General Guitar Gadgets TDA2030 amp

[Yazoo]

I've built the practice amp based on the TDA2030 chip from the schematic on the General Guitar Gadgets site. It works fine.

At the moment, I'm powering it from 2 9v batteries. The next step is to use the schematic for a bipolar power supply, again from General Guitar Gadgets. I'm going to build a 12v bipolar supply, mainly because I had problems getting hold of the 9v regulator chips.

I know the TDA2030 can take a variety of voltages. Will it be OK to simply substitute the 9v supply in the GGG schematic with the 12v supply?

I'm going to use a wall wart I have, which puts out 15v, 1Amp to feed the bipolar supply. What I can't find out is the amperage the bipolar supply expects. Will 1 amp be OK?

:?:

[Mark Hammer]

Two 9v batteries?!  I hope they were big ones.  Just sitting there doing nothing, the 2030 wants about 40ma.  Apply input and your best 9v alkalines shouldn't last more than an hour.

The TDA2030 can handle up to 36v single-ended or +/-18v bipolar.  The higher the voltage, the greater the output in wattage.  Wattage also implies current, however.  Just as importantly, wattage is a function of load impedance too., and not all watts are created equal.  Though a 2030-based amp CAN be urged to deliver, say, 10 watts of power into an 8 ohm load with a +/-12v supply, those will not be 10 *clean* watts.  The datasheet indicates a distortion level of 0.5% with 5W delivered to 8 ohms with a +/-12v supply.  More wattage can be enticed if the input signal is hot, but it will not likely get much cleaner.  You may SAY you don't care because you want some distortion anyways, but the TDA2030 is not designed to break up pleasingly, the way other stages are.  So, best to extract the distortion from other stages than the power amp chip.

A one amp supply ought to be more than sufficient for many duties and should give you at least a couple of "clean" watts.  You may feel, like many, that you'd prefer to extract more wattage, but rest assured that even 5 watts is PLENTY loud.  I'm running a little LM380-based amp on a 6" speaker from 8 C-cells and it can easily coax feedback from my pickups.  Typically, a tenfold increase in wattage is required for the same speaker/cab/signal combination to be heard as *twice* as loud.  What that means is that you wouldn't be able to hear a whole lot of difference between 5W and 12W in your amp.  A much greater difference in loudness will be achieved by selection of a more efficient speaker in a decent cabinet that conserves and projects air.

All that being said, you may find the need to increase the value of the 680R resistor a bit (e.g., 1k) just to keep the gain sensible and not tax your transformer.