questions for someone with knowledge on electronics... GROCK

thejoe · Unread post by **thejoe** » Wed Jun 30, 2004 8:28 pm

so i broke the electronics on my acoustic today

the solders cracked on the xlr and 1/4 in. outs

anyway... the cord coming out of the pickup goes to the eq thing on the top of the guitar... then out from there it goes through a big grey cord to the xlr and 1/4 in. outs on the bottom of the guitar.. but the battery cords going to the eq also go through this cord

now.. can i just solder the little cord coming out of the pickup right to a 1/4 inch jack and use that?... or to an xlr jack?

can i use the grey cord and solder that to a 1/4 inch or xlr jack?

as you can see.. i need some advice...

if is do any of those things.. would i need a di?

im pretty clueless

please help mr. grock or anyone for that matter

Brock · Unread post by **Brock** » Wed Jun 30, 2004 9:56 pm

taylor?

thejoe · Unread post by **thejoe** » Wed Jun 30, 2004 10:19 pm

martin

just a peizo under bridge pickup

grock · Unread post by **grock** » Thu Jul 01, 2004 11:39 am

Pictures would help but i'm gonna give this a shot cuz i like you.

crash_in_to_me wrote:so i broke the electronics on my acoustic today

the solders cracked on the xlr and 1/4 in. outs

my first thought is "why don't you just resolder what has cracked?"

crash_in_to_me wrote: anyway... the cord coming out of the pickup goes to the eq thing on the top of the guitar... then out from there it goes through a big grey cord to the xlr and 1/4 in. outs on the bottom of the guitar.. but the battery cords going to the eq also go through this cord

this sounds like a normal setup where the piezo goes to the pre-amp and the preamp sends the signal to the output.

crash_in_to_me wrote: now.. can i just solder the little cord coming out of the pickup right to a 1/4 inch jack and use that?... or to an xlr jack?

i've never tried to use a pickup designed for use with a pre-amp and then bypassing that pre-amp. my guess is that with the low signal strength that a piezo puts out, you are gonna have significant signal loss. but i don't know that for sure. cuz it seems that any passive pickup would run into this problem but that's obviously not true. if you do bypass the pre-amp, you would need a preamp before any effects, but you could always use the effects loop in your amp. a DI is not necessary. you could always wire it up and see! (just make sure you get the grounds right cuz if you do it wrong you could burn out your amp and any effects in your chain). based on your description of the problem i still don't see why you can't just resolder what cracked.

crash_in_to_me wrote: can i use the grey cord and solder that to a 1/4 inch or xlr jack?

yeah just solder what broke off back to where it goes!

If you got more descriptions or pics then maybe i could see why you are pursueing other options.

Word up.

thejoe · Unread post by **thejoe** » Thu Jul 01, 2004 12:19 pm

i tried resoldering what cracked and i kinda messed it up because its way too small to resolder and its old and yeah.. i screwed it up

ok soo

ive pretty much come to the conclusion that that grey cord coming out from the preamp is just split into two outputs => 1/4 in. and xlr
the solders on both jacks are cracked off this green thing with a bunch of wires going into it... and again, i cant resolder them back on because the connections are way too small and i can barely see them

now.. im wondering if i can just take the signal going out from the preamp and solder that right to the 1/4 in. out or xlr.... how would i do this for the xlr?
if i soldered it to the xlr i wouldnt need a di, right?
ir i soldered it to the 1/4 in. would i want a di?

thanks for the help
i know this is probably coming off very confusing
i will try to get a picture up
thanks

grock · Unread post by **grock** » Thu Jul 01, 2004 12:52 pm

crash_in_to_me wrote:i tried resoldering what cracked and i kinda messed it up because its way too small to resolder and its old and yeah.. i screwed it up

ok soo

ive pretty much come to the conclusion that that grey cord coming out from the preamp is just split into two outputs => 1/4 in. and xlr
the solders on both jacks are cracked off this green thing with a bunch of wires going into it... and again, i cant resolder them back on because the connections are way too small and i can barely see them

now.. im wondering if i can just take the signal going out from the preamp and solder that right to the 1/4 in. out or xlr.... how would i do this for the xlr?
if i soldered it to the xlr i wouldnt need a di, right?
ir i soldered it to the 1/4 in. would i want a di?

thanks for the help
i know this is probably coming off very confusing
i will try to get a picture up
thanks

i really think you might be in "bring it to a tech" land.

If it's too small to solder then that's your best bet. but if you think it is do able to solder the pickup sstraight to the output, then i'm all for trying that.

you might look for your pick-up on the internet to try and find some wiring schematics before you delve in too deep.

you don't need a DI at all. What you may want is some kind of external pre-amp which is basically exactly what is in the guitar but in a pedal form. many amps have a pre-amp integrated in so this may not be necessary either. A DI is something very different. Direct boxes are often referred to as "DI" boxes. This stands for "Direct Injection" as their main purpose is to convert unbalanced and/or high impedance instrument signals into a format suitable for direct connection to a mixing console - without the use of a microphone. are you hooking this up to a mixing console? probably not. and if you are playing a show most modern places have DI boxes or their mixing boards can take a direct guitar signal.

thejoe · Unread post by **thejoe** » Thu Jul 01, 2004 1:07 pm

hope that helps

ok thanks..

umm i realy dont want to take this to the shop because im strapped for cash right now

im still thinking i can just take the signal fromthe preamp and solder it right to the 1/4 in. out... if youknow if this will work.. please let me know

and yeah i always plug it right into the mixer and the place where i play has just a regular powered mixer.. no dis so im thinking i need one

sorry for taking all this time
thanks again[/img]

thejoe · Unread post by **thejoe** » Thu Jul 01, 2004 1:09 pm

there is the 1/4 in. out (which also has its connections broken) also soldered to that plastic thing on the other side

grock · Unread post by **grock** » Thu Jul 01, 2004 4:12 pm

Yikes. yeah there doesn't look to be much hope for that circuit board.

ok, soldering up the jack to the pickup should work. but i really don't know how you would go about doing that. so i'm of little help to you there. do you normally just plug 1/4" from guitar to the mixing board. cuz you don't need a DI for that. the DI takes a 1/4" and turns it into a signal that can be sent with XLR. and most mixing boards can take straight 1/4" that i've been in contact with.

XLR is sometimes prefered when there are long cable runs like from a stage around the room and into a mixing console in the back. A normal unsheilded guitar chord would pick up a lot of noise. it's like a huge antenna.

i'm not sure you can justify buying a DI (other than a cheap one) when you could save the money and get the guitar fixed. i got a Sansamp Acoustic DI that i use to head an effects loop and had to buy a special chord to go XLR to 1/4" to use with my amp. and i haven't actually used it as a DI box yet cuz when i play i normally just hand the guy a chord and he plugs it into a extension from the Mixing Console, and not a DI. maybe i'll ask whats up with that next time i play.

thejoe · Unread post by **thejoe** » Thu Jul 01, 2004 6:55 pm

ok dude thanks for your help

i got it working

i figured how to take that big ugly thing apart so i could get at it more easily and i got the xlr out resoldered

but.. now it kind of hisses and pops... its not loud at all but its still not good... i think its just from leaving some wires exposed when i resoldered it because before they were all sheilded inside that grey thing
so im gonna go backin there and electrical tape them up and see what happens.. who knows

ok so.. i was under the impression that a di box is used to change an unbalanced signal (ie 1/4in. guitar cable) to a balanced signal (mic cable)

is that right?

but now that i fixed the xlr out i shouldnt need the di box anymore

and umm... what exactly do low and high impedence mean?... just low and high power? or am i way off

thanks for your time dude

grock · Unread post by **grock** » Fri Jul 02, 2004 4:34 pm

crash_in_to_me wrote:ok dude thanks for your help

i got it working

i figured how to take that big ugly thing apart so i could get at it more easily and i got the xlr out resoldered

but.. now it kind of hisses and pops... its not loud at all but its still not good... i think its just from leaving some wires exposed when i resoldered it because before they were all sheilded inside that grey thing
so im gonna go backin there and electrical tape them up and see what happens.. who knows

ok so.. i was under the impression that a di box is used to change an unbalanced signal (ie 1/4in. guitar cable) to a balanced signal (mic cable)

is that right?

but now that i fixed the xlr out i shouldnt need the di box anymore

and umm... what exactly do low and high impedence mean?... just low and high power? or am i way off

thanks for your time dude

that is what a DI box does. turns unbalanced into a balanced signal (of course it is more complicated than that but you get the gist).

power is more like volts. impedance is another boat. i don't understand it really and many many many websites are out there to try and explain it. you could read an entire book and still only kinda understand impedance.

thejoe · Unread post by **thejoe** » Fri Jul 02, 2004 10:07 pm

alright thanks soooo much for your help

because i was about to take it in but then i remembered that you said to try soldering what broke off.. so i gave it another look and i got it to work

thanks

geekmug · Unread post by **geekmug** » Tue Jul 06, 2004 5:52 am

impedance is a hard thing to explain.. the simplest explaination is the it is the AC analog of DC resistance. Ohm's law for DC is V = IR, or R = V/I. The impedance version is exactly the same, Z = V/I.

The only real important thing to know is that you make input impedances large compared to the output impedances of whatever the signal source is, and make output impedances tiny compared to the load it's driving. Doing so makes the signal travel in the correct direction without fighting against a load (would appear as either signal leakage or noise).

On some equipment, if you max the amplifier gain for an input and lower the source's gain, cause this "phenomena". If you have ever taken a pair of headphones and spoke into the earpiece and had it appear on the signal, this is that. It's hard to universally create a demonstration, sorry.

In reference to 1/4" and XLR cable runs.. 1/4" is usually called a "High-Z" cable and an XLR a "Low-Z" cable, and this simply refers to the kind of loading it produces. The implications of this are not worth going into and are contradictary in many ways, so I'll leave it at that.

Impedance is also the phenomena used to create high-pass (capacitors) and low-pass (inductors) filters.. an example would be the capacitors you see on the tone controls of an electric guitar; the variable resistance (knob) adjusts the R value and the capacitor provides a fixed X, allowing you to tweak the high-pass filters (the frequency and curve will both change depending on the resistance).

Boredom reigns.

thejoe · Unread post by **thejoe** » Tue Jul 06, 2004 12:12 pm

oh wow

is the "z" in low z and high z the same as in your little equation with Z=V/I?

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questions for someone with knowledge on electronics... GROCK

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