how to balance mic gains? tube mic preamp goes into tascam souncard/interface..

[richardosim78]

hey, dears,

i plug mic into tube preamp , and then preamp goes into tascam audio interface(us-122l)..
how should i balance gains of both devices????
how should i avoid using tascam's gain intervention and use more of the preamp's valve-ish gain in the recordings?? i dont get it? should i keep tascam's knob low as hell and pump preamp's gain high as shit??

what r general guidelines for using two or more devices that influence mic's gain in the same chain??????

thank u all!

 

[Farview]

You shouldn't be plugging the output of a mic preamp into the input of another mic preamp.

Doesn't the tascam have line inputs? That is what you should use with the tube preamp.

If it doesn't, there should be some indication of unity gain on the tascam. Set it to unity and set recording levels with the tube preamp.

 

[richardosim78]

You shouldn't be plugging the output of a mic preamp into the input of another mic preamp.

Doesn't the tascam have line inputs? That is what you should use with the tube preamp.

If it doesn't, there should be some indication of unity gain on the tascam. Set it to unity and set recording levels with the tube preamp.

well tascam us-122L is a soundcard with 2 xlr and 2 1/4 jack inputs. and these inputs r driven by tascam level/input knobs..knobs have "line" title on the left and "mic" title on the very right.. its kinda min/max positions..

http://tascam.com/content/downloads/products/312/US122L_E_Web.pdf
unity gain?? ive heard about that. its kinda "neutral" position of a device.. can u explain it more in simple words? i couldnt find that in the manual..

oh and both devices(tascam soundcard and tube preamp) have phantom power. which one in the chain should i use for my condenser mic??
i guess, since tube preamp has its own power adapter and is closer to the mic , i should us it for phantom power. right?
thanks man

 

[mixsit]

http://tascam.com/content/downloads/products/312/US122L_E_Web.pdf
Page 15

And later on page 23 it says how to set it-

Nominal input levels
MIC IN L and R (XLR balanced) –58 dBu (TRIM at max) to –14 dBu (TRIM at min)

MIC/LINE-GUITAR L and R in [with the switch in the] MIC/LINE position (1/4” jack, unbalanced) –40 dBu (TRIM at max) to +4 dBu (TRIM at min)

MIC/LINE-GUITAR R in GUITAR position (1/4” jack, unbalanced) –51 dBu (TRIM at max) to –7 dBu (TRIM at min)

That ' +4 dBu ' is nominal line level, so that's what you set it for.

As for the pre amp, the 'rule is you always want to get your sources- and the first device in a chain optimized. That sets your best signal qualities right off up front, everything down stream (typically) is now just passing that on, doing its job without adding or detracting to it -i.e. in this case passing your line level on to the converter. Farview was just using the term 'unity' that is used to imply that- line in, set it for line in, pass it on.

 

[Farview]

Unity is the gain position that niether adds or takes away any gain. The point is to use the tube preamp to get the signal to line level and have everything else in the chain maintain that level, as was explained in the last post.

You need to use the phantom power on the tube preamp. Always use the phantom power on the device that the mic is plugged directly into. If you turn on the phantom on the tascam, you will be feeding it to the output of the tube preamp, which is pointless.

 

[richardosim78]

http://tascam.com/content/downloads/products/312/US122L_E_Web.pdf
Page 15

And later on page 23 it says how to set it-

Nominal input levels
MIC IN L and R (XLR balanced) –58 dBu (TRIM at max) to –14 dBu (TRIM at min)

MIC/LINE-GUITAR L and R in [with the switch in the] MIC/LINE position (1/4” jack, unbalanced) –40 dBu (TRIM at max) to +4 dBu (TRIM at min)

MIC/LINE-GUITAR R in GUITAR position (1/4” jack, unbalanced) –51 dBu (TRIM at max) to –7 dBu (TRIM at min)

That ' +4 dBu ' is nominal line level, so that's what you set it for.

As for the pre amp, the 'rule is you always want to get your sources- and the first device in a chain optimized. That sets your best signal qualities right off up front, everything down stream (typically) is now just passing that on, doing its job without adding or detracting to it -i.e. in this case passing your line level on to the converter. Farview was just using the term 'unity' that is used to imply that- line in, set it for line in, pass it on.

damn, what a useful info..
pls explain what r these TRIM AT MIN, TRIM AT MAX?? why do u use that TRIM AT MIN value as for that unity gain??? where and how should i set that +4 dBu nominal line level for tascam??

and if i wanna use only xlr cables in the chain , should i use that –14 dBu (TRIM at min) as my unity/nominal gain??????? and again where should i set it??
or should i always look for TRIM AT MIN value of the line level inputs only, and ignore xlr TRIM AT MIN value??

i also read about that: consumer line level is at -10dBV, and professional line level is at +4dBu. so mine is a typical pro line level of +4dBu and that is that damn UNITY GAIN??

thank uuu!

 

[richardosim78]

Unity is the gain position that niether adds or takes away any gain. The point is to use the tube preamp to get the signal to line level and have everything else in the chain maintain that level, as was explained in the last post.

You need to use the phantom power on the tube preamp. Always use the phantom power on the device that the mic is plugged directly into. If you turn on the phantom on the tascam, you will be feeding it to the output of the tube preamp, which is pointless.

yes i get it...

and what if i wanna connect second additional mic straight into tascam and give it phantom power from it? that shouldnt hurt my first mic in the tube preamp, right??

danke!

 

[mixsit]

Sometimes you'll see a single global phantom power switch, but more often there's one for each input. Which does yours have?
And better yet is since you're pre is going 1/4 line in right? Likely there's no phantom power on a TRS, certainly not on a TS jack (again- find out which is yours?

 

[miroslav]

Unless you're using ribbon mics....you don't need to worry about hurting a mic with phantom power.
Ev en if you only use dynamic mics and the phantom is accidentally on....it won't be an issue.

AFA you interface...just by looking at the picture in your post above....it looks to me like the phantom power is either on or off for both inputs.

 

[mixsit]

damn, what a useful info..
pls explain what r these TRIM AT MIN, TRIM AT MAX?? why do u use that TRIM AT MIN value as for that unity gain??? where and how should i set that +4 dBu nominal line level for tascam??

Don't worry about the word 'unity right now. Look at the input volume knobs - see where it says 'Line'? That's your 'trim at min' (although it could be better called 'gain' at min) for line level inputs.

and if i wanna use only xlr cables in the chain , should i use that –14 dBu (TRIM at min) as my unity/nominal gain??????? and again where should i set it??
or should i always look for TRIM AT MIN value of the line level inputs only, and ignore xlr TRIM AT MIN value??

Why use XLR from the preamp? Is the preamp's line out XLR? And if you did, notice the maximum acceptable level in at the MIC input (the XLR - that is what it is for and is expecting to see the low voltage of a mic) is only -14dBu vs +4dBu.
You can do that, but then you also end up having to toss a bunch of level you just gained from the preamp- to keep from clipping at a mic input!

i also read about that: consumer line level is at -10dBV, and professional line level is at +4dBu. so mine is a typical pro line level of +4dBu and that is that damn UNITY GAIN??

Again 'unity can mean no gain added, or it can mean (Mackie started this IIRC) 'gain staging up (or down) to get a signal into a unit's nominal' target operating level, nothing more.

thank uuu!

Yet Another HR BBS' success story!

 

[Farview]

Unless you're using ribbon mics....you don't need to worry about hurting a mic with phantom power.
Ev en if you only use dynamic mics and the phantom is accidentally on....it won't be an issue.

AFA you interface...just by looking at the picture in your post above....it looks to me like the phantom power is either on or off for both inputs.

He is talking about running phantom to an external mic preamps output. Because he wants to use the external mic pre on one channel and a condenser mic on the other. He only has a global phantom switch.

 

[Farview]

Yes, use a 1/4 TRS from the tube preamp. This gets you into the line input and makes the phantom power a non-issue.

 

[richardosim78]

Don't worry about the word 'unity right now. Look at the input volume knobs - see where it says 'Line'? That's your 'trim at min' (although it could be better called 'gain' at min) for line level inputs.


Why use XLR from the preamp? Is the preamp's line out XLR? And if you did, notice the maximum acceptable level in at the MIC input (the XLR - that is what it is for and is expecting to see the low voltage of a mic) is only -14dBu vs +4dBu.
You can do that, but then you also end up having to toss a bunch of level you just gained from the preamp- to keep from clipping at a mic input!

Again 'unity can mean no gain added, or it can mean (Mackie started this IIRC) 'gain staging up (or down) to get a signal into a unit's nominal' target operating level, nothing more.


Yet Another HR BBS' success story!

my tube preamp has both xlr and jack ins/outs.

so i have to keep tascam's knob all down to the left (where "line" label is) to be in that +4dBu unity gain (TRIM AT MIN)?? that will pass my tube preamp's signal to a computer without any intervention??

so if i use xlr, then i have to turn my knobs all to the right (where "mic" label is) to get that -14dBu unity gain (TRIM AT MIN)?? or keep it all to the left as well??

and what is TRIM AT MAX for then??

thanks

and yes, farview, thats exactly what i'd like to do with multiple mics. yes, tascam has global phantom switch. thanks

 

[Farview]

my tube preamp has both xlr and jack ins/outs.

so i have to keep tascam's knob all down to the left (where "line" label is) to be in that +4dBu unity gain (TRIM AT MIN)?? that will pass my tube preamp's signal to a computer without any intervention??

Yes. Once you get the signal to line level with the tube preamp, you plug it into a line input, which is what the 1/4 TRS input on your interface with the gain set all the way to the left is.

so if i use xlr, then i have to turn my knobs all to the right (where "mic" label is) to get that -14dBu unity gain (TRIM AT MIN)?? or keep it all to the left as well??

With a mic, you plug the mic into it and turn the gain knob until you have a good recording level. Where the knob ends up will depend in the sensitivity of the mic and how loud the source is. There is no specific setting that will work for everything.

and what is TRIM AT MAX for then??

When you are using a low sensitivity mic to pick up a quiet source.

and yes, farview, thats exactly what i'd like to do with multiple mics. yes, tascam has global phantom switch. thanks

Plugging the tube pre into the 1/4 TRS jack is the way to go. Phantom is only on the XLR, so you won't be feeding phantom to the tube preamps output if you use the 1/4 TRS.

 

[richardosim78]

With a mic, you plug the mic into it and turn the gain knob until you have a good recording level. Where the knob ends up will depend in the sensitivity of the mic and how loud the source is. There is no specific setting that will work for everything.

oh yes.. its when u plug mics straight into tascam.. but what if i wanna use all xlr cables between tube preamp and tascam? how to set that -14dbu trim to min on my tascam?? is it all to the left again??

 

[mixsit]

my tube preamp has both xlr and jack ins/outs.

so i have to keep tascam's knob all down to the left (where "line" label is) to be in that +4dBu unity gain (TRIM AT MIN)?? that will pass my tube preamp's signal to a computer without any intervention??

so if i use xlr, then i have to turn my knobs all to the right (where "mic" label is) to get that -14dBu unity gain (TRIM AT MIN)?? or keep it all to the left as well??

and what is TRIM AT MAX for then??

thanks

Geez guy try it! One way -counter clockwise, is min gain to take the highest voltages in, clockwise is for the most gain quietest lowest voltage sources. The two jacks (XLR and TS) both likely go to the same amp circuits, one just has it padded down for its use for line level's higher range of voltages.

 

[richardosim78]

well i will get my gear in a week or so... so im asking those questions so i wouldnt fuck up that gear and my mics when it arrives.. i'll have to do lots of recordings straight away with that tube preamp-souncard chain..
i want to know where r all these unity gain/neutral positions on that tascam by default..
thanks

 

[mixsit]

Yeah I thought you already had it.. Anyway, I think you got sidetracked with the 'unity/'neutral stuff. In the end it is going through what ever amp circuit's in there. The goal is- use the appropriate input, and the gain knobs where they need to go to get you to your nominal record target levels.
It'll make sense then once you get to turn some knobs.

 

[richardosim78]

pls answer my question on post #15. thanks

 

[gecko zzed]

pls answer my question on post #15. thanks

oh yes.. its when u plug mics straight into tascam.. but what if i wanna use all xlr cables between tube preamp and tascam? how to set that -14dbu trim to min on my tascam?? is it all to the left again??

Why do you want to do this?

There is nothing to be gained by it.

Use XLR to XLR from mike to preamp. Use TRS to TRS from preamp to interface. That's the best way of managing a line-level signal, and of avoiding any potential issues with the interface's phantom power if you run a second mike straight into the interface.

Oh, and by the way, demanding answers is not likely to win you any friends.