Preamp input load... Andy? James?

[Glenn Fricker]

I'm just curious if what you guys set your preamp input load for when recording guitar. I was reading the latest issue of Recording and there was a mod for an in-line 'gizmo' to lower the impedance of the preamp before the mic... in this case, an sm57. Apparently, it made a huge difference.

Well, as it turns out, I've got selectable impedance on my preamp. I can go from 1200 ohm to 300 ohm. The manual recommends the 300 ohm setting for ribbons & "certain dynamics." I'm curious if you guys mess around with that stuff, and how so.

-0z-

 

[unsilpauly]

I'm just curious if what you guys set your preamp input load for when recording guitar. I was reading the latest issue of Recording and there was a mod for an in-line 'gizmo' to lower the impedance of the preamp before the mic... in this case, an sm57. Apparently, it made a huge difference.

Well, as it turns out, I've got selectable impedance on my preamp. I can go from 1200 ohm to 300 ohm. The manual recommends the 300 ohm setting for ribbons & "certain dynamics." I'm curious if you guys mess around with that stuff, and how so.

-0z-

great question, i wonder about this as well.

 

[chadsxe]

I have the same options avaiable to me in my Great River MP-2NV. I was playing around with it on vocals the other day and this is what I noticed.

1. I am getting a little extra gain from. Which actually helped me a lot with my SM7. I had a track the required whispering in the background. Needless to say the SM7 requires a lot of gain. I had the GR's input and output gain maked along with the load. THis barely game me enough of a healthy signal.

2. As far as tonal diffrence I think it opens up the "air" quality. Which would give high frequincey boost. Depending on the cab, mic, & guitar, amp etc.. this could be a good thing or a really bad thing.

 

[A Gruesome Discovery]

Setting the impedance higher is essentially the same as introducing an inline mic pad (likely the gizmo cited in that article). Your mic signal will be attenuated by a certain dB amount, but this also greatly increases the headroom on your pre's input, so you can drive it a lot harder, and it will also have major tonal effects, though the nature of such effects rely on a number of factors (mic, pre's input transformer, etc). Low impedances are good for quieter sources (or low-output mics), but this makes it easy to clip your pre's input (a common problem with vintage preamps when used with modern-day, high-output condenser mics).
The most common suggestion I've heard is to try to use 10 times the output impedance of your mic as a starting point, which would be about 1.5k-ohm with a 57, but of course that's hardly a rule; it just supposedly produces the most "neutral" tone for your mic.
I too would like to hear James' or Andy's take on this, or if they even consider impedances at all aside from "padding when needed".

 

[Glenn Fricker]

I have the same options avaiable to me in my Great River MP-2NV. I was playing around with it on vocals the other day and this is what I noticed.

I've got the Mp2NV as well. I tried it out yesterday, and when kicking in the impedance switch (bringing it down to 300 ohms), there'll be an immediate increse in level. The trick is to record two separate takes & match the levels as close as possible. What I'm noticing is the bottom end jumps around a whole lot less & the mids take on a 'velvet' type of quality.

Pretty cool, IMO, I'd just like to get a little more feedback on this one, tho.

-0z-

 

[STINNETT]

I have heard that a 57 "works" best with 600 ohm input impedance. I think I have also settled on this myself after experimenting with the variable impedance on my pre. Like you said, it's got an overall tighter and smoother sound. I suppose you just have to look at it as another option when fishing for your sound.

 

[chadsxe]

I've got the Mp2NV as well. I tried it out yesterday, and when kicking in the impedance switch (bringing it down to 300 ohms), there'll be an immediate increse in level. The trick is to record two separate takes & match the levels as close as possible. What I'm noticing is the bottom end jumps around a whole lot less & the mids take on a 'velvet' type of quality.

Pretty cool, IMO, I'd just like to get a little more feedback on this one, tho.

-0z-

I messed around with it again. I made the levels the same this time around and recorded a quick scratch track to compare and contrast. It really does control the low end a lot more then I noticed (mainly because I was recording vocals last time). All in all I would have to say it starts to smooth out the bottom and hype the really high stuff. I can't express how much I love this pre.

 

[Glenn Fricker]

Kick in the "loading" switch & it'll tame the hi end.