DMC 12 experience

Oct 2, 2021
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Recently I bought a DMC 12 preamp. The sound but foremost the resolution is outstanding. Together with the DMC 12 I use a DMA 90 and from time to time a DMA 160 power amp. Although the DMC 12 is extremely satisfying, I realize a very audible noise. Can that noise be an effect of it‘s age? Furthermore while opening the unit I discovered (with shock) that my DMC 12 got some modification at the power section. Does anyone have an exerience with that modification? Again, beside the unexpected noise level the unit plays very fine. Thanks for your help.
 

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Oct 2, 2021
9
3
5
59
Recently I bought a DMC 12 preamp. The sound but foremost the resolution is outstanding. Together with the DMC 12 I use a DMA 90 and from time to time a DMA 160 power amp. Although the DMC 12 is extremely satisfying, I realize a very audible noise. Can that noise be an effect of it‘s age? Furthermore while opening the unit I discovered (with shock) that my DMC 12 got some modification at the power section. Does anyone have an exerience with that modification? Again, beside the unexpected noise level the unit plays very fine. Thanks for your help.
Finally found a gentleman very experienced with all sorts of Spectral Audio gear. He brought my unit back to factory delivery status. Extremely happy now.
 
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TooCool4

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Feb 7, 2013
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Streetlife 1962 how does the DMA 90 compare to the DMA 160 as the DMA 160 is a universal unit?
 
Oct 2, 2021
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Streetlife 1962 how does the DMA 90 compare to the DMA 160 as the DMA 160 is a universal unit?
The basic character I would judge as very comparable, although the 90 sounds slightly softer than the 160, which sounds somehow more precise. The loudspeakers I am using are JBL 4333B monitors.
 

TooCool4

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Feb 7, 2013
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Thanks for the info. I am not familiar with those JBL's.
 

wapehatson

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Jul 26, 2022
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Recently I bought a DMC 12 preamp. The sound but foremost the resolution is outstanding. Together with the DMC 12 I use a DMA 90 and from time to time a DMA 160 power amp. Although the DMC 12 is extremely satisfying, I realize a very audible noise. Can that noise be an effect of it‘s age? Furthermore while opening the unit I discovered (with shock) that my DMC 12 got some modification at the power section. Does anyone have an exerience with that modification? Again, beside the unexpected noise level the unit plays very fine. Thanks for your help.
Hello Streetlife, I am auditioning a Spectral DMC 12 and I am experiencing a similar issue to yours and I wondered how yours was resolved? Mine has a hiss or white noise audible from about 10 feet away. When you mentioned you found someone to look into it was it an age related capacitor issue? I should mention too that I am driving very efficient speakers (99db) that may be why I can hear the noise from a ways away. thanks very much
 
Oct 2, 2021
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Good evening wapehatson,
I live in Germany and here I found a gentleman named Ralf Kassel. He‘s a development engineer for some audio brands and beside that he‘s very experienced with all sorts of Spectral gear. First he removed the strange addition to the power supply of my unit. Then he changed all capacitors and finally he reduced the gain of the unit. He explained to me that lots of preamplifiers of that time had a much higher gain, than todays units. That high gain is not needed with todays sources. After all the corrections he made a complete assessment of the DMC-12 with Audio Precision and Neutrik equipment And documented it. The unit performs now absolutely flawless and as good as at it’s day one. If at the end the reduction of the noise level came from the change of the aged capacitors, or the reduction in gain, or the take out of the unnessesary modification to the power supply is hard to say. I would assume it was a combination of all. I am using also high efficient loudspeakers (JBL 4333B) with the DMC-12 (although not that efficient than yours). Noise is no longer problem to me. I have attached the measurement document and an inside view of my unit.
 

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wapehatson

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Jul 26, 2022
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Good evening wapehatson,
I live in Germany and here I found a gentleman named Ralf Kassel. He‘s a development engineer for some audio brands and beside that he‘s very experienced with all sorts of Spectral gear. First he removed the strange addition to the power supply of my unit. Then he changed all capacitors and finally he reduced the gain of the unit. He explained to me that lots of preamplifiers of that time had a much higher gain, than todays units. That high gain is not needed with todays sources. After all the corrections he made a complete assessment of the DMC-12 with Audio Precision and Neutrik equipment And documented it. The unit performs now absolutely flawless and as good as at it’s day one. If at the end the reduction of the noise level came from the change of the aged capacitors, or the reduction in gain, or the take out of the unnessesary modification to the power supply is hard to say. I would assume it was a combination of all. I am using also high efficient loudspeakers (JBL 4333B) with the DMC-12 (although not that efficient than yours). Noise is no longer problem to me. I have attached the measurement document and an inside view of my unit.
Wonderful Streetlife thanks for your kind reply. it looks like yours has phono too which is an added bonus in my opinion. I've opened the top and tried to adjust the output AND input gain but still I get the hissing noise. Perhaps, if I decide to buy the preamp I need to look into replacing the caps. I do really like how the gear reproduces music. To me, cymbals sound like cymbals, and strings like strings etc. but the hissing noise at low volume listening is distracting.
thanks for sharing the information from Ralf Kassel too. Have a pleasant evening.
 

wapehatson

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Jul 26, 2022
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follow up:
in my case, I was able to reduce hiss by using an RCA to XLR adapter. hiss is still there but less
 

marty

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Apr 20, 2010
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Streetlife 1962 how does the DMA 90 compare to the DMA 160 as the DMA 160 is a universal unit?
I owned a DMA 90. Outstanding amp. If I am not mistaken, the only difference in Spectral's "universal amps" is that they were not DC coupled but had caps at the input to attentuate megahertz high frequencies that might drive the amp into oscillation if one did not use networked interconnect cables such as MIT. As you know, Keith Johnson considered networked MIT (or Spectral) interconnects and Spectral amps a "functional unit" designed to work together. However, Spectral realized that not everyone used MIT cables and offered their universal amps so that others may enjoy them as well. Spectral dealers may offer more relevant information.
 
Oct 2, 2021
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I owned a DMA 90. Outstanding amp. If I am not mistaken, the only difference in Spectral's "universal amps" is that they were not DC coupled but had caps at the input to attentuate megahertz high frequencies that might drive the amp into oscillation if one did not use networked interconnect cables such as MIT. As you know, Keith Johnson considered networked MIT (or Spectral) interconnects and Spectral amps a "functional unit" designed to work together. However, Spectral realized that not everyone used MIT cables and offered their universal amps so that others may enjoy them as well. Spectral dealers may offer more relevant information.
True, same applies to the output, were the DMA-90 and alikes still had that series inductor, later models didn't had any more, so you better used the MIT or Spectral cables in which you found the series inductor.
 

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