Purifi Based Amps - Any Opinions?

Hello all,

I've been trying to gather information and spur conversation regarding these class D amp modules over on the AVS forum as well as the Magnepan user group with virtually no interest. I know they're fairly new to the market so first hand experience is probably slim at this point. I thought I'd reach out here also.

I'm going to be diving back into some Magnepan speakers in the near future and I'm considering an amplifier based on these modules or a Hegel class AB amp. 

The distortion and wattage specs are really really good on the Purifi modules but I have some concern about the output current capability. Maggie's are known to like high current to sound their best and these modules max out at 25 amps per channel. 

Any thoughts and opinions will be appreciated.


I've heard nothing but good reviews about the Purifi modules. There is a guy that takes them one step beyond too. Changes a few things like fuses, wiring, solders direct, very few plugs... Suppose to be the Cats Meow.. 

The guy you’re thinking of is Ric Schultz, Tweak Audio.

I have his EVS 1200, which is based on IcePower 1200AS modules. It’s amazing. Others have commented on non modified 1200AS modules tossed into a chassis and found them not so great

He has a page up on his site you might consider to review
I think it will depend on the Maggies in question. I drive .7s with an amp that's specified as having a max drive of 18 amps/ch. It's plenty of power for most music in a large room. 

The real concern is whether these Purifi amps can remain linear into low impedance speakers, a problem for many class D designs IME. What happens is you end up with no bottom octave bass. I'm not an EE so cannot say why this occurs, but I suspect the measurements performed on such amps fail to mimic real-world speaker loads in some cases. 

With most class AB amps, I have a good track record of predicting their success in driving these loads. The only potential issue that would concern me with Hegel is whether the specific amp has adequate cooling ability. Stereophile judged one of their amps as having "inadequate" heat-sinking for prolonged use. 

I've successfully used the Parasound Halo integrated to drive Maggies. An amp like the A21 is a safe bet. 

I’ve used numerous good quality class AB and class D amps on Magnepans and have noticed a difference to the bass reproduced between the two but have not read much from others on these differences that I clearly perceive. IOW, it could be just me.
I’ve achieved good results with both but perceive the bass from the class D amps I’ve used as being more solid, powerful and dynamic. In fact, I distinctly recall thinking the bass reproduced through my first class D amp, a Class D Audio SDS-440-CS stereo unit, was noticeably the best bass I’d ever heard my Magnepan 2.7QR speakers produce since I owned them.
After careful comparison and contemplation, however, I came to the conclusion that the bass was a bit exaggerated with the class D and seemed to truncate the decay times on bass notes, most likely due to its Damping Factor being rated at a few thousand as opposed to my class AB amps being rated at a few hundred.
I currently believe this ultra high damping factor on both channels resulted in firmer control of the starting and stopping of the rather large 623 sq. in. planar-magnetic bass sections on each of the 2.7QRs, which tended to exaggerate the leading edges of the bass notes and truncate the decay times.
While I admittedly enjoyed this overall bass overemphasis on my system in general, I ultimately realized it wasn’t as accurate or natural as I convinced myself I should strive for. So I purchased an Audio Kinesis Swarm 4-sub distributed bass array (DBA) system powered by a 1K watt class AB amp/control unit. In combination with my then 2.7QR and current 3.7i Magnepans, I’ve perceived these systems bass performance as being more accurately and naturally powerful and dynamic while also providing more accurate and natural decay times.
While I don’t know for certain and have no experience with any Purifi amps yet, I believe class D amps in general share these very high damping factors and, therefore, the bass qualities I described. Ymmv, of course, but I thought my experiences may be of some use to you since you’re likely to have similar perceptions of the bass performance differences as I do. I also tend to doubt you’ll be able to perceive any significant bass performance differences based on amperage capacity and current delivery.


I'm not sure what your budget is but if you want to stay with a main stream company the NAD M33 is a purifi based amp. Others that offer good performance are Nord, Apollon and March. IMO you should avoid modifictions that are suspect at best and void warranties at worst.  
That iron grip on the panel is exactly why I'm interested in the Hegel and Purify. 

As far as which maggie I'll end up with is still up in the air. It could be anything from the LRS to the 1.7i. I'll definitely start out without subs and evaluate from there. I owned MC1s and then 1.6s for about eight years. I loved my 1.6s but always felt I left some of their potential on the table due to my electronics. I'm wanting to obtain a great  synergy between head end and the maggies this time around.

I would absolutely love to have that M33 but it's really out of my budget. I'm leaning more towards a Purifi Nord and a streamer/DAC. Maybe $2500 thereabouts for the combo. Then maggie's on top of that.
VTV Amplifiers has both the Purifi and Hypex amps available at very attractive prices, and it is assembled in and shipped from the U.S. They are sold on-line only AFAIK. I've ordered a Hypex amp from them which should arrive later this week. I'll let you know what I think of it after it gets here.
joemags:" That iron grip on the panel is exactly why I'm interested in the Hegel and Purify."

     That's my point, Joe.  The sound of the bass on any Magnepan is going to sound different depending on whether you power them with a class AB or a class D amp.  Even the type of amps used to power any subs used will influence the overall system sound.  

My  Hypex NCore NC252MP from VTV arrived last week and I've been enjoying it immensely. It is a well-built, good-looking amp and I have been very satisfied with its sound. 

As noted above, they also have versions available with the Purifi and Pascal modules besides the Hypex version I bought. If you are in the US and don't want to purchase from overseas, it is worth checking out VTV. 
It's a wonder why REL
 uses class AB for their subs when Class D produces the superior bass... 

REL uses a Class AB in their G1 MKII and some of their other subs, but Class D in their No. 25, 212/SE, S/812, Carbon Limited, and S/510.