MC-275 vs "The Beast" (OTL)

[Coytee]

I know the power rating isn't equal (75 vs 165)

With that said, anyone have any inkling how a 165 watt OTL might sound compared to a 100 watt McIntosh? (we can use the 2102)

I'm still interested in getting a higher powered amp other than the one I'm currently using. I was going to contemplate solid state, and still might (MC-352)

I must say I love the VERY sweet sound of the SE-OTL's the Transcendent's put out when bridged. I must also say I love the renewed life injected into the Khorns when they're hooked up to some fire breathing power. I DON'T like however, all the noise/hiss I get when at idle when using the ss amp I've got.

So I've opened my mind up to higher powered tubes (just missed an MC-275 on ebay by $40). When I thought of that amp, the OTL came back to my mind. Sadly, it's not very easy to audition something like this stuff and I am hesitant on shelling out over $3K for a "trial" without some kind of idea of what I'm getting myself into.

[JBryan]

Coytee,

Bruce doesn't do trials - it'd be more like a "roll of the dice" experience. Also, the Beast has just started shipping so the reviews haven't started coming in yet.

Still, I too enjoy the Transcendent SEOTL amps bridged at 4 watts/ch. The top end is a little sterile compared to say, a 45-based amp but the SEOTL is very fast and the extra damping on the bottom end makes for very tight bass. The amps are also some of the quietest I've heard- barr none.

The Beast is more powerful than the MC-275 and being an OTL amp, should be faster, more detailed and will cover the extremes better by comparison. The Beast purportedly measures less than 800 microvolts of noise and hum. That's very good compared to many SS and tube amps but your SEOTL has less than 200 microvolts. That alone would sway my choice but I'm not going the high-power route.

Finally, the Beast monos retail for $5K ($3700 as a kit) and a very nice example of the MC-275 can still be had for much less and while the Beast will most certainly lose value in the used market, McIntosh products in general and the MC-275 specifiaclly are collectors' items and will only increase in value.

And Bruce's designs somehow manage to look more "utilitarian" than the MC-275 and the like - quite an accomplishment in itself!

Have fun, Bryan

[JBryan]

If you're really looking into high-power amps and noise is a big consideration, I would suggest that you look into the digital offerings from Hypex, etc.

A Hypex UcD400 module puts out @300 watts into 8 ohms and the new UcD700 will do almost 500 watts (8 ohms). Teamed with a good power supply the noise will be less than 50 microvolts - you won't be able to tell whether they're on or not. Being about as efficient as a flashlight bulb, they put out very little heat and leaving them on 24/7 is no problem - in fact, this allows the DIY audio crowd to use large caps like Black Gates in the power supply for massive amounts of capacitance.

Without the limits (and expense) of transformers found on most amps, the Class-D amps' frequency response is tremendous (<10Hz to >50kHz).

If you have any experience with DIY, you can buy the modules and PS and put these amps together for much less $ than either of the amps you mentioned.

I wouldn't go so far to say that these are the best-sounding amps out there as once again, I think SET amps have more finesse and presence and the P/P amps offer a warmer presentation by nature but you may want to consider these while you wait for the Beast reviews to come in.

Have fun, Bryan

[sfogg]

"Without the limits (and expense) of transformers found on most amps, the Class-D amps' frequency response is tremendous (50kHz). "

Class D amps will have an output low pass filter on them though. That intentionally limits their frequency response to some certain point. This is a needed part of their design to convert the pulses to an analog waveform and to block out the switching noise.

Typical linear SS amps (not McIntosh) won't have transformers or filtering on their outputs. Some are *extremely* extended... one company rates their amps from DC to 1.8megahertz (+/- 3dB) for example.

BTW, the SE-OTL is pretty much flat out to at around 100kHz. I didn't test it higher then that though.

Shawn

[LarryC]

I DON'T like however, all the noise/hiss I get when at idle when using the ss amp I've got.

Most hiss I've had on K-horns is from the preamp, not the amplifier -- you might turn off or disconnect the preamp and see if that makes a difference. I know the BB Xtreme is a nice, quiet preamp in terms of its own noise level, so the Peach probably is, too.

A key to how much preamp hiss is propagated is the sensitivity of the amplifier, i.e., how much gain. A high-gain amp (e.g., 0.5 v in for 200 watts out) may not be a good combination with K-horns because it will magnify the preamp's noise level more. My current amps (which are OTLs, BTW) have a lower sensitivity, needing around 2.0 v in for 100 watts out, and that works better for me.

I couldn't find a sensitivity figure on the Transcendent site, but may have missed it. You might want to see if you can find out.

Larry

[Erik Mandaville]

Bryan:

Is that an Oris 200 you have on a K-horn bass bin? One of the reasons I bought La Scalas a few years ago was to use them with Oris 150s and my Lowther PM2As (possibly trade those up to 4As). I like the La Scalas so much I forgot about the Oris horns, but I'll bet they are pretty nice sounding set up as they are in your picture.

Erik

[JBryan]

Shawn,

I don't know why but the frequency response of the Hypex amps didn't make it on my post. What I wrote was that the amp's range is from below 10Hz to beyond 50kHz.

Good eye Erik!

The horns on top of the Khorn bass bin are actually the Oris 150, not the 200. I had every intention of using the 200 though because I believed that they would integrate better with the Khorn - or rather there would be no real benefit to using the 150 instead of the 200. I actually bought a pair of the 200s but a friend decided to try the Bastanis Prometheus open-baffle kit and offered to sell me his Oris 150 setup.

BTW, I still have the 200 kit should you ever want to give 'em a try.

Have fun, Bryan

[Erik Mandaville]

Bryan:

Cool! I have a friend in Germany, Peter, who was using SE OTLs plus Grounded Grid with the Prometheus speakers he built. He also recently finished a sort of second rendition of the Prometheus, and said it's amazing (although I can't remember now how it differed from the first edition). He also Mentioned some months back that he built or bought something along the lines of a Gain Clone for very little money, and was shocked at how good it sounded! I experienced that myself, particularly with the Teac digital amp.

I'm interested in how you're incorporating the Klipschorn woofer. Are you just using a passive low pass filter there? One of the really neat things about the Lowthers is the lack of crossover. I think combined with the right LF driver/cabinet, such as what you're doing, the results must be really excellent. Are you also using the longer phase plug on the driver? How do you find the high frequency response with the 150s compared to the dedicated tweeter of the stock Klipschorn? (sorry, lots of questions here!)

"I actually bought a pair of the 200s but a friend decided to try the Bastanis Prometheus open-baffle kit and offered to sell me his Oris 150 setup.

BTW, I still have the 200 kit should you ever want to give 'em a try."

That is very kind of you, Bryan! It's something I still think about from time to time, and almost bought a pair when Ron Welborne was selling the remaining inventory he had from Bert D. After that, I thought about using the Lowther on an open baffle over the La Scala, very similar to what Dick Olsher has done.

Very interesting setup!

Erik

[JBryan]

Erik,

The setup is still new to me and changes are inevitable but at the moment I am using either a pr of Transcendent SE-OTL amps (bridged, 4w/ch) or the Welborne Labs 45DRD monos. I believe you're familiar with both amps - at least I've read your posts regarding the SEOTL.

The Oris horns and AER drivers are driven open and the horn has a natural cut-off @150Hz (thus Oris "150"). The speakers are biwired and I'm using a 2nd order low-pass filter with a variable resistor to dial in the cut-off somewhere between 160-180Hz depending on the amp used. The signal then goes to the Khorn bass bin via a BD-30 digital amp (30w).

The combination sounds very nice and the Oris horn integrates well with the bass bin. Its only been a couple of weeks since I finished enclosing the BB in the false corners so I'll have to give it a while to sink in. My opinion so far is that the sound is quite full and the soundstage is larger than before. The AER driver sounds very smooth and detailed and it reproduces the higher frequencies quite easily. Since the drivers and horn came already assembled, I'm not sure which phase plug you're referring to but the one I have is @4" long and has a 5" crown attached.

I will eventually remove the variable resistor once I find the best xover point and I may try an active xover at some point. I tried stuffing the cabinets with a bit of batting material but that didn't turn out well. I also have a +100 watt digital amp based on the Hypex UcD180 module that I may use in place of the BD-30.

There's lots of adjusting and tweaking to do but so far I really like what I'm hearing. Thanks for your interest.

Have fun, Bryan

[Rivendell61]

Coytee,

I would 2nd Bryan's Hypex suggestion (in fact, I already did last month when I suggested the Channel Islands UcD amps in your thread).

He is right that they are silent: I get dead quiet when fully cranked on my Forte's.

They are very low distortion, very linear, with little speaker load interaction, etc. All of which lean them toward transparancy to source.

Dan Wright (of Modwright) says they are the best amps he has ever heard--and prefers them to his Atma-Sphere OTLs (also better than his Bryston, Threshold, Sim Audio W-3, etc).

None of which, of course, says anything at all about whether YOU would like them.....

Mark

--And they can be ordered balanced or unbalanced :-)

[Erik Mandaville]

Bryan:

"The AER driver sounds very smooth and detailed and it reproduces the higher frequencies quite easily. Since the drivers and horn came already assembled, I'm not sure which phase plug you're referring to but the one I have is @4" long and has a 5" crown attached."

That's what I've heard about the AERs from everyone who has compared them with the older type Lowther that I have (Alnico PM2As) I've never heard the AERs for myself, so just have no idea what the differences might be. Mine took literally hundreds of hours to loosen up. It sounds, too, like you have the longer phase plug.

I also listened to the Lowther/Medallion II combination with the SE OTLs I have built (not for myself), but never two bridged for high power monoblock use. What a wonderful combination that was -- really some of the best sound in terms of overall quality and tone that we have heard here. Same is true with the SE OTL on the Klipschorns. I'm not talking about slam factor, which is obviously more important for some than others, but just in terms of making music sound like music; especially with concern to acoustic instruments -- winds, strings, acoustic jazz, and so forth.

I can honestly say I miss having one of those 1.5 watt OTLs around here to listen to. With about the same output, the DRD45s were also incredible. I'm sure the Oris are lots of fun to listen to, and they do look really great on the K-horn cabs. I wonder if it might be possible to tilt them down just slightly. Do you find the horns tend to beam, and/or what is the off-axis response like?

Erik

[Erik Mandaville]

Coytee:

Agreed on the price of Bruce R's new amp. For a high power OTL, however, I guess it's not too bad compared to other OTL competition. I consider Bruce Rozenblit to be a talented and innovative designer, and having heard his Grounded Grid, SE OTL, and T16 in my system, can say with at least some confidence that the 'Beast' is most likely a superb amplifier. I certainly don't need that much power here, and in most cases don't listen to much beyond a single watt (usually even less than that). However, Transcendent Sound products are known for having extremely low noise floors, even with insanely efficient speakers like Klipschorns, Edgar Horns, Lowthers, etc. For a couple of big OTL monoblocks capable of 165 watts, the price is not out of keeping, IME, with many other available products. Still expensive, nevertheless....

Erik

[Coytee]

Erik, aren't you the one that built Daddy Dee's SE-OTL's ?? (that are now in my posession).

[Erik Mandaville]

Coytee:

I built one of them -- hope it's working ok!

Erik

[JBryan]

Erik,

I hate to keep hijacking Coytee's thread.

I am certainly enjoying the 2 amps with the Oris/Khorns. The DRD45 is the most fluid and natural, followed by the single SEOTL and finally, the SEOTL monos. The SEOTL has more bottom end and control in the bass. The bridged monos have over twice the wattage (although I wouldn't go so far as to describe them as "high power" ;-) ) and double the damping factor so they can produce pretty decent bass for a flea amp. Running that signal into the digital amp really tightens things up and produces the fast, visceral bass notes that are at times quite startling. I'm finally sure that I've bottomed out the Khorns! I'm going to listen to the 30 watt Gainclones for a while but I'm anxious to hear what the 120 watt Hypex amps can do.

The Lowther/Medallion are very nice indeed. They were one of the horns that impressed me enough to want to try incorporating a full-range driver with the Khorn bass bin.

If you really start missing the SEOTLs, I have another pair (don't ask) that I'm going to have to move out of here at some point. Let me know if you have any interest.

Thanks for the kind words. Have fun, Bryan

[JBryan]

Erik,

"I wonder if it might be possible to tilt them down just slightly"

They are tilted down - I placed the stands so that the drivers are on the same plane and then aimed the horns with a laser (maybe a bit anal). I think you might be able to see from the pic...

Have fun, Bryan

[Erik Mandaville]

Brayn:

Sure, I see that now. Hey, if the laser works for you, go for it! I used to use a handheld measuring tape to measure the width, height, and depth of the soundstage of my system, but that has gotten more complex now that we have a surround system. I just hold up the measuring tape against the 'sound' until it stops on each side, top-to-bottom, and front-to-back!

Wow, those false corners you made look nice, Bryan. As someone who has used high efficiency Lowther-type drivers for year, I am really curious about how that arrangement sounds.

Erik

[Erik Mandaville]

And Bryan:

"Running that signal into the digital amp really tightens things up and produces the fast, visceral bass notes that are at times quite startling. I'm finally sure that I've bottomed out the Khorns! I'm going to listen to the 30 watt Gainclones for a while but I'm anxious to hear what the 120 watt Hypex amps can do. "

Absolutely. Such low power amplifification (depending on who your are) can provide some great listening with such high efficiency horns, and they do so for virtually all the kinds and styles of music we listen to. No doubt that what you say is true about 'visceral bass' notes and higher power. At 10 times the output ability of our SET amps, the 3 channel Teac digital amplifier was really a sort of 'study' in extreme efficiency, low noise (save for a little more tweeter hiss), and clarity. In terms of sound alone, it was easily good enough to qualify as that elusive end-all amplifier. I enjoyed it tons!

But, what can I say...... There is something so alluring and captivating to me about vacuum tube electronics, triodes in particular. However, I recently purchased an old Baldwin PP 6L6 organ amplifier that had been modified by a friend of mine. It is not quite as powerful as the Teac, but is also a very good amp; and is capable of remarkable bass slam in our listening room. I've been using it as the main L/R amplifier in our surround system for the past several weeks. That said, I intalled the Mothsi2A3 over the black La Scala center channel recently (pretty cool visual statement IMO), and it sounds enormous. I will say that it does not have quite the tight control of bass of the higher powered Baldwin, but does very well with virtually all we listen to -- as also do the other SET amps we have. I may have the opportunity to listen to a pair of bridged SE OTLs in the near future, and I am very much looking forward to that.

The Moth was given a very good review from VTV magazine (Winter 2000) -- that also noted, in another article devoted to the Klipschorn that, "A good 2A3 amp is scary-good with a K-horn, and similar results can be had with 300B amps as well." (note: I provided a separate paragraph for this quote, so it's easy for those-so-inclined to copy and paste when they respond to this statement)[]

Certainly ANY choice of amplification is subjective, otherwise there wouldn't be any disperity or difference of opinion among music listeners. The on-going 'sketchy' area that I perceive has to do with proclamations of one kind (high power or low) being inherently better than the other.

BTW: I like the false corners you made for your Klipschorns!

Let us know how experiments go with the Hypax (think I have that spelled correctly....) amp.

Erik

Erik

edit: Erik, Erik?! I think you both need to learn to take turns! I've told you before we only need one 'Erik' at a time at the end of a post!

[Painful Reality]

The AER driver sounds very smooth and detailed and it reproduces the higher frequencies quite easily. Bryan

The AER are excellent drivers indeed. Since I got mine back in 2000, my pairs of Lowther EX2, Lowther PM2A and Reps R-1 never played again.

[Marvel]

The AER driver

sounds very smooth and detailed and it reproduces the higher

frequencies quite easily. Bryan

The AER are excellent

drivers indeed. Since I got mine back in 2000, my pairs of Lowther EX2,

Lowther PM2A and Reps R-1 never played again.

It's too bad they empty your wallet so quickly though.