12V DC Power Supplies and Amps

Thread Starter

Dolmetscher007

Joined Mar 21, 2019
36
I ordered a very simple Guitar Amplifier PCB kit. It's a TDA2030 Audio Amplifier, a TL071 JFET-input op amp, with a bunch of caps and resistors.

I soldered everything up, and I was reading the online instructions. This is the kit, by the way. In the Description of this kit, it says the following about Power Supply:

The operating voltage is 12vdc. It has two 1000uF Capacitors on the input power for additional filtering. You will need a 12vdc power supply capable of delivering at least 2 amps, a 20-watt or better power supply will work just fine.

I was going to buy a new "wall wart" 12V power supply on Amazon, but then I remembered that I already have a "laptop style" 12V power supply that I bought to power a big LED project a few years ago. This power supply says...

Input: 100 - 240VAC - 50/60 Hz, 2.7A
Output: 12V === 10000mA

This may all be perfectly obvious to you guys... but... will a power supply that has an output of 10000mA safely power a circuit that needs a power supply, "capable of delivering at least 2 amps?" First off... 10000 mA is 10 Amps... right? Is the idea that this power supply can deliver "up to 10 Amps"... but this little amp circuit will only "draw" what it needs?
 

bertus

Joined Apr 5, 2008
22,119
Hello,

Yes, you are right. The amplifier will take the current it needs, no matter how much the powersupply can deliver.
It can be the choosen power supplt is a switch mode type.
This could give some noise for audio systems.

Bertus
 

Audioguru again

Joined Oct 21, 2019
5,413
The minimum power supply voltage for the obsolete TDA2030 amplifier IC was 12V. With a 28V supply its stereo output power was 14W per channel into 4 ohms or 9W per channel into 8 ohms.

Aren't guitar amplifiers mono, not stereo? Since the TDA2030 amplifier is stereo then I think its two channels are bridged into mono then it might produce 2.6W into 8 ohms plus 3.9W of heating.
When bridged, a 4 ohms speaker might overload it, or produce an output power of 5W plus heating of 8W for a total power of 13W. Then the 12V power supply must deliver 1.1A.
 

LowQCab

Joined Nov 6, 2012
2,627
I think that in any case You will not be very satisfied with this Amplifier
when using it for Electric-Guitar.

A Solid-State, High-Fidelity-Amplifier, will be just fine for Electric-Guitar as
long as You have at least twice the power that You think You will ever need.
When pushing a Solid-State-Amplifier into Clipping-Distortion with a Guitar
the result is very harsh and sounds REALLY BAD.

As long as any Distortion that You may want comes from either a
Software-Package installed on a Computer,
which is designed specifically to emulate Guitar-Amplifier-Tube-Distortion,
or from actual Guitar-Effects-Boxes,
everything will work just fine with a Solid-State-Amp, and High-Fidelity-Speakers,
as long as You NEVER run the Solid-State-Amp into Clipping-Distortion.

The Amp that You have bought will not provide enough
Power without going into Clipping-Distortion,
regardless of what You do with the Power-Supply.

Here is a suggestion for an Amp that will do whatever You want,
as far as "practice" goes, with a small High-Fidelity-Speaker.

This Amplifier will provide enough Power for a small "Live-Gig", depending on the Speakers used.

https://www.parts-express.com/FX-Audio-FX-502A-PRO-Hi-Fi-Stereo-Amplifier-50-WPC-Black-230-279

If You'd like to build your own Guitar-Speaker/Cabinet I can provide You with plenty of options
to suit what ever environment You might be playing in.
.
.
.
 

MisterBill2

Joined Jan 23, 2018
13,709
From the data sheet, the TDA 2030 is a single channel amplifier. But IF the kit is a stereo amplifier then you can operate the system in a bridge configuration and easily get 28 watts, at least. Others may complain about that, but certainly it has been done and it can work well.
As for being satisfied, that depends on what sort of music you want to produce. All of the modifications to the sound will need to come from external modules, which allows you to do as much as you can afford to do.
AND, using a ten amp supply is a good way to assure that your system will not be straining with a supply running at it's maximum capability. So the tan amp supply is a good choice.
 

Ya’akov

Joined Jan 27, 2019
6,854
Welcome to AAC.

As @bertus said, you are correct about the behavior of the circuit and supply. In a very limited analogy, imagine the amplifier being powered by water. The voltage is like the pressure, it will be a constant and if it is too much it will damage the amp by forcing it to consume too much current. The current is like the volume of water, so long as the pressure is right the volume will be self regulating.

Analogies for electricity are fraught. They break down very quickly—keep that in mind. But this one can be a useful way to remember the relationship of voltage and current at a very high level. It an extend a little bit, but dont assume any understanding you have about the behavior of water will tell you someoitng about electricity. The need for this long disclaimer almost makes the analogy not worth the trouble, almost, but not quite.
 

MisterBill2

Joined Jan 23, 2018
13,709
Indeed!! With only five leads to the device it can only be mono. Using two of them in a bridge mode is common and works fairly well if it is done correctly.
I think that it is Peavey that actually made a "practice" amplifier using that device. But it was a keyboard amp, not a guitar amp. That device was not obsolete at the time. And my recollection might be off a bit.
 
Top