• 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!

$500 amplifiers to test and review?

You have already, in the form of the PS Audio Sprout 100. Although, I personally wouldn't mind seeing a few more tested should the opportunity arise... :cool:


https://www.audiosciencereview.com/...-and-measurements-of-ps-audio-sprout100.7049/

Not sure of the specific ICEPower module used in the Sprout 100, but a more interesting ICEPower-based amp to test (imo) is the Emotiva PA-1. This monoblock amp uses an ICEPower 300AS1 module, which is supposedly one of their better performing amp modules.
 
Not sure of the specific ICEPower module used in the Sprout 100, but a more interesting ICEPower-based amp to test (imo) is the Emotiva PA-1. This monoblock amp uses an ICEPower 300AS1 module, which is supposedly one of their better performing amp modules.
Yeh, someone was kind enough to contact them to send me a unit and they answered that I should buy the Emotiva! I might breakdown and do that....
 
https://www.ilounge.com/reviews/emotiva-pa-1-speaker-amplifier

Optimized to see better the details

Emotiva-PA-1-inside.jpg


ICEPower 300ASC

[PDF] http://sound-power.ru/files/doc/ICEpower300ASC_Datasheet_Preliminary_20140214.pdf

ICEPower-300ASC-frequency-phase.png


https://www.diyaudio.com/forums/solid-state/338814-lateral-cfa-120w-bsa-post5821783.html
 
Last edited:
  • Like
Reactions: trl
[...]Side Note: I think Guntar Smits video on "The Best Amplifier in the World" was interesting on this topic. [...]

This really worth posting here:

23C81B35-483F-420E-9023-83ED9F57BD94.png

So testing with sines is indeed a good thing, so probably an amp able to deliver power with less than 0.1% THD (or even better, THD+N less than 0.1%) seems good enough.
 
And not only a good THD is important. How much? I do not know but at least 0.1% THD+N at 1 watt/8 Ohms would be required in SS amplifiers of a certain price I think.

Some diyers/builders defend that the harmonic profile must be monotonically decreasing. Always H2 > H3. And ALL > 90 dB or with H2 above and the rest below, at the pleasure of the designer or consumer. And that this is more important than getting THD+N from 0.01%. There is a discussion about it.

What I do have clear is that an amplifier H3 > H2, with H3 < 90 dB is a bad choice. At least with acoustic instruments.
 
  • Like
Reactions: trl
How much power?

https://www.doctorproaudio.com/content.php?2273-calculators-proaudio-sound-dmx&langid=1#calc_spl

In my measurements, I usually listen to 65 dBSPL on average. Many tracks have at least one DR 15, so the sum is 80 dBSPL.

80 dBSPL average in a home room is very high. With DR15 -> 95 dBSPL

I have KEF Q100 with true sensitivity of 85 dB/W/m.

index.php


https://www.doctorproaudio.com/content.php?2273-calculators-proaudio-sound-dmx&langid=1#calc_spl

KEF-Q100-85dB-95dBSPL-50watts-3m-random_phase.png


In phase (equidistant from the speakers: + 3 dB): 98 dBSPL.

And, very important, the min impedance is about 3.9 Ohms. Then the 50 watts must be at 4 Ohms with KEF Q100.

Interesting that the power needed to cover the peaks is not achieved by squeezing the amplifier -> a SS amplifier with 100 watts at 4 Ohms at 0.1% THD is a very good choice for those conditions. That is why I had to give up building a very very very interesting class A 19-watt amplifier (ALPHA 20).


Moral, before buying loudspeakers, better choose among those that have measurements because the manufacturers tend to lie.
 
Last edited:
  • Like
Reactions: trl
A good example of H3 dominant is the expensive Pass Laboratories INT-60 integrated amplifier.

https://www.stereophile.com/content/pass-laboratories-int-60-integrated-amplifier-measurements

1116PInt60fig10.jpg


Fig.10 Pass Labs INT-60, spectrum of 1kHz sinewave, DC–1kHz, at 20W into 8 ohms (linear frequency scale).

Worst:

1116PInt60fig11.jpg


Fig.11 Pass Labs INT-60, HF intermodulation spectrum, DC–30kHz, 19+20kHz at 40W peak into 4 ohms (linear frequency scale).

...As I have come to expect from Pass Laboratories, the INT-60 offered respectable measured performance that included a careful balance of the consequences of the limited amount of negative feedback used. I'm a little suspicious of the change from predominantly second- to third-order harmonic distortion as the frequency rises, as I feel that amplifiers that maintain a constant distortion signature sound better. However, it's as fair to concede that I have no actual evidence that that is true in this case as it is to note that Herb Reichert loved the INT-60's sound.—John Atkinson

That is why measurements are so important, money is not the panacea in audio. Excellence has to be demonstrated day by day, it is not worth living from past glories.
 
Last edited:
This really worth posting here:

View attachment 27776
Note: I mistakenly linked to the Latvian(German?) audio version. The English Version of the World's Best Amplifier Link.

I think Guntar's Smits Youtube channel is enlightening and seems objective, so worth viewing. His step by step video on how to DIY build the above reference Best Amplifier (meaning good enough so that you likely will not hear any issues) is great, particularly for those like me whose DIY skills are a bit rusty. I actually ended up building a TPA3255 based amp, but the construction process was near identical.
 
Last edited:
Note: I mistakenly linked to the Latvian(German?) audio version. The English Version of the World's Best Amplifier Link.

I think Guntar's Smits Youtube channel is enlightening and seems objective, so worth viewing. His step by step video on how to DIY build the above reference Best Amplifier (meaning good enough so that you likely will not hear any issues)is great, particularly for those like me whose DIY skills are a bit rusty. I actually ended up building a TPA3255 based amp, but the construction process was near identical.
How about someone makes this Class D amp and sends it to Amir? :)
It looks promising to me, but that says nothing.
 
It is just based on an ICE module so is not the same as their DACs which they design.

But yes, would be good to test some ICE based amplifiers.

From what I read the ice modules are fairly picky about their input impedance so a good buffer stage is needed before them to get the best sound.

The amps with the modules on ebay seem to sell for pretty good multiples of the price of just the module on ebay.
The modules have interested me for some time but I'm much more a fan of integrated amps anymore. I'm too lazy to turn on more than one thing ;) and preamps get pretty expensive too.

The ICE module numbering gets confusing too. I'm not sure what the different numbering suffixes mean either. Is an AS1 better than an ASX2?
 
Last edited:
How about someone makes this Class D amp and sends it to Amir? :)
It looks promising to me, but that says nothing.
PSU no longer available - at least I've not found it available anywhere in a quick search. Any suggestions for an alternative? Amp module at DigiKey - it needs +/-45V - +/-60V and you really want to be able to shut down the psu when the amp detects dc offset on the outputs as the protection on the amp board won't help if an output transistor fails short. I've repaired a guitar amp that hit this failure mode and blew speakers.

The TPA3255 from 3E-Audio that @GGroch used seems a better bet all round to me. Half the price for the amp board, <half the residual noise and lower distortion, and the protection appears more comprehensive from the datasheet.
 
PSU no longer available - at least I've not found it available anywhere in a quick search...

I do not see the exact model either...although Parts Express used to carry it. I expect Guntar would know if comparable replacements were available.
The one time I messaged him through his Youtube contact he responded quickly.

As he points out in the video, one benefit of the IRAUDAMP7s is that International Rectifier licensed the entire board to some Chinese manufacturers...so you can get what should be identical clones cheaper on eBay (like $66).

I purchased the chassis he shows in the DIY video from him on ebay last month because it fit my 3eAudio boards great and was just $29 shipped. I do not see it listed now. I am very happy with the subjective performance of the 3e-Audio TPA3255 but would also be interested in how it compares to an IRAUDAMP7.
 
PSU no longer available - at least I've not found it available anywhere in a quick search. Any suggestions for an alternative? Amp module at DigiKey - it needs +/-45V - +/-60V and you really want to be able to shut down the psu when the amp detects dc offset on the outputs as the protection on the amp board won't help if an output transistor fails short. I've repaired a guitar amp that hit this failure mode and blew speakers.

The TPA3255 from 3E-Audio that @GGroch used seems a better bet all round to me. Half the price for the amp board, <half the residual noise and lower distortion, and the protection appears more comprehensive from the datasheet.
Do you know of any good boards with this chip? I don't dare to look at Diyaudio.com...
Which board did you use @GGroch?
 
3E-Audio TPA3255 looks from the limited measurements in the datasheet like it matches TI's specs. PSU is theirs too. I'm not aware of any independent measurements of this board.

You can get the TI EVM from DigiKey - it's recently been retested by QuantAsylum, as has one of the cheap generic ebay boards. Note the difference in performance, and the lower spec regulator that means the cheap board needs to run at reduced voltage so can't meet its claimed power output.
 
How about the TPA3521 chip/boards? I read they are a bit better for 4 Ohm loads.
 
How about the TPA3521 chip/boards? I read they are a bit better for 4 Ohm loads.
3E have 3 boards with different channel counts for that chip, and TI have an EVM. I don't know of independent measurements of either, so you'll have to check the datasheets for 4R/8R relative performance. I've not seen any generic boards for that one.
 
Back
Top Bottom