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Checking a mic preamp without connection to audio interface
If you have a powered mic preamp connected to a mic via an XLR cable but with no further connection to an audio interface (that would typically be via a balanced 1/4" jack pickup cable), shouldn't the VU meter on the channel output level of the preamp become active when the preamp is turned on, the mic is powered with 48V phantom power, and the output level knob for the channel the mic is connected to is turned?
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Doerr Trinity 12 Fret 00 (Lutz/Maple) Edwinson Zephyr 13 Fret 00 (Adi/Coco) Froggy Bottom H-12 (Adi/EIR) Kostal 12 Fret OMC (German Spruce/Koa) Rainsong APSE 12 Fret (Carbon Fiber) Taylor 812ce-N 12 fret (Sitka/EIR Nylon) |
#2
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If I'm understanding you correctly, yes.
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#3
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Jim 2023 Iris ND-200 maple/adi 2017 Circle Strings 00 bastogne walnut/sinker redwood 2015 Circle Strings Parlor shedua/western red cedar 2009 Bamburg JSB Signature Baritone macassar ebony/carpathian spruce 2004 Taylor XXX-RS indian rosewood/sitka spruce 1988 Martin D-16 mahogany/sitka spruce along with some electrics, zouks, dulcimers, and banjos. YouTube |
#4
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#5
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But the VU meters work on mine regardless if the pre is connected to an interface or not.
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Enjoy the Journey.... Kev... KevWind at Soundcloud KevWind at YouYube https://www.youtube.com/playlist?lis...EZxkPKyieOTgRD System : Studio system Avid Carbon interface , PT Ultimate 2023.12 -Mid 2020 iMac 27" 3.8GHz 8-core i7 10th Gen ,, Ventura 13.2.1 Mobile MBP M1 Pro , PT Ultimate 2023.12 Sonoma 14.4 Last edited by KevWind; 06-19-2021 at 10:02 AM. |
#6
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What would that VU meter be measuring? Usually it's output (work being done).
Not sure what a VU meter would indicate when current not flowing through it.
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Derek Coombs Youtube -> Website -> Music -> Tabs Guitars by Mark Blanchard, Albert&Mueller, Paul Woolson, Collings, Composite Acoustics, and Derek Coombs "Reality is that which when you stop believing in it, doesn't go away." Woods hands pick by eye and ear
Made to one with pride and love To be that we hold so dear A voice from heavens above |
#7
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So what prompted this is I took delivery on Thursday of a new Sebatron Axis 200 preamp that I purchased from Soundpure as a demo unit.
I connected it to my DAW (Reaper) via my Scarlett 2i4 interface as follows: 1. XLR mic cables from two SDC's (KM184's) to Axis XLR inputs. 2. XLR mic cables from Axis XLR outputs to Scarlett XLR inputs, Scarlett mic gain controls set to 0, Scarlett phantom power off, Scarlett Line/Inst switch set to Line. 3. Scarlett USB feed to PC and DAW setup with two tracks (Channel 1 and 2 on both the Scarlett and Axis). When I power the Axis up, for each channel the Pad/Gain control knob is set to -15dB (full counterclockwise to the left), Output Level control knob is set to 0, HPF is off, phantom mic power is off. When I turn the phantom power on for each mic channel and turn the Output Level knob to the right, there is no activity on the Axis VU meters and no activity on the track level indicators in the DAW. Using same XLR cables from mics to the Axis, if I take the Axis out and go straight to the Scarlett and use it's preamps, everything works fine. I wonder if the Axis is DOA. I'll be in touch with Soundpure first thing on Monday.
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Doerr Trinity 12 Fret 00 (Lutz/Maple) Edwinson Zephyr 13 Fret 00 (Adi/Coco) Froggy Bottom H-12 (Adi/EIR) Kostal 12 Fret OMC (German Spruce/Koa) Rainsong APSE 12 Fret (Carbon Fiber) Taylor 812ce-N 12 fret (Sitka/EIR Nylon) |
#8
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Does the red indicator light come on when you engage phantom power? Short of any of those, I can't think why it would not be working other than the unit being damaged in some way. And since it's a demo unit, that's certainly possible. In the videos on this unit, SoundPure says they have them in use in their studio. A demo from them might have a lot of hours on it.
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Jim 2023 Iris ND-200 maple/adi 2017 Circle Strings 00 bastogne walnut/sinker redwood 2015 Circle Strings Parlor shedua/western red cedar 2009 Bamburg JSB Signature Baritone macassar ebony/carpathian spruce 2004 Taylor XXX-RS indian rosewood/sitka spruce 1988 Martin D-16 mahogany/sitka spruce along with some electrics, zouks, dulcimers, and banjos. YouTube |
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Now that we know that the pre is Australian and you're (probably) American, the only other thing I can think of is that it might be set for 220V operation, when you probably want 110.
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Doerr Trinity 12 Fret 00 (Lutz/Maple) Edwinson Zephyr 13 Fret 00 (Adi/Coco) Froggy Bottom H-12 (Adi/EIR) Kostal 12 Fret OMC (German Spruce/Koa) Rainsong APSE 12 Fret (Carbon Fiber) Taylor 812ce-N 12 fret (Sitka/EIR Nylon) |
#11
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I don’t think this would cause the problem you’re having, but you should connect the preamp output to the Scarlett 2i4 using a 1/4” plug at the 2i4. Using a xlr at the 2i4 runs it into the mic preamp which can handle only a 3.5 dbu max signal (even with switch set to line).
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Chuck 2012 Carruth 12-fret 000 in Pernambuco and Adi 2010 Poling Sierra in Cuban Mahogany and Lutz 2015 Posch 13-fret 00 in Indian Rosewood and Adi Last edited by ChuckS; 06-19-2021 at 09:38 PM. |
#12
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So if everything works by taking the Seb out of the equation then the problem is definitely with Seb I have never used one so just guessing
First are you letting the Pre's tubes warm up ? say 5 or more minutes ? If so ::: #1 what about Bad tubes ???? is there any venting slots where you can see if the tube/s are glowing inside the pre amp (without having to take the cover off) ? It is strange it really almost sounds like maybe the phantom power is not getting to the mic circuit But if the light is on then it should be ??? Have you tried a dynamic mic and see if you get any signal in the VU meter's ???
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Enjoy the Journey.... Kev... KevWind at Soundcloud KevWind at YouYube https://www.youtube.com/playlist?lis...EZxkPKyieOTgRD System : Studio system Avid Carbon interface , PT Ultimate 2023.12 -Mid 2020 iMac 27" 3.8GHz 8-core i7 10th Gen ,, Ventura 13.2.1 Mobile MBP M1 Pro , PT Ultimate 2023.12 Sonoma 14.4 |
#13
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I'll try a dynamic mic but it's a moot point as I record solo guitar with SDC's and LDC's. The more I think about it, something is definetly wrong with this unit. It's going back to Soundpure. At least I have the new Motu interface coming in on Monday to start working with.
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Doerr Trinity 12 Fret 00 (Lutz/Maple) Edwinson Zephyr 13 Fret 00 (Adi/Coco) Froggy Bottom H-12 (Adi/EIR) Kostal 12 Fret OMC (German Spruce/Koa) Rainsong APSE 12 Fret (Carbon Fiber) Taylor 812ce-N 12 fret (Sitka/EIR Nylon) |
#14
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Thanks!
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Doerr Trinity 12 Fret 00 (Lutz/Maple) Edwinson Zephyr 13 Fret 00 (Adi/Coco) Froggy Bottom H-12 (Adi/EIR) Kostal 12 Fret OMC (German Spruce/Koa) Rainsong APSE 12 Fret (Carbon Fiber) Taylor 812ce-N 12 fret (Sitka/EIR Nylon) Last edited by SprintBob; 06-20-2021 at 01:07 AM. |
#15
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Bummer that they didn't test that demo unit before they sent it but at least you have the problem figured out. Kudos to Kevin for thinking of trying a dynamic mic.
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Jim 2023 Iris ND-200 maple/adi 2017 Circle Strings 00 bastogne walnut/sinker redwood 2015 Circle Strings Parlor shedua/western red cedar 2009 Bamburg JSB Signature Baritone macassar ebony/carpathian spruce 2004 Taylor XXX-RS indian rosewood/sitka spruce 1988 Martin D-16 mahogany/sitka spruce along with some electrics, zouks, dulcimers, and banjos. YouTube |