For quite a while now, I have been a bit of a mad scientist on my DC's.
I thought it would be a great idea to start a thread with a few of the mods I do on them.
Maybe we'll get lucky and enough people will chime in to get it made 'Sticky!'
These are the mods that I get asked about the most. I usually give the info away, as they are pretty easy and I figure everybody deserves to have their amp sounding the best that it can. Some of these I came up with, some of them are from other members here who have been gracious enough to share them with me.
Series Loop Mod: (I think this came from MJ Slaughter, hope he doesn't mind me sharing)
This basically changes the amp's FX Loop from parallel (which I hated with delays) to series.
I have a drawing for it, but it's a pdf and I don't know how to post it here. Plus, I don't have a long term way of posting it. Maybe someone can chime in and help with this.
Adjustable Bias Pot:
In the middle of page 5, you will see the Bias Supply.
Remove the 22k ohm resistor that leads to ground.
If I remember right, it's located on the lower left hand side of the board if the front of the chassis is facing away from you.
I use a standard 10 k ohm Bias Pot for a Fender amp: http://www.tubesandmore.com/scripts/foxweb.dll/catalog@d:/dfs/elevclients/cemirror/ELEVATOR.FXP?PAGE=SUBCAT&SEARCH_TREE01=08_POTENT&SEARCH_TREE02=05_FENDERRE&SEARCH_TREE03=03_FOB
Their search engine was down when I tried it, but look for 'Original Fender Bias Potentiometer.'
I twist about 6" of wire together. I usually use 20 gauge wire.
I put 2 pieces of different colored wire in my drill and twist the hell out of it so that it is nice and tight and it looks like it was meant to be that way.
Then, I solder one end of the 2 wires to the solder tabs where the resistor used to be.
Make sure you know which one is ground. That will usually be the end that was toward you, but I've seen quite a few board revisions.
Place the pot in the 'Mix' pot's hole.
Solder a 15k ohm resistor from the Middle tab to the housing of the pot.
Solder the Ground wire to the housing of the pot.
Solder the remaining wire to one of the outside tabs of the pot.
If the pot seems to turn backwards, simply swap the wire to the other outer tab.
This works really well. But, make absolutely sure that your solder connections are good. Failed Bias can kill your amp quickly.
Master Volume mod: (not sure who told me about this one)
There will be a resistor in parallel with the Output Volume pot.
It is a 220k ohm 1/2 watt resistor.
Some older amps have them soldered directly to the pot.
Others have them placed directly behind the pot on the circuit board.
Make sure to use an ohm meter so that you don't accidentally cut the wrong resistor.
Simply snip it off or un-solder it from the board, that's it.
This will make the Output Volume have a much better taper and make it much more user friendly at lower volumes.
Footswitch mod: This one is a bit complex, but really makes the DC 'A' series much more useable on stage.
This mod makes the front footswitch jack on the 'A' series control the Channel Switching and the EQ!
You will need:
15" of shielded single conductor wire
1 - Stereo jack, insulated : http://www.tubesandmore.com/scripts/foxweb.dll/moreinfo@d:/dfs/elevclients/cemirror/ELEVATOR.FXP?item=S-H601B
There are 2 ways to do this mod, the 1st of which is much more simple.
1. Simply remove the Reverb wire from the Reverb/EQ footswitch jack.
It is the middle tab usually.
Then, run the shielded cable from the middle tab on the jack to the front footswitch jack.
The tab that you will solder to on the front jack is the 'Tip.' You will see a grey or white wire going from it to the board.
That's it!
2. Remove the front footswitch jack.
Drill the hole larger so that your new insulated jack will fit.
Install the new jack. You will need 2 of the fiber washers that the jack comes with, so buy
an extra one. It only comes with 1.
Run the shielded wire from the 'Tip' of the Reverb/EQ jack to the middle of the new jack.
Replace the existing channel switching wire on the 'Tip' of the new jack, and the black ground
wire will go on the solder tab that is closest to the front of the chassis.
That's it!
You have to use shielded wire or your amp will hum like a motha.
You have to use an insulated jack or your amp will hum.
You have to ground only 1 side of the shield or your amp will hum.
I usually ground it at the side it starts from, the jack on the back.
Before you start, make absolutely sure that you know what you are doing and you know how to discharge caps.
The voltages in your amp can kill you or someone around you. I got careless once and it hurt so bad that it will never happen again!
http://www.aikenamps.com/SafetyTips.html
Anybody else have a few that are favorites?
I thought it would be a great idea to start a thread with a few of the mods I do on them.
Maybe we'll get lucky and enough people will chime in to get it made 'Sticky!'
These are the mods that I get asked about the most. I usually give the info away, as they are pretty easy and I figure everybody deserves to have their amp sounding the best that it can. Some of these I came up with, some of them are from other members here who have been gracious enough to share them with me.
Series Loop Mod: (I think this came from MJ Slaughter, hope he doesn't mind me sharing)
This basically changes the amp's FX Loop from parallel (which I hated with delays) to series.
I have a drawing for it, but it's a pdf and I don't know how to post it here. Plus, I don't have a long term way of posting it. Maybe someone can chime in and help with this.
Adjustable Bias Pot:
In the middle of page 5, you will see the Bias Supply.
Remove the 22k ohm resistor that leads to ground.
If I remember right, it's located on the lower left hand side of the board if the front of the chassis is facing away from you.
I use a standard 10 k ohm Bias Pot for a Fender amp: http://www.tubesandmore.com/scripts/foxweb.dll/catalog@d:/dfs/elevclients/cemirror/ELEVATOR.FXP?PAGE=SUBCAT&SEARCH_TREE01=08_POTENT&SEARCH_TREE02=05_FENDERRE&SEARCH_TREE03=03_FOB
Their search engine was down when I tried it, but look for 'Original Fender Bias Potentiometer.'
I twist about 6" of wire together. I usually use 20 gauge wire.
I put 2 pieces of different colored wire in my drill and twist the hell out of it so that it is nice and tight and it looks like it was meant to be that way.
Then, I solder one end of the 2 wires to the solder tabs where the resistor used to be.
Make sure you know which one is ground. That will usually be the end that was toward you, but I've seen quite a few board revisions.
Place the pot in the 'Mix' pot's hole.
Solder a 15k ohm resistor from the Middle tab to the housing of the pot.
Solder the Ground wire to the housing of the pot.
Solder the remaining wire to one of the outside tabs of the pot.
If the pot seems to turn backwards, simply swap the wire to the other outer tab.
This works really well. But, make absolutely sure that your solder connections are good. Failed Bias can kill your amp quickly.
Master Volume mod: (not sure who told me about this one)
There will be a resistor in parallel with the Output Volume pot.
It is a 220k ohm 1/2 watt resistor.
Some older amps have them soldered directly to the pot.
Others have them placed directly behind the pot on the circuit board.
Make sure to use an ohm meter so that you don't accidentally cut the wrong resistor.
Simply snip it off or un-solder it from the board, that's it.
This will make the Output Volume have a much better taper and make it much more user friendly at lower volumes.
Footswitch mod: This one is a bit complex, but really makes the DC 'A' series much more useable on stage.
This mod makes the front footswitch jack on the 'A' series control the Channel Switching and the EQ!
You will need:
15" of shielded single conductor wire
1 - Stereo jack, insulated : http://www.tubesandmore.com/scripts/foxweb.dll/moreinfo@d:/dfs/elevclients/cemirror/ELEVATOR.FXP?item=S-H601B
There are 2 ways to do this mod, the 1st of which is much more simple.
1. Simply remove the Reverb wire from the Reverb/EQ footswitch jack.
It is the middle tab usually.
Then, run the shielded cable from the middle tab on the jack to the front footswitch jack.
The tab that you will solder to on the front jack is the 'Tip.' You will see a grey or white wire going from it to the board.
That's it!
2. Remove the front footswitch jack.
Drill the hole larger so that your new insulated jack will fit.
Install the new jack. You will need 2 of the fiber washers that the jack comes with, so buy
an extra one. It only comes with 1.
Run the shielded wire from the 'Tip' of the Reverb/EQ jack to the middle of the new jack.
Replace the existing channel switching wire on the 'Tip' of the new jack, and the black ground
wire will go on the solder tab that is closest to the front of the chassis.
That's it!
You have to use shielded wire or your amp will hum like a motha.
You have to use an insulated jack or your amp will hum.
You have to ground only 1 side of the shield or your amp will hum.
I usually ground it at the side it starts from, the jack on the back.
Before you start, make absolutely sure that you know what you are doing and you know how to discharge caps.
The voltages in your amp can kill you or someone around you. I got careless once and it hurt so bad that it will never happen again!
http://www.aikenamps.com/SafetyTips.html
Anybody else have a few that are favorites?
