Bruno Strikes Again. Purifi 1ET7040SA VTV Amplifier.

[Stephen Bayley]

 

[Stephen Bayley]

Securely packaged with power cord in packet

 

[Stephen Bayley]

Noticeably larger than the P451 mono block to accommodate the larger 7040SE board and the new switching power supply that March Audio is using. Finish is perfect with not a mark anywhere.

Looks like I have SNo 15 of the P501 with a despatch date on 1 May 2022.

Unfortunately I won't be able to install these till Sunday. A combination of obligations and some travel over the next few days. I also have to reterminate my speakers cables from locking banana to spades as the extra depth of the P501 makes the cabinet space too tight.

 

[Stephen Bayley]

I have the P501's installed a day early. First here is the P451 against the larger P501 to show the size increase.

Prior to the swap I listened to one of my reference tracks to try to capture the original sound, with my wife who has very keen ears. Reference track is Patricia Barber - Clique 352/24; the track is The In Crowd.
I always play this track LOUD due to its overall clarity and simple bass/piano/vocal composition. For those who don't know it, it has a driving deep bass track with sharp cracks from the bass strings hitting the fret board hard on some notes, and some heavy and sharp hitting of the piano upper notes in places.
Perhaps first the rest of my system, quite boring for ASR folk: Topping D90SE, Pre90 and B&W 702S2; so quite revealing.

With the reference track played twice the swap was made. About an hour as I re-terminated the speaker cables (van den hul 192 strand silver plated).

With the system updated and warmed for 10min we listened again, same volume (-18 with DAC at 5.2v out) and same positions.

Both opinions were very similar, the heavy sharp piano hits were more dynamic; the heavy bass notes clearer and the loudest bass string hit against the fret board made me jump, it was that dynamic and sharp (haven't jumped before at this point in the song).

It's early days but it looks like a winner to me and for those special tracks like the reference it is a worthwhile change from my perspective.

Overall clarity is the same as one would expect, the difference would only be noticeable when driven loud, which I do a lot off. More later as I work my way through more of my music.

I understand the difficulty of trying to compare listening sessions an hour apart, however I have had this system in that configuration for a year, and play this song at least 5 times a week, I really like it. You have my (and my wifes) honest and considered opinion. I'm sticking with this new configuration. Currently having a wine while I enjoying the new toys! Cheers.

 

[pogo]

Could perhaps also be due to the other power supply and less to the purify.

 

[Stephen Bayley]

Could perhaps also be due to the other power supply and less to the purify.

I agree with you on that. What caught my curiosity after seeing this thread, then visiting March Audio to see what they were doing in this front, was their description of their new switching power supply. In their words: output is not dependent on mains input voltage variation (so you always get the expected output from the amp) and larger output capacitence to lower 'buss pulsing' on transients.

Just listened to:
Deep Purple - Machine Head, especially Smoke on the Water, 2011 Japanese remaster in DSD64, and
INXS - The Swing, 2013 remaster in 192/24.
I play both a lot, and loud, and in both instances the bass track is more authorative and there is now no (or less) compression on crescendo everywhere, I didn't know I had compression until this change.
I do think the power supply is firmer, there may be some dynamic improvement in the 7040, can't tell from my seat where it's coming from, just know it's coming from somewhere other than my imagination!

 

[kchap]

I agree with you on that. What caught my curiosity after seeing this thread, then visiting March Audio to see what they were doing in this front, was their description of their new switching power supply. In their words: output is not dependent on mains input voltage variation (so you always get the expected output from the amp) and larger output capacitence to lower 'buss pulsing' on transients.

Just listened to:
Deep Purple - Machine Head, especially Smoke on the Water, 2011 Japanese remaster in DSD64, and
INXS - The Swing, 2013 remaster in 192/24.
I play both a lot, and loud, and in both instances the bass track is more authorative and there is now no (or less) compression on crescendo everywhere, I didn't know I had compression until this change.
I do think the power supply is firmer, there may be some dynamic improvement in the 7040, can't tell from my seat where it's coming from, just know it's coming from somewhere other than my imagination!

Have you peeked inside? I would be interested to know if the PSU is a customised Hypex or are they using another supplier.

To keep inventory and manufacturing costs down I would not be surprised if March Audio is using the same PSU in the P421. The P421 is wider the the original P451; I think uses the same case as the P501. It would make sense to to use the same PSU.

 

[EdW]

Have you peeked inside? I would be interested to know if the PSU is a customised Hypex or are they using another supplier.

To keep inventory and manufacturing costs down I would not be surprised if March Audio is using the same PSU in the P421. The P421 is wider the the original P451; I think uses the same case as the P501. It would make sense to to use the same PSU.

Probably quite different than the Hypex SMPS1200A400 since the amplifier has a universal 100-240V rating without any switches or jumpers. Suggests that the power supply is stabilised against input voltage variation and therefore might also be stabilised against load variation. The Hypex SMPS are not perhaps built to the same standard as the Purifi modules so it would be interesting to see a teardown or even just some nice photos on the March Audio webpage. March audio quality appears to be very good and if they have beaten the competition here then that is a further reason to consider them for quality builds of Purifi amplifiers.

 

[Kachda]

Does March still use those touch sensitive piezo electric switches ? I don't like them, they are so finicky.

 

[cochlea]

Have you peeked inside? I would be interested to know if the PSU is a customised Hypex or are they

Have you peeked inside? I would be interested to know if the PSU is a customised Hypex or are they using another supplier.

To keep inventory and manufacturing costs down I would not be surprised if March Audio is using the same PSU in the P421. The P421 is wider the the original P451; I think uses the same case as the P501. It would make sense to to use the same PSU.

According to their website: “The new main power supply is custom designed and a significant improvement over the Hypex unit previously used. It has very low noise with high current output and excellent voltage regulation. Efficiency is improved with power factor correction.”

So it’s not really clear. My new P262 is supposed to be here tomorrow (Monday.) I’ll take a look. Can’t wait!

Edit: Not sure why the double quote.

 

[Stephen Bayley]

I haven't had a peek inside, thought I would leave it to a reviewer.
I can confirm the new touch power switches work great. I was annoyed with the old P451 solution and resorted to using a simple trigger set up (9v battery in a plastic box with a switch) which worked fine.

Having played the system for three days I am sure the new power supply has a big input to the transient improvement I'm hearing. Hope my posts from day 1 weren't too over the top, I was excited with what I heard.

From what I understand the new power supply is now standard across the range.

 

[Matias]

Possibly the SMPS from @MicroAudio .

SMPS for Audio Applications

Hello I am starting this thread into this nice place with many nice people to discuss my SMPS products. There are 7 models coming up 3 of them will remain parked and will be released on time only. I had to work so hard to bring up those SMPS to reality after countless hours of design and...

www.audiosciencereview.com

 

[kchap]

I haven't had a peek inside, thought I would leave it to a reviewer who doesn't have the worry about warranty or scratches.
I can confirm the new touch power switches work great. I was annoyed with the old P451 solution and resorted to using a simple trigger set up (9v battery in a plastic box with a switch) which worked fine.

Having played the system for three days I am sure the new power supply has a big input to the transient improvement I'm hearing. Hope my posts from day 1 weren't too over the top, I was excited with what I heard.

From what I understand the new power supply is now standard across the range.

Yes, I suspected that the PSU was the same. Well, at least in the P421 and P501.

I use an Emotiva 12V Trigger to operate my P451s. The Trigger Input is connected to a spare USB port on the RPi 4B using USB to 3.5mm TS cable. As I said in in another thread, it was expensive and the LEDs are too bright but it works and looks neater that anything I could build.

 

[SCG]

Since there seem to be some confusion around the power of these new modules, lets clarify a few things:
1. the 1ET400A power is limited by power supply rails voltage for loads above 3.3 Ohm.
2. the 1ET400A power is limited by its self-protection for loads below 3.3 Ohm.
3. the 1ET7040SA power is limited by power supply rails voltage for loads slightly above 2 Ohm.
4. the 1ET7040SApower is limited by its self-protection for loads below slightly above 2 Ohm.

This means that with an identical power supply, both 1ET400A and 1ET7040SA deliver the exact same power for loads above 3.3 Ohm
Any OEM using an Hypex power supply and selling more than 210W in 8 Ohm for either 1ET400A or 1ET7040SA is misleading at best.

Compared to the 1ET400A, the interest of these new modules is their ability to deliver huge amounts of current in very difficult loads. For more "normal" speakers, no notable difference.

Thanks, I really appreciate the type of posting you do, very informative, direct, and helpful! I read about the new 1ET7040SA but couldn't find any good info on real-world differences between it and the 1ET400A in stereo applications at 4 ohms and above (even today in May '22) and your post from Jan of this year makes it abundantly clear!! Thanks again, I wish you were a US supplier as I would have purchased from you.

Anyhow that doesn't change anything to my initial statement: the 1ET7040SA will deliver the exact same power as the 1ET400A above 3.3V when powered by the same PSU.

Small typo from post #50 of this thread but I believe you are referring to it being the same above 3.3Ω (ohms vs volts) when using the same PSU.

 

[Stephen Bayley]

I have an interesting comparison of the two Purifi cards side-by-side. The 7040SA is noticeably larger and it also has 6 power supply capacitors per rail rather than the 400A's 4 capacitors, so a lift in the on-board current reservoir, which coupled with the March Audio claimed increase in power supply filter capacitance, may be the origin of the improved transient performance I am experiencing.

I also have a higher res image of the new March Audio power supply partial view found on their website, the PCB is branded with the March Audio logo, so it doesn't seem to be an off the shelf purchase but rather a special build.

Both images came from Alan March while I was discussing ordering of the P501's.

 

[KMO]

I've been wondering for ages, and never seen it mentioned, so I'm going to ask, despite it not being very important.

What's the riser board on the amp? Why separate stuff out? Just lack of physical space?

As I type this, it occurs to me that it might be a microcontroller. Is it?

 

[boXem]

I've been wondering for ages, and never seen it mentioned, so I'm going to ask, despite it not being very important.

What's the riser board on the amp? Why separate stuff out? Just lack of physical space?

As I type this, it occurs to me that it might be a microcontroller. Is it?

It is the control board, modulator on one side, microcontroler on the other side.
The main board is the power stage, single sided.
I believe that the idea is to have a standard small control board while differentiating the power levels with the main board.

 

[SCG]

Having the supply rails specified with absolute max voltage +/- 75 V DC like the 1ET7040SA allows to be excluded from the EU Low Voltage Directive scope with all the advantages associated.

Being in the US not familiar with the EU Low Voltage Directive, so gave it read over but wasn't obvious what "all the advantages associated with being excluded" were. If your supposition is correct, can you briefly outline what those advantages are?

 

[boXem]

Being in the US not familiar with the EU Low Voltage Directive, so gave it read over but wasn't obvious what "all the advantages associated with being excluded" were. If your supposition is correct, can you briefly outline what those advantages are?

EU LVD is a set of safety regulations. If a product is concerned, it represents non negligible additional costs for demonstrating the compliance to these rules. This is a reason why most affordable products that need mains supply use an external generic power supply. The cost associated to LVD is shared between all the power supply users while the product itself is not concerned.

 

[ethanhallbeyer]

After going through this thread, I have a couple of questions:

1. Does the higher current and possibly damping factor only benefit certain speakers and not all speakers? From what little I've read on it, damping factor helps with the amp's "grip" on the speakers, to better control the drivers. And as for current, certain speakers like Maggies seem to thrive on higher current amps, right? But would there be a general, across the board benefit for all speakers? Trying to determine if the differences between the original and new, more powerful Purifi would be worth the move to the newer modules. I have a pair of original purifi module based monoblocks. From what boXem | audio posted earlier, it would seem that only after going lower than 3ohms would there be a benefit.

@Stephen Bayley & others:
2. For those who have the March P501 or P421 (formerly P451 monoblocks, what is the difference you notice with the front power switch vs the original used on P451? It's supposedly not as finicky on the P501/P421?