Big bass amp

a fine line between stupid and clever

Someone mention a 1kw audio tube amp?

Postby mesherm » Fri Oct 15, 2010 12:53 pm

Someone mention a 1KW tube amp?

http://www.chambonino.com/construct/const9.html
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Postby EWBrown » Fri Oct 15, 2010 4:27 pm

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
Last edited by EWBrown on Sun Dec 19, 2010 7:31 pm, edited 1 time in total.
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Postby 77seriesIII » Sun Dec 19, 2010 10:38 am

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
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Postby dhuebert » Sun Dec 19, 2010 6:19 pm

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
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Postby 77seriesIII » Mon Dec 20, 2010 1:41 am

Don,

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

Thx

Erick
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Postby dhuebert » Fri Dec 24, 2010 12:39 pm

These are the most recent schematics for the BFA:

Image

Image



Image

Don
Last edited by dhuebert on Tue Dec 28, 2010 11:35 am, edited 2 times in total.
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Postby 77seriesIII » Sat Dec 25, 2010 11:12 am

Don,
Very cool,

Thanks!

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Postby dhuebert » Sun Dec 26, 2010 9:56 am

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.
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Postby cw » Fri Jan 27, 2012 10:19 pm

"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?
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Postby dhuebert » Mon Jan 30, 2012 3:26 pm

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

Don
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Postby cw » Mon Jan 30, 2012 4:25 pm

thanks Don
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