Integrating Bluetube Pre into DAW

T

theseus75

New member
Hello,

I just bought a Presonus Bluetube pre-amp to add to my DAW. So now I have a Rode NT1A going to the Bluetube into a Presonus Firebox audio interface into an iMac (using Twisted Wave for recording and the initial editing).

I have a few general questions about integrating the pre.

1. Right now I have the input gain on my audio interface turned about 3/4 of the way up, and my pre about half way. Should I reduce the gain on the audio interface and increase it on the pre, vice-versa, or does it even matter at all?

2. Is there a problem plugging/unplugging things while the equipment is powered on? Such as switching a mic from one channel to the other, etc?

3. What would happen if I used phantom power (48v) on both devices? Is there one in which I should use it instead of the other?

4. I'm getting a slight, rhythmic thrumming now that's basically imperceptible except when looking at it with the spectral analyzer and grabbing room tone. It's obvious it's coming from the equipment, not, say, traffic or the AC. Obviously, I'd rather NOT have it, but if I can't even hear it with the volume jacked way up and wearing cans, then does it really matter?

Thanks for the help!
 
Hey man, unless i'm mistaken the Firebox has some line inputs on the back right? if so, to answer your first question; plug the Bluetube straight into one of the line inputs on the back of the firebox rather than into the combo jack/xlr on the front. the whole point of having an external preamp in a setup like this is often to completely bypass the internal pre's on the interface. By plugging your bluetube preamp into another preamp you are double amping the signal and adding nothing but noise. Having the bluetube straight into the line in, the only gain you'll need to set and adjust is the one on the blue tube.

2) It depends what equipment. As a rule of thumb, if i'm swapping a mic i make sure the volume/gain is turned completely down and turn off phantom power (if in use) before unplugging or plugging in a different mic. I'm sure there's more rules than this in theory but in 15 years of doing this i've never had a problem

3) In my head i seem to think there wouldn't be a problem if you have the bluetube plugged into the line in on the back rather than combo mic/line on the front. That way the phantom power on the bluetube would power whatever mic is plugged in to it and the firebox can power another two mics plugged into the mic in's at the front. If you turn them on both in series (i.e if the bluetube is connected to the mic in on the front via an XLR) then there may be some problems, but i've never tried it and i'd rather not do it just in case

4) This may be because you're double amping the signal (i.e it's getting amplified by the bluetube and the preamp on the front of the firebox). try it into one of the line in's and see if that helps
 
Thanks for the reply, JSG. One quick thing: the line input in the back you're referring to - you mean the 1/4 inch jack right? I'll pick up some 1/4" plugs today, give it a whirl, and post back the outcome.

Thanks!
 
yep, those are the ones. Have you been going from the bluetube to the firebox with and XLR to XLR? if so, that will be the cause of most of the problems you were saying about. the combo xlr/jack inputs on the front of the firebox are looking for either an instrument being plugged directly into the jack part, or a mic going into the XLR input. Bare in mind, a Mic actually produces a very, very low voltage itself so the preamp turns it up to a usable volume, where as the output of the bluetube is already amplified to this level so plugging the output of the bluetube into the xlr mic input of the firebox will freak it out as it's expecting to see a tiny signal coming straight from a mic, but instead is being fed a super loud signal and still wanting to amplify it some more.

I ran into a very similar problem with a Motu 8pre a couple of years back. i was using an external pre as i wasn't a fan of the built in ones on the motu so had plugged the output of the external pre into the combo mic/line jack on the the motu, only to find that the jack input didn't bypass the internal pre and the sound was muffled and distorted, even when i had the volume right down on the motu. Long story short, when i bought the interface i have now (Presonus Firestudio Mobile) one of the biggest things for me was to have dedicated line inputs that didn't go through an internal preamp
 
JSG is pretty well on the money.
I have Presonus Bluetube Pre going into an INCA interface sometimes.
I use the direct ins for this and save the preamped ins on the INCA if I need a different flavour for mics etc.
However, I don't often use the Presonus Bluetube. Strangely enough a super cheap Behringer Mic Pre 100 does a better/cleaner job. I use the Presonus when I want a stereo pair of mics so that they match all the way through but otherwise it's a rare thing to use it. I hope yours is better than mine (which is probably just a dud & not a model issue).
 
@JSG - (sheepish) Yeah, I was just running the XLR from mic to pre input one and another from pre to combo jack on the audio interface. I knew there was a wrong way of doing that, but for some reason I was thinking that was in cases in which there was more than one way to plug in your XLRs and some inevitably chose incorrectly. Seeing as there was only one XLR option, I figured I was in the clear. Good thing I asked. I'll swap them out and post results soon.

@Ray - Funny to have you mention the Behringer: I was looking at that, since pssl.com had a smokin' deal on it. I mostly got the Bluetube b/c eventually I want the option to do some stereo work (I'm an audiobook narrator, so it's not likely to come up often, but...). I've heard a pretty wide range of reviews on the BT, and frankly, I wouldn't have bought it new. I got it used on eBay for a pretty good deal, else I would have held out.
 
theseus75 said:
@JSG - (sheepish) Yeah, I was just running the XLR from mic to pre input one and another from pre to combo jack on the audio interface. I knew there was a wrong way of doing that, but for some reason I was thinking that was in cases in which there was more than one way to plug in your XLRs and some inevitably chose incorrectly.
Click to expand...

Dude, don't worry about it man! there's no need to be sheepish, we've all made mistakes and we will all continue to make mistakes in some way or another. the charm of forums like this is often you find someone who has made the mistake you've made and they can tell you what they did to overcome it, and once you know you don't do it again. it's all just learning man. My most recent clanger was not realising that my new audio interface has a Main output knob on it and was panicking like mad when my speakers didn't work and i couldn't see why; i could see the sound in logic playing, i could see the sound in the presonus universal control, i checked the speakers worked with a CD player, i changed the cables from the interface incase it was those, i checked the headphone output and that worked.... 45 minutes, some reinstalled drivers, all my cables, and two phonecalls to mates who have the same soundcard (who were both no help!) and as i was about to google it i suddenly saw this pot on the front of the box marked "Main Out"....... and all i had to do was turn it slightly to hear a shed load of sound :facepalm:

And that's just the most recent example :D

Hope the line input's help (it really should)

@Ray - have you ever A/B the Behringer Mic Pre 100 against the ART Tube MP? For very similar products i'd be intrigued to see how much difference, if any, there is between them
 
JSGuy,
Sorry mate, I don't have the ART to compare with my Behri.
I've also note the Behri's phantom power seems to be a little better than the BT.
Oh, I bought my BT 2nd hand as well & for essentially the same reason - not long after Behringer brought out the next mic pre MIC2200 stereo, rack mounted and still as cheap as chips...
 
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