The reason for negative tip jacks?

[aron]

I forget the reason why most pedals are negative tip. R.G., I went out and bought a One Spot and the 5 tip extender. Then I found out that it was center/tip negative. Radio shack was out of tips etc..... I ended up kludging a connector. It seems "natural" to have the body of the power jack grounded and not isolated, but I figure there's a good reason.

[rockgardenlove]

Maybe it's because those barrel style plugs first came up when most transistors were still PNP?  Not necessarily with guitar pedals, just in general.  When did the wallwart come into usage?

No clue.  Good question.

[aron]

There was a valid reason, but I can't think of it. If the tip were positive and the barrel negative, then if the barrel ever touched any jack etc... it would be ok right? But if the barrel is positive and it touches a jack or enclosure it will cause a short. hmmm........

I did get my "small" pedalboard working with a Shaka overdrive at the front and a bunch of mini Danelectro pedals wired with a Korg Dynamic echo at the end. I might switch to the Echo Park.

[Auke Haarsma]

slighty OT: The Echo Park doesn't like to be chained, best to use a separate adapter for it. It's know th cause hum when in a daisychain.

[puretube]

it`s a vintage reason and a stupid practice, IMHO:

those first (western world) stompboxes used PNP germanium - a good reason to have the positive pole of the jack grounded...

The Japanese invasion came with "borrowed" technology, and flooded the market...

...and kept the so-called "standard" polarity that they spreaded,
even after the technology for the overwhelming part of the pedals
had become NPN-based, with negative ground.

So, now they needed to use isolated jacks, because they prematurely had created a "standard"
which nowadays completely is outdated... 


And almost all the other manufacturers followed...

[Mark Hammer]

I am uncomfortable disagreeing with someone whose knowledge I respect so much, but.....NO.

The reason is simple.  Whenever a plug has to perform a switching function, it has to physically move a contact upon insertion.  Generally, this involves bumping against a spring-leaf type connector such that a default connection is disrupted and replaced with another.  With phone plugs, there is really no other choice than to use the tip of the plug to perform that action, so phone plug adaptors are close to 100% tip-positive. It IS possible for a switching function to be performed by bumping against something plastic which doesn't have to involve the actual polarity of the contact doing the bumping (e.g., some jacks used for replacing external speakers with headphones), but those jacks are bigger and bulkier, and more expensive.

In the case of barrel connectors, the outside of the plug is the part that does the "bumping" to switch between internal battery and alternate power source.  So, tip-negative, shaft-positive.  I suppose one *could* design a barrel jack where the "bumping" is done by forward motion rather than lateral motion, but my guess is that it is a little late in the game and would probably be too pricey.

HOWEVER.....

Having an exposed shaft as positive poses a greater safety risk to the handler than shaft-ground as near as I can tell (with AC it doesn't matter...they're both dangerous).  Assuming the handler touches the exposed shaft of the plug and a ground surface, or bumps/grazes the exposed shaft against a ground connection, there is the risk of current passing.

SO....

When there is no need to have the barrel plug disable an internal battery, it becomes the supplier's perogative to have outside be positive or ground.  If it is their choice, then many will opt for the safer route, which is tip-pos (less exposed area to touch) and shaft-ground.

True, there are plenty of instances where manufacturers choose to retain the tip-neg/shaft-pos convention in their gear even when there is no internal battery to disable.  But I suspect that stems more from their expectation that many of their end-users would already have adaptors sitting around from other gear that use the tip-neg convention and confusion with any other system would invite another sort of safety risk, so they choose to go with what they figure the user already knows and owns.

Plausible?

[gez]

In the case of barrel connectors, the outside of the plug is the part that does the "bumping" to switch between internal battery and alternate power source.  So, tip-negative, shaft-positive.  I suppose one *could* design a barrel jack where the "bumping" is done by forward motion rather than lateral motion, but my guess is that it is a little late in the game and would probably be too pricey.

If that were the case Mark, then all you'd have to do is wire things so that the -ve battery connection is disconnected (doesn't matter which wire goes, so long as the circuit is broken).  This would allow use of a -ve barrel.  Unless I've missed something?

[The Tone God]

http://www.diystompboxes.com/smfforum/index.php?topic=33606.0

Andrew

[R.G.]

It's that Boss thing. Whomever is first when something catches on becomes the standard because it's so expensive to change it.

We have this legacy in:
Power line frequency - it was hard to generate high frequencies, so we stayed low. Some early systems were 25 Hz. Thankfully those died out. 400Hz as in airplanes is better. All electrical power equipment gets between 1/6 and 1/7 as much iron because of the higher frequency. George Westinghouse used 60Hz.
Computer keyboards - remember Dvorak? Clearly better. Schoales won, though.
Railway gauge - this one is kinda fun. I don't know if this is literally true, but it has that ring of authenticity about it.
American railway rails are set exactly that far apart because we first imported rail cars from England. English railway cars are built with the wheels that far apart because they were first made by horse and oxcart makers. Horse and oxcart makers made them that wide because they fit the roads. The roads were that wide because the first roads were built by the Romans in England, and any cart that didn't fit the Roman roads at least moderately was not usable on the best roads. The Romans made the roads that width because it was the width that fit all of their chariots and baggage wagons. The chariots and baggage wagons were that wide because... yep, you're about to get it...




That's the width it takes to have two horses' behinds working side by side without interference between the width of the wheels.

We may glean two things from this. (1) Railroads are that wide because God Said So when he made horses and (2) never doubt the power of a horse's ass to affect things longer and all out of proportion to their real utility.

[aron]

Thanks everyone.

OK, here's the small pedal board config:

Shaka Overdrive->Dano French Toast (foxx tone machine)->Dano Chili Dog (Octave down)->Dano Chicken Salad (phaser)->Line 6 Echo Park.

If it wasn't for the Echo park, this thing would be much lighter. I didn't have any problem with HUM using the One Spot for all pedals including the Echo Park.

That being said, what is the type of barrel connector (isolated) that I should start carrying (since I want them myself)? 2.1MM, but what brand. What's the easiest to work with?

Thanks!

[aron]

Of course I have to ask the obvious.... is there a plug that will swap the polarity made by visual sound? I suppose that would be the easy answer!

[Mark Hammer]

If it wasn't for the Echo park, this thing would be much lighter. I didn't have any problem with HUM using the One Spot for all pedals including the Echo Park.

Wait until Behringer comes out with their EP clone this summer and if the noise isn't too bad, buy one of those.  That ought to save you 2lbs of pedalboard!

[MKB]

Not sure why Boss did it that way, but I bet there was some sort of standard power adapter available at that time with the ring positive.  Boss just used a standard part they found with the polarity the way it was available.  I can't imagine any other real compelling reason to do it that way, especially as it is such a pain to use; back then you had to cut a square hole in your case to get a secure jack installed as the isolated threaded round ones weren't available yet.

The main reason for the barrel connector (my apologies if this has been mentioned) might be because the 1/8" phone plug connector can short out as it is plugged in.  Also, if the plug is pulled out partway, you short out the supply.  The barrel connector can't do that.

It's that Boss thing. Whomever is first when something catches on becomes the standard because it's so expensive to change it.

We have this legacy in:
Power line frequency - it was hard to generate high frequencies, so we stayed low. Some early systems were 25 Hz. Thankfully those died out. 400Hz as in airplanes is better. All electrical power equipment gets between 1/6 and 1/7 as much iron because of the higher frequency. George Westinghouse used 60Hz.
Computer keyboards - remember Dvorak? Clearly better. Schoales won, though.
Railway gauge - this one is kinda fun. I don't know if this is literally true, but it has that ring of authenticity about it.
American railway rails are set exactly that far apart because we first imported rail cars from England. English railway cars are built with the wheels that far apart because they were first made by horse and oxcart makers. Horse and oxcart makers made them that wide because they fit the roads. The roads were that wide because the first roads were built by the Romans in England, and any cart that didn't fit the Roman roads at least moderately was not usable on the best roads. The Romans made the roads that width because it was the width that fit all of their chariots and baggage wagons. The chariots and baggage wagons were that wide because... yep, you're about to get it...




That's the width it takes to have two horses' behinds working side by side without interference between the width of the wheels.

We may glean two things from this. (1) Railroads are that wide because God Said So when he made horses and (2) never doubt the power of a horse's ass to affect things longer and all out of proportion to their real utility.

Bringing the horses' ass into the rocket age...  I read the German V2 rocket size was determined by if it could be shipped via rail.  It had to fit through all the rail tunnels as well as be able to go around the turns in the rail bed.  If it was too long or fat it couldn't be shipped by rail.

[aron]

>Wait until Behringer comes out with their EP clone this summer and if the noise isn't too bad, buy one of those.  That ought to save you 2lbs of pedalboard!

Interesting.

Well, the Echo park sounds great. Not a memory man by far, but one of the best digital delays I have heard and it's fun!

[puretube]

IMHO: If "Beeringer" would start tomorrow with issuing (logically more correct) pin positive equipped pedals
(like proposed to a well known manufacturer for their new small boxes by a small designer...  ),
there probably would be a 180° design standard shift on the whole market within 2 or 3 years...

But those freeriders seem to copy everything - even what they seem to regard as "standards"...

(Yes: I don`t intend to wanna discuss whether 1/4" jacks or barrels are preferable - that`s another story - just the polarity issue).

[EDIT] this was the reply to reply#8 by R.G., without having seen the followups...

[puretube]

Bringing the horses' ass into the rocket age...  I read the German V2 rocket size was determined by if it could be shipped via rail.  It had to fit through all the rail tunnels as well as be able to go around the turns in the rail bed.  If it was too long or fat it couldn't be shipped by rail.

any of you know why the size of the hole in a CD is the size it is?
(there are at least 3 persons here, that know the answer... )

[R.G.]

Of course I have to ask the obvious.... is there a plug that will swap the polarity made by visual sound?Huh I suppose that would be the easy answer

As it happens, yes, there is. It's the obvious thing - it just has a receptacle and a plug, with the wires inverted between them. It doesn't help with the old positive ground shorting negative ground, but it does invert the voltage polarity on the end of the wires.

[Processaurus]

I guess its my turn to respectfully disagree with the sharp minds here about how the standard came to be.  Boss uses an interesting and simple way of avoiding ground loops and wrong polarity protection with their power supply and daisy chain system, that's by putting a Si diode and small value resistor in series with the chassis and circuit ground and the tip connection on the 2.1mm jack inside each and every pedal.  They needed to isolate the PS (-) from the chassis.  The battery ground is connected to the circuit by the old stereo jack trick, so it has to be connected directly to the chassis/circuit ground.  Also they didn't want the series voltage drop from the diode and resistor when you were using just the battery.  So since they can only switch the barrel connection on the jack to disconnect the battery, and they didn't want to connect the battery ground along the same path the power supply ground was (through the Si diode and resistor, which would drop the battery voltage seen by the circuit unacceptably), they had no choice but to use the barrel switch to disconnect the + from the battery to the circuit.

With their simple ground loop avoiding + polarity protection system they didn't have a choice (about the polarity or about using an alternative to the 1/8" phono plug like DOD uses).  What's funny is the inferior standard of the tip negative (from the viewpoint of daisy chains shorting out on stuff) was adopted by companies that make no use of Boss's original idea, that require two horses to fit side by side inside that jack.

[widdly]

Bringing the horses' ass into the rocket age...  I read the German V2 rocket size was determined by if it could be shipped via rail.  It had to fit through all the rail tunnels as well as be able to go around the turns in the rail bed.  If it was too long or fat it couldn't be shipped by rail.

any of you know why the size of the hole in a CD is the size it is?
(there are at least 3 persons here, that know the answer... )

Heh I heard that story once.  Some engineers where sitting around in a hazy cafe in Amsterdam and they got a Heineken beer coaster and put a ten cent piece in the middle and traced around it and said "let's make tiny little records that are shiney".

[aron]

http://en.wikipedia.org/wiki/User_talk:Dsc