Pages: [1]   Go Down
  Print  
Author Topic: Firebox, Preamp issues, resolution?  (Read 1280 times)
arriflex
Member
**
Offline Offline

Posts: 43




Ignore
« on: August 22, 2009, 03:24:15 AM »

So I bought a firebox and an SM58 today- turns out low output ribbon mics like the SM's require an external preamp with the firebox.

The solution, apparently, is to get a condenser mic.

So, the question is, what's a decent, but affordable condenser?

Dunk N Donuts, Coffee, and Clayton Ultex picks to all who chime in :)
Logged
rockhound
Senior Member
***
Offline Offline

Posts: 188




Ignore
« Reply #1 on: August 22, 2009, 10:20:15 AM »

I have a MXL 990S - I haven't done much with it yet, but seems pretty good given the price.
Logged

2007 Larrivée L-03R
2008 Tanglewood TW66
1992 Fenix D-90SR
2006 Fender American Telecaster
2007 Schecter C-1 Exotic Star (w/ Bare Knuckle Black Dog pups)
2003 Yamaha RGX420
ronmac
Gold Member
****
Offline Offline

Posts: 4051


WWW

Ignore
« Reply #2 on: August 22, 2009, 12:03:39 PM »

First off, the SM58 is a dynamic mic, not a ribbon mic, and should work OK with the Firebox.

The Firebox has a gain of 45dB, not great, but you can boost it another 12dB in the included utility (see page 9 of OM) and that should be adequate.
Logged

Ron

arriflex
Member
**
Offline Offline

Posts: 43




Ignore
« Reply #3 on: August 22, 2009, 01:52:52 PM »

The 12db of gain is software gain, and presonus has documents on it's site specifically saying the SM57/58 doesn't have enough output to get a good signal with the firebox. We're talking preamps cranked, 12db checked, and it's barely tickling the meters in Logic or Record.

If you google this I am not in the minority- this is common.

"http://psfaq.presonus.com/index.php?action=artikel&cat=20&id=134&artlang=en

FIREBOX
ID #1133
Why can't I get enough gain from my FireBox pre's with my SM58?
In order to keep the FireBox in compliance with IEEE 1394 powering standards, the voltage rails were reduced, which resulted in a slightly lower preamp gain than the preamps found in other PreSonus preamps. The FireBox has approximately 45 dB of analogue gain with an additional 12 dB via the boost for a total of 57 dB total gain. This is sufficient for the majority of the FireBox's users' needs. However, in situations where a low output microphone is used, quiet sound source is recorded, or very hot digital signal is required, it is recommended to pick up an external preamp (like the BlueTube DP, Tube Pre, Eureka, ADL 600, etc) and use it through line inputs 3 & 4.


Take for example the Shure SM58. Based on its specifications, a 94 dB signal into the microphone will result in an output signal of -54 dB. (90 dB is roughly equivalent to the volume of a blender.) So if you record something as loud as a blender with an SM58, the result would be a maximum attainable signal level of +3 dBV (or -15 dBFS). An SM57 has an even lower output (-56dBV/Pa) and would result in a maximum signal level of approximately +1dBV. Conversely, the Shure KSM27 condenser microphone has a sensitivity of -37 dB/Pa. This gives a preamplified signal of +20 dBV (or +3 dBFS) -- a signal roughly 30 times louder than that of the SM58.
Tags: -
"




So, I am going to get a condenser and try that before buying another preamp.
Logged
ronmac
Gold Member
****
Offline Offline

Posts: 4051


WWW

Ignore
« Reply #4 on: August 22, 2009, 02:25:19 PM »

Personally I would ditch the preamp.... Any company that recommends you buy an external preamp to feed their preamp would never get my support.
Logged

Ron

arriflex
Member
**
Offline Offline

Posts: 43




Ignore
« Reply #5 on: August 22, 2009, 02:44:25 PM »

There isn't much in the way of alternatives in that price range. The A/D converter sounds great- this no latency monitoring works perfectly, and my other gear sounds great through it. I'll try the condenser and let you know how it comes together.

I've tried the maudio gear that is priced similar and it sounded poor.
Logged
arriflex
Member
**
Offline Offline

Posts: 43




Ignore
« Reply #6 on: August 23, 2009, 03:55:42 AM »

OK, trials and tribulations continue- decided to stay with the SM58 as I would have needed two condensers to do what I wanted, and I wanted ot mic cabs occasionally.

Went to GC and bought a TubePre, still dont get -CENSORED- for signal off the SM58. Beginning to think it's the SM58. Furthermore, I wanted to swap the crappy tube with one of my decent tubes, and a couple of the screws were stripped out on the TubePre, right out of the factory. The only plus is I got GC to pricematch some online company, so I bagged the TubePre for $99.

I'm dragging everything down to GC with my MacBook Pro tomorrow to sort this out. Definitely going to exchange the TubePre, test the new one with a different SM58 and the FireBox, see where I get.

What started out as a $300 way to lay down sketches at home is starting to grow out of control.
Logged
rockstar_not
Gold Member
****
Offline Offline

Posts: 2310


WWW

Ignore
« Reply #7 on: August 23, 2009, 11:29:54 PM »

I've used all kinds of dynamic mics with my FireBox.  You shouldn't have any difficulty moving meters with the SM-58.  Sounds like a bum SM-58.  Have you used it anywhere else successfully recently?
Logged

2000 L-03-E
2012 Epiphone Nighthawk Custom Reissue
1985 Peavey Milestone
2004 SX SPJ-62 Bass
2008 Valencia Solid Cedar Top Classical
2015 Taylor 414ce - won in drawing
2016 Ibanez SR655BBF

My Sound Cloud
arriflex
Member
**
Offline Offline

Posts: 43




Ignore
« Reply #8 on: August 24, 2009, 12:47:46 AM »

RSN, it's a brand new SM58.

Where is your gain usually set with your SM58?

K
Logged
rockstar_not
Gold Member
****
Offline Offline

Posts: 2310


WWW

Ignore
« Reply #9 on: August 24, 2009, 01:21:39 PM »

RSN, it's a brand new SM58.

Where is your gain usually set with your SM58?

K

Sorry to mislead you.  I don't have an SM-58.

What I do have and use for dynamic headphones:  Sennheiser MD-421, Electrovoice SRO-RE11 and a TEAC MC-105 (probably from the late 60's early 70's)

Sensitivity of the SM 58 is better than the RE11 and TEAC MC-105 according to specs posted on-line (I don't have a manual or spec sheet for the SRO-RE11 - it's pretty ancient)

I haven't had issue with vocals for either the EV or the TEAC microphone, or the MD421 for that matter.

I use a condenser with my Larrivee just because I like the sound so much better than a dynamic mic on it.  I've never bothered with the dynamic mics and the Larrivee because with my CAD M-177 condenser, I just like the sound.

What source material are you trying to use?  Also, have you tried using the wall-wart power supply with the FireBox - that may help to provide enough rail voltage for the pre-amp circuit.

I have had issues with the Firebox with some bleed-over from the output circuitry to inputs (with no outputs plugged in - no headphones, no monitor speakers, nothing).

-Scott
Logged

2000 L-03-E
2012 Epiphone Nighthawk Custom Reissue
1985 Peavey Milestone
2004 SX SPJ-62 Bass
2008 Valencia Solid Cedar Top Classical
2015 Taylor 414ce - won in drawing
2016 Ibanez SR655BBF

My Sound Cloud
Pages: [1]   Go Up
  Print  
 
Jump to: