Sam’s LM-386 Amp, a picture of my workbench, and blue tubes.

sams cigar box amp

Sam’s non-cigar box amp

My brother-in-law came over because he wanted a cigar box amp. He also wanted to build his own enclosure, and I think it looks superb. It sounds great, too. With the limited sound holes and a totally enclosed box, it creates low end and crunch like no regular cigar box. I am including a picture of it just to show it off. He had some great workmanship. I believe he used 3/4″ plywood, which he didn’t quite like because it chipped every time a tool came near it. He painted it with eight coats of black paint and then furniture polished it.

The second order of business is that I left my guitar amp in a public place and somebody thought they would play it. Well, I’ll be if it didn’t start glowing blue. I guess the sound is okay, but I’ve never seen my tubes glow blue before. I’ll probably

6DG6 (6DG6GT) tubes glowing blue

6DG6 (6DG6GT) tubes glowing blue

buy some new tubes for it in the near future. They’re pretty inexpensive. It’s the shipping that kills. This is the tube amp that I built using the featured tutorial on Instructables. I’ve talked about it before. If I could really wail on some guitar, I’d make some recordings of it. Dreams and arm pits.
Here’s the picture of the 6dg6 tubes glowing blue. I really like how it looks. It’s a beautiful sight to me, and if they weren’t so stinkin’ hot and if the amp wasn’t so big, I’d just leave these babies glowing as a night light.

I really love that!!! They only glow blue when the HT is on. I’ve read conflicting reports about blue tubes, but I really don’t have a professional opinion of my own. It’s mainly credited to impurities in the vacuum. Either way, I’m not to worried about it. Tubes go bad. Big deal. It’s an opportunity to buy presents for my amp. :) (I learned from a reader that blue tubes are okay. Thanks to Kent L. for emailing me about this. In short, Kent says that blue along the envelope is a sign of a good vacuum. 10-22-2012)

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Ruby Amp (LM386-3) Circuit Power Consumption Test

I had to try it. I hooked up my variable power supply to the voltage connector of one of my amps that is soon to be for sale. I was wondering what the current consumption would be for those of us that like 9 volt batteries.

To start off, 9 volt batteries do not function well below 7 volts. Without getting into the engineering aspect, the battery just can’t deliver enough current at this point. The LM386 will work at 5 volts, but once a 9 volt battery gets that low, its voltage sags dramatically. If you don’t believe me, do a Google search on the internal resistance of batteries. :) Continue reading

This week @ Tech-tut (August 19, 2010)

The Lumenlab micRo CNC arrived this week, and I have been completely busy preparing some blogs for it. I started out with an article explaining how to install Ubuntu and EMC2, but anything past that is going to be specific to my machine. I will outline the testing process that I took, and give references to those who’ve gone before me.

Setting up the CNC router was a piece of cake. I took it out of the box and had it running in 15 minutes. Lumenlab had all of the required files and setups ready to go. I’ll explain the whole process in detail soon.

The rest of my time is being devoted to school work. I will be adding some new Cigar Box Amps to sell on Etsy.com if anyone is interested in buying one.

Have a great week! It’s more than just a project…It’s where all your money goes.

This week @ tech-tut (August 5)

Things are going well this week. A few Cigar Box Amps have been sold on the eBay. One CBA was modified for a gentleman interested in buying it on Etsy. I added a DC jack for use with a wall adapter. I am thinking that the wall adapter jack needs to be standard on all of the CBAs built by me because several people have asked about them.

A couple of repairs were sent my way this week. A few Danelectro pedals came through that had some loose parts. A touch of resoldering brought them back to a reliable life. Two straightening irons were repaired. One had a short in the plug and at the elbow. I spliced and resoldered the joints and heatshrinked them back to life.

This weekend I’ll be assembling a few more Cigar Box Amps. I have enough supplies to build two more before having to reorder parts. I’m thinking about exclusively selling them on Etsy from now on. I sell them at such low prices that I’m working for about $2 an hour after the eBay fees are paid. That’s not even hardly worth my time, but I enjoy building them, and I believe Etsy.com will be the best route for me to go.

Finally, I’m preparing my work shop for my new Lumenlab micRo V3 CNC router. I posted a new entry with a photo here–> Preparing for a Lumenlab micRo V2(V3) CNC Router It’s due to ship any day now.

Thanks for visiting Tech-tut.com. Remember, “It’s more than just a project.”