Dual Merus MA12070 Amplifier Sabaj A20 fully balanced : pictures inside )

[gasolin75]

It is the new version

 

[ModDIY]

It is the new version

Is it a question?? For me??

 

[gasolin75]

Just a general answer It's the new version from hifi-express with the upgraded power supply

I go mine last month

 

[dr0ss]

Can someone who has lived with a T-amp comment on the relative 'voice' of this amp? (I ask with some trepidation, since voice is one of those things that I don't think I actually believe in...)

A couple of years ago I threw together an amp based on an TC2001/STA508 combination for a project that never came to fruition. Shortly after that the 80s-era Denon receiver that was serving as our living room amplifier died, and I swapped in my homebrew T-amp as a temporary replacement. While it drives our legacy Klipsch speakers quite easily, and it has some of the warmth we liked in the Denon, it always feels relatively 'thin', even at high volumes. The time has come to find something more permanent, and while I've been looking at newer amps from Denon (and NAD; our preamp/tuner is an NAD 1700) these Infineon-based amps are attractive from the POV of size, efficiency, and price. However, if they are on the 'cold' side compared to T-amps, I'm not interested.

 

[Moosi]

I have never heard TC/STA amps, but I'm very picky about "clinical voices" and the A20a is definately on the warm side and has a beautiful texture and detail to it, but I'm not sure about these Klipsch speakers, since I don't know them (running KEF LS50 Metas). From what I've heard about Klipsches is that they are either considered heavily distorting and harsh in terms of voices or very warm and foreward, but "very warm" is also kind of distorted isn't it. The A20a is very precise as long as you don't push it to its limits, much more than probably most if not all Denon amplifiers. So it's really up to your speakers. I would'nt even say there is much "color" to it. Just "precision". If you play a warm track, you will melt. If you play frozen shards, you will get frozen shards. If you love "warmth/distortion" and yet want to have lots of detail you could try setting up a tube preamp in front of it.

 

[dr0ss]

Thanks Moosi; my T-amp is based on a module very similar to this one. It is the baby brother of some amps discussed upthread (like the "Gremlin"), so I thought someone here might be able to say something about the difference in sound. I never meant for it to be our primary stereo amp!

Distortion is not my goal, but I like things to sound a certain way. There are many amps which on paper are perfectly linear gain machines, but people seem to detect differences in their voice. Perhaps it is imagination.

I know there are strong negative opinions about Klipsch speakers among some audiophiles, just as there are strong negative opinions about D amps among some audiophiles. I like the sound of mine (the model is KG4, with some mods to the tweeters and crossovers). When I bought them (to replace a pair of Polk Monitors) I was also considering a pair of Totems, and had recently spent some time with a friend's Spendors. These are the speakers that grabbed me. Personal taste

 

[milan616]

STA based modules have generally seen a distaste in the audiophile community, relegated to subwoofers. This can been seen in the very tepid early reaction to the SMSL SA400 (but also the price). More modern class D designs like Purifi, Hypex, the Infineon Merus here, and the TPA3255 (design dependent due to low end competition) have seen greater success in full range audio designs.

 

[Moosi]

Thanks Moosi; my T-amp is based on a module very similar to this one.

Well, any MA12070 amp, single and especially dual chip will beat this thing in about every aspect. It claims to have 80W@4ohm, but has a max. current of 3A (8A@Ma12070 which is also 80w@4ohm). This is a joke. Maybe useable on low volume with very efficient speakers, but not more. I wouldn't use this amp for anything other than a kitchen music player or an amp to deliver some ambient tunes in an elevator.

I know there are strong negative opinions about Klipsch speakers among some audiophiles, just as there are strong negative opinions about D amps among some audiophiles.

From what I hear, the MA12070 sounds not that much like a typical "D-Class", but more like an in between of A/B and D. I cannot approve this however, since I dont't own any A/B class (yet).

Interesting:
"Notably, with the multi-level modulation of the MA12070, there is no tradeoff between idle power loss and inductor cost/size, which is due to the absence of inductor ripple current under idle conditions in all configurations. Due to the high filter cutoff frequency, non-linearities of LC components have less impact on audio performance than with a conventional amplifier. Therefore, theMA12070 can operate with inexpensive iron-powder cored inductors and ceramic (X7R) filter capacitors with no significant audio performance penalty."

As far as I understand it, the "multi-level modulation" is actually kind of "simulated class A" by technical terms. In the sense that there is a "flying current" compared to a "zero or x current" with other D-Class amps, being more similar to a "linear current" of linear powered amps. Correct me if I'm wrong here.

 

[dr0ss]

Probably this is not the right thread for speculation about the quality of T-amps or Klipsch speakers. I own both, and have a good sense of the qualities and limitations. My question was for people who have firsthand experience both with Sabaj amps and either T amps or Denon or something else with a similar vocal signature, to let me know where they see the voice of the Sabaj relative to the others I mention. (Perhaps 'voice' is not a real thing, but I think it is probably as real as "musicality" which has also come up here.) And, while I'm not interested in defending my TC2001/STA508 amp (since it was a temporary/emergency replacement, my goal is to replace it, and I've already identified some weaknesses with it), it is currently driving highly efficient speakers and has no trouble loudly filling a 115 m^3 space with the knob at 30%.

 

[jokan]

Off topic, but basically the same chipsets used in different chassis.
Apologies for being slightly off topic/brand.

Internal Pic of the SMSL A0200:

The DA-9 has the PSU along a different location, specifically less than 1/4 of an inch, probably 1/8" from the LED Display Driver which is a noisy device.

I'll include a PCB shot of the DA-9 with the gaping hole where the PSU would be.
The grey stuff is the bottom, or output terminal side of the DA-9 with new, better than factory thermal grease. (literally anything other than that white grease is better than factory.)

The A0200 has a much more thought out positioning of internal components.

 

[Moosi]

Off topic, but basically the same chipsets used in different chassis.
The A0200 has a much more thought out positioning of internal components.

Thank you. I learned quite a lot by comparing all the three dual Merus amp platinas.
Things to note:

• DA-9/AO200 probably not being fully PBTL, but only BTL or in between, due to "weak" current PSU (9.4A max. of theoretically possible 16A)
• AO200 far better layout than DA-9, should result in better (best) noisefloor (of the brothers).
• AO200 is the only one using anti-jidder(?) modules on the NJRC1194 volume controller.
• A20a has probably the weakest layout in terms of noisefloor, but by far the most power due to PBTL with a 14.6A PSU. It can handle peaks down to 1.6 Ohm, which is very impressive.

If one would manage to pull the PSU of the A20a from the case and put it into a second case right next to the amp, one could argueably and possibly create the very best dual Merus amp (other than DIY from start) with the most power reserves and the best achieveable noisefloor.

 

[jokan]

Thank you. I learned quite a lot by comparing all the three dual Merus amp platinas.
Things to note:

• DA-9/AO200 probably not being fully PBTL, but only BTL or in between, due to "weak" current PSU (9.4A max. of theoretically possible 16A)
• AO200 far better layout than DA-9, should result in better (best) noisefloor (of the brothers).
• AO200 is the only one using anti-jidder(?) modules on the NJRC1194 volume controller.
• A20a has probably the weakest layout in terms of noisefloor, but by far the most power due to PBTL with a 14.6A PSU. It can handle peaks down to 1.6 Ohm, which is very impressive.

If one would manage to pull the PSU of the A20a from the case and put it into a second case right next to the amp, one could argueably and possibly create the very best dual Merus amp (other than DIY from start) with the most power reserves and the best achieveable noisefloor.

I'll link the Infineon/Merus manual to you, the 300watt power supply is literally the max for the chipsets.
The layout is better, you are 100% correct.
It is indeed quieter noise floor wise from what I can tell. Quiet passages and crescendos are more evident.
I am not entirely sure of the digital pot. That is not my area of expertise. I do wish they used a better digital volume pot.
There is ZERO advantage that I could find by upgrading the op-amps. In fact it made matter worse with the famed and much loved 1612.

Link for the Infineon Merus chipset for a single channel.

 

[Moosi]

I'll link the Infineon/Merus manual to you, the 300watt power supply is literally the max for the chipsets.

320W actually, yes. But the LOF225 PSUs used in the DA-9/AO200 amps do not reach 300W, but only 225W.

There is ZERO advantage that I could find by upgrading the op-amps. In fact it made matter worse with the famed and much loved 1612.

This may be because those op-amps in difference to other D-Class amps are not being used right before speaker-out (for those are included within the chip-IC), but before the Merus IC as far as I see through it. Since they're only used to pass-through a low-power current (+gain information) which is being amplified by other Merus internal op-amps again afterward, they're not that important since those NJRC controllers are very low THD anyways, much lower than the amp-stage. Please correct if I'm wrong.

 

[jokan]

320W actually, yes. But the LOF225 PSUs used in the DA-9/AO200 amps do not reach 300W, but only 225W.

This may be because those op-amps in difference to other D-Class amps are not being used right before speaker-out (for those are included within the chip-IC), but before the Merus IC as far as I see through it. Since they're only used to pass-through a low-power current (+gain information) which is being amplified by other Merus internal op-amps again afterward, they're not that important since those NJRC controllers are very low THD anyways, much lower than the amp-stage. Please correct if I'm wrong.

@Moosi you are correct about the power-supply, I double checked and no doubt you did too.
The DA-9 and the A0200 has slightly different op-amp configurations.
I had both amps. my A0200 is currently on it's merry way back to china from Japan via Aoshida Japan, they will take receipt of it tomorrow, they will fedex me a new amp with the display reading bluetooth instead of bluetoot! Zero other functional changes.
There is a 1678 and an ST072c. I suspect that since the DA-9 has only one of the 072c's it's for the single sub output, and the 1678 is a cheating method for creating what I call a semi-balanced output. I secretly (don't tell SMSL, or Aoshida Japan) changed the 1678's to 1612's It sounded worse by a significant margin. I tried another set of op-amps and everything was soldered correctly with full contact, but I got popping noises. that was the 1656 a bit of a hidden gem.

Yes, you are correct there are miniaturised op-amps within the chipset that we have no access to. There is no reason in my mind that they would manufacturer a chipset that is fundamentally wrong. The NJRC controller is a bit of a gripe for me as I know that there is a step up from the model they used.

I DO NOT believe you are wrong. I also don't think that we know all that there is to know about exactly what tricks that SMSL and Aoshida/SMSL used in the jumping/wiring of the chips/+programming.

There is no physical space for any other PSU in either amplifier, The case is literally full in both cases.

Let me ask you what amplifier currently on the market has the same performance as the SMSL duo, assuming they are problem free?
Aoshida is far more on top of it when it comes to customer service, at least Aoshida Hi-Fi Japan is.

I think that there is a slight level of expectation that is unreasonably being placed on the amplifiers.
Also remember that Infineon bought out International Rectifier Company from the USA. These/those people knew what they were doing maybe not on the financial end since they went under, but they manufactured some seriously high performance chips.

I'd like to set the record absolutely straight as I have said on multiple occasions. We have only the specs that are provided by SMSL/Aoshida. No 2nd or 3rd party measurements. I think it's best to wait until we get some measurements and see how it coincides with user ratings and opinions in the "real-world". If you have one, then you know, if you don't then single thing other than what is published which is seemingly not exactly how the chips are programmed or wired becomes speculation. And I am not accusing you of either. We just need a 2nd/3rd party review. That would settle a lot of the speculation. The A0200 is the best iteration I have seen thus far. I used to own a DA-8s and I ran it 24/7 with a nominal 2.7ohm load. The DA-9 and A0200 also runs at a 2.7 ohm load all day everyday. I think that's pretty stable myself. And I am notoriously hard on my equipment.

Meanwhile they're both new amplifiers. Expect them to be in production for 2 year, maybe 3. With Class-D there will always be a newer, better, greater version in less than a model year. This is inevitable.

I do agree with you however. No question in my mind, you have my agreement. Cost/space. The primary concern. Also safe voltages and current for the chips without running them at 100%. Also a lot of the specs are WITHOUT heatsinks. Both amplifiers use aluminium blocks and the chassis as a cooling system. And frankly replace the white thermal grease for a paste with a much higher rating. The standard white grease is in the super low 2's for heat rejection/absorption.

 

[Moosi]

The DA-9 and A0200 also runs at a 2.7 ohm load all day everyday.

Well, I've been reading into this subject a lot lately and here's what I found out.

In theory and only with a PBTL configuration the MA12070 can handle spikes down to 1.6 Ohm, which is very impressive considering this is lower than the TP3255-ICs can reach in PBTL (1.7Ohm), which is a 2x600W Mono@2Ohm D-Class amplifier (compared to a 2x160W Mono@2Ohm D-Class amplifier). A 1200W amp that cannot reach as down as a 320W amp, think about this. That alone to me is a display of the technological advances they made with those Merus chips.
But there is more to it.

• The MA12070 can put out 8A max. per chip (@1.6Ohm max.). Assuming that doubles in PBTL without significant loss, we have 16A of max. current output@up to 27V PVDD before entering the danger zone (>27,5V PVDD). In theory that is a total of about 432W (16A/27V) a PTBL-config Merus amplifier could possibly suck out of the PSU driven at its limits.
• [416W@26V / 384W@24V / 368W@23V / SabajA20a_stock is between 23-24V / Infineon recommends 26V]​
• 
  
• The TP3255 in PBTL can reach out/down to ~24A@56V [email protected] max. which is a staggering 1345W(!) of dynamic current that could be applied theoretically. Good luck on finding your power supplies for that sucker.

The problem with the DA-9/AO200 is that they are underpowered for a PBTL having a PSU that can only do 140W/247,5W* whereas the SabajA20a has a 200W/385W* PSU which is -power-wise- actually the perfectly suited PSU for a 24V PVDD configuration. *(Continuus/Peak before hiccup or reset)

 

[gasolin75]

i then wonder why some wants to turn up the voltage on there replacement power supply, Mission LX 3 MKII 40 is normal volume Rammstein - Deutschland (Official Video) mid 30's is normal loud, 30 is loud 20 is almost party loud, way loud for nearfield listening with rammstein, - 20 db i don't hear any distortion, -40 db my phone is peaking (sound meter) 1 feet away from my right speaker at 84 db avarage is 76db

 

[Moosi]

i then wonder why som wnat to turn up the voltage onm there replacement power supply

a) it depends a lot if not most on your speakers sensitivity how much power (peaks) you really need. 83db/1W@1m speaker needs about 4x the power than a 90db/1W speaker roughly spoken to achieve the same level of sound pressure. From 83db/1W you will have to double the output every +3db. This is of course the same with the 90db, but the 90db is starting the run from a hugely better starting position. Most people don't listen to much higher than around 95db anyways, but that counts for 1m distance which is nearfield.

• 95db with 90db speakers = ~3,5W
• 95db with 83db speakers = ~16W

b) I can only quote another user from "DIYaudio-forum": https://www.diyaudio.com/forums/pow...itability-power-supply-audio.html#post5564905
"Now, if you compute the peak current going through the supply, it is 0.5*Vs/Rload, and 6.35/2 is 3.15A, thus more than three times the average current."

Spoiler

"Some SMPS's designed explicitly for audio applications do exist, and unusually that's not ordinary audiophoolery (although this factor might creep in).
Let's take a simplified numerical example: you need to power an ideal 10W class B amp using such a supply.
Theory tells us that the efficiency of such an amp driven at its max is π/4~=78.5%.
This means that you need to supply 12.7W of average DC power input.
If, conveniently, your PSU has an output voltage of 12.7V, you will need 1A DC.
For such a supply & power, the load resistance is U²/P, U being the rms output voltage: 12.7/2√2, thus ~2Ω.

Spoiler

Now, if you compute the peak current going through the supply, it is 0.5*Vs/Rload, and 6.35/2 is 3.15A, thus more than three times the average current.

If you try to draw such a current at a low frequency (where most of the program power is concentrated), say 20Hz, your 12.7W supply is going to crumble twice per cycle, with disastrous audible results.

This example is simplified, and looks exaggerated, but reality can be even worse because of reactive currents.
I gave a class B example, but except for some class A, the problem is the same for all types of amplifiers, including class D: no amplifier has an energy storage capability (not enough for 20Hz anyway)

The problem arises because the supply's protection kicks in very quickly when dangerous levels are exceeded, which is normal for a regular supply.

You could think that adding energy storage, in the form of a large parallel cap for example could solve the problem. Not so: the regulation is extremely tight, meaning the internal resistance is small, and the capacitor would need to be really huge to make a difference, but much before that, it will cause problem during the start-up phase.

Audio supplies are designed taking into account these constraints, but if you use a regular supply in this role, it needs a severe derating: typically a 10W amp would need at least a 50W GP supply.

Note that if you use an insufficient supply, problems won't be noticeable at "normal" listening levels for "normal" music programs (not too much bass)"

Verdict:
If you want to take full advantage of the dual Merus in PBTL into 2ohms, you would need a regular ~600W PSU due to this rule. Continuus output (120W@2ohm@1%THD@26V) in watts times 5 (to ensure deep bass reproduction on all vol. levels). However, there are rarely any speakers that ever dip below 3ohm, so in reality the limit would be -25%=450W, which is really close to what the maximum output of the MA12070 in PTBL is anyway (432W@27V@16A).

 

[restorer-john]

And frankly replace the white thermal grease for a paste with a much higher rating. The standard white grease is in the super low 2's for heat rejection/absorption.

Dow Corning 340 or TC-5022 is as good as it gets. And yes, white and grey.

 

[milan616]

Verdict:
If you want to take full advantage of the dual Merus in PBTL into 2ohms, you would need a regular ~600W PSU due to this rule. Continuus output (120W@2ohm@1%THD@26V) in watts times 5 (to ensure deep bass reproduction on all vol. levels). However, there are rarely any speakers that ever dip below 3ohm, so in reality the limit would be -25%=450W, which is really close to what the maximum output of the MA12070 in PTBL is anyway (432W@27V@16A).

So what you're saying is I should hook up both my power supplies

 

[Moosi]

So what you're saying is I should hook up both my power supplies

I don't even know if that is possible with two single-volt-output PSUs. Even if it is, you would also double the amount of EMI those two produce. The Mornsun LOF-Series PSUs claim to be "medical", which might be true for the leakage current, but I took a deep nose into the EMI-rating-tables and was a little disappointed to see they are only certified "CISPR 32" for conducted&radiated EMI, which is a common "multimedia-rating" and thus not really hard to obtain. CISPR 32, Electromagnetic compatibility of multimedia equipment - Emission requirements (replaced CISPR 13 and CISPR 22)

I am currently planning on replacing my Mornsun with the faulty old relay with a Meanwell RPS-400-24 PSU, which is to be installed onto the same 5x3x1 frame into the case. There are several advantages those have:

1. CISPR 11, Industrial, scientific and medical (ISM) radio-frequency equipment - Electromagnetic disturbance characteristics - Limits and methods of measurement. (far better than CISPR 32 EMI-wise)
2. They are reported/tested @26.13V max. adjusted which is great for two reasons: a) I can run the Amp@near max. / b) having a PSU@max. lowers risk of coil whining on most PSUs.
3. Not only EMI, but also Ripple&Noise is supposed to be far superior to the Mornsun. However, the MA12070 can supress up to 70db ripple&noise generated by the PSU (again better than TP3255 that can only suppress 65db), so it may not be as much of an issue.
4. They can reach 250/470W short term before going into hiccup mode (200/385W@Mornsun LOF350).
5. They run a 5V/1A auxiliary out which operates at tremendously low ripple (~30mv/1A). Even lower than the best 5V/1A converter I have seen tested so far, which is the Apple Iphone adpator (~40mv/1A). This is great for plugging a 5V DAC to it, such as the Topping E30. You won't find a cleaner switching mode power source for your DAC than this (for people who don't like to use powerbanks f.e.).