Jeff Rowland

03-07-15: Kijanki
Ricred1, I stated 22% loudness increase, but it would be true for 2x loudness. I forgot that bridging doubles the output voltage, thus quadruples the power. In such case you can count on (substantial) 49% loudness increase. Speaker's minimum impedance remains the problem.

L=k^(1/3.5) where L=loudness, k=ratio of power.

L=4^(1/3.5)=1.49

Kijanki, that's not true over the entire amp power range, correct? it will be true for a small power output range until the amp runs into its max current capability. So, we'll see a 4X the power just for that small power output range.

when the amp output voltage doubles so does the current. So, you have 2X voltage & 2X the current & an increased heat dissipation (& maybe even amplifier catastrophic destruction).
Or, am i thinking of this incorrectly? Thanks.

always look up to Mr. Rowland.. (He's very, very tall :)

indeed he is. I met him at the 2013 RMAF - on Sat he was running the demos himself in the afternoon (had the 525 amp driving the Raidho stand mounts which were crazy priced). I'm tall but no comparison to Jeff Rowland himself....

Thanks Almarg for the feedback.
Thanks Kijanki for the feedback & some dope on how power supplies are spec'd. Lots of diff ways to specify a power supply & that adds to the confusion already prevalent in the audio community re. power amp output power, distortion & dynamic headroom.

Although for an 8 ohm load the OP's 525 comes surprisingly close to doing that, the 8 ohm ratings being 250 watts and 950 watts for stereo and bridged modes respectively.

Almarg, I might be reading this incorrectly but in reading the Pascal Audio S-PRO2 data sheet (link provided by Kijanki in an earlier post by him) I noted that the bridged mode (Pascal Audio calls this BTL mode) power output is 700W/ch in 4 & 8 Ohms using a 120VAC power supply. It's higher for a 230VAC power supply (that they use in Europe) - maybe the OP is using a 230VAC power supply?
Again, if I'm thinking of this correctly, in bridged mode this Pascal Audio amp module has quite a large output wattage that it can sustain given its 30A max limit. Some serious watts with current delivery to backup these watts....

I also noted that the max current from the integrated SMPS is 30A & if you read the amp specs, you will see that the max power is rated for a 2.7 Ohms load!! wow, this is the 1st time I'm seeing an amp manuf spec his amp for such a weird load. I did the math & voila what did I find?? At 2.7 Ohms load, the output current is 14.9A - exactly half of the 30A max. This made sense to me - 30A max, stereo amp module, therefore each channel gets 15A max. Hence the lowest load impedance it can drive is 2.7Ohms before the integrated SMPS runs out of current delivery capacity.

Thanks, Almarg, for confirming what I was seeing. What prompted me to go to the data sheet was the power output inconsistency I read @ the Rowland website, your post & my initial quick perusal of the S-PRO2 data sheet.

agree that the 30A is max implying RMS = 21.2A, as you wrote. 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)?
In bridged mode, the 13.2Arms must be the total bridged-mode current for *both* amps in the stereo module (700W, 4 Ohm load).
while in Stereo mode the current must be 5.5Arms from each amp (8 Ohm load, 245W/ch).
As you pull the amp out of bridged mode the speaker load doubles to 8 Ohms & the power output drops to 245W/ch.
Or, am i thinking of this incorrectly??

I agree - 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...