Yes I have balanced preamp.
20 till 30Watt is enough, I need it for 108db tweeter.
Now using 8 x parallel LME49600 with OPA1611 composit.
Next build should outperform this one on distorsion and noise(0.000088%/1W/8ohm)
20 till 30Watt is enough, I need it for 108db tweeter.
Now using 8 x parallel LME49600 with OPA1611 composit.
Next build should outperform this one on distorsion and noise(0.000088%/1W/8ohm)
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Yeahhhh, not aplicable for the tweeter 😁 Bass/mid bass can be hungry, not the tweeter though. Thats why you sometimes see 1-2W SE tube amps, wired for tweeters.
Can hardly call it a regular tweeter with 1k-21k freq res 😁 Certainly a niche product. I'd skip this amp if you require 30W in class A.
I assume if you need more power you can :
1. Use opamp that accepts higher PS voltage like OPA604, with some cost at THD performance. Then +-22V could be applied but they must be regulated as mains peaks could still fry opamp at such close tolerance to max V PS.
2. Use sziklai pair at output instead of mosfets, but than you need to introduce biasing with thermal compensation and it is not this amp any more.
With both above mods , close to 20W @8Ohm should be achievable, but as I said, then it is similar but different amp....
I think you should try the Sioux amp. I ordered a PCB yesterday. I will build a prototype and check it within 2 weeks. If everything is OK, I will add Gerber files and I will have several PCBs
If more power is needed you can try this amp:
LatFet Amp Based on Philips AH578
https://www.diyaudio.com/community/threads/latfet-amp-based-on-philips-ah578.367494/
OPA604 is not a good option.
My simulation shows it has low headroom.
Hmmm, I never did it for this purpose but have seen few recommendations for its high PS voltage acceptance. Nevertheless I used OPA2604 and think that it is not the best chip really, Sound is actually chip-ish 🙂
Probably nobody checked what is headroom regardless of PS ...
This is from OPA604 datasheet:
It suggests that opamp is losing 3 volts from its + and - PS rails (+-15 VPS = 30V p-p, graph is flat at 24V p-p) .
If we give it +- 22V PS- 3V - 1V (for sziklai pair) that equals 18Vx2 peak to peak, divide by sqrt2 and 8 ohm, result is just above 20W as I mentioned.
Nevertheless I trust you when you measured it, and don't regret at all, it is not best OPAMP anyway. Good for me to know it doesn't perform in headroom region as I had remote plans to use it for background music amps (diagram as your Choctaw).
However, there must be some opamp that can do about 18V p-p, I just don't know them....
Tested today my build.
First there was a fault with reversed pin 2 and 3 of the OPA1611.
Changed the schematic and build.
Now it takes more then 6 amp from the power supply en this shut down.
@lineup or others that can help, must I change(higher)R5/R8 to compensate for the supply change(16 to 24V)?
To get the right setting for the Fets.
First there was a fault with reversed pin 2 and 3 of the OPA1611.
Changed the schematic and build.
Now it takes more then 6 amp from the power supply en this shut down.
@lineup or others that can help, must I change(higher)R5/R8 to compensate for the supply change(16 to 24V)?
To get the right setting for the Fets.