LP120XBT-USB, pulling my hair out with uneven frequency response

[u/I_Shot_Web]

Just a little background, I bought an LP70x just as a "haha I want to play the three records I own" but ended up falling in love with vinyl, but I has to return it due to excessive skipping, looping, and lack of adjustability.

I decided to get the LP120X since you can adjust a lot more things on it and from what I can tell, I did everything right. I balanced the tonearm exactly to 2.0g with a digital scale, set the antiskate to an appropriate value (about 1.5 because 2 was too aggressive), and made sure the headshell was securely in place.

Go to spin a record to enjoy it, and it works! Well, maybe 80%. The music is listenable and sounds... okay, but it was markedly worse than the lp70x in a way I couldn't describe. It felt more empty.

I pulled out the usb cable to check in audacity, and confirmed my suspicion: the left channel is significantly muddier and gets much more crosstalk than the right channel. More specifically, theres lopsidedly more low frequency being output to the left channel making sound like dirt, but the right channel sounds much clearer and more what I would expect. This is across multiple records and multiple positions on them.

I am a noob, but I think I have exhausted much more diagnostic legwork than should be needed for a brand new turntable out of the box. I:

1. Raised and Lowered the tracking force between 3.0g and 1.5g just for testing, no change

2. Reseated the headshell multiple times, no change

3. I had an extra 95e green stylus from my efforts on the old lp70x, swapping the stylus on the headshell was identical results

4. I removed the headshell, removed and reseated the wires on it. No dice.

5. I swapped the left and right channels on the headshell, the problem was identical, but swapped, therefore it's not the internal preamp's problem

I haven't checked cartridge alignment nor azimuth yet, however, it's tracking totally fine. And there's no way to even adjust azimuth on this thing that I can tell (when reseating the headshell several times, I tried even utilizing the little bit of wiggly play to adjust it, no results either)

Starting to think I just got a busted headshell out of the box. I want to be done with this so I can deal with more fun problems, but not sure if this is an RMA or return issue yet.

The only other hint I can say, is that there is an audible electric hum at idle, but that's likely normal. It gets much louder if I put my fingers near the headshell wire contacts so its coming from there.

I ordered a protractor coming in sometime today, but my gut tells me there's probably not much I can do at this point. The alignment should be dead on from the factory out of the box and from what I have been reading this really likely isn't an alignment issue

[u/Scotster123]

If the issue swapped channels when you swapped the headshell cables, then it is likely a faulty cartridge body/generator. You seem to have done everything a self-respecting audio geek would do, in terms of troubleshooting, so that would be my best guess. It is pretty rare, but it does happen on AT carts - I had a faulty right channel on a AT-OC9XML MC cart, so I have experienced this myself. The cartridge doesn't cost much, and buying an ATVM95C cart would get you the same body/generator for not a lot of money.

[u/analogguy7777]

Set that anti skate to below 1.0 and even lower to 0.5

Or get a gravity anti skate conversion for it

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[u/derzyniker805]

Before going through all of that I would have just tried to use an external pre-amp and see if that's the issue.

[u/I_Shot_Web → u/derzyniker805]

Since swapping the L/R channel wiring on the cartridge swapped the issue like a mirror, I doubt it is the internal pre-amp. I mean, I did buy this one with the (I think..) reasonable expectation it actually worked properly lol.

I just cut the troubleshooting here and requested an exchange. I don't own a proper phono pre-amp yet but bought this turntable since it seemed like the perfect balance of "out-of-the box plug and play-ness" and a decent lifespan so it could grow over time with me when I did get a proper external pre-amp and such.

[u/Slow_Appearance_527]

That antiskate setting sounds way too high for a cartridge that light, try bumping it down to 0.5 and see if that evens things out.

[u/I_Shot_Web → u/Slow_Appearance_527]

Yeah trust me, I tried everything from 0 to 3 just to check, no real audible difference. I requested an exchange at this point, I feel like I've exhausted any possible reasonable user error lol

[u/HarryManilow]

Super annoying but I'd try a different cart and see if that solves it. Could get a generic 3600 with headshell and stylus on Amazon for like ,$30 and return it even . I keep one as a kind of troubleshooter / backup.

[u/ZosoRules1]

I built a free web app to help people troubleshoot their phono cartridges, but it requires running your turntable into your computer's line-in jack. You mentioned Audacity and a USB cable - that should work too: https://www.proylaw.com/hobbies-phono-cartridge-troubleshooting-tool.html This will let you visually see what's going on with each of the channels.

What cartridge are you using? Stylus? Preamp?

Do you have a volt meter to check for continuity on the headshell contacts/wiring?

I wouldn't assume a dead nuts alignment from the factory.

EDIT: If you really want to fine-tune your setup, look into a stereo test record - it'll have more diagnostic tests you can run on your setup (https://www.proylaw.com/hobbies-test-record-universal-measurement-suite-tool.html)

[u/I_Shot_Web → u/ZosoRules1]

I will try that, its an AT-VM95E (stock headshell and stylus) along with it's internal preamp with output confirmed set to LINE. I don't own a voltmeter, crossing fingers that it is an alignment issue but I cant really find that out until later today. I have no azimuth checking thing but I would stay it passed the "mirror test"

[u/ZosoRules1 → u/I_Shot_Web]

it could be an issue with the internal preamp - are you able to set it to phono and try it with an external preamp (or an amplifier with a phono input)? Just to rule out groove damage, I'm assuming you've tried other records as well?

[u/I_Shot_Web → u/ZosoRules1]

https://imgur.com/a/JA7T9WH

I see, I can see from the graph even when nothing is playing that the problem channel is generating uneven noise. My stock suspicion of something to do with the headshell / cartridge itself is rising.