Just some thoughts on Mcintosh MC601 vs Theta Prometheus Class D amps

[Kevin M.]

I've listen to Theta Digital amps based upon Hypex class D amps. I was very biased against class D but came away convinced they are clearly high-end, top tier amplifiers . Some thing they do better than any solid state amplifiers I have heard around their price point. In other ways, I don't quite like them.
The sound stage was wide and deep. The amplifiers do true justice to all instruments, even those with delicate sounds that while one is aware they are present are seldom delinated to the point the would be in a live music presentation.At the end, though, there's still an "artifical" sonic signature that I don't quite hear in class A or AB amps. Theta's amps sound like what I hear with live amplified music.

The Mcintosh MC601 does most of what the Prometheus does but can't quite manage the amount of micro-detail of less "powerful instruments." No other amps I've audtioned around the price piont can match the Prometheus in this regard.The Mcintosh amps still remind me more of unamplified music. Sure all amps have a sonic signature but the newest line of Mcintosh amps really do a stellar job of allowing one to forget that you are listening to recorded music. The MC601 backgrounds are so dead silent. You get the impression that the singer is present in the room when you close your eyes with great recordings. With the last line, of amps, bass lines are tight and realistic without sounding artifical. Mcintosh is walking a perfect tight rope here.

With the Theta Prometheus, I never once forgot I was listening to recorded music, superbly sounding recorded music but still recorded music.The Theta amps are still really incredible amps as are the Mcintosh MC601s.

Class D is making the biggest inroad ever into the high-end. Over the years, many have asked if Mcintosh will travel the same road. I'm curious to see what happens as the technology evolves.. I haven't seen many comparisons between the two brands felt I should make some comments. My comments are just general impressions and I'd welcome any comments. I don't think one would "lose" with either of these amps.

 

[jdwk]

Interesting. I currently own Goldenear Triton one speakers and the woofers are controled by a 1600watt class D amp in the speakers, they sound pretty good I am running the speakers on a MC 2500 amp thats a hold over from when I had kappa nines. I am even wondering should I downsize the amp because the speakers arent really using the power.

 

[Mamrak1]

Class D has made large strides in sound quality. However, there is still an etched signature I can hear on higher frequencies. Maybe it doesn't bother some people. One thing that bothers me still, class D modules were supposed to lower the costs on building amplifiers. I see some pretty pricey Class D amps floating around the marketplace.

 

[damacman]

Interesting. I worked for Rockford Fosgate when class D was all the rage in car audio amplification. The promises were great - small size, less heat, less manufacturing cost, lower price to the consumer. All good things in car audio. [Prior to the introduction of the bd1000a1, the Power 1100a2 was nearly twice as much money.] When Class D first came on the scene in car audio, the efficiency approached 75%. As I left Rockford, efficiencies were approaching 85% and full range Class D was in vogue. We did lots of listening tests between full range Class D and Class AB amplifiers and at the time (as late as 2008), Class D just couldn't compete in the SQ arena. Now, nearly a decade has passed and the technology continues to mature.

When it comes to home audio, I've always looked at it like this - what is so compelling about the promise of Class D that would make one abandon their Class AB amplifier in favor of it? Weight isn't really a factor - you set it on a shelf and forget it. Efficiency isn't really a factor - most sane audio folk have one amplifier or a pair of mono blocks (and not 1,000 wpc either). Heat isn't really a factor - Class AB amplifiers really aren't reputed as running awfully hot . . . say like a full Class A design. OK, sure - it's nice to be able to use Class D amplification for powered subwoofers for all of the same reasons that are attractive in car applications. That leaves us with a single benefit - affordability. That one is hard to argue.

At the end of the day, a Class D amplifier re-creates the analog sine wave input to it. Why do I want that when I can have the very same analog sine wave (not a re-creation), just bigger, with any traditional Class AB amplifier? Maybe I want that because I can save a bunch of money over a similarly powered Class AB amplifier? Nah. Plus I don't see that in high end audio. What I see is manufacturers charging good money for these new designs. Maybe some of that covers R, D, and E. Maybe some of that is just good old - hey, we can make this amp for less and sell it for the same money.

Furthermore, Class D amplifiers have filters between the output devices and loudspeakers to eliminate byproducts of the process in recreating the sine wave. A big passive filter. No thanks.

The parallel I've always drawn is a photo of a photo. Why do I want a photograph of of a photograph, no matter how close to the original it may be, when I can simply have the original photograph? Ten years from now, I'll still fell the very same way.

 

[twiiii]

I am known to be wordy, but the previous writer says it all very well and very accurately.

 

[Kevin M.]

Interesting. I worked for Rockford Fosgate when class D was all the rage in car audio amplification. The promises were great - small size, less heat, less manufacturing cost, lower price to the consumer. All good things in car audio. [Prior to the introduction of the bd1000a1, the Power 1100a2 was nearly twice as much money.] When Class D first came on the scene in car audio, the efficiency approached 75%. As I left Rockford, efficiencies were approaching 85% and full range Class D was in vogue. We did lots of listening tests between full range Class D and Class AB amplifiers and at the time (as late as 2008), Class D just couldn't compete in the SQ arena. Now, nearly a decade has passed and the technology continues to mature.

When it comes to home audio, I've always looked at it like this - what is so compelling about the promise of Class D that would make one abandon their Class AB amplifier in favor of it? Weight isn't really a factor - you set it on a shelf and forget it. Efficiency isn't really a factor - most sane audio folk have one amplifier or a pair of mono blocks (and not 1,000 wpc either). Heat isn't really a factor - Class AB amplifiers really aren't reputed as running awfully hot . . . say like a full Class A design. OK, sure - it's nice to be able to use Class D amplification for powered subwoofers for all of the same reasons that are attractive in car applications. That leaves us with a single benefit - affordability. That one is hard to argue.

At the end of the day, a Class D amplifier re-creates the analog sine wave input to it. Why do I want that when I can have the very same analog sine wave (not a re-creation), just bigger, with any traditional Class AB amplifier? Maybe I want that because I can save a bunch of money over a similarly powered Class AB amplifier? Nah. Plus I don't see that in high end audio. What I see is manufacturers charging good money for these new designs. Maybe some of that covers R, D, and E. Maybe some of that is just good old - hey, we can make this amp for less and sell it for the same money.

Furthermore, Class D amplifiers have filters between the output devices and loudspeakers to eliminate byproducts of the process in recreating the sine wave. A big passive filter. No thanks.

The parallel I've always drawn is a photo of a photo. Why do I want a photograph of of a photograph, no matter how close to the original it may be, when I can simply have the original photograph? Ten years from now, I'll still fell the very same way.

Excellent post! If you are a Mcintosh fan, you know that many have long held beliefs about the brand even though the newest amps depart from the traditional Mcintosh sonic signature. I'd ask you to keep this is mind with the Hypex stuff. Don't let your past experience allow you to form a complete opinion. Prior to my listening with the the Prometheus, Class D was not high-end audio IMO. This time, it is really a lot different, A LOT DIFFERENT.

However, getting to hear a Theta Prometheus is almost impossible unless you are prepared to buy one or have an owner willing to allow you to come to their home to hear it. Theta has lost most of it's "brick and mortar" dealers. Mcintosh has a lot of local dealers. Magnolia Hifi at Best Buy even has Mcintosh gear at a lot of locations. It's not hard to get an audition of Mcintosh gear. It's not hard to get service. Resale is second to none.

Do not underestimate the new Hypex amps. Mcintosh will still win a shoot out, but don't think it's not a "dog fight." I would have never made such a statement about class D before now. NEVER. At some point when faster switching transistors are available, Class D will be truly viable. Many who are not limited by financial considerations have indeed chosen the Hypex amps over well regarded class AB amps. I am not in this camp. The Hypex based amps are formidable amplifiers. They likely are the beginning of the end for Class AB as LCD and such flat screen technologies were for CRT television. That day is not this day however and traditional amps still reign. I doubt I'll ever buy a Class D amplifier because I don't think the technology will advance enough before I retire. It is for the first time, now a truly interesting discussion.

 

[MACKIE1975]

McIntosh own Audio Research

 

[for_p1]

Excellent post! If you are a Mcintosh fan, you know that many have long held beliefs about the brand even though the newest amps depart from the traditional Mcintosh sonic signature. I'd ask you to keep this is mind with the Hypex stuff. Don't let your past experience allow you to form a complete opinion. Prior to my listening with the the Prometheus, Class D was not high-end audio IMO. This time, it is really a lot different, A LOT DIFFERENT.

However, getting to hear a Theta Prometheus is almost impossible unless you are prepared to buy one or have an owner willing to allow you to come to their home to hear it. Theta has lost most of it's "brick and mortar" dealers. Mcintosh has a lot of local dealers. Magnolia Hifi at Best Buy even has Mcintosh gear at a lot of locations. It's not hard to get an audition of Mcintosh gear. It's not hard to get service. Resale is second to none.

Do not underestimate the new Hypex amps. Mcintosh will still win a shoot out, but don't think it's not a "dog fight." I would have never made such a statement about class D before now. NEVER. At some point when faster switching transistors are available, Class D will be truly viable. Many who are not limited by financial considerations have indeed chosen the Hypex amps over well regarded class AB amps. I am not in this camp. The Hypex based amps are formidable amplifiers. They likely are the beginning of the end for Class AB as LCD and such flat screen technologies were for CRT television. That day is not this day however and traditional amps still reign. I doubt I'll ever buy a Class D amplifier because I don't think the technology will advance enough before I retire. It is for the first time, now a truly interesting discussion.

Most today's D class amplifier are similar to DSD DAC. They just operate an high power levels. But all of them have switching frequency below 500kHz. Would you rave about DSD if it used 500kHz instead of 2.8MHz sampling rate? Class D amplifiers do get better, but they will still be a compromise unless switching speed reaches at least what DSD encoding is using. This will not be cheap though as it will look much more like RF device than audio amplifier.

 

[damacman]

The main difference between digital formats and digital amplification is that digital amplification doesn't bring anything to the table in the SQ department. At best, it can only be a very close approximation to the original analog signal input into it. OTOH, digital formats offer increased dynamic range, lower noise, etc. over their analog counterparts. That's what I don't get when I read the reviewers opining about Class D in the major publications - "This amplifier sounded so realistic, I thought I was listening to my Krell." Why not just listen to the Krell to begin with? Is it broken?

Alas, there are some folks that are currently streaming an MP3 (compressed) via Bluetooth (more compression) and amplifying this via Class D power. That's like having your friend snap photos of paintings at the art gallery, text them to you, and then viewing them on your phone. These very same people will exit the hobby in a year or two because it never really meant that much to them to begin with. Or, they go to a friend's to hear what all the fuss about records is all about and leave with their jaw on the floor. Then, the hobby stands a chance with their dollars.

 

[ossidian]

I owned a pair of MC601 amplifiers. I liked them but found them a little boring. I agreed to sell a pair of Avalon speakers to a local buyer last year who touted the huge improvements in new amplifier technology in Class D designs. Being a senior engineer "he" understands specs are everything, his words not mine. After a lengthly discussion I simply invited him over to bring his "incredible" Class D amplifiers. I played his Class D amplifiers and my MC601 amplifiers, at the end of the day he not only bought my Avalons but bought my MC601 amplifiers LOL. Win win for both of us. Oh, he sold his Class D amplifiers, so he told me.

 

[MACKIE1975]

Audio is a niche market and non-advance science or technology.

 

[damacman]

I owned a pair of MC601 amplifiers. I liked them but found them a little boring. I agreed to sell a pair of Avalon speakers to a local buyer last year who touted the huge improvements in new amplifier technology in Class D designs. Being a senior engineer "he" understands specs are everything, his words not mine. After a lengthly discussion I simply invited him over to bring his "incredible" Class D amplifiers. I played his Class D amplifiers and my MC601 amplifiers, at the end of the day he not only bought my Avalons but bought my MC601 amplifiers LOL. Win win for both of us. Oh, he sold his Class D amplifiers, so he told me.

My point exactly!

 

[c_dk]

How about a vacuum tube class D amp......I am sure there is a RF transmitter tube with enough bandwidth......the ramp up and ramp down might even provide some pre brickwall filtering!

Of coarse the stray RF might overload all the cell phones in the area and block big brother from monitoring you via your microwave.

There has always been "new" tech amps going to replace the proven tried and true for a lot less money. Heck many, maybe most in this forum believe or at least wonder if all went down hill with semiconductors.

 

[barsur]

Dear Kevin,

I cant comment on your Theta Prometheus Class D amp, but we did blind testing of the Mcintosh MC 601 against Sony TA-N 88, Sony TA-N 900 and Audio Research DS 225. All three are class D amps. Sony TA-N 88 was the first class D amp in the world.
What should I say, all three class D amps were no match at all for the Mcintosh amp. They almost sounded "wrong". I think this result happened, because we were listining to a very demanding speaker, the Linn 242 Mkiii. This speaker has an impedance of 2.8 Ohm to 16 Ohm and a phase change of 30 to -60 degree. Class D amps doesn´t like these changes of impendace and phase.
With an Harbeth P3ESR speaker we got by far better results for these class D amps. There was almost no difference to the Mcintosh MC 601. Why?! Presumably because Harbeth P3ESR is a very flat 8 Ohm speaker.

So all the judgement of your amps - especcally for class D amps - depends always with which speaker and in which room you are listining.

Best regards

Martin

 

[Velocityboat]

Dear Kevin,

I cant comment on your Theta Prometheus Class D amp, but we did blind testing of the Mcintosh MC 601 against Sony TA-N 88, Sony TA-N 900 and Audio Research DS 225. All three are class D amps. Sony TA-N 88 was the first class D amp in the world.
What should I say, all three class D amps were no match at all for the Mcintosh amp. They almost sounded "wrong". I think this result happened, because we were listining to a very demanding speaker, the Linn 242 Mkiii. This speaker has an impedance of 2.8 Ohm to 16 Ohm and a phase change of 30 to -60 degree. Class D amps doesn´t like these changes of impendace and phase.
With an Harbeth P3ESR speaker we got by far better results for these class D amps. There was almost no difference to the Mcintosh MC 601. Why?! Presumably because Harbeth P3ESR is a very flat 8 Ohm speaker.

So all the judgement of your amps - especcally for class D amps - depends always with which speaker and in which room you are listining.

Best regards

Martin

I agree but will say same holds true for any amp not just class D. I have compared Yamaha PC 2602 Class AB to McIntosh mC2500 to Lyngdorf PC2200 Class D. Things are relatively even until after 150 or 200 watts then the Mcintosh MC2500s in Mono really shines. With a lesser Mc amp maybe not. I was driving 4 ohm and 8 ohm loads XRT20 and XR19 stacked and XR290. The Yamaha drives XRT20 solo really well as will the Lyngdorf. Driving over 40 drivers a side bring major current 55 amps or more that means big mono blocks.

 

[ossidian]

Dear Kevin,

I cant comment on your Theta Prometheus Class D amp, but we did blind testing of the Mcintosh MC 601 against Sony TA-N 88, Sony TA-N 900 and Audio Research DS 225. All three are class D amps. Sony TA-N 88 was the first class D amp in the world.
What should I say, all three class D amps were no match at all for the Mcintosh amp. They almost sounded "wrong". I think this result happened, because we were listining to a very demanding speaker, the Linn 242 Mkiii. This speaker has an impedance of 2.8 Ohm to 16 Ohm and a phase change of 30 to -60 degree. Class D amps doesn´t like these changes of impendace and phase.
With an Harbeth P3ESR speaker we got by far better results for these class D amps. There was almost no difference to the Mcintosh MC 601. Why?! Presumably because Harbeth P3ESR is a very flat 8 Ohm speaker.

So all the judgement of your amps - especcally for class D amps - depends always with which speaker and in which room you are listining.

Best regards

Martin

My girlfriends clk320 performance at 55 mph is very similar to my SL65 AMG. Once I hit sharp turns or drop the hammer the similarities end-quickly. Persons who buy McIntosh or any other high quality amp expect performance not limitations like needing ruler flat 8 ohm speakers to sound right. If one buys a 300B amp they understand based on power the speakers choices. Buying a high wattage Class D amp that promises performance at less cost but limits your speaker choices (very, very few speaker manufactures make a flat quasi-variable 8 ohm) is compromise not performance.

And to damacmans point regarding analog amps vs digital amps using the snapshot analogy is spot on.

Is The Brain Analog Or Digital?

That mystery is revealed when we listen to music on a vinyl record versus listening to a digital reproduction on a CD or iPod. There is a difference between the two experiences.

Vinyl records are analog. The music is an exact replication of the live session because sound waves physically impress themselves on the recording medium.

Digital recordings take the live session and translate it into a series of bits.

The gathering and interpretation of those bits require an intermediary. A mathematical translation. A simplification.

When something intervenes with the original reverberations of the notes then a part of the music is lost.

Analog is a physical impression of the original. There is a direct link between the live performer and the recording.

Digital is an abstraction. The link between the live performer and the recording has been severed. The connection is lost.

The human ear is analog. Sound waves strike the eardrum, causing it to vibrate. The vibrations are passed to three small bones in the middle ear, which transmit them to a series of tubes. Within some of those tubes are tiny hair cells that pick up the vibrations and convert them to nerve impulses which the brain interprets as sound.

What is still up for debate is whether the brain's interpretation of sound is an analog or digital process.

Does the brain sever the link with the live performance when it converts the physical impression of music to nerve impulses? Are nerve impulses an abstraction in the same way digital music is a series of 1s and 0s?

Or does the brain keep the physical impressions in tact as it interprets the sound?

The Art and Science of Spontaneity argues that the brain is analog:

"No one would deny that our sensory organs are analog: sound waves and light waves impress themselves on our embodied mind in much the same way that analog recordings and photographs are made.

However, even the "higher" regions of our brain, like the cerebral cortex, look a lot more like an old eight-track player than my iPhone.

The neural architecture in the cortex seems built to manipulate two-dimensional, imagistic maps rather than digital symbols.

There is also a huge and constantly growing body of experimental evidence suggesting that the way people actually think looks imagistic rather than abstract. We think of our lives as journeys, reason about fairness by drawing upon physical balance, and viscerally experience evil as darkness or pollution, good as light and purity."

I am in the analog camp. The sounds and images I experience impress themselves upon me. They change me viscerally. Imprint my soul.

I believe there is direct link between a phenomena and how I see, hear and feel it. The connection is not severed by my brain nor is the experience manipulated into abstraction.

I'll stay in the Analog camp.

 

[ossidian]

Just because you think the brain is analog, does not mean it can't deal with digital. I think it all depends.

There are some fantastic digital amps out there. My friend has an Audio Research DS-225 and is using it with a pair of Wilson Sophia II's. It is a very stealer combo and these are 4 ohm speakers too. His room is acoustically one of the best I have heard and that may be a huge part of the equation that most people don't add in to the equation.

The latest scientific studies say so. I never said it can't deal with digital, it processes it differently based on the latest scientific studies by my colleagues. We speak in analog, ears are analog, what's up for debate is the processing. Some might prefer digital.

 

[ossidian]

You stated we can't deal with analog, not me. Again the fact remains (rooted in science) that the brain processes digital differently from analog.

I enjoy the debate. I welcome all comments. Getting easily upset is a strong indication of weak intelligence. I am glad you have engaged In a civil debate. I respect all points of views.

 

[4-2-7]

Being a senior engineer "he" understands specs are everything, his words not mine.

In the immortal words of Daniel von Recklinghausen, if it measures good and sounds bad it is bad. If it measures bad and sounds good you've measured the wrong things.

 

[ossidian]

My colleague interpreted the data based on every conceivable (not all-some not known certainly) known and theorized pattern, format into human thinking in relationship (directly/non-directly) to hearing.