[Tobiah]

I have a friend with an electric bass, and I have a Takamini
classical with electronics. When he comes over we often both
plug right into the 1402-VLZPro. It sounds fine to me, but I
wonder about impedance. Some of the higher end Mackies have
a switch on the first two channels that is meant to accommodate
electric guitars.

I checked out direct boxes, but they look like they are meant to
feed the mic in on the mixer rather than the line in. You may
say that if it sounds fine, then what more do I want. I want to
know if there is a better way.

Thanks,

Tobiah

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[Mike Rivers[_2_]]

On 6/28/2014 8:11 PM, Tobiah wrote:

I have a friend with an electric bass, and I have a Takamini
classical with electronics. When he comes over we often both
plug right into the 1402-VLZPro. It sounds fine to me, but I
wonder about impedance.

The line input impedance and gain on the VLZ-Pro is marginal for passive
instrument pickups but should be OK for instruments with active
electronics. But if it sounds OK to you and you don't have any good
reason to see if it could sound better, go with what works.

I checked out direct boxes, but they look like they are meant to
feed the mic in on the mixer rather than the line in.

Yes, that's how they work. A direct box provides a high (typically
around 1 megohm) impedance input for the instrument and converts that to
a balanced fairly hot mic level output. You get the advantage of the
balanced connection if you need to run a long cable between the direct
box and the mixer like when you're playing on stage and the mixer is off
stage, perhaps at the back of the room. You could have some gain in the
direct box (and some indeed have line level outputs) but mic preamps
have plenty of gain, they're quiet, and they're balanced, so the classic
direct box design is a good one.


--
For a good time, visit http://mikeriversaudio.wordpress.com

[Tobiah]

On 6/28/2014 5:51 PM, Mike Rivers wrote:
On 6/28/2014 8:11 PM, Tobiah wrote:

I have a friend with an electric bass, and I have a Takamini
classical with electronics. When he comes over we often both
plug right into the 1402-VLZPro. It sounds fine to me, but I
wonder about impedance.

The line input impedance and gain on the VLZ-Pro is marginal for passive
instrument pickups but should be OK for instruments with active
electronics. But if it sounds OK to you and you don't have any good
reason to see if it could sound better, go with what works.

I'm just starting to read up on impedance - it's always been some
mystery to me. When you say that the VLZPro input impedance is
'marginal for passive instrument pickups', can you give me some sense
of the values involved, and what sort of fidelity degradation I should
be looking for?

I checked out direct boxes, but they look like they are meant to
feed the mic in on the mixer rather than the line in.

Yes, that's how they work. A direct box provides a high (typically
around 1 megohm) impedance input for the instrument and converts that to
a balanced fairly hot mic level output. You get the advantage of the
balanced connection if you need to run a long cable between the direct
box and the mixer like when you're playing on stage and the mixer is off
stage, perhaps at the back of the room. You could have some gain in the
direct box (and some indeed have line level outputs) but mic preamps
have plenty of gain, they're quiet, and they're balanced, so the classic
direct box design is a good one.



Thanks for the information. You've been helpful.

Tobiah

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[Scott Dorsey]

In article , Tobiah wrote:
I have a friend with an electric bass, and I have a Takamini
classical with electronics. When he comes over we often both
plug right into the 1402-VLZPro. It sounds fine to me, but I
wonder about impedance. Some of the higher end Mackies have
a switch on the first two channels that is meant to accommodate
electric guitars.

If it sounds fine, don't worry about it.

The Takamine probably has a pretty low output Z and is probably happy
enough. The bass probably has a pretty high output Z and the top end
is probably severely rolled off, but if you like the sound that's fine.

I checked out direct boxes, but they look like they are meant to
feed the mic in on the mixer rather than the line in. You may
say that if it sounds fine, then what more do I want. I want to
know if there is a better way.

The direct box will let you run a long balanced cable without any
worries about noise pickup. This is very important if you're on
stage and the console is down the end of several hundred feet of
cable.

If you were to put that bass on a good active DI, I guarantee it
would sound a lot brighter. You might hate that, though.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Nil[_2_]]

On 28 Jun 2014, Tobiah wrote in rec.audio.pro:

I have a friend with an electric bass, and I have a Takamini
classical with electronics. When he comes over we often both
plug right into the 1402-VLZPro. It sounds fine to me, but I
wonder about impedance. Some of the higher end Mackies have
a switch on the first two channels that is meant to accommodate
electric guitars.

I have that mixer, and I've tried plugging passive guitars and basses
into it both with and without a direct box. The direct box method
sounds significantly better.

[Nate Najar]

If you want cheap, for the bass, use the avenson small DI. For more money and ore versatility down the line if that becomes important, the fire eye Redeye is incredible. I use it so much for so many things I don't know how I lived without it.

The takamine with its active preamp is perfectly happy with the line in on the mackie as is.

[Jay Ts[_4_]]

On Sat, 28 Jun 2014, Tobiah wrote:
I have a friend with an electric bass, and I have a Takamini classical
with electronics. When he comes over we often both plug right into the
1402-VLZPro. It sounds fine to me, but I wonder about impedance.

The active circuitry in your guitar "should" work fine, but if the bass
has passive electronics, there might be a slight loss of high frequencies.

Electric basses usually have a hotter output than electric guitars, and
since it's called a "bass", not a "treble", maybe you won't lose so much
high frequencies, and maybe they are not so important anyway. ;-) Maybe
it is fine as-is.

Some
of the higher end Mackies have a switch on the first two channels that
is meant to accommodate electric guitars.

It probably just switches in a higher value of resistor in the input
circuit.

Passive electric guitars/basses have high impedance outputs (imagine a
trickle of water coming out of a faucet), so you want an even higher
impedance (imagine a very tiny drain hole in the sink) at the input of
the next thing in the chain (effects pedal or mixer input) to preserve
the signal quality.

I checked out direct boxes, but they look like they are meant to feed
the mic in on the mixer rather than the line in.

Yes, that's it. A direct box basically makes a guitar look like a
microphone to the mixer (mic pre). If you have a 1/4" line input at the
mixer, you probably don't need a direct box. One advantage with using a
direct box is that you can use a short guitar cable with less
capacitance, and get a brighter sound if the instrument is passive.

IMO, the main reason for a direct box is if the guitar needs a very long
cable (like 100 feet) to reach the mixer. In that case, you want to use a
low-impedance balanced cable (mic cable) instead.

Also, I think that direct boxes are often recommended in this situation
because recording engineers are familiar with using microphones, and it's
a "knee jerk reaction" that is sure to work. There is nothing at all
wrong with using one, but there are other ways ...

I want to know if there is a better way.

I suggest you look at preamp effects boxes. There are many designed for
electric guitar, and a few for electric bass. It will allow you to raise
the level of the signal to line level if you want, and also will have a
low impedance output to drive whatever impedance the mixer line input
has. (Which might be only 10k-25k. Check your spec sheet. It should be
listed.)

I've never used one, but you can look at the MXR M81 Bass Preamp. (Just
to name one example.)

Like a direct box, you can use a short cable to the preamp, and then a
longer cable to the mixer input, without the capacitance of the long
cable altering the instrument's tone.

[Jay Ts[_4_]]

On Sat, 28 Jun 2014, Tobiah wrote:
I'm just starting to read up on impedance - it's always been some
mystery to me. When you say that the VLZPro input impedance is
'marginal for passive instrument pickups', can you give me some sense of
the values involved, and

what sort of fidelity degradation I should be
looking for?

You can think of impedance like resistance. Impedance is more generalized
to include AC signals rather than just DC.

To make it intuitive, you can imagine electrical signals as being like
air (or any liquid or gas fluid) flowing through a tube. A larger
diameter is less resistance/impedance, and a smaller one is higher.

Imagine you are blowing through a small-diameter straw. that is like high
impedance. But if you are blowing through that into a tube that is a foot
in diameter, you won't move much air in the big tube. That is like
plugging a high impedance output into a low impedance input.

Turn it around, and if you have a large tube blowing air into a much
smaller one, then you will easily get the air moving in the small tube.
This is like having a low impedance output going into a high impedance
input.

what sort of fidelity degradation I should be looking for?

Usually loss of high frequencies, but in extreme cases, overall signal
(amplitude) loss.

[Mike Rivers[_2_]]

On 6/28/2014 9:08 PM, Tobiah wrote:

I'm just starting to read up on impedance - it's always been some
mystery to me. When you say that the VLZPro input impedance is
'marginal for passive instrument pickups', can you give me some sense
of the values involved, and what sort of fidelity degradation I should
be looking for?

The line input of the mic/line channels of a VLZ-Pro presents a load of
about 7k Ohms to an unbalanced source (like and instrument pickup). It's
double that when fed from a balanced source. The line-only inputs (the
stereo channels) are about 10k Ohms unbalanced.

What you can expect is the pickup level in general attenuated by about 6
dB so you might need more gain than with a higher load impedance, and
hence get a bit more noise. You might also have some high frequency loss.

Thanks for the information. You've been helpful.

Visit my web site and look up the article about impedance. That might
answer more questions that you haven't asked yet.



--
For a good time, visit http://mikeriversaudio.wordpress.com

[Sean Conolly]

"Nate Najar" wrote in message
...
If you want cheap, for the bass, use the avenson small DI. For more money
and ore versatility down the line if that becomes important, the fire eye
Redeye is incredible. I use it so much for so many things I don't know
how I lived without it.

The takamine with its active preamp is perfectly happy with the line in on
the mackie as is.

I made my own little DI so I could run the guitar directly into my Moto -
just an unbalanced booster to add 12 db or so and push more current.
Actually it goes though a patch-bay to split into the board for monitoring &
effects and dry into the Motu for recording. Now it's the only thing I want
to play through.

Sean

[Jay Ts[_4_]]

On Sun, 29 Jun 2014, Sean Conolly wrote:
The takamine with its active preamp is perfectly happy with the line in
on the mackie as is.

I made my own little DI so I could run the guitar directly into my Moto
- just an unbalanced booster to add 12 db or so and push more current.

Yes, that's it. All you need is a simple voltage follower circuit with
high input impedance and low output impedance. Just make sure you have
good frequency response, etc.

I haven't tested many guitars, but for mine, 12 dB of gain works just
right.

[Jay Ts[_4_]]

On Sun, 29 Jun 2014, Jay Ts wrote:

I suggest you look at preamp effects boxes. [..]

and if you have *any* guitar or bass effects pedal on hand, you can try
it just to get a quick idea, before plunking down money on a bass preamp.

Most (if not all) effects pedals have a much lower output impedance than
a guitar with passive electronics, and should get you in the range you
need (or close enough) to properly drive your mixer's line input.

[Tobiah]

The line input impedance and gain on the VLZ-Pro is marginal for passive
instrument pickups but should be OK for instruments with active
electronics.

His bass does take a battery.

Tobiah


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[Jay Ts[_4_]]

On Sun, 29 Jun 2014, Tobiah wrote:
The line input impedance and gain on the VLZ-Pro is marginal for
passive instrument pickups but should be OK for instruments with active
electronics.

His bass does take a battery.

Then it should be fine. (Unless the circuit was badly designed.)