DIY Airbrake...

[Icetech]

I have had mine for like 4 months now.. and really recommend drilling holes on the sides to let heat out if you are using it with anything over 50w.. with my marshall the ohmite got hot enough to leave a white mark on my finger (shouldn't have touched it to start with:)

[pdrie]

I used the same Allied parts list as Custom 100. I also bought the following 2pole 6 position switch from Allied:

676-4258 A20615RNZQ (EA) $3.66

It looks like it will work.

Paul

[outtahear]

Ordered (bedroom)Potentiometer from Mouser-catalog had it listed @ $30 -is. When I called my order in-it was $40!
3 588-RJS150E
50watts 150OHMS 1 $41.84.

Like every time I order from them prices seem to rise/drop a bit, but a %30 jump??

[matt]

I built mine up today. Haven't really had a chance to crank my amp up with it yet. But, at "medium" volume - I'm more then impressed with it.

[pjl]

I have understood that the Airbrake is an L-pad attenuator with one fixed resistor and one tapped at convinient locations. Question: why not use two tapped resistors to get better impedance match? Calculating the values is easy: http://www.lalena.com/Audio/Calculator/LPad/

Pekka

[joe6v6]

Where is the Layout and info for the airbreak? Does anyone use this to Gig with, to get cranked express tone & sustain in a smaller verue?

JOE

[matt]

Any potential cautions with regard to using one of these with an amp? Any impedance related issues ie. - does this work with any amp/cab combo?


Thanks in advance for any help/answers you might have.

[toneman]

Bought my bedroom potentiometer here . Was a good price http://www.plccenter.com/buy/Ohmite/RJS150

[KGW]

I haven't built mine yet, but it seems that a heat sink would be a good idea. Maybe a fan as well. My HotPlate has both.

Anyway, I looked in the Mouser catalogue a bit and didn't really find any large heat sinks. The chassis is 9x5x2, so the heat sink could be up to 9x2.

Also, Lorlin switches are really bad, I would recommend Electroswitch (MSR# 690-C4D0206N-A) or Grayhill (from DigiKey).

I'm not sure how to do the fan. I guess I could open up my HotPlate and see how THD did it.

The plan is:
Eventually, when I get another 2x12 cabinet and build an Airbrake, I am going to use an ABY box an my DIY Express and DIY Marshall 1987. That should be sweet.

[toneman]

Heat sinks, yet to label the controls. right side is bed room level, I need to round the corners on the heat sinks. they are from an old amp that died.

[Rick]

Where is the layout for these? I would build one if I had a layout...

[KGW]

Heat sinks, yet to label the controls. right side is bed room level, I need to round the corners on the heat sinks. they are from an old amp that died.

Does anybody know a source for heat sinks similar to these? I found a place in New Zealand, but a source in the USA would be better. http://www.gumboot.com/cgi-bin/ezshop/s ... gorygo.x=1
They are nice though.

[Rick]

If you know or can find someone who fixes PC's, old power supplies are a source for quite a few goodies I've found. There are usually a few heat sinks on the bridges, the wire is generally decent quality 300V rated PVC in 20 and 18 AWG, and other useful things might be found in there, like a screw mounted IEC socket, etc.

[doctord02]

Apex Jr has heatsinks... poke around on his misc and new additions page...

[d95err]

I have understood that the Airbrake is an L-pad attenuator with one fixed resistor and one tapped at convinient locations. Question: why not use two tapped resistors to get better impedance match? Calculating the values is easy: http://www.lalena.com/Audio/Calculator/LPad/

Pekka

Not exactly an L-Pad. It is a fixed shunt, variable series resistance attenuator. It doesn't do proper impedance matching, but apparently that's not a big problem.

The reason for not using an impedance matched L-Pad? Well, because that's not how Ken Fisher did it...

(I'm using a variable 100W hifi L-Pad built into a speaker cabinet. It works OK for minor attenuation, but there is definately major tone-loss once the attenuation goes below -6dB or so. Perhaps the Airbrake works better.)