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Double Bass mic and preamp suggestions

lowEndRick

lowEndRick

Apr 8, 2006
406
60
CT
#1
My setup includes a rev solo II, a genz shuttle 6.0, and a schroeder 12. I want to use a mic for some of my smaller, more intimate gigs, but I can't seem to get the volume (or should I say gain) high enough with a mic. I have an Audix D2 and an SM57 to choose from.

I was thinking of using what I have (a Baggs Para DI) to boost the mic signal. Would that work well? Should I go into the input of the Genz or the effects loop? Would the FDeck HPF Preamp be an appropriate tool for this application? Other, better solutions?
 
#2
Hold on a minute, you are dealing with 3 different issues which I don't think you have identified yet.

1. The output of your mics is balanced and nominally about -50dBu but the input of your amp is unbalanced and with a sensitivity of about -20dBu.

2. The output impedance of your mics is about 150 ohms and the input impedance of your amp is about 1meg ohms.

3. You haven't yet reached the other likely limiting factor which is acoustic gain before feedback.

The proper solution is a real mic preamp that provides at least 30dB of gain and has a balanced input with an unbalanced output. This will take care of #1 & 2 . You will then have to deal with #3.

Another possibility, but I don't think it will be satisfactory is to use a balanced to unbalanced impedance matching transformer which offers some voltage gain as a result of the impedance transformation. My assumption is that you are using a simple XLR to 1/4" adapter which will not work the same.
 
#3
lowEndRick said:
My setup includes a rev solo II, a genz shuttle 6.0, and a schroeder 12. I want to use a mic for some of my smaller, more intimate gigs, but I can't seem to get the volume (or should I say gain) high enough with a mic. I have an Audix D2 and an SM57 to choose from.

I was thinking of using what I have (a Baggs Para DI) to boost the mic signal. Would that work well? Should I go into the input of the Genz or the effects loop? Would the FDeck HPF Preamp be an appropriate tool for this application? Other, better solutions?
Click to expand...

Rick,
Well, you could certainly do that but the Para DI is really designed as a piezo pre amp, so I doubt if it will sound all that great as a mic pre.
Running the Audix D2 into one of those line matching transformers will also screw with the sound.
Personally, using a mic into an amplifier in close quarters like your thinking about doing is fraught with peril
because you it's going to feed back. The best mic for this kind of thing is the ATM SP25B (and I have a DPA 4099B!!!)
You'll often find them in the TB classifieds for @$350.00. Well worth it IME, IMHO as they work well with an amplifier.

Ric
 
#4
Thanks for the advice. I have a bigger, outdoor festival gig tomorrow so I think I will try using the Baggs with the rev solo II. Curious to see how that sounds. Should I go to the input or the effects loop? I am about 95% satisfied with my sound with the p/u, but if I can remove some of the edge-iness of the p/u sound with the baggs that will be a victory.

For the next smaller gig which is likely to be a 200 seater or so I am going to try mic'ing without any preamp. But after reading some info on another site I realize I haven't really experimented enough with mic placement. If that doesn't improve things I may look for a specific mic preamp.
 
#5
Hey Rick,

Have you tried placing your mic closer to the ff hole? We spoke recently about this and you said you were pointing it at the table under the fingerboard?

You'll definitely get more juice toward the opening, but I expect that may introduce more feedback potential.

I just dug this out of my bin and dusted it off, trying to solve what is basically the opposite of this problem:
http://www.buy.com/prod/presonus-tubepre-microphone-preamp/203474345.html?listingId=204730903
It adds stoopid gain if you want it to. You're welcome to borrow it if you like, though the low impedance may be an issue.
 
#6
I haven't been getting enough volume at or near the ff hole. I recently tried placement in the space between the bridge and the end of the fingerboard and it sounded louder, but this wasn't at a venue or performance space where I could really test the volume. This will be my next step.

Tomorrow all bets are off. A 7 piece band with a drummer at a tented festival. There's no way I am taking any chances with a mic. :rollno:

just saw ur edited mingus... thx, i'd love to try that preamp. maybe in october sometime.
 
#7
lowEndRick said:
I haven't been getting enough volume at or near the ff hole.
Click to expand...
Wow. I never would've thought.

lowEndRick said:
I recently tried placement in the space between the bridge and the end of the fingerboard and it sounded louder, but this wasn't at a venue or performance space where I could really test the volume. This will be my next step.

Tomorrow all bets are off. A 7 piece band with a drummer at a tented festival. There's no way I am taking any chances with a mic. :rollno:

just saw ur edited mingus... thx, i'd love to try that preamp. maybe in october sometime.
Click to expand...
Cool. Lemme know. I may wind up needing it myself but only if I don't figure something better out. It turns out I think I was wrong -- Mark Schatz didn't blow the speaker -- rather my pickup signal is super hot going into the AI. :o
 
#8
lowEndRick said:
For the next smaller gig which is likely to be a 200 seater or so I am going to try mic'ing without any preamp. But after reading some info on another site I realize I haven't really experimented enough with mic placement. If that doesn't improve things I may look for a specific mic preamp.
Click to expand...

Have you tried it without a preamp and were you able to get adequate level? You might want to try this in a non-gig situation first, that way you won't embarass yourself in front of an audience or add to the stress level of the gig..

I suggest that you might want to do some reading on level and impedance matching... your mic is not going work well with your amp without a (properly configured) preamp. I designed your amp, I have a pretty good idea of what will and will not work. It will make some sound, but not very much and the noise floor would be IMO objectionable.
 
#9
agedhorse said:
Have you tried it without a preamp and were you able to get adequate level? You might want to try this in a non-gig situation first, that way you won't embarass yourself in front of an audience or add to the stress level of the gig..

I suggest that you might want to do some reading on level and impedance matching... your mic is not going work well with your amp without a (properly configured) preamp. I designed your amp, I have a pretty good idea of what will and will not work. It will make some sound, but not very much and the noise floor would be IMO objectionable.
Click to expand...

I greatly appreciate your response and advice. Yes, I have tried my Audix D2 mic without a preamp and have not been able to get adequate level. I might need to try different mic placement, or maybe I just need a preamp as you suggest. Do you have any recommendations for mic preamps?
 
#11
agedhorse said:
Hold on a minute, you are dealing with 3 different issues which I don't think you have identified yet.

1. The output of your mics is balanced and nominally about -50dBu but the input of your amp is unbalanced and with a sensitivity of about -20dBu.

2. The output impedance of your mics is about 150 ohms and the input impedance of your amp is about 1meg ohms.

3. You haven't yet reached the other likely limiting factor which is acoustic gain before feedback.

The proper solution is a real mic preamp that provides at least 30dB of gain and has a balanced input with an unbalanced output. This will take care of #1 & 2 . You will then have to deal with #3.
Click to expand...

Agree with the above. I'll take the numbers at face value as I don't truly understand them, but the advice is spot on. If the signal chain doesn't give you the best possible match going in, everything after that will be garbled. As for #3, I have three articles about using mics onstage [Invalid or Expired Link Removed]. Mic placement is only one part of the equation once you solve the electronic matching equation. The other big issue is making sure your mic placement corresponds to a workable speaker placement; the relationship of these two is (IMO) the biggest factor involved in getting volume before feedback.
 
#13
Chris Fitzgerald said:
Agree with the above. I'll take the numbers at face value as I don't truly understand them, but the advice is spot on. If the signal chain doesn't give you the best possible match going in, everything after that will be garbled. As for #3, I have three articles about using mics onstage [Invalid or Expired Link Removed]. Mic placement is only one part of the equation once you solve the electronic matching equation. The other big issue is making sure your mic placement corresponds to a workable speaker placement; the relationship of these two is (IMO) the biggest factor involved in getting volume before feedback.
Click to expand...

Absolutely. It's a complicated subject if you are going after the very best possible performance. Off axis frequency response uniformity is another often neglected parameter that affects performance.
 
#18
Ric Vice said:
Rick,
Well, you could certainly do that but the Para DI is really designed as a piezo pre amp, so I doubt if it will sound all that great as a mic pre.
Running the Audix D2 into one of those line matching transformers will also screw with the sound.
Personally, using a mic into an amplifier in close quarters like your thinking about doing is fraught with peril
because you it's going to feed back. The best mic for this kind of thing is the ATM SP25B (and I have a DPA 4099B!!!)
You'll often find them in the TB classifieds for @$350.00. Well worth it IME, IMHO as they work well with an amplifier.

Ric
Click to expand...



you really like that mic better than the dpa? i had the atm, but sent it back during the trial period. actually i took it back since the manufacturer is near my house...
 

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