Review and Measurements of Purifi 1ET400A Amplifier

[restorer-john]

I'll let the experts help you with this. But the only time I hear a slight pop (it's more like a gentle crackle) is when I switch on amp directly from the power point.

I bought an rf remote controlled powerpoint to switch on/off the amp, but looks like the rf is interfering with amp. With the rf powerpoint on I hear crackling (as if I'm listening to an old vinyl) during the music. So I have taken it off and now leave the amp on all the time

An amplifier should be silent (electrically) when switched on and off, either directly at the power point or via a standby/soft power switching arrangement.

The fact that quite a number of people are making complaints in various threads about switch on/off noises, crackles and pops suggests to me deficiences in transient noise amelioration in some of these products.

 

[1lifeliveit]

An amplifier should be silent (electrically) when switched on and off, either directly at the power point or via a standby/soft power switching arrangement.

The fact that quite a number of people are making complaints in various threads about switch on/off noises, crackles and pops suggests to me deficiences in transient noise amelioration in some of these products.

Hi John,
Can I pick your brain on this RF interference with the amp? I've had these RF remote powerpoints (just your standard ones from bunnings) on my home theater setup with 3 amps and haven't had any issues with pops/crackles. But they are all Class A/B with linear power supplies.

Now that I have issues with the VTV eval amp, is it the SMPS or the amp board itself gets affected by RF interference?

The only difference between the home theater set up and the lounge music system (where the VTV is) is that the RF powerpoint was very close to the amp (less than half a meter). There's no way to move the amp away from the powerpoint as the bookshelf it sits on, backs on to the wall with the powerpoint.

 

[restorer-john]

Hi John,
Can I pick your brain on this RF interference with the amp? I've had these RF remote powerpoints (just your standard ones from bunnings) on my home theater setup with 3 amps and haven't had any issues with pops/crackles. But they are all Class A/B with linear power supplies.

Now that I have issues with the VTV eval amp, is it the SMPS or the amp board itself gets affected by RF interference?

The only difference between the home theater set up and the lounge music system (where the VTV is) is that the RF powerpoint was very close to the amp (less than half a meter). There's no way to move the amp away from the powerpoint as the bookshelf it sits on, backs on to the wall with the powerpoint.

Which RF units are they? The Arlec 4ch ones?

Do they contain a 10A DPDT 250V relay that switches both the active and the neutral or do they have an internal solid stage relay? Some just use an SPDT relay and I have come accross some that switch the neutral not the active- actually dangerous. Some others contain an SMPS of their own, but most just have a series cap, resistor and rectifier to run the RF circuitry. They themselves can be noisy.

The RF unit only recieves of course, so it shouldn't make any difference where it is, as long as its own internal PSU is quiet.

The amp itself may have no RF front end suppression filtering either.

 

[1lifeliveit]

Which RF units are they? The Arlec 4ch ones?

Do they contain a 10A DPDT 250V relay that switches both the active and the neutral or do they have an internal solid stage relay? Some just use an SPDT relay and I have come accross some that switch the neutral not the active- actually dangerous. Some others contain an SMPS of their own, but most just have a series cap, resistor and rectifier to run the RF circuitry. They themselves can be noisy.

The RF unit only recieves of course, so it shouldn't make any difference where it is, as long as its own internal PSU is quiet.

The amp itself may have no RF front end suppression filtering either.

Yes the Arlec ones (model RC212). I'm not very electrically savvy and I have no idea what they contain.

Regardless, they ARE noisy. So I'm going to leave the amp on all the time. I read conflicting info regarding leaving these on. I'm sure the amp will be fine, albeit leaving it on reduces life? OR switching them on/off regularly is not good for the capacitors and they age quicker ?

 

[jdhiro]

I just saw your message, I was looking to buy that one, did you get it yet? Is it good? Happy with your purchase?

I've waited almost 2 months for my Apollon amp, but it has not arrived. Apollon has promised me several times that "It'll just be a couple more days in customs, you'll have it this week!" None of it has been true. I'm out of patience. I've never had a package "sit in customs" for a month. If I don't see movement on it by the end of the week I'm going to be cancelling the order.

 

[jdhiro]

Received the "mini" last Friday. I haven't been able to fully assess it yet, but the sound is very promising indeed. It's powerful and lively with great bass and delicate treble. I'm not sure why it took so long to arrive, but it seemed to have been in its shipping packaging for quite some time, since the black plastic wrapping used sadly left marks on the high gloss surface of the amp, almost like a chemical reaction. I guess I have to try to polish it out..

Would love to hear your review, and your luck in getting those marks out of the finish...

 

[ezra_s]

I've waited almost 2 months for my Apollon amp, but it has not arrived. Apollon has promised me several times that "It'll just be a couple more days in customs, you'll have it this week!" None of it has been true. I'm out of patience. I've never had a package "sit in customs" for a month. If I don't see movement on it by the end of the week I'm going to be cancelling the order.

Thanks for the report, I turned my eyes on the boxem 4215 with orange front (altough it seems to not being shipped until the end of august ordering now), looking sexy and to my non-expert eyes they look to have a nicer cable management than audiophonics equivalent with those cables all around the place and touching the heatsink.

 

[mocenigo]

Thanks for the report, I turned my eyes on the boxem 4215 with orange front (altough it seems to not being shipped until the end of august ordering now), looking sexy and to my non-expert eyes they look to have a nicer cable management than audiophonics equivalent with those cables all around the place and touching the heatsink.

This is not a compliment. It is not difficult to have a better cable routing than audiophonics. Boxem however seems to deserve kudos for his work on design, cable routing (indeed), build quality and also the use of a SW controlled board (which allows bridging).

 

[mocenigo]

I've waited almost 2 months for my Apollon amp, but it has not arrived. Apollon has promised me several times that "It'll just be a couple more days in customs, you'll have it this week!" None of it has been true. I'm out of patience. I've never had a package "sit in customs" for a month. If I don't see movement on it by the end of the week I'm going to be cancelling the order.

Where do you live? Sometimes customs are really nasty, and there is *nothing* the shipper can do. It is actually all on your side – have you received a letter from customs?

 

[jdhiro]

Where do you live? Sometimes customs are really nasty, and there is *nothing* the shipper can do. It is actually all on your side – have you received a letter from customs?

I'm in the USA -- Seattle, Washington specifically. The good news is that as of this morning UPS has custody of the package, and I have a delivery estimate for Friday.

I really don't think this is anything on my side. The package is still in Slovenia, and UPS didn't have their hands on it until today.

 

[jdhiro]

This is not a compliment. It is not difficult to have a better cable routing than audiophonics. Boxem however seems to deserve kudos for his work on design, cable routing (indeed), build quality and also the use of a SW controlled board (which allows bridging).

Wait, they are bridging a Purifi? I don't see that mentioned anywhere on their website.

 

[boXem]

Wait, they are bridging a Purifi? I don't see that mentioned anywhere on their website.

Yes we do. Through an external cable. Website communication sure needs an update.

 

[jdhiro]

Yes we do. Through an external cable. Website communication sure needs an update.

Thanks! Where can I get more information on this? What kind of power ratings can be expected in bridged mode?

Purifi has said their modules aren't designed to be bridged - what makes it OK in this application?

Have these questions all been asked somewhere else where I can find them?

 

[JohnYang1997]

Thanks! Where can I get more information on this? What kind of power ratings can be expected in bridged mode?

Purifi has said their modules aren't designed to be bridged - what makes it OK in this application?

Have these questions all been asked somewhere else where I can find them?

It's not designed for bridge operation because it's designed as single ended with remote ground sensing. They will not guarantee the performance in bridge operation.
It should work fine. But you get a bit less performance. When you connect to 4ohm load, performance is similar to 2 ohm also with higher noise because of bridge operation.

 

[mocenigo]

I'm in the USA -- Seattle, Washington specifically. The good news is that as of this morning UPS has custody of the package, and I have a delivery estimate for Friday.

I really don't think this is anything on my side. The package is still in Slovenia, and UPS didn't have their hands on it until today.

Then I am sorry for you. I thought the package was indeed in transit and actually blocked st customs. Seems it is now moving, however. Apollon has excellent build quality and I am sure you will enjoy your amp. They were probably swamped by backlog.

 

[mocenigo]

Wait, they are bridging a Purifi? I don't see that mentioned anywhere on their website.

technically, they are bridging two Purifis (and now I duck under the table hoping nobody sees where I am)

 

[boXem]

Thanks! Where can I get more information on this? What kind of power ratings can be expected in bridged mode?

Purifi has said their modules aren't designed to be bridged - what makes it OK in this application?

Have these questions all been asked somewhere else where I can find them?

I am not communicating too much on the subject because I never had the opportunity to take a batch of amps, measure them and do some stats on the results to provide data I feel I can trust. Let say that the few ones I measured where clipping above 800 W in 8 Ohm.

The main issue with bridging is diagnostics. Some faults need the power stage to be shut down to avoid catastrophic consequences. In bridged hardware mode this shutdown won't happen because one half of the stage has no idea of the existence of the other half. Just a few lines of code is software mode and the system is safe.

It's not designed for bridge operation because it's designed as single ended with remote ground sensing. They will not guarantee the performance in bridge operation.
It should work fine. But you get a bit less performance. When you connect to 4ohm load, performance is similar to 2 ohm also with higher noise because of bridge operation.

As long as the ground sensing is not left floating it's not such an issue. As written above, main issue is indeed the risk of not reacting properly when things go crazy.
You can add to the list of inconvenients higher idling losses. And to the list of advantages sh@tloads of power

 

[Eidie]

I’ve had the March P451 monoblocks for a couple of weeks. Paired with an RME ADI-2 DAC. The noise floor is way below audible. As far as I can tell they are honest to the source. Easily the best amps I’ve ever heard.

https://www.audiosciencereview.com/forum/index.php?threads/why-arent-there-female-audiophiles.23325/

There are.

 

[jdhiro]

And to the list of advantages sh@tloads of power

This is my primary motivator. I'm concerned that the standard 1ET400A doesn't quite provide enough juice to drive my B&W 804s to their full potential at high volumes.

 

[Matias]

This is my primary motivator. I'm concerned that the standard 1ET400A doesn't quite provide enough juice to drive my B&W 804s to their full potential at high volumes.

Purifi is working on high power modules, although no specs, release date and price has been released.