450 Pound Monobloc Amplifier

Mitch4t, the size and weight of the heat sinks on the Rowland 625 and 725 series amps are used to dissipate heat from the power output devices and are necessary due to their operation in a high bias Class A/B design. It is a common misconception that all amps using switched mode power supplies are Class D, while the type of power supply design and the bias/operation of the output stages are two completely separate design choices. A power amp with a switching output stage (also called Class D) is a highly efficient design that does not generally require large heat sinks for the switching output devices. When an amp design uses a Class A or A/B output stage large heat sinks are generally needed to dissipate heat from the output devices, regardless of the power supply design type. Hopefully this helps to clarify the issue. Good listening to all!

It's like buying a Mack truck to drive two blocks to the market. Silly, but sort of interesting.

People believe that the main reason for switching power supplies is efficiency and size while they produce noise (tradeoff). In reality switching power supplies executed properly allow to reduce noise. For that reason Rowlands Capri preamp is powered by switching power supply (where efficiency is not important)

Yes, switching power supply is the same as class D. In fact class D was invented when engineers who designed highly responsive switching power supply showed responsiveness by making power supply to play music.

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Guido....class D or not...the switching power supply is what makes the amps able to be much smaller. That is the real point here...the ability to get good power in a smaller package.

I see that the Rowland has substantial sized heat sinks relative to the overall chassis size. Why would an amp with a switching power supply need heat sinks like that? I thought one of the main advantages of switching power supplies was a great reduction of amplifier heat.
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Hi Mitch4T, all current Rowland amps and pres are based on switch mode power supplies (SMPSs). However this does not mean that the amps are necessarily running in class D. For example, look at the specs for M625 stereo and M725 monos...

http://jeffrowlandgroup.com/kb/categories.php?categoryid=203

and

http://jeffrowlandgroup.com/kb/categories.php?categoryid=208

G.

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Highly efficient, compact, light weight, 1500 watt DC switch-mode power supply provides optimum voltage regulation for all circuits and operating conditions, and allows for quiet operation over a wide range of AC mains power sources.

Guido...above is the quote from the Jeff Rowland site regarding the 725 monoblocs. Is the power supply switching technology mentioned there similar to the class D switching amps? I've heard class D amps referred to as 'switching' amps. Is this Rowland a 'switching' amp? No big power supplies in the Rowland to be seen.

Looking at the naked chassis before the innards are put in the amp, it looks like at least 60% or more of the weight is solid aluminum billet chassis.

Click Here To See The Aluminum Chassis...(scroll down when you get to the page)
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Mitch4t, the 54Lbs per chassis amps from Rowland (M625 and M725) are running in class A/B rather than class D.

Mapman, there is starting to exist rumbllings that recent amp implementations based on new modules may constitute entirely different kettles of sonic fishes. Definitely, some formal comparative reviews of some such creatures would be welcome.

Mapman - this question should be addressed to more experienced Audiogoners who have chance to compare them at shows. I can only comment on technical merits.

Minorl1 - no tricks, just different technology. Transformer operating at high frequency can be 10x smaller. For the same reasons capacitors don't have to be large. Smaller caps work great for filtering of higher frequency while voltage stability is handled by regulation. In comparison traditional supply doesn't have any regulation (line or load) and operates at 60Hz. Both conditions require huge amount of capacitors to keep voltage steady under momentary load and to filter out low 120Hz.

One review of my class D amp praised it composure during music peaks (orchestra forte) - that's what load regulated supply brings. In addition so called linear supplies are in reality primitive switchers operating at 120Hz and polluting with high current spikes. Rowland switcher has power factor correction and presents resistive load with smooth current. Jeff Rowland perhaps explains it better:

http://jeffrowlandgroup.com/kb/questions.php?questionid=144

@ minorl,Thanks about the compliment to Dan D Agistino momentum amps,I want them or the stereo version,wow!,you and mapman had a very interesting conversation here!awsome!,the both of you seem to know alot about amps!and yes my class A krell 700cx that is more power than 700 watts a channel with my 6oms speakers that dip to 4 oms alot,does not even fase the amp at all!LOL!A extra house heater forreal!LOL!,The heat that the amp generates does not bother me,since I live in the south,I am use to the heat here in alabama!cheers!

I don't believe that an amp has to be heavy to sound good. But, I do know to get rated power over the specified bandwidth, you need a serious power supply supply. you can't get around it. Which means that the tranformers must be huge and heavy. Large storage capacitors aren't cheap for the higher rail voltages necessary and they are heavy also. There are "tricks" that some manufacturers use, but they are just that, tricks. However, that is not to say that lower powered amps aren't wonderful. They are. One just needs to be very careful as to what they will be driving and what amount of consistent power is required. I read a review about the Dan D Agistino momentum amps and I would love to hear them. This guy, knows his stuff. I bet they are really great.

I'm interested to see if Stereophile or some other independent publication puts the new Pascal Class D amp from D-Sonic on the measuring bench to see how it compares to recent better Icepower based amps in terms of frequency response/bandwidth.

The bandwidth limit causes phase shift in audible range possibly affecting harmonics summing. My amp, for instance, has -3dB at 65kHz causing 20deg phase shift at 20kHz. Mentioned Rowland model 725 has bandwidth of 350kHz.

In theory, I suspect the difference between best Class D and Class A amps may still be bandwidth, like Kijanki says. Those attune to things happening at the very upper frequency limits of human hearing are probably most likely to notice any difference there. But over time I suspect even that would become a non-issue as technology improves, unless there is some hard law of physics out there that imposes a barrier for the long term.

Some people argue that class D, as good as it is for the money, cannot really compete with best traditional SS amp. I can see that, especially with still limited bandwidth, but most of the weight is in the power supply that can be definitely class D (SMPS) since it is only holding steady voltage (much easier task than driving complex load with music signal). Rowland does it so why not the others? I think it is for three reasons:

1. Design itself is much more difficult than just
transformer+rectifier+capacitors
2. SMPS have bad rap from crude cheap computer applications
3. Audiophiles still believe that it has to be heavy to
sound good.

Third point is very important - why to design complicated light power supply when market believes that heavy=quality.

I think Mapman is correct I have not seen any shootouts of class D vs pure class A either tube or solid state.

"I would really like to see where the other big names like Krell, Pass Labs, Bryston and the others could take the Class D or switching technology in the future."

One thing sure about technology in general, things generally get smaller, cheaper and more efficient over time.

Another sure thing is there will always be early adapters. Those are often not the biggest names but rather smaller upstarts that have something to gain from change/innovation.

Over time, a true innovation will gain more and more traction. Eventually, the more forward thinking big boys catch on. Some never do. You know what happens to them, right? That's why technical innovation and those who can drive it are always in demand.

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Mark Levinson makes a switching monobloc, 500 wpc (8 ohms), but it weighs 150 pounds. Jeff Rowland, as mentioned above makes a 325 wpc (8 ohms) monobloc that weighs 54 lbs, probably 30 lbs of it is its heavy chassis.

I would really like to see where the other big names like Krell, Pass Labs, Bryston and the others could take the Class D or switching technology in the future. Even Audio Research has a switching amplifier. I'm sure if the brains of those companies pushed that technology forward, really high end sound would get more affordable.
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Guido,

How about the current generation Class Ds that have been out there for a while, Icepower-based, Spectral, others? That would be a good baseline for such a comparison to see if/how the latest gen has upped the ante.

I've probably read such things in bits and pieces from various sources in recent years, especially when I was researching my own hi power amp purchase a few years back (yes I considered big monster amps from Pass, Krell, and others at the time but had no desire to go that way if avoidable), but I do not recall any comprehensive "shootouts" from a single source.

Mapman, there is still less than a handful of manufacturers that are shipping amps built around the new class D technologies.... Merrill Audio, D-Sonics, Acoustic Imagery, and Mola-Mola. And reviews are still fewer than that.

Any mags or other "trusted" sources done any shootouts between the biggest monster amps and best of the much smaller Class Ds in recent years? Lots of good reviews for both camps, but how do they really compare sound-wise on various systems that can truly benefit from a lot of juice?

"Man, a 1500 watt Class-A amp must be one HELL of a home heating device!! Not to mention being able to cook yer bacon and eggs while listening to your system..."

Not to mention the power utilization even when not playing?

I guess Boulder is not a "green" company. No moss growing there!

If it catches on, world peace might be threatened. Where is 007? Tell him to withdraw from whatever he may be doing. Evil audio threatens!

My Class D Bel Canto monoblocks are each 8.5" (216mm) W by 3.5" (88mm) H by 12" (305mm) D. Weight: 18.5 lbs (9kg). 500w/ch. Very well reviewed. Still recommended by mags after having been out for several years. They sound as good as pretty much anything I have ever heard (I have heard a lot!).

David versus Goliath?

If I could pick a large heavy amp I would love to hear Ralph's (atmasphere) MA3's driving my soundlab M2's;has anyone ever heard the MA3's or these Boulders that are being discussed other than Stringreen's comment?

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The 450 pound Boulder monoblocs are small potatoes compared to
the 1,000 wpc Krell Master Reference monoblocs seven years
ago. The Krells weighed 680 pounds per monobloc. Boulder
managed an extra 500 wpc and are 230 pounds lighter, so
compared to Krell, it looks like Boulder found a way to make
the amps smaller and more powerful.
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Everything wrong with high-end audio, right here in the form factor of one amp.

Phil

The weight may be an unconscious attempt by the Boulder designers to maximize the iron effect as explained by the Iron Theory proposed by Jeff Lafortune.

The best amps I've ever heard were also some of the heaviest. This theory does not apply for women. Actually, the meanest were the lightest.

@ minorl,Hi,the new Dan D Agistino momentum amps are far superior than the boulder 3050 period!,do not take my word on this!,check it out yourself!,Dan is a legend!,A pioneer so to speak of,cheers!

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The Boulder monoblocs are $200k for a pair.
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My guess is if you have the money for the amps, they should give you red carpet delivery and setup to save the hernia.

Does that Boulder amp come with a good hernia surgeon?

The lighter amplifiers I have listened to are okay to great with efficient speaker loads at lower power levels. but, give them a difficult load or inefficient speakers and we have a problem. I prefer to not have to change my amps when I change speakers. Just me. When I move towards more efficient speakers, they better sound as good or better than the ones I now have and work well with my current amps. I can't see myself replacing all my equipment at one time. For me, I upgrade when I feel something is better than what I have sonically, I can afford it and I feel it is time for that upgrade. I am very happy with my system and amps although I have heard really nice amps, such as the Boulder amps and the Audio Research Amps, etc (there are more). But, jaw dropping differences? Well, no. Not jaw dropping. for me to upgrade to better amps, I would have to spend tons of money that I really don't think it is wise to spend right now. But, the Audio Research Reference 250 amps are really nice. I like the sound. So are the Reference 750 amps. It is also a long term issue with me for equipment. I know people that listen/demo once or twice and purchase, only to find out later that they should have listed/demo'd more before buying and they are really not happy with their new stuff over the older stuff. My favorite store in San Diego sells Audio Research, Krell, Boulder and many other amps tube and solid state. And they would let me take one home for a week or so to demo in my system before purchasing. 300 to 400 pounds would be a problem for me using my car, but it would be fun to find out.

enjoy

Minori,
What you wrote is sensible and based on experience. Have you had the opportunity to compare these newer light weight designs to the traditional premium heavyweight you described? The bottom line is the sound quality.
I'm not convinced that the lighter amplifiers have the same true drive ability with difficult loads and provide equal or greater sound quality(I could be wrong).
Regards,

Man, a 1500 watt Class-A amp must be one HELL of a home heating device!! Not to mention being able to cook yer bacon and eggs while listening to your system...

-RW-

Power supply, power supply, power supply. You can't get around it, unless you get creative with switching power supplies. you need massive transformers (very heavy) and if sophisticated, massive coils (also very heavy). Efficient heat sinking is also very heavy. For low power amps that drive efficient speakers, you can design power supplies and electronics to output low power 10-20 watts and not have to have extremely heavy equipment. but for the others that have speakers that are difficult to drive or if you are designing and building amps that are designed to drive just about anything at rated power over the frequency range, you are going to need massive, expensive and very heavy power supplies. You can't get around it. Go to Nelson Pass' pass labs diy web site and read his thesis on power supply design. Again as mentioned in previous posts, compare apples to apples. What are you trying to drive? what power do you need? how efficient are the speakers you want to drive? The speakers that I have are absolutely wonderful sounding and are still better now (new panels) than many of the top of the line speakers I hear today. But, they take serious power to drive them. the mid and highs are amazing, and with the electronic crossover adjusted just right, the bass is pretty darn good. But, again, I need serious amplification to drive them. I have heard the Boulder amps. in my opinion seriously over priced, but so is a lot of stuff out there. But, the Boulder amps are absolutely wonderful sounding. I'm still not quite there with the Wilson Speakers. I've heard the Boulder system into Winson Speakers and Audio Research amps into the Wilson Speakers, and both into other top of the line speakers and it isn't the amps. It is the speakers. I'll take Boulder or Audio Research amps anytime. The new Reference 250 amps are great. But, Boulder is stupidly overpriced. However, there are people out there that are willing to pay the costs. More power to them. Anyway, the weight of the amps really depends on what they were designed to do and drive and the power supplies and coils and heat sinks, voltage rails (solid copper) etc. incorporated accordingly. Hence, very heavy amps.

Just my Engineering/Audio experience.

enjoy

My Jolida does 60WPC at 50 lbs and I like it. I've seen those Boulder amps at Goodwin's and they're adoreable. I think anything that expensive should be gigantic as it makes the owner feel better about everything although I do want to see the video of the owner listening to them when they fall through the floor...somebody please make that video. Thank you in advance.

New 650W Rowland model 725 monoblocks are only 54lbs (including fancy heavy case milled of single billet of aluminum). The key is power supply. Rowland uses quiet switching power supply (SMPS) that provides line and load regulation while traditional supplies are not regulated at all, noisy and require huge amount of output capacitors to hold voltage steady, not to mention gigantic transformer. Transformers in Rowland SMPS are small because they operate at higher frequency. Transformer that operates at 100kHz can be 10x smaller than one operating at 60Hz. Rowland operates at 1MHz. In addition it provides power factor correction, meaning it presents itself as resistive load, while typical power supply takes current is narrow current spikes of big amplitude increasing requirements for cable gauge, wall socket quality etc not to mention radiated noise.

With all the advances in smaller, lighter-weight, energy efficient designs, great sound and digital technology, stuff like this seems ridiculous, but hey, it's only hernias and money.

You could probably dry your hair with the Boulder but you'd have to crank it up for a while first:)

My Krell 700cx weighs a cool 180 lbs out of the box!at 46 I can still move it if I need to,the amp is two mono amps literally in one chassis,two of everything!I can see why this weighs what it does,the transformers are huge to say the least!happy listening!

I have a 1500W hair dryer that weighs less than 1 pound. Doesn't sound that good though.

D-sonic and a few other manufacturers are an early adopters of new energy-efficient power conversion technologies recently developed by small Northern European companies such as Pascal, Abletech, and Hypex (Ncore). The new power conversion modules outwardly enable the implementation of physically small power amplifiers with very attractive price/performance ratios. It will be fascinating to observe if the new designs constitute a mere blip in the landscape, or if their underlying technologies are gradually adopted by a broader range of manufacturers with a variety of design/sonic philosophies and degrees of sophistication.

G.

The 30/30 is probably not quite that heavy - VAC lists weight in-box. I weighed my 70/70 - 93 lbs. Still heavy, but not like the CAT amps - 192 lbs. per chassis. I helped my friend lift his - Jeeeesus.

I hear ya Swampwalker, probably a lot like my BAT VK-75SE was. The weight is all in the transformers. I have to admit, as I get older the weight is a turn off. I'm struggling enough moving around my current 85 pound amp.

I don't think I would ship to VAC for repairs anyway. I'm lucky to have a very good local guys in Bob and Gary Backert of RHB Sound Dezign.

I heard those Boulders at a club event - into top of the line Wilsons....very disappointing.

Let me tell you, JMcgrogan2-If you get a Ren 30/30, be VERY careful moving it onto and off of a shelf. It not only weighs 100 lbs, the weight is NOT evenly distributed. Easy to have an accident and shipping it back for a repair is $$. Great amp, tho, if your speakers are right for it.

A 10 watt amp is fine as long s you have the appropriate speaker match, amp-speaker really is a marriage. I think you'll be very happy with the VAC Renaissance , those are timeless excellent sounding amplifiers. There're good and heavy due to big premium transformers and a very stiff power supply section.Good choice!
Regards,

I'll bet the metal casing alone weighs a couple of hundred pounds.

03-12-13: Charles1dad
105 lb 30 watt amplifier? I like that ratio, this amp probably sounds very good. What is this amp you're considering?

VAC Renaissance 30/30. I'm very tempted to try a 300B tube amp, but those 10 wpc amps scare me. My speakers are a steady 8 ohm load, 91 dB sensitivity. I know the 30 wpc may be pushing it, but some say that the VAC's 30 watts plays much louder.

Yup, The more a component weights the better is sounds don't you know.