how to change tubes in my boogie

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can you just replace the tubes or do i need to take it in and have it done the volume is going up and down and there is a loss of gain after it is on for about 15 minutes does that sound like a tube problem

[Infernal Death]

Re: how to change tubes in my boogie

What Mesa do you have ? I don't know if that's the case with all Mesas but my Dual Rectifier has fixed bias settings so you can't use any type of tubes with it (that's of course only true for power tubes).
With this fixed bias setting you simply can do only three things:
1. Buying original mesa tubes as they are matched to work with the bias setting.
2. Modifiy your Mesa with a bias pot so you can change the bias setting and make it work with other tubes.
3. Ordering your tubes from a good tube shop who are able to match your tubes for your mesa. I just ordered some new tubes and they will select the power tubes so i can simply put them in my rectifier.
I think this is the best option as mesa tubes are expensive and i don't like modifying a working amp.

Of course if your mesa doesn't have fixed bias settings forget my post [img]/images/graemlins/wink.gif[/img]

Flo

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Re: how to change tubes in my boogie

its a subway rocket would surging volume and loss of gain possably be a tube problem

[parntz145]

Re: how to change tubes in my boogie

Your tubes are problaby not rated correctly. When I had my Mesa rack gear I used all JJ tubes. I called Bob at www.eurotubes.com He was able to send me tubes that were rated the same as the Boogie tubes that were in it. It is a fixed bias but the new tubes must be within the rating of the ones that were already in there. I think your tubes are the problem in this case. Try a different set that are within the biasing range of your old ones. That is why Mesa uses the color coding on tubes. Dont buy Mesa tubes they are to expensive and imo they suck. Try another brand of your liking.

[Shawn Lutz]

Re: how to change tubes in my boogie

the Rocket has EL-84's I believe, 4 of them. Good news is those are not expensive to change (price out a quartet of 6550 [img]/images/graemlins/smile.gif[/img] You can get them from Mesa but you don't have to, as mentioned you can call eurotube or tubestore.com and they'll match what is marked on your tubes you have in there right now.

It sounds like a power tube problem, swap them out - should do trick

[Twisteramps]

Re: how to change tubes in my boogie

before you swap the power tubes... if the amp has an fx loop, just put a spare guitar cable in there. Plug one end to the send, one end to the return. If this fixes your problem, then you have a dirty or damaged jack in the fx loop - take it to a tech or just keep a cord in there.

Pete

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Re: how to change tubes in my boogie

cool thanks for the info

[bluebullet]

Re: how to change tubes in my boogie

i think pete might have nailed it. the effects loop has a mix control i turned the loop off and played for 2 hours and no problems

[Lurchhammer]

Re: how to change tubes in my boogie

When you change preamp tubes in a Dual Rectifier Tremoverb, is there certain valve locations where specific tubes should be used? I know that the V1 is the most critical and I've heard that a 'hotter' 12AX7 is better for high distortion (I'm using an Electro-Harmonix 12AX7EH there) but does the V3 or other locations benefit from a specific type?

Thanks for any info,
Lurch.

[Infernal Death]

Re: how to change tubes in my boogie

As i just replaced all tubes in my dual rectifier i think i can say something about this. V1 should be low noise as it's the first stage and critical to noise. The only other tube i used a special one is the last one, the phase splitter. I bought a "balanced" version from the tube store where i order my tubes. This means that both circuits inside the tube are as close as possible so you have the same for both halfs of the phase.
The shop where i bought the tubes offers the chinese 12AX7 i bought as a normal Version, a V1 Version and a balanced Version. It's a german store but i guess the big tube stores in america offer the same.
I didn't use any hotter preamp tubes for the gain stages as i also use a Boss MT-2 in front of the amp.

Hope this helps

Flo