Fender Hot Rod Deluxe conversion to single channel AB763

[MikePR]

Hi guys i just finished my Hot Rod Deluxe Ab763 single channel conversion. Schematics included. Amp is working but want to see if the schematic is good or it can be improved more. There are 2 things i noticed: Slightly hum even with volume on 0 and I wish the loudest volume of it comes before the 3/4 on the volume travel. The stock Hot Rod felt louder before the conversion. Any thoughts?

[tubenit]

I don't see any concerns with schematic.  Can you post a couple of gut shots of the chassis build.

With respect, Tubenit

[MikePR]

Here

[MikePR]

Here

[MikePR]

Here

[MikePR]

Here

[MikePR]

The Project Started as a 3 Preamp tubes then decide for 2 and with remaining parts of a previous build.

[VMS]

just thinking out loud and no idea what direction it takes the amp, but have you tried 12ax7 tube as PI tube?

[VMS]

also have you tried chopsticking the wires close to the heater wires and i see one wire that is not connected to anything on the last picture?

[MikePR]

Good catch but when i removed the third pre amp tube that wire i forgot to remove from board. Is not connected to anything. 12ax7 in PI does not change hum nor volume issue. Did
The chopstick treatment but to no avail. This schematic i took it from the Deluxe Lite version
Which was for 6V6. Will that be the issue?

[VMS]

It is probably going to be cleaner amp with 6L6 tubes.


To narrow down the hum problem, does the hum stop if you remove the PI tube?

[shooter]

one of the major contributors to hum is lead dress and proximity to things that are humming;

here's a pic I stole from Sluckeys 5E3 build.  Notice his filament wires in relation to signal, ground and vdc wires.  V1 is very susceptible to interference, both inside and OUTside the chassis

[Willabe]

This might be a problem. Speaker jack switches.

[MikePR]

I did not touch those. They are the stock Hot Rod Deluxe ones.  Do you recomend replace or islolate them from chassis?

[MikePR]

Well I removed the external speaker jack and isolated the main with nylon washers and still the hum. Decide to get a fiberboard with eyelids and start all over to make a cleaner board. Will keep you posted. Thx for the help.

[tubenit]

FWIW,  some of my first builds were somewhat "messy" & I have always found it worth while (when something didn't work) to redo it and try to get it "neater".   The layout and lead dress and good wiring  (neat & reasonable short runs) can make a big difference in tone.

with respect, Tubenit

[Willabe]

I did not touch those. They are the stock Hot Rod Deluxe ones.  Do you recomend replace or islolate them from chassis?

Depends on how the switches are wired up. On most Fenders the main speaker jack switch is shorted to ground with NO jack plugged in. Both your speaker jacks are shorting jacks and it looks like 1 of them has 2 switches on it.

That 2nd shorting jack might be wired to a tap on the OT for a different ohm when plugging into both speaker jacks.

I wasn't referring to them causing hum/noise.

[MikePR]

Here it is now. No Hum, silent as a baby's butt.  . Thx for the help guys.

[MikePR]

More pics

[vitruv]

Hi,  Nice Post !!

I'm thinking to convert my old blues deluxe into PTP design. I was a bit disappointed by the AB763 that is worse as a pedal platform than my deluxe to me. However your simple is really attractive. Can you tell us more about the sound? Is it close to a HRD or more to a deluxe reveb ?
What is the impact of having 2 instead of 3 stage preamps?
thanks, Vitruv