DC Mods that are easy to do!

[bronzetalon]

Can I also get the .pdf for the series loop mod, my email is [email protected]

New DC-5 owner here shes a bit worn but I got her for $500.

 

[Monsta-Tone]

Done!

 

[MusicManJP6]

...shes a bit worn but I got her for $500.

It's what's on the inside that counts!

 

[Judas]

hello, I'm interested too in the serial effect loop mod. I send you my email adress in a private message.

 

[silentrage]

So what's the range of the bias current with the above mod?

 

[LTE]

Probably this summer i will look into the volume mod, how big is the difference?

I mean i usually always use my attenuator when im playing in my room, and i have the master volume at 4.5, and clean i use the attenuator off and master at 1.5


Also, regarding the boost on the rhy channel. I think it would be good if it was footswitchable, but i think it just adds alot more variety. Playing live with my band i usually have the rhythm on a clean, jazz tone, and then pulling that instantly sounds like Pete Townsend rhythm and i use my tubescreamers to get into a controllable slicing blues tone.
I love it and hate it, but the boosted rhythm has so much more punch than the lead channel, but the lead channel cuts through a mix so much better.

 

[MusicManJP6]

Probably this summer i will look into the volume mod, how big is the difference?

It smooths out the taper in the lower end of the volume output (below 2). If you always use an attenuator and the output is at 4.5 then you prob won't notice a difference. It's VERY easy to do though. The hardest part is pulling the chassis and that's not really that hard - you just have to be careful and patient and take your time.

 

[Monsta-Tone]

Apparently, I didn't write it down, but I seem to remember that the range of the pot is + or - 20 ma.
It may not be that much, but that's the number that sticks in my head.
This is plenty since nobody here (myself included :lol: ) has been brave enough to stick some EL-34's in yet.

The DC-5 has the same power transformer as the Nomad 55 which has the EL option, so I'm guessing it will be safe.


The range will also be affected by your tubes and the characteristics of the set that you have installed.
Some tubes just come in way too high or low on the range to bias up properly.

 

[MJ Slaughter]

Monster-Tone, Master of Mods, do you have anything to mod my now series FX loop on my DC-10 to be foot switchable? I'm going to get something like the Axess CFX4 to change channels, EQ, reverb and FX loop if I can do a mod.

 

[Monsta-Tone]

I'm working on it. So far though, I don't like the results.
I need to make it more quiet and make sure it doesn't suck any tone!

 

[LTE]

I have a DC5 with the rotary eq switch on the back only, and the lead/rhythm 2way switch on the front.

I only have a lead/rhythm footswitch, but can i safely plug that into the eq/on/off fswtch input on the back??

 

[Monsta-Tone]

You can safely plug it in as long as it is not powered in any way.

The problem is, that this jack is for 2 switches.
It may be that your Reverb won't work.
It may be that it will switch the Reverb instead of the EQ.
It may be that the Reverb is not affected and the EQ switches fine.

If it doesn't work right, you might be able to pull it out 1 click. It should click 3 times when you plug it in.

 

[silentrage]

Apparently, I didn't write it down, but I seem to remember that the range of the pot is + or - 20 ma.
It may not be that much, but that's the number that sticks in my head.
This is plenty since nobody here (myself included :lol: ) has been brave enough to stick some EL-34's in yet.

The DC-5 has the same power transformer as the Nomad 55 which has the EL option, so I'm guessing it will be safe.


The range will also be affected by your tubes and the characteristics of the set that you have installed.
Some tubes just come in way too high or low on the range to bias up properly.

What's a typical bias setting for a stock DC-5? If it's +-20ma would you say it's safe to crank it one way or the other without seriously damaging anything?
I'm guessing you probably have a bias probe that helps you stay in the safe zone, I should probably get that, hehe.

And did you notice a huge tonal difference?

I heard bob from Eurotubes offers KT66s for DC-5s, those are just a variation of EL34 right? If that's the case then I think you could pop some in without much issues.

 

[Monsta-Tone]

The problem with setting the Bias and not checking the Plate Voltage is this:
The Bias Current is supposed to be set at a certain ratio to the Plate Voltage to achieve 70% Plate Dissipation, give or take 5% or so.

It's not exact, and here's why:
Every set of tubes you get, unless they have been tested and fall within a specific range of current draw, will have a different effect on the amp.
Mesa (and the guys who sell Mesa replacement kits - most of them anyway) run their tubes through a 'Characterizer' or other machine that tells them what the current draw, plate voltage, bias current will be for a given situation.
This is how they can sell you a set of tubes that are simply 'Plug-n-Play.'

Unfortunately, I really don't like the tones that current Mesa power tubes have to offer and I don't think I should pay that much for tubes, not even NOS.


I use this tool: https://taweber.powweb.com/biasrite/br_page.htm

That way I can make sure that the tubes are drawing the proper amount of current.
To me, it's really important to check the Plate Voltages several times while biasing the amp. They will change as you change the Bias Current.



As for tonal differences between a properly biased amp and one that is biased poorly...
I find that the amp feels more alive when you play it. Also, it removes a lot of the 'Blanket' that some people hear. And, it seems to increase the available headroom if the amp is biased properly.

I think one of the main reasons that Mesa biases their amps on the cold side is to make sure that the tubes last longer.
They are in the business of selling reliable, kick ass amps. Last thing they want is their customers saying, 'It sounds great, but man does it eat tubes...'

 

[eiopago]

Hello,

this comes really handy as I was lloking for it.
Can someone please email me any information on the effect loop mod?

my email is: [email protected]

thanks in advance

Marco

 

[Monsta-Tone]

Done!

 

[MJ Slaughter]

I'm working on it. So far though, I don't like the results.
I need to make it more quiet and make sure it doesn't suck any tone!

Hey Monsta. I had asked you about a foot switchable FX loop before, you response above, and was wondering if you are thinking that I want it totally disengaged like the switch on the Stiletto will do. I would be happy with something that would act like nothing was plugged into the send and returns at the press of a switch. Doesn't need to be taken out of the circuit. Is that still a problem or does it become easier? Thanks.

 

[Monsta-Tone]

That should make it a lot easier.
The problem with the other way is that the eq is the input stage for the loop and was creating quite a problem trying to leave it in while taking the loop out.



I won't be able to work on amps til next weekend. Send me a reminder pm or email next Friday and I'll take a look at it.

 

[silentrage]

The problem with setting the Bias and not checking the Plate Voltage is this:
The Bias Current is supposed to be set at a certain ratio to the Plate Voltage to achieve 70% Plate Dissipation, give or take 5% or so.

It's not exact, and here's why:
Every set of tubes you get, unless they have been tested and fall within a specific range of current draw, will have a different effect on the amp.
Mesa (and the guys who sell Mesa replacement kits - most of them anyway) run their tubes through a 'Characterizer' or other machine that tells them what the current draw, plate voltage, bias current will be for a given situation.
This is how they can sell you a set of tubes that are simply 'Plug-n-Play.'

Unfortunately, I really don't like the tones that current Mesa power tubes have to offer and I don't think I should pay that much for tubes, not even NOS.


I use this tool: https://taweber.powweb.com/biasrite/br_page.htm

That way I can make sure that the tubes are drawing the proper amount of current.
To me, it's really important to check the Plate Voltages several times while biasing the amp. They will change as you change the Bias Current.



As for tonal differences between a properly biased amp and one that is biased poorly...
I find that the amp feels more alive when you play it. Also, it removes a lot of the 'Blanket' that some people hear. And, it seems to increase the available headroom if the amp is biased properly.

I think one of the main reasons that Mesa biases their amps on the cold side is to make sure that the tubes last longer.
They are in the business of selling reliable, kick ass amps. Last thing they want is their customers saying, 'It sounds great, but man does it eat tubes...'

Thanks for the detailed reply! I think I'm gonna try the bias mod.
I find the DC-5 lacks tightness in the bottom and headroom, so I'm really hoping I can use some KT77s or 88s in it to help with that problem, do you know if that bias mod will be able to get me in the range to use those tubes by any chance? What's the difference in voltage draw between 6L6s and KtT88s for example?

And that bias probe you posted costs way too much for me, I'm flat out broke, do you think this $25 one from eurotubes will work?
https://ssl.eurotubes.com/cart/index.php?page=view_products&category_id=108&sub_category_id=109

 

[Monsta-Tone]

You can always use a 50k cermet pot from Mouser. I use the 10k's because they are easily available where I'm at.
Weber has some 50k's too, but they have a bit of shaft that sticks out of the pot and I've had customers play with them and then tell me that the amp isn't biased properly or sounds like crap. :lol: Good thing I always mark them with a sharpie!


I have an old probe like the one that Eurotubes sells. They aren't bad, but they don't tell you what the plate voltage is.
If you're careful and use alligator clip leads, you could set up another meter to read the plate voltage, but don't reach in there for any reason while the amp is on.


For that matter, you could save the money and just get a set of KT's from Bob that would fit in the bias range of your amp. Just tell him what you're looking for and he can send you a nice hot set of KT's.