Bruno Strikes Again. Purifi 1ET7040SA VTV Amplifier.

[soerenssen]

The 1ET7040SA delivers more power in very difficult loads. Amps with the 1ET7040SA are more expensive because the module is more expensive. Plain and simple.
What means "beefier PSU"? That is unrelated to the amp modules.

I meant more power reserve, especially in a dual mono configuration.

 

[goryu]

I think I am about to scream....

 

[mk1classic]

What do you want to do with your speakers?
At what listening level do you expect the speakers to deliver? Low level listening in small apartment building or have a party in an open field?

An example. Each speaker has a sensitivity of approx 86db/m per watt .
250W per channel will give you a gain of approx 24db per channel. i.e. you can play max 100 db at 1m with one speaker.
Two speaker playing the same sound will give a another gain of+3db. i.e. max 103 db at one meter listening distance. If your 2m away you listen at 97db, at 3m away 94db

If you go for a 500W per channel amp you only add 3db per speaker (gain of approx 27db). The problem is that your speaker drivers don't like to play 103db at 1meter.

 

[soerenssen]

I think I am about to scream....

 

[boXem]

I think I am about to scream....

I get it now. Sorry

 

[soerenssen]

What do you want to do with your speakers?
At what listening level do you expect the speakers to deliver? Low level listening in small apartment building or have a party in an open field?

An example. Each speaker has a sensitivity of approx 86db/m per watt .
250W per channel will give you a gain of approx 24db per channel. i.e. you can play max 100 db at 1m with one speaker.
Two speaker playing the same sound will give a another gain of+3db. i.e. max 103 db at one meter listening distance. If your 2m away you listen at 97db, at 3m away 94db

If you go for a 500W per channel amp you only add 3db per speaker (gain of approx 27db). The problem is that your speaker drivers don't like to play 103db at 1meter.

The requirements according to KEF are 50-300W (60-110% of that recommended by them when it comes to amp selection). I thought that the headroom of the dual PSUs would help prevent clipping and give me more clean power (less distortion at the same level). No stadium or party level (or only short-term, to test). It's an appartment building with a 35-40 sqm open-ended room, listening distance around 3-4m.

 

[goryu]

The requirements according to KEF are 50-300W (60-110% of that recommended by them when it comes to amp selection). I thought that the headroom of the dual PSUs would help prevent clipping and give me more clean power (less distortion at the same level). No stadium or party level (or only short-term, to test). It's an appartment building with a 35-40 sqm open-ended room, listening distance around 3-4m.

You live in an apartment and you are obsessing over that last 100 watts when any of these amps under discussion will absolutely get you evicted if played at anywhere near their max output? My god man, I can't remember the last time I saw OCD taken to this level....

https://media.tenor.com/xIu0r9wlJ5kAAAAC/jack-nicholson-goos-fraba.gif

 

[soerenssen]

You live in an apartment and you are obsessing over that last 100 watts when any of these amps under discussion will absolutely get you evicted if played at anywhere near their max output? My god man, I can't remember the last time I saw OCD taken to this level....

https://media.tenor.com/xIu0r9wlJ5kAAAAC/jack-nicholson-goos-fraba.gif

Naaah, it's not about that. I just don't want to mess around with ordering multiple amps from different companies and sending them back. It's not a pair of shoes, plus they are heavy and it costs a lot to send them back to another country, plus different lead times, etc. I'm in Germany and there are no assemblers here (at least I'm not aware of it). I'm at the very beginning of this journey and I don't have your level of experience, but I know that I'm in the right place, there are lots of useful info and advice one can get here for sure. Apologies if I've been asking basically the same question over and over again.

I have a stereo NCx500 here, I'm waiting for a Denon x4800h to arrive, so I can test it with the KEFs, to see how easily it can drive them. No, I won't be evicted, because I won't listen to them loud. I also have a cat and a dog here. I'm considering the dual mono only because of longevity, headroom (IF required, even at lower volume, for less distortion - again, it's a question mark) and according to Hypex they sound better (I asked them). I'll have a dedicated stereo setup later on, but for now, the Denon will serve as a DAC/pre-amp temporarily.

 

[David_M]

I've noticed for all/most of the Purifi builds, the speaker wires from the main board to the output connectors are missized, too thin, I believe. They look like 14-gauge wire, which is recommended for 15A rms. But the 1ET400 and 7040 are capable of up to 30A rms in low impedances, which would require thicker 10 gauge wire. Why not use the wire size that matches the current output?

PS
And as a pet peeve of mine, shame on those manufacturers that don't twist their + and - speaker wires going to their respective output connectors in order to reduce radiated EMI!!! I see these long, high-current, high-slew-rate antennas passing over low-voltage buffer boards, feeding the unwanted radiated EMI and subsequent conducted currents and voltages back into the buffer boards! The EE in me says cringes deeply and says yuck! These people are clueless about the fundamental principles of EMI. Just assemblers of parts to make an amp. I will not buy from such folks, even though the price is good and the box chassis looks pretty.

For those who don't understand, + and - currents flowing in twisted wires cancel out their opposing radiated alternating magnetic fields ==> no currents/voltages induced into the sensitive low voltage buffer board.

 

[boXem]

I've noticed for all/most of the Purifi builds, the speaker wires from the main board to the output connectors are missized, too thin, I believe. They look like 14-gauge wire, which is recommended for 15A rms. But the 1ET400 and 7040 are capable of up to 30A rms in low impedances, which would require thicker 10 gauge wire. Why not use the wire size that matches the current output?

The 1ET400A is capable of 15A RMS with peaks at 25 A, thus 14 gauge is enough.
The 1ET7040SA is capable of 22 A RMS with peaks at 40 A. Although 14 gauge would still be enough due to the very short length, we are using 11 gauge at boXem.

 

[David_M]

Are they any credibly audible differences between the 1ET400A and the 1ET7040SA amplifiers, assuming both use similar buffer boards? Can you easily tell them apart?

Ditto for the NCx500 amps as well.

 

[boXem]

Are they any credibly audible differences between the 1ET400A and the 1ET7040SA amplifiers, assuming both use similar buffer boards? Can you easily tell them apart?

Ditto for the NCx500 amps as well.

Between the 1ET400A and the 1ET7040SA, no audible difference, unless the load is too low VS listening level. In this rare case the 1ET400A can shut down for self protection, which is frankly audible. We have one customer who experienced this.
I personally hear a slight difference between Eigentakt and Ncore. Sighted.

 

[mk1classic]

An in this part of the forum, the Eigentakt modules of course are "best"

 

[Xcaliber]

For the stereo 1ET7040SA, looks like there are three options in similar price range but they use different PSU:

Apollon use 63Vdc Hypex SMPS1200A400 PSU
Audiophonics HPA-S500ET use a 70Vdc proprietary PSU
VTV use Micro Audio's 70v SMPS1k-PFCR2


It looks like Audiphonics offer the best value? seems to have higher output and cheapest of the three.

 

[welwynnick]

The Buckeye PURIFI 1ET7040SA Monoblock V2 also uses a PSU with a higher output voltage:

VERSION 2 UPDATE: We have updated our 1ET7040SA Mono amplifier to now use a Micro Audio SMPS (model SMPS1k-PFCR2). Compared to our previous v1 model using a Hypex SMPS1200A400, the new v2 model using the Micro Audio SMPS is able to drive the Purifi 1ET7040SA module to full rated power output, unlike most of our competitors.

Buckeye Amps

Buckeye Amps utilizes the most advanced audio amplifier technologies available. Authorized seller for Hypex and Purifi Class D amplifiers. Based in the US. Free shipping and worldwide service!

www.buckeyeamp.com