I present to the masters my development of the amplifier on the TDA 7294 chip. I want to inform you right away that I did not invest almost a dime in the project, with the exception of two resistors and two sockets for tulips. Actually, the development consisted in the layout of the boards. All schemes are taken from the Internet. Board tips, acoustic protection and cooling, I threw my friend. I collected the preamplifier from my own reserves. Well, I had to, unfortunately, supply electrolytes from those times. In the future, perhaps I’ll replace it, since it takes up too much useful space. I plan to use the amplifier myself for the bass guitar. The preamplifier is equipped with high and low frequency controls. Having rummaged on the Internet, having tried several schemes, I decided to turn to the old, good Soviet technology. Several amplifiers of Radio Engineering 101 passed through my hands at different times. They have good tone control, especially in the low-frequency range. So I copied the timbral block to K157UD2. What is good about this circuit is that there is a gain correction for the linear output. But the voltage at the output of the timbral block is not enough for the buildup of the terminal, since the input of the TDA7294 is 0.7 volts. I had to make an amplifier for a linear input on a separate chip TL071.
On the front panel are two nests for tulips and a jack for a guitar jack. At the top are three cooling and protection speaker LEDs. Knobs for volume and tone controls, as well as a volume indicator. By the way, an extremely useful lotion. The indicator input was taken from the terminal input and adjusted to a maximum of 0.7 volts. Actually according to the scheme, nothing unusual for hams. If you wish, in our time you can buy all ready-made boards. I want to show exactly the layout. Perhaps in a traditional horizontal design it would be easier to organize everything. BUT we are not looking for easy ways, and besides, I wanted something like that in style steampunk. Another plus when transporting, the handle on top is very handy.
The photo shows what and where is located. From left to right there is a power amplifier with a radiator, a cooler, electrolytes, and above them is the protection and inclusion of the cooler.
This is how the board of the input amplifier and tone block looks.I did not use foil textolite because of its absence. I just clean the old boards and mount them. Not very neat, but it works the less. The input amplifier is also on mikruh TL071.
This is an amplifier for line input, installation, too, can be said to be mounted.
On the back wall is nothing ordinary. Connecting speakers and fuses.
And one more perspective in the end. Such homemade I did it. We tried under the C90 column, everything works. Only I doubt the declared power of 70 watts, in my opinion a maximum of 40 watts.