[[email protected]]

We've got some nice pres here (Millenia, Symetrix, Great River, Manley)
but consistently run into problems of too much gain when tracking kit.
E.g. with the Millenia on its lowest settings a 451 on the bottom of
the snare clips our A/D convertor.

I'm considering two options, neither of which I know much about and
would appreciate any advice as to the merits of either:

1. Using an inline pad on the mic cable - Shure A15AS or Audio Technica
8202. Do these degrade the signal? Do they pass phantom power ok?

2. Skipping the preamps altogether and running the mics directly into
the A/D convertor. Would this work? My concerns are (i) would it be
loud enough? (ii) impedance issues? (iii) How to handle phantom power?
If we buy an inline phantom power box is this going to blow up the A/D
convertor? And does the quality of the phantom power unit affect the
sound quality? (e.g. Behringer do cheap little ones).

Any advice appreciated.

Thanks - Jon

[Scott Dorsey]

wrote:
We've got some nice pres here (Millenia, Symetrix, Great River, Manley)
but consistently run into problems of too much gain when tracking kit.
E.g. with the Millenia on its lowest settings a 451 on the bottom of
the snare clips our A/D convertor.

On the lowest setting, the HV-3 has about 18 dB of gain. I think the Great
River can be cranked down almost to unity.

I'm considering two options, neither of which I know much about and
would appreciate any advice as to the merits of either:

1. Using an inline pad on the mic cable - Shure A15AS or Audio Technica
8202. Do these degrade the signal? Do they pass phantom power ok?

They don't degrade the signal and they pass phantom power fine. Every
studio should have a drawer full of these. They are absolute and total
lifesavers for field recording work.

2. Skipping the preamps altogether and running the mics directly into
the A/D convertor. Would this work? My concerns are (i) would it be
loud enough? (ii) impedance issues? (iii) How to handle phantom power?
If we buy an inline phantom power box is this going to blow up the A/D
convertor? And does the quality of the phantom power unit affect the
sound quality? (e.g. Behringer do cheap little ones).

The phantom power unit has at least blocking capacitors and maybe a
transformer (unless it's the AKG unit, which allows phantom to appear
on the _output_ as well as the input). The quality of those capacitors
or transformer is still important.

The impedance is still an issue, but if you're going into an old-style
600 ohm input, most mikes will be happy. I used to run the RE-20 as a
kickdrum mike directly into the inputs of the Ampex with no problem.
There's no reason you can't do that also.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Sunflowermanuk]

Thanks Scott, sounds like a no-brainer solution then - I'm going
shopping for a clutch of inline attenuators to put between mic and pre.
Any preference make-wise or are they all much of a muchness?

Jon

Scott Dorsey wrote:
They don't degrade the signal and they pass phantom power fine. Every
studio should have a drawer full of these.

[Scott Dorsey]

Sunflowermanuk wrote:
Thanks Scott, sounds like a no-brainer solution then - I'm going
shopping for a clutch of inline attenuators to put between mic and pre.
Any preference make-wise or are they all much of a muchness?

I like the Shures, because you can run a truck over them without breaking
them and my Shure dealer will give me a discount on them. They're all
really just a couple resistors in a barrel, so there isn't a substantial
difference other than ruggedness.

The A-Ts are fine. I also have a bag of old GenRad ones around here somewhere
that are 30 dB fixed and also perfectly fine.

Normally for field recording I'll split the whole stage snake and pull it
into my multitrack rig, which has Millennia front ends. Occasionally folks
will be running a line level signal from something on stage down the snake.
I'll just stick a pad in there and keep going. The S/N isn't as good as
it would be if I bypassed the preamp, but it's so good anyway that it's not
an issue.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Mike Rivers]

Sunflowermanuk wrote:
Thanks Scott, sounds like a no-brainer solution then - I'm going
shopping for a clutch of inline attenuators to put between mic and pre.

For what it's worth, AKG used to make an attenuator for the C451 that
screwed between the capsule and body. Nowadays if you want one, you
have to pay about as much for it as a halfway decent preamp to some
greedy eBay seller. An outboard attenuator is fine, and there's no
appreciable difference between them. At least there shouldn't be - but
they used fixed resistors, and I doubt that any of them use better than
1% tolerance resistors. This could unbalance the input to the preamp
and reduce the common mode noise rejection, but if you're feeding a
huge signal voltage to the preamp, this isn't likely to be a concern.
But isn't it nice to have one more thing to worry about?

I believe Rich Chinn's web page http://www.uneeda-audio.com has a
section about building your own pads. If you care, you could build your
own out of 0.1% tolerance resistors. We got into this discussion not
too long ago and one of the Google wizards found at least one
attenuator's spec sheet that actually mentioned the tolerance or
matching of the resistors. It's most likely Shure since they're the
kind of company that would care to put that sort of data on their
sheets.

As long as the preamp isn't clipping, you might want to use it to get
whatever sound it imparts to the mic (putting a pad between the mic and
the preamp will change the loading of the preamp on the mic, which may
change the sound), and put the attenuator between the preamp output and
A/D converter input. Note that "change" does not necessarily mean
"degrade" unless you consider that any change, good or bad, is
degration.

But most A/D converters have input level controls unless yours is one
of those boxes that hooks to a computer and doesn't have any controls.
If you have knobs, use them before putting anything else in the signal
path.

[Sunflowermanuk]

As long as the preamp isn't clipping, you might want to use it to get
whatever sound it imparts to the mic (putting a pad between the mic and
the preamp will change the loading of the preamp on the mic, which may
change the sound), and put the attenuator between the preamp output and
A/D converter input.

I considered that putting a pad after the mic pre - would these little
mic attenuators also work in that conif (on line-level signals)? If so
I guess I could make some custom leads up and run them off the
patchbay.

FWIW I'm using an RME ADI8-Pro (into a Digi ADAT Bridge/Mix system).
It has switchable +4/-10/low gain inputs, but even on the latter it's
still too hot..

Thanks guys, invaluable stuff. Jon

[Sunflowermanuk]

As long as the preamp isn't clipping, you might want to use it to get
whatever sound it imparts to the mic (putting a pad between the mic and
the preamp will change the loading of the preamp on the mic, which may
change the sound), and put the attenuator between the preamp output and
A/D converter input.

I considered that putting a pad after the mic pre - would these little
mic attenuators also work in that config (on line-level signals)? If
so I guess I could make some custom leads up and run them off the
patchbay.

FWIW I'm using an RME ADI8-Pro (into a Digi ADAT Bridge/Mix system).
It has switchable +4/-10/low gain inputs, but even on the latter it's
still too hot..

Thanks guys, invaluable stuff. Jon

[anahata]

Mike Rivers wrote:
I doubt that any of them use better than
1% tolerance resistors. This could unbalance the input to the preamp
and reduce the common mode noise rejection, but if you're feeding a
huge signal voltage to the preamp, this isn't likely to be a concern.

Doesn't the usual configuration for a balanced pad involve no ground
connection? In that case any common mode signal will hardly be
attenuated at all by the pad, and hence there will be negligible
unbalancing of it either.

--
Anahata
-+- http://www.treewind.co.uk
Home: 01638 720444 Mob: 07976 263827

[anahata]

Sunflowermanuk wrote:

I considered that putting a pad after the mic pre

No use if the mic pre itself is clipping. Then you'll just feed an
attenuated clipped signal to the converter..

--
Anahata
-+- http://www.treewind.co.uk
Home: 01638 720444 Mob: 07976 263827

[Mike Rivers]

Sunflowermanuk wrote:

I considered that putting a pad after the mic pre - would these little
mic attenuators also work in that config (on line-level signals)?

No problem.

[Mike Rivers]

anahata wrote:

Doesn't the usual configuration for a balanced pad involve no ground
connection? In that case any common mode signal will hardly be
attenuated at all by the pad, and hence there will be negligible
unbalancing of it either.

It's not a matter of attenuation, it's a matter of the impedance that a
differential input sees when looking back at the source. There needs to
be the same impedance in each leg, and it still goes to ground (or
common) at the mic, unless you use a transformer. I'd have to think too
hard about it (and I won't try to argue with you) given tha the C451
has a transformer at its input. But my gut feeling is that if you put
unequal resistances in the two signal leads, in any case, the input
will still see unequal voltage drops from a common mode source and will
therefore have less common mode rejection.

Prove it to yourself that you don't have to worry about a balanced
attenuator if you wish. Doing it right is just good practice.

[Scott Dorsey]

Sunflowermanuk wrote:
As long as the preamp isn't clipping, you might want to use it to get
whatever sound it imparts to the mic (putting a pad between the mic and
the preamp will change the loading of the preamp on the mic, which may
change the sound), and put the attenuator between the preamp output and
A/D converter input.

I considered that putting a pad after the mic pre - would these little
mic attenuators also work in that conif (on line-level signals)? If so
I guess I could make some custom leads up and run them off the
patchbay.

Yes. The attenuators will work just fine on line signals unless you
absolutely need to be running 600 ohm constant power somewhere.

You used to be able to buy attenuating patch cords too (which WERE
designed for 600 ohm constant power) but I haven't seen them for a
while. Be easy to make your own, though.

Even so, if you don't know how much headroom you have left, you might
as well just attenuate before the preamp.

FWIW I'm using an RME ADI8-Pro (into a Digi ADAT Bridge/Mix system).
It has switchable +4/-10/low gain inputs, but even on the latter it's
still too hot..

Yes, to be honest the older ADI-8 sounds better with the gain set to
the high or medium setting. I don't know why.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Arny Krueger]

"anahata" wrote in message
...
Mike Rivers wrote:
I doubt that any of them use better than
1% tolerance resistors. This could unbalance the input to the preamp
and reduce the common mode noise rejection, but if you're feeding a
huge signal voltage to the preamp, this isn't likely to be a concern.

Doesn't the usual configuration for a balanced pad involve no ground
connection?

Yes.

In that case any common mode signal will hardly be attenuated at all by
the pad, and hence there will be negligible unbalancing of it either.

That's why most balanced pads have no ground.

[Arny Krueger]

"anahata" wrote in message
...
Sunflowermanuk wrote:

I considered that putting a pad after the mic pre

No use if the mic pre itself is clipping. Then you'll just feed an
attenuated clipped signal to the converter..

Agreed, but the world is full of mic preamps that will put out +22 or more,
and converters that clip at +16 or less.

[Paul Stamler]

"Mike Rivers" wrote in message
ups.com...

Sunflowermanuk wrote:

I considered that putting a pad after the mic pre - would these little
mic attenuators also work in that config (on line-level signals)?

No problem.

Well, sometimes no problem. Some of those mic attenuators have input
impedances of 150 ohms, which is kind of low for loading a preamp. Come to
think of it, it's kind of low for a C451 as well. So check the attenuators'
input Z before you buy. If necessary, make up your own -- let the input Z be
1500 ohms and you should be happy.

Peace,
Paul

[John L Rice]

wrote in message
oups.com...
We've got some nice pres here (Millenia, Symetrix, Great River, Manley)
but consistently run into problems of too much gain when tracking kit.
E.g. with the Millenia on its lowest settings a 451 on the bottom of
the snare clips our A/D convertor.

I'm considering two options, neither of which I know much about and
would appreciate any advice as to the merits of either:

1. Using an inline pad on the mic cable - Shure A15AS or Audio Technica
8202. Do these degrade the signal? Do they pass phantom power ok?

In addition to the other fine advice you already received you might be
interested in a couple devices A-Designs makes :

The ATTY (rhymes with "Patty") is a low-cost, no-noise, compact device
designed for audio level control. It features dual audio INs and OUTs, a
level control knob, and a mute button.
http://www.adesignsaudio.com/atty.htm


The ATTY2'D (pronounced "Attitude"), is the big brother of the successful
ATTY passive audio line level controller. It offers fully independent
control over two stereo pairs and two mono signals
http://www.adesignsaudio.com/atty2d.htm

Best of luck!

--
John L Rice
www.DeliriumFix.com

[Arny Krueger]

wrote in message
oups.com...
We've got some nice pres here (Millenia, Symetrix, Great River, Manley)
but consistently run into problems of too much gain when tracking kit.
E.g. with the Millenia on its lowest settings a 451 on the bottom of
the snare clips our A/D convertor.

I'm considering two options, neither of which I know much about and
would appreciate any advice as to the merits of either:

1. Using an inline pad on the mic cable - Shure A15AS or Audio Technica
8202. Do these degrade the signal?

No, and their impedance levels are such that they work well with many
line-level sources as well, around 1K.

Do they pass phantom power ok?

Yes. Used mine that way many times.

[Kurt Albershardt]

Sunflowermanuk wrote:

FWIW I'm using an RME ADI8-Pro (into a Digi ADAT Bridge/Mix system).
It has switchable +4/-10/low gain inputs, but even on the latter it's
still too hot..

You may be able to run the mic directly into the ADI-8 set on -10 dB.

[Daniel Fuchs]

Kurt Albershardt wrote:

You may be able to run the mic directly into the ADI-8 set on -10 dB.

Without phantom power? ;-)

Daniel

[Tom Garneau]

John L Rice wrote:

wrote in message
oups.com...
We've got some nice pres here (Millenia, Symetrix, Great River, Manley)
but consistently run into problems of too much gain when tracking kit.
E.g. with the Millenia on its lowest settings a 451 on the bottom of
the snare clips our A/D convertor.

I'm considering two options, neither of which I know much about and
would appreciate any advice as to the merits of either:

1. Using an inline pad on the mic cable - Shure A15AS or Audio Technica
8202. Do these degrade the signal? Do they pass phantom power ok?

In addition to the other fine advice you already received you might be
interested in a couple devices A-Designs makes :

The ATTY (rhymes with "Patty") is a low-cost, no-noise, compact device
designed for audio level control. It features dual audio INs and OUTs, a
level control knob, and a mute button.
http://www.adesignsaudio.com/atty.htm


The ATTY2'D (pronounced "Attitude"), is the big brother of the successful
ATTY passive audio line level controller. It offers fully independent
control over two stereo pairs and two mono signals
http://www.adesignsaudio.com/atty2d.htm

Best of luck!

What's Retail Price?

thanks,

tom