Braz, I will definitely post any listening observations about the new JRDG amps when I get my hands on one. . . we'll see if it is a 625 or a 925. Guido |
Just dredged up some more info. . .
Corus is companion product of 625.
625 is not exactly a replacement for 312. The 312 amp -- which is no longer in production -- will eventually be replaced by a class A/B stereo amp called 825, for which there is no delivery date yet.
The current Criterion preamplifier is intended as a companion piece for the 925 and the future 825.
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Macro, The units at CES were powered, but not connected in system. FCS is still tentative. Power rating is still undergoing finalization. I source info from JRDG.
Claude, 312 is certainly a marvellous product, but it is now almost 4 years old. . . and nothing is static in our domain. We'll see what the new products do for living, regardless of underlying class of operation. G. |
Thank you Macro, your source is impeccable. . . I suspect this is just a matter of subtly different wording. . . not terribly important. . . truth is we haven't heard these devices yet. . . can't wait to find out how they sound. |
If they exceed the music performance of JRDG 312, currently my favorite amplifier regardless of underlying technology, I will be extremely impressed. |
Cappuccino, what design/sonic differences are there in the recent 301 amps vs the original series? I have heard that there some differences, but I do not know what these may be. Guido |
Cappuccino, in that case the more recent 301 batches must be quite special. . . as much as I found the original 302 lacking, I am still in love with the 312. But I'm looking forward to hearing the newest 925 in my own system. . . probably Q2 or Q3. We'll see what the newest design does for living. G. |
Braz, the 'device' is a power rectifier based on a technology called Active Power factor Correction (PFC), followed by a bank of capacitors for filtering furter the DC before the actual switch mode power supply. As far as I know, the technology is used only by JRDG and by Chapter Audio. I suspect it is a significant factor in the 300 series sweetness of sound. The new amps are apparently also using active PFC and SMPS, although the core of the amps is not class D, but class A/B. Guido |
Macro. . . I am glad that your case of audiophrenia is milder than most. . . may I ask you about PC-1. . . how has it affected 102 and Capri? I did prefer Capri without PC-1. G. |
Yes, Audiophrenia being the most virulent known form of audiophilia nervosa. See:
http://positive-feedback.com/Issue46/audiophrenia.htm |
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Mark, here is what I know about the control knob on Criterion.. . .
The knob first of all has 2 distinct ways of operating. . .
turning the knob adjusts volume for primary and secondary zones, right to left balance, input offsets, output offsets, menu scroll.
Pressing the volume knob utilizes the knob as a selector for entering menu mode and activating a selection.
I do not know what chip/module the volume control is based on, (it may be an HP part but I am not sure(, but it is an optically encoded system, therefore the knob can be rotated continuously clockwise and counterclockwise without ever reaching a stop position. When Criterion is turned on, volume is always at 0dB. The volume is speed sensitive: turning the knob slowly or pressing single taps on the remote control volume buttons changes volume in 0.5dB increments. . . rotating the volume control faster or holding down remote volume buttons changes volume in 1.5dB increments. . . the loudness range is 0dB to 99.5dB. Per my notes, precision/stability is said to be within 0.01dB. Furthermore, the volume control is said to cause the audio bandwidth to remain unrestricted at all gain levels, without the volume becoming a bandpass filter at low SPLs. Also when using the volume to change offset values, balance, and volume for secondary zone, the volume knob remains velocity sensitive.
It is my understanding that the volume control does not act on the audio section directly. . . The volume control is in the control chassis.. . it communicates with a microprocessor controller in the same chassis. . . when a volume change is requested, the microprocessor awakens a communication bus. . . sends appropriate control codes to the audio circuit in the audio chassis that alters the gain of the OPA1632, then powers down the data bus until new controls are required. So the controller is always offline, unless it is needed to change a preamplification parameter. . . and the change takes place in a fraction of a second.
From an experience point of view the volume control is extremely quiet. it turns with a little less friction than on Capri. I can hear very soft volume change clicks only when rotating the knob quickly beyond the 93dB mark on the display. . . which is something that I do only if no music is playing. The background noise is essentially completely quiet up to the top of the gain scale.
Let me know if you need more information. . . but this is all I know up to now. Guido |
mark, Criterion uses large scale integration for its optical volume encoder, rather than discrete components. The dynamic range of the Criterion circuit is expected to be much wider than in previous JRDG preamplifiers, including that of various versions of Synergy and Coherence. I am not sure about the part number / manufacturer of the volume encoder module. |
All, it looks like our Criterion and related products thread is back in business after a brief abscence caused -- no doubt -- by a minor quantum fluctuation in the probabilistic Landscape that powers the Multiverse. My thanks to all that contributed to the cloning of the appropriate superstrings that allowed the threads return.
Regards, G. |
Husk, I'll know more about Corus product availability in the next couple of weeks. . . but the prediction of 4 months out for Corus does not match anything I have heard this far from JRDG. Claude, Erick Lichte seems to be correct about Model 925 pricing, but pessimistic about product availability. . . His crypto-reference to audio jewelry is very cute. G.
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Found more pics of the new JRDG gear at:
http://positive-feedback.com/Issue47/ces104.htm
G. |
David, I do admit freely that there are a lot of amps with greater authority than 312. My old Rowland 7M monoblocks for example, had comfortably greater authority than 312. . . after all, 312 peaks at 40 amps for a fraction of a second, while the old 7Ms peak at 50 Amps continuous. Having said that, I really would love for you to visit my system and bring your Wadia player along for the ride. . . I am not at all experiencing shiness in the bass region, on the contrary. My room is relatively dampened. It may be a matter of different speakers, CDp, and cabling. . . or simply different personal preferences. And while I do listen to music at relatively high volume, I probably never get 312 to near clipping situations.
I found your observations about Criterion sound extremely a propos. . . 'majestic' is definitely one of its sonic attributes. . . . and it is rather unflappable even when it yields very high dynamic swings.
I found that 312 is very sensitive to power cords. . . including what it does in the bass region. This far, some of the very deepest and cleanest bass has been with Shunyata King Cobra power cords, and Furutech High Performance ICs and speaker wires. I have further found that good power distribution also contributes to a tuneful, deep, and linear bass performance. |
No, I have no delivery date on Corus yet. I will check again this week. Guido |
I have not had the opportunity of performing a side-by-side comparison with Burmester, Viola, or FM Acoustic. Any of these would make for a very interesting analitical review project. G. |
Hi Kclone, I will buzz the factory on Monday and will post what I hear from them. Guido |
Kclone, I have just checked with the factory, and Corus has not been released yet. I'll keep monitoring periodically. G. |
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Macro, did you mean. . .
My kingdom for a 'source'..... (grins)
But yes, JRDG parts and subassemblies are manufactured mostly by military contractors. Only final assembly is performed in house. |
All, here is a correction to information I have posted earlier, repeatedly. . . and ever incorrectly. . . apologies, my bad:
The upcoming Model 625 will be a stereo amp, NOT a monoblock implementation. It will apparently be the companion piece for the equally upcoming Corus pre.
As for various specs and availability, I have no further information. G. |
Hi Braz, Final Model 625 power ratings and related tech specs have not been published yet. We are all still waiting. Guido |
Hi Braz, my Criterion is doing very well and it's making wonderful music... And sends you his best regards. |
There is now a JRDG FAQ in beta state. The Criterion section has just over 130 entries. See: http://jeffrowland.com/knowledgemanager/categories.php?categoryid=25 |
Jackson, turning up volume to about 80 or more is normal on Criterion. At 80 you have not even reached unity gain.
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Husk, I have no direct experience with Corus. However, Corus and Criterion have very similar gain characteristics. G. |
Claude, I have heard such an unconfirmed rumor as well .... But I have no idea of what changes there might be in the aledged new Criterion version. Does anyone have any info? G. |
Hi Claude, your info and my own coincide .... I also heard about 725 towards year end, and 925 at an undefined time after that.
Guido |
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Rowland ships Criterion with 4 Delrin balls that connect the audio chassis to the control unit. Have you put all 4 balls in place?? There is no apparent rocking motion possible with my own Criterion pre.
For more detail, se the article on stacking the Criterion Chassis on the JRDG Knowledge base at:
http://jeffrowlandgroup.com/kb/questions.php?questionid=397
G. |
Ian, try to determine if perhaps one of the seats for the balls is slightly deformed.... slightly too deep or slightly shallow... or is slightly misaligned... At which point the best thing to do will be to contact the JRDG factory. G. |
All, it looks like Criterion is no longer shipping. The current Rowland flagship general purpose preamp is Corus. For single source digital-only applications, Rowland suggests that the Rowland Aeris DAC feeding an amplifier directly, may yield even higher resolution. I have not tried the Rowland DAC in my system yet, so I cannot supply any personal impressions on this device. |
Hi Mark, you are correct... Criterion was by far my reference preamplifier, and would still be my reference if I had a mixture of digital and analog sources.
But, as I use only digital sources.... and only one of them at that, Criterion was wasted... I now go directly from the wonderful Rowland Aeris DAC into the Rowland M925 monoblocks. The sound is fabulously resolving, fluid and immersive, and intensely lyrical... And the system is absolutely without any background noise what so ever.
Guido
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