Jeff Rowland Design Group


I want to say a good word for JRDG customer service. I own a consonance preamp that is now 26 years old. An absolutely wonderful preamp. Early one morning during a "late night" listening session I made a boneheaded move and while adjusting the line level gain, put that module back in the preamp one pin off. That module became toast as soon as I turned it back on. Duh. The following Monday morning I called JRDG and to my surprise was able to talk to Jeff himself. He looked in his inventory & was able to find another module for the consonance (a 26 year old preamp!) of which I bought instantly. It was shipped out that day & I bought another fuse to put in the preamp itself. Long story short, I couldn't get it to not blow a fuse instantly when powered up, so prior to putting in the new module, asked Jeff if the new module would fix that issue. He said the module would not fix that, so I packed the whole thing up & sent it to him for repair before messing it up any further myself. He received that preamp on a Friday & the following Monday his secretary called me and stated he had it fixed.There was an issue with the power supply (as well as the toasted line module). I received it today & it sounds better than ever. Again, mind you this is a 26 year old preamp that he apparently made a priority of to fix. The new upgraded module & power supply cost a few hundred dollars and his labor charge to check this preamp out & fix it, was minimal. He certainly wasn't prompted by financial gain to fix my mistake, much less make it a priority. That my audiophile friends is great customer service.  
boxer12
George,

625 S2 and 725 mono-amps...are they Linear Class-A/B amps?
Yes your right they do still make linear only in these two, pity they used smp power supplies with them.

Quote:
" I suspect that the signal-to-noise measurement could have been tainted by very high frequency noise generated by the 625 S2’s switch-mode power supply"

https://i.nextmedia.com.au/Assets/20170221014711_jeff_rowland_685_s2_power_amplifier_review_test_lor...

All the rest of their range are Class-D though.

Cheers George
08-11-2018 11:00pm

I was a big fan and owned many Rowland amps and pre-amps for a long time and ever since they went to the Class D - Power Correction Mode technology, in my opinion, they lost what one was beautiful sounding gear. Too bad as I was looking at their 625 amp and took a listen and to my ears all I could hear was that Class D sound.

The 625 and 725 are the only JR linear amps as riced1 pointed out, but what you may have heard from 625 was the (switch mode) smp power supply they both use, the artifacts could give you the impression that it’s Class-D. As they complained about in the above test I posted.

Cheers George
George,

I read the article you posted. I understand what you’re saying about the measurements, but the listening session comments ends with: "It will provide superb and neutral sound with cutting-edge resolution and micro/ macro dynamics across the entire frequency range… and do so while looking like pure supermodel gorgeousness." Of course everyone won’t come to that conclusion, but I’ve compared my 625 S2 to several amps in my system and I still have the 625 S2.
George, 
I love to compare different components in my system. Please recommend an amp to replace my 625 S2. It can't have tubes and must be below $20K. It will be driving my Monitor Audio PL500 IIs in a 20' x 26' room. I'll post the results. 
Take your pick, these designers below they will have something.
But for your speakers, I’m told they closely follow the impedance and negative phase angle of the PL300’s, and these speakers are not a very demanding load. worst is 4ohms from 70hz to 200hz. Even mosfet will do.(Pass) https://www.stereophile.com/images/1016MA300fig1.jpg

But I have a feeling this is a loaded question, to which you won’t be convinced, no matter who says what.


These designers are to me are still at the pinnacle of hi end amp design, and still use linear amps and linear power supplies for their "flagship amps".
Flemming E. Rasmussen Gryphon
Dan D’agostino Krell and D’agostino.
Nelson Pass Pass Labs PassDiy, Threshold
John Curl, Halo and other hiend old school Parrasounds
Jeff Rowland Design Group non class-d old school
Mark Levinson non Class-d
ect ect.

Cheers George