Vinyl Audio

Equipment => Turntables => Topic started by: BSD2000 on August 05, 2011, 04:14:42 PM

Title: Upgrading an Audio-Technica AT-LP120-USB turntable
Post by: BSD2000 on August 05, 2011, 04:14:42 PM
Here's a few pictures of the inside of my nephew's AT-LP120-USB turntable. After looking it over, we decided to remove the built-in preamp / USB PC board and route the tonearm cable directly to a pair of RCA jacks out the back.

This mod is only recommended if you already have a phono preamp, and don't plan on using the built-in preamp or USB output. My nephew uses a Cambridge 640P, so the built-in electronics were not needed.

I removed the PC board, cut out the stock black RCA cable and routed the grey tonearm cable to two Neutrik gold plated RCA's ($7 for the set from Mouser Electronics). Both RCA grounds were soldered together with the grounding wire in the grey cable. Next, Holes were drilled through the back of the top cover. You can mount the RCA's through holes on either half of the case, I choose the top half for convenience. Just make sure it doesn't interfere with anything else inside or out (cover) when locating a spot for the RCA connectors.

I used a banana plug from an old speaker binding post as the ground. I just soldered it to a wire leading to the 'grounding star' already there from the factory.

I used WBT silver solder for all of the connections, but that's only because I bought a 1lb. spool of it years ago when silver solder was cheap. Now, the same spool costs an arm and a leg. I do recommend using good solder since the signal level that will be flowing through it is very low, but any decent brand of solder should do.

The end result was dramatic. Everything sounds more open, with better extension in the bass, smoother mid-range, and cleaner highs. From what I seen on the PC board, the tonearm wire goes through a few solder connections, possibly a few resistors, then through a switch before exiting through the hard wired RCA cable. Not the cleanest path for such a low signal to take.

The next mod will be to replace the tonearm wire with a couple feet of bulk Cardas 4x33 gauge tonearm wire. Buying it by the foot, it usually goes for ~ $8 a foot, so it's not to costly. Two foot should be plenty. I'll post a short how-to article when we decide to tackle that upgrade.

Pictures are attached. You must be registered to view them.
Title: Re: Upgrading an Audio-Technica AT-LP120-USB turntable
Post by: lshin80 on August 06, 2011, 02:49:58 PM
Nice upgrade. My first choice when I was going to buy a TT was the Technics SL 1200 Mk 2, and later upgrading it with better tone arm, external power supply, etc. What  I was interested in was the direct drive, which allow an extremely low wow and flutter amount: less than 0.01%, a value that only higher end belt TTs have. Unfortunately, when I decided myself to buy it, I discovered that Panasonic had already dropped all the Technics line :(
I didn't want an used one, and since all the cheaper direct drive clones, like the Audio Technica (which is the best among all) have a typical wow and flutter value of 0.1% - ten times higher! - I decided for a good belt drive, the Pro-Ject RPM 5.1, which doesn't need dramatic upgrades, and has 0.08% wow and flutter value.
Title: Re: Upgrading an Audio-Technica AT-LP120-USB turntable
Post by: nick52284 on August 06, 2011, 09:07:22 PM
it was definitely a great improvement, i'm interested in hearing what it will sound like with the upgraded cable, and i was thinking about going with a denon dl103R, the 160 sounds great but it seems like there is much more musical information to extract from a record as i've heard what a ZYX sounds like and nearly crapped my pants, makes me really wonder what the mega bucks cartridges, turn tables, and audio processing equipment sound like...

the nephew, lol



Title: Re: Upgrading an Audio-Technica AT-LP120-USB turntable
Post by: lshin80 on August 07, 2011, 07:03:53 AM
How does the Cambridge Audio preamp sound like?

The Denon 103r may not be suitable to the standard Audio Technica tonearm, since it has a stiff stylus and thus needs heavier tonearms to have a full, deep sound. The Audio Technica and Technics tonearms are more suitable to cartridges like the Denon 160, which have a less stiff stylus, and require lower tracking force and lighter tonearms.
Title: Re: Upgrading an Audio-Technica AT-LP120-USB turntable
Post by: nick52284 on August 07, 2011, 11:42:31 AM
the cambridge sounds good for an entry level solid-state preamp, however; I've listened to my uncles tube pre-amps and they have a sweeter sound, smoother all around, the lows are deeper, the highs are sweeter, and the midrange is usually right where it should be. the Denon 160 is what i have now, if i would try the 103r i can add a weight to the head shell to help with the mass of the arm.

Nick
Title: Re: Upgrading an Audio-Technica AT-LP120-USB turntable
Post by: BSD2000 on August 07, 2011, 12:02:16 PM
Hey Ncik - if you want, you could borrow my DL-103R and see how it sounds. I have a headshell that has screw on weights for up to 4 grams of added weight. Ishin80 is right though - the 103 may not be the best match for an arm like yours due to the compliance of the 103 being so stiff.

I did experiment with 103R on my Technics turntable and it wasn't half bad, but the 103R is capable of better performance with a higher mass arm.

I think today I'll mount the 103R on the heavier headshell and see how it sounds.
Title: Re: Upgrading an Audio-Technica AT-LP120-USB turntable
Post by: BSD2000 on August 07, 2011, 12:04:56 PM
We could also replace some of the parts (caps, op-amps) inside the 640p and improve the SQ a bit, if you feel adventurous.  ;D
Title: Re: Upgrading an Audio-Technica AT-LP120-USB turntable
Post by: BSD2000 on August 07, 2011, 05:31:17 PM
Here's a few samples of the DL-103R with a 2g weight (VTF set to 2.5g) on a really beat up Technics SL-235 turntable:

Gary Numan - Cars (Extended Remix - 45RPM)


Earl Klugh - Jolanta (from the LP 'Finger Paintings' on MFSL)


I used a Musical Fidelity X-LP phono preamp using the MC setting. No step up transformer was used. The recordings are in 320K .mp3 format for streaming purposes.

As you can hear, the bass is severely limited and begins to roll off after 50hz or so. The mid-range is nice and clear - as are the highs. There was some oscillation in the tonearm at a few points in the song so the tonearm was resonating at a much higher frequency then is optimal. Overall, the DL-103R wouldn't be a good match for a light Technics style tonearm.
Title: Re: Upgrading an Audio-Technica AT-LP120-USB turntable
Post by: nick52284 on August 07, 2011, 07:26:57 PM
thos clips sounded pretty good but i hear what you are saying about the roll off

hmm, i wonder what would match this tt that isn't crazy expensive but would be a decent upgrade? i guess the thing i should actually upgrade first is the pre-amp to maybe a tube preamp?

Nick
Title: Re: Upgrading an Audio-Technica AT-LP120-USB turntable
Post by: lshin80 on August 08, 2011, 05:30:56 AM
i guess the thing i should actually upgrade first is the pre-amp to maybe a tube preamp?

Nick
I agree. Upgrading the preamp will better show off the Denon 160.
Title: Re: Upgrading an Audio-Technica AT-LP120-USB turntable
Post by: BSD2000 on August 10, 2011, 09:09:00 AM
Here's a quick peek inside the 640p.

We can replace the power supply caps, maybe the input caps too. I have some spare 8pin DIP sockets and a few Burr Brown 2134's, LM4562's, and maybe a couple AD823 op-amps we could try in it.
Title: Re: Upgrading an Audio-Technica AT-LP120-USB turntable
Post by: srsairbags on January 30, 2012, 01:25:52 AM
i basically joined the forum to see the pics for this mod . . . noicee . . :)
Title: Re: Upgrading an Audio-Technica AT-LP120-USB turntable
Post by: BSD2000 on January 30, 2012, 03:40:49 AM
i basically joined the forum to see the pics for this mod . . . noicee . . :)

Let me be the first to say: Welcome Aboard!  8)

I plan on continuing the upgrades on the AT-LP120 turntable in the next few weeks. The next upgrade will be replacing the tonearm wire with Cardas 4x33g, going from the connecter in the tonearm straight to the RCA outputs.
Title: Re: Upgrading an Audio-Technica AT-LP120-USB turntable
Post by: srsairbags on January 30, 2012, 06:07:35 PM
i basically joined the forum to see the pics for this mod . . . noicee . . :)

Let me be the first to say: Welcome Aboard!  8)

I plan on continuing the upgrades on the AT-LP120 turntable in the next few weeks. The next upgrade will be replacing the tonearm wire with Cardas 4x33g, going from the connecter in the tonearm straight to the RCA outputs.

appreciate it

Originally i bought the AT lp120 usb for a friend abroad . . . cause of the voltage selector and built in preamp, but somehow i got stuck with it  . . and now im in love with it. I do want to remove the onboard preamp just like you and purchase a Cambridge 540 preamp. Also want to buy a decent cartridge to go along with the preamp.
Title: Re: Upgrading an Audio-Technica AT-LP120-USB turntable
Post by: nick52284 on March 30, 2013, 06:43:57 PM
Well after a lengthy hiatus I finally got the cables in, possibly tomorrow we'll upgrade the tone-arm cables and align it, then possibly post some samples!

Nick52284
Title: Re: Upgrading an Audio-Technica AT-LP120-USB turntable
Post by: nick52284 on May 23, 2013, 01:30:01 PM
the upgrade is complete, awaiting some tests and cartridge swapping, i heard it with the 160 on it and WOW! the seperation is amazing now, distortion and background noise is much lower! pics and samples will be posted as soon as the tests are done!

Nick
Title: Re: Upgrading an Audio-Technica AT-LP120-USB turntable
Post by: hagcel on February 06, 2014, 04:00:24 PM
How hard it is to replace the tone arm wire? I see where the tone arm wire is soldered to the PCB - but where does the other end go?
Title: Re: Upgrading an Audio-Technica AT-LP120-USB turntable
Post by: shadowlord on February 14, 2014, 02:59:42 PM
well, that depends a bit on your tonearm. (and how the wire is mounted and run)
I did it twice in the past.
On a Dual where it was surprisingly easy and a Eumig where it was much more complicated.

Title: Re: Upgrading an Audio-Technica AT-LP120-USB turntable
Post by: BSD2000 on March 06, 2014, 06:24:03 AM
How hard it is to replace the tone arm wire? I see where the tone arm wire is soldered to the PCB - but where does the other end go?

When I upgraded the wire, I ran it from the tonearm straight to RCA jacks that I added to the back of the turntable; I bypassed the PCB and removed the preamp/ADC board altogether.

I'm still looking for the pictures I took during the upgrade, I don't remember where I put the files. When I find them, I'll post them.
Title: Re: Upgrading an Audio-Technica AT-LP120-USB turntable
Post by: GoodVinylLover on July 11, 2014, 08:15:46 PM
It would be great to see those pictures :)
Title: Re: Upgrading an Audio-Technica AT-LP120-USB turntable
Post by: jmp45 on December 19, 2014, 10:21:48 AM
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.
Title: Re: Upgrading an Audio-Technica AT-LP120-USB turntable
Post by: MemoryServed on January 25, 2015, 07:21:42 PM
Just thought I'd share my experience with the on-board pre-amp bypass mod:

When I initially bypassed the AT120's pre-amp, I was using an AT440MLA cartridge.  At the time, the only thing that was bypassed was the pre-amp itself (making the my mod look almost identical to the mod at the beginning of this topic, except not nearly as clean in the cable management department).  I immediately noticed an improvement in the treble response, and can say without reservation that the overall sound quality improved with this mod.  Also, there was no hum present, or any perceivable signal interference present at the time.

Unfortunately, my AT-440MLA suffered some unintentional damage (i.e. over-tightening), at which point I switched to the Denon 103R (a natural alternative, right? xD)
Ignoring the mis-match of the tonearm and cartridge issue (brought up by lshin80 earlier in this thread), I immediately noticed the presence of the dreaded "mains hum" (i.e. 60hz hum) in the sound.  After removing a DIY pre-amp from the mix (substituting for a Schiit Mani), the sound of the mains hum dropped slightly, but was still very present.  Moreover, the hum would increase nearly 20dB when the direct drive motor was on (not necessarily even spinning), and even higher when the cartridge was placed over the record.

I discovered (largely through trial and error) that the hum I was hearing was largely correlated to the AT120 direct-drive motor being on. In an effort to minimize the noise, here are the things I did (no particular order):

1) Completely bypassed all PCB boards that carried the cartridge signal.  That is, I soldered the tonearm cables so that they now go directly out to the step-up transformer (SUT).  I did this by de-soldering the EMF shielding and tonearm cables from their first PCB (i.e. the board with the traces), and routed them directly to two RCA connectors I added for the initial mod.  Note: I soldered the white and red wires to their respective posts, and solder the remaining green, blue, and black wires to the ground posts.  Also, I kept the EMF shielding around the tonearm cables and stretched it to cover them as much as I could.

2) Dramatically shortened my interconnects.  Originally, I was using 3' cheapo RCA cables out to the SUT.  In replacing these, I purchased two 6" Schiit RCA interconnects, and connected them between my RCA outs from the tonearm to the input side of the SUT.

3) Completely bypassed the grounding to the spring post with the cartridge ground wires (note the grounding to the spring post from the tonearm ground cables in the pictures provided by BSD2000).

4) (Optional) Although still connected in my configuration, you may be able to get rid of any kind of dedicated outbound ground wire altogether.  However, this will obviously be TOTALLY dependent on your own configuration.

Doing all of the above dropped my noise floor and mains hum below were it was even audible, and allowed me to hear why the Denon 103R is considered such a great cartridge.  Also, there is now no additional noise when the motor is turned on, nor when the cartridge is moved over the platter.

Caveat: I am bringing my signal (after pre-amping) into an Apogee Rosetta AD.  Setting the resolution to 24-bits and the sample rate to 48khz was the configuration I used with regards to the claims above. 

Hope this helps!
Title: Re: Upgrading an Audio-Technica AT-LP120-USB turntable
Post by: BSD2000 on January 26, 2015, 04:36:45 AM
I keep looking through all my memory cards and on my drives and for the life of me, I can't find the photos I took when I swapped the cable to Cardas. I think what happened was the SD card that had the photos on it got wiped by accident and lost forever.  :(

As I recall, it wasn't that hard; I just removed the connector at the headshell, un-soldered the old wires, soldered on the Cardas cable and taped the new cable to the old and pulled it through the tonearm. I kept the Cardas cable tightly braided through the tonearm and I did fish it through the braided mesh on the bottom of the tonearm base (just as you mentioned) to keep the cable shielded as much as possible. The Cardas cable was terminated to two female RCA connectors on the back of the turntable with individual grounds, not shared like in the photo. The grounding lug was kept as it was, attached to the rest of the ground cables in a 'star' configuration. After completing the bypass, the PCB was no longer being used, so I removed it.

[attach=1]

The Cardas cable made a huge improvement in the overall clarity, giving music a more controlled and tighter sound. I highly recommend replacing the tonearm cable with Cardas - the improvement is quite dramatic for such a small monetary investment.  :D

As you mentioned, there was a slight bit of 60hz hum, but it was relatively benign; down around -60dB, which is barely audible once the music starts. Using a good quality interconnect can help reduce it even further. You mentioned about bypassing the ground to the spring - I may try that to see if it makes an improvement.

The only thing I found from when I did the wire upgrade was a few test recordings, which I can share if anyone is interested. I didn't do any recordings before the upgrade, only after is was completed.  :-[
Title: Re: Upgrading an Audio-Technica AT-LP120-USB turntable
Post by: BSD2000 on January 26, 2015, 04:45:42 AM
Caveat: I am bringing my signal (after pre-amping) into an Apogee Rosetta AD.  Setting the resolution to 24-bits and the sample rate to 48khz was the configuration I used with regards to the claims above.

I love the sound of Apogee Rosetta AD's; I have a 96K model myself. :D
Title: Re: Upgrading an Audio-Technica AT-LP120-USB turntable
Post by: BSD2000 on October 31, 2015, 10:14:29 PM
I managed to find some of the pictures I took while doing the upgrade.  :)

If I was going to do it over, I would have ran the wires directly to the RCA jacks instead of to the PC board.
Title: Re: Upgrading an Audio-Technica AT-LP120-USB turntable
Post by: GoodVinylLover on November 02, 2015, 05:51:29 AM
I managed to find some of the pictures I took while doing the upgrade.  :)

If I was going to do it over, I would have ran the wires directly to the RCA jacks instead of to the PC board.

It's never too late :) Thanks! ;)

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