jalexquijano
Tele-Meister
Have read and watch several mods for the Fender Blues Jr. including one which consists on adding a bias pot to this amp. Is this really necessary?
Anyone?
Anyone?
Just bought a Fender Blues Jr. made in mexico
- Thread starter jalexquijano
- Start date
No, no "mods" are ever necessary. There are tens of thousands of these amps doing just fine in the world. If YOU like how it sounds and performs, play it and don't worry.
robt57
Telefied
My only BJR advice is to be gentle if you get into tube trials. It does not take much to tear up the traces on the PCB rocking the sockets. Soldered the traces with bus wire to resurrect the one I got the seller tore up swapping, neglected to mention he was offing a screwed up amp to me...
Traded it towards a Delta Blues 115. I disclose the repairs. I could never get good tone outta it. The guy who traded made it sound fantastic.. It sux suking when you can't get good tone outta an amp know for good tone.
Traded it towards a Delta Blues 115. I disclose the repairs. I could never get good tone outta it. The guy who traded made it sound fantastic.. It sux suking when you can't get good tone outta an amp know for good tone.
I have my blonde 1999 Blues Jr. ( 'a thousand gigs') maintained by a great, D.C.-area tech, who installed this bias pot for him ( not me!) to use when power tubes need changing.
This was done 3 years ago w/last tube change, and all good today ( along with other mods he suggested)- big, clean, and strong.
ElPositivo
TDPRI Member
It is not a ‘must’, but the bias is set incredibly hot from the factory (excet for Blues Jr IV I believe?, maybe someone with a IV can chime in). This can wear out tubes faster than they would if they were biassed properly. The tubes’ bias point is set with a fixed resistor, so to change bias you can either change to a different value resistor or install a bias pot. If you like to try different tubes and / or bias settings it is great to have a bias pot.
Jon Snell
Tele-Afflicted
TheBJ made in Mexico series MkI through III do not reqiure a bias pot. However, to stop the bass response from sounding like you are kicking an old cardboard box around a concrete room, a couple of mods are useful.
Change C25 with 100uF 500v 105°C double ended capacitor, replace R52 with a 33k MO 1/2W resistor, replace C7 with 15n 400v and link pins 2 & 3 of mid range pot, replace C6 for 100n 400v and C5 with 270p 1000v.
This will stiffen up the boxy sound and give you better bass response and full control of the mid range.
The MkIV is cathode biased and does not require adjustment.
Change C25 with 100uF 500v 105°C double ended capacitor, replace R52 with a 33k MO 1/2W resistor, replace C7 with 15n 400v and link pins 2 & 3 of mid range pot, replace C6 for 100n 400v and C5 with 270p 1000v.
This will stiffen up the boxy sound and give you better bass response and full control of the mid range.
The MkIV is cathode biased and does not require adjustment.
jalexquijano
Tele-Meister
Im getting the Tweed version. I believe its MKIII made in Mexico. Also read of people swapping speakers and reverb tanks. All kinds of crazy stuff.
I have three fender tube amps and really love them: Fender Vibroking Limited Edition, Fender The Twin ("red Knobs") made in 1990 and Fender Twin Reverb made in 1994. I just bought this amp to get some nice natural overdrive at low volumes.
I have three fender tube amps and really love them: Fender Vibroking Limited Edition, Fender The Twin ("red Knobs") made in 1990 and Fender Twin Reverb made in 1994. I just bought this amp to get some nice natural overdrive at low volumes.
slauson slim
Poster Extraordinaire
No. Leave it alone. Ignore all the hand wringing and flapdoodle on the ‘net re: mods. Use the controls on the amp and guitar.
jalexquijano
Tele-Meister
Thanks for not letting me fall into that kind of crap. What about the input jack, speaker and reverb tank upgrades?
Jon Snell
Tele-Afflicted
The input jack is a weak spot on these and a Switchcraft or Neutrik Nickel plated brass is the way to go for reliability.
Speaker; Greenback etc will improve the sound. Depends if your pocket can stand it.
Reverb tanks; a matter of preference. I prefer the tripple spring long delay but it only changes the reverb very subtly.
Speaker; Greenback etc will improve the sound. Depends if your pocket can stand it.
Reverb tanks; a matter of preference. I prefer the tripple spring long delay but it only changes the reverb very subtly.
Lowerleftcoast
Poster Extraordinaire
Imo, you should ignore the mod advice,,, for now.
After you get to know the amp, consider mods that might improve the shortfalls you hear.
Mind the advice mentioned earlier. The input jack and the tubes are mounted to the PCB. The traces on the PCB will crack if not handled gently. Likewise, once you open the amp, the ribbon cables and their connection to the PCB are delicate. If they do not have some silicon/hot glue type reinforcement to the PCB, add it before moving the PCB.
IDK, what "low volumes" means to you. An attenuator may be in your future.
The BJR IV is cathode biased, which should have just a *little* less volume. The character of cathode bias tube distortion takes it towards a more bluesy "tweed" distortion, imo. I do not see many suggesting a change to cathode bias, but that is a mod *Fender* implemented. This is food for thought if this is the type of distortion you are after. (This would make the fixed bias adjustment mod obsolete.)
Since you have other tube amps, try some of those preamp tubes in the BJR. Especially V1.
Take your time and do some critical listening.
After you get to know the amp, consider mods that might improve the shortfalls you hear.
Mind the advice mentioned earlier. The input jack and the tubes are mounted to the PCB. The traces on the PCB will crack if not handled gently. Likewise, once you open the amp, the ribbon cables and their connection to the PCB are delicate. If they do not have some silicon/hot glue type reinforcement to the PCB, add it before moving the PCB.
You have already acknowledged the BJR has "All kinds of crazy stuff" suggested for mods. Imo, all of those mods aren't right for everybody.
IDK, what "low volumes" means to you. An attenuator may be in your future.
The BJR IV is cathode biased, which should have just a *little* less volume. The character of cathode bias tube distortion takes it towards a more bluesy "tweed" distortion, imo. I do not see many suggesting a change to cathode bias, but that is a mod *Fender* implemented. This is food for thought if this is the type of distortion you are after. (This would make the fixed bias adjustment mod obsolete.)
Since you have other tube amps, try some of those preamp tubes in the BJR. Especially V1.
Take your time and do some critical listening.
Telenut62
Poster Extraordinaire
Except BJ's are biased ridiculously hot, which leads to issues.
58Bassman
Tele-Holic
Depending on the version, it may be based too hot and if it is, tubes will die an untimely death. Best to be careful.
Sea Devil
Friend of Leo's
My tweed Mark III is unmodded and has had zero issues other than needing a replacement tank.
Greenmachine
Tele-Afflicted
Don't mod. Save up and buy a deluxe reverb.
Sound advice. I've owned a couple of those amps (both the US version and MIM) and foolishly went down the rabbit hole of modifications on my first one....waste of money and time which is why I purchased a new one without mods.
They are a good sounding amp as is, no sense in jamming a bunch of mods onto it.
jalexquijano
Tele-Meister
But what about the jensen speaker replacement to eminence or input jack to swithcraft?
Speaker replacements are always personal preference. The Switchcraft jack is obviously better, but once again, this is Fender's second-best-selling amp of all time. They can't be totally terrible with parts ready to fail if that were the case. I'd use it as is for now, and if you do develop an issue or when it comes time for a service, you can always change things then.
jalexquijano
Tele-Meister
Thanks for your the time spent rendering advice. Ill use the amp as it is.
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