Tips for the sexiest offboard wiring!

[Ronsonic]

You raise some good points, Gabriel. Leo was very enthusiastic about keeping costs down but only in the context of producing pro-grade instruments. His stuff could have been built cheaper but it wouldn't have met his reliability standards. His approach to "student" amps was just a smaller, simpler version of the big stuff. Look at old Danelectro, Valco, et al for how things might have been.

I don't know that your comparison between Fender and Hiwatt is fair. Both have jacks and capacitors and those parts fail far more often than anything else and both companies used top shelf parts. I've met both Fenders and Hiwatts with failed transformers and both probably in proportion to their market share. The one failure I have seen that is far more common in Fenders and is related to construction practice are failed solder joints. Especially the one resistor that runs lengthwise on the board. This is the area where turret boards are superior to Fender practice. As much prettier as the off-board wiring is on the Hiwatt the only functional improvement on Fender practice might be the buss wire ground on the back of the pots over the grounding plate.

I'm willing to bet that Doug does better, cleaner work by accident than a lot of guys, just from habit.

[MR COFFEE]

OK, folks, I guess I'll weigh in on this wiring business, FWIW.

My summer job after HS was wiring navigation systems for Flying Tigers airplanes. It was mil-spec, and my supervisor and the inspectors were VERY picky. It was all 19-stranded Teflon except for long fuselage runs which were nylon over fiberglass insulation, and the boss explained why that was, but it never made any sense to me.

Did we run wires parallel to each other and tie wires together? Yeah, a lot. Why? Because cabling with "service loops" was what was demanded by mil-spec. And in a vibration-sensitive environment, cabling reduced vibration-related breaks. How do I know that is actually true? Well, I don't. I asked my boss why they used all that finely-stranded wire instead of solid, and why we had to cable everything. He said that if we used solid and didn't cable it together like that, that if we put in on a truck and sent it to California (across the country), that a dozen connections would be broken by the time it arrived. He had worked electronics and military contracts for 20 years then, and he didn't seem like the bullshitter type. Pretty low key and facts-is-facts. He said he'd seen it done, and "it was a nightmare" to rework it.

Does that mean that we would run low level input signals next to output signals, or AC hum sources? Of course not. That is just plain BAD lead dress.

Square corners? BAD lead dress. Increases the chance of wire breakage. And it you want to know the real low down on mil-spec wiring, we had to use "anti-wicking" tweezers than placed a heat sink around the stranded conductor where it entered the teflon jacket, so the solder when you tinned the lead wouldn't wick up under the insulation. The rationale? (You know I asked). The inspector couldn't see a broken conductor that might be up under the insulation, and the most likely place for a wire to break was the junction between the solder-tinned-solid part of the wire and the regular stranding. And there was more, too. Don't tin the stranding so much you can't see the stranding; that's over-tinning and reduces reliability. You had to bundle the wires together just so and tie it every inch or more often if a conductor exited the bundle. Picky-picky-picky.

There was more, but you get the idea. Did it look pretty? I thought so. Sexy? Umm, I guess we all have different ideas of what is sexy, and mine has more to do with flesh and blood. Of course, I've heard that some jet pilots get a hard on before a carrier take-off, but it just doesn't translate somehow..., for me anyway.

mr coffee

[joegagan]

great post, mr coffee. i appreciate it.

in the case of the pre-tinning heat sink tweezers, were you supposed to leave a short section untinned wire between the jacket and the wire so a future repair person could see that the tinning did not extend under the insulation?

[skrunk]

I find some of that super straight wiring a bit disturbing to be honest 

I think you can still be neat and tidy while letting the wire curve more naturally.

[MR COFFEE]

WARNING - PERSONS WITH OCD TENDENCIES SHOULD *NOT* READ THIS POST. IT MAY BE HAZARDOUS TO YOUR HEALTH.

Hi Joe and all,

in the case of the pre-tinning heat sink tweezers, were you supposed to leave a short section untinned wire between the jacket and the wire so a future repair person could see that the tinning did not extend under the insulation?

That was the general idea, except they inspected the hell out of everything before it left the building, so there was never the chance of it getting to a future repair person if it wasn't right to start with. And I suppose part of the idea was that if a wire broke where the tinning stopped, a future repair person could see it easily because it wouldn't be up under the insulation. Planes do shake and jerk around a lot, which wiggles and tugs on the wiring, so I guess it made sense. Much harder on electronics than drunk roadies, I expect.

Another inspection purpose of the "perfect-tinning" was so you could see the stranding. That way the inspector could also verify the connection as "less than 3 nicked strands (out of the 19), no strands missing" from how we stripped the wire.

Mostly we used thermal wire strippers, except where you couldn't get to it to strip the end without risking melting something else. I still use one I picked up at a hamfest, and I'm still hooked on 19-strand PTFE. In my active electronic guitars, the boards connect with cabling with service loops to the controls so you can get it out to work on it without over-stressing the connections on either end. Those little nylon cable clamps are great if you've got lots of connections you want to protect from bending at the ends. Camp the cabled wires at both ends of the service loop, and the only thing that flexes is stranded wire well away from the connection points. I learned that at Decca, too.

No ty-raps either - You had to make hand ties with woven nylon tape impregnated with micro-fiber anti-fungal wax. And you had to tie them a certain way, too, so if the knot came off, the tie wouldn't unravel without some real coaxing. Picky-picky-picky.

And BTW, you *can* run low level inputs and high level outputs near and parallel to each other in bundles if you use shielded cable for low level leads.

All of which seems like overkill for most anything we do around here. Although I do shield leads from input jacks from time to time with small diameter shielded wire if the notion strikes me it might be a good idea. Is it necessary? FIIK <LOL> I don't do production work, mostly one-offs. Every once in a coon's age I get somebody who wants ultra-reliable stuff, but the cost for the extra labor involved, top shelf components, and protection circuitry don't make sense for anybody of normal means IMHO. There are compromises well shy of mil-spec that may make sense for some heavy-duty road warriors. FWIW, I don't like cheap unsealed pots, and I think the extra cost for quality controls makes sense. Of course, I *hate* noisy stuff, and scratchy pots get under my skin. Just me.

@skrunk

I think you can still be neat and tidy while letting the wire curve more naturally.

The inspectors would have reamed us out if we did that kind of stuff. Square corners were verboten. Just another place to cause wires to break in service. They prescribed "fillet" curves for various gauges of wire as they approached bends and terminals. Squarer than that, and you got re-work tags. It may look pretty to some, but it's bad lead dress.

We had a lot of fun at Decca in spite all the mil-spec pickiness, especially when we'd have to work all night to get something out. Pizza on the boss, and sometimes beer if he was in *that* mood. 

mr coffee

[joegagan]

cool post. thanks.

[solderman]

Hi all
I'm just finishing my AD/A flanger. I might just have to wire it like MR COFFEE says cause it sounds like a JET engine and it just might fly like one. And we don't wane have some problems in the air while playing do we

[G. Hoffman]

Reading the NASA workmanship documents (my somewhat weird hobby, from the amount of time I spend doing it these days!), one of the things I found most amusing was the requirement for transparent shrink tubing - again, so the joint underneath it can be inspected.  I've decided I like the look of it too, but that is a whole other thing!

I've got a couple of the anti-wicking heat-sinks, and I really do like them.  My solder joints just seem more flexible, though you DO need to be careful not to birdcage the conductors behind the joint if you need to rework anything. 


Gabriel

[joegagan]

can you explain 'birdcage'?

[DougH]

I'm willing to bet that Doug does better, cleaner work by accident than a lot of guys, just from habit.

Thanks, but I don't do hardware at work. I do low level control software. Used to do VME stuff, now it's going PLC. But I am around the hardware a lot and yes, it's very tidy. But not in the same way as bowtweeky audio gear- tidy in the ways that really count. And it is some crazy stuff - 3" diameter multiconductor cables with potted connectors and so forth.

FWIW, my "hardware" skills with the hobby are pretty average. I've learned over time like everyone else. Some of the early stuff I did was pretty horrible. I just have a pragmatic view of what's important.

[Paul Marossy]

Fender and Matchless amps enjoy great reputations with musicians in general, yet have some of the ugliest wiring you will ever see in an amp. Most musicians never look inside an amp and don't care to. They care about the sound and the reliability, the stuff they see, hear, and deal with outside the amp.

And I might add that when I acquired my 1974 Fender Twin Reverb, it had a loud popping noise when it heated up. The stripboard that the components were on was warped, I guess from years of being cooked inside the chassis. So because the stripboard was warped, there was a broken coupling cap that was arcing, which I understand is usually what causes a loud popping noise in a tube amp. Replaced that capacitor and all was fine.

But all of the "ugly" wiring has held up just fine for 35 years, and the amp doesn't oscillate or anything no matter how loud you make it. My only complaint about it is that it has a lot of hum compared to my other amps. I suppose if it were star grounded instead of all the grounds being soldered directly to the chassis it would be much quieter. Or at least it should have isolated input jacks.

The prettiest wiring job in the universe won't help with those issues. It's very hard to make star grounding look pretty anyway, it's kind of messy by its very nature.

[G. Hoffman]

can you explain 'birdcage'?

Strip a 1/2" of stranded wire, and tin just the very tip.  Now, push the tip of the wire towards the insulation.  The bit behind the tinning will birdcage.


Gabriel

[Guitartoma]

Fender and Matchless amps enjoy great reputations with musicians in general, yet have some of the ugliest wiring you will ever see in an amp.

I dunno - I think this is mighty fine looking... Inside & Out of my Matchless Lightning (They were nice enough to take a couple pictures while they building it! Sweet!)
http://www.flickr.com/photos/22746818@N04/4515466331/in/set-72157623841777984/

[G. Hoffman]

You raise some good points, Gabriel. Leo was very enthusiastic about keeping costs down but only in the context of producing pro-grade instruments. His stuff could have been built cheaper but it wouldn't have met his reliability standards. His approach to "student" amps was just a smaller, simpler version of the big stuff. Look at old Danelectro, Valco, et al for how things might have been.

I don't know that your comparison between Fender and Hiwatt is fair. Both have jacks and capacitors and those parts fail far more often than anything else and both companies used top shelf parts. I've met both Fenders and Hiwatts with failed transformers and both probably in proportion to their market share. The one failure I have seen that is far more common in Fenders and is related to construction practice are failed solder joints. Especially the one resistor that runs lengthwise on the board. This is the area where turret boards are superior to Fender practice. As much prettier as the off-board wiring is on the Hiwatt the only functional improvement on Fender practice might be the buss wire ground on the back of the pots over the grounding plate.

I'm willing to bet that Doug does better, cleaner work by accident than a lot of guys, just from habit.

Define "pro-grade?"  Are we using the standard of a professional orchestra, where every single violin is worth a minimum of $20,000, and most quite a lot more?

I would say that Fender made instruments (in particular, since that is my area of expertise) which were just barely adequate for professional use, most of the time.  Unless of course the bar has a beer cooler or a neon light on the stage circuit!  They skimped on a lot of little things, and in my world (where people are paying over 4,000 for a guitar), that isn't acceptable.  My idea of a "pro-grade" instrument is one where the cavities are all shielded, the finish is perfect, and the hardware doesn't pit the first time someone with acidic sweat looks at it.  Fenders basic designs are spectacularly good, but in production they frequently cut corners.  Of course, I'll never built 1,000 a year, much less a month, so I can afford to nit pick some of those details.  But in Fender's amps, for instance, they have a tendency to be a bit random about things like grounding because it saved them a few dollars per unit, and there is no reason to do so. 

I'd also argue that Fender never used "top-shelf" parts.  They used parts that did the job for a reasonable price.  Particularly Fender.  There were parts available back then with better tolerances and such, but the price:improvement ratio just didn't justify the expense, so they didn't do it.  Again, I don't think they were wrong to work this way - but in my mind "pro-grade" implies something that they weren't.  They were consumer grade products.  When I make stuff in my shop, and when I make stuff for my self at home, I aim to do a bit better than that.  But consumer grade is still pretty damn good, and I think we all owe a lot to consumer grade products - most of the history of Rock & Roll was made on consumer grade instruments! 


Gabriel

[G. Hoffman]

can you explain 'birdcage'?

Strip a 1/2" of stranded wire, and tin just the very tip.  Now, push the tip of the wire towards the insulation.  The bit behind the tinning will birdcage.


Gabriel

HERE'S a link to a NASA workmanship page.  Towards the bottom is a example of birdcaged wire.


Gabriel

[Guitartoma]

G. Hoffman - I just realized who you are! I played some of your & your dad's guitars at the Healdsburg Guitar Festival last year and a very good friend of mine owns one of your dads acoustics - it's his favorite instrument!

And - Love that NASA link - intimidating!!!

[maximee]

While feeling somewhat geeky I'm really enjoying the NASA docs.

http://workmanship.nasa.gov/lib/insp/2%20books/links/sections/601%20General%20Requirements.html
This has great pictures of how good solder joints look vs. bad ones - and how and why to place components one way and not the other...
Thanks for the link!

[Paul Marossy]

Fender and Matchless amps enjoy great reputations with musicians in general, yet have some of the ugliest wiring you will ever see in an amp.

I dunno - I think this is mighty fine looking... Inside & Out of my Matchless Lightning (They were nice enough to take a couple pictures while they building it! Sweet!)
http://www.flickr.com/photos/22746818@N04/4515466331/in/set-72157623841777984/

Their work looks good. The more complex circuits end up looking a little bit messy. The Lightning is pretty simple circuitwise.

Matchless seems to wire their chassis' around where things are physically located on the chassis, and the wiring follows suit. The emphasis is where things are located, which appears to be to minimize noise from transformers, the best location for the tubes, etc. and not to make the wiring pretty. I always thought where they located the tubes on some of their models was kind of odd compared to Fender for example, which has them all in a row.

[joegagan]

a soon as my lovely kalena gets home i will make sure she reads this entire thread (looks at all the pictures and links too)

i will ask her if it is sexy. will get back to you guys on that.

[Paul Marossy]

a soon as my lovely kalena gets home i will make sure she reads this entire thread (looks at all the pictures and links too)

i will ask her if it is sexy. will get back to you guys on that.

I bet that I can accurately predict the answer on that one!