Building a MIC/LINE switching box

[Tomasz]

I have several pre-amp, compressor, E.Q. "strips" that I'd like to be able to run with LINE signals. Some of my pres have mic/line inputs and switches built in, however some do not. I'd like to build a project box that houses xlr input jacks for my mic and line signals switchable via a toggle and a common xlr output. I'm not sure if i'd need anything besides this, ie; resistors, etc.
They have boxes for this, such as the kramer 4X2, but I'm thinking i gotta be able to build this for considerably less. I'm also figuring some sort of line "PAD" option that Avedis electronics makes for this very concept, or the D.W.Fearn line pad box, would be a good idea.
Any thoughts on this are greatly appreciated..
Thanks engine ears...
tomasz

[Mixwell]

Sounds like a simple passive switcher box would work well. I use ours for switching mic and line signals all the time. The Fearn LP-1 uses an L type bridging pad with the highest quality jensen transformers.

I haven't used the Avedis, but the LP-1 is great, and is meant to accompany the VT2, so you can run your mixes through it and "toast" the audio to a golden brown texture. It also works well for sending +4 signals into any preamp.

The Shadow should be able to answer the technical questions easily. I'd say this won't be very hard once you have the idea stamped into place.

[Tomasz]

Just as I suspected, Adam. Thank you. I will now await some technical ecstasy: as in specific toggles, etc..

[the shadow]

If you plan on using one input at a time your cheapest and most direct method would probably be a 2 or 3 section rotary switch. You could use another rotary switch for the outputs as well. If you post some details on the exact gear you want to use I can probably draw something up.

[Tomasz]

If you post some details on the exact gear you want to use I can probably draw something up.

Shadow, Thank you for your reply.
Here are the details: I have 4 Mic pres.(Great River MpNV series) ALL with one input only. I keep the outputs patched directly to my AD converters. I'd like to be able to "add" Line inputs to the pres: So I need input switching. I planned on two panel mount input XLR jacks and one panel mount XLR output per pre, mounted in a rack mounted project box. Rotary or toggle switch is fine, and two way, ie; Mic or Line is all I need unless you suggest a 3 position, with the 3rd position wired to nothing as in an "input mute" position. Cheap is really not a concern, but high quality components ARE. I'd prefer my mind to be at ease knowing I have not added anything to the signal chain that could be detrimental. Some brand or manufacturer recommendations on the switches would be appreciated, as the toggles I've seen locally at hardware store do not meet my standards in feel or build quality, and hence most certainly not up to snuff for passing audio to gear of this caliber.
Thank you very much.
Tomasz

[Dan]

Why not just use a half-normalled patchbay? Keep your mic signal normalled to the input of the preamps, but patch in the line sources as necessary.

-Dan.

[Tomasz]

Why not just use a half-normalled patchbay? Keep your mic signal normalled to the input of the preamps, but patch in the line sources as necessary.

-Dan.

Thank you Dan.. absolutely correct however, a few reasons for it.
One: My pres outputs are already half-normalled to my AD and i'm outta room. Plus I don't really like the idea of Mic lines through a bay. i know this is standard practice at pretty much all REAL studios, but I like the mic lines as direct as possible. ( we do not need to debate any merits of this) And I can't really afford another patchbay, nor do i want one at the moment as this would mean a big expense in the bay itself, and all the cabling. probably exceeding 1500 samolians.... I am teetering on the edge of soon having to do this, however, right now I'd rather have a few other choice pieces of gear.
Two: I want to build this. It should be an enjoyable experience that will accomplish my goals with what i think will be a minimal cash outlay.

And Dan, certainly i will eventually be taking the route you suggested, ( I still love crawling behind all my rack gear:rolleyes:) but for now this will fill my needs and be a great learning experience, and will help streamline my setup..

[the shadow]

If you have a patchbay with 4 spare inputs and 4 spare outputs you could wire 4 pads input to output and have the flexability to connect any line input to any mic pre input you have or might get in the future. If you want to use an xlr panel and switches you need double pole double throw switches(one per preamp). C & K toggle switches are not too bad. If you want rotary switches Elma switches are good(they are found in most Neve modules). You could wire the pad between the line input and the switch. I would also add some blocking caps at the line input to prevent phantom power from causing any damage.

[Tomasz]

Thank you shadow... I may hit you up for a few more suggestions/ advice soon..