Revisit #0183 with 5-piece chassis

[ijedouglas]

Cab I just finished

PXL_20231119_003212858.LONG_EXPOSURE-01.COVER.jpg

[Aaron]

Wow, great build! Beautiful work!

[ijedouglas]

Wow, great build! Beautiful work!

Thanks Aaron

[gonzomode]

Very impressing build! Possibly you can‘t go further in terms of cloning..
There seem to be an additional grounding point for the loop jacks. What‘s the difference in grounding them at this spot?

[Mr. dB]

Very tidy

[ijedouglas]

Very impressing build! Possibly you can‘t go further in terms of cloning..
There seem to be an additional grounding point for the loop jacks. What‘s the difference in grounding them at this spot?

Thank you.

I am not sure of the effect other than it possibly eliminates a ground loop at the EFX send/return. I copied this directly from an original specimen just a few serial numbers earlier than #0183 and based on everything that I can see and match up between that amp and the pics I have of #0183, they are pretty much identical in wiring and layout. Both send/return jacks are isolated and there is a separate ground wire for each running to that ground point

[Reeltarded]

Dumble lives.

That is MOST impressive!

[award70]

I understand that that's how HAD did it but aren't the fx send/return jacks already grounded via the chassis? I can not understand why an additional ground would do anything except create a ground loop. Maybe the jacks are isolated from the chassis? Not a criticism, just wondering.

Alan

[martin manning]

I am not sure of the effect other than it possibly eliminates a ground loop at the EFX send/return. I copied this directly from an original specimen just a few serial numbers earlier than #0183 and based on everything that I can see and match up between that amp and the pics I have of #0183, they are pretty much identical in wiring and layout. Both send/return jacks are isolated and there is a separate ground wire for each running to that ground point.

If both jacks are grounded there I don't see how it would break a ground loop or be any different from using standard non-isolated jacks, except it eliminates intermittent/noisy ground issues in a place where there will be a lot of plugging and unplugging going on that might loosen the bushing nuts. Super nice looking build! I'm definitely partial to the traditional eyelet board construction.

[ijedouglas]

Dumble lives.

That is MOST impressive!

I'm not so sure about that but thank you

[ijedouglas]

I understand that that's how HAD did it but aren't the fx send/return jacks already grounded via the chassis? I can not understand why an additional ground would do anything except create a ground loop. Maybe the jacks are isolated from the chassis? Not a criticism, just wondering.

Alan

"Both send/return jacks are isolated and there is a separate ground wire for each running to that ground point"

[ijedouglas]

I am not sure of the effect other than it possibly eliminates a ground loop at the EFX send/return. I copied this directly from an original specimen just a few serial numbers earlier than #0183 and based on everything that I can see and match up between that amp and the pics I have of #0183, they are pretty much identical in wiring and layout. Both send/return jacks are isolated and there is a separate ground wire for each running to that ground point.

If both jacks are grounded there I don't see how it would break a ground loop or be any different from using standard non-isolated jacks, except it eliminates intermittent/noisy ground issues in a place where there will be a lot of plugging and unplugging going on that might loosen the bushing nuts. Super nice looking build! I'm definitely partial to the traditional eyelet board construction.

Thanks Martin.

Both jacks are isolated. I'm sure there is a really good reason that HAD went to the trouble of a separate ground lug, isolated jacks and separate ground wires

[Blacksto99]

Beautiful work!
I have built several 5-piece chassis, and found that one had a noise problem, so I isolated the jacks and the noise problem was solved. I'm guessing there may be contact resistance between the panel and base plate.

[ijedouglas]

Beautiful work!
I have built several 5-piece chassis, and found that one had a noise problem, so I isolated the jacks and the noise problem was solved. I'm guessing there may be contact resistance between the panel and base plate.

Thank you.

That makes more sense that he was grounding it to the baseplate. In the real Dumble he still grounds the speaker jack to the chassis (back panel) as well as the safety ground which I copied in both of the last amps I built. I did tighten those chassis bolts like my life depended on it and checked all ground points between baseplate and panels and there was zero resistance.

[martin manning]

That makes more sense that he was grounding it to the baseplate. In the real Dumble he still grounds the speaker jack to the chassis (back panel) as well as the safety ground...

That makes a lot of sense, but why not take the same approach for the safety ground and speaker (OT secondary ground)? Maybe HAD's loop and input jack treatments were also a fix for a noise problem?