DC Mods that are easy to do!

[Maynardo]

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

1. it affects both channels in the same way tonally, that means improved bass.
2. nop, but is not "more" bass, it's a "better" bass, cleaner. Made amp sound a bit more "expensive" if that makes any sense.
3. it pops, not a gigantic pop but you'll notice. I'm sure there's other ways to stop the pop without losing the great improvement the choke on it's own gives you.
4. no pics, but believe me it's very easy to find, looks like a plastic white box and it's marked 1.5k as mentioned before.


Cheers

 

[Maynardo]

I remembered I took some gut shots some time ago and it was easy enough to mark the resistor, so here you go:

You can cut one of the leads and see if you like the result.

 

[BlackBoxy]

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

1. it affects both channels in the same way tonally, that means improved bass.
2. nop, but is not "more" bass, it's a "better" bass, cleaner. Made amp sound a bit more "expensive" if that makes any sense.
3. it pops, not a gigantic pop but you'll notice. I'm sure there's other ways to stop the pop without losing the great improvement the choke on it's own gives you.
4. no pics, but believe me it's very easy to find, looks like a plastic white box and it's marked 1.5k as mentioned before.


Cheers

hi,
did it and back padalled, it makes the OD chan bad, adds mud, not really a suprise, this resistor just down tensions on B C D of 12 ax 7 pre!

tonal disconfort for me!

regards

 

[Maynardo]

Wow, the complete opposite to me!, about the resistor 'just down tensions on B C D of 12 ax 7 pre!', the overall ohms went from 88 to 96 between A & B , that's a VERY mild change if you consider for instance that between B and C there are 2.7Kohms and between C and D 17.1Kohms, on the other hand it's easier for current to pass thru a resistor than thu an inductance, so filtering should improve without the resistor.

I was thinking someone once told me he thought the resistor could be there to avoid the amp from resonating, could it be something like the 60hz or 50hz depending on the area thing. Because certanly it does not resonates here, and the bass got super tight great for chugs

 

[BlackBoxy]

Wow, the complete opposite to me!, about the resistor 'just down tensions on B C D of 12 ax 7 pre!', the overall ohms went from 88 to 96 between A & B , that's a VERY mild change if you consider for instance that between B and C there are 2.7Kohms and between C and D 17.1Kohms, on the other hand it's easier for current to pass thru a resistor than thu an inductance, so filtering should improve without the resistor.

I was thinking someone once told me he thought the resistor could be there to avoid the amp from resonating, could it be something like the 60hz or 50hz depending on the area thing. Because certanly it does not resonates here, and the bass got super tight great for chugs

i think you pal was right , for me it blurs especially the Od chan, i'll change it for a better resistor, and i'll try over meanwhile , i got to test winged C, i'll tell you about results!

 

[Maynardo]

if it's resonating you could try upgrading the choke, the guy who modded biggness amp told me he would not remove the resistor unless upgrading the choke to a mercury mc10h , it's like 40 or 50 bucks I think. Anyways since I'm in the other side of the world it's complicated to get it for me, but I went for the resistor anyways, took one lead out tryied it, felt great so I removed it completly.

Cheers

 

[edward]

Hey there guys,

Huge thanks for chiming in on this specific mod I was considering. Hmmm, maybe not, then. I don't really feel like "experimenting" with a mod that may/may not do what I'd like it to do (add a touch of brightness, not gobs, but a bit more for the OD channel; the rhy ch is perfectly fine by me). If there's a reasonable chance I'd need to go in and reverse it (and it sounds like there is), maybe I'll pass. Huge thanks for both of you discussing the point, though ...I appreciate you posting it here!

Edward

 

[jargapix]

Sadly the link to the drawing is down. Can anyone repost it or send it my way? Thanks.

 

[jargapix]

Thanks Monsta!

 

[jpistolas]

Thanks from me as well Monsta! I'm going to be working on a more detailed layout of the loop mod from that drawing. That, along with the other docs you sent should go into a sticky post. Invaluable information. Again, thanks!

 

[boogietone]

Hey everyone, I cut one lead out from that big white resistor Maynardo did. Jury is still out but I like the tone so far. Also, went ahead and did the master volume mod as well. Maybe just my imagination but the amp seems to be running hotter now. Anyone else experience this after the mods or is it in my head? This is a DC-5a BTW. Now, I just need to figure out how to get more reverb out of it. There is no reverb on the lead channel unless the channel master is dimed then you can hear it a little. The clean channel is a little better but barely there as well.

 

[Monsta-Tone]

:mrgreen: :mrgreen: :mrgreen: I didn't realize this thread was still going!

Maynardo.....Now that you've had the resistor that parallels the choke out for a while, how do you like it?
I always thought about removing the resistor, but never got around to it.
Might have to pick up another DC-5 someday soon!!!
I think I would definitely change the choke to a larger one.

 

[boogietone]

What would a larger choke do?

 

[Monsta-Tone]

Actually filter the DC ripple. :lol:
The standard Mesa choke is really small. A larger one should give a smoother tone and a little more horsepower in the sense that it won't bog down in the power supply as much.

 

[BlackBoxy]

I just fitted UF5408 in place to 1n4007 rectifier Diodes , and uf4007 to bias rectifier , this mod brings more life to my dc5 tone, smoother tone ,closer to amp with gz354 rectifier tube ones, lot chimes!

be sure to fit in closely matched diodes

nice mod ..

 

[mysquaredontfit]

I have a DC5B and I'd like to do the blanket removal mod. Could someone point out (in a photo) the location of the 75pf cap I need to replace? This would also obviously key me into the location of the 120pf caps I need to remove, which are described as right next to the 75.

I'm not so great with relating the schematic to the physical layout (yet) and I'm hoping doing this mod will help to keep me from having to spend money on speakers to help brighten/clear up the amp. Thank in advance for any help, this forum and these threads have been great.

 

[BlackBoxy]

I have a DC5B and I'd like to do the blanket removal mod. Could someone point out (in a photo) the location of the 75pf cap I need to replace? This would also obviously key me into the location of the 120pf caps I need to remove, which are described as right next to the 75.

I'm not so great with relating the schematic to the physical layout (yet) and I'm hoping doing this mod will help to keep me from having to spend money on speakers to help brighten/clear up the amp. Thank in advance for any help, this forum and these threads have been great.

on the right side, next to lateral two big orange caps , lower part of the pics, you can see 3 ceramic caps, 2 75pf and 1 120 pf, personaly i removed it , and later recaped it with 45pf ones, removing it brings very little chimes but osciliating noise to power tube, less focused

regards

 

[jpistolas]

Real quick ignorant question on the series loop mod: Once the red & two orange wires are tied they don't have to be connected to the pot any more, correct?

Spent the weekend working on a faulty chorus pedal so before I jump in and finally get to this necessary mod I wanted to be double sure.

Thanks for all the informative posts in this thread.

 

[Monsta-Tone]

Not needed at all. I usually remove the pot and add an adjustable negative feedback or mid boost or something cool......Even a plastic plug in the hole is better than a knob I'll never use....

 

[BlackBoxy]

my best so far mod was replacing all icepeak bright caps ceramics to styroflex 600v 500pf and less along the signal tone stacks, lead and clean chanels!

:shock: :shock:

trebles became smooth and driveable , puts lot chimes on both chanels!

did you try that Monsta?