DR: OT @ 2 Ohms/ 10" spkr Q.

[Chuck H]

I have mine set up with an inductor/capacitor circuit for an active load. So, even more stuff. This unit has the cement (ceramic block) resistors spaced only a half in apart and sandwiched between two pieces of aluminum (2"x 3/16" about four inches long) these are mounted to the top of a thin gauge aluminum box that is only 3"x3"x6" with all the other stuff crammed into it. Running my 2xel84 amp into it balls out for an hour only gets it very warm/almost hot. It never gets hot such that you can't handle it.

In other words... It's sounds like you'll be alright. If you ever notice it getting really hot perhaps you can add a heat sink.

[eschertron]

If this contraption is on a champ, how much heat are we actually dissipating? 5W? 8W? The components are rated at a few dozen Watts (taken collectively), So even on a bigger amp, we're going to be looking at medium incandescent light bulb - sized heat generation. On the smaller amp, I don't believe heat will be an issue as long as there is any amount of airflow around the resistors for convection purposes. I think you'll be OK with the pedal box as mounting surface.

guarantee of results is not implied by this endorsement

[guitician]

You could augment it with added fins too... 624-25ABT4E Wakefield | Mouser

A lot of these floating around from the old PC days...

[Sea Chief]

Mouser has a Euro presence I think. Perhaps you can place an order for the aluminum resistors and a small-ish BUD or Hammond aluminum chassis.?. This would also make it so you can use it with any of your amps. If you must prioritize funds, well, that's ok too. It's not a race.

Guitician- thx for link.. I did see those etc, but how Id cut it down I couldnt visualise.

Ok what Ive done maybe a bit odd, but used what I had: the small stomp box without the base plate. Ive mounted the rheostat, switch, & jacks in existing holes (made for some pedal or other). Then holes made in side to mount the fat R's (alu housed types). So the R's sit on the longside, this the topside. The lower longside 2 holes made to mount it 'up' IE perpendicular to a small ply square 'base'. So its open-backed, switch and dial on front L and R of each other, jacks in one short side.

Sort of like one big heatsink with everything squashed in, but open at back for air & R's mounted on its 'top' for hopefully most air and direct to the case for a bit of heatsink.

What do you think.. can you visualise it? Its actually really rather brilliant.

[guitician]

Yeah, or he could just use the bottom cover... Mouser UK link http://uk.mouser.com/ProductDetail/B...RvIigNX9OeYuQV
The eBay link was UK too.

Found these 5% types, less cost... http://uk.mouser.com/ProductDetail/W...6xiu1e%2fcQ%3d

[Chuck H]

Mouser has a Euro presence I think. Perhaps you can place an order for the aluminum resistors and a small-ish BUD or Hammond aluminum chassis.?. This would also make it so you can use it with any of your amps. If you must prioritize funds, well, that's ok too. It's not a race.

[guitician]

I found this on the bay... ALUMINIUM SHEET 20SWG 300 X 300MM SQUARE 0.9MM THICK | eBay

It can be cut by scoring with a sharp knife if that's all you got...

[Sea Chief]

The way Sea Chief sells it he lives at Ice Station Zebra for all purposes related to commerce and materials, yet so close to stodgy neighbors that he can't crank his amps. I don't dispute this, but I don't know of any other place where lots of people live without resources

No ChuckH, I live in a stupidly expensive village (as most are in the sth of england now) & every brick is worth £stupid: I therefore have to live in extremely close proximity to the next person. The village is fairly remote. There are quite alot of people here, without so much as a village shop.. understand?

There is one local recycle centre who dont let you touch anything thats thrown (health & safety), Ive scoured my home/ sheds here, scoured ebay. I cannot find any sort of bendable sheet of metal or aluminIum or any cutting tools to fashion anything larger down to size should I find anything. Damned annoying as all the components sitting here. The only thing I can do is make use of a small pedal aluminIum box, somehow cut some more holes in this, somehow cut out a large section of the base as the rheostat is so tall, then somehow mount it onto something: just not possible.

[Chuck H]

EBay is not a good source for sheet metal of any kind because it's "often" ..... um ...... thin, flat, and ..... large ..... usually measured in feet.
You can't put it in an envelope or shoebox and mail it .

I suggest you look around your own home, or in garbage dumps or at a local recycling spot or ask some guy who makes aluminum doors and windows, for scrap aluminum pieces.

2 blocks away I have these guys who do long distance buses bodywork (think Greyhound) and they are junking large side panels every week.
Partly bent or crushed, that's why they replace them, but with large sections intact, enough for quite a few amp chassis or panels, they usually pile them to sell to aluminum recyclers, I just go through the pile and get what I need for beer money ... or actual beer bottles

It may be a piece of sheet which you can score and cut with a utility knife or a piece of rail or extrusion which you cut with a hand saw, then file raw edges a little for neatness.

Aluminum is your friend if you take it slow.

Forget steel.

The way Sea Chief sells it he lives at Ice Station Zebra for all purposes related to commerce and materials, yet so close to stodgy neighbors that he can't crank his amps. I don't dispute this, but I don't know of any other place where lots of people live without resources

[J M Fahey]

EBay is not a good source for sheet metal of any kind because it's "often" ..... um ...... thin, flat, and ..... large ..... usually measured in feet.
You can't put it in an envelope or shoebox and mail it .

I suggest you look around your own home, or in garbage dumps or at a local recycling spot or ask some guy who makes aluminum doors and windows, for scrap aluminum pieces.

2 blocks away I have these guys who do long distance buses bodywork (think Greyhound) and they are junking large side panels every week.
Partly bent or crushed, that's why they replace them, but with large sections intact, enough for quite a few amp chassis or panels, they usually pile them to sell to aluminum recyclers, I just go through the pile and get what I need for beer money ... or actual beer bottles

It may be a piece of sheet which you can score and cut with a utility knife or a piece of rail or extrusion which you cut with a hand saw, then file raw edges a little for neatness.

Aluminum is your friend if you take it slow.

Forget steel.

[Chuck H]

What he said ^^^^^^^^^^^^^^^^^^^^^^^^^

It will seem a little flimsy in sheet form, but the bends and mounting sturdy it up just fine. Be sure to get a little extra so you can experiment with the first bend. That way you won't be out of business if something goes wrong. Not that it will. It didn't for me and I was just winging it. I do have a little experience though because I use to bend aluminum flashing into parabolic lamp reflectors. If you do have trouble I found that a shallow score in the aluminum helped create a nice straight bend.

[guitician]

1100 Aluminum soft sheet is the easiest to bend. I use .040" inch thickness. I bend it like Chuck said, against wood, or clamped between two pieces of wood.

[Sea Chief]

That's them. Use the screw holes to attach them to an aluminum chassis of any sort (plate or box). I use a smear of thermal paste, but I don't think that's critical at all in this application.

Ok Chuck I'll go for 2 of these then. Also ebay seems a possible source of some alu sheet.

Can you tell me what thickness is good for bending, just, so theres still some decent structure/ stiffness.. rather like your piece sounds ideal thickness (forgive me if I ~follow your idea here.. Im hopeless at imagining how such things might be done w'out an eg).

Thanks chaps.

[Chuck H]

Are these the types you use, and are they designed to screw into anything in particular? 25W Arcol Aluminium Clad Wirewound Resistor 10R | eBay

That's them. Use the screw holes to attach them to an aluminum chassis of any sort (plate or box). I use a smear of thermal paste, but I don't think that's critical at all in this application.

[guitician]

If you look at this data sheet you can see that the added heatsink will give you added performance, but the dissipation for without a heatsink is listed too. Without a heatsink there is power de-rating. http://www.mouser.com/ds/2/32/Hs11-12.31-904.pdf