diyAudio - Blogs - mlise A community dedicated to helping everyone learn the art of audio. Projects by fanatics, for fanatics! en Sun, 28 Dec 2014 00:34:45 GMT vBulletin 60 diyAudio - Blogs - mlise All up (mostly) amp Wed, 12 Jun 2013 01:33:48 GMT Here's a shot of the waffle all built up. It's 32" wide and 32" tall with the amps on top, and flat. Typically deeper cabinets sound bedder then shallow ones, but the front to back bracing in this seems to fix it. Mica had an excellent suggestion to hinge it to fold in half. That's awesome. With a vertical hinge in the middle, it's all closed and protected to travel. Ron suggested being able to stack them 3 cabinets high for a wall of sound+ effect. Typical amps have basically a point source. The GD's wall of sound had vertical linear arrays (precursor of the modern line array by 40 years) of drivers. With this amp, you could stack them vertically and horizontally to make a field array. if you got closer, it wouldn't get louder, farther away it wouldn't get lamer. Mwaah ha ha ha...
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Cabinet for class D bass amp Mon, 10 Jun 2013 19:54:53 GMT As seen in the D2 amplifier posting, I had built a pretty normal 4X10 cabinet with Eminence Beta10A's. I was talking to Ron Wickersham up at Alembic, and he suggested an idea he had. Make the cabinets shallow enough that the back pole pieces of the speakers were against the back of the cabinet and vent them outside. Sealed back drivers are problematic in bass amps because they overheat and the coil resistance either goes way up and the sound wimps out, or the coils outright melt. The Beta 10A's are vented and I've even gotten them up to where you can smell the varnish burning off the coils.
Flattening out the cabinet made it quite large. 32" square and only 4" deep.

The frame around the outside is oak, but the front and back are only 1/8" masonite. To firm it up, there are masonite braces front to back radiating from each speaker into the corners and edges of each enclosure. There's a wooden ring glued to the back of the driver and the back is screwed to that. The cabinet ended up being amazingly solid. No rattles or flexing at all even with 900 watts going through it.
I brought the prototype up to Alembic to show off. I've chatted with them in the past about an Alembic bass amp.

Alembic - Fine handcrafted basses and guitars

Ron was clearly startled by how good it sounded. I'm sure he would have taken time to listen to whatever I brought, but I wasn't going to bring up something that was lame. We set it up with an F1 preamp and an ELF processor, 2 speakers on the normal and 2 speakers on the ELF channel. It could probably be 1 and 3 though. They have a few folks lined up to come in and give it a whirl. ]]>
Class D Bass Amp Mon, 10 Jun 2013 19:24:37 GMT I've been working on a lightweight class D bass guitar amplifier. I originally started with the D2 Audio chipset now sold by Intersil.

I found that there was practically no support. Even though I was an FAE at Intersil, I couldn't find any documentation and most of the folks that worked on those parts had been laid off. The D2 parts were great. they had 12 output drivers per chip with a DSP pool, but it would be impossible to actually make a product with them.

Looking around, I found a bunch of parts at TI. I don't know if these came from National or TI originally, but there's a bunch of parts available at different power levels. The all seem to have integrated power stages. I chose the TAS5630. It has an analog input and will drive 300 watts into each of two channels. I ordered samples and started to collect parts to build an initial prototype, but I found complete amplifiers from Sure Electronics. The whole thing, up and running is $70!

2 X 300Watt Class-D Audio Amplifier Board - TAS5630_Class D Amplifier Board_Audio Amplifier and other Audio Boards_Audio_Sure Electronics' Webstore

I couldn't even buy the parts surplus for that without the PCB. I bought two amplifiers and two 350 watt 48 volt power supplies for $200. For an extra $50 they all arrived in three days. ]]>