What do I do with this EH mic pre?

  • Thread starter Thread starter Max Mediocre
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Max Mediocre

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So I just got this Electro Harmonix mic pre, and I'm not sure how to use it. I have a firebox, and I plugged it into one of the firebox's preamps, then turned the gain all the way down. Problem is, there's hardly any signal coming through. I can turn the gain up, but then I'm using the firebox's preamp and what's the point of having another preamp at all? Also, I knew there were grounding issues but I thought they were solved by using balanced cables. I'm running a balanced XLR to XLR straight from the EH to the firebox, but I still get an annoying hum that's almost the same level as the signal. Does anybody know what the deal is? I'm not sure if my unit is defective, or if I'm doing something wrong. It sounds good, but I have to digitally boost the gain a huge amount (like 20 db) before I get a reasonable signal, and then that hum just comes up at the same time. I'm using an SM7, which I think is a fairly low output microphone, but the gain on the EH pre is at maximum.

Also, are the tubes supposed to look the same? One of them definitely glows more than the other, I'm not sure if that's normal or not.

Any advice guys?

thanks.
 
You shouldn't be plugged into the pre...go into the Line in on the back of your firebox...

Jacob
 
I don't know about plugging the EH pre's output into a mic input... I think I'd rather avoid running through two mic pre stages. And are you sure the phantom power is off on the firebox?

My EH pre's have a hot output and no problems w/hum. In fact they're remarkably quiet pre's IMO. The tubes do glow differently from one another on mine also.

I use the 1/4" output jack to monitor and use a balanced TRS plug/cable to a balanced input with no hum. Only way I can make them hum is by using the 1/4" output with an unbalanced cable, which I don't think it's designed to use.

Tim
 
I did a search and found the thread about the hum, but I don't think I really understood exactly. So what I really ought to do is get a balanced XLR to TRS cable and run it into the line in on the back of the box? That makes a lot more sense than running two stages of preamp. Thanks guys, I'll try that out once I can get my hands on the proper cable. The preamp itself sounds really nice, just for the record. I was running it at full gain so it was probably saturating the signal a good deal, but that was pretty much what I was going for anyway. I'm pretty satisfied with the actual tone.

One more question: if I run it into the line input, and I want a saturated signal (with the gain knob at max), how do I keep it from clipping digitally once it hits the computer? I guess depending on how hot the signal is it may not be an issue, but I'm curious if this will be a problem.
 
once you get the right cable going, post some examples of your music...I'd love to hear...

Jacob
 
Max Mediocre said:
One more question: if I run it into the line input, and I want a saturated signal (with the gain knob at max), how do I keep it from clipping digitally once it hits the computer? I guess depending on how hot the signal is it may not be an issue, but I'm curious if this will be a problem.
Click to expand...
The firebox manual covers it, page 20. The firebox software mixer enables you to reduce the gain of the cards inputs meaning you can crank the EH pre without clipping the converters.
 
Max Mediocre said:
I did a search and found the thread about the hum, but I don't think I really understood exactly. So what I really ought to do is get a balanced XLR to TRS cable and run it into the line in on the back of the box? That makes a lot more sense than running two stages of preamp. Thanks guys, I'll try that out once I can get my hands on the proper cable. The preamp itself sounds really nice, just for the record. I was running it at full gain so it was probably saturating the signal a good deal, but that was pretty much what I was going for anyway. I'm pretty satisfied with the actual tone.

One more question: if I run it into the line input, and I want a saturated signal (with the gain knob at max), how do I keep it from clipping digitally once it hits the computer? I guess depending on how hot the signal is it may not be an issue, but I'm curious if this will be a problem.
Click to expand...

If you want a saturated signal, the best way to get this with the EH pre is to use the "buffer." For this, you'll need to use the 1/4 inch out, instead of the xlr out. Crank the left knob up to acheive some saturation, then "buffer" the signal volume with the right knob (lower it until you get a suitable signal to avoid clipping your hard disk). This knob combo is similiar to a "pre" and "post" on a guitar amp.

When you use the xlr out, the right knob doesn't do anything - you've probably already noticed this. I'm not sure why the buffer only works when you use the 1/4 inch out instead, but this is the set up.
 
Ben Logan said:
If you want a saturated signal, the best way to get this with the EH pre is to use the "buffer." For this, you'll need to use the 1/4 inch out, instead of the xlr out. Crank the left knob up to acheive some saturation, then "buffer" the signal volume with the right knob (lower it until you get a suitable signal to avoid clipping your hard disk). This knob combo is similiar to a "pre" and "post" on a guitar amp.

When you use the xlr out, the right knob doesn't do anything - you've probably already noticed this. I'm not sure why the buffer only works when you use the 1/4 inch out instead, but this is the set up.
Click to expand...


They do this so that the signal through the XLR is more discrete I believe. The 1/4" is mainly for monitoring purposes in my case, or I guess you could use it as you have explained, but I would rather have my signal not go through the buffer.

The EHX pre, definately needs to be used with balanced cables, whether 1/4" or XLR is doesn't matter as long as they are balanced.
 
Yeah, you're right 4-man. The xlr signal is more pure. I do like the 1/4 output for the ability to crank up the gain though. E.g. "crunchy drums," etc.

Forgot to mention: I love this pre! Biggest bang for my buck yet. Proud RNP owner too.
 
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