plastic or metal

[bdm47]

are their any benrfits using acylic plastic instead of aluminium to make amp case. i have plenty of 6mm .putting 405 clone case cheers bernard

[vacuphile]

Safety!

[bdm47]

thanks for the reply i was hoping plastic may offer a better sonics ??? any views 405 clone cheers bernard

[vacuphile]

Sonics is about what you put inside the box.

[bdm47]

agreed .denis moorcroft dnm guru reckons acylic has sonic values . i have a dnm series 3 twin pre amp acrylic case cheers bernard

[DF96]

A non-conducting case is likely to let in more RFI, so potentially has worse 'sonics'.

[davidsrsb]

DNM would have disagreed with that. They used plastic casings.
Safety is not the reason - CRT TVs were usually plastic and they contained mains and 25 KV EHT
I suspect that the real reason most commercial amps are metal is heatsinking.

[pinkmouse]

As this is a diy site, why not try both and see what you think?

[Centvrion]

It's all about Faraday-Lenz-Neumann law. Understand it, than you'll understand what is better for you. Personally I like MDF cases.:-P

[DF96]

Originally Posted by davidsrb

DNM would have disagreed with that. They used plastic casings.

I guess you mean statements like this (from their website)

Originally Posted by DNM

Vitally important for high fidelity, the form and materials used in the construction of any amplifier affect its sound as much as its circuit diagram. Amplifiers have many connecting tracks interweaving across the circuit boards and these interact magnetically with each other and with the electronic components. A magnetic haze, generated by the signal, interacts with the amplifier in a complex way destroying sound fidelity and the metal casework normally used further modifies the magnetic fields to produce dynamic compression.

There is a grain of truth in this, but I regard it as being mainly advertising copy rather than engineering principles. Current paths do interact magnetically, although only weakly in a good design (small loop areas etc.). These fields will reach the case, although only weakly, and the case will affect them - even more weakly. If you have a plastic case then the fields will interact with whatever is outside too. Similarly for aluminium. Dynamic compression is most unlikely - for that you would need strong magnetic fields and probably a steel (or other ferromagnetic material) case tightly coupled to the circuitry.

More likely is that they decided that transparent cases look nice (e.g. early Apple Macs?) and then had to come up with a 'sound' argument to support this. Hopefully they include some RF low pass filters to stop broadcast, cell-phone and WiFi stuff from getting in.