350V is Fender factory correct. These two caps are in series so, at 350@, you are dealing with a 700VDC capacitor. The SR is typically delivering 460VDC at this junction.

This resistor controls the blend of the non-reverb signal and the 10pf cap controls the amount of treble bleed. Both these values are important in that Fender R&D established the values. If you can't find a single resistor value, make a series pair... 2.2M and 1M? Just make sure you bridge both resistors with the 10 pf cap.

I don't think a 4.7M is a good idea. You have to remember that Fender really tweaked the values of the parts in these amps. In the case of the 3.3M resistor, you have to remember that this is the non-reverb guitar signal path to the PI. Yep, it passes through the 3.3M resistor and that 10pf cap is a treble bypass cap. If you want to ruin the sound of a Fender reverb equipped combo amp try a 50pf cap across the 3.3M. Virtually every part of the circuit has already been tweaked by the original designers, keep this in mind. My best advice: Find a 3.3M resistor.

I use the one that Andrea suggested and it works very well, no issues. A plus, it's smaller than the one that you used to use!

I also changed the 2nd tremolo cap to .02 (stock, it was .01) and this makes the tremolo Speed Control behave as I'd hoped. The very fastest speed is now slower (but still gets fast), which gives the Speed Control the kind of range that makes it easier to find a usable speed. It works for me. FWIW, I also think that some may want an even slower overall top speed so here I would go with a .03 1st cap and a .02 2nd cap. (And be aware, because the traces (front and back) are connected through the board holes, unsoldering a part to replace it is not an easy task, believe me. My board can be 'flipped up' to have the board sit at a 90 degree angle to unsolder a part if need be. (I use painter's masking tape to tape the board in the 90 degree position, btw. because the attached tube wires (#22) tend to resist the 90 degree band). To accomplish this without unsoldering the various connections, a ran a #14 copper bus wire across the back of my pots and made sure that the wires on the end of the board (the power supply end) are long enough to accommodate this manuever. This way, I can unbolt the pots and input jacks and keep things connected as a complete unit. Yeah, it's a bit of work, but things go back together quickly. All of which is to say, if you can, it's best to make a decision before the solder flows. :) Last thought, I am using a 3Meg reverse taper (Speed) potentiometer (exactly 3Meg) and there are 3M pots out there that only measure 2M. Measure your parts or you may be building something you aren't expecting.

I've spent more time with the circuit and sorted the noise/hum issue in the reverb. The amp is really a very Beautiful PR! I fixed my problem by changing Andrea's grounding path on the RCA jacks, and rerouting a few wires. I've passed this along to Andrea and he tells me he will update the PDF Layout. Here's and audio sample I made this morning.

Alright, I've tried this grounding path as described in the video and (of course) I do not have the benefit of the traditional Fender ground connections/path that the YT video poster had. I think the likelihood of this 'shotgun' approach working on this PC board is next to impossible but I tried. The result is a non-working reverb and a different kind of hum. I even reattached the reverb tranny ground back to it's original chassis ground point (as shown in your layout) and tried alligator cliping the ground bus wire (connected to the 3 RCA jacks) to various points on the PC's ground points. This was a futile endeavor. Doing so either created the original hum and voltage on the chassis that you heard in the recordings or a different hum and a non-working reverb. Q: Has anybody built a quiet PR using this circuit board?

I've looked at the link you listed. What he's done (based on - apparently - some MojoTone amp tech info) is odd relative to your build layout. First off, he lifts the chassis ground of the reverb tranny and attaches it only to the isolated ground of the reverb tank input RCA jack. Does this seem like a good move? The second thing he does is isolate the other 3 RCA jacks - left to right (reverb return/reverb 'on-off'/and tremolo 'on-off') and combines their chassis isolated grounds to one bus which he then attaches to the circuit board ground path that includes the 47 ohm NFB tail. Does this look like a good move? I find all of this a bit odd, but his reverb was definitely quieter than what I have so I will try this and report back.

Andrea, to see where these traces are going would be a help, YES. And btw, you never answered my earlier question: Am I supposed to be insulating the input jacks? from the chassis? Since the noise is not coming from there (sound sample without reverb) I don’t see this as something I need to do. Do you? Can you explain the apparent voltage I am getting on the chassis when the reverb return is connected to V3? Has anyone else built this particular board? You asked to hear the amp with the reverb tank disconnected. Here's a recording of that. In the recording, when I say 'I have the volume at 3 (the null point), I am refering to the REVERB volume pot. Eventually I start at '1' on this pot and turn it to '10'. The input Volume control is at '4' but it makes no difference where it is turned, the noise is completely from the reverb circuit.

I made two recordings on my phone to post here. The first one (the first half) has Pin 2 of V3 disconnected. This removes the Reverb return to the circuit. The second recording (second half) is with Pin 2 reattached to V3, same settings on the amp. Hopefully this might point out some obvious problem that i can't find.

Also, staying on the subject of grounding, the RCA jacks connecting the tank and the footswitches offer another 'double' grounding issue. The RCA jacks I'm using are grounded to the chassis and yet your diagram shows the addition of a ground point to chassis (that I added on my chassis, btw). Are you thinking that the RCA jacks should be insulated from ground and there should only be one ground path? At this point I DEFINITELY think there is grounding problem involving DC/AC voltage in my build. It is as if the circuit is not completely grounded somehow. My guitars (I have a few) exhibit that strange electrical vibration feeling as I lightly rub a grounded part of the guitar. Has anyone else finished this amp? I would love to hear some of your reviews. Andreas, earlier you mentioned that someone had an issue with the reverb RCA connections? Was there something there? I think it was a DR build, however, and not a PR.

Andreas, here is the Layout section that relates to the latest image you sent. Since my input jacks are attached to the chassis, the layout is - to me - suggesting two adjacent ground points. What am I missing? As you mention something about a single ground point, I think you are telling me that the ground point to the input jack should be removed. This is confusing? There are no instructions to mention the idea that the input jacks should be insulated.....

Andreas, hi. First off, I am a bit picky, it's true, and my concerns might never catch the ear of someone else. My chassis is 'open face' (no top cover) at this time, and this is where I typically trouble shoot a build. In other words, your board is installed in a Princeton Reverb (steel) chassis but not installed in a cabinet with shielded top cover. (And thank you again for a drawing, this is a help.) Another thought, since it is understood by most builders that the reverb is always the biggest source of potential noise in a guitar amp circuit, this is always a focus of mine. I can't help this because typically where most users won't turn the reverb above 3-4, I have sold Fender clones where the buyer calls me and tells me he/she is turning it to '10' and it's noisy. So, I focus on this. I have rerouted the V3 pin 7 wire to the front of the chassis (toward the control panel) and then turn it left, brought it over the top of the board at the two 'stacked' caps, added a 1.5K grid stopper resistor and attached it to V3 pin7. I think this sounds slightly better, but a shielded wire is going to be better still, so this is what I will do. You ask about proper grounding and yes, I have followed your plan to the letter with the exception of the PT ground point. Here I did what Fender did and soldered it to chassis in an area between the PT and the circuit board. This is also where I attached the PC board power supply ground, leaving the filament 100 ohm resistors attached to the closest PT lug and the AC cord ground wire attached to another lug at the rear of the PT. However, since I'm here, I wanted to ask you about the channel input cathode resistor and it's electrolytic capacitor? Why did you separate these two ground points? I've never seen this before. Is it some kind of failsafe? As to the first .01 cap in line after the initial .02 cap, I do think you should suggest to your builders that they may want to change this to .02 (before they install the board) if they want to have fuller range of tremolo speed. My Speed pot is truly 3M and it definitely needs more range. I'll post a video tomorrow.

I realize that I interrupted the 99tiller and his concerns by posting here. Sorry 99tiller! I reposted my questions regarding the Princeton Reverb board in the Trouble Shooting section. All my issues with the Princeton Reverb build have been resolved.

Also, regarding proper dress issues, there are some who feel that V2 pins 1 and 6 should be connected via a connecting wire that lays flat on the chassis and loops around the back of the tube socket, not a straight jumper across the tube socket. If you take a look at the Fender (PR AA1164) created layout you can see what I'm referring to.

I just noticed something that might need some attention. The PR didn't have a choke. Instead, originally it used a 1K 2W CC resistor that served as a choke. These would typically fail over time and need to be replaced, so it's nice to see a 3W resistor suggested here. However, a better choice might be a wirewound type 5W resistor that (because of the wire coil inside it) might offer a slight choke affect as well as a longer life. Antique Radio Supply/cedist.com offers a cylindrical version of said, but also the ceramic block type exists as well, both 5W. At this point, after the 1K 2W CC resistor (listed as 1W on the Fender Schematic) that Fender used (in their original design), Fender ran plain wire to the #4 pins of the 6V6s. Basically this 1K resistor replaced what Fender would typically accomplish with a 100 ohm choke and two 470 ohm 2W resistors in their more expensive amps, one being attached to either 6V6. So here, this PCB includes a place for the two 470 resistors that Fender didn't use in the original build. And this is something to consider. If you add the two resistors (along with the 1K resistor in the power supply), this will cause slightly less output from the amp and also a bit more 'compression'. This may or may not be what you want, so give the amp a listen when you get it completed. The other option, if you are looking for more headroom, beyond using just the 1K resistor, you could actually use a 100 ohm choke (as is found in a Deluxe Reverb, for example) and then add two 470 ohm resistors to pin #4 of the two 6V6s. Actually, this is probably what I will do, FWIW.

Waiting for mine to arrive right now, I have faith that it will be a quiet build using this PC board layout. Should be fun to build, too.