Very little sound from my turntable’s left channel.

[RockaMarka88]

Hi, everyone.

Recently I’ve been having difficulties with my setup. I have an Audio-Technica AT-LP120XUSB turntable, a Technics EPC-450C-II cartridge and a Technics SA-8000X receiver.

When playing records in Stereo mode, the left channel is much quieter than the right. When I unplug the RCA cables from the back of the turntable and plug them back in again, the sound returns, but only for a few minutes. There is equal sound from all speakers when I switch to Mono or 4Ch Discrete mode, and everything else - tapes, Aux and FM radio - sounds fine in Stereo, but for some reason the Phono selection plays up.

I’ve tried cleaning the cartridge, the connection pins inside the tonearm and the phono inputs/outputs in both the turntable and receiver, but still no joy.

Anyone have any ideas what the problem might be?

Many thanks,

Mark.

 

[furui_suterioo]

Could a bad cap on the preamp of the receiver, hopefully not the cartridge. Maybe try with another turntable if you have one.

 

[Doug G.]

Switch the inputs to the receiver. If the problem switches channels, the problem is with the turntable/cartridge. If the problem stays in the same channel, the problem is in the receiver.

However, being you are using a strain gauge cartridge (a very good one, I might add), you may have a problem with the voltage supply to the left channel in the cartridge from the preamp. Of course, it could be the cartridge, itself, too. The way to find that out is to switch the leads on the cartridge and see if the problem follows the same channel or not. If the problem switches channels, the problem is in the preamp. If the problem stays in the same channel, the problem is with the cartridge.

Doug

 

[RockaMarka88]

Thanks for the replies, guys. I think I’ve solved the problem.

Rightly or wrongly, I’ve been using my Technics EPC-450C-II cartridge for all vinyl formats - mono, stereo and matrix quad as well as Quadradisc. The left channel in stereo started to disappear, and in SQ quad mode the decoder’s front channels took about 20 minutes to start working after switching the unit on. I decided to switch back to my Audio-Technica AT20SLa to see if this would make any difference. The left channel has returned, and all channels in the SQ decoder work straight away without having to “warm up”. I’m delighted that the sound has returned to its former glory!

I now know that the AT20SLa is “moving magnetic” and the EPC-450C-II is “semiconductor”, but I’m not entirely sure what this means. Does anyone know how the differences in cartridge would affect the performance of my equipment?

Many thanks,

Mark.

 

[Doug G.]

The difference is that a MM cartridge outputs without any external voltage source. A strain gauge cartridge needs to have a DC voltage supplied by the preamp for it to output anything at all.

Also, the output from a MM cartridge must be corrected by an RIAA circuit to equalize the high and low frequencies. The strain gauge cartridge doesn't require that,

Doug