Done-ish | '75 Fender Champ Pt 4

[@BradsGuitarGarage]

Thanks for the shout out, fella! And beautiful work as always!

[@matthewf1979]

Australia is blessed to have Brad’s Guitar Garage! He does perfect work on some of the most haggard, destructively modded and most hopeless amps on the upside down parts of the world. I still can’t figure out how he stands on his head all day and does such wonderful work. Cliche Aussie jokes aside, He really is a master at rebuilding anything guitar electronics related. …And Lyle…well, you can see his results here. Just fantastic work and has taught me a lot of new tricks.

[@RaymondLau-u7x]

This is one of the most fun series Lyle has ever posted. Everybody loves fender champs!

[@jonathanj-g-yyelle6144]

Agreed! I love 'em even more now after watching the series.

[@larrychung3190]

Excellent work and demonstration as usual. (: All amp techs who charge money should have to completely rebuild a 70s Champ. Or even a dozen. A simple circuit offering so much in the way of flexibility (and possible modifications, sure) and a great insight into how so many more complicated amps work. So many good lessons on the importance of each element and how it all works together - as well as lead dress, component location, overly-long wires, consistent quality soldering, wax-impregnated eyelet boards, you name it. Not to mention properly and lovingly fixing a nearly 50-year-old vintage amp. Thanks for documenting this all. (:

[@tomoshea5683]

I like it better with the paralleled resistor, but nice either way!

[@DavidWren-u3k]

For the mids resistor maybe use a CTS 250k pot that has a push-pull switch to enable either 15k or 7k to be selected Normal position would be 15k Pull out the bass knob and the additional 12k mid resistor in parallel with the 15k mids resistor will create a 7k mids configuration It is transparent modification that works nicely

[@SirLoinMagroin]

That 15k in parallel reminded me of a BBE Sonic Stomp pedal. Like taking a blanket off of your speaker cab.

[@gpower]

Nicely done Lyle! I'm soon going to rebuild my '78 Vibro Champ. I bought a parts kit from the Fender amp guy in Cali and asked him to include a 6.8k mid resistor, per your recommendation. Hearing it in the compressed KZbin world, I know I'll like the tone better than the stock 15k. I'm sticking with the 4ohm speaker and using a G8C from WGS.

[@garygratzer9670]

Wow that resistor change was transformative. I personally like the 7k

[@stokerdon1020]

I guess I never saw inside a Silver face Champ. It looks like the same chassis, power switch, sideways tube sockets as my Musicmaster Bass amp. I am currently rebuilding it and adding a tube phase inverter. I also added chassis soldered grounds near the pots and jacks like on this Champ. This video was very helpful. Thank you,

[@chrisfit]

Just picked up a 72 Champ yesterday. All original. The volume pot works but you can keep spinning it past the 1 and 10. Weird thing is turning the Treble down decreases the volume to almost 0. Even with the volume up. Going to start with replacing the Volume pot and go from there. The wiring also has that green goo at both ends. I’ll be replacing that. Thanks so much for the great content.

[@qua7771]

Sounds like a find. It would make me wonder if you can find a NOS matching pot, or something that looks like it belongs. I guess new production works as well.

[@DanielC__]

so you can turn it up to 11… 😂

[@goodun2974]

The pushed-in notch in the metal rear casing of volume and tone pots isn't merely a place to squirt control cleaner, it functions as a stop so the control can't rotate continuously. The rotating plastic disc that holds the wiper should have a protruding plastic tab that stops when it hits the notch in the metal case. The tab is probably broken off and rattling around in the control or inside the amp. The control might be repairable; nylon is difficult, almost impossible to glue but maybe you can melt a small nail or wire brad into the nylon disc with a soldering iron to function as a stop by hitting that metal notch. It's worth trying, and even if you fail you'll still learn something! 🙂

[@ditchgator1]

Big difference in tone from one change. It would be cool to have that switchable...?😎👍👍

[@goodun2974]

Yeah, Champs tend to be a bit midrangey and muddy for my taste; it sounded much better to me with the lower value mids resistor.

[@GhostfaceGriller-hd7jw]

Awesome neat work as usual 👊😎

[@sgt.grinch3299]

So many options to get a signature sound.

[@IainThacker]

Having just made a simple repair to a failed amp - transformer secondary fail, common fault on that model Marshall, I think a Champ might be a nice place to try building something from scratch! Hopefully using some of the info gleaned from this channel to do it well!

[@jutukka]

Funny that I have had several amps featuring a Fender tone stack with a middle pot. But I have noticed that I actually don't need an adjustable middle control at all because I tend to keep it in the same position anyways even almost independent of guitar or speaker used. And I have measured the optimal value and it means in my case around 7.5-8.5 kohm. That original solid 15k is usually absolutely too much for my ears. Going to much smaller values than about that sweet spot increases the load the plate of the driving stage which can be in certain circumstances seen easily as a distortion when feeding the input from sine wave gen.

[@oldguy5381]

Job well done, time for coffee

[@MrMrjauregui]

Love it!. Building a vibro champ now (mojotone). I was considering putting the 8 and 4 ohm taps on a switch. I just may end up using the 8 and putting the 4 ohm tap on the resistor like you did here..

[@DanielC__]

great work Lyle, really enjoyed all your videos

[@retread1083]

Other factors such as B+ voltage, plate current, and actual load impedance, matter. But in general, 8k primary impedance is a better choice for a SE 6V6 and 5k is more appropriate for a SE 6L6.

[@LarsonGuitarPlayer]

I'm in the process of learning how tube amplifiers work and this video was, as always, very informative. However, I preferred the 15k mid resistor. Probably because of the more gain. You seemed to prefer the cleaner sound?

[@WayneMemphisMojo]

Ever think about putting together a recommended parts list for various amps? Or would this lead to “DIY nightmares”

[@Satchmoeddie]

I have had some techs tell me to put the hot wire from the mains cord go to the switch and then to go to the fuse, so the fuse & fuse holder won't be live. What is the first primary rule of safety regarding servicing anything electrical or electronic that plugs into a mains outlet? UNPLUG IT FIRST! I have had those Carling toggle switches short to ground.

[@goodun2974]

Putting the switch first in line with the incoming hot lead won't turn off the voltage to the fuse if the wall outlet is wired backwards (nightclub electrical systems are notoriously dangerous). Anyway, I think perhaps America should use double-pole on-off switches like they do in Europe, so that both hot and neutral are disconnected when the switch is off.

[@PsionicAudio]

Yup. Switches can short to chassis. And the law is that any device like this must be fused first. Period.

[@ToddRichmond]

"oh what a diff'rence, a resistor made. 15K little ohms..."

[@victorbeebe8372]

Aloha Lyle! Is the Owner going to bring new cab and speaker? If so, You going to test it with new cab?

[@PsionicAudio]

All on order. It’ll be a bit.

[@189pinto]

Where do you get that white wire? I need some.

[@PsionicAudio]

That’s top coat 22AWG from valve storm.

[@189pinto]

@@PsionicAudio Thanks!!

[@ethelwulfmountbattenderoth2286]

Whoa, speak of the Devil. I have a '73 Champ that is still in very good condition. I've never played it. I've just been lugging it around and putting it in storage. A tech told me a few years ago that it looked to be in good shape. However the speaker cone is basically dust. Is it worth it to recone the original speaker for Original condition for possible re-sale, or should I just put an appropriate speaker in it's place, Webber, Jensen or whatever? Whether or not you reply, I still want to thank you for your channel. I'm learning a lot.

[@PsionicAudio]

Thanks. The original speakers in these aren’t great. Get a new one.

[@ethelwulfmountbattenderoth2286]

@@PsionicAudio Wow, thank you. Will do!

[@SirLoinMagroin]

That 15k in parallel reminded me of a BBE Sonic Stomp pedal. Like taking a blanket off of your speaker cab.

[@LarsonGuitarPlayer]

I'm in the process of learning how tube amplifiers work and this video was, as always, very informative. However, I preferred the 15k mid resistor. Probably because of the more gain. You seemed to prefer the cleaner sound?

[@PsionicAudio]

I just wanted to do a little mini lesson on what a difference that one resistor makes, so players can be more informed about their amps. Doesn’t matter what I prefer - this will be the client’s choice.

[@goodun2974]

​@@PsionicAudio, Most 8" speakers in a Champ are going to be somewhat mid-range heavy anyway, so I definitely preferred the paralleled, lower value resistors. It will be interesting to see what the customer prefers. Were you running this through your shop 4x10 or 4x12 cabinet?

[@PsionicAudio]

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