18 August 2008

MAKE or BUY GUITAR AMPLIFIER ?

MAKE or BUY GUITAR AMPLIFIER ?


After buying an electric guitar, for about 1 month can not enjoy this guitar, I am just be amazed holding and touching it, why ?, because I do not have an amplifier.

Buy ? the price starts from US$ 40 for locally made, unfortunately box dimension is rather big, and the appearance is not attractive, I just want a small dimension, but as it was quite expensive, say brands like Roland Cube, Peavey, Bosch, Ibanez etc.. also a top brands like Polytone Minibrute.




Another alternative is to use an computer's active speaker. After trying brands such as Altec Lansing, Creative, etc.., sound is too weak and very very bad, as if it is covered or muffled, not suitable for an electric guitar at all !.

Ok, the last alternative is to make my own amplifier. I already have a speaker in my junk box, it is from my former office sound system, specifications is a full range speaker, not for woofer or subwoofer.

For amplifiers, the common criteria I need is: simple, flat frequency response, output power sufficiently to be played in a room alone.

TBA810 AUDIO AMPLIFIER IC
The results of my choice is TBA810 IC, the specifications:
5M ohm input impedance as high as I expected, sensitivity is high so there should be no pre-amp, power supply voltage range of 4 to 20V, the output power 7 Watt, just try to make it and see how good is the result.

Here is the scheme. No need to make a pcb, use ugly construction, quickly becomes.

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How is the sound produced? Quite satisfactory, clear, bass and treble flat and fitted played alone in the bedroom. My suggestion for a speaker, box made is ​​absolute.
To reinforce the bass, the speakers can be placed under the table or under the bed.


LM1875 HIGH PERFORMANCE AUDIO AMPLIFIER IC

Now I want a bigger power, amplifier criteria same as above, simple, not a lot of components, and has a good voice. I tried searching on google with keywords STK15 IC, but this types of IC are apparently outdated.

Now there are ICs that much smaller in size, but more powerful abilities.
Election falls on the type of IC LM1875, specifications 20W output, supply voltage from 16V to 60V (for double power supply V + = 30V and V-= 30V maximum), 30W max output depending on supply voltage, low distortion.

For this amplifier, is inverted design, scheme, construction, and powersupply as follows:







For this amplifier it is required a pre amplifier, designed with three input (or more) and respectively - each have a volume control as follows: L-MP3 player, R-MP3 player and guitar itself.

If you have MP3 songs to practice ( minus one song ), say the left channel for rhythm, the right channel for the melody, one of the lines can be diminished, (without disturbing the volume of the other lines).

Pre amplifier schematic as follows :


Everything is assembled in ugly construction method, a note for pre amplifier: try input cable is quite short, check that the grounding should be the one with the amplifier circuit and the circuit power suplly, otherwise it will sound drone. Keep the pre-amplifier input of the power supply transformer, or give them grounded screen.

Now how is the sound of this amplifier?
Very impressive !!!.

You have to make it yourself to be able to feel it.

Here is the layout and images - pictures:





MODIFICATION

After a while, potensio volume control tend to be dirty and crackle noise make it difficult to fit the desired volume. I modified it with a 3-position switch: on-off-on or half volume, mute, and volume up, as follows: