SpectralDMA-50usedSpectral DMA-50 Amplifier, Made in the USA**Please click here to check out our newly launched SkyFi Audio website with additional items for sale**Very simple design and operation, yet built to the highest quality standards we have ever see...1799.00

Spectral DMA-50 Amplifier, Made in the USA

Listing ID: lis9c501 Classified 
 Listed  · 350 Views
Time Left:4 Days
New Retail Price: $2,999.00


Buy It NowMake Offer
Payment methodsVisa cardMastercard cardAmex cardDisc cardPaypal card

Contact seller after sale to pay viaCertified check, Personal check, Wire Transfer or Express Checkout

Ships fromRidgewood, NJ, 07450
Ships toUnited States
Package dimensions?" × ?" × ?" (50.0 lbs.)
Shipping carrierUPS
Shipping cost$75.00
Original accessoriesBox
Agon miniAverageResearch Pricing

**Please click here to check out our newly launched SkyFi Audio website with additional items for sale**

Very simple design and operation, yet built to the highest quality standards we have ever seen.  I'm talking laboratory instrument quality with regards to component selection, layout, and design. 

One of the few amps worthy of interior shots and a plexiglass cover.  Notice the gold plated circuit board and the methodical component placement and wiring paths.  

Simple operation containing only the most critical adjustments. Just power and mono/stereo operation. 

Great condition with no significant scratches or dents.  Tested fully in our lab and woking to specification.  

See the matching Spectral DMC-10 preamp we're selling for an amazing combo. 

Comes inoriginal box with foam interior packing.  Outside of box is a bit worn but sturdy.  

Design Brief

This is the first amplifier to combine quickness, speed and brutality with meticulous design and performance detailing. Its miniturization is functional as its dense packed component arrangement assures fast in-phase response with precision timing along all circuit paths. Circuits feature quick responding bi-polar, J-fet, and large area enhancement mode amplifying devices, all cleverly arranged to make fast linear gain stages. Each channel has four of these, and each stage "is capable of very high drive current, overvoltage, and rapid charge sweep. Such high energy capability makes the following stage and load respond quickly without charge memory overhang from previous waveform events. Because of this, the DMA-50 responds in 0.0000001 second to overloads, cable reflections and other real system requirements. Moreover, this quickness is backed up by an 18 amp. 1,000 volt per microsecond output capability when needed. Hence with so much dynamic headroom, the DMA-50 will reproduce a DC to one megaHertz output signal virtually stress free. 

This power, speed and quick recovery foundation sets the stage for very subtle and transparent reproduction. To do this, many design features from microwave technology and master recording electronics experience are applied. The most important ones eliminate subtle but cold, grainy, and often "skidderish" solid state sonics. Also, the amplifier is made unquestionably stable for all combinations of voltage, current, load, cables and wave time history conditions occurring anywhere in the circuitry. Unfortunately, in practice, all amplifying devices change characteristics with variations of these conditions. Vacuum tubes do this smoothly however, for the DMA-50, the well known abrupt solid state junction behavior is rounded and linearized with very carefully thought out and chosen interstage canponents. Gain stages then respond tube-like with an inherent low distortion, a more symmetrical voltage slew and near glitch free overload recovery. With less distortion coverup needed, feedback requirements then become less stringent thereby preventing internal overdrive problems that create the "kinks" and "funny stuff" all too prevalent with large complex designs. 

Again miniturization pays off by allowing an almost inductance free grounding scheme and making frequency compensated dividers along the very small feedback paths. As a sideline, these very critical parts are oxide free exotic. metal construction yielding electrical accuracies only the most sophisticated test equiptment obtainable can measure. Such features improve sonics and assure absolute solid defined performance for any practical combination of loads and cables. Additional interference rejection occurs from a 50 mHz cascade front end gain stage giving isolation between the inner amplifier signals and the outside world of cables, preamplifiers and loads. Indeed, inner signals of many large complex high feedback amplifiers are extraordinarily distorted and harmonic rich. These tend to ripple through from stage to stage wi thin and often resurface at one or more connectors or grounds. Different cables and loads can alter these ripple through interference wave shapes thereby creating different sonics either at the amplifier or other equipment receiving this energy

The inherently linear and isolated construction of the DMA-50 eliminates these distorted currents and the resultant interconnect dependancy. Note that vacuum tube circuits inherently perform this isolation nicely. However, the cascade circuit is much faster and works well into radio and digital sampling harmonic frequencies. Those interferences near the audio range are well within the easy range of the amplifier and are passed through without consequence. Those above, which might cause subtle intermodulation noises, are common mode rejected by the fast input circuit. Hence, filters are eliminated. These and many other considerations result in unprecedented musical accuracy and unchanging stability, and as seen here, the DMA-50 performs flawlessly well beyond every conventional specification. 




@ 8 ohms = 80 WRMS @ 4 Ohms = 120 WRMS 


OUTPUT POWER P.K. @ 10% Duty Cycle 


@ 8 ohms = 140 Watts @ 4 ohms = 200 Watts 

BRIDGED 450 Watts 260 Watts

OUPUT CURRENT: Limited to 18A Peak 

DISTORTION: Less than .1% fran D.C. to 100 KHz 'IYPica11 y .006% @ 80 WRMS / 8 ohms

BANDWIDTH: D.C. to 1.2 MHz - 3db 

RISE TIME: Less than 300 nanoseconds 

SETTLING TIME: 500 nanoseconds

SLEW RATE: 1,000 volts/microsecond


GAIN FACTOR: 25 db stereo, 32 db bridged

INPUT SENSITIVITY: 1.2 VRMS for 80 WRMS output into 8 ohms

SIGNAL TO NOISE: 90db unweighted 



DIMENSIONS: 2.5 H x 19 W x 14 D inches



This item will be professionally packaged and insured for safe transit to your home. 

Please click here for detailed specifics regarding our specialized packing process that separates us from the rest.

If we don’t have the original manufacture's packaging, we use heavy duty double ply corrugated boxes with Instapak expanding foam custom inserts.  In many cases this has proven to be better than the original packaging.  We also use high quality fiber reinforced tape to seal our packages.  Lightweight items will be bubble wrapped and shipped in a high-quality box. 

This item is available for pickup in Glen Rock NJ.

NJ Residents or anyone picking up without a resale certificate will need to pay NJ Sales Tax.

Use the Buy It Now button and we will cover the PayPal fees.

Thanks for looking and be sure to call or text 201.879.0000 with any questions. 

Please also click here to visit our Audiogon store to see the rest of the items we have for sale.



SkyFi Audio is a small startup business specializing in the purchase, reconditioning, and reselling of select high-end audio equipment.  We only buy equipment the we admire and are passionate about. No mid-fi, no gimmicks, no junk. 

Each piece of equipment is cosmetically restored and fully tested in our well-equipped lab by an engineer with 30+ years of experience in the HiFi world. If it does not meet or exceed the original manufactures specifications, it will not be sold.  We are very selective about the equipment we purchase, focusing on mostly analog, high-build quality, American, and European built units.

Through our sister company, which is an authorized dealer for McIntosh, Audio Research, Sonus Faber, ClearAudio, Pro-Ject Audio Systems, and Sony ES, we have access to OEM parts, service, and support.  If you are local and looking for new equipment from the above-mentioned manufacturers, please drop us a line as we can arrange both sales and professional installation in the tri-state area.


We do not accept or review any offers that do not go through the official Audiogon system. We have too many items for sale and it’s nearly impossible to keep track of offers outside of the official system. Please don’t message, email, or text any offers. 

If you do not see a “Make an Offer” button, it means we are not considering any offers on that item.   


We prefer working through PayPal which allows you to use a credit card or bank transfer. We do not charge extra for any payment fees if you purchase the item at the asking price.  You can also send us a personal check (which will need to clear before shipping), certified check, money order, or wire transfer. International clients without access to PayPal should use a bank wire transfer. 

If you are picking up an item we do not accept PayPal.  You must pay in person with cash, certified or bank check, or wire transfer.  If you make a PayPal payment and are picking up the item, it will be returned. 


We accept trade-ins of equal or lesser value under certain conditions.  Simply ask and let us know the exact model, condition, and the accessories that are included (such as the original box, remote, cables, manual, etc.).  We will only consider high-end equipment from mainstream manufacturers such as McIntosh, Mark Levinson, Audio Research, Krell, etc. and will typically pass on displays, projectors, receivers, dated surround processors, and mid-fi equipment of any type.  We will offer a fair value for your equipment, but keep in mind we are running a business and will need to be able to resell the equipment at a profit after investing a great deal of time and resources in testing, certifying, repairing, cleaning, and packaging the incoming equipment.  If you are looking for top dollar we suggest attempting to sell it directly to an end user on your own.

SELL US YOUR GEAR (Working or Broken)

We will also purchase your used or broken gear and arrange pickup if you are in our local market. Just drop us a note for a quote but be sure to include the condition and what is included. 

HOW TO VISIT US                                                                                                        

We are currently operating from a residence in Ridgewood, NJ.  You are welcome to make an appointment if there is a piece of equipment you would like to see in operation before or after purchase.  We have a well-equipped, dedicated listening room with tons of equipment of all makes and models.  We are not a store, so please don’t make an appointment if you are just curious as to how a speaker or piece of equipment sounds.  In essence, no tire kickers please.

You can call or text 201.879.0000 with any questions or to schedule an appointment.  We can also arrange to install, calibrate, and tune the gear in your listening room if you are local to the area.  This is super useful when purchasing large speakers or heavy amplifiers.  It is also great for ensuring your new turntable is setup correctly in its final resting place.  

Thanks for looking and please click here if you would like to receive a list of the equipment we receive from time to time.  We promise not to bombard you with junk email.   


No questions have been asked about this item.

Ask the seller a public question

You must log in to ask a question.

Return Policy
Return Window

Returns are not accepted on this item.


member since December 2000

SkyFi Audio, LLC  Verified Dealer

Last 12 months

13 Watchers