Pre Amp Behavior? Is this correct?

I edited my post, but yeah, you'd kind of have to. In fact, you'd mostly just be using the Master to undo the preamp gain. It actually looks to me like this box is basically intended for pounding the preamp into saturation and the cranking it back down to reasonable levels.

Sure, but you'd start it at the 0 mark, set the gain normally, then start raising the gain for saturation and lowering the master to keep the record level correct. Starting with the master nearly all the way down is nuts.
 
I mean, I personally wouldn't bother with a channel strip like that, but...

The minimum gain on that knob is +20db which slams a +4dbu signal right into the rails to begin with. Turning it up more can't really affect the level. It won't get louder, just more distorted. You could engage the pad, or like use the line input which is actually meant for line level signals.
 
I might have missed the point entirely but as others have stated, putting a +4dB signal to a mic input is not correct.

A professional mic input level is about -60dB and he is putting in +4dB which means that he is putting in about 64dB to much signal, almost like connecting a torch globe to a domestic (for the USA) 110volt supply ---- the globe aint gonna like it !!!!!

Of course he will have to turn the volume control knob (or whatever) virtually to zero and any movement off the zero mark will naturally cause the unit to peak. I am actually surprised that he hasn't fried the input stage.

Don't they say -- "a little knowledge is a bad thing" !!!!!

Or have I read him completely wrong !!!!!!!!!

David
 
I might have missed the point entirely but as others have stated, putting a +4dB signal to a mic input is not correct.

A professional mic input level is about -60dB and he is putting in +4dB which means that he is putting in about 64dB to much signal, almost like connecting a torch globe to a domestic (for the USA) 110volt supply ---- the globe aint gonna like it !!!!!

Of course he will have to turn the volume control knob (or whatever) virtually to zero and any movement off the zero mark will naturally cause the unit to peak. I am actually surprised that he hasn't fried the input stage.

Don't they say -- "a little knowledge is a bad thing" !!!!!

Or have I read him completely wrong !!!!!!!!!

David

No, person with a fine name, pretty sure you are right. I would however like to comment about a possible "fried input stage"?

Quite often, dire warnings are given in forums about connecting various devices and "levels". The standard design rule is that anything should be made to cope with a signal equal to the internal supply rails. For budget kit that is likely 24 volts*. That is the peak to peak signal. The "normal" way to express signal voltages is "rms" and so 24V p-p = 8.5V rms or +18dBV, almost +23dBu.

Now of course, very cheap gear might leave out the protection diodes needed even though the cost is trivial, but that is a chance you take going for really budget kit. Not likely though these days IMO because mic pres HAVE to stand the pulse of 48V. Won't be quite 48V but a totally unprotected input would pop in short order I would say.

So, ye budget buyers! Unless you go down to the REAL whale ***t dept, you should be able to plug any piece of gear into any other, except speaker levels from power amps.

*"Pro" gear will have 30 or 36 V rails and one can assume very good protection and RFI stoppage.

Dave.
 
It's already clear from previous reactions, but putting a 'line-level' signal into the mix preamp is definitely NOT the way to do this.

But I'd try with setting the master volume to 0dB, connecting the microphone and testing with the source you'd like to record.
Use the VU-meter to get an idea, with the VU switch to MTR-OUT and compressor switch on 'OUT'(disabled). Also set other dials like EQ gain knobs to 0dB (12 o'clock).
Check the levels on the DAW to see if the resulting level is decent (don't try to hit max, avoid max on your DAW meter at all costs. Averaging about half the input meter should be fine (when recording in 24-bit at least..)). You can use the master dial to adjust if the difference between the VU-display and the DAW-meter is too big.

Adjust the gain knob to get a good level from the microphone. The gain can't be 'calibrated' for all purposes, it's different for different sound sources, microphones and setups, so you should find a good setting for each new recording.

Good luck!
 
So,

I got it all sorted out. +4 was definitely NOT the way to calibrate

I have the mic pres/Channel strips humming along nicely now.

Source material consists of, Acoustic Guitar, Elec Gtr, Bass DI, mic'd up drum kit, Keyboards, and Vocals.

Im getting some good recordings that im happy with.

Here is the rack im using for this project. thanks for all the help
20190121_235157.jpg
 
ashcat_lt

curious, why wouldn't you use a channel strip like that?

Also , forgive me ignorance on the whole calibration subject. Im actually an AVID Pro Audio ACSR. Been doing this crap along time, but have never had to calibrate with test tones before like i was asked to for this project. As an ACSR we mainly deal with Pro Tools related issues, concerning S6 Consoles, network connectivity, and mainly making Avid Products work well with one another. calibration is usually done, if at all by one of the engineers on staff. but in any case, i was asked calibrate, so i gave it the old college try. with of of your help of course, so i thank you.

HCR
 
Perhaps "calibrate" is the wrong word here? There is some merit in veryfing a specification.

A good part of my job with the guitar amp peeps was to "spec check". The designer produces a set of instruction. Mains volts, signal input levels and frequencies and control settings. Then the outputs at speaker jack were checked.

I could post a sample if anyone was interested? The exact model would be redacted.

Dave.
 
Perhaps "calibrate" is the wrong word here? There is some merit in verifying a specification.

A good part of my job with the guitar amp peeps was to "spec check". The designer produces a set of instruction. Mains volts, signal input levels and frequencies and control settings. Then the outputs at speaker jack were checked.

I could post a sample if anyone was interested? The exact model would be redacted.

Dave.

I think you maybe correct here. Calibration, Volts, nominal operating levels, not really my area of expertise, getting avid hardware and and software to talk to each other from 5 floors away is really what i do, i do home recording as well, just my own stuff. I use an omni interface, no pre amps, or outboard. and a mac book....and thats good for my personal stuff. i have been doing a whole lot of Dante networking in post facilities as of late. so i might have bit off more than i should have with the whole "calibration thing" but in the end it worked out. nothing blew up, no input stages got fried, and the project is going forward quite nicely.
 
ashcat_lt

curious, why wouldn't you use a channel strip like that?
I mean, why would I? I've got all that stuff in the box with a lot more options and flexibility and power. There's no good reason to print those things during tracking. It sounds like you might be in a situation of trying to use it to "idiot proof" a system for somebody else's use, and I guess that might be a bit different, but nothing I do needs anything like this.
 
I mean, why would I? I've got all that stuff in the box with a lot more options and flexibility and power. There's no good reason to print those things during tracking. It sounds like you might be in a situation of trying to use it to "idiot proof" a system for somebody else's use, and I guess that might be a bit different, but nothing I do needs anything like this.

Actually yes,

its all set up and working, my job is done. But....I gotta say, we did some test recordings, and that Joe Meek channel strip?, im kinda digging it...got a cool sound to it....
 
Back
Top