AT150MLX cart + Cambridge Audio 640P Phono Stage

Category: Analog

After listening to my newly formed LP rig for the better part of a year, I started getting itchy to extract a higher level of resolution without spending a terrible lot of money.

Realizing I had three (!) line stage phono preamps sitting unused in my garage, I first decided to see if the Cambridge phono unit plus one of these line stages would outperform the preamp with phono stage I was currently using, a mid-'80s Amber Model 17 which had so far repelled all attempts to replace it.

After trying the 640p into each of the three line stage preamps from the garage, I picked the Outlaw 950, which, although it's a 7.1 ch. digital surround sound processor, it also has an all-analog stereo bypass mode which is surprisingly fast and neutral. It also includes analog bass management allowing me to integrate my sat/sub speaker setup a little better.

Holy moly! This was quite an improvement. My wife actually ran into the room to listen because the sound had so much more presence. We could hear everything more clearly, each note forming and trailing off, and instruments and voices hanging in space. Everything sounded more real, and especially, more "there."

A lot of noise was gone at the pianissimo end, and there was more oomph at the fortissimo end. There was more "jump" to the dynamics. But there was also more subtlety as well. In fact, it showed me that a lot of what gets blamed as surface noise is actually preamp noise. Or something. Anyway, the music definitely erupted out of quieter backgrounds.I immediately put on my gold standard for nuance, a Diana Krall LP mastered on a tube cutter.

Yep--you could hear everything better, and you could hear how each note was formed. You could picture her mouth shaping the words as she sang them.

Now before you go off and buy the Cambridge, I found out something interesting about it. True, it's very fast, articulate, and detailed with a wide bandwidth and low noise. And it's only $169. But it demands an equally clean, fast, articulate line stage to plug into. I originally planned to plug the Cambridge into another preamp I have, a Hafler Series 915 J-FET class A line stage. It was made in the mid-'90s and represented Hafler's last all-out assault on the high end before they gave up and concentrated on pro audio--electronics for studios and for sound reinforcement. Word is that Hafler tried to make the 915 sound like a "tube preamp."

On its own it was musical and warm, and pretty detailed as well, but there was something noticeably nonlinear about it when compared to a really good, fast line stage. But I would not say the Hafler sounds like a tube preamp. It's just rubbery. The 640p plugged into the 915 sounded bizarre--tubby and rubbery rather than sharp, fast, and transparent. Images were bloated and indistinct. Basically the 915 was blunting the speed and linearity of the 640p.

Only when I tried it into a VSP Straightwire II (a very transparent, wide bandwidth state-of-the-art unit from the '80s) pre and then the analog stereo bypass circuit of the Outlaw did the 640p come alive. But come alive it did, and in spades!

Secondly, because it's fast and linear, something downstream can make it sound bright and edgy. Remember that analog bass management that the Outlaw 950 has? For awhile I switched it on, so my satellites were only getting signal above 80Hz. For awhile I was enjoying the extra clarity and dynamic range, but after awhile, this setup sounded bright and edgy, and the stereo image sounded less stable. I flipped the switch and returned the satellites to running in full frequency mode, and it fixed everything: Gone was the edge--tonal balance was restored and everything sounded smoother, and the stereo image firmed up as well.

This actually makes sense. I installed a Cambridge 640A integrated amp at the neighbor's house 3 yrs ago, and that's what the Cambridges bring to the party--fast, detailed, articulate, and yet fully fleshed out and musical. The 640p was obviously designed with the 640A in mind, so other line stages and integrateds that are similarly linear and wide bandwidth will sound good with the 640p.

Well, I listened to this for awhile and began to wonder if the 640p was revealing its true potential. Specifically, since there were still some soundstage and imaging issues that persisted through the change, I suspected that perhaps my cartridge was holding the 640p back. So I did some research, and--although the 640p has a higher gain input to accept low output moving coil cartridges--several enthusiastic A'goner recommendations convinced me to try the high output moving magnet cartridge, the AT150MLX, instead.

The AT150MLX is a high precision, overachieving marvel much like the Technics SL1210 it's mounted in. Both represent the Japanese forte for mass producing high precision units built to ridiculous tolerances, resulting in products that can compete with handbuilt units costing several times as much. One enthusiast said it was not that far off from the Cartridge Man MusicMaker; another said it was the best cartridge he'd heard under $1000, and both of these guys have listened to way more cartridges than I have.

Well, once the AT150MLX broke in, I went through the all the same sonic revelations I'd just gone through with the 640p. This cartridge was providing more of everything--more body to the notes, more detail to the making of the notes, more instrument and room resonance.

What the 640p started, the AT150MLX fully fleshed out. And on top of that, this cartridge has several features aimed at improving stereo separation and balance, and they paid off. The imaging and soundstage became more stable.

The list price on the AT150MLX truly is $499, and there are several vendors that sell it for $399. But for some reason, there are a few that sell it at half price. I got mine for $259 + ship, but last time I checked, J&R Music World has them for $249 with free shipping.

It's fairly easy to describe an audio component that is a little better here and there, but a little deficient somewhere else. But what do you say when *everything* sounds better in every way? That's what this cartridge/phono stage/line stage do together:

You hear more of everything, and everything sounds better. That isn't always the way it goes. Sometimes those details can overwhelm the music and the body of tone--where all you hear is sticks on cymbals, picks on strings, glottal stops, and rosin falling from the violin bow. The AT150MLX + 640p give you those details, but in the proper musical perspective.

They're all part of the overarching sequence of what makes each note form, bloom, and decay. Put them all together with rhythms and harmonies as this signal chain does, and
you get more than a taste of the high end--a strong sense of music being made in your listening room.

And that's what makes it fun.

Turntable: Technics SL1210 M5G with KAB fluid damper on tonearm, brass cone feet, and Sumiko headshell. Original cartridge was Denon DL-160.
BTW: The 12g Sumiko or LPGear Zupreme headshell plus AT150MLX (and extra counterweight on the Technics tonearm) make an excellent effective mass/compliance match at 10Hz resonance.

Preamp: Before: 1980's Amber Model 17 preamp with built-in phono stage

After: Cambridge Audio 640P feeding Outlaw Audio 950 7.1ch pre/pro in stereo analog bypass mode. Used analog bass mgmt subwoofer low level output to sub, but defeated bass mgmt to satellites and ran them full frequency.

Amp: Amber Series 70 power amp (70 wpc into 8 ohms)

Speakers: Mirage Omnisat satellites and Mirage LF-150 Subwoofer (150w internal powering 10" sub). Usable bass down to about 26 Hz, depending on room placement.

Music Listened to:

Leopold Stokowsky & Nat'l Symphony Orchestra: Bizet Suites
Ry Cooder & VM Bhatt: A Meeting by the River on 45 rpm
Van Morrison: Moondance
James Taylor: Best of on Warner
Joni Mitchell: Blue (German pressing)
Count Basie and the Kansas City Six (Pablo)
Laurinda Almeida: Reverie and other transcriptions for classical guitar (Angel)
Laurinda Almeida and Charlie Byrd: Latin jazz (Concord)
L.A. Four: (self-titled) (Concord)
Buddy Rich Big Band: Swingin' New Big Band
Diana Krall: From This Moment On (Verve/Classic Records 200g pressing)
Steely Dan: Aja
Beethoven and Haydn string quartets
Various classical chamber music on RCA Red Seal
Nitty Gritty Dirt Band: Will the Circle Be Unbroken
Veery interesting. Recently I picked up the 640P and bought my old Technices 1300 out of moth balls. Be it hooked up to my SS or tube integrated very nice sounding. My old records still make beautiful music. Good to read your comments on a possible upgrade for my Stanton 681 cartridge.
Good to read your comments on a possible upgrade for my Stanton 681 cartridge.
Glenfihi 06-27-08
I think the AT150MLX and 640p work very well together, showing each other off well. If your SL1300 has the same or similar rectangular double gimbal tonearm as the SL1200, you may want to add the KAB fluid damper. Also, the Sumiko or LPGear Zupreme headshell works very nicely with this cartridge and visually the cart and headshell look badass (black and gold) together.
Nice review. My recent experience with the Audio Technica cartridge came from a used turntable that I purchased recently and it was an eye opener. Once I am done with all my used cartridges, I will get a new AT150 soon. It sounds particularly good with direct-drive turntables which I have a dozen. I am sick of all these turntable manufacturers that are garage operations that can make turntables that spin at correct speed and keep them stable. Direct drive, direct sound, direct music, no bs, no fooling around. Thanks again for the review.
Aren't the technics arms on the heavy side for the at?
the reviewer clearly states he is getting resonance at 10Hz, that is a perfect as you can ask. And he is getting it with the heavier headshell to boot. The Stock technics arm with the stock headshell has a effective mass of 12 grams which is on the low side of med mass. As set up here, it is a perfect match for the AT cartridge. What is it that perpertuates this myth that the 1200 arms are "heavy"? Where does that come from?
Nice review Johnnyb. I am looking at replacing the Grado Prestige Blue on my Thorens TD150 MkII, and am considering the AT150MLX (sticking with everything "150" - HA!). I am thinking these would be a really good match.

Also good to read your discussion of the importance of matching cartridge, phono pre and line stage.