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  1. Word of warning: (not that anyone is paying attn) If your re-verb sounds re-pressed, make sure you didnt wire it backwards. Works much better now.
  2. I ended up going with the MOD 4AB3C1D. It was a little cheaper than the accutronics unit, and it had gotten good reviews. I had to replace its plastic mounting grommets with the rubber ones on the stock unit because the plastic ones are taller and the mounting screws wouldn't bite. It took me a few minutes to figure it out but after that it went back together pretty easily. As far as sound goes the reverb is pleasant, but subtle even with the reverb knob cranked. But it does make reverb so that's an improvement. Just wish I could turn it up to about 13. To fix the speaker cable I just cut the molded end off and replaced it with a 90 degree switchcraft plug. Looks good and works well. That plug was easier to install than any other replacement plug I've done. I'm a believer. I was pretty happy with all my testing on channel 1, but when I switched it over to ch2 it sounded terrible. The more I turned up the drive knob and hit a chord the more it sounded like sitting on a whoopee cushion. Is it time for a tube change? They have a lot of hours on them...maybe 200 or so. Does it matter that the clean sound pretty good but overdrive is weak and flabby? I did mod this amp a little bit back in 2011, and when I was all done it sounded pretty good, I thought. I suspect it just needs new bottles, so Ill try that first. It isn't my main rig anymore, and I thought of selling it but I just really like it so I wanna fix it.
  3. I messed up the speaker cable with the two crimp on connectors and the 1/4" plug. The stock model is lamp cord with a molded right angle plug. Does anyone know where to find one of these? I can only seem to find shielded instrument cable, which is difficult to put crimp connectors on. Thanks
  4. Wiggy, Thanks for the reply, I found the indicated thread. The spec reverb is Accutronics 4AB1C1B, which is a short decay model. It seems though that the long decay model 4AB3C1B is more common, so I may replace with that.
  5. I gutted the bc30 in an emergency to use it as a cab for a different head. When I took out the reverb I noticed that one of the magnet wires had broken and the spring isnt attached, so its fubar. Now I want to put the amp back together. Anyone have a suggestion on a replacement tank that would be an improvement?
  6. I assume youve taken all the screws out of the back panel and pulled it down at a 45 degree angle so that the back is open. To remove the chassis do the following 1) remove the mains power cable 2) remove the guitar cable from the input 3) remove the speaker cable from the output 4) remove the reverb RCA cables from the underside of the chassis 5) pry off the 4 plastic covers on top of the amp with a small flat blade screwdriver 6) remove the machine screws with a #2 phillips screwdriver 7) grab the HT and OT and gently pull out while lifting up then, 8) connect one lead of an alligator clip to the chassis, and the other end to the common of a multimeter. probe the power tube solder joints making sure to leave one hand in your pocket and confirm the meter reads 0V *if you arent sure about this step read back through this thread* 9) mod like hell...
  7. FYI Pictures of the MV mod on the Gain Stages thread.
  8. Thanks jefrs. ...you've got me wanting to crack it back open again...
  9. I switched out R5 and R6 for 470k. I was gonna put them on a switch but I couldnt figure out how to switch them both with the 1 DPDT I had available. It's hard to say how much it did for the tone...maybe needs some EQ tweaking now, but it definitely opened up the overdrive a bit. Before, I pretty much had the drive maxed out for most songs and now I have a little headroom, so I'd say it was a good change. Anybody know anything about a footswitch for this? --ML
  10. I finally did the MV mod. It works very well, except that when you turn the knob CCW it gets louder. I put the new knob on the back of the chassis next to the output jacks. Even with the volume tamed, I was having some problems with harshness still...I just felt like I couldnt get the EQ quite dialed in for the sound I was after. I decided to give the Marshall 20W mod a try. I went to the technician in the EE dept and asked him where I might find a couple 470k/1W resistors. He said "Whats this for?" and I said (and I dont really know what I'm talking about) "Cathode bypass resistor...to fix some harshness..."--trying to regurgitate what jefrs said about that mod--and he said, "Yeah 1M is pretty big right there. Try these 5751s and see if that dont fix it." GE 5751s in V1 and V2. That fixed it. Instead of screeching, it sings. I was blown away by the sound of this amp with the 5751s...when you max them out with the MV down you get this very musical overdrive thats absolutely creamy and beautiful. I'm still gonna give the Marshall 20W mod a try, and I'm gonna put the resistors on a toggle switch, but let me say that changing those 12ax7s to 5751s made a HUGE improvement. --ML
  11. Ok, I think I get it. By connecting the center lug and side lug, the total resistance across the pot changes as you turn the knob. One side of R39 is already connected to ground, so there is no need to ground the pot. It's been sitting for two days so it should be good to go...I'm gonna give it a try when I get home from work today. --ML BTW, I enjoyed your recordings. Your tone, and your band, sound great.
  12. Danny...thanks again for the reply. If you'll notice I fixed my earlier posts to make everything happy and visible. I had to drop by the office to use the server there, which I am supposed to be able to login to from home, but I cant. On that note...does anyone know where you can get some free server space to hold pictures and what not? Anyway, I'm thinking I can take a look at the schematic to find the resistor adjacent to the + side of the large caps and just clip that to ground to drain them...I'll be wearing thick gloves just in case. As far as the standby switch goes, I think I'm just gonna leave that where its at for the time being. The only issue I have left is wiring up the 1M pot. I was looking at it last night, and nearly as I can tell the center lug is common to the other two lugs, and it just divides the signal between them. I think what I will do is turn it all the way clockwise and connect the two that are shorted together where R39 was with a two conductor cable. Then I'll just fold over the other lug and solder it to the case and solder the shield to the case and solder the other end of the shield somewhere else, that way whatever signal is not being used just gets diverted to ground...or is that even necessary? Finally, should I leave R39 in there? B/C if you turn the MV pot all the way up and there used to be a resistor there what happens? So anyway I'm gonna drain the caps when I get home and wait on a response I guess. Thanks, --ML
  13. Well, I decided to give it a go. I stopped by Radio Shizzle and got a 1M Pot with a really long stem--guess I'll cut that later. As seen in the photo, it measured out at ~850 kΩ. Dont pay any attn. to that bottle of Dickel. So I put the Beastly30 up on the table and tried to take the back off of it. I never could get it completely out, but I got it out enough to fold it down. Next, I didnt know what to do. I went and got my winter gloves out of my drawer and put those on and tried to remove the power tubes. I decided I couldnt do that w/o breaking something so I just quit and went ahead and loosened the...amp...from the cab. After removing the amplifier I gently sat the transformers down on some notepads and snapped some photos. The reason I stopped here is twofold: 1) I dont know how to discharge the capacitors, and I dont know where to put leads to check voltage across them. If someone could look at this picture and explain that I'd be very grateful. 2) I'm not really sure how to proceed. First of all, once I unplug the spade terminals from the standby switch how do I reconnect everything? SS1 to PT1 and SS2 to PT2? Second of all...which leg of the 1M pot connects to what side of R39? See photos: Standby switch: Resistors: (R39 is dead center in the photo.) Being thoroughly perplexed and ever so slightly afraid, I just covered it up and left a nice note for the roomies. Any help would be well...imperative. Thanks.
  14. Thanks for the reply. Just before I get started with this, I've recorded something on the stock amp Class A, EQ ind., using an SM-58 1" from the grill off-axis and a stock Mexi-Strat, neck/middle pickup, volume 8, neck tone 6, bridge tone 3 The temperature in the room was 74º and the air conditioner was off. :) Never mind my playing, thats not whats being studied. Here is a pic of the panel: And the recording (volume is low) http://www.cae.tntech.edu/~mjlewis22/bc30mods/little_wing_bc30.mp3 Linear or audio taper? Shielded Cable? Which leg goes to what? Should I use the standby switch hole? What physical dimensions are needed to fit and accomodate a chicken head knob? Thanks again...as soon as I am able I will get some new tubes...and as soon as I figure this out some more I'll try to do the MV mod and take some pictures and what not.
  15. Hi all. I'm new to this forum, tube amps...I'm pretty much green all over. I recently acquired a BC30 as restitution for a bad purchase I made of a counterfeit Les Paul...and thats another story in and of itself. I was skeptical, I knew most of the things to look for, I called G.C.S. twice to authenticate the serial number and still got fooled. Anyway I explained what happened to the nice gentleman and he took the guitar back and gave me the amp and some other things to make it right. I was gonna just sell the amp but I couldnt resist the urge to plug it up and give it the old college try and...well I really like it. Overall, I think the tone is much better than my Peavey VK--of course this amp doesnt have nearly the gain that the VK does. My main axe is a Tele and I've discovered the brightness issues that most of this thread deals with. I normally play through Ch2, as I dont have a lot of use for clean stuff. (I play the alt-country/rockabilly D.B.T and Lucero style) As I understand it, and I dont really understand it at all, but I can read, doing the cap-mods sort of kills the overdrive, and if anything, I need more...oomph...as opposed to less. After multiple reads and extensive contemplation over this thread, I have the following questions: 1) What is the best way to "fatten up the sound" and at the same time add a little bit more overdrive? 2) Where can I get the parts needed to do the Master Volume mod? Is there a post-phase inverter MV mod for this amp? 3) Is there a manual for this amp? 4) For under $50--which tubes should I change? If someone would be willing to walk me through these mods a little bit I would photograph/document it for other users. Thanks in advance. I really like this amp and I have enjoyed reading this thread as I have already learned a great deal.
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