Blackvibe in a Princeton-sized chassis: Check my chassis/layout

[aguynamedben]

Hi, I'm new here. This is also my first amp build, so sorry if I'm asking something dumb.

I'm building Rob Robinette's Blackvibe as my first amp. Rob has a DIYLC file and instructs people to use a AB763 Pro chassis because the tube/PT holes are already there. But I live in a tiny apartment in San Francisco, so I'm going for a 1x12" Princeton combo sized Blackvibe.

Here's the layout: https://imgur.com/a/WeQc2tO (I used a Sketch and carefully translated all sizes from inches at a 72 pixels = 1 inch ratio.)
Here's Rob's original layout: https://robrobinette.com/images/Guitar/ ... _small.png

I'm going to order a custom chassis and want to make sure the power transformer cutout is in the right place. I also might have the chassis builder put the tube holes in.

Does the attached layout make sense? The main changes is I've moved the Bias & Balance board off to the left. Will that create noise because there are longer runs between that and the turret board?

Other questions:
* Does the orientation of the PT make sense?
* Should I have the chassis builder put an IEM cutout in the back left? (i.e. near the rectifier)
* Did I screw anything else up? Anything that will create noise?
* What is most likely to make this "Blackvibe in a Princeton-sized chassis" project fail? (aside from it being my first build in general...)
* Do you have a favorite custom chassis shop?

Thanks for any input, I really appreciate it an am excited to become part of this community.

Ben Standefer

[Stevem]

One issue I see it that your power transformer was made B+ current wise to power 2 more preamp tubes, and the result of this will be a plate voltage level on your preamp tubes that may make for a brittle sounding top end.
In regards to that first preamp tube I would get the amp up and running as is and then see if you want to up the value of that 4.7K resistor in the power supply such that your first preamp tube has no more then 225 volts on its plates.

Also ground wise the power amp screen filter needs to be run seperate to ground and this in turn means the collection of the rest of the grounds up thru the preamp section off of the board will be seperate also.
You will end up with a semi start grounding set up which will be a good starting place to tweak from for low 120 HZ hum.

[mirage_indigo]

>>* What is most likely to make this "Blackvibe in a Princeton-sized chassis" project fail? (aside from it being my first build in general...)

I've got two amp builds under my belt. My second project was a BF princeton reverb preamp into a tweed power section. Worked great; you'll love it.

I find I often underestimate mechanical issues (ie: getting things to fit, making sure holes are correct) One thing I now do is fit all the parts first to make sure they do indeed actually fit before I start soldering anything. I've had a couple near misses where I prewired a board outside an amp and then realized the clearance wasn't there to get to the far side of a filter cap or somethign similar. (it doesn't help I use Solen fast caps in my supplies). Pay particular attention to pot lug directions wrt to rotation.