diytube.com

Someone mention a 1KW tube amp?

http://www.chambonino.com/construct/const9.html

The Karlson isn't a folded horn, it is its own unique design, closer to a ported. vented cab. The designers (John Karlson and Wayne Green) applied 1950s microwave antenna designs to audio wavelengths.

I haven't tried it for bass guitar use, just LOUD music, and it delivers the goods in the low-freq department, effortlessly.

The woodworking for these cabs is fairly difficult - I was lucky enough to find a pair of these cabs at the local town dump / recycling center, in the "swap" section. So someone else did all the hard work about 40-50 years ago. The design goes against all of the common wisdom, no acoustic "stuffing" inside the cab, in fact it is interlally coated with some form of hard resin or epoxy. The venting is a series of long narrow slots, and the front baffle has a strange log-curve, and the speaker itself is mounted on a slanted bafle behind this.

A picture is worth about ten thousand words in this case...

Original "Karlson" posting starts here:

http://diytube.com/phpBB2/viewtopic.php?t=781

/ed B

I think I find myself in the same boat! A friend has just offered to me a "chance in a lifetime"...not sure how to take it but I have an order for a 100w bass amp, hopefully only the head. I think I may take a whack at the BFA that is located here. I let the friend know that it will cost quite a bit...havent heard back yet, but imagine I will has this is the 3rd or 4th time he has mentioned wanting one.

./e

The BFA isn't that difficult. Because of the weight, the chassis has to be steel which makes it a little harder to work than aluminum. Compared to an SVT it is a pretty simple device. Let me know what you decide, I'll help anyway I can.

Don

Don,

Awesome! so did you ever change out the BFA for KT90s or 100s? I'll send a PM.

Thx

Erick

These are the most recent schematics for the BFA:









Don

Don,
Very cool,

Thanks!

Erick

ERRR! I just noticed a mistake and it's an important one. The 1 meg resistor from the input to ground should be 10 megs. With only 1 meg on the input like that it won't work on piezo pickups. I will make the correction and delete this sometime in the next few days.

Don

Later... OK, I fixed it.

"quote from psycho bass guy @ last bass out post: You'd need the voltages and transformer specs to really do anything with that schematic. As an aside, the PT looks like a Marshall clone and the OT looks like the OT on a Sunn 2000S. I would expect a beefier PT could up the power and run cooler. Still, it works- nice looking booger."

the transformer specs i have, could you post the voltages if you have them written down?

Uhhh... Let's see, B+ is 535 volts, I remember that. What the rest are, I don't know.

Don

thanks Don