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I've got a Marshall JTM60 and would like to improve the reverb. I know there are different tanks but didn't know what would work or not. I mean I know it'll never be a "fender" reverb but can it be improved. Thanks in advance,Greg.
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Before you find out the hard way - tanks DO sound different, one to the next. I don't mean just by brand or impedance, but unit to unit variation. I used to order a dozen at a time, there would be a couple that sounded fantastic, a couple still pretty good, some run of the mill, and typically a dog tank that I had a hard time selling. And I've never been able to panel-beat the circuitry around a dog tank to make it sound good. So, what can you do & remain sane, more or less? Just try out tanks as you can get your hands on 'em, ones with similar input impedance to the one you already have, so you don't damage the drive circuitry.
I've found short tanks can sound perfectly good so don't be stuck on long tanks only. 3-spring tanks tend to ring out a long time, for that reason I select only 2-spring long tanks. Might not have a choice of short tanks - I usually wind up with a 3 spring. Some tank companies like to claim double the number of springs so you'll see 4 or 6 listed. OK technical point, each spring is made of two springs end to end and welded together in the middle so don't be surprised to see the claim made in the ads or listings. Looks like one long spring to me...
It does make a difference to provide some mechanical isolation, even if it's just covering the open side with cardboard, and putting the whole tank in a "sock," like what you find in the bottom of many reverb amps. Sometimes a little extra padding like packing foam or even bubble wrap, can make a positive difference in making a tank behave with respect to feedback. Yes feedback, the tank and speaker can set up a heckuva "howl" because they're usually located close to each other.This isn't the future I signed up for. -
And really, you haven't told us what improve means to you. What do you not like about it now? What would you like it to do in the future?Education is what you're left with after you have forgotten what you have learned.Comment
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Well to start the volume of the reverb is low and weak. So I can change tanks. What impedences should I be getting? Input and Output should be similar readings? The tank it has now is an accutronic 8DB2C1D medium decay, I think. Thanks to all ,GregComment
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Input and output impedances are not related, any more than microphone impedance is related to speaker impedance.
The reverb has three parts: The drive section, which is more or less just a small power amp to drive the spring unit. The recovery section, which takes the weak output of the spring unit and boosts it up to needed levels, and then the spring unit itself with its connections. Fisrt thing to do is determine which section is the problem, if the drive section is weak, then a new spring unit wil not help.
Rock the amp to shake the reverb springs. Is that a lot louder than reverb on the guitar? Or does that sound constrained too?
Make sure the cables are in the right holes. Pull the cords out of the pan jacks, and touch the tip of each. One will make a hum when touched. THAT one goes into the pan jack marked OUT.
The drive is three sections of op amp in parallel, perhaps try a new IC there, or diddle with the gain by changing resistor values in the feedback.Education is what you're left with after you have forgotten what you have learned.Comment
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Ok so I've got the right rca jacks hooked up. But when I bump the tank its pretty weak even with volume up.Comment
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And touching the tip of that return plug? Is that also weak?
SLap any other reverb pan into the amp and connect ti return cable, is that also weak?
If it is only the one pan weak, then the pan is bad. If any pan works same, then explore the return circuitEducation is what you're left with after you have forgotten what you have learned.Comment
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When I touch the return end there is a hum but its rather weak, less noise than a bad ground on a guitar when you take your fingers off the strings. So like you said the problem is most likely in the return section of the reverb. Anything I'm missing or over-looking?Comment
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Do you have any other reverb amps? If so, pull the return cord from its pan, touch it, and have an instant comparison.
Your return is very weak? OK, have you tried a different set of cords to the pan?
Note there is really one return, but it uses IC3 to select one or the other reverb control. IC3 might be bad, try a jumper from the top of either reverb pot over to C15.Education is what you're left with after you have forgotten what you have learned.Comment
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I don't have a reverb amp to compare to. No change with a different cable either. So I jumper from the case of the reverb pots to C15 ? Before or after C15?Comment
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No no, the top end of the pot, the end farthest from ground, the top end on the drawing. Before C15 I suppose. All I am doing is patching around IC3 to see if it is OK or is the problem.Education is what you're left with after you have forgotten what you have learned.Comment
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We have a winner! Enzo you are the best. I've got a new M5201 on the way. Is there anything special I need to do to install the new chip? Thanks again,GregComment
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Well, yeah. Remove the old one first. Put it in facing the right way.Education is what you're left with after you have forgotten what you have learned.Comment
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Its all good and working as it should. But how can I increase the reverb volume? It seems to lack some oomph, not very "wet" in the mix. Thanks for all the help,GregComment
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