Review and Measurements of Purifi 1ET400A Amplifier

[clanon]

Mosfet are on the bottom side of the board. The transformer is the output filter.

Why is there not A SINGLE picture of'em...?

 

[Rottmannash]

Why is there not A SINGLE picture of'em...?

they're shy and don't want the attention? There has to be a photo of the underside of one of those modules...

 

[mocenigo]

they're shy and don't want the attention? There has to be a photo of the underside of one of those modules...

You can see where one is here
https://vtvamplifier.com/wp-content/uploads/2020/04/DO01020121SMALL-1-scaled.jpg

And the other one here

https://www.audiosciencereview.com/forum/index.php?attachments/purifi-1et400a-red-box-jpg.29050/

 

[kiwifi]

they're shy and don't want the attention? There has to be a photo of the underside of one of those modules...

The FET's are sandwiched between the underside of the PCB and the metal base-plate (heat-sink), so the back of the module is just the base-plate. Even removing the base-plate would only show the back of the FET's, not the part numbers. If that is what you are after, you would need to de-solder them from the board.

 

[clanon]

The FET's are sandwiched between the underside of the PCB and the metal base-plate (heat-sink), so the back of the module is just the base-plate. Even removing the base-plate would only show the back of the FET's, not the part numbers. If that is what you are after, you would need to de-solder them from the board

 

[dped90]

https://www.whatsbestforum.com/threads/any-love-for-purifi.32530/

https://www.whathifi.com/reviews/march-audio-p452

https://www.soundstagehifi.com/index.php/opinion/1420-purifi-audios-pint-sized-powerhouses

However, not all Class D amps are offered as cheaply as many probably think.

https://www.stereophile.com/content/recommended-components-2021-edition-two-channel-power-amplifiers

But how these > $3K models might compare in actual listening tests with those audioscience.com and those above have reviewed would be very useful.

 

[spirosgon]

hi guys

i intend to buy this :

One moment, please...

for driving Martin Logan Theos , that in high frqs get very low, below 1 ohm

i understand that the amp will activate its protection circuit at such a low impedance and probably the match i'm thinking will be disastrous.

is this correct ?

 

[DTTOM37]

hi guys

i intend to buy this :

One moment, please...

for driving Martin Logan Theos , that in high frqs get very low, below 1 ohm

i understand that the amp will activate its protection circuit at such a low impedance and probably the match i'm thinking will be disastrous.

is this correct ?

afaik, especially for low impedance speaker, the 1ET904 should be the better choice

 

[Vincentponcet]

afaik, especially for low impedance speaker, the 1ET904 should be the better choice

Or ncx500

 

[Hayabusa]

hi guys

i intend to buy this :

One moment, please...

for driving Martin Logan Theos , that in high frqs get very low, below 1 ohm

i understand that the amp will activate its protection circuit at such a low impedance and probably the match i'm thinking will be disastrous.

is this correct ?

The current limit will kick in just clipping at too high voltages. So no big issues, it can do 28 amp if I remember right? So still 700 watts at 1 ohm or so

 

[Vincentponcet]

The current limit will kick in just clipping at too high voltages. So no big issues, it can do 28 amp if I remember right? So still 700 watts at 1 ohm or so

It provides 450W at 2 ohms with Astérix saying "Power is limited by overcurrent protection system (OCP)" and is not rated at 1ohm

 

[Hayabusa]

It provides 450W at 2 ohms with Astérix saying "Power is limited by overcurrent protection system (OCP)" and is not rated at 1ohm

I just looked at the datasheet and indeed it does not do a proper current clipping as I described.
Also 450 w at 2ohm is ~15amp RMS which would translate to 225 watt at 1 ohm.
My experience was with the Purify NC400 that I use with final electrostatics that also dip to 1ohm at 18Khz and that combination gives no issues current wise.
In the NC400 case I have soft-limited the input so the outputs would not exceed 27vRMS*

 

[Hayabusa]

I just looked at the datasheet and indeed it does not do a proper current clipping as I described.
Also 450 w at 2ohm is ~15amp RMS which would translate to 225 watt at 1 ohm.
My experience was with the Purify NC400 that I use with final electrostatics that also dip to 1ohm at 18Khz and that combination gives no issues current wise.
In the NC400 case I have soft-limited the input so the outputs would not exceed 27vRMS*

update from the datasheet:

This suggest the current clipping is behaving nicely at 1 ohm

 

[EdW]

hi guys

i intend to buy this :

One moment, please...

for driving Martin Logan Theos , that in high frqs get very low, below 1 ohm

i understand that the amp will activate its protection circuit at such a low impedance and probably the match i'm thinking will be disastrous.

is this correct ?

The impedance of most electrostatic speakers is only low at high frequencies - well beyond the point where there is significant audio power. I couldn’t immediately find an impedance curve for the ML Theos speaker but I expect it will have the typical unpleasant capacitive low Z at HF.
IET400 amps probably not likely to go into current limit since most of the audio power is in the bass/mid range. You could also look at the 7040 based amps if you want more current drive but a slightly lower price point than the 9040.

 

[David_M]

The impedance of most electrostatic speakers is only low at high frequencies - well beyond the point where there is significant audio power. I couldn’t immediately find an impedance curve for the ML Theos speaker but I expect it will have the typical unpleasant capacitive low Z at HF.
IET400 amps probably not likely to go into current limit since most of the audio power is in the bass/mid range. You could also look at the 7040 based amps if you want more current drive but a slightly lower price point than the 9040.

Exactly, music information at high frequencies is a such low levels (relative to midrange about -20 to -30db lower) and is very transient that it will never make the IET400 trip itself. I had Martin Logans' ESLs (Spires and Theos) with 0.5-ohm impedance at 20kHz. My Carver 7-Channel PA never broke a sweat with these speakers (and it was never rated at 1ohms)! Even my Carver's Red Cherry Tube Amps I had never broke a sweat either.

Remember that it's not just the impedance levels that matter but also the drive level. No music is recorded at 0dB at 15kHz or greater. That's just not the nature of music.

You have nothing to worry about.

 

[spirosgon]

Hi, brothers in HiFi-ism,

Getting down to the point :

I own the Martin Logan Theos :

https://www.martinlogan.com/en/product/theos

These speakers could go very low in high frequencies (copying from their manual ):

Impedance

4 Ohms, 0.8 at 20kHz. Compatible with 4, 6, or 8 Ohm rated amplifiers.

However, I would expect that there is not so much musical programm in these frequencies, and if there is, that would be for very limited time, that these freqs 'll be reached.

I'm in Greece and cannot get any locally available Purifi 1ET400A Amplifier, in order to test it /hear it with my speakers.

I fancy to buy, from France the following beauty :

AUDIOPHONICS LPA-S400ET Power Amplifier Class D Purifi 1ET400A 2x400W 4 Ohm - Audiophonics

We are proud to offer you the Audiophonics LPA-S400ET, a Class D stereo power amplifier based on two Purifi 1ET400A modules. This ready-built and ready-to-use version is for audiophiles who want to equip themselves with a foolproof amplification

www.audiophonics.fr

Could you, pls' advise whether this amp will face any issues, when programm will entail such high freqs ?

I would expect that it won't. But I don 't know whether any protection circuit of something will sneak in and shut the amp , etc.

Sorry for all this hassle and too many questions ! Hope, I don' t bother you a lot.

 

[Matias]

Hi, brothers in HiFi-ism,

Getting down to the point :

I own the Martin Logan Theos :

https://www.martinlogan.com/en/product/theos

These speakers could go very low in high frequencies (copying from their manual ):

Impedance

4 Ohms, 0.8 at 20kHz. Compatible with 4, 6, or 8 Ohm rated amplifiers.

However, I would expect that there is not so much musical programm in these frequencies, and if there is, that would be for very limited time, that these freqs 'll be reached.

I'm in Greece and cannot get any locally available Purifi 1ET400A Amplifier, in order to test it /hear it with my speakers.

I fancy to buy, from France the following beauty :

AUDIOPHONICS LPA-S400ET Power Amplifier Class D Purifi 1ET400A 2x400W 4 Ohm - Audiophonics

We are proud to offer you the Audiophonics LPA-S400ET, a Class D stereo power amplifier based on two Purifi 1ET400A modules. This ready-built and ready-to-use version is for audiophiles who want to equip themselves with a foolproof amplification

www.audiophonics.fr

Could you, pls' advise whether this amp will face any issues, when programm will entail such high freqs ?

I would expect that it won't. But I don 't know whether any protection circuit of something will sneak in and shut the amp , etc.

Sorry for all this hassle and too many questions ! Hope, I don' t bother you a lot.

Hi, you can order a 1ET400A based amp from some manufacturers in the EU: Apollon, boXem, Nord, Audiophonics. They all have days of trial and return policies that you can clarify with them before ordering your amp. But the amps should work fine with your speakers.