Tech Tip : Shielding Vintage Fender Amps

[@weschilton]

Hey that's not only functionally great, but you did a fantastic job of blending it in to the look of that vintage cloth wire. I really appreciate your attention to detail!

[@michaelnewell3823]

I was wondering if you could tell me where to buy this particular kind of shielding wire in the United States.

[@fiddlix]

Great job Lyle…An excellent video on a common problem in Fender amps…especially in the blackface and some silverface amps.

[@davidlemnah4938]

Hi, Can you share what shielded cable you would recommend?

[@Mr.T711]

Quite a difference after the wire replacement. Interesting stuff.

[@jutukka]

Grid stopper resistors are in the wrong end of the input circuit as well in those Fenders (and in most other amps too, because of that easy component layout and input impedance switching option done by input jacks), which does not make things any better, whether shielded in chassis input circuit cable is used or not. I never do the wiring (from input jacks to the V1 grid) like Fender did it in my amps, because I almost never need that low impedance input option, and if I need it, I do it differently, to minimize all unwanted noises. In those amps which are built in a way that chassis and missing or inadequate shielding of wooden cabinet does not form a good Faraday cage, the problem of unshielded input wiring is of course inevitable especially in case of high gain amps.

[@goodun2974]

Lyle, I swear you and Ted Woodford time your videos to come out within minutes of each other! Yours is shorter and easier to watch while I am cooking.....

[@ColbyJohnson303]

both are the kings of what they do!

[@ditchgator1]

Big difference indeed 😉😎👍

[@MobiusGuitars]

Is this RG-316 you're using?

[@chipsterb4946]

Lyle: do you ever use shielded wire for the return from the 12AT7 to the Reverb pot? That’s a small, relatively low signal.

[@PsionicAudio]

Nah. Not needed IME.

[@chipsterb4946]

@@PsionicAudio I’ve seen builds on the AX-84 forum that have almost as much shielded wire as normal …

[@Elektronijaenis]

And some people also seem to think shielding the guitar also kills the treble... And then they run long curly "telephone" -style cable from the guitar to amp. Maybe 10 cm of shielded wire in the guitar vs. 10 meters of shielded wire from guitar to amp and the wire in the guitar kills the treble. :D

[@ScottyBrockway]

I plan to do the very same thing to my '68 bassman.

[@michaelvarty-brownstein3977]

What are the little blue caps you're using in the tremolo circuit?

[@PsionicAudio]

1KV TDK MLCs. Will never fail.

[@michaelvarty-brownstein3977]

@@PsionicAudio Thanks

[@jereskelin2177]

I'm thinking of buying a vintage bf pro reverb but Im not sure how useble is it stagevise. I play small to medium gigs so Im afraid the pro would be to powerful for that. Would a deluxe reverb be a better option?

[@weschilton]

They are different sounds.... however a Deluxe can still get pretty loud, although you will start to overdrive around volume 4-5. It all depends on the sound you are looking for. And there is always the attenuator option if the gig is ultra quiet.

[@russellhltn1396]

What would be high quality shielding? I've got some RG-174, but at "50 ohms" (at RF frequencies) would it be too capacitive?

[@jimsalman7257]

Do you own a capacitance meter? (If not I highly recommend getting one.) Cut a 10 foot length of the cable and measure C between shield and center conductor at one end, after making sure they’re not shorted together at either end. Measure and divide C by 10 to get C/ft of the cable in question. Anything less than around 50 pF/ft should be fine for the short runs you’ll need inside an amp chassis.

[@PsionicAudio]

Ohms is resistance/impedance. Doesn't come into play in this application. Different RG174 cables have differing amounts of capacitance. There are some other RG specs with larger diameter inner conductors, less prone to fragile connections. Good cable vendors list the capacitance per meter. @80pf/meter is not uncommon. Given the short lengths we're using, that's low capacitance.

[@ronfrey5327]

@@PsionicAudio what may I ask is the cable you used here Im using 174 but have no sound ive sent an email regarding that but I like the results with the wire you use wondering where I might find it. Im in Texas btw and have some bassmans which id like to send.

[@zacharyharris6311]

​@@ronfrey5327 did you ever figure out what wire and where to buy it? I'm dealing with this same issue with two blackface amps.

[@Matan2222222]

What kind of cable would you recommend?

[@JohnnyFaber]

Mogami makes a great cable from my experience. But i am curious if he uses something different as well.

[@tomk1tl39]

I usually use RG174......also RG316 (teflon) can be used....a little more $$$ but dielectric will not melt !

[@johnmarshall3903]

Psionic, what brand/type, guage do you use? Thanks

[@tjminasi1442]

Yes, manufacturer

[@johnwilliamson467]

Grounding and shielding techniques in instrumentation 2rd. By Ralph Morrison abebooks about 8 dollars . Nice reference to this problem good job there. When dealing with fanboys facts, reason , and field work with the knowledge do not help . When dealing with result oriented people that knowledge is of great value.

[@danielsaturnino5715]

Electromagnetic noise is all over the place these days... everything must have shielding and filtering and such. Acoustic guitars just dont care :)