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Thanks PapaMidnight, thats put me straight. It says 471 on one line, 1kV on the next and sec on the third. Dont know what sec means. Though I have read that the 1 in 471 is a multiplier, that confused me a bit, originaly i was looking for a 471pf cap!! LOL


I would have simply moved C3 to C10, but it looked far too fiddly. Ive found some on rapidonline.com anyway and they're based in England, £0.06 each and £5.00 postage!! better order a few bits n bobs to get my moneys worth i think.


BTW what is some-timers disease?

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<a href="http://s85.photobucket.com/albums/k75/Knuckledraggerz/?action=view&current=Picture029.jpg" target="_blank"><img src="http://i85.photobucket.com/albums/k75/Knuckledraggerz/th_Picture029.jpg" border="0" alt="R21 Resistor ." ></a>

<a href="http://s85.photobucket.com/albums/k75/Knuckledraggerz/?action=view&current=Picture028.jpg" target="_blank"><img src="http://i85.photobucket.com/albums/k75/Knuckledraggerz/th_Picture028.jpg" border="0" alt="Photobucket" ></a>

<a href="http://s85.photobucket.com/albums/k75/Knuckledraggerz/?action=view&current=Picture027.jpg" target="_blank"><img src="http://i85.photobucket.com/albums/k75/Knuckledraggerz/th_Picture027.jpg" border="0" alt="C3" ></a>

<a href="http://s85.photobucket.com/albums/k75/Knuckledraggerz/?action=view&current=Picture026.jpg" target="_blank"><img src="http://i85.photobucket.com/albums/k75/Knuckledraggerz/th_Picture026.jpg" border="0" alt="R15" ></a>

<a href="http://s85.photobucket.com/albums/k75/Knuckledraggerz/?action=view&current=Picture025.jpg" target="_blank"><img src="http://i85.photobucket.com/albums/k75/Knuckledraggerz/th_Picture025.jpg" border="0" alt="C5, C6" ></a>

<a href="http://s85.photobucket.com/albums/k75/Knuckledraggerz/?action=view&current=1120.gif" target="_blank"><img src="http://i85.photobucket.com/albums/k75/Knuckledraggerz/th_1120.gif" border="0" alt="Cooder" ></a>

</center> I hope these Pics come out .Let me know If not go to this site. I tried to Photo the board with mods

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Latest update C3,C5,C6,Caps clipped C15 changed from 22uf 35w to 2.2uf 35w ,R15 Resistor from 2.2k 1 Watt to 1.5k 1 w, R21 from 2.2k 1 w to 1k 1w these mods really open this amp up ,The drive using tung-sol 5881's very usable and the break up on clean, exactly what a blues amp is supposed to do .The one thing I now notice is the EQ is way more definable between active and not ,Also get more use out of the mid channel. Whats nice is that you set EQ and then roll off Guitar tone and Volume is huge .I've tested with both a Tele single coil and a Hollow Body with Phat Cat P90's . I just played Slide on the Tele and I could go from Johnny Winter to Ry Cooder with a quick roll off of the tone control ,Test it out for yourself

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Hi guys, just about caught up with these mods. Before doing any more I decided to read up a little about electronics and I found this page on carbon resistors http://www.geofex.com/tubeampfaq/TUBEFAQ.htm#CarbonComps , so there may still be some more sweetness to inject yet! (this site has LOTS of mod ideas!!!)


Also this page helped me get to grips with what the bright cap mods actually do http://www.diystompboxes.com/pedals/tubedummy.html


I havent changed C15 yet 'cause I'm pretty sure I'll have to remove the PCB to get to the solder, Papa, you've done this already, is there anything I should be aware of before attempting this? or should I just get stuck in and be carefull? Actually, does anyone know how to remove a cap like this (cylinder damn close to the PCB) WITHOUT removing the PCB?


Cheers and happy modding!


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It's been awhile since I frequented this forum, nice to see some activity on the BC30.


I bought my BC30 in 2005, used it as a practice amp for a few months, and then bought a Genz Benz Black Pearl, which has been getting most of my time when it comes to clean playing.


I am still lacking a satisfactory 6L6 amp, so I'm thinking of dusting off the BC30 and investing some bucks in it. Mercury Magnetics is selling a replacement OT and choke for the BC30 for $230, which would not be unreasonable, and it could also use a change of speakers. The Red Fangs in my Black Pearl are excellent, but I'm open to any suggestions for Eminence speakers that will work with the BC30.


New OT, choke, speakers, Tung Sol 5881 reissues, combined with the the cap cuts suggested might do the trick.


Papa Midnite, have you considered the choke kit MM is selling for $30? I have no idea how to install one, so any insight would be appreciated.

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I have finally completed all the mods on my BC30 as follows: C3,C5,C6 removed, R15 - 1.6K, R21- 1.1K and finally C15 reduced from 22uf to 2.2uf. The things now sounds great. EQ is extremely effective and sensitive. Sounds very different to when I got it, has more gain but it is by no means a 'high gain' amp. Bigger sound and more responsive to touch. I am finished now and don't intend to tinker anymore but you never know.............

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If you think this amp is too bright sounding try this mod .Open er up find C6 cap and cut .Pull it back slightly. Now fire it up and listen to the difference.If that is not enough Cut C5 [.This was enough for me ].Again not enough C10 [.have not gone here yet .] The brightness is gone the EQ way more tweak-able .I am Jumping between Tung-sol 5881's and a THD yellow jacket with el84's that's right 84's with these this amp cooks .Also Weber speaker diffusers and for God sake put it on an amp stand .This is a jaw dropping experience .This is how this amp is supposed to sound


Does this mod affect the overdrive channel, the clean, or both?

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I have always found the overdrive channel to be excessively bright and the clean to be dull and lacking any clarity.


If I cut the caps, as per your post, would it make the clean even darker? I certainly wouldn't want to do that.


Basically, the one things that drives me nuts about this amp is that if the EQ is dialed in nicely for one channel, it sucks for the other--making it useless as one amp on stage for gigs.


Any thoughts?

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'Would it be wise to discharge the electrolytic caps. before doing any soldering? '

YES! I do it by unplugging the amp from the mains but leaving it 'on' and in 'play' mode overnight, I hope this is a safe way, I'm still alive...


Thanks for the C15 advice Dave, I'll print that out for future reference, cheers, though having done the other mods im actually pretty happy with where it is now, and also I havent figured out why my reverb keeps cutting out. If its an invisible crack in the PCB then messing with it may only make it worse. :P


So far I've noticed that Channel2 is still brighter than Channel1, wouldn't reducing C15 from 22uF to 2.2uF take more bass out and make this problem even worse? It seems like a big (and possibly risky) job which might not be worth it.


What I might be willing to do is put a cap in parallel with the plate resistor to tame some of the highs on Channel2, thats where the schematic gets too complicated for me, is R20 or R48 the plate resistor? (or both!? or neither?) anyone? Actually if C30 and C31 are trebble roll of caps then I could change both their values to brighten the clean channel AND tame the overdrive, I really wish I knew what I was talking about! LOL Electronics course here I come!

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'Would it be wise to discharge the electrolytic caps. before doing any soldering? '

YES! I do it by unplugging the amp from the mains but leaving it 'on' and in 'play' mode overnight' date=' I hope this is a safe way, I'm still alive...![/quote']


I had read that what you are doing is not a safe way:



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  • 1 month later...

Hello everybody - I am new here and looks like I have come to the right place. I just bought a BC30 and am very pleased with it overall. It is a bit too bright, though and I am thinking about the cap mods you all have talked about. I handwire Fender blackface reissue amps to original specs for people but really know nothing about the internals of this amp. The cap mod seems to be the way to go. Anything else about the mods? Any drawbacks? Your help would be appreciated.

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  • 3 weeks later...

Here's my updates on improving my BC30:

1) No circuit mods yet as described earlier in this thread.

2) Changed some tubes as follows (I had to order GT through a catalogue - Woodwind & Brasswind -GT Gold tubes are currently 20% off) While waiting for the GTs I nabbed some Ruby/JJ 12ax7 for the signal gain and a 12at7 for the phase inverter position. Wow!

3) Found a Fender 4x12 on the local Craigslist cheap (pardon the gloat - $90) It had a driver with an open coil. I figured it would be loaded with the regular Fender fare but found all drivers were Celestion G12-65 15 Ohm.


The tube change for the phase inverter position to a 12at7 really smoothed out that lame distortion and gave me a little less headroom on the clean channel with a much smoother breakup as I drove it harder. The Ruby/JJ 12ax7s gave me "softer" tone with less treble. I'm hoping that when the GTs arrive that the tone will improve further. Those will be matched 6L6s (with the low output rating) along with the SAG-at7-MPI for the phase inverter (the current 12at7 will get moved to the reverb drive position) and a couple of the 12ax7-C (from China) to experiment with in the signal positions.


The Celestions were somewhat of a surprise. They sounded pretty much just like the stock Lady Luck drivers in the BC30 with 2 notable differences...they broke up earlier and they had more bottom end than the Lady Lucks. I'm still trying to sort out if these differences are due to the Lady Lucks being newer and still needing to be fully broken in (the Celestions are already well broken in) and then the extended bottom being due to the 4x12 cabinet. I figure I'll wait a while (a month or so) before I start swapping out drivers to the give the Lady Lucks some more time on the break-in process.


After the GTs arrive and I get them installed and see how they play I'll decide whether or not to mod the circuit.


I'm likin' this more all the time!

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HOLY Flurkin' SCHNIT! Oops! Can I say that here?!? Oh well... I already did.


Yesterday the Groove Tubes came so I knew I would be spending this a.m. working on the amp. Here's how it went down...

1) I pulled the original Sovtek 6L6 tubes and replaced them with a matched duet of GT 6L6 tubes that were rated 3 (blue) which is low rating. I selected this rating in the hope that I would get an earlier breakup and I did.


2) I pulled the phase inverter tube (the 12at7 I swapped for last time) with a GT SAP-AT7-MPI (a 12at7 with matched output on each half of the tube). I did this with the idea that each 6L6 would receive an equivalent signal level so the overdrive/distortion of the drive channel wouldn't be so "jagged" sounding. The first 12at7 I put in there cleared up a great deal of the roughness of the drive channel but it was still "jagged" but much improved over the original EH 12ax7 that was in there.


3) I didn't put the back on, just turned it around and plugged it in to see if there would be any difference. WOW! HFS! What a difference! I could tell I was getting my full 15/30 watts worth! I also got the all the brightness that others have spoke of. The decision was made to snip the C3, C5, & C6 caps. Before I decided to do the surgery I thought I would give the Celestions another spin. A clear difference over the Lady Lucks and a difference I regard as an improvement. I figured that I'm this far along and the decision to snip the caps had already been made so I decided to go ahead and change the speakers. While I was at it I figured that I would go ahead and take that 12at7 that I pulled from the PI position and pt it into the reverb drive position.


4) I got it all done and just finished playing with it...INCREDIBLE! This thing now barks with authority! It's very touch sensitive now and not nearly so bright.. I can actually use my treble controls not only on the amp but on my guitars also. The Celestions sound even better in the semi-open back BC30 cab than they did in 4x12 cabinet. The clean channel now has a killer tone and incredibly smooth break-up when you get on it. The drive channel is now very usable with plenty of bark and a smoother growl rather than that "jagged" sounding distortion. Oh yeah! This baby's a keeper now!


A big thanks to Papa Midnite, cgil, stevencg2, sprinter and everyone else who contributed to this thread!


As an added note, there's a place that's new to me called Warehouse Guitar Speakers (WGS) that are offering what's billed as a replacement for the Celestion G12-65 speaker at a reasonable price ($65), here's a link: http://www.warehousespeakers.com/

Here's another placed that offers some interesting alternatives...Weber Speakers: https://taweber.powweb.com/weber/

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Hi all,


has anyone of you recorded some samples to compare the tone changes before and after the mods ?


I am quite interested in doing a few mods to dampen this 'brightness', but before cutting out caps and resistors in my brand-new BC30, I'd like to listen to the (expected) improvements. In other words: I really wonder what these mods really do...


could anyone help me ?





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