I bought an Earth Sound Research B-2000 bass head and matching cab yesterday for $150 (and matching serial numbers). A friend who's moving across country needed some cash quick, so he sold it to me. He said he hadn't played in awhile and couldn't guarantee it would work, but he knew it needed a new fuse and possibly a new power tube.

Disclaimer: I only know the very basics when it comes to tube amps, and near squat about bass amps.

Bought a fuse today, threw it in, and it turned on! But here's the problem: It has a loud, continuous humming buzz like if I had a cable plugged into an input channel but the other end was just laying on the floor. If I play through it, I can hear the guitar but it meets a lot of interference because of the loud buzzing. Any ideas of what this could be from? The friend who sold it to me said it could be a bad solder connection and to pop off the back and take a look around or an indication that I need a new preamp.

To test and make sure that the problem was in the head and not the cab, I plugged my Mesa Dual Rec into the cab and that all worked fine. However, I noticed that the sound was only coming from the top speaker and not the bottom. If you look at this picture (the top one should say "Super") you'll notice that there are two separate inputs for the head so I'm wondering if each cone works independently or if I just have a broken bottom speaker? Or does it have to do with the head and cab combo? I made sure the ohms were correct but I guess it could be any number of things.

http://i157.photobucket.com/albums/...pics/Ampcab.jpg
http://i157.photobucket.com/albums/...orpics/Text.jpg

Thanks, all help is appreciated!

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oh man you've got alot going on. Congrats on the Earth Soundd find though! Theyre pimp once you get them workin.

anyways, loud hum or buzz sounds like either tube problem, grounding problem, or POSSIBLY electrolytics. I suggest replacing both tubes and the electrolytic caps, and then check to see if theres any loose wires.

Now, if theres no sound from the bottom, speaker is either blown, or disconnected. Open er up and check for connections. If all is connected, might be blown

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I haven't checked out the wiring yet, but before I do anything I'm going to make sure theres no bad connections.

What is a grounding problem and how can it be fixed? What are electrolytics? Is there a way simply by looking at the tubes to see what is blown?

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i think a ground issue is when the ground wire needs a fixin' (ie it came off and needs to be re attached.)

for a "bad tube" issue you can get things that hook into a multimeter or a device on its own that tube guys make, that reads a tube once you plug into it, and it tells you if its good or not. best thing to do is replace every tube. its not alot at all. I just re-tubed my peavey XXX and it cost me less then 200 bucks (should have been less, but thats a long story. i got fucked by the tube store but a local guy who does tube work gave me a little hook up).

ebay store's are cheap and im sure some american guys can give you good links to US tube dealers.

as for electrolytics, i THINK its a capacitor. I learned about them back in grade 10 but like HELL if im right

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grounding problem, basically a bunch of shit in your amp will be soldered to a plate, which will be soldered to the 3rd prong on the power cable. If theres no plate, then its all typically just soldered directly to the 3rd prong. Theres a problem if some wires are disconnected from the ground.

electrolytics are capacitors yes. They have fluid in them to make them function, which usually dries out after a number of years, rendering your amp useless. In some worst-case scenarios it can damage other components, but typically the fuses are in place to cover your ass in a situation like that. Anyways, get yourself a schematic of your amp if possible, and the capacitors on the schem with + signs next to them are electro... and the + sign tells you which side of it is polarized so when you get them you can put them in THE RIGHT WAY and not the wrong way hahah. An easier way to do this is to take it to a tech :P

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How much are these tube multimeters?

If I get to a point were I can't do it myself, I plan on taking it to a tech or just re-sell it.

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just a regular multimeter from home depot will do ya

theyre like 30$
http://www.homedepot.com/webapp/wcs...dkey=THDSiteMap

you could also get a weber bias rite (specifically for power tubes), but theyre 120$
https://taweber.powweb.com/biasrite/br_page.htm

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