Uncle Sam's Jamms Amp & Effects Modifications

Blackfacing a Silverface Fender Amp
This modification changes the design of your late 60's or 1970's vintage Silverface Fender Amp to the original "Blackface" amps of the early-to-mid 1960's. Most players agree that the pre-CBS blackface amps sounded much better than the pale-imitation silverface successors designed by the CBS engineers. With this mod, you can take your amp back to the Leo Fender design. In addition, you also restore the bias-setting capability of the amp, replacing the somewhat useless "balance control" of the silverface. These modifications are completely reversible, and no permanent changes to the chassis (such as drilling holes, etc) are required. You'll be pleased with the results!

Volume Sensitivity Mod for Fender Amps
This kit is designed to fix the overly sensitive master volume control in the drive channel AND the volume control of the clean channel for the Hot Rod Deluxe, Hot Rod DeVille, Blues Deluxe and Blues DeVille amplifiers.  All of these models have problems with their volume controls.  If you turn up the volume to "2", you're being blasted out of the room.   It's difficult to find a moderate volume setting - the control is very touchy between "1" and "2".   Turning it above "2" doesn't increase the volume much more.   With this modification, the amp's  volume controls becomes much less sensitive and offers a nice linear increase in volume so that you can easily control the proper volume setting.   

Fender Amp Conversion to EL34 Tubes
Any vintage Fender Amp that uses 6L6 power tubes can be converted to EL34 tubes. A lot of players love the change in tone quality.  EL34's break up a little earlier than 6L6 tubes, giving your Fender a warmer, bluesier sound. This mod is completed in the output section and also in the bias section of the amplifier, and is completely reversible. Can be completed on most models of vintage Fender amps from the 60's and 70's. The modification includes installation of your new EL34 tubes, and proper adjustment of the bias for the new tubes.

Fender Bassman Upgrade for Guitar Players
Over the years, a lot of guitar players have picked up a vintage Fender Bassman amp and used it for guitar. The Bassman was never a really popular bass amp (especially today), so a vintage silverface or blackface Bassman is available at cheap prices. These amps can be made to rock with this modification. Add your own external effects pedals, and you're set to go!

This mod is completed in the driver section of the amp, turning a muddy sounding Bassman into a fine 50 watt guitar amp. Works on vintage 60's and 70's Bassman amps (blackface or silverface).

Also see the Tremolo modification for Bassman amps, below.

Fender Amp Tone Tweaking plus Dual Channel Reverb and Vibrato
Vintage blackface and silverface Fender Amp with two channels (Super Reverb, Twin Reverb, Pro Reverb, etc) were designed with a normal channel and a "vibrato" channel. The reverb and vibrato only worked in the vibrato channel by design. But you can tweak the tone quality on the normal channel and also add reverb and vibrato to the normal channel as well (your existing reverb and vibrato controls will control the reverb for the normal channel - no extra controls or drilling of the chassis is required). The result is an amplifier with the original sound on the vibrato channel, but a distinctly different tone characteristic in the normal channel, along with the option for reverb and/or vibrato. Add an external A/B box for switching, and you have increased the versatility of your Fender.

Fender Blues Jr. Revamp  The Blues Junior is a great little amp, but we have a mod that will make this amp really shine.   After the mod, the amp boasts clean, sparkling top end, a huge sweep of mids and rich bass response.  The smooth, slightly compressed tube breakup stays articulate thanks to improved power filtering and upgraded tone caps. We also improve the reverb, replace the input jack, and change the bias network to allow the amp to run cooler without sacrificing tone.

Fender Bassman Tremolo for Guitar Players
Over the years, a lot of guitar players have picked up a vintage Fender Bassman amp and used it for guitar. The Bassman was never a really popular bass amp (especially today), so a vintage silverface or blackface Bassman is available at cheap prices.
This mod takes part of the circuitry in the "Bass" channel and modifies it to be a tremolo circuit for the normal channel.   Very popular with jazz players.  You now have the Fender sound with tremolo, in a convenient head.  Hook it up with the cabinet of your choice, and mellow out!

Fender Tone Stack Modification
This is for players who continue to look for that elusive tone, and want just a little more "oomph" from the tone controls in their vintage Fender amp.    Can be applied to most Fenders from the 60's and 70's - both those amps with the 'mid' control, and those without.   Your Fender will be spiced up with new tonal variance, and your ears are going to dig it!   For dual channel Fenders (such as the Twin, Super, etc), you can mod just one of the two channels and leave the other one as the original Fender tone.

Fender Custom Vibrolux Reverb Modifications
The blackface Fender Vibrolux Reverb is one of the sweetest sounding amps Fender ever created.   But when they went to build a reissue of this fine amplifier, most every guitar player will tell you they really missed the mark.   The Custom Vibrolux Reverbs are raw sounding, hissy, and too loud with little breakup.   This mod will tame down the beast by installing the missing negative feedback loop (what were they thinking?!?), lower the hiss by cutting back on the extreme gain in the front end, and sweeten up the tone by modifying the tone stack.

Marshall Amp Conversions between EL34 Tubes and 5881/6L6/6550 Tubes
Marshall made many of their earlier model amps in two versions - one with EL34 outputs, and the other with either 5881, 6L6 or 6550 output tubes. The difference in sound can be distinctive, and of course is personal preference. But what if you would like to change your amp from EL34's to 6L6 outputs (or vice-versa)? The bias circuit must be modified, and our technical service department can take care of that for you.  The modification is completely reversible.

Marshall JCM900 Tone and Equalization Improvement
No doubt, the JCM900 series of Marshall amps are well-liked, well-built units from the 1990's. But everyone's taste in tone quality is a little different, and a lot of players say that the JCM900 could use a little less treble, and a bit of a boost in bass and mid-range - especially the bass. This modification gets rid of that ear-piercing "ice pick" treble and brightness, along with smoothing the grittiness of the distortion -- making the amp sound more full and punchy. We don't know of anyone who has had this mod installed that wasn't pleased with the results.

Adding adjustable bias to the Peavey EVH5150 amp
The purpose of this modification is very simple - it changes the fixed bias design of the Peavey EVH-5150 to the much-preferred adjustable bias. A lot of players love their 5150, but the bias is permanently set on the "cold" side. There is a lot more tone just waiting to get out of your 5150, and it's available to you with this mod. Peavey later corrected this fault in their series II version of the 5150 - if your unit has red and black meter probe jacks on the left-hand side of the back panel of the amplifier, you already have adjustable bias and do not need this mod.

Crybaby modifications
Looking for more from your Dunlop Crybaby?  We have a number of mods that can improve the tonal range, add more "voice" to the wah, or add true bypass so that the pedal isn't draining your signal when it's not being used.   We can install the legendary "Fasel" inductor in place of the stock inductor.   

Pedal modifications
The most common pedal modification is "True Bypass" for those pedals which don't feature it.   Many pedals leave the pedal circuitry connected when the pedal is in the bypass mode.   This slightly degrades your "bypass" signal.  It's not such a big deal if you have just one or two pedals, but if you're working a pedal board with a dozen effects, you'll have some significant deterioration to your straight signal when most or all of your pedals are bypassed.  This mod can fix each of your pedals to feature "True Bypass", eliminating the signal drain.   Price varies with the pedal.

Output power select switches
You love the sound of your amp - the way it breaks up as you crank the volume is phenomenal.    You just wish it would sound the same at a lower volume.   An amplifier output power select switch may be what you're looking for.   For example, decrease a 100 watt Marshall down to a 50 watter for smaller venues, and still get that great tone.   Price varies with the amplifier - not all amps can be modified.

Master Volume Control.  If your tube amp doesn't have a master volume, in most cases we can add a Post Phase Inverter Master Volume control (called PPIMV by techs).   This master volume control allows all of the wonderful tonality and crunch added in the phase inverter to be still part of your signal, with the volume adjustable to the level you desire.  This is the next best thing to the Hot Plate and other attenuators which sound great, but tend to damage your amp.  Much better than stock master volume designs on most amps. 

Amp standby switch installation.  We're not sure exactly why, but some tube amps simply don't have a standby switch, and that's not good.   A good example is the otherwise very fine Peavey Delta Blues - why didn't they include a standby switch?  But not to worry - we can add one, and without drilling a hole through the chassis.  We modify the circuit and install a 3-position switch in place of the on-off switch, giving you Off/Standby/On all in one toggle switch.  

FX Loop Mods.    Some of the amplifier manufacturers do a great job of designing their effects loops, while others - well ... not so much.   The Mesa Boogie Dual Rectifier and Triple Rectifiers are cases in point.   These otherwise awesome rock and metal heads have terrible-sounding parallel FX loops.   We can convert the loop to a series loop, complete with normalled switching so that a patch cord is NOT needed if you are not using the effects loop.   Also, the foot switch is modded so that it will continue to switch the loop in/out.    Mods to other amps' loops also available. 

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