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Buckeye Amps: Purifi Mono, 2ch, and 3ch Official Thread

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For a monoblock but not in a stereo application though right?
Mostly correct. In a monoblock 1ET7040SA configuration, the SMPS1200 is more than enough power.

However, for the 1ET7040SA stereo scenario, the SMPS1200 would not be enough power for 2ohm loads, but would be fine for 4/8ohm loads.
 

goryu

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I just checked and I am hearing that new Purifi 7040 needs 75 volts to reach full rated power but the power supply from Hypex smps 1200a400 only puts out 64 volts, while the smps 1200a700 puts out 85 volts, which would be too much. How does this reach rated power with the Hypex smps 1200a400, even in a mono mode, if the voltage output is below that required for full power?
 
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Meanpeak

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I just checked and I am hearing that new Purifi 7040 needs 75 volts to reach full rated power but the power supply from Hypex smps 1200a400 only puts out 64 volts, while the smps 1200a700 puts out 85 volts, which would be too much. How does this reach rated power with the Hypex smps 1200a400, even in a mono mode, if the voltage output is below that required for full power?

You may take a look at this supply. it's available in +-70VDC in the selection, as far as I know they can customize it for you.


You will get the same output voltage even if your line voltage goes down to 100VAC or up to 260VAC
 

goryu

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You may take a look at this supply. it's available in +-70VDC in the selection, as far as I know they can customize it for you.


You will get the same output voltage even if your line voltage goes down to 100VAC or up to 260VAC

That won't get you to full rated power either at 70V without customization from the manufacturer. Since the amp module from Purifi is only available to OEM's, this might be of interest to them.
 

Meanpeak

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That won't get you to full rated power either at 70V without customization from the manufacturer. Since the amp module from Purifi is only available to OEM's, this might be of interest to them.
That manufacturer can build +-75V I think, still, you have to check

If you don't get the full output power with that supply, then make sure that the Hypex will give you even worse results, especially at 120VAC
 
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I just checked and I am hearing that new Purifi 7040 needs 75 volts to reach full rated power but the power supply from Hypex smps 1200a400 only puts out 64 volts, while the smps 1200a700 puts out 85 volts, which would be too much. How does this reach rated power with the Hypex smps 1200a400, even in a mono mode, if the voltage output is below that required for full power?
Let me double check something and I will get back to you with a correct answer (on my end).
 

Meanpeak

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That won't get you to full rated power either at 70V without customization from the manufacturer. Since the amp module from Purifi is only available to OEM's, this might be of interest to them.
If I understand you correctly, then all those manufacturers who are selling or going to sell any amplifiers with the 1ET7040SA modules will be selling it by misleading the customers. Specially if the SMPS1200 from Hypex is +-64 and subject to the AC line variations.

For example if my AC line voltage is 225VAC, and at other place 240VAC what do you expect?
 

goryu

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Output voltage in the data sheet mentions that it is proportional to the line input voltage. Even if your line voltage is at the maximum allowed below, you will not be able to drive the 7040 amp module to full power with the Hypex supply. With normal line voltages, the max output should be derated 12%-15% if using the 1200a400 power supply so maybe 800 watts max at 2 ohm versus 450 watts max at 2 ohm for the 400A module. At 4 and 8 ohms, it would be on par with the 400A amp, so unless you have large, low impedance loads, the 7040 isn't getting you anything more than the 400A module offers power-wise. Distortion seems a bit worse than the 400A.




SMPS1200A400
10xx 20-07-2021 5
3 Electrical Specifications
3.1 Power Specifications
Parameter Conditions Symbol Min Typ Max Unit Note
High Line Input Voltage - VB 180 230 264 Vac 1)
Low Line Input Voltage VB,FP 90 115 132 Vac 1
3.2 General Performance Data
Parameter Conditions Symbol Min Typ Max Unit Note
Output Voltage Main A400, symmetric VOUT 2x49 2x63 2x72 Vdc 1), 2)


Note 1: Output voltage is proportional to the mains line voltage
([email protected], [email protected], [email protected]).
Note 2: These outputs are fully long term shortcut protected: outputs to ground, output to output.
 

KMO

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I just checked and I am hearing at that new Purifi 7040 needs 75 volts to reach full rated power but the power supply from Hypex smps 1200a400 only puts out 64 volts, while the smps 1200a700 puts out 85 volts, which would be too much. How does this reach rated power with the Hypex smps 1200a400, even in a mono mode, if the voltage output is below that required for full power?
Oops, delayed post - this didn't go through earlier. Some people have already said some of this. Nevertheless...

Rated power is at the nominal 70 volts (the 70 in its name). 75V is the "absolute maximum" voltage - you wouldn't want to be feeding it that.

But given the 63V of the SMPS1200A400, the graph in the 1ET7040SA datasheet suggests you'd get 200W(8ohm)/400W(4ohm)/750W(2ohm) at that supply voltage, rather than 250/500/900.

1661715316106.png


My understanding was some other suppliers are turning to non-Hypex power supplies.

Note that most people supplying the 1ET400A may not be quite getting its rated power out either - it's nominally 65V, but it's usually driven with one of Hypex's slightly lower 63V supplies.

1661748960062.png


Mind you, both datasheets have graphs that don't precisely match the headline power specs if you look very closely. On that graph you see the headline [email protected] and [email protected] at 65V and 63V respectively, suggesting slightly inconsistent testing for the headline numbers, or some deviation between a "theoretical" graph and real life.
 
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KMO

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For example if my AC line voltage is 225VAC, and at other place 240VAC what do you expect?
My first thought is you'd probably want a 230V PSU proportional to line voltage, and nominally 70V. Then you'd be on-spec at 230V, and you'd be varying between 67V to 73V from 220V to 240V. You'd be out-of-spec on the 1ET7040SA once you hit 247V volts though, exceeding 75V.

Apparently nominal tolerance on mains is actually quite lax in a lot of places. One bit of googling suggests 217-253V for UK, and it's not the worst. So the 75V absolute maximum isn't leaving you quite enough slack for the nominal 70V.

The 1ET400A is a lot better - it has the same 75V absolute max, but given 65V nominal you'd have to hit 265V on the mains to overdrive it. Shouldn't be possible without a mains fault, and you're probably out of spec on the PSU by that point too. (Would be on the SMPS1200A400).

If I was a 1ET7040SA builder, I'd probably want to prod Purifi about its 75V max. Don't think it's high enough to totally safely fit a 70V supply.

Edit: And the recommended max is even tighter at 73.5V. At that point, you just can't be using a "proportional to input" supply, at least not with a nominal 230V = 70V. Getting rated power out of this module is going to be tricky...
 
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goryu

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My first thought is you'd probably want a 230V PSU proportional to line voltage, and nominally 70V. Then you'd be on-spec at 230V, and you'd be varying between 67V to 73V from 220V to 240V. You'd be out-of-spec on the 1ET7040SA once you hit 247V volts though, exceeding 75V.

Apparently nominal tolerance on mains is actually quite lax in a lot of places. One bit of googling suggests 217-253V for UK, and it's not the worst. So the 75V absolute maximum isn't leaving you quite enough slack for the nominal 70V.

The 1ET400A is a lot better - it has the same 75V absolute max, but given 65V nominal you'd have to hit 265V on the mains to overdrive it. Shouldn't be possible without a mains fault, and you're probably out of spec on the PSU by that point too. (Would be on the SMPS1200A400).

If I was a 1ET7040SA builder, I'd probably want to prod Purifi about its 75V max. Don't think it's high enough to totally safely fit a 70V supply.

Edit: And the recommended max is even tighter at 73.5V. At that point, you just can't be using a "proportional to input" supply, at least not with a nominal 230V = 70V. Getting rated power out of this module is going to be tricky...


Indeed, but other than the fact that these 1ET7040SA modules aren't going to meet their rated power with the Hypex supply, the important take away is that unless you have 2 ohm loads to drive, the 1ET7040SA isn't going to do anything for you that the cheaper and better performing 1ET400A won't do. It also bears mentioning that the 1200a400 supply does allow the 1ET400A to reach rated power, at least in the US, where the mains is a nominal 120V, not the 115V as speced in the Hypex data sheet.

I agree that until manufacturers start supplying the 1ET7040SA modules with a different smps, it won't be producing rated power with the Hypex 1200a400 supply though in fairness for those needing more power at 2 ohms, it will still produce nearly double at that load in comparison to the 1ET400A.
 
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After some follow-up with Purifi:

While the SMPS1200a400 does not provide the recommended +/-70V, it currently comes "closest" to what the 1ET7040SA can handle.

I am updating my specs on the mono 1ET7040SA to acknowledge more realistic power output due to the lesser voltage. Never was my intention to mislead and I appreciate the error being pointed out.
 

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My first thought is you'd probably want a 230V PSU proportional to line voltage, and nominally 70V. Then you'd be on-spec at 230V, and you'd be varying between 67V to 73V from 220V to 240V. You'd be out-of-spec on the 1ET7040SA once you hit 247V volts though, exceeding 75V.

Apparently nominal tolerance on mains is actually quite lax in a lot of places. One bit of googling suggests 217-253V for UK, and it's not the worst. So the 75V absolute maximum isn't leaving you quite enough slack for the nominal 70V.

The 1ET400A is a lot better - it has the same 75V absolute max, but given 65V nominal you'd have to hit 265V on the mains to overdrive it. Shouldn't be possible without a mains fault, and you're probably out of spec on the PSU by that point too. (Would be on the SMPS1200A400).

If I was a 1ET7040SA builder, I'd probably want to prod Purifi about its 75V max. Don't think it's high enough to totally safely fit a 70V supply.

Edit: And the recommended max is even tighter at 73.5V. At that point, you just can't be using a "proportional to input" supply, at least not with a nominal 230V = 70V. Getting rated power out of this module is going to be tricky...
It does seem that the Purifi amplifiers deserve better power supplies than the Hypex unregulated units. Perhaps that’s why March audio have their own SMPS which I imagine are regulated since they run from 100-240V.


Not sure what rail voltages result though but Alan March claims 250W/8 Ohm which suggests around +/-70V
His IET400 amps also use a regulated supply but their power output suggests a supply nearer the +/-65V nominal. Perhaps just by adjustment of the regulator control voltage?
 

goryu

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It does seem that the Purifi amplifiers deserve better power supplies than the Hypex unregulated units. Perhaps that’s why March audio have their own SMPS which I imagine are regulated since they run from 100-240V.


Not sure what rail voltages result though but Alan March claims 250W/8 Ohm which suggests around +/-70V
His IET400 amps also use a regulated supply but their power output suggests a supply nearer the +/-65V nominal. Perhaps just by adjustment of the regulator control voltage?


Not sure if I would say "better", perhaps "more appropriate to their capabilities". Disappointing that Purifi keeps turning out drivers and amps but has yet to deliver on the promised smps for their amps.
 

Espiritiv

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What is the current wait time on one of these 1ET400A 3CH amps? Would a 5CH be an option (or even fit) in the Rack Mount case?
 

Espiritiv

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After some follow-up with Purifi:

While the SMPS1200a400 does not provide the recommended +/-70V, it currently comes "closest" to what the 1ET7040SA can handle.

I am updating my specs on the mono 1ET7040SA to acknowledge more realistic power output due to the lesser voltage. Never was my intention to mislead and I appreciate the error being pointed out.
Don't forget to update the other part of the website to match the product pages.
1661796117496.png
 
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