Badcat Unleashed

[JazzGuitarGimp]

Even Kenny G could hear the difference.

Now THAT'S funny!

[stephenl]

After few hours of playing, my Unleash developed a nasty buzzing sound through he speaker.... I'm sending it back to CA today . The noise seems to ramp up with the cooling fan on power up. The fan is supplied from a 12vdc aux power supply on the B&O Ice Module PA.

[evh0u812]

http://www.guitargear.net.au/discussion ... 991.0.html

Here another method i came up with after reverse engineering an ultimate attenuator.
They sound pretty amazing.

[LeftyStrat]

http://www.guitargear.net.au/discussion ... 991.0.html

Here another method i came up with after reverse engineering an ultimate attenuator.
They sound pretty amazing.

Interesting. I've heard good things about the UA. I didn't realize it was the same as the Ho design.

[Gaz]

http://www.guitargear.net.au/discussion ... 991.0.html

Here another method i came up with after reverse engineering an ultimate attenuator.
They sound pretty amazing.

Really cool project. Nice going!

[Reeltarded]

That is nice!!

[evh0u812]

This was mark II before I sent it to the lucky customer. Added in DC speaker protection and turn on/off thump delay. Also tailored the load and made it selectable for 8 and 16 ohms with 450w of properly heatsinked load rather than the 2 un-heatsinked 50 watt resistors in the originals.

[IMG654]http://i275.photobucket.com/albums/jj29 ... 490fa8.jpg[/img]

[IMG750]http://i275.photobucket.com/albums/jj29 ... 3e44df.jpg[/img]

[IMG615]http://i275.photobucket.com/albums/jj29 ... 3a36e1.jpg[/img]

[IMG691]http://i275.photobucket.com/albums/jj29 ... 873c65.jpg[/img]

[Reeltarded]

It is beautiful. Very nice work!

[M Fowler]

That is a great looking attenuator.

Mark

[dorrisant]

Nice. I want one.

Tony

[vibratoking]

Nice looking attenuator! I love the clean build. So reversed the UA? I didn't see a schematic in the link. Care to share?

[dorrisant]

Here's another interesting approach to simulating the reactive load of a speaker, with even a voice coil warming feature:

http://www.richardbrice.net/hot_lamp.htm

Lefty... I wonder, is that what Sam from Samamp uses? They sounded pretty good.

"samamp guitar amplifiers are point to point hand wired with "class a" vacuum tube circuitry. The V.A.C. - Variable Amplitude Clipping control is a unique feature with selectable wattage settings. The point at which the output tubes clip is sometimes called the sweet spot. This is volume compression and output limiting at its best. How loud the amp is at clipping is determined by its output power. The V.A.C. circuit is a different way to control the output power of a tube amplifier. Not a built in speaker attenuator and not in the signal path, the V.A.C. circuit uses lamps (light bulbs) to limit voltage and current flow into the power tubes. This balanced circuit forces the power tubes to act like smaller power tubes. Power tubes run cooler with V.A.C. and all of the output power reaches the speaker. 
Readily available lamps are used: 15 watt exit sign, 7 watt "night light", and 4 watt "night light".  Take advantage of the "feel" and touch sensitivity that coincide with volume compression and output limiting!!"
From his page: http://samamp.com/

EVH... You might get away with posting a BOM. Then we could pick your brain . I for one would love to know where you sourced your parts. I wish I could have seen the pics that were removed just to see how bad the UA was.

Tony

[Zippy]

The V.A.C. circuit is a different way to control the output power of a tube amplifier. Not a built in speaker attenuator and not in the signal path, the V.A.C. circuit uses lamps (light bulbs) to limit voltage and current flow into the power tubes.

Readily available lamps are used: 15 watt exit sign, 7 watt "night light", and 4 watt "night light".

"Plug and Play" resistor swapping in series to the power tubes.

R=(V^2)/W

15W >> 960 ohms

7W >> 2K ohms

4W >> 3K6 ohms

I don't know that I'd trust a light filament in an amp. I've had too many night light failures. Maybe a fan-rated lamp but even those fail with few hours on them sometimes.

[LeftyStrat]

For those not wanting to go through the full thread on the Randall Aiken reactive load, here's the sound clip comparing direct to speaker, reactive load to SS amp, and resistive load to SS amp:

https://soundcloud.com/ilya-v/straight-vs-reactive-vs

You can definitely hear a difference between reactive and resistive. I'm trying to decide if it is just the top-end. This would possible explain why the UA sounds good, since it uses the inductor to enhance the highs.

[LeftyStrat]

Lefty... I wonder, is that what Sam from Samamp uses? They sounded pretty good.

Definitely sounds similar.