TDA7293, exempt of crossover distortion.

[KL....]

TDA7293 is a mosfet chip.

Thank you, Yes, hybrid design with Bipolar input stage and MOSFET output stage?

2.5v/us is good for 20w, but when bridged it will double, then good for 80w 8 ohms or 160w 4ohms.

2x Slaves.... 5v/us, 80w 8 ohms or 160w 4ohms?
3x Slaves.... 10v/us, 160w 8 ohms or 320w 4ohms?
4x Slaves.... 20v/us, 320w 8 ohms or 640w 4ohms?

 

[Hayk]

Wrong.
Deal with the Chinese TDA2050-LM1875 only if you need very very low cost 200w amp.

 

[KL....]

2 slaves bridged 5v/us
2000000 slaves bridged 5v/us
Deal with the Chinese TDA2050-LM1875 only if you need very very low cost 200w amp.

Thank you, Yes, there should now be (here) more than enough information for others to discuss with you.... Quite Novel, thank you for shareing, appreciated :=)

 

[Hayk]

I noticed that DIYs aren't interested in low power amplifier. After all, the TPA3110 in ABD modulation with 2x30w@4 ohms is unbeatable for SQ, costing less than $25.
To save my innovation of transforming class AB into class A type exempt of crossover distortion, I made the TDA7293x6 in differential, single 48v supply to pour 250w@4 ohm.
It works with 2 masters, on PCB and 4 slaves on heatsink. It can be single ended input or differential. The size of the PCB will be 100x75mm to cost $4/5pcs
To start with, I will keep as simple as possible to check for sound quality and add extra components if needed, as Jfet input buffers for example.
All components are standard THT for low cost and DIY friendly.

 

[Hayk]

It looks much easier than I thought. 100x53mm and some extra space. Thiel LR or speaker protection?

 

[Hayk]

Optional speaker protection is added, the empty space on board is sufficient for connectors. The Thiel LR and Zobel if needed, to be installed at the output speaker connector.

 

[Hayk]

On Ali, there is a trustworthy shop that provides me genuine components.

Qslmk Store-AliExpress

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m.aliexpress.com

The shipment is not so cheap but quality package and relatively fast.
6 months ago, I bought TDA7293 for $3.6 a piece, now $2.21.

 

[Hayk]

I have received the PCB that I will try it out next month. It has some errors to be corrected but functional.
Besides, I have designed a simpler one with single ended output that receives multiple add on boards for the input stage making it error corrected, composite or tube sound simulation.
I will redo this amp only with the tube sound simulation. It has optional speaker protection.
I replaced the 2n7000 with 2sk170. The Chinese replica of this jfet is excellent. It cleans the nonlinearties of the chip and staines the sound with its own.

 

[Hayk]

I made it as simple as possible to incite building it. The speaker protector will be seperate board attached to be used optional or cut off, maybe used separately for other project. I must find a way to cheat the manufacturer to make him convince the 2 circuits are one, or else it will cost more.
It runs with +/-28v to deliver 40w@8 ohm and 70w@4ohm.

 

[Hayk]

I will add error corrector board optional on the high power PCB.
It comes attached to the PCB to seperate and plug in or not.
I simulated using lm324 opamp to show how the EC works, without 0.02% THD with 0.0008%.

 

[audio_tony]

I will add error corrector board optional on the high power PCB.
It comes attached to the PCB to seperate and plug in or not.
I simulated using lm324 opamp to show how the EC works, without 0.02% THD with 0.0008%.

I'm confused. Apart from C1 (which appears to be 0uF) in the first schematic and 10uF in the second schematic - is that the only difference?

 

[Hayk]

It conveys via the capacitor. With 0 uf it disables the convey from - input to +input.
You can see bellow how the error ac voltage on the negative input decreases as it get conveyed to the positive. By this the out/in =-22k/1k is more precise.

 

[Hayk]

PCB with detachable EC board.

 

[Hayk]

The composite 2x7293 version modified.
I input jfet provides 200 times correction to the chip and replaces by its own nonlinearty. The second 7293 was erasing non significant crossover distortion.
I shorted its linking capacitor so that it participates to the output power in modular form. Now my amp is twice the power to be 70w@8 and 140w@4.
I modified the PCB to install bigger capacitors and wider tracks.
The power supply is +/-35v.

 

[Hayk]

The 2x3 7293 board is not good for 250w amp. The output track are thin and cannot be wider. I needed to add offset adjust, the performance is depending upon source impedance. I returned back to the initial circuit with crossover distortion eraser to be used without error corrector, or else it doesn't make sense. I added on each input a low noise jfet, and as I had space left, I added a SSR speaker protection.
The board is 100x87mm.