Apologies to damacman

[motorstereo]

Yes like it says I owe Tony an apology for not believing him in a thread that got closed (I'm sure I had something to do with that) that a Proton d1200 could best my beloved MC2500's. Dammit how can this be??? The bass is no doubt better than my bridged 2500's on my Polk 1.2tl's and had me thinking structural damage to the building. That lowly 1200 is no doubt the better amp than a single 2500 and it's a toss up for sheer volume with the bridged 2500's. Imaging and soundstage width and depth are a close call. I believe I'm going to have to leave the 1200 in for a while for some longer term listening impressions and give the Mac's a rest. Damacman you were correct and sorry I doubted you.

 

[biscuithead]

cool. I love AK

 

[c_dk]

Since in bridged mode the MC2500s do not have a common ground how did you have your Polks hooked up to them?

 

[4-2-7]

Yes like it says I owe Tony an apology for not believing him in a thread that got closed

And I wasn't in it, how did I miss the fun

 

[62caddy]

Proton D1200 was (and still is) a lot of amplifier for the money. It and the D940 receiver (which I still own) got high marks in the audio press in their day and rightly so. So I for one am well versed and appreciate the capabilities of Proton products of the '80s. That said, I would also add (and I'm sure Tony would agree) that in terms of build quality & longevity, a typical McIntosh amplifier is in a different league from a Proton D1200 which will not tolerate hard use the way a Mc can.

Lots of reports of D1200 fried boards because people treating it as though it were a 1,000 wpc RMS amplifier which it simply is not.

*Hadn't realized that previous thread got closed either...must be getting old.

 

[damacman]

I lost a steak dinner betting my MC2500 could best the D1200 driving the subs in my home theater.

Sometimes, it just is what it is ...

 

[c_dk]

We were a original US dealer for NAD back in the late 70s when I believe their units were made by a OEM supplier that then came out with their own product called Proton when NAD moved on to new suppliers with much better reliability.

The Proton stuff was not well made but I do believe that the company kept trying to recapture the success that NAD gave them.

The name Fullett sticks in my memory as the Tiawanese OEM??

Looks to be some sort of "H" class power supply amp according to the schematic though trying to figure out what the virtual dashed box transistors are gives me a headache......

 

[62caddy]

Foster?

 

[c_dk]

Could start a thread in general audio about all the companies that tried to catch "lightning in a bottle" like Carver did with the cube, NAD did with the 3020, Rotel did with the CD555 and Mac did with the 50w-2..... But most just don't have the follow up products that the mentioned companies did.

I will say though I seriously doubt that most, maybe 90% of the Mac owners I have known over the last 40 years would define good bass the same way as the posters here......but that was always part of the challenge, finding reliable, repeatable ways to deliver what the client wanted.

 

[motorstereo]

Since in bridged mode the MC2500s do not have a common ground how did you have your Polks hooked up to them?

I added a ground isolation transformer to the interconnect cable which allows the use of non common ground amps. This also has the added benefit of quieting the ground circuit as well with a single amp.

I lost a steak dinner betting my MC2500 could best the D1200 driving the subs in my home theater.

Sometimes, it just is what it is ...

I also would've taken that bet to and I would've lost. I was going to swap out my 2255 for the Proton as I thought that would've been a more fair match up as I didn't think the 1200 would have a chance against the bridged 2500's. Surprise surprise I can now say in my best Gomer Pyle voice lol. I can also say that damned 1200 will easily squash my strapped 2100's also

Proton D1200 was (and still is) a lot of amplifier for the money. It and the D940 receiver (which I still own) got high marks in the audio press in their day and rightly so. So I for one am well versed and appreciate the capabilities of Proton products of the '80s. That said, I would also add (and I'm sure Tony would agree) that in terms of build quality & longevity, a typical McIntosh amplifier is in a different league from a Proton D1200 which will not tolerate hard use the way a Mc can.

Yes that's my thinking as well and I've noticed the 1200 does get quite warm after lighting up the secondaries for a bit. Long term yes my money is on the Mac as well.

Could start a thread in general audio about all the companies that tried to catch "lightning in a bottle" like Carver did with the cube, NAD did with the 3020, Rotel did with the CD555 and Mac did with the 50w-2..... But most just don't have the follow up products that the mentioned companies did.

I will say though I seriously doubt that most, maybe 90% of the Mac owners I have known over the last 40 years would define good bass the same way as the posters here......but that was always part of the challenge, finding reliable, repeatable ways to deliver what the client wanted.

My idea of good bass on my rig is to have no need to turn on the 18'' corner load sub. With the 1200 running I have no need for a sub but with the Mac's occasionally I like a bit extra oomph to the music
.

 

[apachef1]

The difference between the Mcintosh Mc-2500 and Proton D1200 reflects in a few specification between the two amplifiers.

Mcintosh amplifiers typically have very low damping factor - this translates into loose woofer control for low frequency reproduction. A damping factor over 200 will have better woofer control and low end response compared a Mcintosh amplifier with a damping factor of 23. (Mcintosh did a study back in the day about damping factor and the effect on amplifier sound. Mcintosh engineer didn't seem to think there was any significant affect on the sound of the amplifier). After a damping factor of 250 there is very little if anything to be gained, so looking for an amplifier with a 1000 damping factor will mean very little compared with a 250 damping factor.

Second spec, the Proton D1200 has a dynamic headroom over 7db, giving the Proton very high peak reserve power output. At 500 watts/ch from the Mc2500, high dynamic headroom is really not necessary.

Overall the Mc2500 will last till the end of time and the Proton D1200 will blow itself up many times over again to keep up with the Mc2500. If bass is the issue, get a Bryston 4B or Adcom GFA555 and bi-amp to run the bottom end, both amplifiers have better damping factor vs a Mcintosh amplifier.

 

[whoaru99]

...
Mcintosh amplifiers typically have very low damping factor - this translates into loose woofer control for low frequency reproduction. A damping factor over 200 will have better woofer control and low end response compared a Mcintosh amplifier with a damping factor of 23. (Mcintosh did a study back in the day about damping factor and the effect on amplifier sound. Mcintosh engineer didn't seem to think there was any significant affect on the sound of the amplifier). After a damping factor of 250 there is very little if anything to be gained, so looking for an amplifier with a 1000 damping factor will mean very little compared with a 250 damping factor.

Second spec, the Proton D1200 has a dynamic headroom over 7db, giving the Proton very high peak reserve power output. At 500 watts/ch from the Mc2500, high dynamic headroom is really not necessary.

Overall the Mc2500 will last till the end of time and the Proton D1200 will blow itself up many times over again to keep up with the Mc2500. If bass is the issue, get a Bryston 4B or Adcom GFA555 and bi-amp to run the bottom end, both amplifiers have better damping factor vs a Mcintosh amplifier.

Myself, having amps with DF of 20 or less and greater than 1000 (and points between) agree with the McIntosh engineer. Generally, i find it a less than useful comparison between amps because pretty much always there is so much else different between the amps being compared to pin it on just one or two specs.

Power here, could be a material factor though.

The Proton information suggests it is capable of 2000 watt peaks, give or take, in bridged mode.

The MC2500 is 1000 watts bridged, but the dynamic headroom isn't given where I looked. Considering 1.5dB dynamic headroom isn't out of line for "normal" amps, that suggests peak output of around 1400W.

Some sort of measurements would be cool to try to pin down more accurately what's going on here. But, that would be lots of work for just a point of curiosity.

 

[c_dk]

I had two client's back in the day with bridged MC2500s......on the bench with a variac to ensure no AC voltage sag all four put out a bit above 1700 watts as PG lights lit up......yes my Mac load box got very warm. I think it was the only time the load box fans have kicked on in 35 years.....

 

[apachef1]

Myself, having amps with DF of 20 or less and greater than 1000 (and points between) agree with the McIntosh engineer. Generally, i find it a less than useful comparison between amps because pretty much always there is so much else different between the amps being compared to pin it on just one or two specs.

Power here, could be a material factor though.

The Proton information suggests it is capable of 2000 watt peaks, give or take, in bridged mode.

The MC2500 is 1000 watts bridged, but the dynamic headroom isn't given where I looked. Considering 1.5dB dynamic headroom isn't out of line for "normal" amps, that suggests peak output of around 1400W.

Some sort of measurements would be cool to try to pin down more accurately what's going on here. But, that would be lots of work for just a point of curiosity.

I can say the Mcintosh Engineers are correct in saying that DF has no real affect on amplifier sound. Its at the speaker end where the waters get muddy, literally. Loose woofer control contributes to cancelled bass wave formation in and outside the speaker box. I did a comparison years ago with a Mark Levinson 23.5 and Mcintosh MC2300. The Levinson was the clear winner in the bass dept, I could see tighter woofer control vs the Mc2300 and much tighter coherent bass and sound overall, the Mc-2300 had the classic MC tube sound you guys all know and love, myself included. The Levinson amplifier has a 600 DF and I think the Mc2300 comes in around 17.

I'm not saying the Levinson sounds better or worse vs the Mc2300, they both have their signature sound. The term sounds better is highly subjective and dependent on the speaker they drive.

 

[motorstereo]

After several hours of listening yesterday and looking for reasons to pull the Proton I did finally find one. It doesn't have blue meters I lit up the secondary lights several times but did not hit the 3rd as it was obscenely loud and I was worried about tweeter damage (there wasn't any thankfully). The 1200 did get quite warm (Polks are 6ohm) but not hot. Low level listening is also quite nice without a complaint anywhere.
I'll just have to think of it as a giant killer along the same lines as a 2 stroke Yamaha street bike I had in the early 70's. The end result is both 2500's are staying right where they are but I am very surprised by the little 100 wpc Proton.

 

[c_dk]

What is your AC voltage at? The east coast power grid has been known to sag as all the air conditioners get turned on in the big cities.......

Switching rail supplies, because of multiple transformer windings deal with voltage sags differently....the low voltage rails are expected to sag.....

 

[apachef1]

motorstereo,

The Proton D1200 had the "wow" factor in the heyday. The Mcintosh gear is so much more pleasurable to listen to in comparison. The Proton will sound fine at low to moderate listening levels but will not fill the room with clean defined sound when pushed hard like the big Macs. The Proton will end up in the dumpster long before your next Mcintosh major service.

 

[whoaru99]

I can say the Mcintosh Engineers are correct in saying that DF has no real affect on amplifier sound. Its at the speaker end where the waters get muddy, literally. Loose woofer control contributes to cancelled bass wave formation in and outside the speaker box. I did a comparison years ago with a Mark Levinson 23.5 and Mcintosh MC2300. The Levinson was the clear winner in the bass dept, I could see tighter woofer control vs the Mc2300 and much tighter coherent bass and sound overall, the Mc-2300 had the classic MC tube sound you guys all know and love, myself included. The Levinson amplifier has a 600 DF and I think the Mc2300 comes in around 17.

I'm not saying the Levinson sounds better or worse vs the Mc2300, they both have their signature sound. The term sounds better is highly subjective and dependent on the speaker they drive.

Levinson No. 23 is one of the amps I have in the span of 20 or less to 1000 or more.

 

[apachef1]

Its a great amplifier did everything well and seemed like no end to the volume control. Sorry I sold it.

 

[motorstereo]

What is your AC voltage at? The east coast power grid has been known to sag as all the air conditioners get turned on in the big cities.......

Switching rail supplies, because of multiple transformer windings deal with voltage sags differently....the low voltage rails are expected to sag.....

It's a fairly consistent 120volts according to my Belkin PC. Both Mac's are plugged directly into wall and on different dedicated circuits so there's no sag.

motorstereo,

The Proton D1200 had the "wow" factor in the heyday. The Mcintosh gear is so much more pleasurable to listen to in comparison. The Proton will sound fine at low to moderate listening levels but will not fill the room with clean defined sound when pushed hard like the big Macs. The Proton will end up in the dumpster long before your next Mcintosh major service.

Yes I agree and that's what I'm thinking as well that the Mac's will still be around long after the Proton is a distant memory. The problem is the 1200 filled the room with great non fatiguing sound to. If or when the Mac's do need servicing the 1200 will make a much better fill in than my Onkyo 508 did when I had one 2500 recapped several years ago.