D-Lite Trimmer Identification and Suggested Settings

[professormudd]

Greetings,

I've been completing the assembly of this old kit and I am just about ready to power it on. I have some questions regarding the trimmers that are in this amplifier.

I have attached the photo of the board and labeled the trimmers A, B, C, and D. I have also included the only piece of documentation I have for this amplifier, the printed layout.

I am hoping you might be able to help confirm or correct my assumptions regarding the use of these trimmers.

A: Preamp boost?
B: Mid boost?
C: ???
D: OD?

Thank you in advance for helping me identify these.

I understand I will have to fiddle a bit, but any advice on how to approach setting these is also appreciated.

[pompeiisneaks]

I've not seen pots on A or B before so I'm unsure

C is the OD input trimmer. This is how much raw signal goes into the drive channel from the first channel. there are multiple threads discussing how to set it optimally, but you can do it somewhat by ear as well just by setting the od volume and od drive at max and then dial it down to the right level of drive you'd like at max, then when you lower the drive/drive vol you'll get it more 'tamed' as you go.

D is the PI balance pot. It allows you to balance the PI perfectly or imbalance it for best 2nd order harmonic depending on your preference.

~Phil

[martin manning]

You've got C and D reversed, Phil. C is the PI balance and D is the OD entrance.

The 1M trimmer on the relay board (right side, B) is a variable PAB lift, and the 250k (left side, A) is a Vox-type cut control which is on when PAB is off.

[professormudd]

D is the PI balance pot. It allows you to balance the PI perfectly or imbalance it for best 2nd order harmonic depending on your preference.

Is this set by ear, or measurement? Do you recommend any particular procedure?

[pompeiisneaks]

There are many different ways to do it, there are multiple threads that show it, I've done videos on one way to do it, which you can watch here:



Hope that helps, but again this is just ONE way to do it.

Some prefer looking at the output of the power tubes to get the type of balance/imbalance at the output side, since power tubes can also be mismatched somewhat, etc.

~Phil

[pompeiisneaks]

You've got C and D reversed, Phil. C is the PI balance and D is the OD entrance.

The 1M trimmer on the relay board (right side, B) is a variable PAB lift, and the 250k (left side, A) is a Vox-type cut control which is on when PAB is off.

Yup you're right, my apologies

Thanks for the info on those other pots, not seen that in a d build yet, but I've definitely not seen them all!

~Phil

[martin manning]

Is this set by ear, or measurement? Do you recommend any particular procedure?

https://ampgarage.com/forum/viewtopic.php?f=4&t=18048

[professormudd]

Thanks guys. Wish me luck.