DC Mods that are easy to do!

[BobR]

Not sure. Recheck all your work. Took me a lot of trial and error to come up with a simple bias mod for the amp myself. Patience is key.

What is wrong with the stock loop? I use mine all the time no problem with GEQ's and an Ibanez DE7. Bob

 

[boogietone]

Fixed the DD-3. I just went through it and touched up all the solder joints. Didn't think it would work but it did. The solder joints
especially where the ac power supply comes in looked pretty shady. Also, modded the EFX loop back to serial. Might have a DD-6
for sale soon. I bought that to replace the DD-3. Thanks for all the help.

 

[crguti]

3. There might be an option to do a modern voicing mod on the gain-channel, i will test this and post the results.

@Monster-tone: the 470k input resistor on the gain-channel is not a fundamental part of that channel. To be precisely, the 1M 500pf combination of the clean channel is still active when the gain channel is activated and the additional 470k in parallel will indeed result in a 391k 500pf combination. This may sound dull. One could remove it or replace it with a 5M resistor.


Max

so, anyone has tried that?

 

[evilpresence]

Finally bought my own house so I can play at a more reasonable level than 0.5 on the master output. Cranked her up to 1 and the whole house shook so I went for the volume mod and snipped the resistor off. It's a bit more user friendly from 0.5 to 1.5 but anything past 1.5 I should probably wear ear plugs.

I saw on this thread http://forum.grailtone.com/viewtopic.php?f=28&t=51608 that some are playing above 5 on the output. No way in hell I am able to do that.

Is there something I am missing?

 

[bhsbhswarp]

If you can't get the amp past 1.5 your not even using it..

 

[evilpresence]

If you can't get the amp past 1.5 your not even using it..

Thank you for the constructive response but I was looking for something a little different. I am not joking when I say having the master output at 1.5 is like I'm at a show standing right next to the speakers. I've always thought that is just how the amp is, since I've had it for 9 years. Living in an apartment or twin house does not allow me to even test it at higher volumes. Like I said in the previous post, since I bought a SFH, I now can turn it up a bit. Before I was using an attenuator but didn't like the sound it was producing.

My master output is a 1 Meg pot. Is that what everyone else has? Maybe I need to resolder the master output contacts...

 

[Monsta-Tone]

Not sure what an FSH is, sorry.

As for the amp....
1 Meg Audio taper is the correct pot. If it's too loud, re-soldering the connections will do nothing.

I would look for a DC-2 with the Contour or a DC-3, although they will be loud as well.

Something that I've seen a lot of guys do is use a plexi-glass cage around it or a shield in front of it to make it more bearable.
You could also try a Weber Beam Blocker.

You could call The Tube Store and ask them for a set of 6L6's that will break up sooner and still fit in your bias range. That would probably be the best method. That way you can get the amp cooking a little more at lower volumes.

Honestly, this amp is made to play with a band. It doesn't even start to sing until you get the volume past 1.5!

 

[MJ Slaughter]

Honestly, this amp is made to play with a band. It doesn't even start to sing until you get the volume past 1.5!

Exactly. I've always had to have my DC amps at least slightly past 2, 3 - 4 better, to get the best sound out of them. If I were an at home player only I'd most likely just use a good modeler or a 5 watt amp. Unfortunately even at 2-3 on the level out and 4-5 on the channel masters it can be too loud for many stages I play on.

 

[bhsbhswarp]

If you can't get the amp past 1.5 your not even using it..

Thank you for the constructive response but I was looking for something a little different. I am not joking when I say having the master output at 1.5 is like I'm at a show standing right next to the speakers. I've always thought that is just how the amp is, since I've had it for 9 years. Living in an apartment or twin house does not allow me to even test it at higher volumes. Like I said in the previous post, since I bought a SFH, I now can turn it up a bit. Before I was using an attenuator but didn't like the sound it was producing.

My master output is a 1 Meg pot. Is that what everyone else has? Maybe I need to resolder the master output contacts...

you may have a bad pot there.My DC3 at 1.5 on the output is very good for bedroom noodling.
I use th master output at about 2 1/2 and the channel master way down around 1 1/4.I did'nt mean to sound nasty in my post, it's just the amp does'nt do much until you crank it past 2 or 3. My master output pot is 100kL linier.The channel masters are 25KL.It's possible someone modded it,the schematic calls for 100k,not 1 meg.

 

[needsmoregear12]

Im a bit late here but...

Could somebody please email me the effects loop mod and maby some more info on the master volume mod?
I might be picking up a DC10 in about a week or two.

Email: [email protected]

Thanks in advance

 

[Monsta-Tone]

Look here: http://forum.grailtone.com/viewtopic.php?f=28&t=58252
There is a link to the drawing.

 

[AshokanKid]

Hi;

Is there perhaps some common repository or hosting page for all of these DC mods in one place?

Thanks;

AK

 

[Maynardo]

the 1M 500pf combination of the clean channel is still active when the gain channel is activated and the additional 470k in parallel will indeed result in a 391k 500pf combination. This may sound dull. One could remove it or replace it with a 5M resistor.

:shock: Is this right?. I don't get it, how can the input from the first stage of the clean channel still be active when you are in the lead

 

[BlackBoxy]

Hello,

there is a lot of misleading information in this thread so i will post the results of my current DC-5a modification here, perhaps it will be of some help to someone in the future.

1. Bias mod: It is possible to replace the 22k resisitor, but i would recommend to built it fresh (i will post pictures and schematics on request). It's a typical Smith-circuit and the 220uF capacitor is rated 63Vdc, with around -70Vdc after the 1K/(22k parallel 82k) voltage divider! Mine is still working, but i recommend to replace that capacitor with a 100V type (100uF is still enough).

2. Power-tubes: without the biasmod talking about Power-tubes doesn't make sense. The PT is a 561155 also used in the rectoverb so it's safe to say that there is enough reserve regarding the heater current. My DC-5a is working with 5881, 6L6 (-43V) and EL34 (-38V). I recommend to measure the cathode-current over a 1Ohm resistor (info everywhere on the net) and bias to ca. 70% of Pmax.

3. There might be an option to do a modern voicing mod on the gain-channel, i will test this and post the results.

@Monster-tone: the 470k input resistor on the gain-channel is not a fundamental part of that channel. To be precisely, the 1M 500pf combination of the clean channel is still active when the gain channel is activated and the additional 470k in parallel will indeed result in a 391k 500pf combination. This may sound dull. One could remove it or replace it with a 5M resistor.


Max

great quote and mod, and i don't konw why Mesa added this parallel 470k to 1M input of clean channel! 1/10 impedance or circuit laws? not really!

it kills all attack and harmonics, i removed it , seems a carpet went off this amp and without adding hights or loosing gain!

thx MAX

 

[Maynardo]

great quote and mod, and i don't konw why Mesa added this parallel 470k to 1M input of clean channel! 1/10 impedance or circuit laws? not really!

it kills all attack and harmonics, i removed it , seems a carpet went off this amp and without adding hights or loosing gain!

thx MAX

So it does work!, did it affect both channels?.

 

[BlackBoxy]

great quote and mod, and i don't konw why Mesa added this parallel 470k to 1M input of clean channel! 1/10 impedance or circuit laws? not really!

it kills all attack and harmonics, i removed it , seems a carpet went off this amp and without adding hights or loosing gain!

thx MAX

So it does work!, did it affect both channels?.

it works , but a 2 to 5M resistor "depend of yourtaste" replacement would be better than nothing, because it makes tone stack a lil too boomy

 

[Maynardo]

it works , but a 2 to 5M resistor "depend of yourtaste" replacement would be better than nothing, because it makes tone stack a lil too boomy

I personally really like the way lead channel sounds on it's own and the clean channel too, the problem is they don't mix well together, when you go from clean to lead in the same song it does seem like there's something holding back the pick attack and volume in the lead in comparison to the clean side.

When I saw what you posted, I thought... hey maybe this it! now they'll mix well together .

I don't really see how could it get boomy tho, shouldn't be the opossite?... I mean with higher inpedance in the input should get brighter not boomier, right?

 

[joemarshalljmp]

Hello new dc 10 owner, I have an old one with no half switch, I have looked but didn't find any info, is there a half switch mod that I can do, or is it safe to pull two tubes? That thing is loud and the vol pot is touchy! Please help or direct me to the help thanks!!

 

[Maynardo]

New choke mod

Based on this:

Your amp has a choke. There is a 5 watt, 1k resistor in parallel with it though. You could most likely remove this resistor and completely change the dynamics of the amp. I have been thinking of this, but have never had the time to do so.

Mesa uses the same choke on their 50 & 100 watt amps, so it should be perfectly safe to do.

I have changed DC-5 chokes to Mercury Magnetics chokes and had a slight increase in sustain and smoothness.


Let me know if you try this. I've always been curious.

I took the resistor out and it is a KILLER MOD, the bass improves in every posible aspect, it's now clearer & tighter , also the amp cleans better in the lead channel when using the volume pot in the guitar.

I have no idea why did Mesa put that thing in there, maybe a failsafe or what not, maybe to stop the stand-by switch from poping, but it's clear that a good portion of the filtering was being done by the resistor.

My amp is a DC-5A, to find the resistor look for a big white one, it's marked 1.5k , almost next to one of the orange leads coming from the choke close to V3, you can check continuity with both leads to make sure it's the parallel resistor, just take it out and you're done. It's a simple mod more so than the output volume mod, since you have no big capacitors near. Bare in mind after the mod, the stand by switch pops.

 

[edward]

Hmmm, interesting. I have a DC5A and love what it does for me (my #1 go-to live amp for over a decade). That said, "cleaning up better" with the guitar's vol knob on the OD channel is always interesting. Questions if you please:

1. Any tonal affect that you can hear on the clean channel?
2. Any effect on the timbre/character of the OD channel other than more bass?
3. How bad is this pop with the standby switch? Any risks of damage to the speaker?
4. Got a pic? ...I'd love to see exactly what resistor you're talking about?

To anyone here, (especially Andy!!), what exactly is the function of this resistor in this circuit? Anyone with understanding of these boogies care to speculate why they put it in there .... they've got to have a reason, no?

Thanks ...looking forward to more on this one

Edward