I've started building an amplifier in a very backwards fashion. I designed the chassis first (assuming it would be a small amp) and have waited for a suitable schematic to present itself to me
Redboy reminded me of a design I had seen years ago as a subscriber to Sound Practices, the J.C. Morrison "Micro". The Micro is a SE 2A3 amp that uses no coupling capacitor between the driver stage and output tube. Just two tubes and a transformer in the signal path! I fell in love with this years ago but had forgotten about it. I knew when I saw it that it was the amplifier to go in this chassis.
I'm building this amp a little differently than any other I have in the past. Typically builds have consisted of everything being mounted to a metal plate. This works well because it is easy. I'm not sure that, mechanically, it is a good idea to have everything on the same plane. For instance, power transformers have a tendency to vibrate and tubes are microphonic:scratch2:
I decided to mount the transformers on a very heavy, dead plate made from 1.25" Paperstone. This material is similar to Corian and other solid surface countertop materials in that it is extremely dense and relatively inert. As you might have guessed, Paperstone is made from highly compressed paper with an epoxy binder. It is extremely close to Phenolic, in my experience.
The top is a a roasting pan of .125" thick aluminum. In this instance it is acting as more of a cowl to cover the electronics and protect curious fingers from sudden death. It attaches at two points (the center hole at each end where the original handles were riveted) to the plinth via threaded fasteners in paperstone blocks.
Machined brass banana jacks rescued from some old stacking plugs I had make up the speakers connections. Other connections will be flush mounted as well, I don't like anything to stick out and get broken off.
The sockets for the 6SL7's and 2A3's will be mounted to an aluminum plate mounted to standoffs machined from the same material. I made a dress plate as well that will go on top of the aluminum and cover the fasteners. This shows the approximate position on the chassis, although it will be beneath the pan.
So there you go. I will be looking for recommendations on iron or any other part of this you have an opinion on! In an amplifier this simple I believe, to quote Depeche Mode, "Everything counts in large amounts"
Redboy reminded me of a design I had seen years ago as a subscriber to Sound Practices, the J.C. Morrison "Micro". The Micro is a SE 2A3 amp that uses no coupling capacitor between the driver stage and output tube. Just two tubes and a transformer in the signal path! I fell in love with this years ago but had forgotten about it. I knew when I saw it that it was the amplifier to go in this chassis.
I'm building this amp a little differently than any other I have in the past. Typically builds have consisted of everything being mounted to a metal plate. This works well because it is easy. I'm not sure that, mechanically, it is a good idea to have everything on the same plane. For instance, power transformers have a tendency to vibrate and tubes are microphonic:scratch2:
I decided to mount the transformers on a very heavy, dead plate made from 1.25" Paperstone. This material is similar to Corian and other solid surface countertop materials in that it is extremely dense and relatively inert. As you might have guessed, Paperstone is made from highly compressed paper with an epoxy binder. It is extremely close to Phenolic, in my experience.
The top is a a roasting pan of .125" thick aluminum. In this instance it is acting as more of a cowl to cover the electronics and protect curious fingers from sudden death. It attaches at two points (the center hole at each end where the original handles were riveted) to the plinth via threaded fasteners in paperstone blocks.
Machined brass banana jacks rescued from some old stacking plugs I had make up the speakers connections. Other connections will be flush mounted as well, I don't like anything to stick out and get broken off.
The sockets for the 6SL7's and 2A3's will be mounted to an aluminum plate mounted to standoffs machined from the same material. I made a dress plate as well that will go on top of the aluminum and cover the fasteners. This shows the approximate position on the chassis, although it will be beneath the pan.
So there you go. I will be looking for recommendations on iron or any other part of this you have an opinion on! In an amplifier this simple I believe, to quote Depeche Mode, "Everything counts in large amounts"
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