Spectral DMA-90

ack

VIP/Donor & WBF Founding Member
May 6, 2010
6,775
1,177
580
Boston, MA
Will be using this in my second system soon - no idea how it sounds, but it's got a reputation for being very dynamic and perhaps the best overall of the older slim series... ca 1994, mint condition, runs hot (high bias but not Class A exactly), sliding bias ("utilizes a floating bias current which follows the music signal"), claims to sport a driver stage with a 50MHz bandwidth and J-Fets, 1000V/usec slew rate, 1.5usec settling, ~2MHz output bandwidth, won't _require_ MIT cables but does need a high-current preamp as all the rest (180mA or more). Noticing those stabilization inductors in the output at the speaker terminals (long removed since that design). But of course, that same old Texas Instruments NPD5566 chip, not replaced until the new SV series... I think I am noticing copper foil hugging a couple of transistors in the driver stage; mumetal shielding for the transformers of cource...

dma-90-IMG_4912.JPG

dma-90-IMG_4923.JPG

dma-90-IMG_4921.JPG

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Last edited:

TooCool4

Well-Known Member
Feb 7, 2013
721
590
405
England
Nice, Cool. :cool:
 

ack

VIP/Donor & WBF Founding Member
May 6, 2010
6,775
1,177
580
Boston, MA
Should be good for what I need it for... basically, my second system has been frozen in the '80s save for speakers and cables, and it's time to bring it to the '90s LOL :) - so I will be replacing the Acoustat amp with this DMA-90, a Technics tuner with my current modded Magnum Dynalab Etude (ca 1995 original model, but up to date now), and a CD player with my modded Alpha DAC which also has the latest 3.0 software update from Berkeley. Should be fun, and the current Monitor Audio 2-ways are easy to drive, but I will attenuate the tweeter a bit...
 

leyenda

Well-Known Member
Mar 3, 2011
195
74
413
Minty mint, very nice find. I am a fan of Damian-era Spectral. Have you tried the DMA90 in your main system? How does it compare to latest gen amp?
 
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ack

VIP/Donor & WBF Founding Member
May 6, 2010
6,775
1,177
580
Boston, MA
I did not try it on this system, too light for the speakers. And the amp’s manual bears Johnson’s name. The unit appears to be very lightly used and even the power switch feels pristine. The paint job is still immaculate too.
 
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kennyb123

Well-Known Member
Nov 30, 2012
542
367
375
Kirkland, WA
The unit appears to be very lightly used and even the power switch feels pristine. The paint job is still immaculate too.
It looks almost brand new. Heck of a find. It sound like you will have a heck of a frozen in the 90s system.
 
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marty

Well-Known Member
Apr 20, 2010
2,602
3,012
760
United States
The DMA 90 is one of the greatest sounding amps Spectral amps ever made. I used it's precursor (DMA 50) and then the DMA 90 for nearly a decade many years ago. What was nice back then is there wasn't the mandatory insistence by Spectral that you needed to use a Spectral preamp and networked cables for the DMA 90 to perform well. (It never had the >2M Hz bandwidth of the later amp designs so didn't go into oscillation when used with preamps of another manufacturer. I always used tube preamps with Spectral amps and lived to tell about it! Since most tube preamps rarely had a bandwidth much above 100 KHz, many with low output impedance were a fine match for the DMA 90 as it would be impossible to drive it into oscillation). I loved, loved the DMA 90 and I'll bet you will as well.
 
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kennyb123

Well-Known Member
Nov 30, 2012
542
367
375
Kirkland, WA
I was just browsing and came across this listing. I have no affiliation with the seller.

 

Jon Q

VIP/Donor
Jun 16, 2019
90
41
135
Lisbon
Will be using this in my second system soon - no idea how it sounds, but it's got a reputation for being very dynamic and perhaps the best overall of the older slim series... ca 1994, mint condition, runs hot (high bias but not Class A exactly), sliding bias ("utilizes a floating bias current which follows the music signal"), claims to sport a driver stage with a 50MHz bandwidth and J-Fets, 1000V/usec slew rate, 1.5usec settling, ~2MHz output bandwidth, won't _require_ MIT cables but does need a high-current preamp as all the rest (180mA or more). Noticing those stabilization inductors in the output at the speaker terminals (long removed since that design). But of course, that same old Texas Instruments NPD5566 chip, not replaced until the new SV series... I think I am noticing copper foil hugging a couple of transistors in the driver stage; mumetal shielding for the transformers of cource...

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I had an opportunity to buy two of these units, but I let it go, that day I was very upset with myself.
The copper foil is so that the two transistors have the same possible temperature (thermal pairing). Helps keep the offset (DC output) very low as possible
 
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Tennisdoc40

New Member
Nov 2, 2020
4
1
3
60
I traded my dma 90 in to sky fi audio recently, and that may be the one. If so it was purchased in 1997, with spectral preamp and mit wire. Used for a few years with audio physic speakers and never loudly. Bought a dma 150 9 years ago so it sat in the box , with hope one of my kids would be interested in audio. None of my spectral gear needed service or shut down from heat or load. Tried it one time on friends Maggie’s and it just didn’t have the current to flesh out the bass, though the midrange and treble were fine. Price seems high to me. 3200 new
 

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