Mojotone PR buzz

[dbaum]

I recently built a Mojotone PR kit. Amp sounds great but I have a load buzz that increases as I dial up the treble pot. It also gets more pronounced as I raise the volume.
I also have some hum on the reverb pot I’d like to kill.
I know this is an often chased topic, I searched but couldn’t find direct answers. I’m new to amp building so any point in the right direction would be much appreciated.

[PRR]

The treble-volume network is the most sensitive area in this amplifier. Fender and Mojotone route it away from all buzz sources: wall-power, heaters, B+ lines. Did you follow a known-good layout exactly? Pictures of that side of the and a link to the Mojotone product you have.

[dbaum]

I followed the Mojotone layout and referenced the stewmac layout along the way as well. I’ll post some pics of my amp and the layout I followed tomorrow.

[dbaum]

I found some very poor solder joints on the voltage dropping resistor on the cap can - another rookie error    I cleaned them up along with a few other marginal joints.  The buzz on the treble is gone until I hit 9 or 10 on the dial and then is very faint. An overall major improvement. 
I still have a lot of humm from the reverb.  I'll try reorienting the tank a little to avoid transformer interference and see where that take me.  Any other advice would be appreciated.
I'm also going to make most of the mods Rob suggests on his Princeton Reverb page while I'm in there.  Fingers crossed!

[PRR]

> I'll try reorienting the tank a little

Don't be timid. Get a lot of slack in the wires and move it all about. Remember Neil Young puts his springs _under the stage. That's more for mechanical feedback than hum reception, but it's the right attitude.

[jordan86]

Take this with a grain of salt, but every PR I’ve ever played adds a tiny bit of hum as you turn the reverb pot up. Every with the input volume down. “Tiny” is obviously subjective though, so chase it as long as you see fit.

[dbaum]

Thanks everyone. I assume some of the hum is normal but I'd like to reduce as much as possible.  Most of it is definitely coming from the tank location.  Moving it around makes a big difference.  Searching the sweet spot.
I also made most of the suggested mods on Rob Robinettes site -  added grid stop and screen resistors across the 6v6's, PI resistor, replaced voltage dropping resistors.  Still need to add the adjustable bias pot and swap the input jack resistors with metal film resistors.
I am very pleased with these mods!  It has really smoothed things out and sweetened the tone.  Couldn't be more happy!  Now searching for some sweet NOS tubes to replace the stock JJ's.

[Bieworm]

About the tubes...
Some might disagree, but the NOS thing is 99% hype. JJ's are just crappy tubes nowadays.  Some years ago they were fairly good, but since they marched up to being the most sold tube they are definitely way down in quality. I settle for tung sols and EHX nowadays. TAD are surprisingly good too. Heck, even those sovteks are better than JJ's

[texwest]

Thanks everyone. I assume some of the hum is normal but I'd like to reduce as much as possible.  Most of it is definitely coming from the tank location.  Moving it around makes a big difference.  Searching the sweet spot.
I also made most of the suggested mods on Rob Robinettes site -  added grid stop and screen resistors across the 6v6's, PI resistor, replaced voltage dropping resistors.  Still need to add the adjustable bias pot and swap the input jack resistors with metal film resistors.
I am very pleased with these mods!  It has really smoothed things out and sweetened the tone.  Couldn't be more happy!  Now searching for some sweet NOS tubes to replace the stock JJ's.

I like to put as far from the speaker as possible.