Hi,
a while ago I started thinking about a building a balanced output on my bass guitar.
Almost all professional microphones have balanced outputs. There are several advantages over a single-ended output. For one you pick up less noise on a balanced connection. But why do (bass) guitars still come with a single-ended output? For microphones single-ended connections are considered not very professional. Why do we guitarists still use em?
Most modern bass guitars have an onboard preamp. I don't think this is very common on guitars though. A preamp raises the output level and lowers the output impedance, which are good things. But now you have a battery which can (and will) run flat when you're on stage in the middle of a show, and have no spare at hand. The microphone people fixed this by using phantom power. This way the microphone is powered from the mixing desk. No more empty batteries! So why not use that on your (bass) guitar as well?
Have you guys ever considered this? What do you think of it?
Cheers,
Maarten
a while ago I started thinking about a building a balanced output on my bass guitar.
Almost all professional microphones have balanced outputs. There are several advantages over a single-ended output. For one you pick up less noise on a balanced connection. But why do (bass) guitars still come with a single-ended output? For microphones single-ended connections are considered not very professional. Why do we guitarists still use em?
Most modern bass guitars have an onboard preamp. I don't think this is very common on guitars though. A preamp raises the output level and lowers the output impedance, which are good things. But now you have a battery which can (and will) run flat when you're on stage in the middle of a show, and have no spare at hand. The microphone people fixed this by using phantom power. This way the microphone is powered from the mixing desk. No more empty batteries! So why not use that on your (bass) guitar as well?
Have you guys ever considered this? What do you think of it?
Cheers,
Maarten
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It's all been done before - but there's little need or reason, most of your points apply to microphones and not to guitars or bass.
An active guitar/bass overcomes all the limitations that a microphone suffers from, but even a passive guitar/bass is so much better you don't need balancing.
An active guitar/bass overcomes all the limitations that a microphone suffers from, but even a passive guitar/bass is so much better you don't need balancing.
You are looking at just one aspect of signal without looking at the whole context.
The advantage of a balanced line is that it picks up less noise on a long run. But your bass guitar generally does not have a long signal run. I never use longer than a 20 foot cord, and if you use floor toys it may be even shorter. Very seldom would one have no stage amp and play directly through the PA mixer, most guys at least want control over their stage volume and their tone. And if you have a stage amp, then a balanced line out from that is much more convenient. And for amps that lack that, a "direct box" is a tool most competent sound men will have on hand.
Professional microphones usually have balanced conections, yes. Those intended for live sound are probably going to be connected through a hundred feet or more of cable before they get to a preamp of any sort. And in recording, the distance from the studio to the mixer itself can still be quite lengthy, and the noise issues are way more important in the studio.
Noise is important when compared to signal. A microphone, at least a good one, puts out a very low level signal, contrasting to your bass which puts out a pretty strong signal. The signal to noise ratio for your bass will be much greater than for a microphone.
Some mics need phantom power, you will find those are condenser mics, which need a power supply by their nature. Many bass guitars do have preamps, I don;t know that I would go so far as to say most, though. You could make an onboard preamp circuit that runs on phantom, but then your bass would require always running into a PA mixer or having an amplifier that provides phantom, or adding a phantom supply accessory. All of that is unnecessarily complicating the passive arrangement that has worked extremely well the last six or seven decades.
The advantage of a balanced line is that it picks up less noise on a long run. But your bass guitar generally does not have a long signal run. I never use longer than a 20 foot cord, and if you use floor toys it may be even shorter. Very seldom would one have no stage amp and play directly through the PA mixer, most guys at least want control over their stage volume and their tone. And if you have a stage amp, then a balanced line out from that is much more convenient. And for amps that lack that, a "direct box" is a tool most competent sound men will have on hand.
Professional microphones usually have balanced conections, yes. Those intended for live sound are probably going to be connected through a hundred feet or more of cable before they get to a preamp of any sort. And in recording, the distance from the studio to the mixer itself can still be quite lengthy, and the noise issues are way more important in the studio.
Noise is important when compared to signal. A microphone, at least a good one, puts out a very low level signal, contrasting to your bass which puts out a pretty strong signal. The signal to noise ratio for your bass will be much greater than for a microphone.
Some mics need phantom power, you will find those are condenser mics, which need a power supply by their nature. Many bass guitars do have preamps, I don;t know that I would go so far as to say most, though. You could make an onboard preamp circuit that runs on phantom, but then your bass would require always running into a PA mixer or having an amplifier that provides phantom, or adding a phantom supply accessory. All of that is unnecessarily complicating the passive arrangement that has worked extremely well the last six or seven decades.
Microphones and guitars (or actually microphone capsules and pick-ups) are quite similar. Both are a weak signal source with reasonably high output impedance. I was surprised at the difference in approach for getting the signal to the amplifier.
I admit that guitar leads are often shorter than microphone leads and signal levels are higher for guiter than for microphone, so noise will be less of an issue for guitar.
I was hoping to learn from the problems fixed in the microphone department and apply the knowledge to my bass guitar.
I admit that guitar leads are often shorter than microphone leads and signal levels are higher for guiter than for microphone, so noise will be less of an issue for guitar.
I was hoping to learn from the problems fixed in the microphone department and apply the knowledge to my bass guitar.
An amazing number of mics (condensor type) are actually single-ended signalwise, they only use impedance balancing (requiered anyway by the 48V phantom feed) which is the key to "noiseless" balanced connects.
You can have that with a bass, too : Insert a buffer preamp to have a stable and defined output impedance of, say, 100Ohms, then insert the same resistance in the "cold" lead of the XLR socket. As had been said before, the net benfit is effectively zero (been there, done that). If you want a quiet bass, use humbuckers with good coil matching, shield everything (including pups) thoroughly and probably add a buffer for low treble loss and higher cable noise immunity, plus a quality cable.
You can have that with a bass, too : Insert a buffer preamp to have a stable and defined output impedance of, say, 100Ohms, then insert the same resistance in the "cold" lead of the XLR socket. As had been said before, the net benfit is effectively zero (been there, done that). If you want a quiet bass, use humbuckers with good coil matching, shield everything (including pups) thoroughly and probably add a buffer for low treble loss and higher cable noise immunity, plus a quality cable.
Hi,
Passive basses and guitars cannot work with balanced
microphone inputs, the input impedance is far too low.
Source impedance of a microphone is much lower than
guitar pickups, and passive guitar pickups rely on
resonating with cable capacitance and a >1M input.
My active bass also has a passive mode. A guitar
needing phantom power is just a very silly idea.
You can add XLR to a bass, but you'd still keep
the standard output if you've got any sense.
Its an onboard DI, which isn't needed much.
rgds, sreten.
Passive basses and guitars cannot work with balanced
microphone inputs, the input impedance is far too low.
Source impedance of a microphone is much lower than
guitar pickups, and passive guitar pickups rely on
resonating with cable capacitance and a >1M input.
My active bass also has a passive mode. A guitar
needing phantom power is just a very silly idea.
You can add XLR to a bass, but you'd still keep
the standard output if you've got any sense.
Its an onboard DI, which isn't needed much.
rgds, sreten.
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That's because your original premise is incorrect, microphones and guitars are nothing alike - guitars (at least passive ones) are high impedance and high signal level. Microphones are low impedance and low signal levels.
If you used microphones back in the 'old days' they were often 'high' impedance (50K nominally - guitars are a good bit higher), and could use the same unbalanced inputs as a guitar - as long as the input had enough sensitivity to accept the far lower signal.
So your reasoning is all wrong, the only 'worthwhile' reason to balance a guitar would be for an active one, just to get the phantom power.
But as you generally wouldn't be plugging a guitar directly in to a mixer, it's not really worth it - but goggle if you like, it's been done many times.
The drop to low impedance microphones was to allow MUCH longer leads without high frequency loss, and the resultant huge drop in signal meant balancing became much more essential.
Many good quality mics, like the famous Shure SM57 or SM58, have a high impedance capsule, then there is also a small transformer in the body of the mic to convert that to the low-Z balanced output.
Your bass pickup has a FAR higher output level than a microphone does.
Your bass pickup has a FAR higher output level than a microphone does.
I always thought it was the other way round, the capsule in a SM57 was very low impedance so the voice coil wire would be thick enough to manage at the factory, and the transformer stepped it UP. 🙂
But yes, the fundamental difference is that an electric guitar or bass gives a much bigger signal than a microphone, so there isn't really any need for balancing. Guitarists have also got used to the high frequency loss that comes from the high impedance connection.
I believe the Les Paul Recording had a low impedance balanced output meant for connection to a mic pre.
But yes, the fundamental difference is that an electric guitar or bass gives a much bigger signal than a microphone, so there isn't really any need for balancing. Guitarists have also got used to the high frequency loss that comes from the high impedance connection.
I believe the Les Paul Recording had a low impedance balanced output meant for connection to a mic pre.
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Yes, that Les Paul was not made in huge numbers and that is not a common feature. it really didn;t do much that anyone needed done.
I would say the main high end loss in a guitar rig is the guitar cord capacitance. But between the amp and speaker there is little in a guitar sound over about 5kHz, so we can manage a little high end loss.
Other than precision and quality, the capsule in the SM57 is not substantially different from the ones in one of their high Z mics of the era. If I need to function check an SM57 capsule, I just clip it to an amp. SHure Bros are quite used to dealing with tiny wire.
I would say the main high end loss in a guitar rig is the guitar cord capacitance. But between the amp and speaker there is little in a guitar sound over about 5kHz, so we can manage a little high end loss.
Other than precision and quality, the capsule in the SM57 is not substantially different from the ones in one of their high Z mics of the era. If I need to function check an SM57 capsule, I just clip it to an amp. SHure Bros are quite used to dealing with tiny wire.
I would entirely agree - the Shure microphones I've had to pieces had a transformer in for the high impedance versions and NO transformer in the low impedance versions.
Incidentally, anyone know what goes wrong with Shure mike inserts?, they seem to die after a few years? - they don't go O/C or anything, but go low output and low quality.
Thanks guys for sharing this information. I'll direct my energy towards something more useful than building an xlr into my bass. Building a bass preamp for instance 🙂
But why only Shure?, or is it just that there's a LOT more Shure mikes about than others?.
This. And SM57/58 see little to no care at all by many techs, getting knocked around and their baskets never cleaned...
I have an SM58 in my hand. I screwed off the element and am looking at the matching transformer inside.
Here is the SM57 user guide, refer to page 12 of it for the internal wiring diagram.
http://cdn.shure.com/user_guide/upload/1554/us_pro_sm57_ug.pdf
http://homerecording.com/bbs/specia...brew/replacing-transformer-shure-sm57-273513/
Here is the SM57 user guide, refer to page 12 of it for the internal wiring diagram.
http://cdn.shure.com/user_guide/upload/1554/us_pro_sm57_ug.pdf
http://homerecording.com/bbs/specia...brew/replacing-transformer-shure-sm57-273513/
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Hi,
I don't know. Things like how well magnets keep their magnetism
(coercivity) when repeatedly hit by a hammer are difficult to find.
Some may be better than the Shures, a lot may be worse.
I suspect many low grade microphones are much worse.
rgds, sreten.
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