Basic Cabling Question for Home Recording Studio

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Greetings, all:

My apologies if this newsgroup is too high-powered for a novice
question about home recording; I surfed around trying to find a more
appropriate forum for beginners, without much success. If anybody
knows a great place for home recording newbies like myself to compare
notes, I'd welcome any suggestions!

What I'm dealing with right now is a question of cabling. All I'm
trying to do is record some simple tunes using a Shure SM58 and a
Guild electric/acoustic guitar. I'm trying to run both the vocals and
guitar through a Behringer UB802 mixer and into my sound card.

Unfortunately, when I use my existing 1/4" cables, I'm getting a
pretty good hum coming through the system. Oddly, however, the moment
I physically touch the side of one of the plugs on these cables the
hum practically disappears. Is this a grounding issue of some kind?
Or a sign of a vastly inferior or damaged cable? It's gotten to where
I have to awkwardly hold my foot up and wrap my toes around the input
plug while I play if I want to get a decent sound; hardly an optimal
arrangement!

So I'm wondering a couple of things. First of all, would using an
XLR-to-XLR connection from my microphone produce a better sound,
instead of the XLR-to-1/4" connector I use now? Secondly, should I
buy a premium 1/4"-to-1/4" cable for my guitar as a likely resolution
to the "humming" problem? And should this be of the "balanced" or
"unbalanced" variety?

Any help or tips would be greatly appreciated!

 

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Matt from Seattle wrote:
> Unfortunately, when I use my existing 1/4" cables, I'm getting a
> pretty good hum coming through the system. Oddly, however, the moment
> I physically touch the side of one of the plugs on these cables the
> hum practically disappears. Is this a grounding issue of some kind?
> Or a sign of a vastly inferior or damaged cable? It's gotten to where
> I have to awkwardly hold my foot up and wrap my toes around the input
> plug while I play if I want to get a decent sound; hardly an optimal
> arrangement!
>
> So I'm wondering a couple of things. First of all, would using an
> XLR-to-XLR connection from my microphone produce a better sound,
> instead of the XLR-to-1/4" connector I use now? Secondly, should I
> buy a premium 1/4"-to-1/4" cable for my guitar as a likely resolution
> to the "humming" problem? And should this be of the "balanced" or
> "unbalanced" variety?

First thing you should do is turn down everything but the microphone
and see if the hum is still there. Second thing you should do is turn
down everything but the guitar and see if the hum is still there.

Most likely it's your guitar, but that's not for sure.

As for cabling, unless the cable is defective, replacing your 1/4"
to 1/4" instrument cable with a higher-quality one isn't going to
make any difference as far as hum goes, as long as they are of the
same basic construction (and 1/4" instrument cables are pretty
simple).

As for the microphone, your XLR-to-1/4" cable is probably not
balanced. It is possible to build a 1/4" cable that carries a
balanced signal[1], but it is not usually done that way with
microphones and anyway I don't think most mixers' 1/4" channel
inputs are balanced inputs. Anyway, balanced is generally
better in that if there is noise external to the cable, the
balanced circuit will reject it. (In a balanced circuit, the
microphone or other sound source produces two signals that
are identical except for being opposite voltage, i.e. basically
one is positive when the other's negative. The input on the
mixer or whatever then presents two identical loads, one to
each "leg", and it reverses one of the two signals before it
adds them together. Since the two wires carrying opposite
signals run alongside each other, they pick up virtually the
same noise, and the balanced input cancels the noise out when
it inverts and adds.) So, balanced doesn't really sound
"better", but the one thing it does do is that it rejects noise
that might be picked up by the *cabling*.

Aaaanyway, not having a balanced cable on your microphone is
probably not the source of your hum. So it would be a good
idea to go with a balanced cable (which typically means XLR
on both ends), but it's unlikely to eliminate your hum problem.

If I were you, I'd do some experimentation. If you can borrow
other cables from a friend, that would be a good idea. You might
also want to make sure your equipment (particularly your mixer)
is plugged into a properly-grounded outlet. Also, listen to
your mixer's output with headphones or something when it's not
connected to your sound card.

- Logan

[1] The 1/4" phone plug will then have three contacts instead of
two on it. That's commonly called TRS, for Tip, Ring, and
Sleeve, which are the names of the three different contacts.

 

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>
>So I'm wondering a couple of things. First of all, would using an
>XLR-to-XLR connection from my microphone produce a better sound,
>instead of the XLR-to-1/4" connector I use now? Secondly, should I
>buy a premium 1/4"-to-1/4" cable for my guitar as a likely resolution
>to the "humming" problem? And should this be of the "balanced" or
>"unbalanced" variety?
>

You have two XLR microphone inputs on your Behringer. Use them.

The hum is almost certainly your guitar. Does it occur when the
guitar is NOT plugged in to the mixer? You need a correctly wired
undamaged lead. You don't need an expensive one. The output isn't
balanced, so a balanced cable is unnecessary.

What sort of guitar? What pickup?

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"Possibly the world's least impressive web site": George Perfect

 

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"Matt from Seattle"

>
> What I'm dealing with right now is a question of cabling. All I'm
> trying to do is record some simple tunes using a Shure SM58 and a
> Guild electric/acoustic guitar. I'm trying to run both the vocals and
> guitar through a Behringer UB802 mixer and into my sound card.
>
> Unfortunately, when I use my existing 1/4" cables, I'm getting a
> pretty good hum coming through the system. Oddly, however, the moment
> I physically touch the side of one of the plugs on these cables the
> hum practically disappears. Is this a grounding issue of some kind?


** The guitar is the problem - likely the bridge is not wired to the
earth of the electrics. It is essential that the strings of the guitar are
wired to ground - so that when you play the strings earth YOU.

Is the guitar a steel string acoustic with some kind of bug pickup fitted ?

If so, hum is a common problem.



> So I'm wondering a couple of things. First of all, would using an
> XLR-to-XLR connection from my microphone produce a better sound,

** No.

> Secondly, should I buy a premium 1/4"-to-1/4" cable for my guitar as a
likely resolution
> to the "humming" problem?


** No.

And should this be of the "balanced" or
> "unbalanced" variety?


** All guitar leads are unbalanced.




......... Phil

 

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Laurence Payne <l@laurenceDELETEpayne.freeserve.co.uk> wrote in message news:<gmm2k0t4dld3ll26cidic3pk0eapcd77s1@4ax.com>...

> You have two XLR microphone inputs on your Behringer. Use them.

Sounds like that's the consensus on the microphone inputs; I'll switch
to a pure XLR setup, just for the improved connection mechanism even
if I can't tell a major difference in the sound quality.

> The hum is almost certainly your guitar. Does it occur when the
> guitar is NOT plugged in to the mixer? You need a correctly wired
> undamaged lead. You don't need an expensive one. The output isn't
> balanced, so a balanced cable is unnecessary.
>
> What sort of guitar? What pickup?

I have narrowed the hum down to the guitar, as you suspected. It hums
not only when I go though the mixer, but also when just plugged in
directly to my amp using a single 1/4" cable. And still, as soon as I
touch one of the plugs, the hum virtually disappears. The model of
the guitar is a Guild F4CE-NTHR and I'm simply using the built-in
pickup that came originally with the guitar when I bought it. I don't
any specific make or model information on the pickup unit that I can
pass along. I did try switching cables, however, just to make sure
that wasn't the problem, and I got the same hum with another "known
good" cable.

So assuming it's some malfunction with the guitar, is there anything I
might be able to do to fix it or is this a job for the repair shop?
I've had the guitar for years, and barely used it, so I'd be surprised
if there was actual damage to the instrument in any way.

Any further suggestions would be appreciated -- you (and your
colleagues) on this board has already been a great help in diagnosing
the problem...

 

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Matt from Seattle wrote:

> Greetings, all:

[snip]

> appropriate forum for beginners, without much success. If anybody
> knows a great place for home recording newbies like myself to compare
> notes, I'd welcome any suggestions!

Sounds like a description of alt.music.home-studio. It's on google. See
you there 🙂

--
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np:
http/www.unmusic.co.uk
http/www.unmusic.co.uk/Top_50_Films.html - favorite films
http/www.unmusic.co.uk/amh-s.html - alt.music.home-studio

 

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Matt from Seattle wrote:
> I have narrowed the hum down to the guitar, as you suspected. It hums
> not only when I go though the mixer, but also when just plugged in
> directly to my amp using a single 1/4" cable. And still, as soon as I
> touch one of the plugs, the hum virtually disappears. The model of
> the guitar is a Guild F4CE-NTHR and I'm simply using the built-in
> pickup that came originally with the guitar when I bought it. I don't
> any specific make or model information on the pickup unit that I can
> pass along. I did try switching cables, however, just to make sure
> that wasn't the problem, and I got the same hum with another "known
> good" cable.
>
> So assuming it's some malfunction with the guitar, is there anything I
> might be able to do to fix it or is this a job for the repair shop?
> I've had the guitar for years, and barely used it, so I'd be surprised
> if there was actual damage to the instrument in any way.

Well, as luck would have it, I have a 9 or 10 year old Guild F4CE-NT,
so I just tried it with my cheap Epiphone practice bass amp and a
cheap Guitar Center cable I have that I would guess is maybe 15 or 20
feet long. Cranked everything up as much as I could (having to
vigorously mute the strings to avoid feedback, actually), and basically
no hum. Well, there is just a little, but that occurs even if I have
nothing plugged into the amp's input. As I said, it's a cheap amp.

However, then I got one of those two-prong to three-prong adapters
that one uses if one wants to avoid proper grounding. Mine conveniently
has the ground screw tab thing broken off so I am assured of no
connection. I plugged the bass amp into the wall with that thing.
With it, I get a noticeable hum. Not atrocious, but still definitely
there.

So I guess the only information I have is that a Guild F4CE guitar
shouldn't normally have a hum problem. That doesn't necessarily mean
your guitar's pickup is bad. Have you checked to ensure you have a
good ground on the outlet your mixer is plugged into? You could
try moving the mixer to a different outlet or a different circuit,
or even a different house if that's convenient.

Another totally different idea is to just not record with the built-in
pickup. Pickups usually sound OK but not great. Supposedly these
days you can buy basically decent condenser mics for pretty cheap,
so you might be able to get a cheap instrument mic and just use that.

- Logan

 

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(snip)

> So I guess the only information I have is that a Guild F4CE guitar
> shouldn't normally have a hum problem. That doesn't necessarily mean
> your guitar's pickup is bad. Have you checked to ensure you have a
> good ground on the outlet your mixer is plugged into? You could
> try moving the mixer to a different outlet or a different circuit,
> or even a different house if that's convenient.

Thanks for all of your advice, Logan and Phil.

Having tried the guitar in another outlet, and still gotten the hum,
it sounds like Phil's original diagnosis of the strings not being
"earthed" is likely the source of the problem. At this stage, since
I'm not very handy about these types of electrical issues -- and am
not really sure what "earthed" means, even -- I'll have to take the
unit into a guitar store and see if they can make the needed
adjustments.

I've thought about using a condenser mike to record some guitar
tracks, instead of an actual pickup, but the pickup setup is obviously
a lot more convenient and I don't have the $$$ for a decent condenser.
I'd also prefer to have a fully functional guitar since it's a pretty
nice instrument and it would bother me knowing that it's got an
internal malfunction.

If you have any other final thoughts, pass 'em along. Otherwise, I'll
probably be hitting the repair shop in a couple of days...

 

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Logan Shaw wrote:

> Phil Allison wrote:
>
> > "Logan Shaw"
> >
> >>Are the strings normally grounded on acoustic guitars with pickups?
>
> > ** Yes - it is standard practice on all electric guitars.
>
> Doesn't that seem like a red herring since we are talking about
> an acoustic guitar and not an electric?

The OP referred to his guitar as a "Guild electric/acoustic guitar".

I assume that means an electric guitar with a voice box rather than a solid
body type - and *not* an acoustic guitar with an added pickup.

< snip >

> Actually, the hum goes away when the OP touches the connector on the
> cable (or the mixer? some connector...). It has not yet been verified
> that this connector is actually connected to any ground.

If nothing else ( e.g. with Class II isolated equipment ) , it's connected
to 'electronics ground'.

This is the clue.

If the guitarist is grounded the problem goes away.


Graham

 

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Logan Shaw wrote:

> However, then I got one of those two-prong to three-prong adapters
> that one uses if one wants to avoid proper grounding. Mine conveniently
> has the ground screw tab thing broken off so I am assured of no
> connection.

Do you have good life insurance ? Do your gigging friends have good life
insurance ?

The ground connection isn't there just to look pretty ( nor to be snapped
off ).

If you read the manual or back panel - expect to see a notice saying
something like "this equipment must be grounded".

There's a good reason for that.


Graham.

p.s. some equipment doesn't need grounding - but instead has to be
manufactured to much higher levels of shock protection and insulation to
meet safety regulations - don't assume all gear is the same.

Lifting an earth ( especially cutting a ground lug ) to cure hum is a sure
sign of possible trouble coming your way.

 

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Pooh Bear wrote:
> Logan Shaw wrote:
>>Phil Allison wrote:
>>>"Logan Shaw"

>>>>Are the strings normally grounded on acoustic guitars with pickups?

>>> ** Yes - it is standard practice on all electric guitars.

>>Doesn't that seem like a red herring since we are talking about
>>an acoustic guitar and not an electric?

> The OP referred to his guitar as a "Guild electric/acoustic guitar".
>
> I assume that means an electric guitar with a voice box rather than a solid
> body type - and *not* an acoustic guitar with an added pickup.

Just to clear things up, here are some photos of a Guild F4CE:

http/home.austin.rr.com/logan/guild-f4ce/

Unfortunately, it's just about impossible to see inside to tell what
the pickup is like. All I can tell is that it there is a relatively
thick (compared to the super-thin one that goes to the 1/4" output
plug) cable headed towards the bridge. It's probably more than two
conductors based on thickness. I can't see anything more because
the X-brace blocks the view.

- Logan

 

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Pooh Bear wrote:
> Logan Shaw wrote:

>>However, then I got one of those two-prong to three-prong adapters
>>that one uses if one wants to avoid proper grounding. Mine conveniently
>>has the ground screw tab thing broken off so I am assured of no
>>connection.

> Do you have good life insurance ? Do your gigging friends have good life
> insurance ?

This is not the kind of amp you'd take to a gig. ;-)

But no need to worry: I just plugged the amp into the adapter thing
for a few short moments to test out whether that had an effect on the
sound. For the past ten years or so, that little ground-cheating
adapter thingy has sat in my "box of random electronic crud" that I
keep under the bed.

> Lifting an earth ( especially cutting a ground lug ) to cure hum is a sure
> sign of possible trouble coming your way.

Actually, I was using this little adapter dealy to test whether there
would be more hum if the amp was not properly grounded, and sure enough,
there was more hum that way.

- Logan

 

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In article <rPS0d.14552$ug2.2166@fe2.texas.rr.com> lshaw-usenet@austin.rr.com writes:

> Just to clear things up, here are some photos of a Guild F4CE:

It certainly looks like an acoustic guitar with no metal to connect to
the strings unless there's a metal plate under the bridge that the
ball ends contact. Doubt it.

I'd look at the part of the system between the wire coming from the
pickup and the amplifier input stage. There are a lot of possibilites
there, and having another guitar, another amplifier, and a known good
(well shielded, properly wired, and not broken) cable to substitute
one at a time would be a good troubleshooting approach.



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However, until the spam goes away or Hell freezes over,
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"Logan Shaw"
Phil Allison wrote:

> >>
> >>Are the strings normally grounded on acoustic guitars with pickups?
>
> > ** Yes - it is standard practice on all electric guitars.
>
> Doesn't that seem like a red herring since we are talking about
> an acoustic guitar and not an electric?


** Bullshit - it is an "electric" guitar.

It has a pickup - it is being used with an amplifier - so it is an
electric guitar.



> Anyway, my point is that neither a guitar shop nor he nor anyone else
> can fix the guitar, because the guitar is not broken. It is working
> as designed.


** The OP's one hums, that is a fixable fault - you imbecile.


>
> > ** Did you read the OP at all ????
> >
> > The hum goes away when the OP touches ground !!!!!
>
> Actually, the hum goes away when the OP touches the connector on the
> cable (or the mixer? some connector...). It has not yet been verified
> that this connector is actually connected to any ground.


** Of course it is ground - you imbecile.

Grounding his body is what stops the hum since it prevents AC electric
field injecting into the pickup and wiring of the guitar.



> > Earthed strings will do that for him automatically.
>
> That would only affect the hum while he's touching the strings.


** Guitarists tend to do that.




............. Phil

 

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On 10 Sep 2004 15:02:13 -0700, mbyoungquist@hotmail.com (Matt from
Seattle) wrote:

>I have narrowed the hum down to the guitar, as you suspected. It hums
>not only when I go though the mixer, but also when just plugged in
>directly to my amp using a single 1/4" cable.

Is your system properly grounded? I believe some backward nations
(like the US ;-) allow ungrounded mains power connectors. Is your
system running from a grounded power outlet?

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"Possibly the world's least impressive web site": George Perfect

 

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"Laurence Payne" wrote...
> Is your system properly grounded? I believe some backward
> nations (like the US ;-) allow ungrounded mains power connectors.

Au contraire, grounded outlets are required everywhere for
new contstruction (AFAIK). And GFCI for anywhere where
there is moisture (bath, kitchen, outdoors, etc.) Furthermore,
ground-lift "adapters" (as mentioned by Mr. Shaw) are illegal
in all the jurisdictions I am familiar with.

 

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Richard Crowley <rcrowley7@xprt.net> wrote:
>"Laurence Payne" wrote...
>> Is your system properly grounded? I believe some backward
>> nations (like the US ;-) allow ungrounded mains power connectors.
>
>Au contraire, grounded outlets are required everywhere for
>new contstruction (AFAIK). And GFCI for anywhere where
>there is moisture (bath, kitchen, outdoors, etc.) Furthermore,
>ground-lift "adapters" (as mentioned by Mr. Shaw) are illegal
>in all the jurisdictions I am familiar with.

The code says that those adaptors can be used ONLY when connected to the
center screw of a box that is itself grounded, in order to provide a grounded
outlet in older buildings with ungrounded outlets.

Unfortunately, many of those older buildings use 2-conductor Romex or knob
and tube wiring, so the boxes are not grounded. Buildings wired with BX
cable, conduit, or 2-with-ground Romex are okay because there is a path
from the box to the panel ground.

On the other hand, 2-prong outlets ARE legal for new construction in Japan.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

 

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<< I believe some backward
> nations (like the US ;-) allow ungrounded mains power connectors. >>



While not disputing that the US is indeed a backward nation, grounded power has
been required in all aplications for many decades. Electrical code in the US is
a matter of local jurisdiction, although they all tend to update to
approximately the same level of safety considerations en masse. Mexico is
another matter, where I have yet to see a grounded outlet in any application.

Scott Fraser

 

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"Logan Shaw"
>
> Just to clear things up, here are some photos of a Guild F4CE:
>
> http/home.austin.rr.com/logan/guild-f4ce/
>

** Excellent pics - is that a volume knob on the side near the neck ??

Is there a pre-amp with a battery inside ??


> Unfortunately, it's just about impossible to see inside to tell what
the pickup is like.


** Piezo electric for sure - mounted somewhere under the bridge.


> All I can tell is that it there is a relatively
> thick (compared to the super-thin one that goes to the 1/4" output
> plug) cable headed towards the bridge.


** So there is ** SOMETHING ** in between ???

Did you never dream it might be an idea to describe it ?

Is it a box or just the volume pot ?

Based on the pics, that type of guitar does no have earthed strings. The PU
is supposed to be shielded well enough to do the job - but things can go
wrong. Earthing the strings will not be so simple - but may be the easiest
fix.



............. Phil

 

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On 12 Sep 2004 16:34:09 GMT, scotfraser@aol.com (ScotFraser) wrote:

>While not disputing that the US is indeed a backward nation, grounded power has
>been required in all aplications for many decades. Electrical code in the US is
>a matter of local jurisdiction, although they all tend to update to
>approximately the same level of safety considerations en masse.

Are 3-prong power plugs the norm?

CubaseFAQ www.laurencepayne.co.uk/CubaseFAQ.htm
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