• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

Buckeye Purifi Eigentakt 1ET9040BA monoblock power amplifier Stereophile Measurements

Status
Not open for further replies.
You can't determine that 1000 watts is loud.

Besides, that's not the main point.
Yes - The point was the PSU that was mentioned won't even allow the 1.4Kw module to reach full power. Arguing that an amp that big is "too loud" is way OT, and silly IMO :) (an amp designed to produce 1.4Kw should be paired with a PSU that will supply it appropriately, not paired with a down-sized PSU because it will be "too loud"). But it was also mentioned that Buckeye has not seen specific recommendation of said PSU with said module. So seems like a big case of "I dunno" :oops:
 
You can't simply determine that 1000 watts is loud.
Besides, that's not the main point.

If we are talking about steady state, then it seems like it should be pretty loud.

If we are talking about transients then I would not really worry about whether the supply can send endless current in, as there will be gaps in the output.

You chart has a 20 dB headroom number in there, so that implies that it is not steady-state RMS power.
So then the RMS power of 1400 may not be able to be met, but there might be peaks where the 1400 can be met… assuming that there are some capacitors in the device to supply it.
 
You should use a more realistic calculator. Here is just one example:
View attachment 420204

For program material with a CF = 20 it would be 1.8kW ;)
And this consideration does not even take into account a room correction such as Dirac Live, which may also compensate for sinks!
The calculator may be realistic but sure seems like you're putting in numbers designed to make sure you need a lot of power. Let me see what I get for something resembling my situation...

1736578927313.png


66.4W? I can get by with a baby amplifier apparently!
 
If we are talking about steady state, then it seems like it should be pretty loud.

If we are talking about transients then I would not really worry about whether the supply can send endless current in, as there will be gaps in the output.

You chart has a 20 dB headroom number in there, so that implies that it is not steady-state RMS power.
So then the RMS power of 1400 may not be able to be met, but there might be peaks where the 1400 can be met… assuming that there are some capacitors in the device to supply it.
You initially brought up SPL in relation to power, but it’s difficult to make meaningful comparisons here. For instance, what might require 1000 W for one setup could need only 6 W for another.
It would not be productive to continue discussing SPL and power, as extreme examples can be found for both cases.

Let’s refocus on the original topic of power supplies rather than SPL.
 
66.4W? I can get by with a baby amplifier apparently!
Try CF = 20.
And as I have already said, the influence of tone controls/DSPs should not be neglected.
 
Try CF = 20.
And as I have already said, the influence of tone controls/DSPs should not be neglected.
And what about the house curve?
 
Does anyone know why Purifi recommends the Hypex 1200W power supply, knowing it cannot provide the full rated power of 1400W into 2 ohms of the 9040BA module? With this Hypex power supply, the 9040 is able to deliver a maximum of 1050W to 1100W into 2 ohms. Why not recommend another one, like the Microaudio 1500W PS, able to deliver the spec'd 1400W?

Does Purifi have some form of a contractual relationship with Hypex to only use their power supplies, maybe due to the former history of the design engineers with Hypex?
The latter may play a role, but the true reason likely is that it simply doesn't matter in practice. 1400W vs 1200W is only one measly dB more SPL, and 2Ohm speakers are not very common. IMHO this is a complete non-issue. A bigger concern (in relative terms), mentioned in a previous post, is that the Hypex supplies scale output voltage with mains voltage and that may cause a much bigger range of available max powers. Especially Japanese customers with their 100V lines, sometimes even 90 only, will have a disadvantage. Does it really matter in practice? I highly doubt it.
 
The latter may play a role, but the true reason likely is that it simply doesn't matter in practice. 1400W vs 1200W is only one measly dB more SPL, and 2Ohm speakers are not very common. IMHO this is a complete non-issue. A bigger concern (in relative terms), mentioned in a previous post, is that the Hypex supplies scale output voltage with mains voltage and that may cause a much bigger range of available max powers. Especially Japanese customers with their 100V lines, sometimes even 90 only, will have a disadvantage. Does it really matter in practice? I highly doubt it.
Wow - I'd call that an issue if not clearly noted. Does it change from 110/120 to 220/240 as well? Or only below 110vac? Isn't the point of "universal input voltage switching PSU's" to be capable of outputting stable voltage @ amperage within the specified input voltage range?

And while only a few hundred watts from rated power to "what you actually get" - if the amp is spec'd for 1.4kW the PSU should support that IMO. If not matched with a capable PSU, then the "amp" using the module+psu pairing should be rated/spec'd for the specific PSU is it paired with. The fact this also varies with wall voltage seems very objectionable to me. My KH150's don't do that :) (the DSP section certainly wouldn't like that!). And 2 ohm minimum impedance is not that uncommon...

Is this the only switching PSU with this behavior? What other "universal input voltage" PSU's ramp output voltage with input voltage?
 
Always read datasheet first prior to asking


There is selectable mains voltage 230/115V. However, psu is unregulated.

IMG_3569.png
 
Oh - Got it. So not a truly "universal input voltage" type PSU (like units w/o a voltage switch) - and safe to assume unregulated?
 
Discussion is going in circles again :-(
People should try to understand what datasheets are for and read them thoroughly.
https://www.audiosciencereview.com/...phile-measurements.59423/page-32#post-2188400 and following.

As for the unregulated supplies, linear transfromer supplies have always been unregulated (scaling with mains voltage) and nobody ever made a big deal of it. Also, they tend to have less load stiffness, showing more load dependency even with constant mains voltage. No big deal either.
 
Yes, just doing the maths with your example. The nominal Hypex supply voltage for rated 46v output voltage is 115v. If this reduces to 90 volts thats a 21% reduction. Output voltage would be only 36volts. This means the 8 ohm rating for the 9040 module drops from 750 watts to about 480 watts.
The 46V rating is proportional to 230V,not to 115V and also proportional to the fluctuations of each typical voltage.

PSU.PNG
 
As for the unregulated supplies, linear transfromer supplies have always been unregulated (scaling with mains voltage) and nobody ever made a big deal of it. Also, they tend to have less load stiffness, showing more load dependency even with constant mains voltage. No big deal either.

There is a big difference in peak power capability (SMPS x linear PSU) and this is especially evident at low frequencies. Attached plots are with a completely different amp, but they demonstrate loss of power at 20Hz due to insufficient SMPS LF current (energy storage) due to capacitor bank capacitance. I can see the only advantage of SMPS in much lower weight and dimensions. It is an important advantage.

SMPS_currentlimit.png
 
The Crown Macro Tech series also utilize unregulated PSU's that require transformer taps for different mains voltages. I recall some people having preferences for unregulated PSU's for sub duties (assuming an ample mains supply). Maybe due to a very low source impedance?

Fully Regulated supplies seem like a sensible solution across the board assuming they don't have a high source impedance (make it harder for the amp to pull power out of the PSU), and don't raise cost substantially over a good linear and unregulated design. In car audio - they have "CP" Constant Power amps (JL HD series, Rockford Txxx.1BDCP Sub Amps) that regulate the power supply and also modulate rail voltage to follow speaker load for a range of consistent output power from 10v-15v B+ input voltages and impedances from 1ohm to 3ohms.
 
No. The nominal 46v out is 230v on the high mains range and 115v on the low mains range. It is a manual jumper selection on the psu. I was of course assuming that if you are using in Japan at 100 volts (nominal) you would be using the low range.
The difference would be small any way.
We also have to consider any voltage drop near the PSU's limit,as always.

Edit:And the whooping over 100W of power losses up there of course,which is a far bigger problem:

thermals.PNG
 
Last edited:
The difference would be small any way.
We also have to consider any voltage drop near the PSU's limit,as always.
Or get a PSU of sufficient power capabilities?
 
The 46V rating is proportional to 230V,not to 115V and also proportional to the fluctuations of each typical voltage.
No. The nominal 46v out is 230v on the high mains range and 115v on the low mains range. It is a manual jumper selection on the psu.
Exactly.

This is how these jumpers work, enabling/disabling a voltage doubler (for the 115V range) right at the input of the supply.
The supply core doesn't even know about the input voltage and thus doesn't behave any different

1736589904665.png
 
Status
Not open for further replies.
Back
Top Bottom