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

Did you actually try it stock first or was the M44-7 a post surgery addition? - The obvious concern is what was the effect differential pre and post with a high (relative) output voltage cartridge? I am more interested to know if it has enough output bump to get past the assumed cap presence of the claimed bypassed (phono setting) pre board inside so as to not have to risk cracking open the proverbial egg...
;-)

 

I was using a Ortofon Red prior to the Shure and I prefer it out of the two never tried it pre modding the pre amp - the M447 tracks a lot better and hides a lot of surface noise recommended if you buy a lot of secondhand vinyl

 

Roger that, thanks for the background - Looks like Ortofon 2M Red has an Output voltage at 1000 Hz, 5cm/sec. - 5.5 mV which is just slightly above half of the M44-7 output. Will order a M44-7 and try it before I even consider a mod - I am looking for a less surface noise susceptible cart anyway for old vinyl - not a lot of new stuff available round these parts yet. If I don't like the sound characteristics with that and the AT95E, then I will see about the mod which seems to make sense based on the commentaries herein. I may try to make the mod easily reversible though with soldered plug-in clips inside if I do go that route - will take some extra time but would help should I try to sell it later and have a need to reverse it for someone less concerned and who wants to use the onboard USB capability....
As my username implies, my ears are basically hamburger meat having gone through a full career of seriously heavy pressure changes (via Valsalva) and even a few nasty vestibular hits from breathing HELIOX and Nitrox mixed gases so there is a big chance my quasi-leather eardrums won't lift the veil over the sound everyone speaks of anyway - we'll see...
;-)

 

That makes sense, and I can understand why you're being cautious. Good luck with the new cart!

 

Got my TT today - finally (Shipping across Canada takes a long bloody time)! First impression review video is rendering as I type with 30 minutes more processing time before I can start posting to the Tube. So far I like the build quality - will it hold up over time is another question given where it was built? Am I uber-impressed with sound quality at this stage? Not really but I am also not unimpressed either. Would I classify it as superior to my old "sleeper" Fisher MT-6250 TT - absolutely not (still upper direct drive midfi IMHO so anyone got one for sale?). Better than an old Linn or Rega (sold many of their RP3s with RB200 so one I am very familiar with) or a Thorens top tier model - no way Jose! Good for what I got it for (DJ bumping and scratching)? Maybe but I suck in that department anyway which is why I went cheap with this particular niche TT. Fun? Hell yeah!. Veiled - Perhaps, but need more listening time in a quiet house (didn't get that with wifey TV and bathroom rennos going on). Video to follow and certainly more feedback to come as I put this puppy through the grinder in the coming days....

 

Uploading as of the timestamp of this post. URL when upload and rendering is complete is:

 

Just ordered the Shure M44-7 with extra headshell and a digital weigh scale to make sure tracking force is correct. I have trust issues with the counterweight markings on Chinese turntables. Let's see if they are bang on or not?
;-)

 

Hello. I just got a 1240. I had read on another forum that while the preamp is the same as the 120's, switching it off truly bypassed it (and the offensive remaining caps); anyone know if this is true? If not, has anyone seen seen directions/vids for the 1240. I'm going to use a Rega Fono Mine A2D and Nagaoka MP-110 and Pro-Ject cork mat with mine. (might want to see disassembly instructions even if I decide to not mess with the pre... I'd like to detach the dreaded Reverse switch!)

Thanks folks.

 

My one and only bump. Anyone? Thx

 

http://forums.stevehoffman.tv/threa...-the-hood-with-high-resolution-photos.379277/

 

Well, I done gone and done it so may be parting company with my new AT-LP120-USB real soon as I just listed it on our local used for sale site. I stumbled across a Thorens TD 165 turntable for a super good deal that needs a wee bit of help but is in pretty good shape overall. Plan is to restore it to its former glory. Here it is:

 

Video Sitrep:

 

hi, i inherited a LP120 turntable recently, and I noticed a really irritating high pitched whine that would change in pitch and loudness all on its own even when the turntable is at rest i.e stationary platter, needle in the air.

the volume of the whine would change (but not by much) when i touch my finger to the tonearm but it never completely goes away.. I assumed it was a grounding issue so I performed this modification in hopes for better sound and grounding. I got the better sound, but it did not cure the whine at all.

I made a recording of the whining using my phone placed at the speaker and it sounds accurate when I played it back on my computer. I have uploaded it here: https://www.sendspace.com/file/cl4foo

It sounds exactly as in this file, basically.. eeeeeeeeeeeeeeeeeeeeeeeeeeee... EEEEEEEEEEEEEEEEEEEEEEEEEEEE!!!! eeeeeeeeeeeeeeeeeeeeeeeeee... and goes on and on..

I've hooked it up to my Onkyo A-9050 amplifier on the "phono" input and attached the grounding wire to the grounding post on the amp.. removing this grounding wire introduces a whole lot of noise so I know that the grounding connection is working and definitely needed.

I have twisted the rca connectors in the amp in case it was a bad connection, but that didn't fix anything either.

I have twisted and removed all 4 connectors to the cartridge and reconnected them to rule out a bad connection, and no luck either..

The Onkyo amp is very new, and the whine goes away on the phono inputs once I remove the RCA leads so I know the source of the noise is definitely from the LP120.

I was hoping to find some help and some other suggestions of what to do, if anyone has encountered a similar problem before, the whine is loud enough to be heard even during loud music so it isn't much fun listening to anything right now

Would appreciate anyone's help

**edit: forgot to mention as well that I turned off all other devices other than the amp and the turntable as perhaps a noisy circuit was causing the whine.. but no luck as well.. even turned off the wireless router located about 5 meters away on a different power line.. nothing

 

uploaded a video with the audio of the whine/ringing for easier listening:

 

Here's some to go with that.

 

Sold my AT-LP120-USB today - opportunity came knocking with a better vintage table (for my purposes) so I will be bailing from this thread. Good luck all!

 

Currently, I have my un-modded AT-LP120 connected directly to my Onkyo's Phono line.

If I end up doing this mod, I will not need an external pre-amp since my Onkyo receiver will be amping the signal from the TT, correct?

Also, what gauge wire should I use for the extra ground?

I just want to make sure that I have all my ducks in a row before taking the plunge. Thanks in advance!

 

I just wanted to add modifications I have made minus the pre amp surgery. I use my USB to needle drop MP3 for in the car and at work on my crappy computer speaker.
I have put a cork mat down which reduces some rumble.
I switched out the cart and headshell with an Ortofon 2M Red and blue Ortofon headshell. Big improvement in sound. Set up with the Technics cart gauge lineup. Once dialed in very little igd and siblince.
I added mass to my existing counter weight. Instead of paying for a new heavier counter weight I super glued two big washers at the end. They fit perfectly in the end. I can't even see them since I made this modification.
With some inexpensive upgrades this table sounds great.
I know it will sound better with surgery but thought I would share my experience with this table. I also have my technics SL-210 for my hi-fi listening. Next upgrade Ortofon blue. Been saying this for a year now.

 

Hey all, newb here. I joined just so I could comment on this thread. Thanks to Frankie p for making the video! Not sure if this thread is still being monitored, but any help would be appreciated.

I echo Thanh's question above: what gauge wire should I use for the ground? And also, I'm planning to connect the AT to a receiver (Yamaha rx-a750). How would I connect the grounding cable with spade connecter to the receiver? Is removing the preamp still ok if it's going to a receiver or is this mod only recommended for dedicated external preamps?

Thanks in advance everyone!

 

Pretty awesome thread. Thank to everyone that contributed the videos and tips etc..

My brother did the mod for me last night. He decided to leave the physical board in (although all wires from it have been cut.) He also replaced the RCA cables with a quality set of grounded cables.
Here is the video of the mod - Take a look and please let me know what you think!

Post Mod Inside Turntable - Preamp Bypassed, Board Left in and New RCA's with Ground:


Also here are some before and after videos of the sound. This isn't an accurate representation of sound difference because both videos are just recording from a cell phone.
But wondering what you guys think. - I feel like the highs are brighter, but in some ways I feel I may have lost a little bottom end - does this make sense to any of you?
Im getting a Bellari VP-129 External Preamp and wondering what the difference will be after that...

Sound Clip Before Bypass:
ASLP 120 Before Preamp Bypass »

Sound Clip After Bypass:
ATLP 120 After Preamp Bypass »

Let me know your thoughts!

 

I think it would be impossible to judge changes using a cell phone as the recording device. Small changes in the angle it's held, how it was held in your hand, and the exact location in relation to your speakers, etc, etc, etc. Pre/post needledrops would have been better. Enjoy the table.. I'm sure if the mod was correct, you'll get an improvement with an improved pre.

 

Thanks for your response, I do wish I didn't use a cell phone now that It's done.
I was just wondering if anyone else noticed that they seem to have lost some bottom end after the mod.
I realize everyone's ears are different...
The only thing different we did was leave the board in the unit - although the two wires are clipped and the connector has been removed - so there is nothing passing through it. Just a ground wire soldered to it (see in video)

 

Have just purchased one of these decks with an Ortofon 2M Blue. I'd gone in with the intention of just getting the cartridge to upgrade from the 2m red on my Pioneer PL30K but saw this and really liked the look of it, along with what I'd read about it on the forums thought I'd have a go as have never been quite happy with the Pioneer.

So far with the Blue it is sounding good - have run through a couple of albums so far and it sounds promising, info on here seems to suggest it needs time to open up so wont judge it just yet.

Couple of questions: Does it need the extra ground wire that gets created? I see the sense in adding it whilst doing the job but is it a requirement? If so I need to get something suitable for a long run (5M).

Also, I can, and will try it, but has anyone added a rubber mat to these instead of the felt one, or even a combo of the two? I have the thick rubber mat from the pioneer I could use, however I cant stand how any bit of dust sticks to it so wondering if I could use the felt one on top of the rubber?

 

I'm fairly new to this hobby and just modded my ATLP120 as I picked up an Azur 640p off Craigslist pretty cheap. I'm fairly certain you need the extra ground wire to connect to your preamp or else you'll get a hum. I personally use cork mat so I don't know about the felt/rubber, someone else will have to chime in.

 

Yes, the ground wire is needed to connect to the preamp. And a rubber mat is definitely better than felt for this table. I tried making a cork mat based on instructions I found on the web, but didn't like it as much as the rubber. The rubber definitely helps dampen motor rumble.