Hi all! First of all, so glad to find that this community exists. You'll have to forgive me in advance for any lack of technical knowledge here - amp repair and modification remains an enchanting mystery to me.
Background: Inherited a real junked 110 RD-50 about 8 years ago. Was totally useless (someone had tried to replace the speaker and totally destroyed the amp in the process), but about a year ago I took it out of storage in California and had someone (at the incredible Atomic Music in Maryland) bring it back to life.
All in all, I'm extremely happy with the amp, but was hoping to replace the reverb tank with something that will give it the big/wide/long sound of a classic Fender Princeton Reverb. Right now (I think?) the reverb tank works fine, but even cranked up to 10 the reverb feels pretty "short." That said, maybe mine just doesn't work as it should and I just haven't played with enough MM's to notice!
Do any of you have suggestions for a replacement tank that will give me that "bigger" reverb?
Thanks in advance for any thoughts or advice. Look forward to bothering you with more questions about my favorite little amp!
Stock and Longer Delay Tanks
The stock reverb tank for the RD50 is model 8BB2A1B. I believe Accutronics was the original brand, but there are other brands today to choose from. The tank is described as a short tank with medium delay.
Here's is how I would approach it.
First, check that your tank is connected properly. You can swap the RCA plugs under the chassis to test. The reverb should get noticeably better (if originally wired backwards) or noticeably worse.
Second, check that your reverb cables are ok. Swap them out with a know good pair of cables.
If no improvement, your tank may be worn out.
If you want a stronger/deeper reverb, try replacing the tank with a new version of the original spec tank.
If you want a longer decay time (reverb takes longer to trail off), try a model 8BB3D1B long delay tank.
I personally find the original spec MOD 8BB2A1B sold by amplifiedparts on eBay to be just about perfect.
SO appreciate this thorough response. Will go home and give the tank a checkup, per your instructions.
My *hunch* is that it might be worn out (when I had the amp "brought back from the dead" they replaced a lot, but know they left the reverb alone), and, if so, the info on the replacement tanks is extremely helpful.
Thanks again! Will definitely be frequenting this message board from here on out.
Glad to Help
The RD50 is my favorite MM amp, I've brought more than a few back from the dead...
What speaker are you running in yours? Have a Celestion Gold G-10 in mine currently, trying to find a 10" that sounds as good as the 12" WGS Reaper HP sounds in the 112 model.
Going to try the 8BB3D1B
When I had the amp "Lazarused" I told them to do it for as cheap as possible, figuring that once I could make sure it was still functional I could upgrade. Following those instructions, the guy who fixed it put in an Eminence Legend. Doesn't sound bad, but I'd actually been looking at replacing it with the Celestion G-10 to give it that extra love. Are you happy with it?
After fiddling with the reverb tank it appears that everything was plugged in properly, so might just be that the tank is tired? Still sounds good (just a little shorter than I'd like), but just purchased the 8BB3D1B to try it out. For $20 it's worth a shot. Will let you know what I think when it arrives!
Reverb Tanks and Speakers
For $20 it's worth experimenting with different Reverb tanks, let us know how it works out.
As for speakers, the Celestion Gold G-10 is a great speaker. Is there something "better" for an RD50? Could be, but I haven't found it yet and have tried quite a few speakers.
The 12" WGS Reaper HP (their higher power version of a Celestion G12H30 Anniversary Edition) to my ears, is just about perfect for the 112 RD 50. My friend has a '66 Vibrolux Reverb, and he can get his RD 50 with the Reaper HP to sound virtually identical. In fact, the MM is now his go-to jam and gig amp. If WGS (or anyone) made a 10" version of this speaker I'd think it would be a great match for the 110 RD50.
Sticking With The Original / Cardboard?
So the new MOD 8BB3D1B long decay tank that I ordered finally came in yesterday.
Put in the new tank, fired her up and...I don't know, it just wasn't doing it for me! Though I liked the long decay it gave the reverb, it no longer had the spring-y punch that I'd gotten used to. Didn't have the presence/attack/what have you that the original tank did. The new MOD didn't feel particularly strong or deep, just long.
So...reinstalled the original. ¯\_(ツ)_/¯
As I got to work installing it (which, as a total amplifier ignoramus, was BIG stuff for me, haha) I noticed that inside of the insulation bag, the original tank had been taped to a small piece of cardboard on the bottom side. Now, since I'm a total novice here, I was curious about the cardboard. Is that pretty common? I can understand wanting something to stabilize it if you didn't have the insulation bag, but are both together a recommended combo? Also, unlike the original Accutronics tank, the new MOD one had rubber pads, seemingly implying that it can or should be installed without the bag/cardboard.
I didn't have a ton of time to play with all the different combinations (just bag / cardboard + bag / just tank / tank + cardboard / etc) so will probably pick that up on a lazy Sunday, but any thoughts from the community here on what preferences they have when it comes to tanks in MM Amps?
I have used both methods.
I have used both methods. Seems better to me to have the tank in a bag, for no other reason than to keep it clean.
(Leo used cardboard screwed to 2 pieces of wood in his Fender amps, seems wrapping some tape around works just as well!)
Bag + Cardboard?
I agree...seems to "protect" it, if only superficially.
Do you use cardboard too, or just have the tank in the bag on its own?
All the original tanks I've seen...
...had the cardboard taped onto the bottom (open side) of the tank. Presumably to give the internals some protection.
The MOD tanks I've installed inside the bag as is.
Kinda surprised the new MOD tank doesn't sound as strong as your original, it should be the same or stronger. Did you try connecting the cables both ways? As I mentioned previously, I just didn't care for the longer decay, otherwise a good sounding reverb to my ears.
Will Try Again
Will definitely give it another shot once I have some time on my hands. Definitely think it was worth the $20 to learn a little more about reverb tanks and to appreciate what I had!
I retaped the cardboard onto the new MOD tank when I put it in the bag. Not sure if the cardboard has any effect on the sound or if it's just for protection, but as previously mentioned, curious about trying out different combinations.
I liked the sound of the long decay, just didn't feel like it had any attack or punch to it. Will definitely try again, but my thinking is that I should be grateful for the crisp, wet, classic spring sound that I already had and just use a pedal for when I want a more "dramatic" reverb. Think the medium decay of my original tank is more suited for "everyday" use.
Again though, glad to have tried it out and am glad to have an "alternate" if the day ever comes where I want it! Thanks so much for your initial help on this, inertian. Was a great inaugural experience with this community. Certainly won't be the last!
When I replaced the tank in
When I replaced the tank in my RD100, I cut a piece of double thick cardboard, (and since the old one was taped), I also used masking tape to affix the cardboard. Nestled inside a bag, where the dust bunnies can't climb in.
(I could tell no difference in the past whether the tank was attached through the grommets, or the bag, but I have always used cardboard under the tank).
Cardboard It Is!
Appreciate the input, Bill. Learn something new on these boards everyday!
Will trust my cardboard + bag combo for now.
So, I put a MOX 8BB2A1B [ Mox are for sale on ebay EU and are great tanks!] The tank really solved my reverb hum issue and sounds great. But, the decay is like 4 seconds long! It's a medium decay  three spring tank but sounds very long, about twice as long as the original. Any body know if its possible to shorten the decay on a tank or even to remove one of the 3 springs? Or if they make a short decay version of the small 2 or 3 spring tanks in this impedance? I would put the original back in but it hums pretty bad even if I re-orient it's location for minimal transformer interference.