Proton D1200 / AA-1150 / AA-2120 Owners Thread

[karljansen]

It has been decided by a handful of Proton D1200 owners that we need an owners thread at AK, and I have been nominated for the task. I'm including the AA-1150 and AA-2120 since they look almost identical and they might as well be included. I would like to learn more about the AA-2120, as it is supposedly a true dual-mono amplifier without the Dynamic Power on Demand (DPD) feature found on the 1200 and 1150.

I purchased a nce specimen (as seen in above photo) on ebay a couple of years ago, and promptly had my audio tech do some upgrades, such as the more robust RCA terminals that screw on to the chassis, LED lighting, and some new transistors. Well actually, there may have been an issue related to shipping such a heavy unit to me, because after a couple of weeks of ownership I switched on the unit and 4 or 5 transistors blew with a puff of smoke! My tech thinks there may have been a tiny, stray piece of metal that shorted something out but we'll never know.

My speakers and listening room do not even come close to being able to fully utilize the power output capabilities of this amplifier. I'm including some photos of my amp in a couple of configs, such as paired with an old NAD Monitor Series 1600 Preamp, a top view showing how densely packed the internals are, and then some additional photos found on the web showing the large capacitors, and a Proton product brochure from the period.

This thread is a place to talk about upgrades, sound, specs, tests, equipment you've paired with the amp, repairs/restorations, and any helpful tips.

 

[jupitersspot]

The shipping incident that shattered my D1200's front glass panel also mangled the speaker binding posts on the back panel, destroying the plastic plate in which the speaker posts are mounted. If anyone has found a nice replacement, give a shout and a link. My approach is likely to be fabricating a metal sheet to plug the hole where the plastic was, and then drill and install some generic 5-way binding posts.

 

[red 111]

I’ll join I’ve got the Proton 740 cassette deck & the proton 300 radio with the 301 stereo speaker…

 

[karljansen]

I’ll join I’ve got the Proton 740 cassette deck & the proton 300 radio with the 301 stereo speaker…View attachment 2832749

That radio was the very first Proton piece of gear I ever noticed, and apparently it left an impression because I still remember exactly where and when. I was in high school, and this very rich kid decided to throw a party while his parents were away. I noticed that radio on his kitchen counter while getting myself another drink. It was a really beautiful and expensive house so that probably affected my perception of seeing the Proton in it.

 

[red 111]

That radio was the very first Proton piece of gear I ever noticed, and apparently it left an impression because I still remember exactly where and when. I was in high school, and this very rich kid decided to throw a party while his parents were away. I noticed that radio on his kitchen counter while getting myself another drink. It was a really beautiful and expensive house so that probably affected my perception of seeing the Proton in it.

Yes… back in the day the combo was about $600 … I caught a super sale & bought the radio for $150 & about a month later Lyric HIFI sold me the 301 speaker for $100 demo…inputs on back you can connect Cd player via aux

 

[sregor]

Not an owner, but would if one crossed my path. One variant of the D1200 was made for AR - the P-10 amplifier. Same boards and parts, but slightly higher low voltage and rated at 120 watts per channel, (but no meters. )
Picture from net
There is a thread about it somewhere around here, and the board said 1200 on it, and the caps said Proton.

 

[karljansen]

Not an owner, but would if one crossed my path. One variant of the D1200 was made for AR - the P-10 amplifiwer. Same boards and parts, but slightly higher low voltage and rated at 120 watts per channel, (but no meters. )
Picture from net
There is a thread about it somewhere around here, and the board said 1200 on it, and the caps said Proton.

There's another variant that looks identical to the D1200 including the meters, but under a different brand name. I have a photo of it in some folder somewhere but can't find it. I could've sworn the brand was "Onyx," but I can't seem to find anything about it searching google. Will post it if/when I find it.

 

[karljansen]

Found it! It's the Onix A2150. I'm guessing it's a rebranded AA-2120. There's one for sale on ebay right now: https://www.ebay.com/itm/225469032321


More with the internals. If this is accurate, then it's very different from the D1200. Wonder if that's what the AA-2120 looks like:

 

[karljansen]

A couple more variations. Apparently there was a gold face AA-2120 with matching preamp. Probably very, very rare, and hard to find any info about it. Last pic is a D1200 with wood sides, probably custom made by someone:

 

[stereo98]

Recently a very proud owner of an AA-1150, and all I have to say is this baby isn't going anywhere, there are some chips on the glass panel but the the monstrous bass extension this thing puts out makes me forget all about that. The meters are just the cherry on top. I'm a believer.

 

[Boba MosFET]

I have the D1200. There is no substitute...

I just need one of their preamps to complete it. Should I get the AP1000 or the P1100?

 

[karljansen]

I have the D1200. There is no substitute...

I just need one of their preamps to complete it. Should I get the AP1000 or the P1100?

I have no firsthand experience with the preamps, but here are some photos of a D1200 and AP1000 that are currently for sale on a German site called Werner Musica. For the right price I would definitely like to have one to go with my D1200.

 

[motorstereo]

My Proton d1200 with new led bulbs. Now the speaker connectors need to be fixed. I've owned it for close to 20 years now and it seems to be something constantly acting up. Ribbon has been fixed, rca's upgraded over the flimsy way Proton designed it, internals have been gone through with one output transistor found to be not soldered in from the factory. Despite it's unreliability issues it's the only non Mcintosh amp that I currently own and I'm looking forward to the day it's back up and running once again.

 

[Boba MosFET]

My Proton d1200 with new led bulbs. Now the speaker connectors need to be fixed. I've owned it for close to 20 years now and it seems to be something constantly acting up. Ribbon has been fixed, rca's upgraded over the flimsy way Proton designed it, internals have been gone through with one output transistor found to be not soldered in from the factory. Despite it's unreliability issues it's the only non Mcintosh amp that I currently own and I'm looking forward to the day it's back up and running once again.

Proton QC was not the best in the 80s. Most of the issues were bad solder joints and the occasional garbage capacitor. When their stuff worked there wasn't very many things that could compete with them for performance or appearance, IMO. Mostly slightly altered NAD designs but with better parts.
What parts did you use to replace the RCAs, and how did you attach them to the back panel?

 

[Boba MosFET]

I have no firsthand experience with the preamps, but here are some photos of a D1200 and AP1000 that are currently for sale on a German site called Werner Musica. For the right price I would definitely like to have one to go with my D1200.

Nice pics! Proton lifted the muted NAD style but added nice touches like the Alpine green power buttons, or the full face glass panel instead of just two meters sticking out of brushed metal like a lot of other amps before them.

Based on the specs posted on HifiEngine it looks like the 1100 should be the better preamp. Lower THD, better S/N in the line stage as well as both phono cartridge loads. Despite this, all the recommendations I've seen have put the 1000 over the 1100.

 

[motorstereo]

What parts did you use to replace the RCAs, and how did you attach them to the back panel?

Not sure what parts were used as this was done 20 years ago. He secured them to the chassis rather than the circuit board like Proton did. I have no idea why Proton would do such a thing as those rca's were always loose and losing contact. The fellow that fixed it said it was common issue and he'd done the same repair many times. The 1200 has been a problem child since day one and I keep hoping each fix will be the final one. Now if I could get the speaker connecters to connect and not drop out like the rca's used to I could listen to it once again.

 

[karljansen]

Proton QC was not the best in the 80s. Most of the issues were bad solder joints and the occasional garbage capacitor. When their stuff worked there wasn't very many things that could compete with them for performance or appearance, IMO. Mostly slightly altered NAD designs but with better parts.
What parts did you use to replace the RCAs, and how did you attach them to the back panel?

Don't ask me how to do the job because I had a friend do it.

The exact part I ordered no longer appears on the site, but this part is similar:
https://www.soniccraft.com/product_info.php/cardas-ctfa-rca-p-1452?osCsid=87pea6tbchru8es97svfvrlm27

This should work and is cheaper:
https://www.parts-express.com/Chass...y0ymDrS2d99IdipIfwzQ-30TqqaF9jD-3HVSshtqVeK_0

They really cut costs on the speaker terminal assembly as well. Mine were bashed in and lying on top of the board inside when I received mine. At least the glass was fine.

 

[Boba MosFET]

Those original speaker terminals are terrible. Besides being fragile they are also incompatible with most spades. My Carver M4.0t is the same way. It's either bare wire, which I don't like, or banana pins, and I don't have enough cables with those ends here. They're easy enough to replace though.

I have extras of those and of the RCA connectors here, so when my new lamps come in I'll do all three at once. And look for the preamp.

 

[Boba MosFET]

Yes… back in the day the combo was about $600 … I caught a super sale & bought the radio for $150 & about a month later Lyric HIFI sold me the 301 speaker for $100 demo…inputs on back you can connect Cd player via aux

Those radios were very highly rated back then, and they're highly sought after today. I wonder about putting a Wifi DAC/streamer gizmo on a Proton 300/301 pair and see how well they'd hold up against something like the Sonos Play 1.

 

[karljansen]

The prices people try to get on Reverb can be utterly delusional. Here's a D1200 with asking price of $1149 shipped. The justification is that they recently sold an AA-1150 for $749 so they thought they'd tack on an additional $400 for the D1200. The ad also says they have two more D1200's that they're keeping, so we also have a D1200 hoarder!

Two years ago I bought my D1200 for around $650, not including shipping, and I thought that was a little too high at the time - they were going for around $450-$500 if you were lucky on ebay, but I could see that prices were starting to inflate, which is why I went for it. $1149 might be justifiable if the unit was fully recapped, and it should also be noted that the 4 giant caps are impossible to find in a size that will fit the chassis, so you better hope those don't die.

The ad also incorrectly states that the D1200 is "dual mono." It's my understanding that that's not true and that one section is for normal power and the other is for the dynamic power.

I'm a musician who is always looking for recording gear and Reverb is the greediest, most price-inflated marketplace out there. People seriously need to chill and check ebay's "completed/sold" search function to see what people have actually paid for something. To my knowledge no one has ever paid $1149 for a D1200. What do you guys think about this?