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Rowland 625 versus Audio Research DS450

I'm a big fan of Rowland Products. I heard the 625 at CES and was rather impressed by its huge solid soundstage, and the detailed yet mellifluous sound. I was rather depressed by the price tag. I was hoping it would be in Rowland 501 range.

I also heard the Audio Research DS450 with Magnepans at CES. While the sound was very relaxed and tube like, I didn't hear as much bass, as I would have liked. Perhaps it was the speakers or the recordings played?

I noticed both manufacturers avoided the term Class D or "Ice Module" like the plague. I think Class D has become a dirty word among some audiophiles...

Any other thoughts on how the sound of the Rowland 625 compares to Audio Research's DS450?

I would like to save up for one of them. The DS450 or even DS225 seem like they might be "better bang for the buck" (in relative terms). Appreciate your comments. Tks!
optimus

Showing 3 responses by kijanki

kijanki's avatar
kijanki
4,446 posts
 
Rowland 625 is not a class D amp. It is class AB design with no global feedback and SMPS supply.
kijanki's avatar
kijanki
4,446 posts
 
Optimus, I use model 102 and like it a lot. Icepower amps used by Rowland have SMPS that runs at about 50kHz providing regulated voltage. 625 has also SMPS of Jeff Rowland design that runs at 1MHz.
kijanki's avatar
kijanki
4,446 posts
 
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:

http://jeffrowland.com/knowledgemanager/categories.php?categoryid=17
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