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mrw1960

BC 30 Tube Swap

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Greetings all,

I am considering swapping the stock tubes in my BC 30. I would like some

recommendations from anyone. As I have read from other BC 30 owners about the "Brightness" of the stock tubes, and mine is no exception. I want a real FAT tone. Since it was designed as a Blues amp,and that is basically what I play, I was thinking in lines for the power tubes maybe JAN Phillips 6L6WGB's, or Tung Sol 5881 re-issues. And using Tung Sol 12AX7's for the preamp tubes. And a Sovtek 5AR4 Rectifier. My next question. Are the POWER TUBES mentioned above the same height as the stock tubes? (I have not ever opened the back of my BC 30). Would I have to Re-Bias the amp? I wouldn't think so since they are the same types right? All input is welcome. Thanks

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No need for re-biasing. The 5881 RI bottles are shorter and do give it a warmer tone (I also went for 5881 and tungsol 12ax7 in my bc30) Have you clipped any caps yet? (I did several tests and settled on clipping c5 only) I also did a 'vasectomy' (tied a piece of string about an inch and a half from the center towards each side of each spring and then I tightened the string so as to squish the midlle portion of the springs) to the springs in the reverb tank to shorten the decay.

Very happy with the tone I'm getting now.

 

Cheers, amigo!

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Thanks Bro,

 

No I have not clipped any caps. I am a dweeb in regards to going in that direction. I would not even know how to do that. I have read other members doing the technique. I would have to see the schematics to be able to do that. How do I go about the "vascectomy"? I would be afraid that I would do something wrong and regret it. I think to be safe, I would start with the tube swap. I am no gigger, just a basement picker. I think that may suffice with me. thanks for the great tech advice. Anyone else have any input. I think the TUNG SOLS will make a huge difference. Thanks very much!!!

Regards,

Michael

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the brightness will change a little with the new tubes. the best increase in tone control performance and taming the brightness will come with at least snipping the caps.

 

When I started working on BC30 the stock phase inverter tube was just too "lopsided" so the power tubes could not work in unison. After trying another 12ax7 which didn't help too much I opted for a Groove Tubes special application tube which had been tested for balanced performance. That was the winner! I liked it so much I went with Groove Tubes for the replacing the rest of the tubes except for a brief segue into using the THD Yellowjackets with EL 84 tubes. Now I'm using the GT 6L6s and I'm very pleased with the tone. I do want to try the 5881s and the 6V6s but for now those will have to wait because I'm working on another project.

 

If you're looking for the schematic for a BC 30 I think you will find a link to it on this thread: http://forums.epiphone.com/default.aspx?g=posts&t=6812 I think it takes you to the ppwatt website.

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Getting the chasis out of the cab is simple. Disconnect everything. Unscrew and take off the back panel. On top of the amp you can see 2 black platic caps on each side... snap them off with a thin flat screwdriver or similar tool, you will now see the four screwheads that hold the chasis, screw them off patiently and don't be afraid of the whole thing dropping inside the cab... the chasis will eventually rest on top of the plywood reinforcements inside the cab. Now you can pickup the whole thing by sliding it from the rear. You can lay the chasis on a table without damaging the tubes, it will rest on the transformers on each side (just don't knock it around). You are now looking at the whole circuit board of your amp. Everything there is labeled. Check all the threads here for recommendations on cap and resistor mods. If you're gonna snip a cap, just snip one of its legs with a cable cutter, assemble the amp again and test. If you don't like it, repeat the procedure and solder the thing back. I for one do not regret having done it, the amp sounds so much better. Hope this is helpful in case you decide to go in there.

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So what cap should I clip, C5 or C6? Do I remove the cap entirely? Papamidnite said that he got better tone starting at C6. What is the difference with each cap?

Sorry for all the questions,Just want to do what is best. I checked the schematics and found the placements. Hep me Bro's!:-k

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