JC 120 Reverb

[whojamfan]

Hello,
New guy here hoping to get some help. I have an old Roland JC 120 and I want to replace the reverb tank. I am hoping I can just get a nice long accutronics and screw it into the bottom and plug it in the way the existing one is.

If not, is there a direct replacement that will improve the sound of the reverb in this amp?

The chorus and vibrato are so awesome, it is a shame that the reverb is so shallow(IMHO).

Also, there is a little trimpot on the back panel to the left of the 1/4" jacks(this one has no effects loop) and cannot find out what it does and do not want to touch it untill I do.

I appreciate any help I can get on this. I have not owned the amp long, and just want to make the reverb nice and lush.

[chipaudette]

Hi,

I've had trouble with the reverb on my JC-77. I'm always breaking something inside the reverb tank. I've replaced the tank once and repaired the tank twice. I, too, have been thinking about replacing the tank with an longer-decay Accutronics reverb.

To buy a replacement Accutronics tank you need to specify the desired input impedance. I don't know what the JC circuit expect from the reverb tank. So, to help both of us, I just emailed Roland and asked for a schematic and for the input impedance of the reverb tank. We'll see what they come up with.

Does anyone else know the input impedance of the Roland reverb tanks?

Chip

[chipaudette]

Oh, and I've also got an email in to Accutronics to see if they can suggest a couple models for my JC-77. I'll let you know what they say.

Chip

[chipaudette]

I got a very quick reply from Accutronics...

>>>> Begin Quote

Chip,
I have a note that shows a Roland JC-77 comes with a Hokusei #58 which can be replaced with an Accutronics model 1AB2D1A. This can be upgraded to an Accutronics model 8AB2D1A. If you are looking into replacing the original unit with a long 2 spring unit then you would want to use a 4AB2D1A or a longer delay 4AB3D1A. If you want a fuller, thicker boomier sounding reverb, a little more bassy than a type 4 then you might want to try a 9AB2D1A 3 spring unit.
Regards,
Cal Shuett - Accutronics Reverb
A Division of SEPI-GROUP

>>>> End Quote

That's some good info. I'm gonna dig in a bit tonight to see what works for me. I hope that this helps with your JC-120 question.

Chip

[whojamfan]

Thanx for the response, did Accutronics say anything about this being a plug and play deal, or are amp mods necessary?

[chipaudette]

Since they said "replaced with an Accutronics model 1AB2D1A", I assume that no mods are necessary. And, since he suggested the other models, I assume that their input/output impedances are all the same (which are, I believe, the only relevant parameters). By browsing their site, I'm sure you (and I) can confirm this to make sure.

If the tank has the right input/out impedances, I don't believe that I'll have to modify the electronics within the amp. Therefore, I believe that I'll only have to make physical mods to my amp...and only if I go with the longer reverb tanks.

The stock JC-77 has a short tank squeezed into a tight space, so there's no room there for a longer tank. Therefore, I'll have to move the tank to the bottom of the amp cabinet, put it in a bag Fender-style and screw it down, and then make longer cables to reach the tank when on the bottom. I don't know about the JC-120, though. You'll have to look in the back of your amp to see what will fit.

If you're concerned about mods to the electronics, I'd suggest emailing accutronics. The guy responded super-fast. I went to their website and used the email address: info@accutronicsreverb.com.

Let me know what you find out.

Chip

[whojamfan]

I just emailed them and hopefully we can both get what we want. My 120 has that little tank as well, and I just don't get it.

It seems to me that this JC line of amps was made to compete with Fender Twins when it came out, and you would think that the reverb would be just as cool as the stereo chorus/vibrato effect the amp is so respected for.

Years ago I had a 70s chorus/echo unit from Roland that had tape delay, chorus, and some of the nicest spring reverb I have ever heard. It was a giant rack unit that weighed a ton and the tape delay kept going out, so I dumped it cheap.

If only they had used that reverb in these amps.....

Thanx again, and keep me posted on what you find out and I will do the same.

[chipaudette]

For ease of installation, I'm thinking about sticking with the short tank but going to the 3-spring version (8AB2D1A). The old one was a 2-spring guy and it was quite tinny. I'm hoping that the 3-spring would cure that.

So, while I value a decent sounding reverb, I don't know if the long-spring version is what I want with this amp. The JC-77 isn't for the surf-thing. I've got my Fender for the long-spring sound.

If you do go long-spring for your JC-120, let me know how it works out.

Chip

[whojamfan]

No reply from accutronics yet. Hopefully, this can be a simple operation.

Anybody know what that trimpot on the back panel next to the jacks does?

[whojamfan]

Still no word from accutronics. What a bummer.

[chipaudette]

Really? I got mine within 6 hours.

I'd try them again...but don't be a jerk about it...just assume that you got caught in a spam filter or something. I can't believe that they'd be purposely ignoring you when I got service so fast.

Chip

[drasp]

Anybody know what that trimpot on the back panel next to the jacks does?

+1 - Just got my JC-120 and no clue what this does. Anyone?

[antiunderscores]

I have a type 8 in my crate, it gets an alright reverb but a long type 9 would probably be better, and i've considered it a couple of times.
The way i think of the different type is:
The type one is your basic, small "reverb for the sake of it" although some may like this sound, thats cool, different tastes. type 4 is what a lot of fenders were equipped with for that surfy sound. A type 9 is for that deep, huge sound. and type 8 is the deep sound scrunched into a small box. The first number represents the type. Heres a great page on what the numbers mean and some example amps they are in, etc:
http://members.tripod.com/~roymal/accutron.htm