Connecting a line level device into a Mic input without a pad...?

[kwilliams]

How??? what device can I use to match the two?? obviously the input is way too hot.
Thanks in advance..

[NathanEldred]

I would think a pad would be the most pure way....what's wrong with a pad?

[kwilliams]

Sorry I should've been more explicit....the device I'm trying to go into doesn't have a pad. It has a mic input with no pad....I'm trying to use it as a hardware insert in protools and send audio out of my PT interface into the pre and use its e.q's. only. Since the PT outputs are line outs, the outputs are way too hot to go into the mic inputs on this device with the gain all the way down...

[NathanEldred]

Originally Posted by kwilliams

Sorry I should've been more explicit....the device I'm trying to go into doesn't have a pad. It has a mic input with no pad....I'm trying to use it as a hardware insert in protools and send audio out of my PT interface into the pre and use its e.q's. only. Since the PT outputs are line outs, the outputs are way too hot to go into the mic inputs on this device with the gain all the way down...

Buy an inline pad like the Shure model, it's cheap and invaluable in any studio. You can put it between any two devices where it's needed, such as your converter's line level output, and the input of the microphone preamp. My most common use for them is between a microphone output and the input of the mic preamp.

[kwilliams]

Originally Posted by NathanEldred

Buy an inline pad like the Shure model, it's cheap and invaluable in any studio. You can put it between any two devices where it's needed, such as your converter's line level output, and the input of the microphone preamp. My most common use for them is between a microphone output and the input of the mic preamp.

An inline pad!! there you go...all I had to do is ask!!!thanks Nathan
From your experience are there any chances of 'sound coloration' from this device or are they of no effect to the audio passing through them?

[NathanEldred]

Originally Posted by kwilliams

An inline pad!! there you go...all I had to do is ask!!!thanks Nathan
From your experience are there any chances of 'sound coloration' from this device or are they of no effect to the audio passing through them?

No change that should really be worried about IMO, maybe only concern for the entire stereo mix, but for individual tracks within the context of a mix probably not...

[kwilliams]

cool..thanks

[Screws]

Or, for a bit more elegant solution:

http://www.adesignsaudio.com/atty.htm

[usamike]

Why not print it to another track and just turn the fader down til you get the input gain you want? Wouldn't that work? Just a suggestion- I am acutally planning on trying the same thing, but sending a line level signal through a guitar pedal. I'll let you know how it works out.

Later,

Mike

[brianroth]

Units like the Shure inline pads may not be the proper answer since they are designed to work in an "250 Ohms impedance world", while your line outputs are designed to work into a much higher impedance load.

It's not all that complicated to concoct a pad with a few resistors that presents a 10K (for example) load to the line level output while also presenting a 250 Ohm source impedance into the preamp. Here's a tutorial my friend Rick Chinn has posted:

http://www.uneeda-audio.com/pads/

The table at the very bottom of the page has resistor values to drop a line level signal to mic level.

Bri

[the kid]

Would placing a Folcrom between the line level device and mic pre work?

[TheSweetener]

Originally Posted by usamike

Why not print it to another track and just turn the fader down til you get the input gain you want?

Because the quality of your D/A conversion will suffer. You have to try if that really bothers you. I think it depends on the amount of level reduction.

[ulysses]

Originally Posted by the kid

Would placing a Folcrom between the line level device and mic pre work?

Sure it would, but it costs at least $750 more than an inline pad. In fact, if you use a single input and a single output of the Folcrom, it IS nothing more than an inline pad.

You can easily build your own pad into a patch cord or XLR cable. You need three resistors and the ability to make your own patch cable (that's a separate thread). Make the cable as you normally would, but at one end (the "source" end) you solder a 7500-ohm resistor in line between the connector and the wire. Do this on both the "hot" pin and the "cold" pin. Then, at the "load" end of the cable (the other connector) you solder the wires directly to the connector just like a regular patch cord but you ALSO connect a 150-ohm "shunt" resistor BETWEEN the hot and cold pins. Connect the cable shield to the connector ground at both ends (or just one end) as you normally would. This will give you a pad that's approximately 40dB (about right for turning a line-level signal into a mike-level signal). It will also load your line-level output with about 15k ohms, which is just fine. And it will present a source impedance to the mike preamp that's very close to 150 ohms, which is what most preamp are expecting. You could screw around with the resistor values a bit if you wanted, but you're limited somewhat by the fact that you need a relatively high input imedance and a specific output impedance. If you want less than 40dB of gain, you could go down to about 4700 ohms for the two series resistors and up to about 250 ohms for the shunt resisor without too much effect on the impedance. Those values would give you approximately 32dB attenuation.

The question of whether a resistive pad will affect the tonality of the source or the preamp. The answer is that any potential change in tone will depend on the specific gear in question and in any case will be proportional to the deviation from the "ideal" source impedances. Keep the input impedance high and the ooutput impedance at 150 ohms and you will have a sonically neutral pad.

Of course the biggest tonal change will come from the fact that the mike preamp will no longer be overloaded and clipping from the line-level input.

[James Lehmann]

Originally Posted by usamike

...sending a line level signal through a guitar pedal...

I use a LittleLabs Redeye for this task. What is needed here is a High Impedance UNBALANCED output which the Redeye delivers, ie a Re-Amp. Of course for the original poster's aplication we need a High Impedance BALANCED signal (which the multi-functional little wonder Redeye does too) but wouldn't a simple DI box do the job OK as well in this case?

[Jim Williams]

Originally Posted by ulysses

Sure it would, but it costs at least $750 more than an inline pad. In fact, if you use a single input and a single output of the Folcrom, it IS nothing more than an inline pad.

You can easily build your own pad into a patch cord or XLR cable. You need three resistors and the ability to make your own patch cable (that's a separate thread). Make the cable as you normally would, but at one end (the "source" end) you solder a 7500-ohm resistor in line between the connector and the wire. Do this on both the "hot" pin and the "cold" pin. Then, at the "load" end of the cable (the other connector) you solder the wires directly to the connector just like a regular patch cord but you ALSO connect a 150-ohm "shunt" resistor BETWEEN the hot and cold pins. Connect the cable shield to the connector ground at both ends (or just one end) as you normally would. This will give you a pad that's approximately 40dB (about right for turning a line-level signal into a mike-level signal). It will also load your line-level output with about 15k ohms, which is just fine. And it will present a source impedance to the mike preamp that's very close to 150 ohms, which is what most preamp are expecting. You could screw around with the resistor values a bit if you wanted, but you're limited somewhat by the fact that you need a relatively high input imedance and a specific output impedance. If you want less than 40dB of gain, you could go down to about 4700 ohms for the two series resistors and up to about 250 ohms for the shunt resisor without too much effect on the impedance. Those values would give you approximately 32dB attenuation.

The question of whether a resistive pad will affect the tonality of the source or the preamp. The answer is that any potential change in tone will depend on the specific gear in question and in any case will be proportional to the deviation from the "ideal" source impedances. Keep the input impedance high and the ooutput impedance at 150 ohms and you will have a sonically neutral pad.

Of course the biggest tonal change will come from the fact that the mike preamp will no longer be overloaded and clipping from the line-level input.

This is how you do it. Do use quality resistors, like Dale RN55's from Mouser. Match the two series resistors with a meter for better than 1/2 % to maintain CMRR. This can be installed into an empty Switchcraft barrel extender. Keep in mind this will affect phantom power so don't try to use it with this pad inserted.
Many low cost consoles do this to pad the inputs as they only have a mic pre in, not a line circuit. Soundcraft 600's come to mind.

Jim Williams
Audio Upgrades

[quincyg]

ullyses and Jim,
people like you are what make this forum great! i have no need for this application, but it is really cool when people break down the howto's for specific applications. gearslutz is the best thing i have found on the internet in years!

thanks,
quincy

[max cooper]

Originally Posted by quincyg

ullyses and Jim,
people like you are what make this forum great! i have no need for this application, but it is really cool when people break down the howto's for specific applications. gearslutz is the best thing i have found on the internet in years!

You mean besides the Carolyn Murphy Cell Phone pictures, right?


I agree. I've been needing to make a few of these to have around.

[dj_who]

i don't mean to hijack the thread.......but.......as far as using a mic, would anyone prefer the shure pad to say the built in pad in the great river for example? or would you say it doesn't matter which ?

[DeepSpace]

Originally Posted by dj_who

i don't mean to hijack the thread.......but.......as far as using a mic, would anyone prefer the shure pad to say the built in pad in the great river for example? or would you say it doesn't matter which ?

Unless you have reason to be suspicious of a built in pad in a pre (and with Great River, equipment failures aside you should be fine!) then I'd say it is best to go with the existing (built-in) pad. Reason being that you can expect that the built-in pad is *exactly* optimized for the impedance of the pre input, whereas the Shure pad (or another inline pad will be generic rather than optimal for the specific pre.

[dj_who]

cool thanks

[Jim Williams]

The outboard pad would mess with the phantom supply. In mic pre's, the phantom is applied on the mic side of the pad resistors.

Jim Williams
Audio Upgrades

[joeq]

not cheap but it's red

[TonyBelmont]

USE A FREAKIN' DI!

[Kiwiburger]

An active DI wouldn't work backwards - and a passive DI would still be too hot.

Use a reamp box!

[TonyBelmont]

Originally Posted by Kiwiburger

An active DI wouldn't work backwards - and a passive DI would still be too hot.

Use a reamp box!

What are you talking about? I use Countryman and BSS DI's all the time with keyboards, MPC's and even line level DJ mixers and plug the DI out into the mic preamp's mic input... This is what they are made to do. This isn't that complicated folks!

[Kiwiburger]

OK ... I guess it depends on your interpretation of "Line Level". I was thinking +4 balanced. But yeah - if you mean basically unbalanced instrument level, get a DI box.

[TonyBelmont]

Originally Posted by Kiwiburger

OK ... I guess it depends on your interpretation of "Line Level". I was thinking +4 balanced. But yeah - if you mean basically unbalanced instrument level, get a DI box.

As long as you connect it with an unbalanced cable, you should be good..

[Firefox]

Originally Posted by joeq

not cheap but it's red

sweet!