Mesa 20/20 Deep Mod
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Tripoutski
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My version of the deep mod is pretty clean and readily accessible with no drilling.
I feel a bit bad because I did this mod over a year ago with help from this site, but I never came back to post about it. I think that some of you may like the push-pull knob idea.
I replaced the standard volume pots with push-pull switchable pots of the same value (Mouser has these). Then I ran some wiring through the existing wiring harnesses of the amp inside back to the circuit board in question. Then, much like the others here, I de-soldered just one side of the circuits, soldered to the board and the circuits, and used a little shrink-wrap to clean it up. It is very clean inside and it turned out great for me. Thanks to you all for your suggestions!
I wanted to use the outer presence knobs for the switchable pots, but the transformers would not allow for the longer pots inside. No big deal, I used the middle volume pots instead where there was plenty of room:
The knobs in their normal "off" position:
The knobs pulled engaging the Deep Mod:
Rock on!
-Trip
I feel a bit bad because I did this mod over a year ago with help from this site, but I never came back to post about it. I think that some of you may like the push-pull knob idea.
I replaced the standard volume pots with push-pull switchable pots of the same value (Mouser has these). Then I ran some wiring through the existing wiring harnesses of the amp inside back to the circuit board in question. Then, much like the others here, I de-soldered just one side of the circuits, soldered to the board and the circuits, and used a little shrink-wrap to clean it up. It is very clean inside and it turned out great for me. Thanks to you all for your suggestions!
I wanted to use the outer presence knobs for the switchable pots, but the transformers would not allow for the longer pots inside. No big deal, I used the middle volume pots instead where there was plenty of room:
The knobs in their normal "off" position:
The knobs pulled engaging the Deep Mod:
Rock on!
-Trip
RectoStudioGuy
Well-known member
The push/pull is indeed a great idea....On the other hand knowing the GIANT mid-range hump of the 20/20, would you ever use it without the deep mod?
The push/pull is great, keeping the amp cosmetically intact.
I think I will go with the P/P mod for mine.
I have two 20/20 amps, one silver face and the other black front plate.
The black face from ebay came with the deep mod that previous owner did.
the caps are desolderd at only one side and left open. It would be a easy mod job for the Push/pull.
I and many of my friends keep going back for the silver face for solo works. I find that mids hump helps cut through a mix better somtimes than modded sound. I guess it all depends on one's preference.
For a sound engineer, a tone is a tone and a sound is a sound.
finding a right sound for a right spot, how , when, where probably counts more.
As they say, this tone buiness has become like fashion buiness. trendy like vogue.
Who knows, the mid hump may come back a decade or two later.
Thanks everybody here for the valuable info.
I think I will go with the P/P mod for mine.
I have two 20/20 amps, one silver face and the other black front plate.
The black face from ebay came with the deep mod that previous owner did.
the caps are desolderd at only one side and left open. It would be a easy mod job for the Push/pull.
I and many of my friends keep going back for the silver face for solo works. I find that mids hump helps cut through a mix better somtimes than modded sound. I guess it all depends on one's preference.
For a sound engineer, a tone is a tone and a sound is a sound.
finding a right sound for a right spot, how , when, where probably counts more.
As they say, this tone buiness has become like fashion buiness. trendy like vogue.
Who knows, the mid hump may come back a decade or two later.
Thanks everybody here for the valuable info.
Tripoutski
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I found the part number for the push-pull pots from Mouser. Here is the pot. As I remember (4 years ago) I did not have to do any shaft modifications to the pots as well. I think that they dropped right in.
-Trip
edit: spelling... again...
-Trip
edit: spelling... again...
I'm a 1st time poster and am going to attempt to make the deep mood to my 20/20. Thanks to Tripoutski for the link to Mouser (got the pots) and for the pics...I feel comfortable tackling this. Just wondering if someone could describe the wiring process for the switches...anything I need to be careful of etcetera...a schematic or diagram would be appreciated...I can follow the pics to get into the general area but am not too familiar with how switches are typically wired...
Tripoutski
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erakare said:
Cool! Take pics if you can so we can all see how it worked out. Everyone benefits from as many pics as we can provide.
erakare said:
I have no schematic, but it really is not hard at all. Simply run a pair of wires for each channel. As you can see from a few different pics you run one end to the circuit board and the other to the one end of the component that you de-soldered. On the switch end, just run the pair to two leads that will close the circuit when pushed, open it when pulled. The pic that I posted of the inside front panel show these very clearly. My pic shows the black and yellow on the left pot switch and the black and red on the right pot switch. Since the switches are actually DPDT, you could actually switch both channels of the deep mod with one switch, but I liked having the flexibility of switching each channel individually.
Keep us posted!
Thanks for the reply! Seems simple enough...so the exiting wires connected to the original pots controlling the L and R volume (white, purple and black) will connect to the front of the new pots (the end attached to the rear of the front face of the amp) as seen in your photos, and the two wires from the circuit board (whatever colors I choose) will attach to the left side (looking from above in your photo) of the new DPDT switches...I assume that the poles I am unable to see in the photo to which the existing white/purple/black wires are attached are wired similarly on the old and new switches, so I can simply match those 3 wires to the consecutive poles based on how they're currently attached...
Whew..Jan-Mikael
Whew..Jan-Mikael
Tripoutski
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Exactly! The wires that you cannot see the connections to do go to the pot itself and will connect to the same corresponding terminals as the old pots. Only the top left of each switch are new wires. It is just as you described in your post. I don't think that you will have a problem with this as you have it down already!
Well...easy enough but still troubling due to my clumsy soldering skills, cheap soldering iron and general ham-fistedness...got it done but I think I must have wired the switches backwards because when I have them pulled out it sounds normal and when I have the pots pushed in it sounds bassier/richer...not a big deal...I actually like having it that way now that I've played with it for a few days...
Not sure I want to post pictures though as it really isn't pretty...maybe I'll wait a while and go back in and re-do it and use thinner gauge wire...that might have been part of the issue with why it was difficult to solder...
Not sure I want to post pictures though as it really isn't pretty...maybe I'll wait a while and go back in and re-do it and use thinner gauge wire...that might have been part of the issue with why it was difficult to solder...
RectoStudioGuy
Well-known member
And might I sugguest a decent varible temp soldering station. Really helps.erakare said:
NightRider
Active member
I have a 20/20 coming to me... the guy says one channel is modded the other isn't.... anyone here run it likes this or should I just go and mod the other channel??? Thanks
RectoStudioGuy
Well-known member
If you're intending to use it stereo I'd personally want both to be modded
I'm new to this forum, as I recently acquired a 20/20. The first thing I was sure I wanted to do - even before receiving my 20/20 - was to perform the "Deep Mod" on this unit. Everything I had read up on ahead of time lead me to this line of thinking. And after reading the 4 pages of posts in this thread, and seeing the many different ways that other members have performed this mod (fixed, switchable with a single toggle switch for both channels, a toggle switch for each channel, push/pull pots), I decided to go with the push/pull pot configuration, with a push/pull switch for each channel - this configuration was the most appealing to me both ergonomically and functionally.
A couple of interesting notes here. I contacted Mesa to see if they had a compatible push/pull pot that they use in another Mesa amp. Well, it turns out they DO have a new part that fits the bill
! It's 100K-ohm, linear taper pot with a switch and a push/pull shaft. For all those interested, the part# is 596151 ($8.90 ea.). The parts department may still not recognize this as a valid part number. If this is the case, have them call a tech while they keep you on hold, as this part number was not yet updated in their parts system as of last week. The shaft is the same length as the original 20/20 volume pot, it just doesn't have the flat edge - the shaft is completely round. Since it's a push/pull, I did not put the little teflon spacers back on the pot shafts before attaching the knobs, as I'm sure they'd get jammed due to the shaft exposing a notch when it is in the "pull" position, and the spacers would fall into the notch preventing the shaft from being pushed back in again.
While I was at it I also ordered 4 chrome knobs to replace the black ones (part# 409110, $4.90 ea.). However, 2 of the 4 knobs appear to be defective - I cannot tighten the allen screws nearly enough before the screw stops turning; as if the threads were not tapped properly (and no, it's not a problem with the allen screws). They might have a QA problem with these - have them test the screw travel completely before sending them to you.
I'm pretty good with a soldering iron and wiring, so the actual wiring was no problem - I did take my time though and made it look good.
OK - so now the big test . . . how does it sound??? First off, let me say that I don't play at very loud volumes at all - whether I'm at rehearsal, at home practicing, or even at gigs at mostly small clubs. So perhaps my opinion will change at higher volume . . . but to me, the 20/20 sounds MUCH better WITHOUT the Deep Mod :? ! The volume gets noticeably lower when I pull the pot to activate the mod - it's not drastically lower, but it is definitely noticeable (maybe 10%-12% lower). The other undesirable characteristic - and the main issue I have with this mod, is that it seems to kill the upper mids. Anyone else feel the same way about this? I REALLY like the unmodded sound much better!
The push/pull pots make it completely seemless, so I have no regrets in performing the mod . . . but again, I'm very curious to hear if anyone else has had the same or similar results with the deep mod.
A couple of interesting notes here. I contacted Mesa to see if they had a compatible push/pull pot that they use in another Mesa amp. Well, it turns out they DO have a new part that fits the bill
! It's 100K-ohm, linear taper pot with a switch and a push/pull shaft. For all those interested, the part# is 596151 ($8.90 ea.). The parts department may still not recognize this as a valid part number. If this is the case, have them call a tech while they keep you on hold, as this part number was not yet updated in their parts system as of last week. The shaft is the same length as the original 20/20 volume pot, it just doesn't have the flat edge - the shaft is completely round. Since it's a push/pull, I did not put the little teflon spacers back on the pot shafts before attaching the knobs, as I'm sure they'd get jammed due to the shaft exposing a notch when it is in the "pull" position, and the spacers would fall into the notch preventing the shaft from being pushed back in again.While I was at it I also ordered 4 chrome knobs to replace the black ones (part# 409110, $4.90 ea.). However, 2 of the 4 knobs appear to be defective - I cannot tighten the allen screws nearly enough before the screw stops turning; as if the threads were not tapped properly (and no, it's not a problem with the allen screws). They might have a QA problem with these - have them test the screw travel completely before sending them to you.
I'm pretty good with a soldering iron and wiring, so the actual wiring was no problem - I did take my time though and made it look good.
OK - so now the big test . . . how does it sound??? First off, let me say that I don't play at very loud volumes at all - whether I'm at rehearsal, at home practicing, or even at gigs at mostly small clubs. So perhaps my opinion will change at higher volume . . . but to me, the 20/20 sounds MUCH better WITHOUT the Deep Mod :? ! The volume gets noticeably lower when I pull the pot to activate the mod - it's not drastically lower, but it is definitely noticeable (maybe 10%-12% lower). The other undesirable characteristic - and the main issue I have with this mod, is that it seems to kill the upper mids. Anyone else feel the same way about this? I REALLY like the unmodded sound much better!
The push/pull pots make it completely seemless, so I have no regrets in performing the mod . . . but again, I'm very curious to hear if anyone else has had the same or similar results with the deep mod.
RectoStudioGuy
Well-known member
I did not notice it killing my upper mids but merely bringing up the low end to the level of the mids. Could perhaps the route you chose for your wiring coming from the back to the front and then back again be the issue? Wire routes have been an issue with amps since day one. Take an original Plexi, for example, everyone of them sounded different...due to the slightest difference in the point-to-point wiring that was employed. Just something to think about.
I'd say your experience is close to mine. You do lose a significant amount of overhead and perceived volume because the tone is not as cutting without that mid-bump. I'm pretty sure this cut is what gives the little guy its rep as such a loud amp. At low volume, I also prefer the cut of the non-modded setting. I wired mine to be switchable but I only ever switch one side (which feeds an EVM 12L) to the deep mod and I leave the other channel (which feeds a Celestion 12) with the mid-hump. The two make for a nice balance and then I can just mix to taste between the two.
Wayne
I decided to make sure it wasn't my ears playing tricks on me. So this morning I made sure I powered on the 20/20 with the deep mod enabled, and used ONLY the deep mod for a while. WOW! :shock: What a difference a night's rest on the ears makes - either that, or I've got some other inconsistency in my rig ... because NOW it sounds GREAT with the deep mod enabled, and now switching back and forth between stock and "deep mod" I prefer the deep mod. Hmmm - oh well ... sorry for the false alarm !
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