Mesa DC-3

Hi all, I am Dave, a brand new member here, but not a new Mesa owner. I have a few questions which may have been asked before, but I wonder if someone could please answer me in laymans terms, I am not good with electronics, after lots of time spent researching things, letters numbers and abbreviations of tubes etc tend to make me glaze over!!

I own a DC-3 Combo, I bought it used 10 years or so ago, and will never sell it. It has a tan leather(ette?) covering and a brown grill cloth, has anyone else got one this colour?

It is time for a revalve,i am doing all 10, do I need to use Mesa Branded valves , (it doesn't currently) and I understand it is fixed bias, should this determine my choice of valve? I do not wish to modify my amp in any way,apart from the valves.
I have read somewhere that I should use a spax7 (?) in the V1 position, thoughts?

The speaker is unbranded, but I do believe it is factory fitted, why is this? What speaker is it?

Finally, the amp is very noisy, especially when pedal are used straight into the input, is this normal? I suppose it could be due to the old valves thouh?

Many thanks in advance for help with any of my many question.

You can run any Mesa output tubes in the DC-3; however, because the DC-3 bias was set so high from the factory, even the Mesa output tubes run too warm.

I've had good luck with The Tube Depot and would recommend them although there are other excellent online vendors. I'm sure the Tube Depot has some "cold" EL84 tubes that they can sell you. Tell them the amp you have and that you'd like tubes colder than any Mesa tube.

I found that my DC-3 sounded better with a warm bias as opposed to a scorching hot bias.

talltxguy said:

You can run any Mesa output tubes in the DC-3; however, because the DC-3 bias was set so high from the factory, even the Mesa output tubes run too warm.

I've had good luck with The Tube Depot and would recommend them although there are other excellent online vendors. I'm sure the Tube Depot has some "cold" EL84 tubes that they can sell you. Tell them the amp you have and that you'd like tubes colder than any Mesa tube.

I found that my DC-3 sounded better with a warm bias as opposed to a scorching hot bias.

Click to expand...

I completely agree here. It is a very simple process to change out the bias resistor for a colder bias. This will prolong the life of the tubes, and your amp by reducing a lot of heat. It will still get a little warm, but you won't be able to fry eggs on it any longer. A 100K resistor brings the -bias supply down from -11v to around -14 (I got -19.5 with a 95K resistor, my DC3 from May 1994 sounds great, and runs super cool). Can also now run the Reissue Mullard EL84s which sound fantastic. Before, on the hot bias, any quad of Mullards I tried to run red-plated. JJs were fine.

There are not many current production EL84s that can hold up long in a DC3. They are just biased way to hot.

The noise you are experiencing could be from a # of sources. Replacing the tubes should help. Make sure you are using a good shielded guitar cable. TVs will cause noise, as will other electronic devices that emit radiation.

Just based on all the readings I've done, I'm wanting to put a 100K R in place of the piggy backed 120K + 470K resistors that are in thre now. Just to see if it runs a slight bit cooler. It's the only R in the amp that is already modded, so I assume I'm replacing the correct one. I have a 100K 1/2 watt 5% which I believe will run ok.

I want to see if it will stop the EL84M from redplating, I had 4 in there, one of them redplated no matter which socket I put it in, so that tube will probably go, but I want to see if the reduced R value will make any difference.

I'm wondering if a similar mod can be done in the Subway Rocket 44.

soundchaser59 said:

Just based on all the readings I've done, I'm wanting to put a 100K R in place of the piggy backed 120K + 470K resistors that are in thre now. Just to see if it runs a slight bit cooler. It's the only R in the amp that is already modded, so I assume I'm replacing the correct one. I have a 100K 1/2 watt 5% which I believe will run ok.

I want to see if it will stop the EL84M from redplating, I had 4 in there, one of them redplated no matter which socket I put it in, so that tube will probably go, but I want to see if the reduced R value will make any difference.

I'm wondering if a similar mod can be done in the Subway Rocket 44.

Click to expand...

I did that a long time ago and never looked back. Found some good 5% tolerance ones, and put the lowest testing one in there. Around 96K or so.