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How can I tell if Reverb is working?


Josh D
Posted on Tuesday, December 14, 2004 - 03:32 pm:   

Ok, I'm beginning to think that the HD150R I bought doesn't have working reverb. Just a novice here, but when clicking on the foot pedal, I can't tell a difference in the tone, regardless of where the reverb dial is set to. Phaser on the other hand does produce an audible change. Is there something special I need to do to get reverb working?
Steve Kennedy (admin)
Posted on Tuesday, December 14, 2004 - 05:30 pm:   

If you have a shorted footswitch cable or switch, the Reverb may appear to be permanently turned off. Try disconnecting the switch wires where they connect to the bottom of the amp chassis and see if your Reverb starts working (the switch is only needed to turn it off).

You could also try reversing the footswitch leads and see if the phasor disappears and the reverb shows up. If so, you need to find the problem with your footswitch system.

If reversing (or disconnecting) the wires doesn't really change anything, then see if the Reverb tank (spring) is plugged in. If it is disconnected you won't hear it or if it is plugged in backwards you could have a hard time detecting it.

If this checks out and reversing the reverb connectors doesn't change anything, then you either have a dead reverb tank (it happens after a few decades!) or there is a problem in the reverb circuitry inside the amp.


(Message edited by admin on December 14, 2004)
Josh D
Posted on Tuesday, December 14, 2004 - 05:58 pm:   

Steve: thanks for the helpful post. I'll definately try reversing the pedals and take a look at those wires. Are reverb tanks something that can be found easily through aftermarket channels?

Also, when phaser is enabled there is a wowwww..(light static)...wowwwww...(static)....woowwwww w
sound that comes through the speakers. The louder the volume, the more audible that sound is. Is this normal.

And one other thing. There is always audible static, buzz, or fuzz. Not sure which fits best, but is that normal. It's not overpowering, but you can tell it's there.
Josh D
Posted on Wednesday, December 15, 2004 - 09:57 pm:   

Ok, disconnected the plugs inside the amp on the ceiling and still no dice. Where can I find the reverb tank spring? Not really even sure what the reverb tank looks like.
michael kaus
Posted on Thursday, December 16, 2004 - 04:48 am:   

It's down in the bottom of the amp in that bag or taped to a piece of cardboard. Bump the amp with the reverb on- do you hear a crash with reverb? If not, it's not working at al and will probably require a trip to the vet. By the way, you were supposed to disconnect the cable that plug in to the chassis from the foot switch. Is that waht you did or did you disconnect the ones under the chassis? Mike.
Posted on Saturday, December 25, 2004 - 10:38 am:   

This guy on EBay "reverbtankcom" sells 3 spring reverb tanks for the MM amp ...I think the ones he sells are 17 inches long... he says they sound better than the original as well ...haha...anyway... they are around $45 bucks using 'buy it now' or $39 for the long ride...he also told me he can custom make reverb tanks for the same buy it now price... Remember that all reverb tanks are not created equaly, you have impedence to factor in....Jim
Doug Elick
Posted on Wednesday, January 05, 2005 - 07:08 pm:   

I wouldn't waste my money buying a reverb tank on Ebay. The brand of manufacture is "Accutronic"; a cursory search on Google popped up this site "http://www.stf-electronics.com/Page0014. Html", which claimed to have a wide selection of them, none over $30. Just scroll down about half way (or research further w/Google).

There should be a model number stamped somewhere on the tank, but should there not be, just ask around for someone who has a similar model amp to yours.

As mentioned before, the reverb tank is a metal box inside the "pleather" bag in the bottom of your amp case. There should be two cables with RCA plugs running up to the underside of the amp chassis (and to corrosponding RCA outlets).

The tank is essentially a set of springs suspended between a pair of transducer coils, one to put the signal onto the springs and another to pick 'em up.

Before you purchase a new tank, you may want to try a few simple (safe) tests. Unplug the tank (remember which plug went where; it'll save you the hastle of figuring it out later) and remove the screws that hold the bag to the bottom of your case. Slide the tank out and remove the cardboard taped to the bottom of it. You'll see the springs suspended between what looks like two very small transformers. Each one of these transformers (pickup coils, really) have a set of leads soldered to the RCA jacks. In my case, one of those leads had broken loose; 5 minutes with a soldering iron brought it back to life.

Even if the leads look ok, jiggle them a bit and then test their continuity with a multimeter; you should see (about) between 1500 and 2500 Ohms on each coil. Beware however, that 25 years of corrosion has built up an may effect your readings/performance, which brings me to my second point. Even after I repaired my reverb tank, I still had problems with it cutting in and out. Over two decades of oxidation had caused the circuit to break.

Find a spraycan or applicator pen of a product called "DeOxit" (Radio Shack sells it). I can't stress how well this product works (sooo much better than anything else I've found); a quick squirt on the RCA plugs and jacks completely disolves the oxidation and brings them back to the day they were made condition. DeOxit is somewhat expensive ($14 for a can of it and a can of contact preserver to prevent future problems), but it seems to last a long time and works VERY well. Since I have my amp open right now, I sprayed all the input jacks and tube sockets and all the little crackles and pops I used to hear when touching the tubes or unplugging cables have completely vanished.

Sorry for the endorsement, I don't own any stock in the company, but the stuff seems to work so darned well!

If you've checked the physical and electrical properties of the reverb tank and still get a big fat "0" on your meter, then it's time to think about replacing things.

Posted on Wednesday, January 05, 2005 - 07:54 pm:   

buy a EH holy grail reverb pedal
they sound better and there is no slappy spring sound
Posted on Saturday, February 25, 2006 - 11:37 pm:   

Doug Elick, thanks for the great post. My 210-HD has had no reverb for, oh I don't know, 20 years?! (I bought it new in 1970-something) Until I read your post I had NEVER looked inside the reverb tank. What did I find this morning? The two tiny wires on one side are disconnected just as you described. Anyway, the leads are extremely tiny, and the position of the breaks give me no room to solder. For $31, including shipping, I just orderded a new tank from Mojos...what the heck, eh?
Doug M.
Posted on Monday, February 27, 2006 - 11:21 am:   

I just replaced the reverb tank in my 112RP-100 with one I purchased from Mojo. I had a good experience doing business with them.