C-lator hum

[dbharris]

1. This is built and assembled by Ceriatone. I did see that the paint was removed for the one lug I did loosen. Can check the others.

2. I can not see what's wrong with the PS ground wiring. I think they match Ceriatones layout, also in accordance to other layouts I've seen, but I can't see where I'm wrong. Could you be more specific? Thanks

The mains ground should be by itself. The first power cap ground goes to its own location and the second power cap ground goes to the star between the pots and the PCB. Check the layout in the files section.

-Dan

Move the ground wire of the 33 uF to the star between PCB and pots, while keeping the 47 uF at its current location together with the AC inlet ground point? Can try that tomorrow.

Almost. You need to add an additional ground point for the pair of 47 uf caps. Probably a few inches from the safety ground will be fine. Yes, to moving the 33 uf caps.

[ynor]

The mains ground should be by itself. The first power cap ground goes to its own location and the second power cap ground goes to the star between the pots and the PCB. Check the layout in the files section.

-Dan

Move the ground wire of the 33 uF to the star between PCB and pots, while keeping the 47 uF at its current location together with the AC inlet ground point? Can try that tomorrow.

Almost. You need to add an additional ground point for the pair of 47 uf caps. Probably a few inches from the safety ground will be fine. Yes, to moving the 33 uf caps.

I can't wait to try this when I get the opportunity later today!

Would you expect any troubles if I use this location for the 47 uF grounding? Will remove the paint, but hope to use an existing hole in the chassis.

Screenshot_20240315_070440_Gallery.jpg

[martin manning]

Two circuit ground locations, rectifier/reservoir (most important to tie those together directly) and everything else, plus a separate earth safety ground (if you're doing it strictly by the book) should be sufficient. This layout (see .pdf) is quiet: https://ampgarage.com/forum/viewtopic.p ... 34#p170734 Note that tthe jacks are not isolated, but the front and rear panels are floating, and do not make good contact with the powder coated main shell.

[ynor]

Two circuit ground locations, rectifier/reservoir (most important to tie these together directly) and everything else, plus a separate earth safety ground (if you're doing it strictly by the book) should be sufficient. This layout (see .pdf) is quiet: https://ampgarage.com/forum/viewtopic.p ... 34#p170734 Note that tthe jacks are not isolated, but the front and rear panels are floating, and do not make good contact with the powder coated main shell.

Thanks, thats great. The C-lator appears to have a different rectifier circuit than the bridge rectifier on your build if I'm not mistaken, but I think converting your ground layout to the C-lator translates to: (Rectifier) and 47 uF reservoir cap to G2, earth safety ground to SG, and everything else (including the 33 uF filters) to G1. Which is excatly what you said.

[martin manning]

Original D'lators had voltage doubler rectifiers. I don't know what your C-lator uses, but the principles are exactly the same.

[ynor]

The schematics for the C-lator is like this one: https://ampgarage.com/forum/viewtopic.php?t=34081

Isn't that a Delon bridge voltage doubler?

[martin manning]

Yes, and it is a full wave rectifier. I'm left wondering why C-tone sold something that would have a hum problem.

[ynor]

Me too. I will try your corrections on this layout design and let you know.

[ynor]

So I moved the grounds as in the picture. Sorry to say nothing changed. The hum is still there. The hum is not loud, but still very annoying at living room levels. I don't think the C-lator should inject any hum at all into the fx loop of the amp, but maybe I have too high expectations?

20240315_174113.jpg

[dbharris]

Maybe try moving your solder tab under the bracket for the PCB?

-Dan

[martin manning]

I would not expect any significant increase in hum when the C-lator is plugged in. You said the hum is 50 Hz, and it is still there when he C-lator is in standby, so it must be on the C-lator transformer's primary side or it's heater related.
Have you tried changing the tube?
What happens if you remove the tube?
What happens if you remove the send cable or the return cable?
Are you sure you have a good heater ground reference?

[ynor]

I would not expect any significant increase in hum when the C-lator is plugged in. You said the hum is 50 Hz, and it is still there when he C-lator is in standby, so it must be on the C-lator transformer's primary side or it's heater related.
Have you tried changing the tube?
What happens if you remove the tube?
What happens if you remove the send or return cables?

Yes, likely that it is related to the C-lators AC power. It is 50 Hz, with harmonics, so the 150 Hz is the most prominent according to my phones mic spectrogram.

Did not change the tube, but did remove it and hum is the same running without the tube.

Also, removing the send/return cables does not remove the hum. Signal is then running straight through from send to return jack. But when one jack is plugged in either send or return (loop interrupted) the hum is slightly reduced if I remember correctly. Makes be believe the hum is injected into the signal path somewhere?

[ynor]

Maybe try moving your solder tab under the bracket for the PCB?

-Dan

Yes that would be a better connection with the chassis. Don't think it is essential though as the hum isn't reduced in any way after separating the grounds. But will move it under the bracket as you suggest.

[ynor]

Are you sure you have a good heater ground reference?

Absolutely not. How can I exclude that as a cause?

[ynor]

power transformer is inserting it in the chain.. or bad filtering.. maybe remount transformer totally to the end in right direction, but in fist place measure with ocilloscope residual humm in each Ub+ node

I can feel the need for one of these growing...

Screenshot_20240315_195515_Gallery.jpg