Purifi Class D: Junk?

Show us just one that’s not, and can almost double it’s rms measured wattage from 4ohm to 2ohm. The true indication of not current limiting, like many good A/B bjt amp.

George, seriously, you would do yourself well to educate yourself on how amps work, at a basic level.


Your metric seems to be "at full power". That is actually causing you to have confusion; its a misleading and lousy metric. What is important is that the amp behave as a voltage source, and by that I mean that it will make constant voltage regardless of the load impedance, at music power levels. If you exceed the power the amp makes into whatever impedance, it will clip (overload). I'm stating stuff that should be obvious but because you trot this trope so often, I have to assume that everything I'm telling you here is new for you.

With any amplifier the designer is faced with limitations; often verses cost. For example, our module has GaN output devices that are rated at 35 amps. This means that we should not exceed 17 amps in the field if we want the output section to survive; employing 50% margins is a good idea with any kind of semiconductor!


In addition the heatsink has to be effective, and yes you do need them for GaNFETs if you plan to run the amp at higher power levels, and especially if that involves lower impedances. So far all traditional solid state amps all have this factor in common too.

Finally you have to look at how much you want to spend on the power supply. Given you know the limitations of the output devices there's an argument for setting the power supply current to a certain maximum so that current will not be exceeded.


So really what this comes down to is what I've been harping to you all along: the current capacity of the output section, its heatsinks and the current available to support the output power of the amp are the variables and these are no different than traditional solid state.


What **is** different is that the output impedance of any class D amp employing GaNFETs is several times lower than any traditional solid state amp. That is why they can act as a voltage source to a much lower impedance than traditional amplifiers. So your metric of 2 ohms is not harder to attain than it is for traditional solid state should the designer feel its important. 

It must be getting close to the release of the your new Class-D to respond like that with such verve and virgor with doubling of wattage v halving of impedance loading.

Take it up with the likes of D’Agostino, Curl, ect ect manufacturers of the greatest amps that are recognized as being able to drive speakers with loadings that make Class-D’s run for the hills, they will tell you the same thing.

Like I said "if" all that matters is wattage with Class-D, and what you and your mate say is anywhere near true, then all anyone needs is this $300 3000w Class-D
https://www.bavasmusic.com.au/behringer-nx3000-power-amplifier-with-smartsense?gclid=EAIaIQobChMIqIa...

As much as I like my NC500 monoblocks on my easy to drive secondary speakers, they can’t compete in an A/B against my friends Gryphon Antillion on his Wilson Alexia MkII’s, and the Gryphon is less than half the wattage of the NC500’s

As I said, the latest $16K Curl amp does not double nor is it state of the art.....it is very good.....but no $60K Gryphon or $110K Boulder. Jay listened to the JC1+s briefly and then they went on their way.....not competitive.

Of course quality matters. Behringer amps are just so so sonically. Nothing like a tweaked IceEdge or tweaked Purifi. Every single thing you do matters. Power output is only one of an infinite number of things that change sound.

A stock Hypex module (less than $150 each wholesale) plus linear power supply versus a $40K Gryphon. I hope the Gryphon would be better. As I said, the power output is only one factor in how something sounds. I made the IceEdge module sound way more dynamic sounding with my mods.....but there was no increase of current of voltage. Nothing is that simple.

I hope not one is claiming that a tweaked IceEdge or tweaked Purifi is state of the art.  Tweaked IceEdge was $2K....tweaked Purifi is $2.6K.  There will be and maybe there is better class D......and it will just keep getting better and better.  Those who have more money.....please read the reviews of the AGD GaN amps and the Merrill Class D GaN amps.....they are getting rave reviews.....and they start at $7500.  Can you afford that?......most cannot.  I bet the average money spent on a high end audiophile system is under $20 grand for everything.  All this talk about super expensive gear here is really out of place.  Remember, for less than $1000 delivered VTV stereo amp with the Purifi amp modules and the Purifi buffer board is yours......the same basic proto amp from Purifi was A/Bed with $40K Constellation amps and found to be as good.  The revolution has begun!

Nothing like a tweaked IceEdge or tweaked Purifi.

Save use all, looks like another one bringing out his new "tweaked" Class-D, probably has an orange fuse in it too

Can anyone save us us against boutique Class-D manufacturers using threads to promote their own yet to be released stuff onto the market.

BTW Those $300 3000w Behringers are ICE POWERED modules!!!!

Two problems Class-D have still.
The switching frequency, which is fixable with GaN technology the way only Technics so far have used it.
And the second, is current delivery, where wattage goes up almost doubling for each halving of impedance down to 2ohms or even less.

Take it up with the likes of D’Agostino, Curl, ect ect manufacturers of the greatest amps that are recognized as being able to drive speakers with loadings that make Class-D’s run for the hills, they will tell you the same thing.

Actually they won't. They will all tell you the same thing- the limit of any solid state amp, class D or no, will be current the output section can withstand, the ability of the heatsinks to adequately cool the devices and how much current is available from the power supply.

I will note one thing though- I've seen a number of SMPSs (Switch Mode Power Supplies) used in class D amps. I think its a bad practice. They work, sort of; the problem is that class D amps go from almost no current draw at idle to quite a lot at full power. SMPSs don't have a lot of capacitance at their output and so can be drained faster than they can replenish. A lot of them will shut down if you put a lot of capacitance at their output. So if you're not running an amp with a regular power transformer and a lot of capacitance available for the class D amp to feed on, you're probably not hearing what it can do.