Pre amp chassis material

[The Dude]

Is there any advantages of using one over the other, other then weight when it comes to choosing the right metal such as either aluminum, or poweder coated steel.

Thanks

Duder.

[Marvel]

The aluminum won't cause problems with magnetic fields from transformers and high voltage AC wiring, and is a LOT easier to work. Making holes, drilling and filing steel is no fun unless you have all the right tools.

The steel chassis is more durable and can handle the weight of large trannies better.

[Chris A]

Is there any advantage of using one over the other, other than weight when it comes to choosing the right metal such as either aluminum, or powder coated steel...

Aluminum, depending on the alloy, has much better thermal conductance (10-16 times as great as stainless steel). Also, aluminum is usually thicker since it's density in much less than steel making it less prone to elastic deflection when used in flat plates.

Aluminum also isn't ferromagnetic, as mentioned above, so if there are external magnetic fields around transformers there shouldn't be as much field distortion due to proximity to aluminum plates. However, since aluminum isn't ferromagnetic, it doesn't do much to containing any stray magnetic fields outside of the chassis, or external magnetic fields entering the chassis area.

Chris

[The Dude]

Marvel, Cask,

Maybe this would help, project is a tube preamp. So should I stay away from steel, from the sounds of things that is what you are saying. Is there a product that can line a steel chassis that would help with magnetic fields. Somes times the technical stuff gets tuff to understand.

Thanks guys.

[tube fanatic]

Marvel, Cask,

Maybe this would help, project is a tube preamp. So should I stay away from steel, from the sounds of things that is what you are saying. Is there a product that can line a steel chassis that would help with magnetic fields. Somes times the technical stuff gets tuff to understand.

Thanks guys.

Use an aluminum chassis and either use tubes which are self shielding (such as metal jacket 6J5s, 6SJ7s, etc.) or use shielded sockets if you're going to use anything in the 12AX7 family. If the power transformer (and choke if you use one) is enclosed (as opposed to open frame), in combination with the tubes being shielded, hum should not be an issue from magnetic field saturation. It's imperative that you keep filament and AC wiring as far away from the input circuitry of the preamp as possible (or even build the power supply on a separate chassis and strap it over via a relatively short interconnect), very tightly twist the filament leads, adequately bypass the cathode resistor(s), and use star grounding (use a ground buss which connects to the chassis at only one point- the ground lug on the input jack is often a good spot.)

[The Dude]

Heres a link of what I have so far everything sounds great.

http://community.klipsch.com/forums/t/162837.aspx

I want to add the phono stage but as you can tell I don't have the room for it. Someone gave me the idea of building a seperate chassis for the power supply, which could easliy be done. If I was to go that route what guage wire would you use.

Thanks

Nick

[tube fanatic]

If you go with a separate power supply, are you going to supply everything with it, or just the phono board? In either case, a couple of feet of #20 should be just fine. Verify that the voltage rating of the insulation exceeds whatever B+ voltage is on the tubes (tightly twist the filament leads here also.) Set up a plug/socket arrangement so that it is not possible to accidentally come into contact with the B+ (i.e. socket on the power supply and plug on the leads coming from the preamp/phono preamp). A nice way to do this is with an octal socket and plug, or Cinch Jones sockets/plugs with the required number of pins.

[The Dude]

No the separate power suppy, would only be the power supply board, and transformer. If I go this route would I still need the aluminum chassis for the transformer, or could I then use a steal one for the power supply and just leave the line stage and phono stage in the aluminum chassis. Hopefully that make sense cause I know I have to think about it for a sec.

[tube fanatic]

Now I see how you want to do this. Yes, the best arrangement is for the phono and line stages to share the same chassis, with the power supply on it's own chassis. I would not be overly concerned about whether it's steel or aluminum (although as someone above said, drilling steel isn't fun!)

[The Dude]

(although as someone above said, drilling steel isn't fun!)

My old man is a television repairman, he's got this ultimate set of tools[H]

[tube fanatic]

(although as someone above said, drilling steel isn't fun!)

My old man is a television repairman, he's got this ultimate set of tools

Ah, now I can relate, having spent a huge portion of my life doing that myself! Learn everything you can from him as the practical knowledge acquired from doing that kind of work every day often surpasses what you can get from a book!!!

[mustang guy]

Copper in contact with aluminum can cause galvanic corrosion. I can see this as a potential problem when you are grounding your chassis, so some precaution should be taken there.