Crawls Backward (When Alarmed)

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Piercing the Veil of Grill Cloth

Things are moving at a semi-dizzying pace here in Yr Fthfl Blggr land. Projects are crashing all around. Well, not literally crashing, but there are a number of things in de woiks and many many things in my head to work on. I'm trying to keep up on de ol' blog but this, too, is a project!

Not only project, but the parade of packages that are being delivered to the old homestead several times a week. I've taken to leaving milk and cookies out for the UPS and USPS delivery folks as a bribe to keep trudging up the path with more boxes of goodies.

I did a project last fall in which I converted a current-issue Fender Champion 600 guitar amp to a classic 5F1 circuit. There was a long thread on the TDPRI where I did a more-or-less step-by-step essay on it. My intent is to pull that thread over here, but who knows if I'll actually get A Round Tuit. In the interim, you can read the thread if you'd like. Fun for all, actually.

If you know what I mean.

A number of folks who have the popular little Champ 600 have commented on the rather ugly and heavy grill cloth that comes on the critter out o' de box. I have to agree.

Whilst I was perusing the MojoTone website for Tele parts the other week (for The Red Tele project), I saw they were offering early-60s Fender "oxblood" style grill cloth for a nice sale price. I ordered a yard of it and went about re-grilling my Champ.

Turned out to be fairly straightforward for the most part. The first thing we gotta do is take the chassis out de amp. Four screws hold it in - two on ze back and two on ze side. We also hafta take of the back panel. This is all easy stuff.

Now we slide the chassis out. If you've seen the build thread, you know I took the whole PC board, power transformer and output transformer out of the amp. So if you, dear reader, are going to change the grill cloth on your Champ, your chassis will most likely not look like mine. Mine looks like the picture - it's an 5F1-style eyelet board.

Out comes the baffle board - aka the piece of plywood board the speaker is mounted on. There are four screws that run through the front panel of the amp and are bolted on from behind. They were easy enough to get off, but you'll need to hold the screws from the front while you undo the nuts.

To take the nuts off, I used my trusty Sears Craftsman nut driver loaded with an 8mm socket. I know whatcha thinking. Ain't dis an Merikan amp? Din't Fender useta use 11/32 nuts on their speaker screws? Well kids, it was designed in the USA, but it's built in (three guesses and the first two don't count...) China. MMMMMyup. So we gots dem metric fasteners. No is problem, I speak metric too. And have the tools to prove it.

After twiddling the driver around and around and around, the nuts come off and ve can take ze baffle and speaker out. Whoo hoo. Now the real fun starts. We gotta take off the old cloth and put the new one on, which to paraphrase George Harrison is "what we came for." (Concert for Bangla Desh reference).

Wow. Yikes. Zowie. Nine zillion staples holding the cloth on! And they're half buried down into the plys of the plywood that the baffle is made out of. I am scratching my noodle over this a bit. I tried a coupla different screwdrivers to get the staples starting to pull off until I got a method: with the baffle face down, use a small screwdriver to pry them up a bit. Then make a second pass with my trust Craftsman needlenose pliers.

After about 30 minutes of that, the cloth comes off. And the folks on the TDPRI were right - not only is the cloth unattractive, but it's fairly heavy. I would think this is not good for our Fine Tube Tone Our Amplifier Produces. But ve gonna change all dat, yes?

I wound up with a small pile of pulled-out staples after getting the cloth off. Off to the dustbin with you, I say! The Chinese are making this stuff and it's winding up in our landfills.

Now, we are going to cut our new grill cloth and staple it on. I thought originally I would need to use a spray adhesive on the board, but the baffle is so small I don't think it's needed, plus they didn't use adhesive originally. We should be ok with just staples.

To drive our staples (I used 3/8" if you're counting), I get my trusty Arrow staple gun. This thing is like the best $15 I ever spent. One of the best things about it is it's made in Saddle Brook, New Jersey, USA. You gotta problem wit dat?

Needless to say, the yard of new grill cloth I have is about nine-tenths of a yard more than I really need. Guess I'll have to build another amp to use it up, yes? This is more Fender-authentic I think - even though it's what they used on white Tolex amps in the early 60s, it still looks appropriate.

We hack the appropriate amount off, and staple it to the baffle board. Notice I can't staple in a straight line and in fact the nice Chinese people who assembled the amp would fire me if I was on their assembly line. But it works and who will see it? I have a bit of excess I trim off with scissors.

I won't bore you with the reassembly, but it is (as they say) the reverse of diassembly. Here's what we wind up with. I like it. And the lines in the cloth are straight. I musta done ok.

While I have the chassis out, I'ma-gonna mess with a 'bright' cap on the volume control. Fender (and others) use a small value cap on one channel of their two-channel amps. Consequently, this is the "bright" channel. It has a touch more crispy high end with the cap than without it.

For some reason, this amp sounds a bit 'dark' to me with my Tele or Strat so I'm seeing how this sounds. I experimented with a couple of values - 100 pf (picofarad), 68pf and 47pf. Fender themselves used 47 on some amps and 100 on others (usually the smaller amps got 47 and the bigger ones got 100 but that's not always true). 100 was too bright and 47 was just right.

Now off to play it and see how it sounds.


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