Audio Research D-100 power amplifier

[JBT]

We cannot recall when any new products have generated as much of a stir among perfectionists as the new solid-state equipment from Audio Research. Preceded by rumors of "a new kind of amplifying device—a cross between a tube and a transistor"—the announcement of ARC's new power amp and SP-4 preamplifier elicited very mixed reactions from loyal ARC customers, some of whom gleefully anticipated a virtual revolution in audio electronics, others of whom felt betrayed by the company which, having originally convinced them that "Tubes Are Better," suddenly seemed to be doing an about-face and espousing the views of the Enemy—the "Soiled-State"—forces.


Audio Research D-100 power amplifier | Stereophile.com

[Bill Stevenson]

Boy does this bring back memories. The Stereophile review in particular. I was selling ARC products in San Diego at the time these were introduced and was smitten with them. I bought two of them to bi-amp my Bozak Concert Grands. I also bought an SP-4A and a EC2 crossover network at the same time. That system was good enough to make goosebumps. But a customer/friend had Fulton J speakers and they definitely worked better with his SP3 and D76a combination. J. Gordon Holt was right about that. On Magnaplanar Timpani IV speakers, I liked two D100s switched to mono mode with an SP3. The D100 was a controversial amp from beginning to end. Bill Johnson lost me by coming out with a mod making the D100A less than a year after introduction, and then another mod to D100B not long after that. This act of vacillation left a lot of customers feeling like they were being used for R&D, at great expense to themselves. The worst part for me was that the original D100 was better by a margin than the D100A. I never got to the B version, selling my amps instead.

[tdelahanty]

Originally Posted by Bill Stevenson

Boy does this bring back memories. The Stereophile review in particular. I was selling ARC products in San Diego at the time these were introduced and was smitten with them. I bought two of them to bi-amp my Bozak Concert Grands. I also bought an SP-4A and a EC2 crossover network at the same time. That system was good enough to make goosebumps. But a customer/friend had Fulton J speakers and they definitely worked better with his SP3 and D76a combination. J. Gordon Holt was right about that. On Magnaplanar Timpani IV speakers, I liked two D100s switched to mono mode with an SP3. The D100 was a controversial amp from beginning to end. Bill Johnson lost me by coming out with a mod making the D100A less than a year after introduction, and then another mod to D100B not long after that. This act of vacillation left a lot of customers feeling like they were being used for R&D, at great expense to themselves. The worst part for me was that the original D100 was better by a margin than the D100A. I never got to the B version, selling my amps instead.

I had this conversation with Bill Johnson at the Chicago CES in the late 70's. The D100-A simply added more capacitors to the power supply. BJ was not happy when I told him he was milking his customers and the mod should have been in the original design.

I had a SP5 (SP4 without tone controls) and D100-A's, EC83 Xover and Timpani 1D's. Later I sold the amps and speakers and got IMF TLS80's and the D52-B which was much better sounding than the D100-A. The 52-B was 50w rms and very high bias (AB1), it was more spacious, detailed and open.

AR has a history of quietly building SS equipment for those of us that shun tubes and their (AR's) reliability issues in the mid 70's to early 80's.

[daveyf]

Originally Posted by Bill Stevenson

Boy does this bring back memories. The Stereophile review in particular. I was selling ARC products in San Diego at the time these were introduced and was smitten with them. I bought two of them to bi-amp my Bozak Concert Grands. I also bought an SP-4A and a EC2 crossover network at the same time. That system was good enough to make goosebumps. But a customer/friend had Fulton J speakers and they definitely worked better with his SP3 and D76a combination. J. Gordon Holt was right about that. On Magnaplanar Timpani IV speakers, I liked two D100s switched to mono mode with an SP3. The D100 was a controversial amp from beginning to end. Bill Johnson lost me by coming out with a mod making the D100A less than a year after introduction, and then another mod to D100B not long after that. This act of vacillation left a lot of customers feeling like they were being used for R&D, at great expense to themselves. The worst part for me was that the original D100 was better by a margin than the D100A. I never got to the B version, selling my amps instead.

Wow, Bill!!! That brings back memories...I think you were the guy who sold me my first pair of Maggie's...were you working at Audio Dimensions ( Directions??) in the late 70's- early 80's??
BTW, I now own an ARC D70Mk2 and I think VERY highly of it. This amp has shown off many a newer design in head to head testing.

[CGabriel]

Does anyone now know what was so secret about the circuitry that it had to be potted?

[tdelahanty]

Originally Posted by CGabriel

Does anyone now know what was so secret about the circuitry that it had to be potted?

Yes, I can speak about the original circuit modules from the 70's/80's. Nothing unusual about the circuit design, it was the construction. The modules were made with a method the military called cordwood construction, which was meant to save space and be rugged. Normal components (resistors,caps & transistors) were stood-up, top to bottom, wire welded (in lieu of a pwb) and potted in a sealed enclosure; or had very thin pwb's on the top and bottom. I worked with these modules in various systems.

AR's literature of the period proclaimed the virtues of tube and solid-state, the sound of these components (amps & pre-amps) was typical of the period; slightly dark, soft and slow.

[Bill Stevenson]

Originally Posted by daveyf

Wow, Bill!!! That brings back memories...I think you were the guy who sold me my first pair of Maggie's...were you working at Audio Dimensions ( Directions??) in the late 70's- early 80's??
BTW, I now own an ARC D70Mk2 and I think VERY highly of it. This amp has shown off many a newer design in head to head testing.

It is very possible. I left the good doctor's employ to go to Breier Sound Center in I think 1977, which is still in business. Although I liked the sound of the ARC stuff better than McIntosh, I was torn because of the trade off caused by the reliability issues and the cost for upgrades and mods imposed by ARC back then. McIntosh stuff worked and none of my customers got hurt buying it. The Maggies on the other hand were great in every way. I still like them. With that said, ARC still has a sound that, at their best, I think is tough to beat. Currently I am using cj amp, phono stage, and preamp that all works and sounds good too. So much great electronics, so little time.

[daveyf]

Originally Posted by Bill Stevenson

It is very possible. I left the good doctor's employ to go to Breier Sound Center in I think 1977, which is still in business. Although I liked the sound of the ARC stuff better than McIntosh, I was torn because of the trade off caused by the reliability issues and the cost for upgrades and mods imposed by ARC back then. McIntosh stuff worked and none of my customers got hurt buying it. The Maggies on the other hand were great in every way. I still like them. With that said, ARC still has a sound that, at their best, I think is tough to beat. Currently I am using cj amp, phono stage, and preamp that all works and sounds good too. So much great electronics, so little time.

I'm fairly certain it was you who introduced me to Maggie's ( they were the model mg1 improved---I think??) . At the time, these were my first high end speakers. I had a HK A 500 integrated that the shop tech transformed into a preamp ( took a tap off the preamp section) and I ran that into a Hafler 220 that I had bought from Steve at Stereo Design. Wasn't too bad sounding. I sold the Maggies and bought Acoustat model 3's from Gene Rubin....I thought these should kill the Maggie's, BUT I was wrong. The model 3's were good, but they did't have the magic of those old Maggie's.

[Bill Stevenson]

The best news is that here we are all these years later engaged in audio. I hope it was me who sold you the Maggies and if so, I am proud to have done so. In the right room they are still great speakers. What do you listen to today? And are you Dave or Davey?

Bill

[daveyf]

I'm actually Dave...

Today my system consists of a Linn Lp12 with Radikal D, A WTA custom black arm with a Benz Ruby 2 feeding into a CAT SL1 Sig with Mullards , that runs into a Rowland model 8 with choke. The Speakers are Sonus Faber Guarneri Homage's/REL T5...all lashed up with Nordost Tyr. I also use an ARC D70mk2 as a tube alternative. The system makes music and works well in my small dedicated room. Here's a link to my system: AudiogoN Forums: Sonus Faber Guarneri system
I do agree that it is great that we are all still enjoying music with our systems all these years later. Thank you Bill!!