Yes that is too much.
- Supply voltage: ±22V~±40V DC ±36.5V Type8A
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Just examined the board with integrated PSU but it looks fishy regarding cap quality and it is too cheap. MA5332MS looks to be a good class D chip but it is not a brother of MA12070 as it is not multilevel class D. It is more noisy too but also way higher in output power. Curious how it performs.
The simplicity of MA5332MS external circuitry and the multilevel of MA12070 combined would be nice so the wait is for a new MA120X0.
The simplicity of MA5332MS external circuitry and the multilevel of MA12070 combined would be nice so the wait is for a new MA120X0.
Took a look at the board of this MA5332MS implementation and compared it with the schematics in the Datasheet.
Noticed something strange at the feedback loop.
The Feedback resistor is not connected to the input of the MA5332 (as you would expect), but to the front of Rin, So between the Decoupling cap (other side) and Rin.
Double checked with the beeping multimeter.
Is this is a mistake? Do I oversee something?
Noticed something strange at the feedback loop.
The Feedback resistor is not connected to the input of the MA5332 (as you would expect), but to the front of Rin, So between the Decoupling cap (other side) and Rin.
Double checked with the beeping multimeter.
Is this is a mistake? Do I oversee something?
No.
10k from the NE5532 output to the decoupling cap. Then the Rin 2K7 where also the RFb connects to. Other side of Rin goes directly to the inverting input of the amp, with a small cap of the RC network shown in the simplified diagram.
The feedback of the MA5332MS is split, in first 1 small 1k resistor, then small cap to ground then 47k (Rfb in picture). Is this to allow smaller cap value?
Datasheet mentions: Gain = Rfb / Rin.
Then Gain should be 17,8. But it is not connected this way. We now have a feedback loop consisting of 1k + 47k + 2K7, where the input signal is coming in between de 47k and 2K7.
Noticed that the DAC playing at level 70 (80 being the max) is a bit loud, but I am still not blown away as you would expect.
DAC max output being at least 2V..
If Rfb was connected to the inverting input of the MA5332MS, then it would be all just the implementation of the inverting amp from the datasheet.
Rfb also determines the switching frequency, so you should change Rin to set the Gain.
Datasheet mentions decoupling cap should not be a ceramic.... because of distortion. This recommendation is neglected. Room for improvement.
10 kOhm at the output seems strange. Or is it a resistor to GND?
BTW when caps are used as DC blocker they are coupling caps. When they are used on power supply rails they are decoupling caps.
Probably something is overseen. I can’t judge when I am not holding a DMM myself. Maybe if you mention the part numbers something can be said. To me it seems the datasheet schematic with one extra resistor per channel.
BTW when caps are used as DC blocker they are coupling caps. When they are used on power supply rails they are decoupling caps.
Probably something is overseen. I can’t judge when I am not holding a DMM myself. Maybe if you mention the part numbers something can be said. To me it seems the datasheet schematic with one extra resistor per channel.
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Yes, of course. My mistake.
Yes, that is what I thought. Maybe 100 Ohm to protect output of opamp, but not 10K.
Would like to add pictures from the microscope camera, but can't get the images on screen. A stupid Windows thing. App needs allowance to use camera, but of course the app (and alternatives) don't show up in the list where you can set this allowance (privacy settings), and didn't find a clue on the internet....
If anybody knows how to solve this.... please tell me... (win 8.1)
Yes, except the feedback resistor connects to the wrong side of Rin.
Made a drawing of the circuit on this PCB. As I want to understand what is going on first, before thinking about changing anything...
MA5332MS card with power supply, ordered!
I will be able to put it in competition with my connected MA5332 amp.. https://www.diyaudio.com/community/threads/class-d-amp-photo-gallery.87913/page-105
wait and see !👍
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I have to correct myself. I should have looked one page further...
The implementation is an exact copy of the evaluation board. Except some values for the compensation.
If we have to see the 10k output at the opamp is also Rin, then the gain would be about 5 for the end stage. The pre stage having a Gain of 2, So together we have a Gain of about 10 for this Amp.
Not to good as reviewed in SMSL A300.
To high gain maybe?
https://www.audiosciencereview.com/forum/index.php?threads/smsl-a300-stereo-amplifier-review.46742/
Wondered if this is a bad implementation or if is this the chip itself?
Looked through the datasheet 3 times now for the channel separation. Couldn't find figures for the separation. For the MA12070 these are given.
Strange, left out the not so good figures? Normally this information you will find in any 2 or more chancel device....
Yes, plenty of power (and you hear that). In other thread (Sabaj A20) 84dB Speakers where mentioned. Guess best option is then to use these in 2 x mono setup. Gives you max 400W per side. Should driver difficult speakers properly.
In general the MA12070 clearly has better specs.
Stumbled over the MA2304DNS, when looking for more data. Looks interesting, except for the limited power capability of just 37W. Replaces the MA12040 (EOL) it seems.
Contains a DSP, Volume control, and a better DAC than the MA12070P (according to one of the designers). Specs closely behind the MA12070, at first sight.
This in a second generation MA12070P (for more power) would be very nice to make active speakers with it...
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Yes, either MA12070 with limited power and an army of ceramic caps but good numbers and good sound or wait for its newer incarnation.
Improving MA12070 ChiFi amplifiers is what I do but then they are not so cheap anymore. A totally self designed MA12070 design as we would like to see it with an army of film caps, good output filter, balanced buffer/balanced 4 channel volume control and linear 5A PSU will be an expensive amplifier with still low power
In dutch the saying is “hangen of wurgen”. To get hanged or to get strangled. Cruel expression but it makes it clear I think.
Improving MA12070 ChiFi amplifiers is what I do but then they are not so cheap anymore. A totally self designed MA12070 design as we would like to see it with an army of film caps, good output filter, balanced buffer/balanced 4 channel volume control and linear 5A PSU will be an expensive amplifier with still low power
In dutch the saying is “hangen of wurgen”. To get hanged or to get strangled. Cruel expression but it makes it clear I think.
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That is very interesting. Can we expect to see results?
Playing with the Sabaj showed that the MA12070 can deliver extremely good sound, very resolving. Heard things never heard before, and just so obviously there.... But everything in the chain must be optimal.
will be an expensive amplifier with still low power
Well, 70W is not that bad. Depends on which speakers you want to drive...
My old NAD 3155 (modded) is just 55W. But still like it. It is just so easy sounding. Compared, although very good sounding, also the MA12070 sounds a bit pushy. Just not that easy. Don't know how to exactly describe it.
Which will probably be just completely digital and/or face the same implementation issues...
MA12070
Noticed something when comparing datasheets.
On page 28 of the MA12070 datasheet, you can see that not all amps in the chip are equally good. PMP1 and PMP2 being much better in the higher frequencies.
Perhaps something to consider for the implementation?