How to repair enhance gain performance Fender Silver Face Vibro Champ tub guitar amp easy mod 

The tips on the change in plate resistors is just what the novice needs to here, anyone with a soldering iron can make that change. Thanks

YES! "Born On the Bayou" with the Tony touch! Sounds much "bigger" than a Fender Champ now.

I was there! My first amp was borrowed from a wealthy friend, a 1964ish Fender Pro Reverb.. dual 12". After moving, and having to return the Pro to its owner and his vast collection of Fender amps, I found my own Fender, last run of Blackface, Vibrolux Reverb. We knew these were good amps back in the day, but had no clue that they would become legendary. The Blackfaces and early Silverfaces remain among the best amp line ever made in mass production. Nice to see you fixing this gem up. The gain mod is a great tip. 100K is a little low for a 12AX7A. YES much better to use above 200K plate R on 12AX7A to get more gain.

After finally getting around to it, I did the modifications that you described, changing the Grid resistor to 560 K, and the plate Resistors to 220 K. The difference is absolutely incredible. It's a completely different amp. It has more punch, more power, and a Stratocaster through it makes it sing. I consider this to be a genius move on your part. So much so that I made the same changes to my 5F1 Tweed Champ (from a kit). I thought it would have the same effect. It did. I'm planning on doing this to every Champ I can get my hands on. The VibroChamp that I initially did this to now has a happy new home with a harp player in Vegas. He thinks it's a miracle. I didn't have the heart to tell him it's only three resistors. Keep up the good work, my man.😅

Wow, you've made that amp come to life Terry.... well done... It's easy to tell when an amp is singing nicely just by looking at Tony's face... awesome brother.

Completed all the mods on my '79 VC today, and I can attest that this video is 100% as advertised! Wow! Couldn't be happier with the new-found chime! And if you've never played through one before, it also has the best tremolo circuit Fender ever designed. Telecaster master, Jim Campilongo, will attest to that. Thank you much, Terry!

I have the exact same amp. I will have to give these mods a try!

In my 1979 all original Vibro Champ, the bias resistor has drifted to 531ohms, and the plate dissipation of the original 6V6 (with the original 5Y3 Rectifier) is 16.7 Watts, or 139% of "maximum". I will be replacing the resistor with a 1K ohm or perhaps even a 1.2k ohm. You stated that the stock capacitor in the bias circuit is 25uF at 50Volts. Mine has a 25/25 cap. I do have a 25/50 on hand, but I may pick up a 100/100 as you suggested when I buy the bias resistor(s).

The best sounding Champ I ever heard

Terry, You have obviously done your magic on the tremolo, Great sound!!

A re-born Fender amp..christened with CCR...nothing can stop it now.

I see Tony re-strung your guitar! Nice repair. Sounds great!

Looks like you got a vacuum tube bobbing in that wine glass you got there, OM!

Excited now to do these mods and upgrades on my '79 VC, which has always underwhelmed me with its blah tone. Thanks so much for posting!

Nice fix Terry..Great sound, from Tony's picking..love it..Ed..UK 😁

You're an Ghoulardi (Ernie Anderson) fan? Cool! He was also the announcer famous for "...this week, on The Luuuuuuuv Boat."

Another great job by Terry , Marsha the bartender and guitar by Tony........I"m really surprised that you don't have 100K+ subscribers. . .great tutorials !

Red wine with tubes! - Your wife is worth gold! By the way ... a nice and informative video. Keep on the good work! 👍

Great video! Thanks for sharing some more tips and tricks. I’ll probably watch this again with the schematic to better learn the “why” behind the modifications made. Really cool stuff

Watching from Columbus Ohio USA

Terry, if Tony had come to my house playing guitar and wearing that Knights of Columbus shirt in the 60’s my dad may been more accepting of my guitar playing. The only guitars that were supported at our house were at the Saturday 4:30 Guitar Mass that my old man said the “cool kids” went to. I used to take the dollar that my dad gave me for the collection basket and go to the music store instead.

Excellent as usual Terry. My vibro champ has been running the 6v6 hot. You've just told me why. Great info. You are quite the tube guru.

Cant wait to use this on my champ. Well done

You really do a nice job with the mods and the presentation.

All the wishes for the 100k subs Terry, you deserve it! How about something on a small tube bass amp design?

sounds awesome Terry.

The AMP sounds great! Is there not a hot, rocking, young player to really fire up these amps? Love Tony but once in a while a musician would really be a welcome addition.

Hey Terry, I have been playing the modified Vibro Champ daily for two weeks now and it sounds amazing. Great job on the mods and excellent video! Kevin J

“I can’t say no”…..(best line on RU-vid!)

Great stuff! Thanks for sharing your info on raising the gain to preferred levels! I mention your channel every time I get a chance. Good luck on 100k !

ótimo vídeo congratulações Jorge Sul do Brasil

Great sounding mods Terry, thank you for sharing.

Tony is awesome!

That's one happening amp Terry!

Very cool mod! Thank you!

Interesting, and sounds great. but I'm a little confused . the tubes tested with "excessive gain" , but were actually 12AT7 instead of 12AX7. the gain factors for each tube are (approximately): 12AX7 = 100 12AT7 = 60 So how would the 12AT 's be more excessive? Then you made your upgrade for even more gain - but we never heard the amp with just the correct 12AX7s for comparison

Excellent. I'm betting a blurs harp player would LOVE that amp

What a difference. I plan to mod mine accordingly! One more thing. Is that a Cabernet or Bordeaux? Could be Merlot though. Whichever, they all are good.

The original owner who bought it in 1980 and has been sitting ever since but yet has had work done on it? Maybe somebody lied to the original owner.

Happy Twenty Twenty TUBE!

Next time a Champ or Vibro Champ 6V6 is running over-hot, try increasing the value of the dropping resistor in the power supply that runs to the screen filter node (here, 1kΩ). That will lower screen voltage, which will lower plate current. But better, retaining the lower-resistance cathode resistor retain sensitivity at the 6V6, because bigger bias voltage = bigger signal required to distort the 6V6.

Hello! Your videos are awesome! I learned a lot about my VC thanks to you! I have a little question about the mod. My VC is already running a little hot on the preamp tube plate (around 240V). Could in my case this 220k plate resistors damage the tube or the tone stack caps? Thanks!!

I need to do this to my Vibro Champ.

I have a late seventies early eighties 100 W Ampeg tube combo amp that recently stopped working would like to find a way to get it to you

Your wife has got to be just as crazy as you are. Cheers! AF 427X5.

there is nothing wrong with silverface models up to about 74 and even then it is the big box models that have some issues (most of which are fairly easily modded away, and that is if you think there is an "issue" in the first place. I actually prefer 68's as i like the aesthetics of the drip edge and they are the exact same circuits - in fact most of the AB circuits are improvements over the AA ones

Fenders are SO nice to replace components compared to a chassis from something like a Hammond organ. Those things are incredibly well built but will take weeks off your life working on them.

Love the power tube in your glass of fine wine, lol.

Great channel. Maybe the best one. Is that a 12ax7 floating in your wine at the end?! Question : Would swapping out the 100k resistors for 200k work on a 5f1 build? And does anything else need to be adjusted in order to “bump up” the capacitance of the cathode cap(s) like you do on these? (Other than adding the new value caps)

What are your thoughts on adding a switch to lift the tone stack out of the circuit, rather than changing those resistor values? Was your intention here to do this without modifying the chassis at all, or do you think there’s a tonal benefit? On my silverface champ (non-vibro), I did the tone stack lifting switch, and also added a negative feedback (removal) switch. Between the 2 mods, I found that I can get the silverface to behave very close to the Tweed Champ.

So in a Fender Deluxe Reverb that has two 6V6 tubes and two 220k grid resistors. Does a single 6V6 sees a 220k or a 440k grid resistor ? Cause that would make a lot of sense bumping up that grid resistor.

Hey man, have you heard of a rare vintage sano 300s tube amp?

Great job as always ... If only I could sub more times ... :) I'm sure you will succeed in your goal for 100k.

Any of you guys try swapping the two power dropping resistors with each other? Seems like a fairly common mod to keep the grid mellowed out with such a hit bias. Curious if anyone has any strong opinions on that.

Damn I wish I was testing these . I wanna hear a strat and srv through that one

subbed!

Hey D-lab. From experience I can say drinking wine and poking about HT B+ supplies is not a good mix

Saved into the file, your videos are always good. Keep up the corny, that "beckoning forth for the wine" could turn into yer signature intro real funny, real fast. Gong show with hot solder and trippy oscilloscopes

Wow, the gain is to much for the Celestion 8-15 (15 watt). External 12" speakers do work well.so I know the weak link is the speaker. I want to keep the speaker in it. Should I back off on the 560k resistor to 440 or 320k to tune it better to the 15 watt speaker? Would the 220k resistors be a better source to back off on? Around 6 on the volume pot starts to get bad distortion as is. Thanks in advance.

HI, I have my dads dynaco 70 built in 1966 and i want to get it working, If i cant can i send it to you. Thanks

Are You Still With MojoTone?

Can we put a potentiometer to set cathode bias?

Hey Terry, what happened to Mojo ?

Sounds good, but just so long as there isn't any mercury leaking from that tube in your glass. ;)

Once you install a 3wire power cord in the fender amp can you put a death cap from the hot lead in series with a 1meg ohm resistor to chassis ground? Would that help with Noise filtration With out causing a shock hazard?

Would like to have heard some bass tone on this amp…

560k is hard to find. what about half meg. If I have to, I can get them from Mouser.

Thanks Terry D. For the tips on the champ amp I have a 66 black face Champ that I added a Tremolo cirquit to. I will be doing those Resistor adjustments I do have the 1k on the 6V6 cathode. I'm putting in a new Can cap with 40 20 20 I know it might be alittle Hard on the 5Y3 but it Helps with hum. I'm puting 2watt res. In the 1st and 2nd B+ nodes making it An AB instead of an aa764 cirquit. See you more on Utube. Dwight.

Your Good

Doesn't increasing the plate load resistor result in a decrease in plate voltage?

Tony!!!

and less amplification?

How many watts does this put out?

That’s the funniest thing I ever seen !!!!

cool

👍👏😊😉

R.I.P A.S.D. headphone users at 4:16 Edit: Why have you got a 12AX7 in your wine glass, sir? I feel I might be missing out on something here..

to get 100k you may need some youtube guitar stars on there maybe pete thorn?

your wine is tubealishis

Keep the booze away from Tony before you let him try to play on the videos. Lol

Me thinks that feeding Feldman fermented juice of grapes, prior to his minstrel performance, isn't paying the dividends it has on other videos, lol...