RP5's have a decent amount of power to them. These little SBC's have come a long way. 
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DIY bass amp
- Thread starter 6thplanet
- Start date
I think LEDs, especially RGB, are great. They're somewhat of a "cheap trick" that nobody seems to be doing.
What I'd like to do one day is get strips that function as actual spectrum meters so people see what frequencies I'm playing in real time. lol. I haven't looked too much into it yet but, there's got to be a way.
I'd want a signal split first thing in the chain, of course.
Large LED VU bars are all over Ebay and the usual import websites for cheap -- $50 or less.
As a fun light show, they're fine. Amp companies probably don't put them in their products because it's added expense and faceplate space for something that implies they're meant to be functional analysis tools which will probably in reality not be accurate, interpreted properly, or otherwise more useful than something simple like a clipping light.
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I actually thought about incorporating some sorta LED bar display. Ended up deciding against it. It's just more work, I'm already kinda overwhelmed.
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I did. I have the 9V wire sleeved with the input cable. I hooked up all the pedals I had, I think it was 5 total. It powered them all and was no nosier than powering them off a separate supply. Actually in the test mule, it's much closer to the input jack.
Retired engineer. Very nice job! An interesting idea for clipping circuits is using LEDs for soft clipping, a hard diode for one polarity and an LED for the other for asymmetrical clipping (2nd harmonic) or my favorite, a 6AL5 twin diode tube. Doubt anyone is still making them.
Thanks!
I tried LEDs, red and green, 1N4148s, and various voltage zeners in various combinations. In the end I settled on the 2.4V zeners in series. It allows enough symmetrical clipping without squshing the signal to much at full clip. The preamp itself is capable of nice asymmetrical clipping thanks to the cathode clipper in that last stage, which I auditioned several values there before settling on the 3.6K.
I tried LEDs, red and green, 1N4148s, and various voltage zeners in various combinations. In the end I settled on the 2.4V zeners in series. It allows enough symmetrical clipping without squshing the signal to much at full clip. The preamp itself is capable of nice asymmetrical clipping thanks to the cathode clipper in that last stage, which I auditioned several values there before settling on the 3.6K.
The 6AL5 sells for around $5 as NOS. I’ve seen them used in radios.
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Picked up the logo badges yesterday....
If anyone needs anything laser etching/engraving done, hit my buddy up!
If anyone needs anything laser etching/engraving done, hit my buddy up!
Assembled one to test that I have everything worked out and all the parts and pieces. All good!
I'll have disassemble the stuff off the back once the sticker is made, which is still in the works.
Stupid hot weather has kept me out of the garage, so applying the finish to the front panels will have to wait. Looking like Saturday might not be to bad.
I'll have disassemble the stuff off the back once the sticker is made, which is still in the works.
Stupid hot weather has kept me out of the garage, so applying the finish to the front panels will have to wait. Looking like Saturday might not be to bad.
Ran some frequency response measurements.
EQ controls set to noon, Depth in position 4. This shows what the EQ shift switch does.
Next is the min/max of the EQ controls. EQ shift switch in the down position, Depth in the 4 position.
Treble:
Mid:
Bass:
I also did the Depth control settings, but after examination, I think I can do better. I'll post those up after some parts arrive and installed.
EQ controls set to noon, Depth in position 4. This shows what the EQ shift switch does.
Next is the min/max of the EQ controls. EQ shift switch in the down position, Depth in the 4 position.
Treble:
Mid:
Bass:
I also did the Depth control settings, but after examination, I think I can do better. I'll post those up after some parts arrive and installed.
As I was measuring the frequency response of the controls, the depth control was the one I was really interesting in seeing what was going on. When designing the amp and decided to add the depth feature, I kinda guessed at the values I used for that function. After building it, obviously it was working like it should, but the different positions of the switch weren't exactly what I had hoped for. The measurements soon showed what was going on as well as what I was hearing.
The original capacitor values were:
Position 1 - 1uF
Position 2 - 4.7uF
Position 3 - 10uF
Position 4 - 22uF
Here's what that turned out to be:
That's when I knew things could be better. Position 1 was fine, but the other three were just to similar. I then tried taking Position 2 to 3.3uF and Position 3 to 6.8uF. Things got better, but still had room for improvement. I ended up with
Position 1 - 1uF
Position 2 - 2.2uF
Position 3 - 4.7uF
Position 4 - 22uF
Now each position has a distinct control over the low end "depth". This in conjunction with the bass control allows really nice control of the low response.
I have to admit, I use position 1 in my band. It's heavy metal, tuned to C. That setting is great for controlling the low end and playing loud. At home, position 3-4 are great for dialing in low volume tones.
The original capacitor values were:
Position 1 - 1uF
Position 2 - 4.7uF
Position 3 - 10uF
Position 4 - 22uF
Here's what that turned out to be:
That's when I knew things could be better. Position 1 was fine, but the other three were just to similar. I then tried taking Position 2 to 3.3uF and Position 3 to 6.8uF. Things got better, but still had room for improvement. I ended up with
Position 1 - 1uF
Position 2 - 2.2uF
Position 3 - 4.7uF
Position 4 - 22uF
Now each position has a distinct control over the low end "depth". This in conjunction with the bass control allows really nice control of the low response.
I have to admit, I use position 1 in my band. It's heavy metal, tuned to C. That setting is great for controlling the low end and playing loud. At home, position 3-4 are great for dialing in low volume tones.
Front panels, one coat of shellac sealer and three coats of Waterlox Original.
Today I got all the front panels fitted to their respective enclosures. All the lighting is also done. Still waiting on the stickers...
Had another bass player buddy give the test mule a try out, down to 6 to get rid of.
Had another bass player buddy give the test mule a try out, down to 6 to get rid of.
Hope all are having a great weekend!
I picked up the chassis stickers. Got a little more done on the amps...
I picked up the chassis stickers. Got a little more done on the amps...
Finally getting to assembling these things. First up is the DI circuit as its harness runs under the preamp board.
Today I did the IEC power connector, fuse holders, and transformer on each one. The IEC connector assemblies were harvested from Bose Powerstands being scrapped for various reasons. No point in reinventing the wheel.
The transformer is an Antek piece, part number AS-05T-200. It's a bit overkill for this amp, but had the voltages I needed and is easily obtainable. Not to mention affordable. I used an aluminum bolt to attach it.
The transformer is an Antek piece, part number AS-05T-200. It's a bit overkill for this amp, but had the voltages I needed and is easily obtainable. Not to mention affordable. I used an aluminum bolt to attach it.
This round I installed the preamp board, front trim panel, heatsink, and the rest of the switches. Next up will be the power amps.
