ike many music enthusiasts, I have amassed a large collection of media which I now need to convert to digital format for posterity.

Since a good portion of the media is in vinyl format, and I had recently donated my last turntable to a needy cause, a new turntable was needed. A friend recommended the  Audio-Technica AT-LP120-USB direct drive turntable. I listened to his and the digitized samples of discs played with it he provided. I was impressed and eventually ordered one.

Audio-Technica AT-LP120-USB turntable

Issues

I liked the features of this turntable, especially the USB output, which streamlined the digitization process considerably. And at holiday pricing ($199 at Best Buy), it was certainly feature-packed for the cost. However, as other AT-LP120-USB owners have reported, the unit has an issue with induced motor noise. Also, some quality control problems regarding the record platter have been reported. I, too, experienced both these issues while evaluating three samples of the turntable.

Motor Noise and Platter Warp

The record platter sits on the motor shaft which is part of the direct drive motor. The motor itself is attached to the chassis without too much in the way of insulation. On all three units I evaluated, I noticed a background noise on quiet passages of good quality vinyl discs and on Side 2, Track 11, of the Omnidisc test record (the sample file below has been amplified 20db to highlight the noise):

AT-LP120USB Motor Noise:

Telarc ‎– DG-10073/74 Omnidisc Test Record

If my vinyl collection were limited to pop, rock, jazz, and soul, I wouldn't have minded so much. But I also have classical and quiet specialty recordings which I need to archive. All three AT-LP120-USB turntables I tried exhibited the same noise. On the second one, I noticed also that the record platter was slightly warped which added to the noise signature (not in a good way).

Noise Gate

The USB output on the AT-LP120-USB is a great convenience. However, there is a noise gate circuit in line with the inboard phono pre-amplifier which mutes the signal from the record when it falls below a pre-set threshold. There is no way to defeat the noise gate, so extreme quiet passages will drop to dead silence and disrupt the continuity of the vinyl disc's surface noise. This can be distracting (listen to the following excerpt at 5, 14, and 22 seconds):

AT-LP120USB Noise Gate:

Solution

The continuous warbling sound could be attenuated using iZotope RX7, but that would add countless hours to the archiving process. The answer to this problem was the Technics SL-1210GR turntable.

Technics SL-1210GR turntable

While (at least in silver) its appearance is remarkably similar to the AT-LP120-USB, the differences are deeper, including the price ($1699.99 at B&H). The AT-LP120-USB and SL-1210GR both have heft (23.5 lbs and 25.3 lbs, respectively); however, the Technics unit has substantially more chassis insulation, larger isolation feet, and a heavier platter. Also, the motor's rotor magnet has its twin mounted on the underside of the record platter which, along with an improved coreless motor design, provides better torque transference and virtually eliminates motor "cogging."

SL-1210GR record platter cutaway drawing (illustration courtesy Panasonic Corporation)

Single-rotor, surface-facing, coreless direct-drive motor (illustration courtesy Panasonic Corporation)

Turntable chassis cross-section (illustration courtesy Panasonic Corporation)

Motor noise virtually disappeared on the SL-1210GR. A comparison of the difference between the AT-LP120-USB and the SL-1210GR reveals that the motor noise is absent on the SL-1210GR.

The following two audio files are from the Telarc Omnidisc test record, Side 2 Track 11. The first is from the AT-LP120-USB turntable, and the second is from the SL-1210GR unit. Use a good set of headphones to hear the difference.

AT-LP120-USB:

SL-1210GR:

AT155LC Cartridge

In some folks' estimation, this is one of the finest cartridges Audio-Technica ever produced.

AT155LC cartridge

I obtained one back in the day at a good price (can't remember) and mounted it on the SL-1210GR's tonearm with assistance from the Telarc Omnidisc set-up and alignment tracks. It just looks beautiful.

AT155LC cartridge and SL-1210GR tonearm

The cartridge exhibits almost ruler-flat response from 20Hz to 23kHz with a slight presence rise at 15kHz. Audio-Technica supplied each cartridge with a copy of the strip chart from the B&K analyzer output generated during burn-in testing:

Original A-T AT155LC cartridge factory test frequency response chart

For whatever reasons, cartridges today don't have the sonic character of this classic. It's airy yet full-bodied response brings out the best in quality vinyl, like M&K Realtime Records For Duke (M&K RT-101), The Complete 4th Movement "Ode To Joy" From Beethoven's 9th Symphony (M&K RT-112), and Malcolm Frager Plays Chopin (Telarc DG-10040).

Playback Quality

I used the AT155LC cartridge to compare the quality of playback on the AT-LP120-USB versus the SL-1210GR. I didn't expect much difference since the tonearm is quite similar between the two; however, I was surprised at the results. The following two files are excerpted from Beethoven's 4th movement "Ode to Joy" on M&K RT-112 release. Both recordings followed exactly the same workflow: source turntable analog output to Radial  J33 phono direct box to Behringer UMC204HD ADC to Audacity on MacOS recording at 24-bit resolution and 96kHz sample rate. Again, use a good pair of headphones to audition these tracks (reproduced below as MP3, original hi-def files available on request).

SL-1210GR:

AT-LP120-USB:

Ode to Joy excerpts in Audacity

To these tired ears, the SL-1210GR has a little more air and a broader dynamic presence than the AT-LP120-USB. But your mileage may vary. I'll leave it as an exercise for the listener to come to their own conclusions on the playback quality.

Cartridge Update

I've been on the lookout for a backup or replacement for the AT155LC cartridge, but have been cautious about plunging into the current cartridge pickings from Audio-Technica. Their website lists the catalog of the latest cartridges along with reviews. I poured over the list for quite a while and thought that the new VM cartridge line was worth further investigation.

Also, I thought there was something fishy about the playback using the AT155LC cartridge. It sounded like there was some distortion occurring along the edges of the sound, but I couldn't put my finger on it. Maybe a new stylus was needed; I've had the original for thirty-seven years, perhaps it was time for a change.

AT155LC with new AT150Sa stylus

I searched for an AT155LC replacement stylus and came up with an "improved" AT replacement stylus for sale by LP Gear. It's called the AT150Sa and costs $210.88 (yes, that's 88 cents, probably converted from Japanese Yen to US Dollar). Oh hell, in for a dollar, in for a pound, or whatever. While there I also purchased an Audio-Technica VM740ML cartridge as back up for the venerable AT155LC, if anything should happen to it. On-line reviews speak well of this cartridge, and its specifications seem reasonable.

Audio-Technica VM740ML cartridge and VMN40ML stylus

Since these additions and updates represent essentially new cartridges, I performed the whole Omnidisc set up routine for both of them (recommended for all turntables and cartridges, really). Of course, an A/B comparison between the cartridges was essential.

Let's Compare, but first...

I noticed while I was recording each of the following music samples that the AT155LC/AT150Sa combination signal was just a little "hotter" than the signal from the VM740ML. I loaded each file in iZotope RX7 to analyze the difference.

AT155LC output signal analysis in iZotope RX7

VM740ML output signal analysis in iZotope RX7

There's about a 2db difference between the output signals with the older AT155LC/AT150Sa cartridge having the hotter output. Thus, to make the comparison fair, I added about 2.15db of gain to the file recorded with the VM740ML cartridge. Stupid human psychoacoustics fact: anything louder sounds better.

First up is a comparison of the "Ode to Joy" Fourth Movement pressing mentioned earlier. Again, good headphones recommended, and original 24/96 files are available on request.

AT155LC/AT150Sa:

VM740ML:

The second comparison is from the previously mentioned For Duke (M&K Real Time Records pressing RT101). (I have an affinity for direct-to-disc recordings.) Below are tests using the first track, a classic, Take the "A" Train.

AT155LC/AT150Sa:

VM740ML:

I listened hard to each of these comparisons on headphones and speakers. I auditioned each track in its entirety first, then switched between each track during playback using the solo and mute functions in Audacity.

A/B comparison using Audacity on MacOS

To my ears, there's virtually no difference between the upgraded AT155LC and the latest VM740ML cartridge. I was stunned. I expected worse performance from the VM740ML: an attenuation of the high frequencies as is popular these days (for whatever reason), a slight masking of the instruments' clarity, a kind of "dumbed-down" sound. No. It's all there just like the AT155LC does it. Listen again for yourself if you don't believe me.

So how can that be? If the AT155LC is tracking at 1.4g, and the VM740ML is tracking at 2.0g, wouldn't you think the latter cartridge be "slower" sounding? I found a comment on Audio-Technica's website interesting and revealing. In response to a consumer's question regarding appropriate tracking force, an AT technician had the following to say:

In the mid-80's, there was a kind of "competition of lower tracking force and high compliance", at least in Japan, and I heard every cart manufacturer was seeking it at that time. So I personally think low tracking force had lingered for decades without any modification. 
About the suspension, since the original VMs can have stability for 1.8g, new VM series have also stability for 1.8 to 2.2. (Of course, we checked the [sic] several tests such as Tracking ability and Stability for long time-maximum tracking force test and so on.) 
The only difference in terms of manufacturing process between 150Sa and 750SH or 440ML and 540ML is the pressure that was given in the process of stylus-cantilever assembly. In other words, New VM series' rubber dumpers [sic] are pressed with higher force compared with previous series.

It would explain why the AT155LC's optimal tracking force is 1.4g while the newest VM740ML is 2.0g. Analogous to a speaker cone's motion, the stylus cantilever's motion is damped by the compliance of the surround at its hinge point--the yoke. The fashion for the 1970s through 1980s was for ultra-compliant cantilever shaft surrounds and, by necessity, very light tracking forces. Since then, I guess the manufacturers, like Audio-Technica, did some more research and found that stiffer surrounds accompanied by heavier tracking forces produced similar, if not better, results. Go figure.