NAD 2200 Vintage Amplifier Review

[LTig]

Great deal.

 

[pjug]

The 2200 was NAD's first "power tracker" commutating rail power amplifier. When it came out in the 1980s, it basically re-wrote the high dynamic power game and many other brands followed suit. Prior to the NAD 2200, Hitachi had hit the market 5+ years before (1977) with an even more powerful (200+200@8R continuous and well over 600W dynamic) commutating rail monster, the HMA-8300. I have one of those somewhere in my storeroom- all 24kg of it. It also runs (192V) +/-96V rails with 125V reservoir caps.

Some interesting things about the 2200 amplifier:

It runs the two channels permanently in opposite phase but reverses the polarity at the speaker terminals, makes better use of the power supply.
As such, bridging is really easy and simply sends the same signal to each amplifer.
Having one "negative" speaker terminal at 0V (chassis) and the other "positive" speaker terminal at 0V in stereo operation, caused many of these amplifiers to go up in smoke, especially when people used them with certain Polk SRA speakers which required a L-R crossfeed.
In bridged mono, it delivers well over 1.6Kw short term at 4R...

I have an original 2200 brochure I can dig out and scan on this amplifier as I regarded it as a groundbreaking design at the time if anyone is interested.

Something strange I noticed... some online photos of the back of this amp, and also the service and user manuals show as you describe with the R+ and L- tied to ground. But others, including the photo of amp in this review, show R- grounded. Do you know if NAD made two versions of the 2200 with these differences? It doesn't look like this was part of the modifications that were done.

 

[notsodeadlizard]

And this is just a good budget amplifier from the times when the specifications indicated the worst numbers...

 

[Jungstar]

Ridiculously good! Beats the C320BEE which came out years and years later.

Not if you run the C320BEE as a power amp alone....

 

[SirPaulGerman]

I was offered a Nad 2200 for ok money, however I have a similar amp the Adcom GFA-545 MK2, someone already took good measurements of the Adcom

ADCOM GFA-545 II Review

now which one is better NAD vs Adcom using all the data from both amps

 

[Doodski]

I was offered a Nad 2200 for ok money, however I have a similar amp the Adcom GFA-545 MK2, someone already took good measurements of the Adcom

ADCOM GFA-545 II Review

now which one is better NAD vs Adcom using all the data from both amps

Are we talking before or after MODs and refurbishing? The Adcom takes to MODs veryyywell.

 

[SirPaulGerman]

after mods ?
the plan is to have both recap eventually

 

[Doodski]

after mods ?
the plan is to have both recap eventually

Yes, MODs. The Adcom is very good at taking substantial MODs. Modifications!

 

[SirPaulGerman]

which one is better ?

 

[Doodski]

which one is better ?

It depends on the application. What speakers are you intending to run on the amp?

 

[SirPaulGerman]

Dahlquist M907 loudspeakers

Dahlquist, 3-way acoustic suspension loudspeakers

stereonomono.blogspot.com

those

 

[Doodski]

I am somewhat familiar with the lineage of the Dahlquist DQ10 and maybe the DQ20. So the article is appreciated. The M907 does not appear to be a difficult load for the amp. I would possibly go with the bridgeable solution so there is room for expansion later. The Adcom has the better construction and as I mentioned it can be heavily MODed.
Specifications

Type: Box-style, 3-way acoustic suspension
Drivers
LF : 1 x 10" (254 mm ) cone woofer
MF : 1 x 5" (127 mm) cone midrange
HF : 1 x 1" (25,4 mm ) dome tweeter
Frequency Range: 30 Hz to 24,000 Hz
Sensitivity: 88 dB SPL at 1 m for 2,83 V RMS at 1 kHz
Crossover Frequencies: 400 Hz ; 3,5 kHz
Impedance: 8 Ω nominal (6 Ω minimum)
Recommended Amplifier Power: 40 to 150 watts per channel
Dimensions (H x W x D): 686 x 343 x 276 mm (27" x 13-1/2" x 10-7/8")
Weight: 18,2 kg (40 lbs)

 

[EJ3]

Dahlquist M907 loudspeakers

Dahlquist, 3-way acoustic suspension loudspeakers

stereonomono.blogspot.com

those

I have the M905's (with the xover's refurbished with the same as original microfarad but newer style caps by Peter @ Quirk Audio). They measure 26Hz-20KHz +-2DB (Dahlquist claimed 40Hz-24KHz [I don't recall +-anything]. (I have the stand but have them on my down firing woofers wit some wedges to give them a 3 degree upward tilt. Here is info that I have on the M905's from HiFiClassic:

Dahlquist M-905 Speaker System Review​

Dahlquist M-905
Dahlquist’S first speaker, the DQ-10, was—and still is—an unconventional product: a free-standing system whose drivers are not mounted in the usual box enclosure. Reduction of coloration from box resonances and maintenance of an accurate phase relationship between its drivers are the key features of the DQ-10, which has been on the market for fourteen years and has been acclaimed for its sound quality.
The Dahlquist line has since been expanded to include a number of box-type speakers. Despite their familiar appearance, they have also been designed to be as free as possible of the usual box colorations. Moreover, they have the high sensitivity and linearity needed to reproduce the dynamic range of digital recordings. Typical of Dahlquist’s current line is the new M-905 High Performance Monitor, a moderately priced two-way system.
The walnut-veneered cabinet of the M-905 measures 24 inches high, 13-1/2 inches wide, and 12-1/4 inches deep. The black cloth grille has solid-walnut trim strips and is retained by plastic snaps. Each speaker weighs 35 pounds, and for optimum results they should be mounted on Dahlquist ST-9 stands ($80 a pair), which match the finish of the speakers and support them about 11 inches above the floor, with a backward tilt of 3.5 degrees for optimum coverage of the listening area. Like most free-standing speakers, the M-905 gives its best performance when it is placed at least a foot from the wall and angled slightly inward toward the listener.
The 8-inch woofer of the M-905 is a polyvinyl-acetate-laminated cone operating in a vented enclosure. The outlet of its tuned port is on the front panel of the speaker cabinet. At 2,500 Hz there is a crossover to a 1-inch soft-dome tweeter.
The nominal system impedance is 8 ohms (6 ohms minimum), and the M-905 is recommended for use with amplifiers rated to deliver from 20 to 125 watts per channel. The fiveway binding-post terminals recessed into the rear of the cabinet will accept dual banana plugs. The drivers are protected by individual fuses (0.8 ampere for the tweeter and 3 ampere for the woofer). The system’s sensitivity is rated as 91 dB sound-pressure level (SPL) at 1 meter when the speaker is driven by 1 watt at 1,000 Hz. The rated frequency response is 40 to 24,000 Hz.
Dahlquist refers to the cabinet of the M-905 as an “Un-box” enclosure, likening its construction to that of a violin. The wall panels are of varying thickness, and there is special internal damping and bracing designed to suit the individual characteristics of the drivers in the


system, all to minimize coloration of the sound by the box. The front panel is coated with a black flocking material whose thousands of fibers are electrostatically aligned perpendicular to its surface during application. The flocking and the flush-mounting of the tweeter are said to minimize diffraction from front-panel discontinuities, preserving image focus. Price: $590 a pair. Dahlquist, Dept. SR, 601 Old Wil-lets Path, Hauppauge, NY 11788.

Lab Tests

Preliminary listening tests of the Dahlquist M-905 speakers—in-

stalled on the ST-9 stands, as recommended—revealed a very wide-range and balanced sound whose smoothness and lack of coloration were far beyond what we would have expected from speakers in their price range. In fact, the sound from the M-905’s would be more than acceptable at several times the price. In view of this, we were not too surprised to find that with respect to flatness and freedom from peaks and holes the measured room response was among the best we have encountered.

The close-miked woofer (and port) response was also considera-
bly flatter than we have measured from most speakers, with a very small bass-resonance peak. At the system resonance of 60 Hz, the output was only about 2 dB above its average level in the upper part of the woofer’s range, and even that minor output variation was spread over almost two octaves. When the bass curve was spliced to the room-response measurement, the resulting composite frequency response was flat within about ±2 dB from 26 to 20,000 Hz. The horizontal directivity of the tweeter was only discernible in the room measurement above 10,000 Hz.
We measured the sensitivity of the M-905 as 87 dB SPL, which was lower than the rated 91 dB but still about average for speakers of its size. The difference may have been a result of different test conditions since we used a full-range pink-noise signal while Dahlquist’s rating was made at 1,000 Hz. The system’s minimum impedance was about 4.8 ohms in the 8,000- to 10,000-Hz region, and it measured 7 ohms at 150 to 200 Hz. Its maximum impedance was 28 ohms at 60 Hz, and there was a broad peak of 18 ohms in the vicinity of 1,500 Hz.
We measured the woofer’s distortion with a 4-volt drive level, corresponding to a 90-dB SPL at 1 meter. The distortion was less than 1 percent from 100 Hz down to almost 60 Hz, the effective crossover to the port. Below that crossover the distortion rose to 5 percent at 45 Hz and 9 percent at 35 Hz. In high-power tests with single-cycle tone bursts, the woofer began to sound “hard” at about 350 watts into its 8.5-ohm impedance at 100 Hz. At higher frequencies the amplifier clipped—at outputs of 490 watts at 1.000 Hz and 1,380 watts at 10,000 Hz—before distortion became visible on the acoustic waveform.
Quasi-anechoic FFT measurements showed an overall group-delay variation of about 0.1 millisecond between 4,000 and 20,000 Hz and 0.5 ms between 1,000 and 20.000 Hz, convincing evidence of the attention paid to the phase characteristics of the M-905.
Comments
Although we have often commented on the difficulty of correlating the measured response of a speaker with its sound, the Dahlquist M-905 seems to be an exception: whether you look at its response curves or listen to its sound, it has an extraordinarily smooth, uncolored response. We tried to find some recording that would reveal a weakness, but we soon realized that was a fruitless quest.
As so often happens, there is little in the speaker’s external appearance, or in the manufacturer’s description of its internal design, that would give a clue to its remarkable performance. Many speaker manufacturers claim unique qualities for their creations, which only too often turn out to be “just another speaker.” The M-905, however, really does what Dahlquist says it does, and we were very impressed by the way a two-way speaker with an 8-inch woofer could perform.
The best way to sum up our reaction to the M-905 is to say that it sounded like a far more expensive speaker than it is, especially in the middle and high frequencies. Regardless of its physical size and its price, its sound says, unmistakably, that it is a top-quality speaker.
Excellent with 1 2200 bridged mono (4 ohms) powering each. They claim 8 OHMs but are really 6 OHMS. I also run a semi custom 12' pair of dual 4 OHM voice coil (operating setup is 2 Ohms) subs with an FR of 20Hz to 89Hz using a stereo 2 Ohm operating 2200 (note: running 2 Ohm stereo is highly discouraged by NAD & Peter @ Quirk Audio but I do it anyway). So far, so good

 

[Doodski]

I have the M905's

Are you familiar with Magnat and MB Quart? I was selling them and Dahlquist seemed similar.

 

[EJ3]

Are you familiar with Magnat and MB Quart? I was selling them and Dahlquist seemed similar.

I only know the names.
Fact: Jon Dahlquist was working with Saul Marantz Their collaboration resulted in a speaker that was being transported in their car and stolen when it was broken into. Supposedly a new design that would upend the speaker business in the same way the DQ 10 did.
Un proven to me (classified as rumor in my mind) Then, apparently, Jon flipped his Porsche, creating major brain damage for himself and that was the end of Dahlquist as a driving force. At least so I have heard from a number of different sources.

 

[Doodski]

I only know the names.
Fact: Jon Dahlquist was working with Saul Marantz Their collaboration resulted in a speaker that was being transported in their car and stolen when it was broken into. Supposedly a new design that would upend the speaker business in the same way the DQ 10 did.
Un proven to me (classified as rumor in my mind) Then, apparently, Jon flipped his Porsche, creating major brain damage for himself and that was the end of Dahlquist as a driving force. At least so I have heard from a number of different sources.

I am not familiarized with the tragedy you describe. The speakers of the time that I describe where both black velvet on front and where black to reflecting light and where cool and where bright sounding to most people but had a interesting brilliance about them for classical listeners.

 

[EJ3]

I am not familiarized with the tragedy you describe. The speakers of the time that I describe where both black velvet on front and where black to reflecting light and where cool and where bright sounding to most people but had a interesting brilliance about them for classical listeners.

Jon Dahlquist did have a connection with Magnat: (all M 90X series of the DQ line had this similar construction)
Dahlquist DQM-9 is a 3way, vented-enclosure system constructed in a conventional box format (unlike the well-known Dahlquist DQM-10). Since the woofer-compartment ports open to the rear of the cabinet, the speaker should not be placed closer than about 6 inches from the back wall, and the installation instructions also suggest floor placement on low stands. The DQM-9 uses 3 matched drivers made by the West German firm of Magnat, by whom Dahlquist is licensed. The drivers are vertically aligned, and all visible metal surfaces are finely finished. The 11inch woofer has an edge-wound ribbon voice coil and operates up to 450 Hz. The midrange employs a 5inch c1, also with an edge-wound ribbon voice coil. The tweeter, which takes over above 3,500 Hz, is a 1inch dome radiator. The enclosure of the DQM-9 is made of a special particle board (also apparently of German origin) whose several layers of wood particles increase in density toward the outer layers of the board. The side walls are formed of a combination of 3/4 and 5/8inch boards coated with a damping material on their inner surfaces. The entire exterior of the enclosure is covered with 3M "Nextel," a grey material resembling flocking that is said to damp surface resonances and lower the "Q" of the cabinet. The front baffle is covered with a black flocking material to control diffraction effects. The black, acoustically transparent grille cloth is held in place with magnetic fasteners at the corners of its wooden frame.

3M 'NEXTEL' is still available: Both lightweight and durable, Nextel ceramic fibers and textiles are designed to meet today's most demanding thermal, mechanical and electrical performance requirements. Made of continuous ceramic oxide fibers, Nextel products are available in a variety of forms, including chopped fibers, sewing threads, braided sleevings and woven fabrics.

 

[Doodski]

The enclosure of the DQM-9 is made of a special particle board (also apparently of German origin) whose several layers of wood particles increase in density toward the outer layers of the board.

Far out. I think of varying resonance frequencies applied to sort out the varying density/layering stuff.
Did you get to do the MB Quart home speaker stuff in the 80s and 90s?

 

[EJ3]

Far out. I think of varying resonance frequencies applied to sort out the varying density/layering stuff.
Did you get to do the MB Quart home speaker stuff in the 80s and 90s?

Knew some who did, I was busy with my lawncare business that I had started at 10, bought a rider at 11 & a dedicated edger (no more hatchet) at 12. By 14 I was able to buy my own new (with half of it paid for by my parents as both my Christmas present & 15th early birthday present Honda CL175. That ended my pool shooting carreer as I was a guy with his own transportation. That caused me to get lost into making money so I could be with girls.
I did not get into audio until I was 18 and Joined JR Achievement. We formed a company of which I was president to do a 1/2 hour radio show. I ended up with a Best Business Man of the year award.
Our mentor had Theadra, G.A.S. Ampzilla, crown, Frazier speakers, then later DQ-10's, Accustat-X's, all kinds of things (He was the head of news at a major to our area radio station, as well as doing things with the sate division of NPR. I got the audio disease from him somewhere between 1975 & 77. Before I knew it I had an ADVENT 300, a Connoisseur Turntable with a Grace tone arm & a pair of Frazier Super Monte Carlo speakers & I was off & running.
I was a DJ with a Honda SL 350, then a Honda 550, great audio gear, helping design sound systems for live band dance clubs, hanging out with Dr. Hook & the Medicine show, Bachman/Turner Overdrive, Johnny Winter, girls, girls. girls & all the craziness that comes with that lifestyle. I moved to the French Quarter of New Orleans, Kenner, Meterie, Louisiana, Lived in 1/3 of a mansion at 17th & P NW in DC, Falls Church, Virginia & Greenbelt, MD. But I always had some good audio gear. I left all that in 1984 to work at Porsche Cars North America as a translator & teacher of Quality control. Thank God I got out and stayed out. I finally got married in 2005, when I was 48. Before that, I was not fit to be a husband. Audio stuff, cars, motorcycles were pretty much my life until 2001.
Then I started traveling the Asian part of the world (I had done Europe 9 times for months at a time before I was in my 40's),
Met the woman that would become my wife on the island of Saipan & married her 2 years later.
During my earlier times: Build some audio gear, speakers or whatever? It crossed my mind momentarily and would be gone like a wisp of smoke. There were women too many women out there to be sitting at home building something.
By the way, I was mostly committed to who I was with for longer periods of time 10 years, 2 years, 4 years, something like that, (mostly serial monogamy). Then there were years of committed 3 some's wit 2 women. That becomes very money & time consuming and that life style causes a lack of commitment to marry.
Now, instead of having 11 cars, 2 motorcycles & no home, I've got a wife, 2 cars & 4 homes in different parts of the world that are paid for.
I'll retire Jan 1, 24 & perhaps look at some DIY stuff.
As it is, I am working like heck trying to get this 4th house set up to be livable (The back half was 1.5 inches lower than the middle & the front). There is a lot of work for me to do here.

 

[Vader540is]

Something strange I noticed... some online photos of the back of this amp, and also the service and user manuals show as you describe with the R+ and L- tied to ground. But others, including the photo of amp in this review, show R- grounded. Do you know if NAD made two versions of the 2200 with these differences? It doesn't look like this was part of the modifications that were done.

Did you ever find the answer? My NAD 2200 also has R - & L - grounded.