Audio-Technica AT-LP120 Preamp Removal (Detailed Instructions Video)

Thanks! I think I've got it down now. Appreciate it. Any thoughts on my question above?

Cheers!

 

I only have the ground wire I added running from my TT to my preamp's ground connection. I really don't think you need anymore, however I have no electrical qualifications and I don't know what part of the world you're in, if that has an impact. I'm in Australia, others on the Forum that have removed their preamp are in the US, so I don't think it's necessary.

 

No - you could end up with a ground loop. Case ground goes through Denon (assuming it's grounded through it's power plug).

 

Just did the preamp removal, following the video. Thanks to everyone involved for making this available. My AT LP 120 is now a dedicated 78rpm table, coupled with the Grado 78C cartridge.
Sounds so good, nice when things go smoothly and are enjoyable.

 

I only use the 78 mode when I'm cleaning with a carbon fibre brush

 

Ha, I hear you. 78s are just...strange. They look weird spinning that fast and the sound is warm and round...sort of thick. I like it a lot.

 

I redid my wiring, I noticed my left channel was louder then the right channel and had to balance when needledropping. So I connected directly to the wires coming out of the tonearm. Issue resolved.

You guys might want to check your outputs coming out of the circuit board loop. If its unbalanced I recommend eliminating that loop.

 

Anyone in the Cleveland, OH area that could do this for me if I bought one of these TTs?

 

I'm experiencing the same thing. Were you able to get this resolved or is it just a characteristic of the pre amp removal? I'm wondering if I made a bad connection somewhere I used wire nuts on mine.

 

Are either of you able to solder the wires together? I initially used wire nuts, but eventually soldered them together for a much stronger connection.

 

I'll have to give soldering a shot. I can tell a huge difference in sound already, but it seems like there is a lot of pops on records that were quite at one time. Thanks for the help!

 

It might just be that more detail is coming through without that dreaded preamp. Maybe a good wash for the record may help?

 

Really want to try this - really afraid to!!!

 

I played a spin cleaned record and it wasn't nearly as noticeable, maybe it's just more sensitive now. I still think I will solder it eventually.

 

More sensitive is probably right! Enjoy your table with that dreaded preamp out!

 

That's what I did by default - I soldered the phono lead onto the same bit of circuit board (and same bit of solder) where the tonearm wires came out of the arm, so it's essentially a join.

 

I just removed the preamp from my PL-120. It's a slightly different procedure (as the phono/line switch is under the platter), but I probably wouldn't have known exactly what to do without reading the rest of this thread. Thanks!

 

Hello. I just removed my pre-amp and unfortunately I'm in the mode of trying to eliminate a hum from my right speaker, but no hum from the left. It wasn't there prior to the removal. I also noticed that the turntable hums when the turntable is turned off and the stylus is still live. Shouldn't the turntable be fully off when switched to off? Any help would be greatly appreciated. Thanks

 

First things first: The stylus is still live because it is a separate circuit; 4 wires (Right+Gnd & Left+GND) run from the cartridge through the tonearm to the 2 output terminals (RCA jacks or wires with RCA plugs: Right+Gnd & Left+Gnd again) to your main control preamplifier or your receiver. It takes no external power as that is generated by the stylus within the cartridge.

The right speaker hum problem sounds like a poorly connected wire. Take a wire with an alligator clip on each end, attach one end to the Right channel GND at the tonearm and the other to the Right channel GND at the output terminal and see if it still hums. If it doesn't hum with this connection, you have a bad (solder joint?) connection somewhere that you will have to track down.

Turntable hum when it's turned off (or even unplugged) may be the cartridge picking up RFI from a transformer in another piece of equipment (Grado used to be famous for this; there were just some turntables you couldn't mount a Grado on because of the hum picked up from within the TT itself. (I was a victim)). Try moving the TT or other equipment away from each other.

If you 1) unplug the TT RCAs or 2) turn off your control preamplifier or receiver and the TT -STILL- hums you have a problem I can't help you with.

Arvid

 

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What kind of a mat is that? Looks vaguely like carbon fiber or possibly Aramid?

 

Thanks for the quick reply. I rewired the RCA connections and wasn't able to remove the hum, and it's only in the right speaker. Shouldn't the noise be in both speakers? The hum is there with the turntable power cord unplugged. When I r[/url][/IMG]emove the ground screw from the receiver it gets really loud. Also, touching each bare wire on the RCA white and red wires I get a loud buzz from each of them.

Please see photo of hookup. Thanks

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Sorry if I missed something - but - did you do something to your TT other than just remove the preamp?

 

Nope, I just removed the pre-amp. I'm trying to figure out where the hum is coming from. It wasn't there before. See above comments regarding my situation. Thanks

 

Hum is obviously coming from the cartridge then. I pulled the preamp on mine and added RCA jacks and a GND connector to the rear panel to avoid having to trace all the other connections, keeps the signal path clean. I ran a 3-conductor wire (I think old headphone wire) from the -LEFT- of the thick GND braid (left of braid is 5 connections: (left to right) GND GND WHITE RED BLACK). I used the first GND and WHITE and RED wires and ran these to the RCA jacks and split the bare copper third wire to the RCA GND lugs. KISS don'tcha know.

Anything beyond that you'll just have to play with it. Use some bare wire to connect your GND connections to narrow it down.

Arvid