PROTON Audio, NAD and Dynaco are Cousins. Inventor of Dynamic Power on Demand Amplifiers.

July 11, 2018

#257

Updated August 29, 2021

Foreign language brochure, shows AA-1200 power amp.

Gentle reader,

This article has become my most popular. I thank you, dear reader for that. I just found on eBay, an AA-1660 six channel power amplifier. Photos are below.

As you know, I have been into good stereo equipment on a budget since 1976 when, at 19, I built a Dynaco PAT-5 preamplifier and a pair of SWTPC Tiger .01 60 watt mono power amplifiers. For speakers, a pair of floor-model Dynaco A-25s. Turntable was a B.I.C 940 with walnut base, smoke dust cover and whatever cartridge came with it.

Since I came across blogger.com, and tried my hand at this blogging thing, to my surprise people like what I write about. A lot of people. So thank you for taking the time to read my humble words and view my photos.

NOTE: Almost all of the photos in this article were culled from Internet searches and from eBay active auctions. IF you made any of these photos, please let me know so that I can credit you. 

ALSO NOTE: If reading on a PC, if one clicks on any photo, a window opens in front of this page and one can click or use their arrow keys to see the photos larger.

This is a long article, but if you are interested in PROTON or have never heard of it, bear with me as I open your eyes to this unique company that made some truly remarkable components, many of which are highly sought after to this day.

 

Those of us in the home audio community are no doubt familiar with NAD components. I had a receiver they built. NAD is an abbreviation for New Acoustic Dimension.  NAD components were built in Taiwan, a Chinese country on a large island south of China. Mainland China is not happy that Taiwan continues to refuse to rejoin the mainland country. But this article is about stereo equipment and not geopolitics.

Above shows a NAD receiver I once owned.  

This is the back of it. Keep this image in mind when viewing later photographs of PROTON equipment. Below is a NAD receiver, which I did not own, but am including for reference. Compare it's rear view to the PROTON D540 shown further below.

NAD is well respected as is Dynaco which is a much older company and originally American. PROTON came about in the early 1980's and were built in the same factory as NAD equipment, but of course they were completely different circuits and products.

My 2002 Orion Blue Book on Audio lists 77 separate PROTON items. They also list a great number (33, I just counted) Dynaco by PANOR components which were later also made in the same factory. I wrote about that here:

Dynaco Given a Second Life. Pan Orient Company: Panor for Short. A Photographic History PART ONE. 

Yet, my research for the three-part article on PANOR, the company that produced the 1990's Dynaco equipment, also from the same factory, revealed far less devices that actually made it to the public. Those articles and all the rest of my articles on Stereo equipment can be found here:

EVERY Blog Article I Have Ever Written and Illustrated About Stereo Equipment and Speakers Galore!

So where am I going with all of this? Glad you asked. I discovered PROTON equipment quite by accident, or should I say, in the usual way: on eBay. I was looking for a preamplifier and came across a PROTON D540 integrated amplifier which, like the NAD receiver above, could be electrically separated into a preamplifier, power amplifier or perhaps both at once.

If you are noticing a trend here of photos showing more of the top than the front of these components, you are correct. The hardest thing to photograph are black or shiny, due to reflection of the flash causing glare on part of the face and darker to the sides.

Note the similarities with this rear view and that of the NAD? Same: ground screw, gold phono terminals, white stripes between RCA terminals, same "U" jumpers between preamp and power amp section.

Dynamic Power on Demand, as mentioned above, is a PROTON invention.  A contemporary review from Stereo Review magazine by Julian Hirsch which completely explains the way it works. In the article he said, "The Proton D540 is not only the most powerful '40-watt' amplifier we have used, it is one of the few of any rating whose capabilities begin to encompass the dynamic properties of live music." I wrote about that here:

Details on the remarkable PROTON D540 Integrated amp's huge 530 watt power output. 

PROTON went on and built on their fantastic circuits putting them in separate Power Amplifiers as well. Starting with the AA-1150 in 1987. 50 watts-per-channel with the DPD circuitry produced instantaneous clean power upwards of 500+ watts to handle crescendos with aplomb.

Isn't it lovely? Everyone loves VU or watt meters and these babies look so good with green back-lit markings. Sadly, I have not been able to afford any PROTON power amplifier. But have had two D540 units and can testify to the accuracy of the claims (and test results) of the DPD circuits. It works as advertised and no discernible distortion could I hear.

According to Orion, they made a total of seven power amplifiers including one 4-channel, one 5-channel and one 6-channel model. Those that appear in searches, and I've only seen stereo ones, go for big prices. Their DPD legend precedes them.

To further touch on the DPD circuits, let's look inside a D540 amplifier. Note the two transformers above, on the right, and two sets of capacitors? One is for class A up to 40 wpc. The second set is for DPD 41 watts and higher to an astounding 530 watts!
Below, shows the two sets of transistors mounted beneath the curved heat sink. Small pairs are for Class A use, larger pairs are for DPD use. 

Now, I'm going to show you photos of every PROTON component that I have owned and/or found in my research for this article. There are a number of them.

 AD-630 cassette deck. Ever seen anything like this?

A trio of components: AT-470 tuner, AC-420 CD player and AM-455 integrated amp.

AT-300 tuner atop AM-300 integrated amp. Look how similar their faces are. Not a knob to be seen.

Unlike the D540, these two integrated amps lack the DPD circuits invention. They are not separated into preamp/power amp sections either. Note, they DO have three-way binding/banana speaker terminals which the D540 lacks.

Above, AD-200 cassette, cheapest model. Seller still had the original box and claimed it was brand new.

 Most commonly found on eBay, the AD-300 cassette.

 AD-720 cassette above. Odd looking, isn't it?

 AD-720B cassette, above.

 AD-740 cassette, above. I believe it is top-of-the-line.

This, the AC-300II CD player was mine, the black anodizing has faded over time.

 AC-420 CD player, above.

AC- 620 CD player, above.

Blurry, AM-300 integrated amp, (above) has DPD. Below is the rear which has the desirable (at least to me) three-way binding/banana speaker terminals.

 (No prefix) 520 Integrated amp, above and two below.

  520 does not have DPD and has cheap spring terminals.

 540 integrated amp below. No DPD.

 Two rear views of the 550. Seller had RCA cables instead of "U" plugs. Note, again, cheap spring speaker terminals.

AM-452 Integrated amp, above and below, very basic.

 AM-656 integrated amp, above and below.

AM-656 has DPD and 3-way speaker terminals. Note differences below compared to the D540 integrated amp's layout. Similar to AA-1200 power amp's layout.

Next, more photos of Power Amplifiers. Remember, so far, I have only been able to find photos of STEREO amplifiers. 

Starting with more pictures of an AA-1150. Top shows tell-tale sticker on the left proclaiming it has DPD.

Interior of AA-1150 is simpler than the AA-1200. Still, two toroidal transformers, one to supply the Class A to 50 watts the second to go up from there when DPD kicks in.

Externally, the AA-1200 is almost identical to the AA-1150. Yet, the 1200 is Class A all the way to 100 watts per channel.

Here is another look at the cover of the brochure at the top of the article to show the AA-1200 interior. I cropped it for more detail.

Below, are photos of a rare SIX channel PROTON AA-1660 power amplifier which, as of August 29, 2021 is for sale on eBay. These are these are the sellers photos.

Now, for the photos of the TWO Preamplifiers I could find. One, the 1100 was mine. The other one, is the AP-2000.

They listed it as untested. I assume it was made for home theater use with a heretofore unseen six channel preamplifier/tuner.

The 1100 preamplifier came out in 1985 and is very complete and well laid out. The important Infrasonic filter is there as is the ability to record one source while listening to another. Plenty of inputs including two tape/CD-R loops and two pairs of outputs. Note the two white stripes like the NAD units and the same phono ground screw.

Note variable capacitance for phono cartridges.

I used every set of input terminals, too. I do not know what the high output terminals are for as an owner's manual is rare as hen's teeth. The are shown in larger detail, below.

 The three AC terminals came in handy.

The AP-2000 came out in 1993. It is similar, but different than the 1100. Some controls do the same job. The rear is similar but lacking switchable phono circuits and they have a third set of outputs, the third, due to the small size of this picture is unreadable.

Now, for stereo receivers for which there is not many photos available. SOME incorporated the DPD circuitry, but most did not. 

Whomever photographed this 930 receiver took lots of carefully composed photos. These are a few of them.

Only three inputs (plus tuner). Note it can be "separated" by removing the "U" jumpers.

Clean, uncluttered design, typical of PROTON.

Cheap spring terminals for speaker wire is a bummer. And look at how crowded it is inside. Single transformer denotes lack of DPD circuitry.

Next is the AV-300 receiver, I thought that prefix stands for Audio-Video, but it is a simple, yet DPD equipped stereo receiver.

Central window for LED display, of those I've seen for sale, all are faint and mostly unreadable. Note the total LACK of knobs and rotary controls.

 Proper three-way speaker terminals.

DPD sticker tells all that this is no ordinary receiver.

 Note phono inputs for both MM and MC cartridges.

The D940 receiver is also DPD equipped. Sadly, it has the same speaker terminals as the D540 integrated amplifier, they LOOK like they accept banana plugs, but they do not. Only bare wires can be used. BOTH came out the same year and have identical specs. The D940 of course includes an AM/FM tuner which makes it a receiver.

Orion Blue Book lists eleven receivers, yet I could only find photos of these two.  
Next, we look at a few tuners, including one that tuned in TV audio. I suspect to add to a system to incorporate stereo broadcasts.

Tuner 420 is purely analog with few controls. The rear is equally spartan.

 Tuner 440 is digital and mimics other PROTON products.

Above and below is the 600 TV tuner, a departure from the AM/FM variety to say the least.

PROTON did make televisions as well, so it is understandable they might make this too. They also produced clock-radios, a table radio with optional second speaker, under cabinet radio/CD players for the kitchen and other electronics.

I was intrigued by their all-in-one receivers, which unlike competitors, are full-size-17-inch-wide units and are VERY heavy! I've had three and the best was the last, the AI-3000 II model. They have a stereo tuner, amplifier, auto-reverse cassette deck and CD player. So, perhaps AI stood for All Included. Plus, they included a pair of quality speakers.

They were EXPENSIVE with the first model (in 1988) retailing for $1,300.00! The Series II was less at only $1,000.00, it came out in 1991. The AI-3200 came out in 1992 and was more compact and a relative bargain at $800.00.

This is the first model and one that I purchased. Almost all of them have lost the door that covers the controls at the bottom. This door also has the name and model number on it.

The first model is identified by the simpler rear panel with most of the devices to right of center.

They DO have three-way speaker terminals.

Below is the AI-3000II model. It is complete and everything works! See the normally missing door is there and still works.

Note the added on box (below) on the left? That is to fit the larger transformer. The CD player is of better quality as well. It came complete: AM antenna, remote control, owner's manual, everything except the speakers.

I believe that these are the speakers that came with the AI systems. A seller had them brand new, still in the box!

 Sadly, they need to be re-foamed.

I came across the following photos just recently which spurred me to write this article.

Here 'tis the ultra-rare AI-3200 all-in-one receiver. They made it smaller with a smaller cassette transport and other shrinkable items. And left out some things the others have.

Two inputs, neither for phono nor a pre-out pair of RCA terminals which could be used with a subwoofer.

Lastly, the rest of the catalog! I bought it from someone in Hungary, but the address is in the Netherlands and it seems to be German, but not. So, can anyone tell me what language it's in?

I was told today (June 26, 2021) this: "By the way the pricelist from Proton above is in Dutch, prices are in Florins (1 EUR = app. Fl.2,20)" You can use a Currency Conversion web site to convert to your money.

I chose full-sized for these images, but we cannot see them as such. I have no "device" to view my blog on, but on a PC, if one clicks on any photo, a window opens in front of this page and one can click or use their arrow keys to see the photos larger.

Below is page two. It tells about PROTON and some of the unique aspects of them. "PROTON - FOR THE MUSIC".

First components shown are preamplifiers atop power amplifiers. AP 100 preamp, D 1200 power unit. Then P 1100 preamp and AA 1150 power amp.

Page three shows the D540 integrated amplifier with DPD. Then the AM 300 integrated amplifier, followed by the AM 200 integrated amplifier. At the bottom is the DPD equipped P940 receiver. Finally at the bottom is the AV 300 receiver.

Page four shows three tuners and three cassette decks. Tuners are: P 440, AT 300 and AT 200. Cassette decks are P 740, AD 300 and AD 200.

Lastly, is a price list with "f" instead of the Dollar or Pound symbol. Again, I have no idea what language it's in.

That's it! That is all I have on PROTON components. Please feel to look at other articles I have written by clicking this link:
EVERY Blog Article I Have Ever Written and Illustrated About Stereo Equipment and Speakers Galore!  

Thanks for looking!

Scott

Updated August 29, 2021

#257