Spectral DMA-90

[ack]

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...

 

[Addicted to hifi]

Very nice amplifier.

 

[TooCool4]

Nice, Cool.

 

[ack]

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]

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?

 

[ack]

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.

 

[kennyb123]

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.

 

[marty]

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.

 

[kennyb123]

I was just browsing and came across this listing. I have no affiliation with the seller.

Spectra DMA-90 High Resolution Amplifier, Complete And Like New Set

It's rare to find a DMA-90 in a complete set including the box and manual that looks and works this well. Actually most Spectral pieces actually require little to no work when they arrive at SkyFi. A true testament to their build quality, parts selection, and attention to detail. This DMA-90...

skyfiaudio.com

 

[Jon Q]

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

 

[Noctilux]

This is mine DMA 90 Series 2.

 

[Noctilux]

It seems to me that yours is first series.
Which speakers do you drive ?

 

[Tennisdoc40]

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

 

[Sage_R]

@Noctilux or anyone else here, any comments on the DMA-90 series 2 versus the series 1?

The DMA-90 s2 appears more like the DMA-100 in the mosfet choice.

On the vintage Spectral side : have a couple DMA-50’s and I just bought what turned out to be a DMA-90 series 2 - I didn’t know there was a series 2 DMA-90 until I came across these posts.

Loving the DMA-90 S2 so far. It’s a keeper

 

[Noctilux]

@Sage_R
When I had the chance, I compared my DMA90 s2 with a DMA100 s
I preferred the 90. On all parameters I found it superior but especially in the presentation of the mid-low part.
I then replaced the 90 with a 160 a few years later.
And then, after some time again, all my Spectral gear with Boulder.
I hope it can be of help to you
Ciao

 

[Sage_R]

Hi @Noctilux - thanks for the perspective! I was wondering if the DMA-90 s2 might sound similar to a DMA-100s but it doesn’t sound like that is the case. I heard from someone else that some prefer the DMA-90 s1 over the s2… overall there is overwhelming love of the DMA-90 regardless of series.

I have a DMA-250 Series 2 that’s been my main amp in an all spectral setup for little while. I’m comparing these two amps on some high efficiency speakers and the DMA-90 s2 holds its own next to the DMA-250 s2 (which is the stereo version of the DMA-360 series 2).

• DMA-90 s2 feels more nimble across the frequency spectrum (ie. sounds faster)

• DMA-250 s2 sounds a little more “full” across the spectrum, with increased authority.

Have tried both amps with a DMC-30SS s1 and a DMC-30SC. Obvious difference is the significant increase in gain on the SC versus the SS s1. More detailed sound overall on the 30SC but in my limited tests comparing the two- I’m satisfied with both on my high efficiency speakers with a clear edge to the SC. I don’t really go above 50% gain on the SS1 and 40% on the SC.

I’m liking the Berkeley Alpha DAC (series 1) straight into the DMA-90 and the DMA-250. I’m using a Spectral/MIT 2C3D Level 1 rca to connect them and a MIT 2C3D digital AES to connect the Alpha USB and the Alpha DAC. Speaker cable is either a 25 foot run of MH-750 ULII or a 8ft run of Spectral 2C3D level 2.

The 2C3D level 2 sounds “better” (more detailed, more low frequency extension/clarity). But I can only test with this short a run - default is the 25foot cables to get to the rack. I have no issues with the MH-750 Ultralinear II’s in this setup, they sound great. Maybe they take some edge off the DAC going straight into the amp(s). I have not done extensive listening on the level 2’s to know if the increase in detail is a bonus or would become fatiguing in this setup. I suspect I may like adding a preamp with the level 2’s to balance things out more - where the ULII’s balance the sound nicely without the spectral preamp.

I’m eager to try a newer Berkeley (reference s2 or alpha s3) and upgrade my Alpha DAC s1 and usb s1 with the mqa software upgrade and the s2 usb upgrade to see how this improves things.