Guitslinger1281734018
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Posts posted by Guitslinger1281734018
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Guitslinger et al' date='
I found that it is possible to exchange caps and resistors from the top of the board if you [i']can[/i] flow a little tin/lead solder down the new component legs, the capillary action flows it onto the board, but beware the original solder can explode away from the legs, fortunately the two types are mixable.
Regarding C15
Cathode decoupling caps are chosen to give to give a bottom roll off frequency to the valve section. A large cap value will give a lower frequency than a smaller one. I have seen values of 220µF used to get 1Hz through whereas 22µF would only pass 10Hz. [ref ISBN 978-0-7506-5694-8]
Thanks for the info on C15, which makes sense, larger cap values create more bass frequencies, and in that case, I'm glad I chose not to change it.
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Good stuff guitslinger! So' date=' how's channel 2 sounding?
I'm quite happy with how channel 1 sounds on my amp. I now would like to do something about channel2. The drive is just "harsh" is the best way I can describe it. It's much better than it used to be but it still needs to be tamed. I'll give the 5881s a try as your description sounds intriguing.[/quote']
Harshness is typical of most tube amps that are in need of new tubes no matter what the cost or design of the amp, so the first step in dealing with harshness is having a set of spare tubes waiting.
I played all of the channels for awhile tonight, and even though harshness can be introduced by turning the treble control up too much, I can't say the amp sounds harsh at all given some reasonable tone tweaks. The good thing is I no longer have to turn any of the tone controls to an extreme to get acceptable tones, the bad thing is the channels are voiced quite differently and require adjustments to the tone controls when changing channels. The clean channel requires turning the treble up to around 7 and the bass down to 4, while the drive channel is the inverse being brighter, the treble was set at 4 and the bass at 7, more or less. The mid control can introduce harshness with any amp, so it must be used judiciously.
I will agree the drive channel is a little thin sounding, but adding bass compensates adequately to get useful sounds, but it would be nice to fatten the overall sound of the amp. One option is speakers, and another is a different output transformer, but I'm not sure I'm willing to invest a lot more in my BC30. As is, it makes a good backup amp.
I should also add that my tests were conducted at bedroom volume levels: I'm sure that cranking the volume on my BC30 would fatten and improve the overall sound, as is the case with most tube amps.
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Last night I experimented some more. I diverted the output of the BC30 into a pair of 16ohm Eminence Red fang speakers, and the sound was very good, with pronounced low end, but still somewhat on the dark side, meaning the clean channel.
Next I swapped out the stock power tubes with a set of Tung-sol 5881 reissues, and the difference was dramatic, it was like lifting a blanket off the amp. Now it has Tung-sol reissue power and preamp tubes, and a JJ rectifier tube. Through the red fangs the top end was sweet and the low end well-defined, but I don't think the red fangs are the exact match I'm looking for, and note that most amps will sound decent through $350 worth of speakers. What the BC30 needs are some good American sounding speakers, the red fang has an over the top British tone.
I hooked the Lady luck speakers back up and the sound is good, the clean channel is not as dark as it was, so it may be alright as is. The next choice is a better set of speakers, but I may change out C15 if I can find the right cap, but I'd still like to know what what the change brings.
EDIT:
I played on the BC30 some this morning and I'm impressed with the way it sounds as is. With the treble at 7, the mid at 5, and the bass set at 4, the clean channel sounds beautiful. The change in tubes fixed the extreme darkness in the clean channel.
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I finally got around to modding my BC30 last night. I cut C3, C5, and C6, and also changed out R15 and R21. What I was lacking was the electrolytic cap needed to change C15, and also realized the board will have be removed to replace it, so I skipped C15, but I would like to know what effect dropping the value from 22uF to 2.2uF has.
The results are largely positive, the amp sounds looser, with a little more sag it seems, and fuller. The drive and interactive channels are vastly improved, offering a lot of tonal variations, and the tone stack functions within the normal ranges with those channels. I was getting some low end thump from the interactive channel that was very impressive.
The issue is with the clean channel, which is quite dark compared to the drive channel. I'm having to turn the treble up to 9 and the bass down two 2 to add any bite to the tone. The tone is also fuller like the other channels, but I'd like to figure out a tweak to balance the clean channel out. As is, it will be impossible to switch between channels without adjusting the tone controls. I wonder if I could reconnect one of the caps using a lower value and achieve my goal--anyone have an idea on how to?
As of now there are stock power tubes and speakers in my BC30, with Tung-sol reissue preamp tubes. I bought a set of Tung-sol reissue 5881 tubes to go in it, and I may try it with the Red Fang speakers in my Black Pearl. The sound of the wound strings through the Lady Lucks is pretty good, but the top end sounds flat to me, so new speakers are a definite must.
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I had a Gibson rep send me latest schematic day before yesterday and it's the same as the one I had, dated August 2006. If there were any changes made it was in the first year of production, 2005.
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My improvement looks like:
- C5 is jumper wire - yes that is a direct connection to the first two degrees of amplifications
What does C5 jumper to?
I've been holding out on modding my BC30 which is 2005 model, and now that it's clear there are differences in the older and newer models I'm a little confused as to what to do. It might be a mistake to incorporate 2009 specs to a 2005 model without going over both schematics closely.
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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.
Blues Custom Mods
in Epiphone Amps & Accessories
Posted
More thoughts on the BC30.
All of my experiments conducted over the weekend were done with the back off, and it occurred to me that with the back off much of the fullness and bass frequencies that happen with a closed back combo were being lost. I put the back on and tested all three of the channels tonight, and went away feeling good about the BC30.
The clean channel sounds good with no extreme settings to the eq section: plenty of bass, plenty of clarity, with no harshness. Switching from the clean channel to interactive mode sounds good, plenty of good overdriven sounds there. What I'm learning is that even with the changes made to the circuitry, the tone controls still act differently than one would expect--there are a lot of hidden tones in the BC30 that can be coaxed out by twisting the eq knobs every which way.
The issues with the drive channel being overly bright remained until I cranked the mid control (not to be confused with the middle control) a generous amount, which adds fullness and brings it in line with the clean and interactive modes. I've concluded that an investment of $150 in speakers will be a good one, so that's next. As mine is now, I rate the BC30 a 7.5 on a scale of 1-10. A good set of speakers could push it up to an 8 or higher. I'll report back when the speakers are installed and tested.