If it's any help, I just finished a TubeLab Simple SE with the layout as shown. The layout itself is dead quiet - no hum whatsoever. Twisted the filament connections (standard) and have relatively long input cables (coax, one end grounded) to the volume control and twisted-pair (again, only one end grounded) to the input 12AT7 triodes.
No ground lift, taking the output speaker connections to chassis at a star-ground location (along with the input RCA grounds and volume control ground).
Power transformer is on the top-side of the chassis, the Triad choke and output transformers mount inside the chassis. Chassis proper is a re-purposed NABU case, about 10 inches x 18 inches x 3 inches high - plenty of real-estate to lay out the parts.
I was quite worried about hum in this configuration, but it is absolutely quiet- no hum whatsoever. Been listening to it for over a week now, and very satisfied with the placement.
There is hope... And if not hope, at least informed troubleshooting!
~ Sam
No ground lift, taking the output speaker connections to chassis at a star-ground location (along with the input RCA grounds and volume control ground).
Power transformer is on the top-side of the chassis, the Triad choke and output transformers mount inside the chassis. Chassis proper is a re-purposed NABU case, about 10 inches x 18 inches x 3 inches high - plenty of real-estate to lay out the parts.
I was quite worried about hum in this configuration, but it is absolutely quiet- no hum whatsoever. Been listening to it for over a week now, and very satisfied with the placement.
There is hope... And if not hope, at least informed troubleshooting!
~ Sam
M Gregg,
it is going, but it is going a little slow at the moment - the thesis isn't finished yet and it has higher priority...
Currently I am planning to take the test setup to a friend of mine who is professionally doing audio stuff and owns the test equipment to characterize my build, gain, frequency response, THD and so on. I will not continue building before these measurements in order to be sure that no large changes have to be made to the design.
Concerning the chassis question, I changed my former approach a little, taking into account different ideas that have come up in this thread: The large chassis plate as a mechanical base remains, but it gets only large, rectangular cutouts where the rectifiers, driver stage and output stage are located.
Smaller and thinner plates then carry the valve sockets, standoffs and components for these subcircuits. These plates will be mounted with spacers (5-10mm) above the main chassis plate, allowing additional air flow.
The changes do not only make the machining of the main plate cheaper, but also allow subsequent changes to the circuit. If I decide for another driver/output stage later, I only have to change out the small plate carrying it...
Pictures will follow later, still have to draw the plates of the left channel.
Regards,
Rundmaus
Thats Great...yes modular design and cost also speed of update and less re-tooling required. Machine tools also last longer working on reduced thickness/weight of shipping etc etc if it was a time and work study then you can machine several thinner plates at one time...If it was a production piece thats how industry would see it. The other thing would be ease of repair..Good luck with the thesis...
Regards
M. Gregg
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