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Monolith: Transformers Feeding Amp Modules

Zing

Zing

Retired Admin
Superstar
The Monolith 5x200 amp has two transformers: one 1230VA and one 1025VA. The transformer on the right (in photo) appears to be feeding three modules so I'm assuming that is the larger of the two. In the photo of the rear of the amp, you can see the (recommended/designer intended??) order for connecting speakers is, (left to right) Right Surround, Right, Center, Left, Left Surround. That means the RS, R, and C are fed by the larger transformer (@410VA) and the L and LS are fed by the smaller (@512.5VA).

My OCD is having fits trying to process why that is. Wouldn't be best to feed the surround amps with the lesser voltage since they produce the least amount of content?

155935.jpg


155934.jpg
 
You like those pictures? I took them. I also designed and wrote the firmware code for that small PCB on the left. :bouncygrin:

The transformers both have the same voltage. Only the current capacity of the smaller one is less because its feeding fewer channels. The layout of the channels is somewhat arbitrary - they all have the same power.
 
MakeMineVinyl said:
The layout of the channels is somewhat arbitrary - they all have the same power.
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That's good to know. Using the inside photo as a basis, if I bought that amp, I probably would've connected my front three speakers to the amps fed by the larger one thinking I was somehow gaining something.
 
Zing said:
That's good to know. Using the inside photo as a basis, if I bought that amp, I probably would've connected my front three speakers to the amps fed by the larger one thinking I was somehow gaining something.
Click to expand...
You wouldn't be gaining anything. The channels and their power supply voltages all end up the same. By the way, Monoprice just came out with a class D 8 channel amp which is also made by ATI (I worked on that one too) if you want the efficiency.
 
Class D is not my thing, despite its advances in recent years. I'm pretty much an AB guy. Or at least I have been.

I'm still using a pair of Parasound A23's to power my mains and surrounds and an Emotiva monobloc for the center. All 5 speakers are 85-88dB Dynaudio and I've been lusting after an A21 for the mains for years. But as the years add up (and the hearing declines), I'm thinking a less expensive multichannel amp is the smarter play as I doubt I'd hear any benefits from a robust 2 channel amp.
 
Class D has come a very long way. Every speaker in my house runs off Class D amps, except for the ones in my main system. I have zero complaints about the sound.
 
Class D has gotten very good but there is still a place for class A/B. ATI makes both. Personally, with the exception of my subwoofer amplifier which is class D (Behringer NX-6000), all my amplifiers are vacuum tube which works great since my main speakers are large horns and only need a couple watts.
 
I've been testing the PureFi class-D amp modules and thus far I cannot think of any pure constant voltage amp which comes close to comparing in performance & sound quality. Nearly every aspect of a constant voltage amp which impacts performance has been address to a degree these are darned near perfect. Pretty cool, but still in review.
 
Flint said:
I've been testing the PureFi class-D amp modules and thus far I cannot think of any pure constant voltage amp which comes close to comparing in performance & sound quality. Nearly every aspect of a constant voltage amp which impacts performance has been address to a degree these are darned near perfect. Pretty cool, but still in review.
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Can you share with us some plots of your results vs an nCore module? I'd like to compare what you've gotten to the AP test's we've done at our factory to see if we should consider changing from nCore. Hypex hasn't stood still by any means and has incorporated some interesting ideas. Still, PuriFi has an outstanding reputation is probably state of the art, at least for the time being. We're currently using customized (from Hypex) NC502 and NC252 modules to ODM amplifiers for Monoprice, and NC500 series modules for ATI, Theta and a couple OEM partners. One advantage for the nCore modules is their i2C buss implementation which we use for status/fault diagnosis and I don't know if PuriFi has that. As is usual, we add our own input stages and protection/soft start/fault diagnosis circuitry managed by a microcontroller.
 
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MakeMineVinyl said:
Can you share with us some plots of your results vs an nCore module? I'd like to compare what you've gotten to the AP test's we've done at our factory to see if we should consider changing from nCore. Hypex hasn't stood still by any means and has incorporated some interesting ideas. Still, PuriFi has an outstanding reputation is probably state of the art, at least for the time being. We're currently using customized (from Hypex) NC502 and NC252 modules to ODM amplifiers for Monoprice, and NC500 series modules for ATI, Theta and a couple OEM partners. One advantage for the nCore modules is their i2C buss implementation which we use for status/fault diagnosis and I don't know if PuriFi has that. As is usual, we add our own input stages and protection/soft start/fault diagnosis circuitry managed by a microcontroller.
Click to expand...
I have very little data to share as I don't have any lab grade measurement gear. I am 100% certain your AP tests are far better than anything I could provide. I have a pair of reference architecture modules mounted in a DIY chassis which a friend has loaned me and most of what I am doing is blind comparisons to my other amps and a few borrowed higher end "audiophile" amps. What I am noticing, which is subjective, is lack of "character" from the PureFi modules - as in I cannot explain any characteristic sound or perceive any such sound. Whereas, the other amps all present something I think I can consistently hear (using listener-blind switching) a certain character in the other amps. I am still in early days of playing with them, so I am not 100% confident in my initial results.

That said, the noise floor is significantly lower on the PureFi modules versus all the other models when adjusted for the same gain, and the PureFi modules don't seem to "strain" (a subjective observation) at all at high levels compared to most of the other amps when pushed hard. The sole Professional Amp (QSC RMX-2450a) in the room also didn't seem to strain, but the noise floor was unacceptable for high fidelity use. The Halo amp did pretty well, but the noise floor was high relative to the PureFi.

All of that said, I mentioned this to say that my opinion on Class-D amps has completely flipped from 10 years ago when I was ranting about how awful they were and suggesting people avoid them.
 
Flint said:
I have very little data to share as I don't have any lab grade measurement gear. I am 100% certain your AP tests are far better than anything I could provide. I have a pair of reference architecture modules mounted in a DIY chassis which a friend has loaned me and most of what I am doing is blind comparisons to my other amps and a few borrowed higher end "audiophile" amps. What I am noticing, which is subjective, is lack of "character" from the PureFi modules - as in I cannot explain any characteristic sound or perceive any such sound. Whereas, the other amps all present something I think I can consistently hear (using listener-blind switching) a certain character in the other amps. I am still in early days of playing with them, so I am not 100% confident in my initial results.

That said, the noise floor is significantly lower on the PureFi modules versus all the other models when adjusted for the same gain, and the PureFi modules don't seem to "strain" (a subjective observation) at all at high levels compared to most of the other amps when pushed hard. The sole Professional Amp (QSC RMX-2450a) in the room also didn't seem to strain, but the noise floor was unacceptable for high fidelity use. The Halo amp did pretty well, but the noise floor was high relative to the PureFi.

All of that said, I mentioned this to say that my opinion on Class-D amps has completely flipped from 10 years ago when I was ranting about how awful they were and suggesting people avoid them.
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Class D can be very, very good and is probably the best choice for the majority of consumers. Class D is more like an appliance, and that is a plus for somebody who just wants to listen to music and not worry about the technical details. It is also is more ecologically friendly. By the way, the noise differences you are hearing might well be the bespoke input stages.

That said, class A/B has its place and is best for the person who enjoys the physical presence and pride of ownership of their amplifiers. These people are more likely to have their amplification front-and-center in their rigs.

On the class A/B front, there is some quite exciting technology coming out from ATI which I have been developing for the last couple years (and delayed due to Covid). Its going to be awhile because we're swamped already, but its coming.
 
I have installed several systems in boats and cars using predominantly the Alpine PDX9 class D amp with with amazing results.
No one has been disappointed or been able to discern the difference. They are wowed by the power and size compared their class A/B counterparts.
Car Fi and boats are completely different applications but they are proving themselves worth their weight (savings).
 
MakeMineVinyl said:
Class D can be very, very good and is probably the best choice for the majority of consumers. Class D is more like an appliance, and that is a plus for somebody who just wants to listen to music and not worry about the technical details. It is also is more ecologically friendly. By the way, the noise differences you are hearing might well be the bespoke input stages.

That said, class A/B has its place and is best for the person who enjoys the physical presence and pride of ownership of their amplifiers. These people are more likely to have their amplification front-and-center in their rigs.

On the class A/B front, there is some quite exciting technology coming out from ATI which I have been developing for the last couple years (and delayed due to Covid). Its going to be awhile because we're swamped already, but its coming.
Click to expand...
I am excited to see the new A/B designs, be sure to let us know when info is available.

I am not dismissing class A/B at all, I just no longer think class-D is a joke. Even going so far as to say that in many cases class-D amplification can be the absolute best option for high fidelity results.
 
Flint said:
I am not dismissing class A/B at all, I just no longer think class-D is a joke. Even going so far as to say that in many cases class-D amplification can be the absolute best option for high fidelity results.
Click to expand...
They can be, which is why we manufacture both class A/B and class D. Personally, I place the dividing line between class A/B and class D recommendation at going for class D with less efficient speakers and class A/B with the current higher efficiency speakers (>90dB/w). For instance it would be insanity for me to use class D with my 107dB/w high frequency compression drivers. Besides the danger of blowing them to smithereens, the residual noise and grit would be quite noticeable.
 
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