Fender Princeton Reverb Build w/ Heat Blued Steel Chassis

[nsabatelli]

Hi, I just finished building a AA1164 Princeton Reverb and I wanted to share the results of some experimenting and learning I did along the way. I got the idea to use heat bluing as a decorative effect from watchmaking. You commonly see blued hands and screws and I think they are beautiful and I wanted the same for my amp.

I ended up using my regular kitchen oven set to self cleaning mode to get it as hot as I could, I was hoping for 550F ish but I didn't really have any idea what temp the self cleaning cycle actually hit. I left my bare steel chassis in for about 45 minutes to allow the steel to fully come up to temperature. The result was a deep purple color that I was really happy with! I applied a clear coat that I wet sanded and polished to get a nice glossy surface finish that made the purple pop.

I think this is a really cool way to spice up your average steel amp chassis, the purple metal with glossy clear coat really plays with the light and looks really sweet reflecting the warm blue and gold glow of tubes. Next I want to mount a reverb tank overhead on a piece of clear acrylic such that the springs are visible, can anyone advise if mounting a reverb tank upside down (springs up) could affect function?

Thanks and I hope you enjoy!

[Latole]

I tried with a accutronic 4EB3C1B and reverb work same upside down

[thetragichero]

Next I want to mount a reverb tank overhead on a piece of clear acrylic such that the springs are visible, can anyone advise if mounting a reverb tank upside down (springs up) could affect function?

reverb tank mounting plane depends on which tank you have
https://www.amplifiedparts.com/tech-articles/accutronics-products-and-specifications

[nsabatelli]

Ah I did not realize there was a spec for mounting plane, thank you for the lead. My MOD tank calls out horizontal mounting with open side down.

My hope was to mount the tank horizontal with open side up so you can see the springs through the acrylic, do you guys think I would be able to get away with that or is it doomed from the start? Obviously i'm sure they spec the ideal direction for a reason, I'm wondering just how sensitive the tank is to mounting orientation. Any thoughts on this? Thanks!

[sluckey]

Next I want to mount a reverb tank overhead on a piece of clear acrylic such that the springs are visible, can anyone advise if mounting a reverb tank upside down (springs up) could affect function?

The Princeton Reverb use a 4AB3C1B tank that is supposed to be mounted horizontally with open side down. You can mount it with open face up but the springs will be prone to rattle, a condition that only gets worse as the springs age and begin to sag more.

Or, you can get a 4AB3C1A tank that is designed for open face up orientation.

     https://www.tubesandmore.com/search/node/4AB3C1A

I'm assuming that since you want a clear acrylic that you'll also be mounting the tank such that you can see the springs. It can be very boring to watch reverb springs.    But also, you may expose the output transducer to some extra room noises. This transducer and amp circuitry is the most sensitive circuit in the amp, even more sensitive than the input jacks. I suggest you experiment a bit before committing to a permanent installation.

[nsabatelli]

I did indeed hope to see into the tank and I imagined watching crazy spring vibrations through the acrylic. I'm not totally surprised this is not the case.

I do still like the idea of having the springs exposed however, I love design that showcases mechanical systems that are usually hidden. Similar to skeletonized watches where you can see all the inner workings through the case.

On transducer noise, when you say room noises do you mean disturbance from physical sound or RF interference? I wonder if localized shielding might help with the ladder.

I am definitely planning to experiment as I try to attach the reverb tank to the chassis. Thanks for the link to the open face up tank, if my current tank doesn't cut i'll have to try that one next.

[sluckey]

Your chassis is too pretty to hide in a box. If you intend to leave the chassis exposed for tech charm, you may consider mounting the tank like this... Ideally, you would use a 4AB3C1C tank. Accutronics says this is the optimum mounting position for their tanks.

     https://www.tubesandmore.com/products/reverb-tank-accutronics-4ab3c1c-long-decay-2-spring

[nsabatelli]

Oh yes the chassis is the centerpiece, it's gotta stay as exposed as possible. I'm currently leaning towards getting the tank designed for open side up mounting and attempting to mount it roughly as shown.

Does the configuration you show with the open side front reduce the possibility of introducing room noise as you mentioned? I'm not sure I quite understand how reverb tank placement and orientation affects noise in this case. I guess I have some homework to do.

[Gone_Fishing]

You have a beautiful thang there.
I love the PR circuit as a platform and have built a few heads using blackface Bassman chassis’, but none have been a straight PR, I guess because I have an original one.
   I had Heyboer build a DR PT to specs that would fit in the Bassman PT hole, a tapped DR OT, added a PPIV master volume, a mid tone control and a pentode to triode switch. I built another with blackface Bassman transformers, but a picker in Nashville wanted it more than I did. I regretted selling it, so I’m building another clone of that one as I type.
   They are great amps, sound good, dead quiet and take pedals very well.
   Congratulations you have a showpiece there, very nice!