SuperMegaUltraGroovy » Gainclone

Boom! (Goes the Gainclone)

chris — Thu, 26 Oct 2006 02:15:35 +0000

Building the Kookaburra was a lot of fun. I managed to not screw up the soldering job, and initial tests indicate that it’s doing the right thing.

However, when trying to integrate it into my amp’s case and pipe its output to my amplifier, sparks flew. I managed to melt a trace off of one of my power regulator boards, and I’m not sure if the individual amplifier boards survived. For now, the amp is completely dead until futher notice.

I think that during my wiring, I might have inadvertantly caused a short somewhere which caused this miniature light show.

I just can’t seem to catch a break with electronics/computers this past month. First the botched MacBook Pro repair, then a faulty firewire enclosure, and now a blown amp! I think I’m cursed…

Kookaburra in transit!

chris — Fri, 20 Oct 2006 17:47:25 +0000

It turns out that the volumeless amplifier idea didn’t last very long. Once the amplifier got hooked up to my MacBook Pro’s internal audio source, the granularity of the volume control was not nearly enough for day to day use. Also, thinking of headroom, it’s always best to have a digitally controlled output attenuated in the analog domain, rather than digitally.

After some initial research into what it would take to design/build my own preamplifier section to handle volume control and buffering, I decided that a kit was the best way to go. Enter The Kookaburra.

This preamplifier is designed exactly as I would have done it myself, but even better (because honestly, I’m just not that great at designing circuits). By going with a kit, I get a bag of parts that I can attack with my soldering iron, and get a tried & tested product as the output (provided I don’t screw up the soldering job too badly).

Currently I’m waiting to receive my Kookaburra kit in the mail, and I plan to build it shortly thereafter. I hope to post some further updates on the progress of the project in due time, along with some better pictures of the inside my amp.

My New Old Amplifier

chris — Wed, 20 Sep 2006 20:25:00 +0000

A long time ago, I built my own amplifier. This was a fun project, and the results were pretty decent. I never did post the results of the project, so here’s a picture of the results.

Obviously, I put a cover on there, and the end result looks fairly decent (a throwback to the 70s, when wood was commonplace on electronics).

On the front of this unit (not shown), I have a log potentiometer that served as the “preamplification stage” (basically, a volume control). Over the course of this amp’s life, this volume control would drive me absolutely bonkers because at about 10% of the volume level, the left speaker would shoot up to about 50% until you went down to 5% volume level.

I set up some speakers in the office recently, and decided to use the amplifier a little more. I realized quickly that I could just leave the amp playing at full volume, and simply control the audio level on my MOTU Traveler. This worked great.

So, this past weekend, I went to the “electronics lab” (basically, my basement) and decided to modify my amp a little more. I removed the connections to the volume control, and now the unit behaves more like a pure amplifier.

During this exercise, I reorganized a lot of the internal wiring, and decided that I should really separate this project into a power supply unit, and an amplifier unit. This would allow me to more easily experiment with other amplifier designs, and also a nicer (read: smaller) case layout.

I wish I had more time to play with these projects…

Progress, Strangeness…

chris — Fri, 21 May 2004 14:27:00 +0000

Interestingly enough, over the past few days I’ve sat staring at the “new entry” screen with so much to say, but no energy to actually throw it down on the keyboard. That’s the strangeness part.

The progress obviously has to do with my amp. I’ve wired up three iterations of chip amps that have gone from the LM3875 to the LM4780 (and back again!). All of them were wired point-to-point (see image).

To say I was impressed by how good they sounded on my first attempt would be an understatement. Most of the amazement came from the “did I just build THAT?” aspect rather than the “I’m never buying an amp again” category.

Now I’m in the stage where I’m trying to pretty everything up so it fits into a box rather than this configuration shown below.

PCBoards have been etched, and I’m drilling some out tonight. Hopefully I’ll be successful with that and I can move on to cleaning up the power supply.

Boards are built

chris — Mon, 10 May 2004 07:01:00 +0000

I built up two board designs. One of the designs was for the regulated power supply, which I threw together myself from schematics I found online from Pedja Rogic. The other design was a parallel LM4780 amp done by Brian, who is known for building the LM3875 boards that were so popular before. I figured it would be best to etch/build my first double-sided layout that was designed by someone else.

The power supply building was quite simple, since it almost doesn’t need a PCB. I like using PCBs for anything I build, because “dead bug” wiring gets messy real fast, and is a risk for electric shock. I built both PS PCBs in a few hours, and they worked on the first try.

The double-sided PCB was an interesting one to build, as it involved a lot of complex soldering tasks to get done. Luckily my new iron is good at this sort of thing and doesn’t allow itself to get hot enough to be dangerous.

Now that everything exists in its own “permanent home” I can start to visualize how it will all fit into an enclosure. Pictures of the built boards will come soon, and I will post the PCB artwork for my power supply here as well.