Loud Boom on Akai AP206C

[adrian cooke]

Hi everyone,
I am new to the forum and this is my 1st post would like some help with my AKAI AP 206c direct drive player.When connected and played the player gives a loud booming sound when volume is raised above 50% on the amplifier (Sansui G 4700),ground lead is also connected to the amp.Any suggestions would be welcome.I am hooking it up to the phono input,by any chance does the AKAI 206C have a inbuilt phono that could be causing this problem.
Regards,
Adrian.

[Alec124c41]

This sounds like acoustic feedback. Isolate the turntable from the speakers. They should not have any contact with whatever the turntable is on.
If necessary, put a board under the turntable, and foam under that, or foam under the turntable.
You could also damp the inside of the base with modeling clay.

Cheers,
Alec

[adrian cooke]

Thanks Alec,
will try it out this evening and keep you posted.
Regards,
Adrian.

[adrian cooke]

Hi Alec,
I am back after a long time,i tried the foam under the Akai and the speakers are away on the floor,they are floor stander units and i have the Amp and Turntable side by side on a table higher than the speakers and behind the speakers but still there is a loud hum/boom coming when i increase the volume,i even tried changing the amp to a pioneer but smae results.
Any suggestions...

[SupaWales]

Adrian..

Do you hear the hum / boom noise between the songs on an LP?

What happens if you turn up the volume between 2 songs on an LP, or at the beginning / end of an LP while the stylus is still touching the record?

Can you plug headphones / earphones into the amplifier and if so do you still hear the hum / boom?

Trying to work out whether you have acoustic feedback loop from stylus to loudspeakers or have a 50Hz hum due to an earth problem.
Is the ground wire from the turntable securely attached to the GND terminal adjacent to the phono input sockets on the amp? This is the wire that is attached to the cable coming from the Akai with red & white plugs on the end of it.

[adrian cooke]

Hi Wales,
thanks for the reply,the hum is there while plying the songs and also when i lift up the tone arm and increase the volume.There is no hum when i am less than 50% on the dial it only comes in when i increase voulume above 50%.The ground wire is secure on the amp.Note i dont face this using the same amp and my denon 300f,technics sl d3 or garrad zero100.

[SupaWales]

OK Adrian.

Check the wiring in the headshell that connects to the cartridge.

Compare the wiring colours & orientation with a headshell & cartridge from one of your working turntables.
If it's different, try altering the connections on the Akai headshell to be the same as the one you're comparing it with.
Alternatively, try using the cartridge & headshell from one of the other turntables on the Akai as a test.. or try the Akai headshell & cartridge on one of the other turnatbles.

Once you've tested etc. let us know what you find so that someone can tell you how to cure the hum.

[adrian cooke]

Hi,
i have matched the wiring same as on the Head shell of the Technic's table,as im using both audio technica carts.But have not tried the headshell of another table, i'l try that today and see. Thanks.
Rgds,
Adrian.

[adrian cooke]

Hi Wales,
Swaped the headshell from Technics to Akai but still got the humming above 50% on the amp volume.So i isolated the player from the stand by placing a foam cut out of 2 inch thickness and a acrylic slab of 1/4 inch thickness on top then placed the turn table on top and am now able to increase volume upto 75%,beyond this there is a loud hum,any suggestions are welcome,could it be that the Turntable is not compatible with the 2 amps i have.
regards,
Adrian.

[SupaWales]

Hi Adrian.

Can you post a picture of your equipment?

I would like to see how each item is located relative to each other.

I think you might be having a problem with the magnetic field from the mains transformer in the amplifier being picked up by the cartridge due to the cartridge being physically too close to the amplifier's internal power supply transformer.

You could also try moving the turntable further away from the amp, or to the opposite side of the amp and noting whether the hum gets better or worse.

A turntable placed directly above or below an amp on a rack with only a small amount of distance ( 50mm / 2 inches say ) can be affected by the large magnetic field generated by the equipment above / belows' mains transformer.