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In Reply to: Re: Rowland 201 vs 501 for MBL-121 posted by DevillEars on April 29, 2007 at 01:47:05:
Please excuce me.
Does the information of 35 A continuous for the 500ASP unit come from a reliable source?
If so even the 500ASP module based Rowland's Model 201 should drive effortlessly pretty much any speaker on the market.
I mean, 35 A RMS is an enourmous amount of current.
This topic is extremely interesting to me.
I feel that in the next future there will be more and more switching power supplies in audio power amps.Thanks a lot and kind regards,
Follow Ups:
Hi Beppe,The source of the specifications was B&O's ICEpower website and a downloaded product datasheet for this module.
I mistakenly added the word "continuous" - this is incorrect usage, as the 35 amp figure is, in fact, quoted as "Maximum current draw from amplifier output" and is, more than likely, the threshold setting for the on-board "Over-Current Protection" circuit.
Based on the Power @ Impedance values quoted of
a) 500 watts into 4 ohms: Current drawn = ~11 amps at ~45 volts
b) 250 watts into 8 ohms: Current drawn = ~06 amps at ~45 voltsBy extrapolation (no figures quoted in datasheet) values for lower impedance loads would look like this:
c) 1000 watts into 2 ohms: Current drawn = ~22 amps at ~45 volts
d) 2000 watts into 1 ohms: Current drawn = ~45 amps at ~45 voltsThe datasheet does quote the acceptable speaker impedance load range as being between 2 ohms and 8 ohms, but no figure is provided for rated power output into 2 ohms.
Given a maximum current level of 35 amps, any load less than 2 ohms is likely to pose a few problems.
BTW, I did include a link to the ICEpower website if you wish to dig any deeper.
Thank you very much for your kind and very valuable explanation.
I did listen the Model 201s (driven by a Jadis preamp and driving B&W Nautilus speakers) at an audio show in Milan some years ago.
I liked very much what I heard.
A nice clean relaxed sound. Very good indeed.Thanks again and kind regards,
beppe, do you feel that switching power supplies are better or worse?
My H2O amps use a linear power supply. Used in conjunction with carefully chosen attending components, the sound is utterly sublime. The same builder makes far cheaper ASP module amps. He will be the first to admit, the sound of the linear power supply amp is solidly better than that of the digital.
Well to be honest I am gathering information on the subject in order to try to understand better.
I notice that the very best power amp, at least in terms of driving ability, still have traditional linear power supply.Going back to the JR Model 201 I feel that the 35A continuous figure is optimistic.
I have at hand an Italian magazine with a test report of the Model 201.
I can see a graph of the power output showing about 18A continuous on a pure resistive 2 ohm load (648 W) and about 12A on a 4 ohm load (576 W).To end I really do not know if there is an overall better tecnology.
Maybe not. It could be just a matter of implementation, construction.Kind regards,
beppe
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