LM3886 as Tweeter high pass amplifier.

[Hayk]

Now I have a simple 2nd order 2khz high passed amplifier.
The 100M resistor is for the simulator. The cut frequency is inversly proportional to 2.7nfx2 capacitors. The Q is adjusted by the feedback resistor 100k.

 

[Hayk]

This is the 3rd order.

 

[Hayk]

I could make the OLG equalized version also Slew Rate Limited. Unfortunately, it needs an input buffer to add a high pass filter which in turn will require another buffer. I will not use it as self filtered.
I must listen first if it does have a good midrange sound as the 3886 has naturally in tweeters. Then, if I succeed to sound it full range by high temperature, it will become a beautiful sounding amp with presence adjust and sweet tube sounding option.
If not, I, will add an adjustable current feedback to make the output Z variable to 8 ohms with R6=0.025 ohm. It can be suitable for open back speakers or guitar amps.
As it is no more a tweeter amp, I will start a new thread for it.

 

[Hayk]

I would not spend too much time on this. It's symmetrical, so it sounds like a push-pull tube amp, not single-ended, no even harmonis. Plus, the most important part, there's no way of getting soft clipping like in tube's VI curve. So this design will probably become a combination of all the bad things from the tube and solid state amps

I was impressed by this comment, how this fabulous amp can give bad impression. For that, I suppressed the SRL option to leave only clean amplifier with inherent high pass filter. I added the input jfet buffer to be independent from source impedance.
For the SRL option, I will add on the OLG corrected version.
I found a way to erase the thermal feedback, maybe it can work. The mute pin has 3 diodes voltage drop from ground level, so the temperature variations inside the chip are reflected at this pin 8. I can harvest it and subtract from the either inputs.

 

[Redacted]

I may be wrong, but I have heard that most recent solid state guitar amps are using class-D designs, as more players go to DSP pedals and sims, and are using FRFR amps. I'm still happy with my Blackstar valve hybrid though!

 

[Hayk]

Portable battery operated guitar amps are all classD. The open back speakers need adjustable damping factor. Eminence does have speakers that the magnetic field is adjustable but others need the amp to do be able to. With analog amps is very simple whereas with classD ones not easy to stabilize.

 

[Redacted]

I think most mains ones are, like the Positive Grid ones, and all the Chinese brands.
Battery OK for home practise, but not for live or jamming with friends.

 

[Hayk]

I got banned from engineering discussions on this website, this thread is discontinued.

 

[Power Pop 23]

Per Amir,

4 transistor class A very low THD 40w amp.

I have designed long ago, a type of SRPP MOSFET output amplifier, that has ended after several models to https://www.eevblog.com/forum/projects/4-transistor-40w-class-a-0-0004-thd-amplifier/ How it works. The Q1,Q2,Q4 don't need explanation. Q3 is biased by a voltage across 470uf capacitor Vc...

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