Tda1524a

[epilot]

Hello,

I want to make the bellow tone control circuit based on TDA1524A chip.
The power supply would be between 16 TO 18V.
http://www.aaroncake.net/circuits/tone.asp
Here is the data sheet for the chip too:
http://www.datasheetcatalog.com/datasheets_pdf/T/D/A/1/TDA1524A.shtml
**broken link removed**

It would be made for a mono amplifier, so I'll eliminate the components for one Channel.
Well, as the chip is a preamplifier too, so I need to know if the circuit is ok with a dynamic mic too, or I need to modify it as a preamplifier for the mic?

If it is ok to do so, I want to know if it can do the job even when the bass and treble are closed to?

 

[audioguru]

The tone controls IC has a max voltage gain of only 20. A dynamic mic needs a voltage gain of about 400. Of course the mic needs to have a preamp and its gain needs to be 20 to 50.

 

[epilot]

The tone controls IC has a max voltage gain of only 20. A dynamic mic needs a voltage gain of about 400. Of course the mic needs to have a preamp and its gain needs to be 20 to 50.

Many thanks audioguru,

So, as I want to use a fair mic preamplifier, what is your idea about the below dynamic mic preamplifier?

**broken link removed**

 

[audioguru]

That preamp shows BC547 ordinary transistors that have a very wide range of spec's. I would use BC549B transistors that are low noise and are selected with "B" spec's.
The distortion wasn't measured. I would add a bootstrap capacitor and resistor to it to reduce distortion.

 

[Nigel Goodwin]

I wouldn't have thought bootstraping would make much difference?, you're not looking for massively high output levels from it, and it's already a pretty reasonable double transistor stage with lots of negative feedback.

Be interesting to see what simulation says about distortion with and without bootstraping?.

 

[audioguru]

I wouldn't have thought bootstraping would make much difference?, you're not looking for massively high output levels from it, and it's already a pretty reasonable double transistor stage with lots of negative feedback.

Be interesting to see what simulation says about distortion with and without bootstraping?.

An amplifier design site has nearly the same two-transistors output circuit. It has a gain of only 3 but the distortion with bootstrapping is 10 times lower. **broken link removed**

I made the sim and the gain increases and the distortion decreases at high levels with bootstrapping. The 2.2k emitter resistor for the 2nd transistor has a hard time trying to pull down the bootstrap resistors and works much better as 470 ohms (I didn't change it in my sim).

 

[audioguru]

Here is the circuit with very low distortion because it has bootstrapping and the value of the 2nd emitter resistor is reduced.