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

Discussion in 'Audio Hardware' started by FrankieP, May 20, 2013.

  1. KevinT2018

    KevinT2018 New Member

    Made a box to mount the left & right rca cables and ground. Going to solder this into instead of cutting out the usb & preamp. Any issue with not removing the preamp ? Saw a youtube video with preamp & usb intact
     
    samn likes this.
  2. Dieguite

    Dieguite New Member

    Hi everyone! I use to read the forum and usually found the answers to my newbs questions before make it! :) But this time I need help! Made my MOD with no problem and the sound quality is better now but have a problem with the ground. I hear a Hum and tonight I noticed if I touch the arm and the plate the HUM goes almost all. I twist the ground cable from the TT to a new cable to the PREAMP (Art) but leave connected the cable to the TT's ground too. My question is: Do I need to remove the connection to the TT's ground and leave just one to the preamp directly? BTW I check the cables and other things with my old Techincs TT and no problem. Must be something with the AT120 and the ground.

    Thanks for your help, and sorry for my poor english! :S
     
  3. Ben Adams

    Ben Adams Forum Resident

    Location:
    Phoenix, AZ, USA
    I don't know what to tell you beyond my own experience. I attached a long wire to the ground in the AT-LP120, and it's connected to the grounding screw on my ART. I don't have any hum.
     
  4. RobCos02330

    RobCos02330 Well-Known Member

    Location:
    Mass
    Sorry for the dumb question-I'm electrically inept-What type wire should I buy for the added ground wire connection? Is there a particular gauge size and wire type? I assume I attach a spade on one end with a cramper(got that covered) and splice the other end to the internal ground wire and cap it off? All doable-but im clueless about what I'm buying. :laugh:
     
  5. Ben Adams

    Ben Adams Forum Resident

    Location:
    Phoenix, AZ, USA
    I just used some insulated wire I had in my toolbox ... No idea about gauge. As I recall, the ground wire itself is pretty slender.
     
  6. RobCos02330

    RobCos02330 Well-Known Member

    Location:
    Mass
    I just realized, I may have a spare am antenna with a ground attached that I could steal and splice to the internal ground. Let's hope that together it's long enough to reach the receiver.

    That video was great and much appreciated! Can't wait to finish tonight and test her out.
     
    Ben Adams likes this.
  7. Ben Adams

    Ben Adams Forum Resident

    Location:
    Phoenix, AZ, USA
    I didn't see this before. I would remove the preamp entirely. As long as any part of the signal is passing through it, the sound is being degraded, even if you flip the bypass switch. It's a lousy turd of a preamp and it does no one any favors.
     
  8. Budysr

    Budysr Well-Known Member

    Location:
    Pensacola, FL.
    When I removed the preamp in my 120, I used maybe a piece of 16 or 18 awg wire, but anything in that range would be fine. Ironically, I don't even have the ground wire connected to my preamp(Art DJ preII) as It doesn't need it. No hum at all in my setup and WITH the ground connected to the Art, I get just a slight bit of hum, but still not a lot.
     
  9. Ben Adams

    Ben Adams Forum Resident

    Location:
    Phoenix, AZ, USA
    Now that's weird.
     
  10. RobCos02330

    RobCos02330 Well-Known Member

    Location:
    Mass
    Finished tonight and the difference is INSTANTLY noticeable. All traces of sibilance are gone-at least so far. Very clean sound. Wow. I had assumed that all the stories of success might have been even just a tad exaggerated-I'm more than happy to have been proven wrong!
     
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  11. Budysr

    Budysr Well-Known Member

    Location:
    Pensacola, FL.
    Yes it is. Only thing I can think of is that the TT is already internally grounded--even with the ground wire added in the preamp removal mod. Or maybe its just my particular setup and the wiring in my house.
     
  12. jmp45

    jmp45 New Member

    I have the hum issue with I'm assuming the preamp. Wouldn't another way to disable the preamp non destructively would be to just unplug the preamp's power cable and switch to phono? It looks like a passive trace to the output cables although with a couple of caps in the mix. Why not just add a mini toggle switch mounted on back to cut the power to the usb preamp board?

    I did notice that the hum increases slightly the moment the cart is over the platter. The preamp is not under the cart in that position. There may be some other issues contributing.
     
  13. Ben Adams

    Ben Adams Forum Resident

    Location:
    Phoenix, AZ, USA
    All I can say is that I removed the preamp entirely and have had no problems with hum whatsoever. Heck, this could a problem with the cartridge or tonearm wiring. In my experience, TT hum is usually caused by either the ground not being hooked up properly, or a loose cartridge lead.
     
  14. jmp45

    jmp45 New Member

    The hum happens with both headshells, AT95E and M97xE. Ground loops can be an issue to track down. On one of my old Marshalls I had quite a bit of hum compared to my others. The culprit was a lead wire to the control pot buss was a little too close to one of the transformer wires. Moved it a half an inch or so, tie strapped, hum is gone. Anyhow, just looking for a simpler non destructive resolve for this preamp issue.
     
  15. Ben Adams

    Ben Adams Forum Resident

    Location:
    Phoenix, AZ, USA
    Those caps in the mix are the problem, regardless of whether the preamp is powered on or not. It needs to be bypassed completely.
     
  16. jmp45

    jmp45 New Member

  17. Ben Adams

    Ben Adams Forum Resident

    Location:
    Phoenix, AZ, USA
    You really don't even want it in there, man. It's a subpar USB preamp anyway (cuts out at low volumes), and as we keep saying from experience, those capacitors are a huge problem (veiling the sound) even if you're bypassing it. If you're altering anything your warranty is voided, so why not just remove it completely?
     
  18. Stefan

    Stefan Forum Resident

    Location:
    Montreal, Canada
    This video reminds me that I've been meaning to mention on here about the new black model , the AT-LP120-BK. Looks nice.
     
    Ben Adams likes this.
  19. Ben Adams

    Ben Adams Forum Resident

    Location:
    Phoenix, AZ, USA
    It'd be great if they'd just bring back the PL, the model without the preamp.
     
  20. All Rights

    All Rights Forum Resident

    The PL has a preamp, it just has no USB. The phono/line level switch is under the platter. The preamp circuitry is configured differently than the LP and appears to be more difficult to extricate. (IMHO):)
     
  21. Ben Adams

    Ben Adams Forum Resident

    Location:
    Phoenix, AZ, USA
    Ah, I see. Thanks for that. I've been under a misconception about that model, then!
     
  22. jmp45

    jmp45 New Member

  23. Deangersmith

    Deangersmith New Member

    Location:
    UK
    Hi,

    Thank you for this information, I watched this video at work earlier, I have the AT-PL120 first edition, not the USB version, the one with the switch underneath the platter. So it looked a little different inside but the basic wiring schematics were recognizable after a bit of investigating. I have bypassed the pre-amp and all seems good, the turntable is playing fine and I think I can hear an improvement in the sound. I will have to play a few different LP's. The thing is I wasn't using the pre-amp before anyway, I was sending the signal through an external amp, so it's difficult to tell straight away. I also purchased an ISOkinetik ISOMAT 1 ACRYLIC TURNTABLE MAT on eBay a few days ago, got rid of the standard felt mat that came with the turntable. Do you know if they are any good?
     
  24. Ben Adams

    Ben Adams Forum Resident

    Location:
    Phoenix, AZ, USA
    They'e supposed to be, but I haven't used one myself. But pretty much any other mat is better than that felt slipmat!
     
    DarkAudit likes this.
  25. mattanderson

    mattanderson New Member

    Hi all,

    New member and LP120 owner here.

    Thanks to all who have contributed their knowledge, experience, needledrops, etc. Very cool community you have here.

    A couple thoughts:

    #1. Has anyone tried bypassing the tonearm circuit board yet, as Stefan suggested back on page 1?

    #2. I'm a little sad to see everyone using wire nuts for their splices. If you guys don't want to solder, but are willing to make a trip to the store for parts, why not use something like crimp-on butt connectors? I think that's what my plan will be when I do this mod.
     

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