I'm currently working on a 3 way active speaker. The low end power amp is going to be powered by TPA3255. As for the mid and the tweeter, I figured since it's not that much power to maybe just go class A for each of them. Looking for any design advice (yes I know there's a lot out there, but asking never hurts... except when someone throws a brick). I'm thinking of using GaN for the output stage, but I've read mixed reviews. I've also read transformer coupling can increase efficiency, but also has its own drawbacks. Hell, maybe I could just keep it simple... nah 🤣
50W class A will generate a lot of heat. Use some moderately efficient drivers and 10W per driver would likely be plenty.
Have you seen this project?
https://www.diyaudio.com/community/...te-low-power-class-a-amplifier-my-way.404147/
Have you seen this project?
https://www.diyaudio.com/community/...te-low-power-class-a-amplifier-my-way.404147/
I haven't seen an example of a GAN FET used outside of a class D amplifier. As said above, 50W class A is a lot no matter the output transistors.
That looks promising. Might have to snag an idea or 2.
Ok so a little background: initially the whole design was supposed to be 50W total. However, the speaker sensitivity of my low-end speaker is about 10db off from my mid and hi end. That's why I'm using such a high power chip amp for the low end. I'm trying to compensate for the loss.
I definitely have been considering dropping the overall power. I'll admit I've been rather paranoid about underdriving things...
Also, IGBTs yay or nay? Was reading https://www.diyaudio.com/community/threads/igbt-amplifiers.97551/ and makes a compelling argument for them. However, not sure if they have any that are lower power out there.
Also, IGBTs yay or nay? Was reading https://www.diyaudio.com/community/threads/igbt-amplifiers.97551/ and makes a compelling argument for them. However, not sure if they have any that are lower power out there.
RF amplifiers (my day job). Their linearity leaves a lot to be desired, though. Fine for tuned circuits or if digital correction is available. I wouldn’t mess with them for audio. And class D isn’t audio - it’s switching.
Ironic because in another life I worked on radar. Maybe I should just switch to class D lol
H
HAYK
I have numerous classA amps including 2 stage 50W. I have 300B SET to power 105db speaker. The highest resolution amp I got is the $1 costing TPA3110, excellent to reveal the qualities of your super tweeters. Second comes the TDA7498e board $12 much higher quality than lm3886. On condition that these amps are converted into ABD mod.
Post in thread 'Convert your class D into ABD modulation' https://www.diyaudio.com/community/...ass-d-into-abd-modulation.396664/post-7290300
Post in thread 'Convert your class D into ABD modulation' https://www.diyaudio.com/community/...ass-d-into-abd-modulation.396664/post-7291117
Post in thread 'Convert your class D into ABD modulation' https://www.diyaudio.com/community/...ass-d-into-abd-modulation.396664/post-7290300
Post in thread 'Convert your class D into ABD modulation' https://www.diyaudio.com/community/...ass-d-into-abd-modulation.396664/post-7291117
I actually would not mind implementing a design like that. Originally I wanted to do dsp right into something like a TAS6424, but I'm just not a very strong coder and not as boned up on digital design as I am analog.
Don't overlook TPA3255. It can beat most of amplifiers out there. I doubt a hand made Class A is any better than a well implemented Class D.
https://www.audiosciencereview.com/forum/index.php?threads/fosi-audio-v3-amplifier-review.45757/
https://www.audiosciencereview.com/forum/index.php?threads/fosi-audio-v3-amplifier-review.45757/
You're using the Dayton 5.5" for your low end? That's 83dB at 2W (2.83V/4 ohm). Are your other two drivers 8 or 4 ohm? If they're 4 ohm, then 50W would give you the 10dB difference, but if 8 ohm, 25W would do it. [Using the TPA3255 255W 1% 1kHz THD spec].
Good point. I was looking at them recently with a linear AF purpose in mind but couldn't find any SPICE models or much useful info in datasheets for the purpose. Ended up gaining a bit of an understanding of class F in the process however.
Ironic you should say that because that's one I've had my eye on for a while lol. I was initially going to use it for the sub because it can provide enough power. Although if I scale everything back a bit then it shouldn't be an issue. I just have to dig into the spec sheet a little further to see if I can run it that low...
A little while ago I got a deal on a pair of KEF SB1632s. That's kind of what kicked off this whole thing.
In other news: since you guys suggested scaling back I decided to look in headphone amps to maybe make a hybrid solution. I found one I completely overlooked because I thought the company that makes it only made good DAC chips. https://www.esstech.com/wp-content/uploads/2022/09/SABRE9601K-Datasheet-v1.6.pdf Thoughts?
The models are all RF/microwave, usually for harmonic balance (or some derivative of it). These damn things have charge trapping issues, which make Spice a near impossibility. And it messes with linearity….
Most of them HATE class F operation. Inverse-F (also called class E) and they are fat and happy.
Also, while I'm here, I may as well ask: what's the validity of weird/proprietary designs like G/H, XD and T amplifiers?
They are all about efficiency. In between class D and AB efficiency, but a MUCH easier design problem when high average power is used. Class D amplifiers don‘t scale up to the multi-kilowatt levels without introducing sound-quality-destroying timing problems. Class G, H, etc. do. It will never be as good as the best class AB, but getting the usual .05% THD out of class H is relatively easy no matter how big you build it.
I do like power efficiency... means less I have to put on my electric bill
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Doesn't class G and H also require a switching supply? I thought that was a nono in audio applications other than highly integrated ones? Also what limits them from achieving the same THD?
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Doesn't class G and H also require a switching supply? I thought that was a nono in audio applications other than highly integrated ones? Also what limits them from achieving the same THD?
G and H can be built with standard power supplies - just need high and low voltages. The big stuff uses three or four (on each side) to keep Vce down under all conditions. I’ve prototyped up to about 2kW…. And down to about 100. It was a cute little amplifier board.
You do get the same distortion as AB at low listening levels. But you also get a type of crossover distortion that you cannot remove, but in practical use, can’t hear. But it’s there. Audiophiles will never accept it because it IS there. It happens at the voltage transitions, where it is effectively masked by the music.
You do get the same distortion as AB at low listening levels. But you also get a type of crossover distortion that you cannot remove, but in practical use, can’t hear. But it’s there. Audiophiles will never accept it because it IS there. It happens at the voltage transitions, where it is effectively masked by the music.
It's funny you should mention this. That's something I'm working on in my preamp. I'm trying to figure out a way to use a precision ZCD to trigger an all-pass filter to add just the right amount of delay at the moment of crossover. What causes the crossover distortion?