Red-Eye Twin Routing

[John Flynn]

I've noticed there are some long term Red-Eye users and some real sound reinforcement exerts here. I just got my Red-Eye Twin and it sounds great. I have a couple of questions I would appreciate advice on. Let me say that I am no sound expert and I may misuse some of the terms.

First, I found that when I went into my Crate CA-30 (the older model) using the Red-Eye XLR output through an XLR cable with a low-to-high impedance transformer at the end, the resulting volume was about 50% louder than going through the effects out with a 1/4" cable with the same Red-Eye and amp settings. Is that because XLR is that much more efficient, even with the transformer, or is it that the Red-Eye XLR out is a hotter signal?

Second, I play every week with a large church choir. I have to go into the sound board through a remote junction box (my term) that only has 1/4" plugs. I use the Crate amp as a personal monitor just so I can hear myself because it's a big group. So I can see two ways to do my cable routings:

Red-Eye XLR out >>>Lo-to-High Transformer>>>Crate>>>Crate Line Out>>>Junction Box

OR...

Red-Eye XLR out >>>Lo-to-High Transformer>>>Junction Box
Plus
Red-Eye effects out>>>1/4" cable>>>Crate amp

So this is my big question: Would running the Fire-Eye signal through the Crate degrade the sound quality that gets to the board? The first option gives me some more EQ control and is more convenient, but I don't want to do it if it going to "dumb-down" the great sound coming out of the Red-Eye that gets to the board.

[Chunky But Funky]

Hi John,
If I'm understanding the situation correctly, it seems as though you are doing the reverse of what you would want to do at the junction box. The Red-Eye has a low impedance, XLR out so as to maintain as much of the signal as possible through a long cable run (through the snake to the board - for example). Converting it back to high impedance essentially negates some of the benefits of the low impedance XLR out. Are you sure all you don't need is a plug and / or gender changer? Most stage boxes have XLR inputs for mics and the outputs of DI boxes. If you are out of XLR spots on the stage box, there are sometimes XLR or 1/4" returns (designed to send the monitor signal back to the stage from the board). If there are free male XLR connections, all you need is a gender changer at both ends. We have needed to do this for my son's band at times. If they are 1/4", are you sure they are not balanced? If there are you just need an XLR to Balanced (TRS) 1/4" connector and not a transformer. That would keep it balanced and low impedance throughout the signal path. I hope this didn't cause more confusion than it solved!!!

Doug

[Chunky But Funky]

John,
As for the second part of the question, I would probably opt for #2 if it were me. That gives you and the person running sound the signal that is closest to the original. The eq requirements may be very different for your stage monitor and FOH. However, that also doesn't account for the skill / experience level of the person behind that mixing board (as we both discussed in the previous thread re: pick-ups vs. mics). Hope it helps a little bit anyway!

Doug

[John Flynn]

Doug

Thanks for your thoughtful replies. I have asked about the input thing, but I will ask again. The way it has worked is the sound guy just hands me a 1/4" two-connector cable and I plug it into my gear. He says there are no XLRs available, but perhaps if I phrase the question as you have and do a little more poking around, I can get a different answer. I am also thinking about running my own XLR cable to the board. It would be 20-30 feet, but it might be worth it. I imagine each channel on the board has an option of either/or.

As to the skill/experience of the sound guy, I think it's moderate. He's an accountant by trade and a singer in the choir. I think he was originally trained as an engineer, not sure what kind. He knows the church's system like the back of his hand and he's pretty good with microphones, but I'm not sure he knows as much about the big sound reinforcement world and he doesn't think "out of the box." Also he's not really an instrumentalist so he doesn't really get that side of the equation.

[almeriastrings]

Red-Eye XLR out >>>Lo-to-High Transformer>

OR...

Red-Eye XLR out >>>Lo-to-High Transformer>>>Junction Box
Plus


All you are doing there is linking two transformers. One is the internal High-Low transformer in the Red-Eye, the other the external Low-High.... this will work, in the sense that the signal still passes, but is not a good idea. It certainly adds some distortion, for one thing. May not be audible - but it is there. Despite the perceived 'increase' in volume, there are in fact also extra losses involved. These are comprised of both core losses and winding losses. The exact performance is also affected by the turns ratio. In short, this is adding in extra distortions and losses for no benefit. How precisely it will perform in terms of perceived volume is also highly dependent upon the load the amplifier input stage presents. So, on some amps you might experience it 'louder' like this, or 'quieter' - it entirely depends on how that particular combination interacts and behaves. None of that changes the fact that it is still not a good idea.

Not sure what the 'junction box' is - but if it is a typical stage box it will have XLR input sockets. You should plug the Red-Eye's XLR out straight into one of those. If it only has 1/4" Jack sockets, these are likely non-TRS, standard unbalanced inputs designed for guitars or keyboards. In this case, use the FX loop output from your Red-Eye.





Red-Eye effects out>>>1/4" cable>>>Crate amp



Simple answer to that. You should not be using a preamp at all prior to the Crate. The Crate already has a 1.5M Ohm high impedance input designed for direct connection to acoustic instruments. No other preamp required. You are just introducing extra components to no benefit at all. You can then feed the line out from the Crate direct to the PA. There is no point at all in 'stacking' preamplifiers like that that. More noise. More distortion. Very poor impedance matching (the FX loop out on the Redeye is 4K). If you look, furthermore, at the block diagrams on the Red-Eye's website you will see that the FX loop merely bypasses one thing: the output transformer.

http://www.fire-eye.com/red-eye-twin_data_sheet.htm




So this is my big question: Would running the Fire-Eye signal through the Crate degrade the sound quality that gets to the board? The first option gives me some more EQ control and is more convenient, but I don't want to do it if it going to "dumb-down" the great sound coming out of the Red-Eye that gets to the board.


This is actually quite complex. First, the Red-Eye is not actually a "pre-amplifier" in the normal sense at all. It is an impedance matching buffer unit that attenuates the input to output by a substantial amount. Their figures:

"From the Instrument Input to the Effects Output the gain is -1 db. (In other words the output voltage level is 80% of the input)

From the Instrument Input to the Balanced XLR Output, the gain is -5 db. (In other words the output voltage level is 33% of the input)"


It only acts as a pre-amplifier if you engage the 'boost' control. Without it, it is a "pre-attentuator", not a "pre-amplifier"!

It also has a "tone" control (treble only). All "tone" controls and EQ's introduce some degree of phase variance. May be miniscule and near undetectable, but it will be there to some degree. Building very high quality complex EQ's is difficult. That is why high-end studio EQ's (Pultec, Manley Passive, etc.,) can cost multi-thousand $$$. The EQ in the Red-Eye is very basic so probably does what it does well. The Crate has a more complex EQ, so will have more "character" and sonic impact. It will be more 'colored' than the output from the Red-Eye simply because it has a far more complex, and higher gain design. I am not familiar with the CA30 in detail, but if you can bypass the EQ and leave any FX off, that will result in the cleanest possible feed from its line output. The actual input stage is very decent and is a very good match to most transducers.

One thing you have not said is what you are sending to the Red-Eye or Crate? Passive transducer? Active pickup system?