IKEDA IT407 play back problem - hum

by **bogdan** » 29 Sep 2004 11:57

Hi everybody,
I had the occasion to mount an Ikeda IT407

(the 12" actual Ikeda arm), just for "trying", 'cause it's not mine :cry:

, on my SL1100. Well, no exactly "on" but on it's side, in an MDF structure filled with concreat, specialy done for this purpose.
Great experience : the best musicality I've heard with my poor TT system (an AT440 cart). Very easy to mount and to set - is another impression I still have few days after (even if I had to mount aditional weight in the headshel 'cause the At440ML is not enough heavy for this arm).
But one big problem : to much noise, like hum due to grounding problem.
On the scale from 1 to 10 on my amplifier, at 4, the noise made the music not enjoyble.
The arm was grounded through its cable : 5 pin slot mounted on the arm, 2 x rca + ground spade on the phono pre-amp. The mounting informations provided by IKEDA SoundLabs didn't mention that necessary to make extra grounding of the arm, and any way, no screw on the arm's structure alow to do it. And no DIY on an IT407 that it's not mine.

This kind of noise does not exists on the SL1100 with the original arm. I have once mounted on a similar structure an SME3009 (much more difficult to mount and set) and there was no hum with it either (the ground cable included with the original SME cable, was mounted from the arm's structure to the pre's ground).

Anyone have any ideas ?

Thanks

by **Seb** » 29 Sep 2004 12:11

first : an AT440 on such a heavy tonearm !
second : try to "ground" the TT itself - connect the ground of the TT to the ground of the tonearm.

juste une intuition !

cordialement/regards

Seb

by **bogdan** » 03 Oct 2004 00:23

Merci Seb,
Well, in my cconfiguration the TT's ground and the Ikeda ground joined on the phono's preamp ground.
1. I don't see big difference between grounding the arm to the TT and then to the pre's ground and my configuration. And as I said, the arm doesn't seem to be conceived to work like this.
2. Agree about the mismatching of the arm and cart...I did't have something else to try.

Thanks anyway !

by **Seb** » 05 Oct 2004 15:17

strange !!! I throught I answered your message ? my reply diseappers !!

so:

May be the bad matching of the cartridge with the tonearm is the reason of the hum. Let me explain : the at440 is too compliant for that tonearm. As a consequence the frequency ressonance is very low and may be close to the frequency resonnance of the turntable itself ("the noise", 3-4 hz). You hum is, in that case, simply the amplification of the residual noise of your TT.

???

regards

Seb