1# NE5532 - nothing wrong with them
Voltwide showed THD performance for genuine TI NE5532 in a test setup as so:
2# OPA1602
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You're on your own there, once subjective the sky's the limit and opamp rollers will have their field day.
Not sure exactly how they set up the circuit around the input buffer (I'm assuming evm scoop so inverting?), but if it's noninverting, I'd probably try the DI-process 1642 in that location as to mitigate any common-mode distortion. Gonna need a DIP8 to SOIC adapter, but those are easy to find. Noninverting? An authentic NE5532 is hard to beat, OPA2209 wouldn't be too shabby either, with similar distortion to the latter, but lower noise (current and voltage).
Not sure exactly how they set up the circuit around the input buffer (I'm assuming evm scoop so inverting?), but if it's noninverting, I'd probably try the DI-process 1642 in that location as to mitigate any common-mode distortion. Gonna need a DIP8 to SOIC adapter, but those are easy to find. Noninverting? An authentic NE5532 is hard to beat, OPA2209 wouldn't be too shabby either, with similar distortion to the latter, but lower noise (current and voltage).
ICG
Yes, the piece was a bit of a hit job but as far as I know the fundamental characteristics they emphasized about class D in general still remain. I own a set of cheap class D amps that I intend to experiment with. The loads they are able to handle makes them attractive and there is a place for them in hifi but I just don't think it's in the top sphere yet. The ten years you reference have also advanced the class A and B spaces. The IMD numbers coming out of those latest designs were not commonplace 10 years ago.
Yes, the piece was a bit of a hit job but as far as I know the fundamental characteristics they emphasized about class D in general still remain. I own a set of cheap class D amps that I intend to experiment with. The loads they are able to handle makes them attractive and there is a place for them in hifi but I just don't think it's in the top sphere yet. The ten years you reference have also advanced the class A and B spaces. The IMD numbers coming out of those latest designs were not commonplace 10 years ago.
A bit old web page but some op-amps is still available Notes on Audio Op-Amps
Scroll down a bit to read the authors verdict of different amps. Would be interesting to try and replace the NE5532 with some of those, but it has to be a dual package.
Oh really? Which developments took place in the last 10 years in class A/B? There are amps from the 90s which already got 5 digits after the decimal point, not really any actual improvement needed there. Let's face it: The improvements on class D were so much bigger steps than the development in class A/B in the last 20 years. There's nothing wrong with A/B and with the extended time it's been around, there aren't much developments to be expected anyway. To compare the generations makes much more sense though and there you should start, comparing the latest generation and, to be fair, stay in the same price region.
ICG
The understanding and implementations of pole compensation were all developed on Class A/B in the last 20 years. Ditto for their exploitation in the composite amp topology. Class D benefitted greatly from these advances in Class A/B. Show me some amps from 20 years ago that had <5ppm IMD at rated power with acceptable harmonic profiles. Hell, show me some from 10 years ago if it makes your day.
The understanding and implementations of pole compensation were all developed on Class A/B in the last 20 years. Ditto for their exploitation in the composite amp topology. Class D benefitted greatly from these advances in Class A/B. Show me some amps from 20 years ago that had <5ppm IMD at rated power with acceptable harmonic profiles. Hell, show me some from 10 years ago if it makes your day.
While that is an improvement in some areas, it's a loss in others. It strongly depends on what the goals are and to improve already inaudible THD at the expense of the slew rate isn't a step forward in every case. And to be more precise, pole compensation isn't an achievement of class A/B, it's an achievement/development of any amplifier. And to be more precise on that (again), that was shown not on A/B amplifiers, instead it was demonstrated on OP amplifiers and can potentially applied to most amplifier classes.
See, extreme numbers are very good for brochure specs and sales but it's not a revolution in amplifier design. If it was, you'd see every new amp following that - which isn't the case, it's still a weighting of the importance of dis-/advantages. So if, in any case, it was a step forward (which I don't want to doubt or discuss here), it is for all amps and not something A/B brought up.
See, extreme numbers are very good for brochure specs and sales but it's not a revolution in amplifier design. If it was, you'd see every new amp following that - which isn't the case, it's still a weighting of the importance of dis-/advantages. So if, in any case, it was a step forward (which I don't want to doubt or discuss here), it is for all amps and not something A/B brought up.
How much is actually needed depends on the use and the amplifier topology. Aber das wußtest Du ja sowieso.
Got them in house just now.
I will not comment on general sound quality just yet. But compared to the 4-5 different tpa3116's I have heard, the tpa3250 is in a different league. Bass is MUCH better defined. I think it will be interesting to try it up against the folsom tda7297.
I managed to get the error lamp blinking, played some loud reggae, right channel just cut during a peak, left kept playing on. Reset the amp and everything is well again. It seems something happens if the in-level is a touch too high and the amp pot-meter is a bit high also, just a click or two down the volume on my phone and max volume is no problem. There might be some gentle compression but I may be imagining things. Transients are pretty good.
I will not comment on general sound quality just yet. But compared to the 4-5 different tpa3116's I have heard, the tpa3250 is in a different league. Bass is MUCH better defined. I think it will be interesting to try it up against the folsom tda7297.
I managed to get the error lamp blinking, played some loud reggae, right channel just cut during a peak, left kept playing on. Reset the amp and everything is well again. It seems something happens if the in-level is a touch too high and the amp pot-meter is a bit high also, just a click or two down the volume on my phone and max volume is no problem. There might be some gentle compression but I may be imagining things. Transients are pretty good.
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Maybe your power rail isn't stiff enough, so it collapses just enough to hit OCP threshold. Pretty much sounds like that because OCP is only shutting down the affected halfbridges.
I.e. consider an overall impedance/DCR from power supply to amp of 250mR and a 6A current peak. Rails collapse by 6*6*0.25 = 9V already. This easily triggers OCP
I.e. consider an overall impedance/DCR from power supply to amp of 250mR and a 6A current peak. Rails collapse by 6*6*0.25 = 9V already. This easily triggers OCP
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Yes, I think that's the thing.
Was considering hooking them up with my big speakers to give it a go, but from what I've seen so far they will just replace all my TPA3116's in house and I'll be very happy with the upgrade.
Will look for some plugs that fit, to see if it gets better with 2x12v. If not then it's the smoothing stuff inside that gives up.
Very low noise though! And there really is no comparison to the 3116. Build quality is "good enough"( as in very good for the money, but not "The End"), I like the feel of the volume knob, a bit like stepped attennuators with "notches", but think it's just a potmeter.
Was considering hooking them up with my big speakers to give it a go, but from what I've seen so far they will just replace all my TPA3116's in house and I'll be very happy with the upgrade.
Will look for some plugs that fit, to see if it gets better with 2x12v. If not then it's the smoothing stuff inside that gives up.
Very low noise though! And there really is no comparison to the 3116. Build quality is "good enough"( as in very good for the money, but not "The End"), I like the feel of the volume knob, a bit like stepped attennuators with "notches", but think it's just a potmeter.
3250 Impressions
Running source content through ,Yamaha wx50 pre ,streaming pandora and tidal to 3250 to Pensils ,nearfield--- The sound was very good low to mids . Volume pot was very very sensitive . After I listened for a couple of hours, moved it to wifes office tv [ replaced a Lepai 2020] and she said , thanks, sounds good. WAF . I was hoping for a D amp to get me interested in amp building, modding, whatever. Maybe. This old man loves music, for my ears, good sound as described.
Running source content through ,Yamaha wx50 pre ,streaming pandora and tidal to 3250 to Pensils ,nearfield--- The sound was very good low to mids . Volume pot was very very sensitive . After I listened for a couple of hours, moved it to wifes office tv [ replaced a Lepai 2020] and she said , thanks, sounds good. WAF . I was hoping for a D amp to get me interested in amp building, modding, whatever. Maybe. This old man loves music, for my ears, good sound as described.
Great review, that is FX502S-Pro implementation of tpa3250, yah?
FX502S-Pro config tpa3250 as a 2.0 BTL. Anyone has any idea how to config FX502S-Pro to become PBTL monoblock?