Spectral DMC 6 Preamp

American Audiophile

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Aug 17, 2010
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Stuart, FL
This review deals with one of the genesis products from Spectral in 1986. This was the second preamp produced, with the DMC 5 being the first. This is a ultra wideband preamp extending to 1.2 MHz. and is one of those empirical designs from the gifted minds at Spectral. This was and remains one of high end audios benchmark products of the past century.

The DMC 6 preamp is powered by a stand alone power supply attached to the main preamp via embilical cord. This was the companion preamp to the DMA 50 and DMA 80 power amp. Finished in a beautiful soft silver front that is quarter inch thick. The all steel chassis is robustly built and has a black textured finish. The rear panel supports gold plated RCA's attached to the chassis itself, nice touch there. The gold plated circuit board is a work of art in itself. very well laid out and using parts of very high quality. Sealed pots for volume and balance control. This is no doubt a serious preamplifier for the discriminating audiophile.

The separate power supply is a hefty item, which should be placed as far from the preamp as the embilical cord will allow. Another nice touch there, to make sure that no transformer interaction can degrade the musical signal.

On the front panel the controls are from left to right;

Input Select: Tuner/CD/Phono/Aux/Tape
Record Select: Tuner/CD/Off/Phono/Aux
Mode: Left/Right/Stereo/Reverse/Mute
Output: which is the Volume Control
Balance: Output to left and right channels.

All these controls are of high quality and have that solid yet silky feel to them in keeping with the status of Spectral and their products.

The all important on board phono section, which is the high light of this preamp is well thought out and a joy to use and hear.

With the preamp facing you and top cover removed.
On the left hand side is the phono stages with dip switches
marked 800/100/30/10. setting the desired dip sw to (on)
loads the stage.They are not addative so select only one.
If 47K for MM is desired than select none(all off).
Now three inches to the right of said dip sw is the gain
potentiometer 0-100. use a small screwdriver to set the
gain in relation to the main volume control. Remember there are two dip switches and two gain control pots, one for each channel, so be sure to set both of them.Mine sets at 800 ohm load and 50% gain for Denon DL 301 MKII.

This is one of the finest phono sections I have heard in a very long time, equal to the Klyne SK5A if not exceeding it by a slim margin. In fact not many stand alone phono preamps can match the Spectral DMC 6.

Listed Below is the music used for the evaluation:

LP Playback:

Bob James - Hands Down (Columbia FC 38067)
Hiroshima - Self Titled - (Arista MFSL1-525)
John Coltrane - Blue Train - (Blue Note BST 81577)
Wes Montgomery - Bumpin' - (Verve V6-8625)
Rickie Lee Jones - Self Titled - (Warner BSK 3296)
Wynton Marsalis - Live Blues Alley - (Columbia PC2-40675)
Eric Gale - Forecast - (KUDU Records KU 11)(CTI Records)
Kenny Burrell & Grover Washington Jr - (Blue Note BT 85106)
Earl Klugh - Finger Painting - (Blue Note MFSL 1-025)
Larry Carlton - Friends - (Warner 23834-1)
Sadao Watanabe - Autumn Blow - (Inner City IC 6064)
Doobie Brothers - Minute by Minute - (Warner BSK 3193)
Santana - Zebop - (Columbia FC37158)
Pat Metheny Group - American Garage - (ECM 1-1155)
Frederick Fennel - Cleveland Symphonic Winds - (Telarc 5038)
Paul Desmond/Jim Hall - Complete Recordings - Mosaic(MR6-120)
Time Out - Dave Brubeck Quartet (Columbia CS 8192)
Paul Desmond - Self Titled (Artist House AH - 2)
Ahmad Jamal - But Not For Me - Argo LPS 628
Bill Evans - At The Montreux Jazz Festival - Verve V6-8762
Bill Evans - At Montreux II - CTI 6004
Sunken Cathedral - American Gramophone - AG 361
No Bass Hit - Concord Jazz Label - CJ-97
Oscar Peterson - Night Train - Verve V-6 8538
Gerry Mulligan Reunion Chet Baket - Pacific Jazz ST 90061
Bill Charlap - New York Trio Stardust - Venus VHJD 22
Michael Garson - Serendipty - Reference Recording RR20
Bill Charlap - Things We Did Last Summer - Venus TKJV19111
Ahmad Jamal - Extensions - Argo 758
Tommy Flanagan - Plays Harold Arlen - Inner City IC 1071
Jazz At The Pawnshop - Proprius - 7778-79
Barry Harris - At The Jazz Workshop - Riverside RLP-1177
Adam Makowicz - The Name Is Makowicz - Sheffield Labs #21

CD Playback:

Ben Webster At The Renaissance (Contemporary Records OJCCD-390-2)
The Royal Ballet Gala Performances (Classic Compact Discs CDSCD 6065)
Jurassic Park Motion Picture Soundtrack (MCAD 10859)
We Get Requests - The Oscar Peterson Trio (Verve 810047-2)
You Won't Forget Me - Shirley Horn (Verve 847482-2)
On Every Street - Dire Straits (Warner Brothers 26680-2)
Trio Jeepy - Branford Marsalis (Columbia CK44199)
Paris Jazz Concert - Louis Armstrong (RTE 1001-2)
Braveheart Motion Picture Soundtrack - London Symphony Orchestra (London LC0171)
Patriot Games Motion Picture Soundtrack (RCA 07863 66051-2)
Highlights From The Plugged Nickel - Miles Davis (Columbia CK 67377)
Private Investigations Best Of Dire Straits (HDCD) - Dire Straits (Warner Bros 49891-2)
Straight Up - Bob James Trio (Warner Bros 945956-2)
Land Of Giants - McCoy Tyner (Telarc 83576)
New York Reunion - McCoy Tyner (Chesky 5173324)
Gladiator Motion Picture Soundtrack(Decca 2894670942)
Copland - Appalachian Spring (Telarc CD 80078)
Frederick Fennell - Holst Suites (Telarc 80038)
Tchaikovsky - 1812 Overture (Telarc 80041)
John Williams - American Journey (Sony 89364)
Bizet - Carmen (Telarc 80048)
Live At Sweet Basil - McCoy Tyner Trio (Evidence ECD 22106-2)
Paul Desmond & The Modern Jazz Quartet - Red Baron JK57337
Jimmy Smith - The Unpredictable - Verve 8230308-2
Dexter Gordon - Our Man In Paris - Blue Note 7 46394 2
Mike Garson - Jazz Hat - Reference Recording RR 114
Bill Evans - Live In 1975 Switzerland - Gambit 69232
Bud Powell - Essen Jazz Festival - 1201Music-1QGN9
Cannonball Adderley - Know What I Mean - Riverside OJCCD105
Bill Evans - Ronnie Scotts 1980 - Gambit 69242
Tommy Flanagan - Over C,s - Prestige - OJCCD 1033-2
Ahmad Jamal - Chicago Revisited - Telarc CD 83327

Turntable of reference is the VPI HW19 MKIV with Audioquest Tonearm with Denon DL 301 MKII MC phono cartridge. The CD player of reference is the Audio Analogue Paganini.

Installation is as simle as it gets. Top row of RCA,s are for left channel and bottom row for right channel. Has grounding post for the turntable. The embilical cord connection on back panel as well. Locate the separate power supply as far from the preamp as practical for your set up. Power supply has IEC connector so use a very good power cord there.

When powered on a light green LED illuminates in the middle of the front face plate to indicate operation. There is no on/off switch like all preamps of this caliber the Spectral DMC 6 is to be powered on continously. The power amp is the Spectral DMA 50.

There are indeed today very few preamps with on board phono sections and this is the configuartion that appeals to me. I have tried many out board phono sections, but none of them appeal to me, more cables to run and another power source in the chain to deal with. But that is my preference.

Once installed let the Spectral run 24/7 before any critical listening and evaluation took place. In the days to the run up for evaluation it did not dissappoint.

By the above play list a wide genre of music was played in both LP and CD format. Of course being the dyed in the wool analog maven that I am, vinyl was first up for the evaluation.

Could not be impressed more with the Spectral DMC 6 in vinyl playback. This phono section is truly stellar as one would expect from Keith Johnson. Its ability to delver the music with a depth, clarity and outright emotion to be able to get oneself totally immersed in the music. The way it has the ability to seek out the layers of the musical experience and to retrieve those signals and pass them through to the listener is a joy not often encountered. Prior to this I thought the Klyne SK5A preamp with its phono section was the best I had heard. However the Spectral DMC 6 is clearly its equal if not in my opinion surpassing the Klyne by a small margin. Not to disparage the Klyne at all, but the DMC 6 is extraordinarily one of the finest preamps to pass through here in many,many years.

Of course it excels at audiophile recordings from Reference Recordings, Telarc, Speaker Lab, Angel, MoFi Sheffield Labs and other audiophile recordings. That is expected of a preamp of this caliber. However to get much the same with consumer grade vinyl is remarkable. So many times with records that I was famaliar with in my library that had been played many times, using the DMC 6 was like hearing them for the first time and to a depth and experience I thought was not in those grooves. Over the years I had missed a lot in those records, where other preamps did not extract the most from those grooves. Big time impressed there. It must be menetioned here that the phono section is graveyard quiet and I do mean quiet, the music appears from a solid black background. For all practical purposes this is all an analog maven could wish for in a phono section.

This preamp produced just some three years into the then CD revolution has a dedicated CD input, something very uncommon for the time as most preamps did not have a dedicated CD input, most went with the Aux input for CD playback. However common now in preamps at this period of time it was not. I have no idea as to what was done to the CD side of this preamp, but whatever was decided on is a big plus here. The Audio Analogue Paganini CDP has never sounded better than with the Spectral DMC 6. While it falls a little short in overall sonics when compared to the phono section, it is nonetheless another joy discovered in the evaluation. I am not a big CD listener by any means and my LP library outstrips my CD library by at least a ten to one maragin, if not more. However listening to CD playback through the DMC 6 is just spectacular for that medium. I found myself towards the end of the evaluation listening to one CD after another, something I have never done. I usually pop one in give it a listen, then is cataloged to the library. and in most cases not listen to again for quite sometime. Although there are a few in my rotation and I do mean a few. The Spectral has a way of taking the edge off CD playback and giving a solid musical presenation. Of course of all things being equal the CD itself must be properly recorded to maximize the sonic signature of the DMC 6. But with all things considered, this playback has to be heard to be believed and that put a smile on this rather jaded audiophile of way to many years in this hobby. For once a CD playback I can live with, for that's out there for yours truly.

When this preamp broke onto the market it was priced at $2,495.00 a hefty sum indeed for 1986. In todays dollars that equates to $4,995.00. Although some 24 years in service, in my opinion still ranks as one of the best audiophile preamps I have had the pleasure to own and hear. One can hurl all the audiophile positive adjectives and still come up short on what this preamp is capable of, even by todays standards.

For some odd reason used prices on the Spectral DMC 6 are quite soft in my opinion, why I have no idea. For instance a Klyne SK5A will command a price of $1,200.00 or more same of the Coda 01p. Threshold FET 10 is in same range of the above. Many of the Levinson and Krell preamps will be in the $1,500.00 range or more. While the used average price of the Spectral DMC 6 is only about $700.00. However the trick here is to find one, they very seldom come up for sale and when they do they are snapped up at damn near light speed - so what does that tell you?

A world class preamp for that kind of money is an outright gift by any standard. Plus Spectral remains in business so parts and service remain available, a valid point in considering any piece of pre owned audio gear. It was often said that the Coda 01p is the Rolex of preamps, that being said then the Spectral DMC 6 ranks as the Cartier of preamps.

If needing a sterling preamp for your system, look no further, prices will not remain this depressed very long on the Spectral DMC 6. This should be on your short lists of preamps and a wake up call.
 

Gregadd

WBF Founding Member
Apr 20, 2010
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I'll comment on your review later. One of the things I like about reviews like this is the discography. I find some great treasures in soundtracks.
 

ack

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May 6, 2010
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Yes it is. And the 'DM' designation in their amps and preamps is after his initials. BTW, anyone remember the Entec subs? Also designed by Martin, and I still have an original SW-5 from ca 1985 in perfect condition, but did have to replace the surround after 15 yrs or so.
 

mullard88

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Jun 5, 2010
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I remember the Entec subwoofers. I went through a few pairs of the single driver and double driver units of those Entec subwoofers. I was so pleased with them that I also installed them in my video system and excercise room. I even gave them to my brother and sister as gifts. I changed the transformers to toroidal ones to enhance the outputs but burned the boards. All my Entec subwoofers are dead now. Damian designed a subwoofer for Element some ten years ago and this is what I am currently using with all my speakers.
 

ack

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May 6, 2010
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Huh... never heard of it. Would you have a picture? For old times' sake, I'll post some pics of the Entec at some point... What a piece of work, but doesn't really sound as musical as my current REL.
 

DaveSpectral

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Aug 30, 2010
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Near Chicago
If needing a sterling preamp for your system, look no further, prices will not remain this depressed very long on the Spectral DMC 6. This should be on your short lists of preamps and a wake up call.
Thank you so much for this! This is such a rare preamp, I can never find anything about it on the Inet, except for what I wrote. LOL I have had the term Spectral, and Threshold in my Google alerts for a few days, and this thread jumped up.

I am also a very happy owner of a DMC-6. (Series two, I think it says Delta inside - That is not mine in my avatar) About 12 years ago, I paid $1,350 for mine, and was told it went for $2,850 list. When I first heard the phono section, I was absolutely SHOCKED. It is almost as quiet as the high-level, (But I'm using it with HO MC cart) I went to the KAB site, used their recommended gain chart, balanced it to within 1/50th of a dB with LMS, (you can magnify the graphs on the monitor to do that) and I can not believe how stunning it sounds.

I read somewhere that with this preamp, they do something different: They put some section of it ahead of another section. I just can't remember what it was, but it increases the S/N ratio of the phono. It's a very fine looking piece, and it looks like the same knobs as the Threshold Fet-9 and 10. As for price, I have been tracking this and Threshold stuff for a few years. I saw one go for as low as $650, when I started to do so. I saw one a few months ago, go for closer to $800. I think the thing holding the price down is that people don't really know what it is, and even with their new gear, Spectral doesn't advertise much. I don't think they are interested in market share. LOL

If this picture upload works, the pic here is someone else's DMC-6.

I'll start another thread, or p.m. you about a couple things. I didn't want to curtail this thread. Suffice it to say, if one pays about $700 for this......it's like robbing a bank!
 

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American Audiophile

New Member
Aug 17, 2010
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Stuart, FL
Dave - Thanks for the kind words on the review and for posting these additional pics, which I have added to my file and future knowledge of the DMC 6. For analog mavens such as myself
and you as well, the phono section is just mind boggling on its ability to retrieve information from the cartridge. Over some 53 years in this hobby I believe this is the finest phono section
I have heard. There are many more preamps out there with phono, but none come to mind that have this prowess in phono. Rest of the inputs are very good as well including the CD input.
I know that the Audio Analogue Paganini CDP has never sounded better. Thanks for responding to this thread, much appreciated.
 

DaveSpectral

Well-Known Member
Aug 30, 2010
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388
Near Chicago
Anytime! Glad you appreciate it. I'm going to start a separate thread about Spectral vs. Threshold phono sections. Please look out for it, because if you did a review like this one, it sounds like you would be a big help in my decision. I'm thinking of buying a Fet-9 or Fet-10, but I'll discuss that (vs. Spectral) on the other post.
 

American Audiophile

New Member
Aug 17, 2010
36
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0
Stuart, FL
Anytime! Glad you appreciate it. I'm going to start a separate thread about Spectral vs. Threshold phono sections. Please look out for it, because if you did a review like this one, it sounds like you would be a big help in my decision. I'm thinking of buying a Fet-9 or Fet-10, but I'll discuss that (vs. Spectral) on the other post.

If interested in a FET 9 I have a black face model with box,manual and accessory package. As close to new as one will ever find.
 

jadis

Well-Known Member
Apr 28, 2010
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Yes it is. And the 'DM' designation in their amps and preamps is after his initials. BTW, anyone remember the Entec subs? Also designed by Martin, and I still have an original SW-5 from ca 1985 in perfect condition, but did have to replace the surround after 15 yrs or so.

Hi Ack,

Am posting on behalf of my good buddy mullard88 a picture of the latest subwoofer design by Demian Martin, it's called Element.

 

jadis

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Apr 28, 2010
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ack

VIP/Donor & WBF Founding Member
May 6, 2010
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1audio

Well-Known Member
Sep 17, 2010
31
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353
SF Bay Area
I thought I should clear up some of the history of the Spectral preamps here. I designed all of the Spectral preamps through the DMC-20. Keith O Johnson took over around that time. The first Spectral preamp was the MS-1, a true kitchen table product. We built 20 or so of those. The DMC-10 was the first full production preamp. The DMC-5 and DMC-6 were value engineered versions of the DMC-10. Perhaps the key differentiator in the designs was the combination of low noise and wide bandwidth. The unusual phono implementation mentioned was actually this: the phono section has about 40 db gain typical for a moving magnet phono section. However it has extremely low noise, typically around 3 nV per root Hz, appropriate for a moving coil input. What I did was add more gain in the high level section, 20-35 dB, to make up for the low levels from the moving coil cartridge. This also gives an enormous dynamic range and very high overload for a phono section. To match the levels of the phono section the high level inputs are all padded down. By keeping the stage gain lower I could maximize the bandwidth of the system.

There aren't a lot of differences in the circuitry between the DMC-10 and the DMC-5 and DMC-6. The DMC-5 has an internal power supply, which brings some hum we never really got rid of. The later DMC-10 versions got a cascoded input, that can be retrofitted to the DMC-5 and the DMC-6. Crosby Audio had a substantial mod for the DMC-10 and the DMA-50 and DMA-100. Only a handful were ever modified and they can't ever return to Spectral, having been substantially changed.

The basic circuitry has evolved and I don't know anything about the current Spectral products. I used a similar circuit with a lot of enhancements the the NuForce P-9.
 

ack

VIP/Donor & WBF Founding Member
May 6, 2010
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Boston, MA
Demian (I assume),

this is great stuff to know about, and good to have you here. I gotta tell you, I still enjoy my Entec SW-5 (which I last listened to just 3 weeks ago) as I did back in ~1985, despite the fact that, by today's standards, the box is somewhat resonant! Great stuff!

So any truth to the music server involvement? Any details on that?

Peter

PS: perhaps I should start a new thread
 

1audio

Well-Known Member
Sep 17, 2010
31
2
353
SF Bay Area
Peter:
I'm pleased you are still enjoying the SW-5. it would be fun to update that technology but a lot of work and i have many other things tugging at my time.
the auraliti player did start as an idle speculation on my part. I created the current version. If you have questions about the player we should start a new thread since it has no connection to Spectral.
 

1audio

Well-Known Member
Sep 17, 2010
31
2
353
SF Bay Area
I consult for all three companies and a few others. Monster Cable keeps me very busy, the others keep me sane.
 

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