl round is a rare occurrence in domestic situations and just what you describe is the lesser (but much more common) feature of feedback.

A better arm won't solve this issue whatever the cause is.

 

Would you suggest moving speakers further away from TT?

 

It's just subsonic noise. Those of us old enough to remember hifi before the small shiny disk know it well. Either get a phono stage with a subsonic filter or just ignore it, like most of us did.

 

Hi,any suggestions in terms of phono stage?

 

I'd love to recommend but, as a distributor, feel it's unethical to do so. However there are loads around and I would suggest something not too expensive (say under £150). A quick google search or a chat with one of the retailers on here should work.

 

Yes

 

I was referring to people with reflex loaded speakers.

Many stages roll down below 20hz by default and don't advertise this as a warp filter. This includes Naim on all their boards for example.