Calling out the big boys

Ok some of you may know that I am planning on investing in a Void infinite 8 MK1 (possibly MK2 if I get some more cash together)

It has been pointed out to me by another forum member that maybe this isn't the best decision. He advised one of the more renowned and classic work horses such as the Crest 9001 or the Crown Macrotech 5000vz.

I'm needing to run 4 - 2 x 15 Turbosound TSE copies. My thoughts were to save on weight, latency, complicity, power, cost and height in the rack.

Any suggestions or comments would be good, Rog maybe a bit of technical back up here and re-vitalise my confidence in the Infinite 8?

Cheers all

Wicked, cheers dude. Perhaps the advice was best, any Infinite 8 users wanna step up to the plate?

Can't comment on reliability but I've heard what the infinite 8 v2s can do, the noise they make and the juice they suck is frightening. I watched the current meter peak at 32 amps (UK voltage) then went outside at took my earplugs out. And readjusted my hair.

SteveAATW wrote: Thats another thing, in these days of us all being green and network operators being very resistant to installing new feeds anywhere are amps which pull this much really that practical?

All of us who love the big old amps, can't ignore this.

There are fewer and fewer buildings that can supply 220-240V @ 32 amps.

Loonie if you really must have 2ohms per side, you know which amps to look at.

If you want to be able to take your rig every where, 2x amps that can supply 1500wpc @ 4ohms would benefit you much more, and be more reliable.

Which means just buying another Network 4, would be job done.

Rog Mogale wrote: You can't get something for nothing and if an amp is only drawing 10 amps and it was an impossible 100% efficient it would be putting out 2300 watts. I can't see any way of putting in 2300 watts or power and getting more out.

I have stopped mentioning this in the amp forum, because everytime I did, someone would use the smoke and mirrors argument of, "Well music is not a continous sine wave, so most of the time you are not drawing full power".

I would prefer to pay for an amp, that is rated @ X kilowatts per channel @ 4ohms stereo/2 ohms bridged, and has manly enough PSU to draw the required current in the eventuality that continous performance to specifications is required.

Rog Mogale wrote: I don't get this. How can an amp put out 1,000's of watts but only draw 6 to 10 amps. That's like saying a 1Kw electric fire will only draw 2 amps, when we all know it should draw 4.34 amps if the voltage is 230 volts. The Infinite 8 v2 is nearly 90% efficient, which puts it up there with the best switch more amps that use a class AB or H output stage. If you see 32 amps draw on the front its because there sh*t loads of watts coming out. The big crest and crown amps are only something like 70 to 75% efficient, so if its 75% efficient then the amp will draw 8750 watts to put out 5000 watts or 38 amps. This is more that the 32 amps that the Infinite 8 v2 needs to put out lots more power than that. Are you starting to get it know. You can't get something for nothing and if an amp is only drawing 10 amps and it was an impossible 100% efficient it would be putting out 2300 watts. I can't see any way of putting in 2300 watts or power and getting more out. Its physically impossible and I think at the shootout we will really start to see some lies exposed if they allow it.  So can we stop saying the Infinite 8 v2 is power hungry, it's the most efficient transformer amp ever and if likes to consume a bit of juice is because there some real juice coming out.

It's about average power though isn't it, not peak. Intelligent switchmode power supplies can fill their resevoirs in a much more controlled manner than a linear with rectifier. The DC link cap is always going to try and charge itself when its coupled to a rectifier and tranny, you can be a bit cleverer when your using switchmodes.

If an amp was drawing 32A constantly then at 90% efficency it would be sticking 3700W into a 4R load constantly. Ignoring the fact that no music has a duty cycle of 100% and that very little of it is a perfect sine wave anyway I think we're safe to proceed on the basis that no load is going to need full power, all the time.

Given that the music isn't constant and peak power is very rarely drawn for any great length of time; given a sufficent resevoir, fast enough SMPS and intelligent controller with PFC the average and peak current drawn from the supply can be significantly less than the peak current supplied to the load. Not to mention that you can soft start them much better than you can linear supplies. Granted given a constant high power load the input current is going to have to be higher, but the load profile of a sound system is quite different to that of a fan heater.

Another factor is that a controlled PSU drawing a fairly constant current is going to be much friendlier on the building supply than a linear whose demand is constantly going up and down. PFC also helps keep gennies happy and a well controlled DC link is going to minimise dv/dt stresses on the switching devices and prolong MTBF.

I know some of the transformer amps are still held in this god like awe, but isn't it time designers moved on from what is essentially 1970's technology? Are people going to be this resistant to Audio IGBT's too?


Edited by SteveAATW - 13 February 2008 at 2:05pm