Jeff Rowland

03-10-15: Bombaywalla
Then, in bridged mode if each amp in the stereo module is outputting 13.2Arms that total is 26.4Arms which is greater than the 21.1Arms that the integrated SMPS is capable of supplying!! So, is the amp really able to output 700W into 4 or 8 Ohms in bridged mode (as in the spec sheet)?

I'm not 100% certain of this, but I believe the way to look at it is that since in bridged mode the two channels are operated out of phase with each other, and the load is connected between the two + output terminals of the amp, from the perspective of the power supply it is supplying 13.2 amps, not 26.4 amps, when supplying max rated power into 4 ohms in bridged mode.

In other words, the 13.2 amps that is flowing through one channel does not add to the 13.2 amps that is flowing through the other channel, because it is the same 13.2 amps!

While if both channels are driven in stereo mode the power supply would of course have to supply enough current to support the total amount of power being drawn from both channels. Note, though, that all of the output power ratings indicated in the module datasheet for stereo mode are based on only one channel being driven.

... all these numbers don't jive with each other further adding to the confusion of what the amp is really capable of power output-wise. in such a case, I'd be inclined to take a slightly conservative path & side with the class-D amp module manuf...

Agreed (except that strictly speaking I believe it would be "jibe," not "jive" :-)). Perhaps all that can be said with certainty is that this is a very powerful amp, but one which should not be expected to perform well when used in bridged mode with speakers having impedances which drop below 4 ohms at frequencies for which lots of power is likely to be required.

Best regards,
-- Al

Almarg,
I just want to reiterate how much you have helped. Simply moving bass traps solved my problem, that many people would simply blame on the electronics. You have indeed saved me from spending money on another JR 525 or a new preamp. I'm still listening to other DACs to see what improvements can be gained over my PS Audio Directstream DAC. Although I like bass, my priorities have always been what I consider a "natural sound", great spacing, and an open soundstage with good depth.

Glad I was able to help, Ricred, and thanks for the very nice acknowledgment. Enjoy!

Best regards,
-- Al

I moved the bass traps out of the room, put them stacked back in the corner, put two behind the listening position, with two in the front corners and after a whole day of listening decided that one in each front corner and two behind the listening position was best. No bass suckout, but more air and better imaging with two in the front(not stacked) and two in the rear.

Almarg- what is your thought on subs? I called PS Audio and they said I could control a sub through my Directstream DAC's RCA inputs, because my amp is connected via balanced cables. However their own literature says, not to connected both the RCA and balanced cables simultaneously. I want to try a JL F112, but don't want to purchase a preamp.

I'm uncertain as to how well connecting a sub to the DAC's RCA outputs would work. It would certainly function. But without clear information as to the design of the DAC's output circuits I would have some concern that doing so might have at least slight adverse effects on the signals provided to the Rowland amp, and thus to the main speakers, unless the circuits driving the two outputs are totally independent. That concern being heightened by the fact that as with the line-level inputs of most subs the input impedance of the F112's unbalanced inputs is low, in this case only 10K.

And I note that in the entire DAC manual the only statement that is bold-faced is "We do not recommend using both outputs at the same time."

And then of course there is the question of how good a match there would be between the sonics of the sub and the main speakers, about which I'm not in a position to comment.

Also, of course, there are other subs which provide speaker-level inputs, such as the RELs. However, the 525 amp is described as having "balanced topology implemented throughout all power and input/output circuits," which leads me to suspect that it may not be ok to connect the ground wire from such a sub to the amp's negative output terminal. And the amp does not appear to provide any other suitable ground connection point. In which case connecting that wire to a chassis screw on the amp would **probably** work ok, but again there is uncertainty.

Best regards,
-- Al