Hi all 🙂,
I'm building another tube amp after the 10-year hiatus (lockdown does horrible things to people, revivng the hobbies long dead), and this time I'd like to make it more user friendly than my previous builds.
It's a classic stereo point-to-point wired PP amp with fixed bias (with 4 separate pots and 4 typical current measurement resistors between cathodes and ground). So I need to make 4 test points (plus 1 or 2 for the ground) somehow, and I'd like them to hold multimeter probes reliably for having my hands free. And probably another 4 test points for measuring bias voltages to be able to match the output tubes using just the amp itself.
So, obvious options are:
1. External tip jacks and exposed pot shafts in the style of many guitar amps. Obviously the most convenient option, but not the most practical in terms of build (lots of chassis area covered in holes, sub-optimal pot placing, etc.)
2. Some kind of dedicated inner test terminals (isolated panel with tip jacks? dedicated turret/lug strip?). I don't mind flipping the amp once in a while, but the space inside the amp is tight, so I need the most compact solution possible.
3. Some "test extensions" (pieces of thick solid wire?) added to the test points (tube socket pins and ground), sticking above the rest of components. Simple, cheap, sounds stupid and unsafe.
4. Using hooked probes directly on the measuring points and just don't bother.
What do you think? What do you use? Any ideas are welcome.
Thanks!
I'm building another tube amp after the 10-year hiatus (lockdown does horrible things to people, revivng the hobbies long dead), and this time I'd like to make it more user friendly than my previous builds.
It's a classic stereo point-to-point wired PP amp with fixed bias (with 4 separate pots and 4 typical current measurement resistors between cathodes and ground). So I need to make 4 test points (plus 1 or 2 for the ground) somehow, and I'd like them to hold multimeter probes reliably for having my hands free. And probably another 4 test points for measuring bias voltages to be able to match the output tubes using just the amp itself.
So, obvious options are:
1. External tip jacks and exposed pot shafts in the style of many guitar amps. Obviously the most convenient option, but not the most practical in terms of build (lots of chassis area covered in holes, sub-optimal pot placing, etc.)
2. Some kind of dedicated inner test terminals (isolated panel with tip jacks? dedicated turret/lug strip?). I don't mind flipping the amp once in a while, but the space inside the amp is tight, so I need the most compact solution possible.
3. Some "test extensions" (pieces of thick solid wire?) added to the test points (tube socket pins and ground), sticking above the rest of components. Simple, cheap, sounds stupid and unsafe.
4. Using hooked probes directly on the measuring points and just don't bother.
What do you think? What do you use? Any ideas are welcome.
Thanks!
Mini banana jacks are nice.
Miniature Banana Jack | Pomona Electronics
If you put them in a place where you can stick your meter probes in, then just let them sit there while you adjust bias, then you get hands free operation.
You could also just build in ammeters so you don't need to use a DVM at all.
Miniature Banana Jack | Pomona Electronics
If you put them in a place where you can stick your meter probes in, then just let them sit there while you adjust bias, then you get hands free operation.
You could also just build in ammeters so you don't need to use a DVM at all.
You could also use a miniature digital voltmeter with a 4 position switch to measure the voltage across your 10 Ohm resistors. This will indicate the current. They don’t take much space and are very cheap in the Far East.
Regards, Gerrit
Regards, Gerrit
Yes, but ten of them... Maybe I can find the place fot them inside the amp though.
And unfortunately the chassis is quite small, so I don't really have place for switches and dedicated meters. Separate DMM it must be.
I like that idea, thank you! I've completely forgotten about the existence of multi-pin connectors...
Thanks, that definitely looks better than my idea of sticking wires 🙂