Consumer (audio) parts moved to plastic many years ago in all areas other than power
and some RF. There will be similarities between GP amplifiers like a BC108B, BC548B and
BC182B but when it comes to higher Vce ranges with complementary BC546/56
and MPSA42/92 etc. you will find few equivalents, if any, and may need to redesign
depending on your actual circuit requirements.
But this is a "high quality appearance" issue, no?
Or go all the way and pot the whole voltage stage. Keep certain aspects a closely gaurded secret ,and charge out the wahoo for them. One could also just paint them silver and classify them as mil spec. Aren't we awful ... no faith in audiophile "magic".
The best idea is actually a varient of the first one above , enclose the voltage stage in tin like a TV tuner module :
The RF can idea is a good idea as you can get those designed for PCB mouting - but utterly pointless, an amp will be in a grounded metal box, and RF pickup usually comes through the signal input (failing a proper RF stopper network on the input!)
We are not "at it again". Nagsy has just damaged his credibility by discounting the use of snubbers , emitter resistors , bringing unrectified AC to the amp board ... saying metal devices are better and "magical". This is not credible , pushes SOTA back a decade or so , and is just a subjective opinion .
For input stages ,SMD matched pairs are the next step :
For the differential or CM - this page :
The only metal can I would even consider is for the input , but then I would also consider cost/sourcing versus perceived/real performance gains.
Using TO-126's thermally coupled to a aluminum strip for any sane VAS , you can run them cooler or hotter with no worry , surviving the heat of the desert , jungle,hot bar- room , US southeast w/no AC !!
The only reason to design an amp all "metal can" in 2010 is to make the sourcing proprietary and to profit from this. The downside is that user will have a "brick" at a later date.
This why I hate USA style capitalism , to mislead the consumer is accepted and embraced here , to make things "look good" is more important than substance.
looks like a rehash of a rehash,,, go look at 2n3440/2n5415 Hafler used them in the vas of the DH200/DH220 and you can get cool little heat sinks for them. mouser p/n 532-323005800 aavid thermalloy for TO5...