Matrix STR3000H in Dub Clash Scandal

I suspect certain people would be less quick to judge if you said "would an amp sound the same at lower levels with less output devices? I suspect it might, but I  might be wrong ..."  instead of stating it as a fact, and arguing the toss with experienced amp designers. 

At low frequencies, the peak current capability is what counts, and you would run into current limit problems a long long time before you got to overheat problems. You'll find that for driving large speakers (18", 21", with 4" voice coils) large quantities of silicon are what  count ... a 5kw amp running at 1000w sounds better than a identical topology 1000W amp at 1000W,  large quantites of silicon sound better. Fact. Proven more than enough times. The silicon in a quality  amp designed for use with large sub/bass drivers is capable of more power (in terms of thermal capacity of the devices) than it is rated for (or has PSU for) by a factor of 2 or 3 times .... its not there for output power, its there to provide  significant current capability into low impedances, with significant reactive content.  Go look at an impedance plot (both magnitue and phase angle) for a 18" driver on sub bass duty ... the impedance will dip from a nominal 4 ohms to less than 1 ohm at certain frequncies ... and this is where having large amounts of silicon pays off.

Damping factor and back EMF off the driver are significant issues in driving low frequency large speakers with a high  mms.   The damping factor would increase significantly, reducing cone control even at low powers. Damping factor is not solely dependant on voltage gain in the feedback loop. Current transfer capability plays a significant part too.

The cororally of this is that I have seen far too many attempts to adapt a hi-fi amplifier design to PA use, simply by bolting on more output devices, in the forlorn hope that it will scale up to a 1000W + capability. It doesn't work that way, which is why good sounding PA amps are not as common as you might have hoped.

I kinda like the look, simple, understated and here to do a job. At worst you could probably call it plain.

i quite like the "plain" front. you can put it in a rack with anything else and it doesn't look out of place.

teslaman wrote: cilla.scope wrote:   At low frequencies, the peak current capability is what counts, and you would run into current limit problems a long long time before you got to overheat problems. You'll find that for driving large speakers (18", 21", with 4" voice coils) large quantities of silicon are what  count ... a 5kw amp running at 1000w sounds better than a identical topology 1000W amp at 1000W,  large quantites of silicon sound better. Fact. Proven more than enough times.   Is there any literature to support this "fact"? I understand an amp needs to deliver the required current but provided the 1000W amp in your scenario is not clipping and is able to deliver the necessary current then I fail to see why it would definitely sound worse then the 5kW one. Is it not possible that the 1kW amp may have a better design, with higher open loop gain and a lower output impedance (better damping factor) and thus could quite possibly sound better? I think its quite possible.

Dougies Music wrote: why did this argument stop?

teslaman wrote: teslaman wrote: cilla.scope wrote:   At low frequencies, the peak current capability is what counts, and you would run into current limit problems a long long time before you got to overheat problems. You'll find that for driving large speakers (18", 21", with 4" voice coils) large quantities of silicon are what  count ... a 5kw amp running at 1000w sounds better than a identical topology 1000W amp at 1000W,  large quantites of silicon sound better. Fact. Proven more than enough times.   Is there any literature to support this "fact"? I understand an amp needs to deliver the required current but provided the 1000W amp in your scenario is not clipping and is able to deliver the necessary current then I fail to see why it would definitely sound worse then the 5kW one. Is it not possible that the 1kW amp may have a better design, with higher open loop gain and a lower output impedance (better damping factor) and thus could quite possibly sound better? I think its quite possible.   Sorry, I missed the point here! Damn the lack of edit feature!! The *same* topology 5Kw amp sounds better than its 1kW brother - I remain to be convinced on this, what is the reason? I can't simply accept more silicon = better performance. There must be a quantifyable reason and if both amps can deliver enough current and are running un-clipped then what can it be?? If you say it's down to damping factor then what would happen if this was made identical too?

Oh, sure, theres no reason a different design  smaller amp wont sound better , better, smaller amp wont sound better than a poorer larger amp .. but  we where talking about identical desin topologies.

lets say we have a 1Kw amp rated into 4R resistive,  at 1000W  I^2 R = 1000,  so about 16A ... so lets say it has enough silicon to manage 16A and goes into current limit above that ...  whats it going to do when it tries to drive into 3R and deliver 100W of output into a load presenting a 60 degree phase angle?  cos phi will be 0.5 ... so you already need 32A .. and into 3R (quite possible at certain frequnecies in a nominal 4R driver) .. 40A?

This is why you need more current capability than the basic power equation would suggest ... the impedances are not pure resistive and not a nice constant 4R either.  If you measure up the actual output current capaility based on the silicon of any decent amp, you'll be suprised at how many times overrated it is. Its not done for fun. AMp makers dont typically use more silicon than they have to for no good reason ...

Anyway, you go ahead and rip 80% of the output devices out of an amp and see if it sounds the same.