Eva said:
As normally defined, a true resonant SMPS has an LC tank with significant energy storage from one cycle to the next, which normally means having a high-current low-loss resonating capacitor (usually ceramic or polypropylene) and a high-AC-current low-loss resonating inductor (usually wound with Litz wire) to store enough energy and still keep the losses down.
Using inductor current (small inductor eg. printed) to charge and discharge parasitic capacitance on each edge is normally termed quasi-resonant or resonant-transition because there's no cycle-to-cycle energy storage -- also referred to as ZVS/ZCS depending on how the switching loss is reduced.
Most of the amps quoted by workhorse seem to be quasi-resonant ZCS/ZVS by this definition, with the possible exception of the Crown (and PKN).
But as Eva said, all of them can be said to be resonant in one sense, and different people have different definitions.
(yes I understand about all the different types of SMPS, we probably don't want to go there on this forum
If you want the highest possible power density and output power then a resonant supply has the edge if you run it at a high enough frequency (MHz?); this isn't usually the case in class-D SMPS, so I'm curious about what PKN do and why.
Of course Peter doesn't have to tell us, but I suspect giving some information away is fairly safe given the increased difficulty of making a reliable resonant supply -- it's not something that can be copied easily except by someone who really knows what they're doing, and if they know this much they could design their own...
Ian
fb said:Iand, did you ever investigate these amps any more?
There was more discussion on the speakerplans forum here
http://www.speakerplans.com/forum/a-decent-lightweight-amp-at-last_topic24766_page6.html
but nothing further since March -- though we did find out that the PKN uses an LLC resonant SMPS, not a quasi-resonant one.
Personally I'm now waiting to try out a Peavey IPR 6000, due here in a couple of months -- don't know what they'll cost in the UK but street price in the USA is said to be around $600 for 2x2000/4 or 2x3000/2...
fb said:Thanks for that, guess I'll have to wait for some reviews on those too
I expect real detailed reviews will appear soon in the trade press -- Peavey's announcement of the IPR amps has raised a lot of interest in the pro sound world, unlike PKN they're a well-known PA manufacturer (thought maybe not with absolutely the highest reputation) who will be aiming to sell a lot of them.
If they deliver what they promise then these could blow a big hole in the high-price high-power class-D amplifier market -- because I know what these really cost to build (especially in China), and this bears no resemblance to the current market prices.
Prices are high now because people are willing to pay them -- and of course companies have to recoup the R&D cost needed to develop the amps, which is obviously way higher than a linear amplifier. So all high-power class-D amplifiers are expensive, nobody in the market right now wants to drop the prices and see their revenues plummet.
Peavey are effectively breaking this cartel by entering the market with pricing much closer to production cost (with a decent margin, of course) in the hope that they'll sell far more amplifiers on the back of this -- the volumes in the sub-$1000 market are much higher than in the $2000+ market which is where most similar amps are right now.
$600 "street price" -- which probably means lower from the cheapest suppliers -- for a 2x2000/4 2x3000/2 amp with inbuilt crossovers is *really* going to put the cat among the pigeons unless it's total rubbish -- OK maybe it won't sustain this power into 2 ohms, so use it into 4 ohms and still get 4kW for very little money...
fb said:Still waiting on the Peavey IPRs....
Meanwhile - I noticed PKN now offer an even larger amp - XD-6000, 2x3650W@4ohm
And with 7.9kw draw from the mains (sustainable over a minute or so if it's the same as the XD-4000) you'd better have a decent feed...
(1250 euros isn't so bad either
fb said:By the way, you might also be interested to know that Red Rocks are planning to release a 4kw SMPS + 2kw amp modules after their holidays in September
Is that 2kW/4ohms?
If so I'm very interested, they'll be the first people (apart from CAD Audio who nobody will touch with a bargepole) and Hypex (who are expensive and only want to sell their big amps to OEMs) to sell modules to the DIY market at these power levels.
Do you have any clues about prices?
Ian
It is 2kW/4ohms...
I found out incidentally - I was asking what modules they had planned as they have licensed their D600 to an OEM (I was planning to use that module).
Send them an email, I'm sure they'll let you know - I'm curious too, just assuming it will be out of my budget for the time being.
I found out incidentally - I was asking what modules they had planned as they have licensed their D600 to an OEM (I was planning to use that module).
Send them an email, I'm sure they'll let you know - I'm curious too, just assuming it will be out of my budget for the time being.
you can only use a high power amp amps properly if they have PFC on board.
That's why I opted for the XE-4000. the pfc stage also helps to flatten out AC mains variations, long extension cords et.
a non PFC amp of 4kW would draw peak currents close to 100A at 220V, (by that time the 220 is not 220 anymore.
That's why I opted for the XE-4000. the pfc stage also helps to flatten out AC mains variations, long extension cords et.
a non PFC amp of 4kW would draw peak currents close to 100A at 220V, (by that time the 220 is not 220 anymore.
Found myself
PFC inductor is splitted into two (serial?) inductors here...
Those are the resonating inductors in the LLC PWM stage, the PFC inductor is the single one to the right.
Ian
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