Rowland 625 is not a class D amp. It is class AB design with no global feedback and SMPS supply.
41 responses Add your response
Thank you for the clarification!
So the 625 actually could be a refinement/evolution of Rowland's technology from both the Model 10/12 Amplifiers with some technology (e.g. power factor correction) from the Continuum?
I'm a non-engineer, so it is not so clear (to me) what may be new in this amp (compared to previous amps). I really liked the Model 10/12 Amps, which they discontinued just before I bought 201s. I've heard some people still swear by Rowland's Model 8 Amps...
I cannot directly respond to your question, not having heard either amp, but it's interesting to see that ARC is finally building a no-global-feedback amp (the Rowland is, too). The analog power supply is another reason for hope.
Regarding Rowland, the Model 2/6/8/9 vintage is generally considered the pinnacle of his designs - they featured battery power supplies and outrageous parts quality that today's much smaller market could not support.
Hi Lougiants - I remember the Model 10's seemed more "lush" and tubelike, in comparison to the 201's. If there is one minor area lacking, the Model 10's did not seem to have as much bass control as the 201's.
I really liked "quickness", low level detail, mid-range and bass control of the 201's. I decided to go with 201's at the time, as I needed a meaty amp to control Thiel's. (And the 201's are nice and small...)
Hindsight being 20/20, I think I probably would have preferred the Model 10's (over the 201's) with a more efficient speaker. Subjectively, the 10's seem to have more "soul" or body than the 201's.
The 201's relatively is a more neutral amp, but nonetheless still musical. It's a matter of preference.
The 201/501's straight into the wall are heavily dependent upon the quality of the A/C for their sound, much more so than a traditional amp using an analog power supply, so it can be misleading to judge performance in a given system. This is the primary reason that Rowland uses power factor correction circuitry in many of his amps, and used to offer a stand-alone power factor correction device, the PC-1, as an option for the 201/501.
Raquel, Icepower amps by definition should be less sensitive to power line than linear supplies since SMPS are both line and load regulated.
In reality all supplies are switching only frequency is different. Linear supplies switch at 120Hz polluting mains with narrow current spikes while 120Hz ripple on the secondary (amp) side requires a lot of caps to clean it up. For that reason Rowland started using SMPS even in preamps (Capri) where efficiency is not important. Also newest Rowland class AB amps (625, 925) use switching mode power supplies. PC-1 is further improvement (energy storage) but main supply of voltage to speakers is SMPS.
SMPS got bad rap from cheap computer supplies but properly executed deliver great performance with very little noise (zero voltage, zero current switching). I'm not sure how Rowland made it at 1MHz since it is difficult to get good efficiency because of limited slew rate switching losses (but easy to filter and get very fast load response).
Rowland posted few articles/answers on switching power supplies:
Seems no one has pointed out a basic answer to the original poster's question about missing bass and the ARC/Maggie combination. Maggies are "bass light" which is why most Maggie users have ongoing discussions about whether or not to try and add a sub-woofer to their system. I was just listening to my 1.6s (driven by an ARC SP-8/150.2 combination) and going through that same discussion with myself. Granted, my vintage and "entry level" ARC components don't fall in the same league as the DS450, but I think the largest contribution to the "minimal bass" issue is the Maggies. Of course I'm a Maggie-lover, and willing to sacrifice the low end for the wonderful midrange, but that is another discussion.
I am barely familiar with this type of speakers. Are big Soundlabs bass light as well? And I never heard anyone complain about their midrange. Why are you so attached to Maggies? Something very special? If there is no good bass there is no foundation. Even if you only listen to solo guitar or singing.
I don't know about Audio Research but there are no bad Rowlands so if someone wants to choose the best for a particular application one has to try a few. Older Rowlands can sound deeper.
Classic Rowlands and 300 series Rowlands tend to have a 'meatier' bass than M625.... mostly because they impart a pleasing and ponderous whooliness to the midbass. Conversely, M201 and M501's bass seems a little light and 'non-denominational'. By contrast, The bass of M625 appears to be more pitched and musically coherent than what I have heard from Rowland M7, M201, M501, C500, M301, M302, and M312.
Optimus, you may want to consider the just released DS450M mono blocks from Audio Research. There power supply is overkill with over 176,000 microfarads in each amp. A serious brute. Audio Research never used Ice modules in the past, but did use Tripath modules, which is now out of business. All current class D products from Audio Research use their own made in house designed switching module. Class D has always got a bum rap since the first experiments started in 1958 with poor results. At the time, amps kept blowing up since they could not handle the large volumes of modulating current, until John Ulrick came along in 1968 and installed a class D amp in an active subwoofer when he owned Infinity. Audiophiles also need to understand that class D has nothing to do with digital whatsover, unless specified, it is nothing more than a category classification of an analog amplifier.
Optimus, you may want to consider the just released DS450M mono blocks from Audio Research. There power supply is overkill with over 176,000 microfarads in each amp. A serious brute. Audio Research never used Ice modules in the past, but did use Tripath modules, which is now out of business. All current class D products from Audio Research use their own made in house designed switching module. Class D has always gotten a bum rap since the first experiments started in 1958 with poor results. At the time, amps kept blowing up since they could not handle the large volumes of modulating current, until John Ulrick came along in 1968 and installed a class D amp in an active subwoofer when he owned Infinity. Audiophiles also need to understand that class D has nothing to do with digital whatsover, unless specified, it is nothing more than a category classification of an analog amplifier.
Optimus..looking more closely into the interior of the Audio Research DS 450M does not reveal very much make up such as extensive circuit boards and parts. A little on the skimpy side. A lot of caps and minimal board work. For $10K I wonder if one is paying more for a name than whats in the unit. Overall, the Bel Canto Reference 1000M MK.2 is the better value with more power at $ 6K a pair, and 500 watts rms. The Bel Canto peaks at 45 amperes and the Audio Research peaks at 35 amperes. The Bel Canto is on the warm side and I would think the AR as well since its voiced from their tube amps.
Audiozen, class D amps tend to achieve a high degree of circuit integration/miniaturization. While a very busy internal topology can yield a certain degree of pride of ownership all by itself, I much prefer to evaluate amps according to what they can do for me musically/sonically, rather than on the impressiveness of parts count.
The suggestion of evaluating DS450 against the well known and loved Bel canto ref1000M is an excellent one, as DS450's price tag fits somewhere in between Bel Canto REF1000M monos and Rowland M625 Stereo.
Specs alone suggest that ARC DS450, with 450W with 35A of peak current, might yield a larger stage and instrumental images than Rowland M625, which delivers a more modest 300W with a peak current of approx 20A. However, in the end, only sustained direct comparisons can tell the real story.
Optimus..Class D is a threat to a traditional transfer function topology that has been around for sixty years. Many of the established High End component companies are not in a position to re-format. If a class D product has a large enough power supply and high peak amperage, it will equal the best A or A/AB amps. Large volumes of current is what should be focused on. If a class D device can provide
the same volume of current on the long and short term as a 100 to 200 lb. conventional amp, then the class D amp is a superior product. The three best class D amps on the market are the Spectron Musician 111 MK.2 with the deluxe V-Cap upgrade, which is a second option over the standard V-Cap upgrade, which Simon can explain, the new Nuforce Reference 18's, and the Bel Canto Reference 1000M MK. 2..these amps have won the battle..Game Over....
Given the very diverse interpretations of the term "best" in the world of audiophilia, I suggest listeners interested in class D also may want to extend their audition at least to the newer H2O implementations, the now withdrawn Rowland M312, current/recent production Rowland M301, and of course the new ARC DS450. It is very difficult to tell a priori what sound may make a particular person 'click' into Nirvana, let alone declare the ultimate winner of the 'battle'. G.
Guidocorona..the two factor's I look at for class D is the ampere output, and the db level the amp can achieve before signal break up occurs. The Bel Canto's can be taken all the way up to 130 db's before strain occurs. That's damn impressive. Sonically, class D amps that have high DB and ampere numbers will always sound sonically superior especially on the bottom. The most exciting future class D product coming out in 2012, is the Wyred 4 Sound four piece mono amps. The goal is to top Bel Canto. The amps will be a separate mono chassis with a separate power supply foe each side. It will give Spectron a run for the money.
07-25-11: AudiozenI think you are referring to the dynamic range spec provided at the Bel Canto website, which is indicated as 120 db for the REF1000M.
That has no direct relation to maximum sound pressure level, which of course is speaker-dependent. It apparently refers to the ratio of maximum rated output power (1000W into 4 ohms, 500W into 8 ohms) to the power level corresponding to A-weighted rms output noise (90 uV).
Those numbers calculate, btw, to 117db of dynamic range into either load impedance, not the 120db which is indicated.
In any event, maximum sound pressure level in db should be calculated based on the maximum power rating, speaker efficiency and impedance, listening distance, and speaker wavelaunch characteristic (planar, box, line source, etc.). Dynamic range has no direct relation to that; it just indicates how far below maximum spl the amp's output noise level will be.
OK Al..Its my understanding the 120db level has nothing to do with SPL but the limit the amp can reach equivalent to the current output that equals a 120 db level. This has nothing to do with speakers, just the current level the amp puts out equal to 120 db's. Beyond that, the amp could not sonically perform.
My apologies. I had no idea this thread was revived in July!
- Audiozen, Guido or others:
Just curious, what are the key sonic differences between the Bel Canto 1000M and Rowland 625, other than raw power...?
I'd be curious if anyone has had a chance to listen to both amplifiers. Appreciate your thoughts.
Perhaps the 1000M is a bargain, in comparison?
Optimus, Bel canto Ref1000M and Rowland M625 are both magnificent amps... They are in fact among my very favorite amplifiers, and they both deliver their own special kind of musical grace, in a way that is largely consistent with their price difference... Perhaps they are both "bargains" in their own right.
However, I have not heard yet the new ARC DS450, monoblocks, and I am admittedly extremely intrigued .... as DS450 amps are priced exactly in the middle between Ref1000M and M625.
Appreciate your comments, as always. I have the Rowland 201 monoblocks. I like them, but my main complaint is they seem a little bit "sterile". The music seems to have less guts.
Just curious, do 1000M's seem to have "soul" like the Rowland 625's, which keeping the musical detail...? As far as you're aware, are there big sonic differences between the Bel Canto "M" and "non-M" versions? Tks!
Optimus, your findings of Rowland M201 are consistent with my own observations. M201 tend to run out of steam reasonably easily. They do also sound very clean, but in themselves, M201, which are based on the ICEpower 500 ASP modules, are not the most musically involving amplifier I have heard. On the other hand, Rowland M201 cannot really be compared to the Bel Canto REF1000M monoblocks (previously called REF1000 Mk.2). REF1000M use the much more powerful ICEpower 1000 ASP modules, also used in Rowland M501..... and I have NEVER heard any of them run out of steam, nor falling off in dynamics or authority.
Bel Canto REF1000M is a slightly warmer-sounding and more nuanced amplifier than Rowland M501, while Rowland M501 may edge out REF1000M in transparency and quiet background.
There are 2 versions of the Bel canto Ref1000 monos.....
The original REF1000 monos, which are the warmest, slightly less extended, and paradoxically have some minor jarring in the treble.
The REF1000 Mk.2, later renamed REF1000M, which are more extended than the original, not quite as warm, and and in my opinion yield a more musicaly satisfying and delicate treble.
Thanks Guido. I'll see if I can give the 1000M's a listen. It will be tough being in a small city, but maybe I can make it to RMAF this year...
Although I think many manufacturer's were attracted to the ICE modules because of their low power usage and cost effectiveness, I believe many found it (using ICE) to be a marketing nightmare.
Several companies had difficulty explaining why or how their ICE based amps were different from others, much less explain the price difference. To make matters worse, some audio magazines expressed an almost universal, perhaps irrational dislike for the "Class D" sound. Digital amps became a dirty word in some circles.
Maybe it's just me, but I noticed several manufacturer's seemed to have moved away from stating they use ICE.
This is or was unfortunate, because perhaps ICE could have raised the bar for affordable high power, low cost amps.
On my part, I try to be technology agnostic. In the end, hopefully, the proof is in the pudding or listening.
Optimus, the "negative reviews" on IcEpower are old hat.... they were covering early devices, that in some cases may not have been broken in adequately.
I hope you make it to RMAF.... you will discover that some designers like Stronczer of Bel Canto obtain from their ICEpower-based amplifiers a refinement of sound that comfortably exceeds any reasonable expectations from the particular price point.
I had the chance to hear the Rowland 625 for a second time, this time at RMAF 2011. I have to say this time I was a little bit disappointed. (The first time at CES 2011, I was wowed. Cannot remember the original setup.)
The Rowland 625 was setup with Thiel 3.7's Speakers, Rowland Aeris Dac (used as both DAC and preamp), and Bryston BDP-1 (Digital Player).
While it didn't sound bad, there seemed to be a "whitish" type high frequency coloration to the sound. There was much less mid-bass, than I would have liked. The overall sound was little bit "hard".
I was thinking that there may have been a few possible causes, assuming I listened correctly.
a) The 3.7's were not broken in yet.
b) The 3.7's sound is much better in a larger room,
giving the bass and mid-bass a chance to bloom.
c) The preamp section of the Corus is better and much
more forgiving than the Aeris DAC.
Any thoughts from others who were at RMAF?
I usually love Rowland and Thiel stuff, so I'm wondering how these hotel setups or demonstrations may effect the sound.
I heard the Bel Canto 500M's with the Joseph Speakers. It sounded pretty darn smooth...
Optimus, in the Rowland room I heard relatively similar things as you did. I am quite familiar with the sound of M625, Corus, and Aeris DAC in favorable setups, and they sound like completely different devices from what I heard at RMAF this year. Part of the issue may have been the speakers that perhaps were not ideal for the electronics, but I suspect the largest problem may have been overdampening of the room.
Conversely, I truly enjoyed greatly the sound of the room where the new Audio Research switch mode DS450M monoblocks were featured.
Guido, good to hear from you! For a while, I was worried that I was suffering from listening fatigue from the show, and hearing things. Yeah... setup seems to be super, super important. Even with the best gear, you can't always beat the room acoustics.
Vienna Acoustics Speakers, which I believe you may own, seem to have a pretty good synergy with Rowland. I think Rowland may have done a few demos with Vienna in the past.
I agree with you on the DS450M. They sounded extremely musical and dynamic. I honestly think we are reaching a point where amps (at a certain level/price point) may not necessarily sound better than the other. They simply sound different.
Just curious, what were your favorites from the RMAF show that really impressed you? (I'll probably try to start a different thread on this subject.)
I really like the Esoteric Dac's and CD players, albeit out of my budget. Is the K-01 or any of the other gear you liked at RMAF next on your review schedule?
All this is off topic -
What did you think about the M2 Tech Young 384/32 D/A Converter, which I believe was in the same room?
DACs in general seem to be better and better, and less different than each other with good source material.
I'm hoping they've refined the magic bullet of making bad recordings sound listenable...!
Optimus, let's return this thread to "its previously scheduled programming".... and then continue to talk about DACs on the Reference DAC thread at:
Where I am positive we will be able to raise some charming weather :)!