It's a kludge of ideas mostly found on the web. It uses an MPF102 front end and an LM386. It has a drive control, a tone control, a gain control (for the LM386), and a switched "overdrive" adder. I am going to proceed with ordering 10 PCB's, with which I can do some component substitutions and comparison testing before finalizing the schematic.Please also specify which circuit you've made. Thanks in advance.
There are many bridged car radio power amplifier ICs available.Actually, I'm so impressed I am going to build me another portable amp with an 8" speaker but not with the LM386, something with more power running off a 12V SLAB.
A Jfet with a source resistor biases itself.Silly question, but I'm curious. Why is a JFET chosen over a MOSFET or BJT?
Thanks, I'm assuming the self-biasing is due to the depletion-mode operation (have yet to study JFETs)...A Jfet with a source resistor biases itself.
A Mosfet (a little 2N7000?) needs complicated biasing.
A BJ Transistor also needs complicated biasing and is difficult or impossible to get a very high input impedance.
Correct.Thanks, I'm assuming the self-biasing is due to the depletion-mode operation (have yet to study JFETs)...
Well, 1; modern magnetic guitar pickups are too high in treble and generally you turn the treble down, and 2; it's a fact that pro-designed amps where done with a single LM386 and no JFET preamp. I spent years repairing amps.AudioGuru said:... "Depending on your personal tastes, there may be a potential down side to the 386 designs. The input impedance is listed at 50k, according to the datasheet. This is quite low and causes some loading of the guitar signal. There is some degree of high end signal loss."
Crappy! Any decent piezo pickups for acoustic guitar have a little preamp built in, usually in a box on the lead. Who plays those silly acoustic things these days anyway?Tracecom said:...Do you happen to know what the output is from a typical piezo pickup?
I bought this oneAs for building a class D portable amp, ebay is full of finished d-class amp modules for pennies like this one;
10W+10W from 12v for about $11.
Sad, but true. I was in an MBA program in 1992 and the buzz was about a coming global economy. I remember thinking at the time (and actually said it in class) that I didn't believe it would benefit the US. Now, I get the benefit of super cheap electronics and the US unemployment rate is over 15%. Hoodathunkit?Stunning example of buy-versus-make weighted very heavily to BUY.
I just read the latest biography of Jobs. He was very reluctant for a long time to trust outside manufacturers...even some right across town in Cupertino. Now, I suppose all Apple products are from China. I haven't bought an Apple product since the original Mac; between the initial purchase and "upgrades," I sunk over $4,000 in mine and it still didn't have a hard drive. I sold it in 1988 for $1500 and bought a PC. The Mac still was amazing for its time (especially without a hard drive.)Got my MBA in '89. If I only new then what I know now. Like, why didn't I buy 1000 shares of Apple instead of 100?
Yeah I expected as much. But still a good 5w with low distortion is a huge step up in sound power to the previously discussed LM386 running from a 9v battery.The datasheet for the PAM8610 class-D stereo amplifier shows that its output power is 5W per channel at low distortion, 8W at medium distortion and 10W at high distortion when its supply is 12V.
A bridged amplifier that has no saturation voltage loss with a 12V supply has an output of 9W at clipping into 8 ohms. But all amplifiers have some loss so the output is actually only 5W.It might also be possible to make a few mods on the PCB and bridge the two stereo amps to give 10-20W? I'm not sure if that particular D-class amp chip is bridgeable.
Why bother trying it. Instead look at its datasheet.I'm going to try out the TDA2040. I'll let you know how that turns out at 12V.
I see from the datasheet that the minimum Vs is 8 V. What would be the power out into 8 Ω with an 8 V supply, and, if you don't mind, point out in the datasheet where you find that information. Thanks.EDIT: Look at the TDA2005. It is a bridged amplifier that with a 12V supply produces about 7.2W into 8 ohms at clipping.
by Duane Benson
by Aaron Carman
by Aaron Carman