[Paul Ruby Amplifiers]
tube amplifier circuit boards
for diy amp builders
homeruby amplification
home page
servicesruby amplification
service offerings
productsruby amplification
product offerings
tagboardsruby amplification
custom services
partsamplifier parts
stocked for sale
yard saleamplifier parts
that gotta go
contactcontact ruby amplification projectsassorted
diy projects
linksother great diy
web sites
tech infotech info for
diy builders

jtm45 tagboards

NOTE: I no longer offer unstuffed tagboards. I will only make complete boards, with parts. The following considerations are provied as info. I will not make you an unstuffed board. This is one example of a stuffed and mounted board for a JTM45-RI.


In order to create a layout you like, you MUST consider the following.

Will you be using modern resistors?
The original JTM45 turret spacing across the board is too far for modern resistor lead length. Turrets must be pinched in for resistors to reach.

Do you want separate turrets for the input tube cathode resistor and bypass cap?
With them separate, you can then easily add a second resistor and cap to separate the bias control of the two input triodes.

Do you want the 68K input mixing resistors (input stage grid resistors) on the board or on the input tube socket?
I like to mount input resistors on a terminal strip right at the tube socket for maximum noise immunity. I use shielded line from there to the input jacks.

Do you want the power tube screen resistors moved onto the board?
This is easy to do and is how I like to wire my own but the original has the screen resistors mounted on the power tube sockets.

Do you want 5.6K grid resistors added to the board for KT66 power tubes?
These are a good idea to avoid oscillations.

Do you want bias control via a trimmer pot mounted to the board?
This is also not part of the original circuit but is useful to try out various power tubes.

Are you using an LCR 16x16uf filter cap for the preamp?
The original JTM45 had a dual can cap on the board but these are no longer available that I know of.

Do you intend to use Graydon's chassis?
Graydon's mounting holes match the original JTM45 layout exactly. Also note that Graydon's chassis will only accomodate a board of 11.5" total length. This limits other options that increase board length. Check out the jtm45 group to learn more about Graydon's chassis.

Do you want the wire through-holes on the board?
In the original wiring, Marshall used the extra holes to fish wires through to any turrets spaced away from the board edge.

top | home
ruby amplification is not associated with ruby tubes
content & layout copyright ruby amplification 2002
all rights reserved