Tweaking the Bugera V5 Circuit

Discussion in 'Shock Brother's DIY Amps' started by tele_wah_fuzz, Jan 19, 2014.

  1. tele_wah_fuzz

    tele_wah_fuzz Tele-Meister

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    I bought a Bugera V5 last week. Playing through an eq pedal I was getting some really good sounds out of it. However, by itself, it's just way too dark and muddy. I did some searches on the internet to see if anyone had some mods for this little combo. There is a lot of people changing the speaker but nothing much regarding the circuit. I did find one mod (here at tdpri) with a bright cap across the volume pot; this helps quite a bit and I used this as a starting point.

    This weekend I spent some time with it and I think I have it where I want it. I'm not an amp tech but rather a hobbyist. I attached a pdf of the schematic and the mods I have done. Its cropped to maintain resolution to post it here but you can find the full one if you search for it on google.
    There are plenty of highs now and it really growls when overdriven. I've gotten it sounding so good, it's earned itself a few Sozo caps ;)

    Here is what I have currently done to it:

    Remove C22 - this is small 47pf cap that dumps some high end to ground before the signal even reaches the pre-amp tube. I'm not sure why this is there but it doesn't help. It can be easily cut off the board. No de-soldering required.

    Remove C13 - This is a common mod found in the Epiphone Valve Jr. called the jp1 mod. Its a jumper wire to a electrolytic cap and when cut, it removes the electrolytic cap from the circuit. With it removed helps brighten the tone as well as increase the gain. On the Bugera V5, it will need to be de-soldered and removed.

    Add a bright cap across both the gain pot and volume pot. This is the major problem causing the muddiness. Many amps have these and it beyond me as to why the circuit designers left these caps off. Anytime there is a signal crossing a 1m pot, and the pot is less then maxed, its going to attenuate those higher frequencies. Installing a small cap across the lugs of the pot fixes that problem. In this case on the Bugera V5, you need to flip the circuit board upside down to add the caps to the two center lugs of the pots. The two outer lugs are ground. I'm using 220pf for both the gain and volume. Depending on how bright you want it to sound is up to you. Anything from 100pf - 500pf will be a good choice. Higher the value of cap, the brighter the tone. Keep in mind the more the pot is turned up, the less influence the bright cap will have. With the pot maxed, the cap is obsolete and out of the circuit.

    Add another small cap parallel to R24. This cap lets some highs pass around the 470k resistor. There is of course C14 which is 220pf that feeds into the tone control pot that does the same thing. But the cap fixed across R24 will allow you back off the tone control on the amp and still retain clarity. Again, I used a another 220pf cap. This will need to "piggy-back" R24, so solder it directly to the 470k resistor.

    By now the Bugera should be sounding really good. With the extra caps in place there will be lots of clarity and more humbucker friendly.

    One last mod I made for additional brightness was to swap out C14 (a 220pf cap) for a 470pf cap. This is the cap that feeds into the tone control pot and allows you dial in your those highs. I wanted this extra treble when using humbuckers with the amp's gain and volume set to ten.

    Finally I installed a negative feedback loop. My goal here was to keep that raw sound but tidy it up a bit. So I settled on a 2.2m resistor. See the attachment for its placement. If you want to reduce the gain and give the amp a cleaner sound, reduce the resistor to something like 22k.

    That's what I have done so far and I'm really happy with how the amp sounds now. I can plug my strat into it and get bright surf tones as well as the ZZ Top grind with humbuckers. The next mod I suppose will be a speaker upgrade.

    I hope this helps anyone with a Bugera V5 who is up to this. There are not many mods for it so I thought I would share.

    Remember to drain the electrolytic capacitors of current before attempting this!
     

    Attached Files:

    eddnix, wb4h, WigWam and 1 other person like this.
  2. mfguitar

    mfguitar Tele-Afflicted

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    Thanks for posting, I may just have to try this.
     
  3. charisjapan

    charisjapan Tele-Afflicted

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    Hey Tele_Wah_Fuzz,

    Thanks for posting those mods, I'll have to look into them (maybe all!).

    Just a speaker change (I put a Jensen C8R, thoroughly broken in) and a set of EH tubes made this a very nice amp. Brightened it up a lot, so maybe all those brightness mods won't be necessary. I use this amp with teles and humbucker guitars, and it's surprisingly versatile. I never use the attenuator (really bad!) and the reverb is mostly useless past 9 oclock.

    [​IMG]
     
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  4. tele_wah_fuzz

    tele_wah_fuzz Tele-Meister

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    I thought the speaker could be the issue too, but before I did anything to the amp I plugged it into my 2x12 cabinet with celestion greenbacks that I use with my jtm45. Maybe my greenbacks are a bit warm too, but I still could not dial in a clear sound.

    As I mentioned in my post, the bright caps across the gain and volume controls are really what made the difference, as it should; a 1m pot will always lose clarity unless the pot is full up.

    The rest of the mods are me getting nit-picky. In fact, I opened the amp back up last night and I'm back to using the stock value of 220pf for C14 :lol:

    One thing to note is the modifications I made to my Bug cost about $1 and I'm getting some really good tones with the original speaker and my greenbacks. A replacement speaker for the Bug is $40- $70 depending on the brand.

    I'll agree with you about the attenuator. It sucks the life from amp.

    The reverb is nice, but I'm usually pretty conservative with it. I keep it around 3. Do you notice there being a rattling sound in the reverb if the volume control is less than full up? With it maxed, it disappears. I know its not the tube cage either because I left that off.
     
  5. everinbloom

    everinbloom NEW MEMBER!

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    I did everything except remove c13 and c14 swap. The results are amazing! I can dial in my dream "highs". Thanks for the pioneering work Tele_Wah_Fuzz! Anyone else on the line about doing this mod;just do it and don't look back!
    Also if anyone needs some 220pf capacitors, I have a bunch and can send you some for cheap! PM me
     
  6. steveage

    steveage TDPRI Member

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    Simply amazing!
    After 18 months of playing this amp, only to put it back in the closet after lamenting the "wet blanket" syndrome, I installed 180pf bright caps on the volume and gain pots.
    Night and day difference! Literally! And not your typical "I replaced a preamp tube with a JJ" night and day difference we all hear about.

    Why they didn't do this at the factory is beyond me.
    Now this amp is usable, Sounds great, And saved me the price of a new speaker as a last resort.

    Now everyone get out their soldering irons and prepare to be amazed!
     
  7. tele_wah_fuzz

    tele_wah_fuzz Tele-Meister

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    Very Cool! Glad you had success with your V5!
     
  8. soulman969

    soulman969 Telefied Ad Free Member

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    To be completely fair opening the amp up tonally wasn't the only reason for or benefit gained from tube and speaker swaps. At least as far as the stock preamp tube is concerned my amp ran much quieter and sounded far better after I replaced if with the Tung-sol 12AX7. I've since dropped down to running a lower gain JAN Phillips 12AT7 and I like the overall effect it's had as well. These are relatively low cost improvements which just leave me wondering why amp manufacturers don't use better grade tubes to begin with?

    I admit that the Emi 820H is pricey but it's also far more efficient then than stock speaker and it not only adds considerable volume but also apparent size to the amp. Hemp cone speakers are also much smoother sounding across the entire tonal spectrum and this particular one adds a significant amount of bottom end as well as taming brittle highs. Mine no longer sounds so mid range boxy as many amps with 8" speakers do and any improvements made to the amp's circuits should be even more noticeable and more appreciated with this speaker or the Jensen 8CR.

    With these improvements already made, and IMHO great value for what I gained as far as the quality of the sound of the amp, I'm anxious to try the mods tele_wah_fuzz did because it can only improve the tone and versatility of the "Bug" even more. The challenge may be doing it myself although if I can wire a guitar I should be able to learn to do this as well. :D
     
  9. Telenut62

    Telenut62 Poster Extraordinaire

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    Really??...Removing cathode caps reduces gain and volume.
     
  10. TheSmokingMan

    TheSmokingMan Banned

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    if you have this amp open for modding you should move R17 ahead of R22 in the circuit and increase R22 to 68K. and yes, lose C22

    as for the cathode bypass cap on the second triode, I'd omit it as well. less distortion at the driver stage will yield more pleasing results from the el84
     
  11. steveage

    steveage TDPRI Member

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    For what it's worth, I traded out the Bugera tubes for a set of JJ's soon after purchasing my V5 due to a noisy preamp tube. I've done a fair bit of tube rolling in my day and appreciate the subtle differences obtained by doing this. I say subtle cause that's about all these old ears can hear anymore!

    The bright caps made a dramatic change. They seemed to take a lot of the boxy sound out of the amp. Probably upping the highs balanced out the mids a bit.

    Love to try out the Emi. But think I'll just play this amp as is for awhile and see where she takes me.

    (Although I'm interested in the Emi 620h for my Fender Champion 600. But I guess that's for another thread!)
     
  12. gcat

    gcat TDPRI Member

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    Well, this thread gets my nomination for thread of the century (ok...for V5 owners anyway). What a pleasantly productive Sunday morning! I've had my V5 (all stock & original) for a couple of years and the tone knob has never been less than maxed, with a TS10 in front to add some treble. So after coming across this thread, I picked up 4 100pf caps at Radio Shack ($3.00?) yesterday, and got busy this morning. I removed C13 & C22, added a 100pf to the gain pot, 200pf to the volume pot, and 100pf in parallel with R24. What an absolutely astounding change for the better!!! Thank you tele_wah_fuzz, thank you!
     
  13. 1960scott

    1960scott TDPRI Member

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    Curious, has anyone regretted any mods made to this amp? I've done all the ones in this thread except the C14 swap and negative feedback loop. My amp sounds much better, but I kind of miss the original dark tone sometimes. I wonder if a C13 2.2uf option via a switch might be something to look into. Might give me the best of both worlds?
     
  14. Mitt

    Mitt NEW MEMBER!

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    Hi, first post, long time reader!

    I'm planning on buying either the v5 or v5 infinium and make some of these mods in stages, as well as experimenting with tubes a bit. This will be my first valve amp. I'm doubting whether to go for the v5 or v5 infinium.

    The guy from ratvalve amps says on his site the new turbosound speaker in the v5 infinium is better than the old red bugera speaker. So that would lead me in the infinium direction. But what I don't know is if the circuitboard is the same as the old v5.
    I mean placing the caps on the middle lugs of the gain and vol. pots is easy, but finding c22 and r24 and so on, it has to be the same circuitboard or I won't be able to find them.

    Anybody know if it's the same circuitboard/resistor and cap. numbers, maybe someone owning the new v5 infinium?
    Just take the chance and go with the infinium because of the turbosound speaker?
    What do you think? I'm close to just getting the infinium and being done with it but I'd like to do the c22 and r24 mods too..

    (p.s. I'm aware of deadly voltages inside amps.)
     
  15. knopflerfan

    knopflerfan Tele-Afflicted

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    TeleWahFuzz - thanks for the info.
     
  16. James64

    James64 TDPRI Member

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    Thank you very much for the great information!

    My goal is to get a little more range out of the tone control on my Bugera V5. Is any one of these mods apply to that directly??? Who knows, perhaps the mod could be put on a switch.

    Essentially I love the Tele/Vox tone (clean and with a bit of break up). I have a Bugera V22 full of JJ's. With all the dials on that amp, I can achieve my favorite Vox tone. I can also make it sound Fendery. Believe it or not, one of my favorite amps is the Vox Pathfinder 15r (8 inch stock speaker). I have a Fender Champion 600 with a Tung Sol 12AX7, a JJ 6V6 S, a Jensen 6" and I replaced the cloth. I also have an older Fender Champ 25SE (12" speaker) as well as other amps.

    I've been trying to make my Bugera V5 a little brighter (making the Tone control a little more useful), without completely changing the character of the amp (I don't want to turn it into a Champion 600 for example). I've been putting off replacing the speaker at the moment, for that reason.

    I replaced the tubes with a JJ 12AXY and a JJ EL84. But still, with my single coil guitars (forget about humbuckers) I can't move the Gain past 3.5 or 4 and the Tone is always on 10. I'm looking for more clean headroom. Putting an eq in front helps but it introduces noise.

    So, I just swapped the JJ 12AX7 for an Electro-Harmonix 12AY7. WOW!!! What a fantastic difference, I can't stop playing it. Now I can put the Gain up to 7 before it breaks up! Now, both the Volume, Gain and Tone controls can be adjusted all over the place. I can find a lot of tones now (even plenty of dirty if I want it), and the amp is much more useful! I actually found a nice tone with the Tone control on 5! Now, I can create a louder clean tone.

    Oh, and I use the EuroTubes tube dampener rings on all my tubes. Helps big time.

    Thanks ahead of time for any suggestions. I hope the information I've provided here helps someone.
     
  17. dmurado

    dmurado TDPRI Member

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    How to fix the Hums Mains?

    Hi Folks:p

    Anyone has fix the hums mains noise replacing the mains plug socket with other one with ac filter on it?

    Is there any other electronic solution?

    Thanks ain advance.
     
  18. James64

    James64 TDPRI Member

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    Update:

    I added a 220 pf capacitor in parallel to the existing 220 pf capacitor in the Tone control part of the circuit. It allowed me to back off the Tone control. In other words the brightest tone that I could get was at 10 and now I can achieve that at about 7. This means that I can finally brighten it up when I want it and yet keep the same unique Bugera V5 tone when I want that. Now the Tone control is actually useful. This coupled with an EH 12AY7 and the JJ EL84 made this a wonderful amp with a Marshall/Vox tone!!!

    Maybe someday, I'll try putting a cap across R14 (in the Tone control part of the circuit), and maybe I'll try a Jensen speaker. But I don't want to lose the existing character of the Bugera V5 because it doesn't sound like anything else that I own (I just want it to be more versatile).

    What would REALLY be great is a sound clip (YouTube) from tele_wah_fuzz (all the tweaks) and from charisjapan (Jensen speaker). That way the rest of us could get a good idea of the end result.

    I don't know about the mains. Mine is quiet, except for the usual hum from single coils.

    Thanks!
     
  19. mpdunne79

    mpdunne79 TDPRI Member

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    I'm in need of some help.... I performed the cap modifications today and I'm afraid I did something incorrectly.

    I removed the C22 and C13 caps. Added 220pf caps across the gain pot and volume pots as described and added the third across the R24 resistor.

    When turned it on (while a little brighter) not the night and day difference described above. Further the amp is WAY louder and breaks up past 3 on the gain (running a Phillips AT7 and a JJEL84) and the volume is maxed after 3 and is much noisier.

    I must say I'm disappointed. Based on what I've read, I must have done something wrong...

    Any help would be much appreciated.
     
  20. dmurado

    dmurado TDPRI Member

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    Verify joints, check valves insertions properly....verify earth loop....I started with these basic steps
     
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