DC Mods - Revisited...........Sort of.............

DC-2, 3, 5, 10
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Monsta-Tone
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DC Mods - Revisited...........Sort of.............

Post by Monsta-Tone » Sat Feb 04, 2012 12:37 pm

Well...I've come full circle and have now been playing a DC instead of my Heartbreaker.
I thought I should revisit the DC Mods thread, but it seemed easier to just start over.
I have moved back to Maui and shipping is not really an affordable option for most of us here, so it is my hope that these mods will help someone to find their tone!
Maybe this will be made a "Sticky" so it stays easy to find!

Here is a list of my favorite easy mods for a DC.
This is more aimed at the 5 & 10, but most of them will work very well for a 2 or 3 with the exception of the Phase Inverter mods.
The Lead channel on my DC-5 is completely different from these mods. Not sure I want to share that one just yet. It's extremely involved. Basically, the entire channel is reconfigured.

I can provide minimal tech support for these mods, but simply don't have time to walk everyone through them, sorry.


Blanket Removal Mod:I always seem to forget to tell people about this one, but it makes a huge difference. It gets rid of a lot of the muddy tone and over all lack of dynamics compared to some of the Holy Grail amps.
1. Right after V6 (page 7 of drawing), there is a 75pf cap that ties pins 1 & 6 of V6 together.
Replace this cap with a 47pf Silver Mica cap.

2. Then, remove the 2 120pf caps across the 82K & 100K resistors that are located just to the Right of the 75pf cap.
These caps are placed here to eliminate oscillation and feedback.
I play a JS1000 (basswood body) and after this mod, I can get that perfect "Flying in a Blue Dream" feedback and sustain.
Last edited by Monsta-Tone on Sat Feb 04, 2012 1:47 pm, edited 1 time in total.
Elvis said.......
Amp techs do get shocked. :shock:

Monsta-Tone
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Re: DC Mods - Revisited...........Sort of.............

Post by Monsta-Tone » Sat Feb 04, 2012 12:39 pm

Better Reverb Mod:
1. Dwell or Speed of Reverb...To change the Dwell of the Reverb, experiment with the 1M resistor that ties Pin 2 of V5A to ground (Grid Resistor).
I like 680K or 750K a little better than the 1M. It slows the Reverb repeats down a little bit and makes it a little more Fender like.

2. Different response....There is a .002 cap from Pin 1 of V5A to ground. Move the side of the cap that goes to ground to Pin 3 of V5A.This should make the Reverb a little better sounding and change the feel of it a bit.

3. Stronger Reverb....On page 6 of the drawing, you will see a 22k resistor in series between the B+ voltage and the Red wire of the Reverb Transformer. This is placed here to prolong the life of the transformer.
You can experiment here with different values of resistors. I usually knock it down to a 5K 1 watt resistor. Removing it completely will probably put you into Dick Dale territory.
I always use a 1 watt resistor here. I have had a few 1/2 watt resistors fail.
Last edited by Monsta-Tone on Sat Feb 04, 2012 1:48 pm, edited 1 time in total.
Elvis said.......
Amp techs do get shocked. :shock:

Monsta-Tone
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Re: DC Mods - Revisited...........Sort of.............

Post by Monsta-Tone » Sat Feb 04, 2012 12:55 pm

Lead Channel Mods
More or Less Gain:
Between V1B & V2A there is a Voltage Divider (page 5 of the drawing).
You will see a 150K resistor going from the signal path to ground. Change this resistor.
Lower value = Lower gain
Higher value = More gain
I like 220K. 330K is really nice too, but starts to get a little bit mushy.
Any more than this and it gets really mushy but has gobs of gain.

Tone Stack Mods:
Right after V3A is the Tone Stack. The DC lead channel has 2 tone stacks, but this is the one that is adjustable with the pots.
1. The stock Tone Stack resistor is 82K. Changing this resistor will change the overall frequency response of the Tone Stack.
Lower value = More Bass
Higher value = Less Bass
I like 56K or even 47K if the speaker is really bright.
This mod really depends on the speakers you are using. I use the C-90 in my DC-5 combo, so I like 56K the best. When I used Vintage 30's, I went down to 47K.
If the amp is too dark for you, then you can go as high as 100K, but you might try the next mod 1st.

2. Change the 500pf Ceramic Disk capacitor (Treble Cap) in the Tone Stack to a 500pf Silver Mica. This will really help give it a little more of a Modern tone. I like Silver Mica caps much better than Ceramic Disk because they seem to not stomp on the highs as much. Some people think they are too "Hi-Fi" sounding and not as "Vintage" sounding. There is no right or wrong, it's your amp!

You can dramatically change the way the Lead channel acts with this cap. It affects the Treble, but more importantly, it affects the Upper Mid Range!
Higher value = More Upper Mids
Lower value = Less Upper Mids
I really like 500pf, but 750pf or even a .001mf will dramatically change the entire channel!
This mod becomes much more apparent, and the Mid pot becomes more aggressive as the Treble is turned up.

The Clean channel has a great example of this in the Push/Pull Boost on the Gain pot.
It also bypasses the Tone Stack, which is why you have the huge volume jump when the pot is pulled out.
Last edited by Monsta-Tone on Sat Feb 04, 2012 1:48 pm, edited 1 time in total.
Elvis said.......
Amp techs do get shocked. :shock:

Monsta-Tone
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Re: DC Mods - Revisited...........Sort of.............

Post by Monsta-Tone » Sat Feb 04, 2012 1:09 pm

Clean Channel Mods:
This one is really subjective! It seems like most of the people I do amp work for have dramatically different ideas of what a great clean sound is.

Here is what I did to my amp, most of it anyway. I like very huge, warm cleans with lots of sparkle and just a little bit of grit.
My amp is the B version, so the A version may not sound the same since it already is more gritty than the B.

V1A
Change the 1mf cap from Pin 3 (Cathode) to ground to a 15mf = adds more bass
Remove the .001mf cap from B+ to Pin 1 (Plate) = adds back a lot of upper frequencies that are attenuated by the cap
Change the 150K resistor from B+ to Pin 1 to a 100K = lowers the overall gain a little bit for the channel, seems to give a little more clean headroom

Tone Stack
Change the 150K Slope Resistor to 100K = Gives you more of a Twin Reverb type of tone, larger and more depth
Change the 250pf and .002pf caps (Treble & Mid Boost) from Ceramic Disk to Silver Mica = adds more Presence and upper highs
Change the .1mf & .047mf (Bass & Mids) to 715P Orange Drops (I like the 400 volt versions here because they are much smaller than the 600 volt) = Really opens up the sound and makes it more full

The Orange Drops don't fit very well. I make them a bit taller so that I can reach in there with an iron.
I also add a dab of silicone to keep them from vibrating too much.

V4A
Remove the 47pf capacitor that goes from Pin 2 (Grid) to ground = This will add back a lot of sparkle
Add a 15mf cap from Pin 3 to ground = This really boosts the bass and adds a little bit of gain back in that we got rid of in V1A


Overdriven Cleans:
After all of that, if the owner wants more of a dirty Blues type of clean, I do the following:

V4A
Change the 330K resistor from Pin 2 to a 680K or 1M
Bigger Resistor = More Overdrive
Smaller Resistor = Less Overdrive

Series Resistance
Between V4A and the Master pot you will see a 330K resistor in Series with the signal.
Change this to a 220K to allow more signal to pass through.

Master Volume
Change the Master Volume from a 25KL to a 1MA pot. This will allow more signal to pass into the next stage and shunt less to ground.
Elvis said.......
Amp techs do get shocked. :shock:

Monsta-Tone
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Re: DC Mods - Revisited...........Sort of.............

Post by Monsta-Tone » Sat Feb 04, 2012 1:44 pm

Finally.....The Standard mods

Loop:
Polaris20 was kind enough to host this on his site: http://biesiadecki.org/wp-content/uploa ... oopMod.pdf
This will turn the Loop to Series instead of Parallel, which is much better sounding to most people for using Delays and other time based FX in the Loop.

I like to go a couple of steps farther:
I replace the Send Jack with a Switchcraft 12A switching jack. Now that the Loop is Series, the entire signal will pass through the switching mechanism in the Send Jack.
The ones that Mesa uses are good quality, but these jacks are at least 10 years old and I figure it can't hurt to go the extra mile.

I also remove the Mix pot completely and use the hole for something cool like a bias pot or Negative Feedback switch.


Output Volume Mod:
This mod basically removes the 220K resistor that is placed in parallel with the input and the wiper of the Output Volume pot.
The reason for this mod is to make the amp much more user friendly at lower volumes.

I take this one a step farther.....
I replace the pot with Mesa part # 591842 (Same pot as the Clean Channel Gain pot)
It is a CTS push/pull 1M audio pot that has a different taper. The taper on the stock pot is fairly linear. When the amp is on 2.5 or 3, the resistance between the input and the wiper goes from 1M to about 850-830K. This is where the huge volume jump happens!

The taper on the CTS pot is far less linear. The amp is basically at noon by the time it reaches the same resistance reading as the stock pot.
This gives you a lot more control of the lower volume range!

Then......I add the 220K resistor back in with the Push/Pull portion of the pot.
Basically, it is out of the circuit when the pot is pushed in.
It is in the circuit when the pot is pulled out.
The volume jump is extremely dramatic! My thoughts are that larger gigs and outdoor venues might benefit from the Pull Function!



Anyway.....
That is about it. Hopefully someone will benefit from this!
Please be extremely careful & discharge the caps! It f%&# hurts if you get sloppy and forget to discharge them! I've done this twice now! I get in a hurry and forget to discharge them or leave the amp plugged in and knock the crap out of myself.
Also, if you aren't familiar with soldering irons and not very handy with tools, it is my hope that you will hire someone to help! I've seen way too many amps with burned wires, pulled traces, missing traces, etc. because someone tried to do something that they maybe weren't ready for.........

I would definitely take my time and do 1 mod at a time and the try the amp out to see if you like them.
It's all too easy to do a bunch of stuff to an amp and then not like it or even worse, the amp isn't working and you just don't know where to start figuring out what went wrong! I've wasted days of labor on tracking down the wrong part or a bad solder connection, etc.........it sucks!

Lastly......
I use a meter and measure every part before installing it. One time I grabbed an 82K resistor instead of an 820 ohm resistor because one of the stripes was missing. The owner of a very beat up, but incredible sounding 1970 Marshall Tremolo head was very mad at me! He brought his amp in for a cap job and new input jacks and it just sounded like dirt afterward. Needless to say, I chased my tail for days thinking that I had done something wrong or the amp had an issue that he didn't tell me about. All I had to do was check my parts before I installed them.
Elvis said.......
Amp techs do get shocked. :shock:

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Re: DC Mods - Revisited...........Sort of.............

Post by Nomad100 » Sat Feb 04, 2012 5:07 pm

Fantastic post. I'm planning on firing up the soldering iron and trying some of these mods on my DC-5b soon.

Thanks :D

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Re: DC Mods - Revisited...........Sort of.............

Post by boogietone » Sat Feb 04, 2012 6:51 pm

Thanks Monsta-tone! One question, where is the drawing you referenced?
Thanks again!
Guitars: HamerUSA T-62 and Centaura
Amp: Mesa DC-5a
EFX: Boss SD-1, DD-3

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Re: DC Mods - Revisited...........Sort of.............

Post by Monsta-Tone » Sat Feb 04, 2012 6:55 pm

Elvis said.......
Amp techs do get shocked. :shock:

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Re: DC Mods - Revisited...........Sort of.............

Post by jpdennis » Sat Feb 04, 2012 9:09 pm

There is a young man looking to get his first Boogie - DC-10. Will this work for the DC-10 as well as the DC-5? Also, he should have contacted you about this already.

Dennis
Mark III no mark w Randy's initials & some IIc+ parts
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Heartbreaker
Fender 75
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1970 LPGT
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1983 (Elite Neck)/2001 FrankenStrat
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more guitars, so little characters

needsmoregear12
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Re: DC Mods - Revisited...........Sort of.............

Post by needsmoregear12 » Sat Feb 04, 2012 11:10 pm

jpdennis wrote:
There is a young man looking to get his first Boogie - DC-10. Will this work for the DC-10 as well as the DC-5? Also, he should have contacted you about this already.

Dennis
Youve beat me to it on this thread ;)

I posted on the old thread of DC Mods. Im very interested in the Effects loop mod aswell as the Output volume mod. Since Im a heavy delay user and im a bedroom rocker during the week, the amp will shine on the weekends though ;)

I wanted to know how hard these mods are, ive never worked on anything amp related. Besides a tube swap, which really doesnt count :lol:

So if you can please get back to me Id really appreciate it. If you have a layout for the Output Volume mod could you please email it to me? mikemo12@hotmail.com

Thanks in advance :mrgreen:

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Re: DC Mods - Revisited...........Sort of.............

Post by Monsta-Tone » Sun Feb 05, 2012 11:59 am

They are both really simple, and will both work very well for the DC-10.
You will need to solder a little for the loop mod though.
Elvis said.......
Amp techs do get shocked. :shock:

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Re: DC Mods - Revisited...........Sort of.............

Post by boogietone » Sun Feb 05, 2012 12:38 pm

Just completed the EFX loop mod and Master Volume mod on my DC-10. As Monsta-Tone said they are very simple. It takes longer to get the amp out of the chassis than the actual mod. I'd like to experiment with some of the other mods when I have more time and have all the parts. Thanks Monsta for sharing this stuff with us and your expertise.
The DC series are great amps.
Guitars: HamerUSA T-62 and Centaura
Amp: Mesa DC-5a
EFX: Boss SD-1, DD-3

needsmoregear12
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Re: DC Mods - Revisited...........Sort of.............

Post by needsmoregear12 » Sun Feb 05, 2012 3:35 pm

Boogietone: Im glad you think theyre simple enough, now i feel a bit more confident. If i do end up buying the DC10 would you be able to post some pics of where exactly id be working in the amp and what you clipped? Im COMPLETELY new to this stuff so im sure ill be overwhelmed when i open it up.

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Re: DC Mods - Revisited...........Sort of.............

Post by boogietone » Sun Feb 05, 2012 4:59 pm

Sure. I'd be happy too.

However, please be sure to familiarize yourself with all the safety that goes along with poking around inside an amp. There is some pretty serious voltage that can be extremely dangerous/deadly.
Guitars: HamerUSA T-62 and Centaura
Amp: Mesa DC-5a
EFX: Boss SD-1, DD-3

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Re: DC Mods - Revisited...........Sort of.............

Post by needsmoregear12 » Sun Feb 05, 2012 7:53 pm

Ill start reading up on it, and if i do get the DC10 ill message you then.

Thanks in advance, your help is very much appreciated :mrgreen:

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