Audio Prism Mantissa Preamplifiers

Audio Prism Mantissa Preamplifiers 


All tube dual mono line level preamplifier


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[Jan 30, 2002]
Alan Speed
Audio Enthusiast


Transparency, Detail, Imaging, Soundstage


At this price none

I am not usually moved to do this sort of thing, but I had to after hearing this pre-amp. I only tried it out, out of curiosity, after seeing the reviews on this very web site and I have to say that I agree with every comment of the other reviewers. Madrigal Laboratories (Mark Levinson) certainly knew they were onto a good thing when they re-branded this as Red Rose, they were obviously very aware that that the sonic qualities of this pre-amp could justify a very much higher price or rip us poor audio addicts off, whichever way you wish to view it.

As you can see I have used 2 Audio Research pre-amps previously, and in my brother and I's opinion it blows them both away. I would guess that this pre-amp would fare very favourably against the ARC LS15 and dare I say it, give an ARC LS25 a run for its money.

My pre-amp has the seperate power supply which I am sure helps significantly. Anybody out there who is sceptical about this pre-amp and whatever your taste in music, should try one out if you get the chance, you will not be dissapointed.

Music listened to:- anything from Miles Davis to Slipknot.

Krell KAV 300CD
Audio Prism Mantissa Pre-amp
Krell KSA100 MkII Poweramp
Sonus Faber Grand Piano Home Speakers
Transparent Musiclink Super Interconnects (Upgrading to Ultra CD to Pre-amp)
Transparent Speaker Cable
Kimber Powercords

Similar Products Used:

Audio Research SP14 & SP15

[Oct 07, 2001]


Transparency, tonal balance, frequency response (found 1/2 octave of missing bass), and CLEAR highs), soundstage, build quality, appearance, etc


If you want "full featured" look elsewhere. Be warned, it won't sound as good. If only it had the features of my SFL1

This is the best kept secret in high end audio. Even at the stratospheric prices Levinson sell this at as a Red Rose, this piece is up to the task, and could be considered a bargain.

The Mantissa produces the blackest backgrounds of any preamp that myself or my buddy have had in our systems. The level of detail is astounding, as is the solid state (the good part of SS) like bass, with the tube warmth and openness in the highs) All this without being able to be labled from either camp...the best of both worlds. Compared to my Sonic Frontiers SFL-1 (a bargain in its own right), I saw gains on every front (see "strengths"). Improvements in soundstage width and depth were, to say the least, significant.

It took me 10 seconds to decide I wanted one, and 2 years to finally track one down. It was worth the wait. Easily the most significant improvement to my system since my reconversion to vinyl. It's awful nice when the owners of at or near top of the line SF and CJ gear are a bit envious.

No, I'm not too keen on the dual volume controls, but, if that's what it takes to get this sound, it really isn't much of a sacrifice. I've had nearly a dozen preamps in and out of my system in as many years. Some were mine, some borrowed, none stack up the Mantissa. The parade is over, time to upgrade my phono stage.

Similar Products Used:

Replaced Sonic Frontiers SFL1. Have had extensive experience with a Mantissa on my buddy's system for three years.

[May 27, 1999]
Gill Loring
an Audiophile

Music! That's what this whole crazy hobby of music! reproduction in the home is all about. Having been a hobbyist for many years and a weekend sales person in high-end audio (first at Nuts About Hi-Fi in Silverdale, WA and since the beginning of 1999 at Acoustical Magic in Kirkland, WA) for the past 4 1/2 years I have been exposed to many preamps both tube and solidstate. The most muscical and accurate one commercially available has been the MANTISSA series from AudioPrism.
In my search for musical nirvana in home reproduction I have run across several pieces of equipment that I refer to as "fundamentally right". These are pieces of equipment that seem to excel at music reproduction independently of the rest of the associated equipment including the most important factor-the room. Thus, late last summer at the VALVE show in Silverdale, WA I heard the Wisdom Audio Adrenaline speakers for the first time in a less than friendly room but realized they made music (I sell these at Acoustical Magic).

Such was my reaction upon first hearing the original MANTISSA ($1,995) in my system. It was better than the similarly priced Audible Illusions which was available for comparison at the same time. Then I had the opportunity to hear the SILVER SIGNATURE ($3,995) which simply improved upon it in every way. It is tonally balanced (my first criteria for any equipment) with an extremely low noise floor (I recently had an opportunity to compare it a a $34,000 pre in balanced mode and the MANTISSA was equally quiet) presenting the holographic sense of the recording venue expected with great tube preamps ending up making music. Lest you think this is the warm sound of tubes rolling off the frequency extremes and making things all "warm and cuddly" put a bad source in front of it being either CD or a poorly mastered and pressed piece of vinyl and it will let all the flaws flow through. The right CD can burn your ears off. It has bass extension (try Jeff Beck's latest CD) with a sweet and detailed high-end.

Needless to say I purchased a MANTISSA in my case the SILVER SIGNATURE and have owned it for three years. It should be pointed out that in all this time it has never once blipped, never failed and always worked as advertised. This cannot be said of other preamps of my acquaintance. This past fall I got the itch to change tubes after using it for 2 1/2 years 6-8 hours every day (after I first purchased it I had tried several different tubes and found those supplied the best balanced) I talked to Victor Tiscareno, chief designer at AudioPrism, about the need to change tubes. He asked me it it was working fine and I confirmed that it was. In short, he told me not to worry unless a tube failed, apparently, a very rare occurrence. I have talked to owners of some other highly regarded tube preamps and they have told me they have to change tubes every 8-18 months.

The MANTISSA which has a separate power supply uses two tubes per channel-a 6922 for the gain stage and a 12AU7A for the output stage. These tubes are always on even in the "standby" position with the voltage reduced to prolong tube life. Two stepped attenuators are used one for each channel. I'm sure AudioPrism would be happy to answer further questions. They have a website at .

I can just hear someone saying, "He must listen to small jazz groups all the time". Yes, I do love jazz but as I write this I'm listening (experiencing?) Beck's "Odelay" on vinyl (yes, it's better than the CD and an incredibly inventive piece). Therefore, my evaluation of the MANTISSA/SILVER SIGNATURE is based on listening to virtually all kinds of music and in the context of a number of different stereo systems.

However, most of my listening has been done on my home "reference system":

AudioPrism ACFXs and Quiet Lines for power conditioning of the following
Well Tempered Reference Turntable/Arm with Grado The Reference Cartridge
Aragon 47K Phono Preamp
Pioneer PD-93 CD Player (used as a transport)
Theta TLC with TLC Power Supply
Aragon D2A2 D/A
Denon TU-680NAB Tuner
AudioPrism Mantissa Pre-Amplifier/Silver Signature
Conrad-Johnson MF-2300A Amplifier
Snell B Speakers
MIT cabeling mostly with 2 sets of Music Metre Silver interconnects
AudioPrism Isobearings and The Vibrapod Company Vibrapods for resonance control
Living/listening room with several thousand records and CDsj

I've taken the time to list equipment in order that you may have a context in which to evaluate my review of the MANTISSA. However, again I would emphasize that it will stnad up and make music in any system. It had no problem acquitting
itself in a system with a $12,000 turntable/arm/cartridge/phono preamp, $9,500 CD player, almost $30,000 in amps and $30,000 speakers not to mention several thousand dollars in cables. What came out was music.

P.S.: Yes, I do listen to jazz as I'm now doing with "A Tribute to Jack Johnson" by Miles Davis.

[May 20, 2000]
Paul Chung


Very musical,transparent & wide soundstage.


Dual stepped attenuator awkward to operate.

A couple of weeks ago, I saw a set of Audio Prism Debut & Mantissa in a second-hand shop and bought them on the spot. The Company has been taken over by Red Rose Music and the pre and power amps are now selling at nearly twice the old prices.
Great sound for a bargain basement price. Make sure you change the stock tubes. For the Mantissa, I am using a pair of GE 7308 for the gain stage ( Sovtek 6922 stock ) which made a significant difference. For the output tubes, I replaced the stock tubes with the RT 5814.
Great amps value for money.
My only complaint is the dual stepped attenuator is awkward to use compare to the remote volume control of my Joule-Electra LA-100 MKIII.

Similar Products Used:

Matisse - Fantastic linestage

[May 13, 1999]
F. Sonic Smith
an Audio Enthusiast

I ordered my AP Mantissa sound unheard after auditioning several solid statepreamps to replace my McCormack TLC-1. The rest of my system consists of B+W
M805s augmented bass-wise with JPS Labs Golden Flutes fed electrons by a
McCormack DNA.5 fully modded by SMcAudio. Stands are Atlantis filled with
lead and cabling is JPS Labs Superconductor ICs and LAT speaker biwire speaker
cable. CDP is a Classe CDP.5. No vinyl in my system.
I wanted more dynamics than I was getting with the TLC-1, but I didn't want
to give up transparency and the wide open soundstage I felt I was getting with
the TLC and which seemed to be missing from the other solid state preamps I had
auditioned with my system. When Steve McCormack told me he had some fantastic
upgrades in mind for the TLC, I half-assumed (sort of like half-assed) that my
search would soon end since his mods to the original DNA.5 Deluxe were
absolutely stunning. Well, the SMcAudio TLC-1 didn't wow me. Dynamics came in
and soundstage shrunk with much less neutral tonality.
I read a certain review of a strange product called an Audio Prism Mantissa
posted by a guy who had a system not dissimilar to my own. He had replaced a
McCormack TLC-1 and had obtained just the kind of results I was looking for.
I had been thinking about auditioning an AI Modulus 3A which would require
buying it mail-order since there is no local dealer. I found out Galen Carol
(San Anton(e), TexAss) was a dealer of both, and knowing of his impeccable
reputation, gave him a call. Lets just say, to keep things on point, Galen was
very positive on the AP Mantissa without specifically saying it was better than
the AI.
I have now had the Mantissa in my system for five weeks. It has had the same
effect Robert McNeice cites below. My small B+W M805s sound as if they were inbred with a pair of good electrostats, combining the best of both-the imaging of so-called minimonitors with the more realistic image size and superior transparency of electrostats. How can this be? Galen attributes it to tube-related phase shift. I don't care what causes it-it's there and I like it. Soundstage width is just as wide as it was before (it was *very* wide) but now I have real depth as well. The dynamics I wanted are abundant. I was looking for macrodynamics, but I now realize it was better microdynamics that I needed. The difference, once you realize you were missing it, is not optional.
The Mantissa now comes with NOS JAN Philips 6922s and 12AU7s. I liked the combo
but couldn't resist putting in Tungsram 6DJ8s and Mullard ECC82s at the
suggestion of Kevin Deal of Upscale Audio (a great guy to deal with) after
three weeks of listening to the stock tubes. I could be very happy with either
combo and will probably be happier with others later.
I had no trouble whatsoever getting used to the dual stepped attenuators.
Reality is (at this stage of evolution) that anything other than attenuators
(one resistor in the signal path at any given time) involves a compromise that
I'm not willing to make, so remote-be-damned. I also was prepared for something
of a visual let-down based on photographs, but as it turns out, the real-life
Mantissa is pretty cool looking in black. The power supply is built like a brick
and attaches to the linestage with a garden hose-like cable. But all of this
build quality stuff is meaningless without fantastic sound, and that's what you
I'll end with two brief examples of what the Mantissa can do. I had always
thought Bill Frisell's "Nashville" sounded a bit dry on CD, not as rich
harmonically as his subsequent "gone, just like a train". When I had about thirty hours of playing time on the Mantissa, I put "Nashville" into the cd
tray. Two minutes into it, I put down my magazine and realized I was hearing "Nashville" for the first time. It sounded just as harmonically rich and vibrant as "gone, just like a train. "[G]one, just like a train" doesn't sound richer at all, let alone "syruppy" and yet the formerly "dry" "Nashville" now sounds just a good, if not better. How can this be? Must be tube related phase shift. The other example is "Somethin' Else" with Cannonball Adderly and Miles Davis. I swear, I never understood what made this recording so special as to warrant "classic" status. Then I heard it for the first time, literally, with the Mantissa. The aformentioned microdynamics made the recording sound alive and vibrant in a way I would have never suspected was attributable to my old linestage's deficiencies.
One caveat: I did not audition any other similarly priced tubed preamps in my
system. I don't claim that the Mantissa sounds better than any of it's
competition, in my system or yours. I only know how IT sounds in my system.
Your mileage may vary.

[Mar 05, 1999]
Robert McNeice
an Audio Enthusiast

Audio Prism is probably better known as the manufacturer of those green pens for your CD's, the backlight CD thingy and a line of very high quality power line products, among other things. They also make an incredible preamp and some hulking $15000 tube monoblocks.
My System: currently consists of McCormack DNA.5 Deluxe amp, TLC-1 passive preamp (review posted for both), Cal Labs DX2 CD, customized VPI Aries turntable, Grado Platinum cartridge on an AQ PT6 arm, Audio Innovations phono preamp, Belden 89259 DIY interconnects, Scanspeak 717 DIY speakers.

Past Reviews: My review of the TLC-1 said it had great clerity and detail but lacked energy. This is fairly common on passive preamps and led me to look for something to bring the energy back while keeping that clarity and detail. Well naturally, tubes came to mind. I auditioned a few but didn't find what I was looking for. They all seemed to be missing one element or another. The list includes CJ PV12, ARC LS9 and LS15, BAT VK3i and VK5i, Melos SHA Gold, Classe CP60, VTL 2.5. I then heard the Audio Prism Mantissa and couldn't believe what it brought to the table.

Results: Let's just say it handily beat out all of the others within the context of their demo's. The only exception was the BAT VK5i, which was demo'ed with the new Wilson $30,000 speakers, Wadia CD and BAT tubed monoblocks with cables the size of my arm. Completely out of perspective with my system, but I don't think I would hesitate to put the Mantissa in place of the Bat here. Basically, I can't conceive of going back to the TLC-1 after having the Mantissa in my system. Mates incredibly well with the DNA .5 Deluxe amp.

The Sound: definitely natural, quiet and non fatiguing, extended highs, solid bass (if not completely down to the bottom in my system), soundstaging well beyond the speaker positions, depth of field that the TLC-1 can't possibly recreate (tubes really are magical), mids that are truly rich and full (again that tube specialty thing). But most of all, the instruments were more definitely in their own space. Room acoustics on purist recordings were amazing to behold. I've only heard this kind presence before on electrostatic Martin Logan speakers. My speakers were in awe of themselves!

The Build: Top quality parts here. The case is heavy guage aluminum. The controls are solid and use the detent-separate resistors approach rather than a continuous pot. The inside is impressive with 4 tubes. Outboard power supply is heavy (@15 lbs) and probably contributes much to the quality of the sound.

The Drawbacks: It's dual mono so it has 2 volume controls - 1 for left and 1 for right. Actually, once you get used to it it's pretty cool and very easy to get the balance right. The design is a bit retro with an arched top and a burnished gold finish. No phono section; it's a line stage but has a "phono" marking on the selector knob instead of a generic "aux". The back panel RCA layout is different, but makes sense considering the dual mono design. Not advertised, not widely reviewed, no used units on the used market (possibly due to the fact that most owners wouldn't give up the Mantissa considering the trouncing it gives the similarly priced competition). However, my unit came off a demo shelf and was made in April '96. I called the company and they will update it to the current version (better caps, power supply upgrade and a few other minor changes) for a very nominal amount. Audio Prism is solid, due to their accessories business, and is gearing up production due to increased demand.

5 STARS going to 6 - it's a sleeper and you can still get in before the word gets out.

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