My first amp love is my Marshall JTM 30(1x12). Most Fender sounding Marshall I have every heard and that was kinda what Marshall was going for. I love everything about this amp except for the built-in Reverb. Absolute sucks. My Fender Blues Junior has more Reverb on 1 than this amp has all the way up. It basically keeps the amp from being flat but that's it.
So I was wondering if would be possible to install the same Reverb tank that goes into my Blues Junior into my Marshall JTM30? Is this even possible or worth the headache? My big concern would be disengaging the non-existang reverb and wiring in the new Reverb tank. These reverb tanks going $25 to $45 range on eBay
Would I be better off just buying a Reverb pedal and running it through the effects loop? I also need to find a good replacement handle since the original split.
I replaced the reverb tank in my Marshall DSL50 with the one in my 90s solidstate Laney head, t'was no bother.
Do both tanks have phono connections? If so, you could quickly swap 'em over and see if you get the results you like; you don't even need to screw the replacement into the Marshall, just set it down somewhere.
my marshal (JCM 900) reverb doesnt have the same connections as a fender reverb. Mine only has one RCA-type wire coming out of it (which seems strange to me) where as my fender has an RCA-type input and an output, but I don't know enough about marshal's to say it wont work.
Thanks, Doog. I need to locate the original reverb unit on the Marshall. I have the wiring diagram and the cabinet is deep enough I could easily lay it in without having to bolt it down. I will research and see if I can locate it after work. I hope it's a simple swap so I can control it with the existing reverb knob.
I know just plugging in a reverb pedal is the quickest fix, but I would have to keep it on all the time and it would not be as clean of a solution.
You only have to match resistance (the reverb driver: opamp or tube dictates this) and earthing as far as I know. Other than that you can choose whatever size, delay or number of springs you want. Fender amps (twins, DRs and HR/BDs )are typically long style, 2 springs, and long delay
There's a great guide I'll try and find for you later. You just need a multimeter and a look inside the tank. No need for slogging through a schematic. Tanks are like $25 too. DO IT.
I found this pic of my amp where someone had taken the back panel off (removable) and I think I see the reverb unit at the bottom. Looks like it will be easy to get to. If I can fix this without having to open up the amp itself it will be awesome. I will photograph and test the unit later.
If both tanks have RCA-style connections as Doog said and if you're going for a Fender-style reverb, go for the Twin Reverb tank instead of the wimpy BJr one.
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Replacement Reverb Tank for 4AB3C1B
Used In Fender, Marshall, and Ampeg Amps
Solid, sturdy construction
Long (16-3/4") 2 spring unit , long decay
Input impedance 8 ohms, output impedance 2250 ohms
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I replaced a broken vintage tank in my Vibrosonic Reverb with that one and I can't tell the difference.
Antique Electronic Supply has a great guide (perhaps one George was thinking of) that explains all sorts of reverb-related crap.
If you send them an email, Accutronics can make you a reverb tank to your exact specifications, in terms of length, number of springs, impedance input and output, and orientation. Replacing a reverb is one of the easier things to do in an amp. It's connected with RCA isn't it? That makes it super easy. I'd imagine the tank in there is a short 8DB2C1D, which is decent but not the best, though from that picture, it looks like it's horizontally mounted, so maybe it's something else. I'd go with something like a long 9DB3C1B for surf (or 9DB2C1B for general purpose) and mount it horizontally across the bottom (if you do have 17 inches of room for the tank). If you decide to get one, let me know. I'm thinking about ordering a couple of custom tanks from Accutronics and I'd imagine the international shipping (from Korea) is cheaper per unit when you get more at once.
Keep in mind, though, the tank isn't everything, the reverb circuit also matters.
I came home and tested the reverb again just to be sure. Works but very little depth to it. Just keeps the amp from sounding flat. I took off the removable back plate and found an Accutronics reverb tank inside. Two RCA Plugs. Said it was built in USA.
Accutronics Model no: 8DB2C1D - (good guess there Honey)
Specs based on Serial number
REVERB TYPE 8
INPUT IMPEDANCE-310 Ohm
OUTPUT IMPEDANCE-2575 Ohm
DECAY TIME Medium (1.75 to 3.0 sec)
CONNECTORS Input Insulated / Output Grounded
LOCKING DEVICES-No Lock
MOUNTING PLANE-Vertical Connectors Down
George, do I match the input resistance, output resistantce or both?
You know, that tank is supposed to be mounted vertically, as in the front face of a head cabinet. I've always wondered why Marshall uses those things in combo amps.
You have plenty of room for a 17" tank. You should try to match input and output impedances, otherwise you might not get the best results.
So as long as the number for the reverb tank has *DB**** (DB as the 2nd and 3rd digits) to match my current Input/output impediance I should be okay?
My Marshall JTM 30 has a 8DB2C1B tank.
My Fender Blues Junior has 8EB2C1D Tank.
I was surprised that the only big difference between the two reverb tanks was the input impediance. Does that make a huge difference? These reverbs sound nothing alike. Are there other factors? Does the amp wattage affect the reverb? My Marshall is 30 watts compared to 15 watts that my Blues Junior is.
edit: what is the difference soundwise between 2 and 3 spring reverb tanks? How does the length of the tank affect the sound as well.
Any way to tell if my reverb tank is damaged? Just curious if it might not be working properly which would explain the poor performance. It hasn't been touched since the amp was purchased.
