DC-3 bias

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BobR

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Hi everyone. New DC-3 owner here....with a slight redplating problem. The amp has white label Mesa EL-84's in it. Wouldnt have noticed it if the room wasnt fairly dark. Ive read this particular model runs the tubes hot. Im wondering if a lower current draw set is the answer or if I have a bias supply issue with the amp. Wish I hasd a 9 pin probe! Bob
 
This is what I've been told^^Mine is quite finnicky.Tried several Mesa sets,ended up with JJ's from eurotubes.Tell them what amp you have and they'll set you up.They are JJ only tho.Another good one is Dougstubes.A few brands to choose from,again specify the amp.Or get ahold of Mesa,they'll tell you what you need.
 
bhsbhswarp said:
This is what I've been told^^Mine is quite finnicky.Tried several Mesa sets,ended up with JJ's from eurotubes.Tell them what amp you have and they'll set you up.They are JJ only tho.Another good one is Dougstubes.A few brands to choose from,again specify the amp.Or get ahold of Mesa,they'll tell you what you need.


Did yours slightly redplate with the Mesa's? Bob
 
Ive installed a 12vdc fan in mine and ordered the lowest current drawing JJ tubes I could from Doug's Tubes.

This amp is designed to run TOO hot. With a -11 bias voltage and close to 400volts on the plates its bound to run almost any tube over 70% and some probably at 150% . Its crazy. I havent been able to figure out how to mod the bias yet. Hopefully the coolest tubes will work.

As far as tone goes its easy to dial in great rock and roll tones. Some mesa's require a bit more patience-not this amp. Its simple and Im really digging the tones! Bob
 
hey Bob,
contact http://www.mansfieldguitars.com
they have a bias kit for your amp.I will be modding mine in the near future also.You could also pull the 33k resistor and install a 50k pot and make it ajustable bias.One weird thing I've noticed on my DC3 is if I run the output control below 2,2 1/2 it gets hot quik.If I keep the output up and turn it down with the channel master I have no problems,like I say" weird " to say the least. :shock: and yeah the tonez these amps put out is awesome.
 
The bias is weird on the DC-3. I tried installing a 25k pot and a 50k pot. It didn't seem to help at all. I tried this on 3 different DC-3's.
I think it has to do with the Phase Inverter circuit too, but since I don't have a 3 anymore, I can't really experiment.

It would be interesting to see what is in the Mansfield mod kit.

I ended up getting a set of EL's from Eurotubes and installing a 120 volt fan from a Mark IV in my last DC-3 combo.
 
I've done the fx loop mod, the volume mod.Now if someone could come up with a bias mod for this Dam thing,that would be great.Why in the hell would you run this at -11volts with the goofy phase inverter.It's makes a good amp,well,not so good amp now does'nt it.WTF!!The easy bake oven known as the DC3.
 
This info below is from the Mesa Boogie website. Please don't be fooled by the so called 'experts' giving you their crap opinions on how to bias your Boogie. I'm a Mesa user since 1981.

READ BELOW:

"So the end of the short answer is this: Since a bias supply needs to put out the right voltage and never vary, I wanted to build amplifiers that were individually hard wired to the correct values and NEVER needed adjustment. And for 25 years, that's how Mesa/Boogies have been built.

Time to change tubes? Just plug our tubes into any one of our amps and you're DONE. No tech needed. NO bills and no BS about biasing. And most important: The bias is RIGHT because it can't change!"
 
LAdude said:
This info below is from the Mesa Boogie website. Please don't be fooled by the so called 'experts' giving you their crap opinions on how to bias your Boogie. I'm a Mesa user since 1981.

READ BELOW:

"So the end of the short answer is this: Since a bias supply needs to put out the right voltage and never vary, I wanted to build amplifiers that were individually hard wired to the correct values and NEVER needed adjustment. And for 25 years, that's how Mesa/Boogies have been built.

Time to change tubes? Just plug our tubes into any one of our amps and you're DONE. No tech needed. NO bills and no BS about biasing. And most important: The bias is RIGHT because it can't change!"


You joined the BB today just for this? :shock:

Hate to break it to you but some of these experts here really are experts, more expert than a guy could ever be just being a "user." Why is your p.o.v. not crap? I might be able to figure out what "message" you are trying to convey here, but I won't understand the attitude that makes a guy barge in here and start his first post spittin' and whackin'.....
 
LAdude said:
This info below is from the Mesa Boogie website. Please don't be fooled by the so called 'experts' giving you their crap opinions on how to bias your Boogie. I'm a Mesa user since 1981.

READ BELOW:

"So the end of the short answer is this: Since a bias supply needs to put out the right voltage and never vary, I wanted to build amplifiers that were individually hard wired to the correct values and NEVER needed adjustment. And for 25 years, that's how Mesa/Boogies have been built.

Time to change tubes? Just plug our tubes into any one of our amps and you're DONE. No tech needed. NO bills and no BS about biasing. And most important: The bias is RIGHT because it can't change!"

Just joined for that? Many would call this trolling. You have apparently never owned a DC3 and watch it eat power tube after power tube. Fried an egg sammich on the top during a set break.

Before you go off spouting at the mouth, you should do some research, and consider your responses before you alienate everyone on the board that could be here to help you later on.
 
I want to agree with you in the jjs but I can't. I had a set of matched JJ rebranded Ruby..... BS....... that amp ate them up.

Have a matched quartet of plain old Russian sovteks. They are holding up fine. They are finniky little amps that sound killer mine is bass heavy. So I turn the bass .down
 
I don't own a DC-3, but I'd like to share my experience with my Studio 22+.

I was doing mainly very small gigs (cafe size) and wished I could get the amp above one and a half on the master volume. I had some work done on it, including a bias adjust kit.

Frankly, I wish I'd never touched it. It's gone from a little marvel that could keep up with amps 3 times its output, to having to be slaved through a separate power amp for anything BIGGER than a cafe. Its a case of don't wish too hard, you just might get it!

Just my 2 cents worth, I get excellent advice from this forum, and appreciate it. However, I don't think changing out your EL84s every year or so is a big price to pay for a huge sound. If you're blowing them earlier than that, it's not a bias issue, that's a fault.
 
When I had an adjustable bias put on my DC-3, I found that the loudness of the amp was very directly related to how hot the tubes were running. When I got the bias down near the 80% range, I had a bit more play with the master volume.
 
tonedragon said:
I want to agree with you in the jjs but I can't. I had a set of matched JJ rebranded Ruby..... BS....... that amp ate them up.

Have a matched quartet of plain old Russian sovteks. They are holding up fine. They are finniky little amps that sound killer mine is bass heavy. So I turn the bass .down

Were those tubes labeled JJ or Ruby? How did you know they were JJs? Most Ruby tubes have a Ruby label and can be difficult to tell what manufacturer the tube actually is. I has a Set of 6L6 Ruby's that were supposed to be Sylvania. Turned out they were Sino, and didn't last longer than 6 months. I try and stay as far away from Ruby as I can.

Ruby EL84s are re-branded Sovteks, JJs, or whatever they can get their hands on in big lots cheap. Then they test out the bad/weak ones, and pair them up/sell them in lots to other distributors/retailers. Ruby is another Groove Tubes. Except I think GT puts more effort into weeding out bad tubes.

The Retail tubes that JJs sells are solid reliable tubes with good tone. I have never had any issues with them. Some days, my amp is on all day long when recording. Current set has been in for a year. Still noise free and sound great. JJ is pretty good about JJ branded tubes being in good nick. The rest they sell off in lots (Ruby, Groove Tubes, etc.).
 

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