And the plot thickens.
Al.
Juhleren is online now Juhleren Denmark
diyAudio Member
Join Date: Mar 2011
Quote:
Originally Posted by waltzingbear View Post
Maybe I'm missing something here, but we can't have it both ways.
If the amp sees half the load, say 1.7 ohms instead of 3.4 ohms, it will potentially become current starved before the single amp configuration at the same volume level. Its not that the amp is any less capable when bridged, its that it sees half the load value. I'm not concerned with the voltage limiting, until someone measures and says they have peaks exceeding +/- 65V longer than 2 sec, I don't think voltage clipping is an issue.
Current is what I am referring to. The Ncore is rated into 2 ohms, how much below that I do not know. But we already see it sagging at 2 ohms. Current limiting is irrespective of voltage level (until we get to SOA concerns, which are negligible in class D amps)
Hence my comment that a single amp is better at delivering the power to the speaker within its voltage range. Yes, this is less than peak power with bridged amps, but I don't care about peak power, I care about current delivery in the area of concern, during the time it is below the voltage limitations of the single amp.
Does that make my view point clear?
Cheers,
Alan
Yes, you do seem to only look at one amp (one half of the bridge) and not the bridge as a whole (being one amp on the "hot side" and one on the "cold side" of the speaker).
One amp (one side) sees only 1,7R of 3,4R total but also only delivers half the voltage swing (for the same output power and current as a non-bridged amp would).
That means that a bridged amp can deliver as much power and current, but at only half of the voltage swing seen from each "amp" in the bridge.
Together they deliver the same total voltage swing and the same total current as a non-bridged amp would. The bridged config can´t deliver more current, but then it doesn´t have to either.
Lets take a quick n´dirty math example to make my point more clear:
non-bridged:
3.4R x 24A = 81.6V peak (this would in practice result in clipping due to the max 65 to 72V supply limitations, but if we overlook this we would end up with-> 81,6*24 = 1958.4 W peak and 979,2 W RMS both at 3,4R)
Bridged:
only one module:
1.7R x 24A = 40.8 V peak
both modules in the bridge will then deliver: 2 x 40,8V = 81,6 V peak
One module delivers +40.8V and the other -40.8V = total voltage potential on the terminals being the 81,6V
This then provides the 1958,4 W peak and 979,2 W RMS well within the voltage limits of 65 to 72 V per module
In comparison one module with one smps600 should according to the +/-65V "only" be able to deliver 65/3.4R = 19.12A which gives 19,12 x 65 = 1242,6 W peak and 621,3 W RMS @ 3.4R
The bridge is according to the math more powerful in a 3.4R load.
The point at which the bridge is only equally powerful to the non-bridge is in a 65V/24A = 2.7R load.
Hope that helped
cheers,
