Vinyl Asylum: REVIEW: Audio Technica AT33ML/OCC Phono Cartridge by Ross

Model:	AT33ML/OCC
Category:	Phono Cartridge
Suggested Retail Price:	$500
Description:	LOMC
Manufacturer URL:	Audio Technica

Review by Ross on January 04, 2012 at 18:45:52
IP Address: 74.230.247.153 Add Your Review
for the AT33ML/OCC

This review represents a work in progress.

Last spring I acquired a Linn LP12/Ittok LVII. Actual setup and serious listening began in the fall. I had previously used an AR ES-1 with a stock arm and a Shure V15vmr. Luckily I had an extra V15vmr body on hand so I was able to move the stylus assembly between tables, keeping set up on the AR intact if needed. The rest of my system can be viewed in my profile. I like my PV5 preamp, but the phono stage is microphonic and exhibits a higher noise floor than the other inputs.

Through the LP12 I could easily hear an improvement in reproduction- lower noise floor, better retrieval of low-level detail, even better bass (not something the LP12 is known for). What was lacking was the soundstage width and depth that I had with the AR table. With the LP12 I heard a ribbon of detailed sound between my speakers. Instrument placement was easily identified. Massed vocalists were distinct, but everything sounded like it was clamped firmly between my speakers. If I listened hard enough, I could hear depth but this was not a primary strength. I particularly noticed the lack of overall depth when listening to well recorded mono LPs. The sense of layering at the mid point was greatly diminished. This was a strength of the AR setup.

Over time, I began to feel that the cartridge was the weak link. I decided to try a MC cartridge and initially considered a Soundsmith/ Denon 103d or an AT OC9 ML/II or III. I needed a SUT for either cartridge so I acted quickly when I found a K&K Lundahl 9206 offered at a very good price. It had been configured for 1:10 step up. A few weeks later I found an AT33ML/OCC at a great price as well. I understood the 33 to be a step up from the OC9.

With great anticipation I carefully set up the cartridge and wired everything together. Instead of beautiful music, I was greeted by HUM. Great gobs of loud hum that overwhelmed everything else. I tried rerouting grounds, checking all connections, moving the SUT in every direction etc. I also asked for help from the people I purchased the SUT and cartridge from. I removed the SUT and tried the cartridge straight into the preamp. Hum and noise were back at baseline levels isolating the problem to the SUT. However, due to a lack of cartridge gain, I had to turn the volume up so high that tube noise became an issue. BUT, I could hear music and what I heard was promising: great treble extension, wide soundstage and very natural reproduction of strings and brass. I also heard breakup on loud passages and very muddy bass. I knew that my setup was not optimal, but at least I knew that the cartridge worked!

While pondering all of the above, I want back to my AR TT. Gone was the detail heard from the Linn. Music sounded flat and lifeless so I knew there was no turning back. Curiously I noticed a speed error that I was previously unaware of…sustained piano notes warbled slightly and there was now a quiver in some vocals.

Finally I spent a day buried in the AA archives. One poster suggested that extreme hum was not only a grounding issue but also connected to isolation. The offered solution was to wrap the SUT in aluminum foil. OK, what the heck so I wrapped the SUT in a large sheet of aluminum foil. I did notice a reduction in hum but the level was still objectionable. When experimenting with different configurations of the foil, I noticed that hum seemed to change in level and intensity when I focused on the SUT input connections. I opened up the SUT case and made sure that all connections were solid and that wiring was carefully routed etc. I moved a few wires and bent one of the input ground tabs to correct what I perceived to be interference. I was rewarded with an additional reduction in hum. Further investigation in the archives brought out that some listeners had eliminated hum by star grounding everything to the AC supply ground and also by lifting the ground connections in the SUT. I use an Isobar isolation box that has a grounded connection to the wall AC. Both the TT and preamp have 2 prong AC cords. I quickly connected a wire to the chassis of the Isobar and touched the other end to various points on the SUT. When I touched the shell connection of an input jack, hum virtually disappeared in that channel. Same result in the other channel. So I ended up with a wire running from each input shell to the Isobar. Hum was now down to baseline levels and serious listening could begin !

I was greeted by a wide soundstage, with more depth than I was used to from the LP12. Width extended beyond my speakers. Midrange and treble reproduction is outstanding. I could hear greater transient response in the treble. Plucked strings of an acoustic guitar sound real. I could hear individual trumpet valves opening and closing. With the V15, I would hear all of the notes merged together in a continuous sound. Now I could hear individual notes as they were played. With cymbals I heard the strike of the drumstick in different places on the cymbal and then the shimmer of the cymbal itself. Before I would hear a strike that merged into the shimmer with little distinction between. Greater audible depth restored some of the sense of layering I used to hear on mono recordings. When listening to “Thembi” by Pharaoh Sanders I was able to follow both hands of the pianist during a piano solo. The piano was located to the left and at about a 45’ angle to the mic, but I could hear the left hand notes separate and distinct from the right hand notes. There was audible space between the 2 hands that approximated the actual spacing on the keyboard. I never heard this before and I am very familiar with the recording. In a similar vain there is a lot of percussion in this track; wooden blocks, cymbals, hits to the side of the drumhead etc. With the AT33 I could hear the snap of each percussive hit as a distinct sound even when several occurred at the same time. Through the V15, simultaneous hits were merged together and I lost the snap that was now hard to miss.

But with the good, comes some bad. I noticed that the arm would move slightly outward when using the cueing lever to raise the arm. I heard some breakup on loud passages. Bass was still muddy and weaker than I expected. While I had a wide soundstage, channel separation was so great that I now have an audible hole in the middle. Surface noise is more prominent. Playing “clean” records sometimes resulted in noticeable residue on the stylus. Further investigation revealed that my problems could be from several issues, inaccurate alignment, low VTF, incorrect VTA, too much antiskate and incorrect loading. Without a supply of resistors on hand, I could not experiment with loading, but all of the other parameters could be adjusted. I carefully rechecked alignment and found I had to adjust it a smidgeon. I increased VTF from 1.5g to 1.8g. and I reduced antiskate to about 1.2. Another listen showed improved bass response but still a bit lean for my taste. Breakup was corrected and the arm no longer moved when raised by the cueing lever. I took a careful look at the cartridge while playing and noticed that the tail was slightly high, thus the cartridge was not parallel to the surface. I then lowered the arm slightly to affect VTA. Bass improved, but treble may have lost some sparkle ? More trial and error ahead as I continue to adjust VTA and grounding. I will also experiment with resistor loading.

What I hope I have shown is that careful setup is extremely important to extracting the best audible results and that the AT33ML/OCC is not forgiving of setup deficiencies. This is not a negative to me but rather an indication that the AT33 is a higher precision instrument than the V15.

So far this has been a frustrating experience because of the problems I encountered and because I have heard glimpses of the sonic potential that is tantalizingly just out of my reach.

So this is still a work in progress that I will update as needed.

Thanks for the bandwidth !

Product Weakness:	Surface noise more prominent. Very sensitive to setup. Lean bass.
Product Strengths:	Treble extension, detail, transient response

Associated Equipment for this Review:

Amplifier: Heath AA-111 (stereo 6bq5)
Preamplifier (or None if Integrated): Conrad Johnson PV5
Sources (CDP/Turntable): Linn LP12 / Ittok LVII
Speakers: Triangle Titus 202 / AR3a (as subs)
Cables/Interconnects: Audioquest GSnake
Music Used (Genre/Selections): Jazz and Rock
Time Period/Length of Audition: 2 weeks
Other (Power Conditioner etc.): Isobar AC Extension Box
Type of Audition/Review: Product Owner

Amplifier:	Heath AA-111 (stereo 6bq5)
Preamplifier (or None if Integrated):	Conrad Johnson PV5
Sources (CDP/Turntable):	Linn LP12 / Ittok LVII
Speakers:	Triangle Titus 202 / AR3a (as subs)
Cables/Interconnects:	Audioquest GSnake
Music Used (Genre/Selections):	Jazz and Rock
Time Period/Length of Audition:	2 weeks
Other (Power Conditioner etc.):	Isobar AC Extension Box
Type of Audition/Review:	Product Owner