Problems hooking up an M-30 Mixer

[sweetbeats]

Let's go back to nuts...

I'm more comfy there anyway...I learn more too.

BTW, sorry for the hijack.

So notice that all the pre's I mentioned are transformerless. I don't like how opamps distort when they get pushed and so on certain source material I have to make sure I leave enough headroom while doing what I can to stay above the noise-floor. When I set my mic trims at that point, that has been fine for digital. My peaks are typically around -2 ~ -3dB, average levels maybe -6 ~ -8dB, and I generally have gone straight to the AD converter right off the head amp (yes sometimes there's an eq or a dynamics processor in the chain, but I try to keep 0 as 0 and avoid trying to use the processor as a line amp because that's not really what its for). When I started using analog atr's again I found that what I had been doing with digital didn't work well...sending -3 peak levels left the noise floor too audible for my taste and I wasn't taking advantage of the capability of the +6 tape I use. So that's when I decided it was time to acquire an analog console so I had control over a secondary gain stage whether it be an input fader or a PGM buss fader. I always thought that my personal discovery was one of the prime reasons why it is important and valuable to have a traditional mixer in front of the atr...to avoid pushing amp stages and maximize the distance from the noise-floor at the same time. So...AM I nuts? If so, I want to understand what I'm doing wrong.

 

[RRuskin]

double post ignore

 

[RRuskin]

I'm more comfy there anyway...I learn more too.

BTW, sorry for the hijack.

So notice that all the pre's I mentioned are transformerless. I don't like how opamps distort when they get pushed and so on certain source material I have to make sure I leave enough headroom while doing what I can to stay above the noise-floor. When I set my mic trims at that point, that has been fine for digital. My peaks are typically around -2 ~ -3dB, average levels maybe -6 ~ -8dB, and I generally have gone straight to the AD converter right off the head amp (yes sometimes there's an eq or a dynamics processor in the chain, but I try to keep 0 as 0 and avoid trying to use the processor as a line amp because that's not really what its for). When I started using analog atr's again I found that what I had been doing with digital didn't work well...sending -3 peak levels left the noise floor too audible for my taste and I wasn't taking advantage of the capability of the +6 tape I use. So that's when I decided it was time to acquire an analog console so I had control over a secondary gain stage whether it be an input fader or a PGM buss fader. I always thought that my personal discovery was one of the prime reasons why it is important and valuable to have a traditional mixer in front of the atr...to avoid pushing amp stages and maximize the distance from the noise-floor at the same time. So...AM I nuts? If so, I want to understand what I'm doing wrong.

Not having a transformer at the input won't necessarily cause a preamp to behave as you describe. Describe your sources and the rest of the chain. Direct from electronic instruments, mics? Which ones? Are you using any noise reduction? If so, what kind? Btw - there is nothing inherently wrong with using the makeup gain from a signal processor or from using as many of the gain stages you have on tap on your console. I was just curious why you weren't getting enough signal straight off the mic preamps at your disposal.

 

[sweetbeats]

Mostly I'm sourcing mics...SM57's, an SM 94, Studio Projects C1 and B3's, Audix D-6, AKG D112...electric guitar and bass through DI's...the AKG mic is probably the noisiest. I've recorded both with and without n/r and it is really noisy without n/r unless I can push the levels.

My comment about the opamp distortion is related mainly to sustained vocal...that graininess...some is from the mic but I've found that some of it can be avoided by not pushing the preamp too hard.

So you're saying that even if my mic pre runs out of headroom at 0dB (as seen on the recorder VU, like totally out...peak indicator comes on at -3...), that should be good enough even though I prefer the sound with transient peaks at around +9 and average program at 0 ~ +3?

And on the topic of line amps and processors, I agree its acceptable to use the amps in processors, but I prefer to use it as makeup gain, not for boosting. Yes its fine, but I've got other line amps for doing that are more suitable for it and given the choice...

 

[RRuskin]

Mostly I'm sourcing mics...SM57's, an SM 94, Studio Projects C1 and B3's, Audix D-6, AKG D112...electric guitar and bass through DI's...the AKG mic is probably the noisiest. I've recorded both with and without n/r and it is really noisy without n/r unless I can push the levels.

My comment about the opamp distortion is related mainly to sustained vocal...that graininess...some is from the mic but I've found that some of it can be avoided by not pushing the preamp too hard.

So you're saying that even if my mic pre runs out of headroom at 0dB (as seen on the recorder VU, like totally out...peak indicator comes on at -3...), that should be good enough even though I prefer the sound with transient peaks at around +9 and average program at 0 ~ +3?

And on the topic of line amps and processors, I agree its acceptable to use the amps in processors, but I prefer to use it as makeup gain, not for boosting. Yes its fine, but I've got other line amps for doing that are more suitable for it and given the choice...

On the rare occasion when I need to push a preamp into it's "asking too much gain from it for it too sound good" zone, I'll give it more level to work with. Change to a hotter mic, turn the instrument and/or amp up.

Some things to keep in mind:

1. Depending on the source, peak lights will come on with an average level of as little as -10 on a VU meter. A garden variety dynamic inside a kick drum comes first to mind.) Depending on the piece of gear, the peak light could actually represent anywhere from +3 to +15 or so.

2. As I've stated (preached?) before, when using NR, especially dbx, printing as hot as you are is counter productive. The NR doesn't behave properly and as you have already noticed, the shortcomings of the rest of the chain begin to crawl out of the woodwork. The whole idea of NR is to keep the tape quiet enough so that you don't have to run everything super hot just to overcome tape noise.
3. Yet another thing many don't realize is that that wonderful sonic splat that is so cherished with saturation is subject to self erasure/smear the more times the tape gets passed over the heads. Saner levels lessen this.

 

[sweetbeats]

Okay.

The pre's I've most commonly used have peak LED's set to light at -3, and I find that they do clip at 0.

My deck's peak LED's light at +10 so of course I'm not seeing any action there. I'm talking specifically about the peak LED for the pre.

I've heard (read) your advice about levels when printing using n/r and I've heeded them. The levels I cited in my last post (i.e. +9 transient peaks with program averages of 0 ~ +3) are without n/r.

Change to a hotter mic

Its not an issue of the mic not being hot enough...typically the trim knob on the pre is somewhere between 12 and 3 o'clock, but its the level of the preamplified signal at the direct line-level out of the preamp that calls for a secondary gain stage, not that I've run out of gain at the head amp.

So what's the industry's point of putting secondary gain stages on mixers if all we need are head amps? I don't get it.

Regarding #3, I don't do sonic splat.

 

[A Reel Person]

My friend,...

thats interesting reel. i noticed on the M308 i always needed to pull out the 'line in' plug in order to listen back to the track. is this different on the M30? It was most likely something i was doing wrong

You'll have to excuse me for having forgotten what I consider a caveat of the M300 Series design. The Tape Rtns all get routed thru their respective 1/4" Line-In jacks, whereby plugging something into the Line-In jack will create a breakpoint in the Tape-Rtn signal. A caveat,... to be sure. I'm not sure what's the purpose of this design, but there it is. My apologies.

What I've focused on was that there's no such caveat on the M30, as the Tape-Rtn and Line-In jacks are both RCA-type, and are completely separate signal paths in the circuitry. My mistaken picture of what you were doing was that you had the Tape-Outputs from the R/R plugged into the Line-In jacks on the M30, while trying to share it with an external preamp by plugging and replugging them alternately.

Sorry for the confusion that I might have injected into the analysis. I have decades of use with the M30 and know it by memory, but little or no use with the M300's past a basic soundcheck, and as such I had to consult the manual. My M312 isn't hooked up for easy access at this time.

My mistake on the M300's, but it's something to keep in mind and watch out for! The caveat of this particular section of the design I've not fully grasped the utility of,... other than maybe Tascam wanted to go on-the-cheap with shared circuitry instead of separate circuitry for Tape-Rtn and Line-In.

No such caveat on the M30,... but I'm getting redundant.

Cheers

 

[sweetbeats]

Dave...go to bed, man!

 

[RRuskin]

Okay.

The pre's I've most commonly used have peak LED's set to light at -3, and I find that they do clip at 0.

My deck's peak LED's light at +10 so of course I'm not seeing any action there. I'm talking specifically about the peak LED for the pre.

I've heard (read) your advice about levels when printing using n/r and I've heeded them. The levels I cited in my last post (i.e. +9 transient peaks with program averages of 0 ~ +3) are without n/r.



Its not an issue of the mic not being hot enough...typically the trim knob on the pre is somewhere between 12 and 3 o'clock, but its the level of the preamplified signal at the direct line-level out of the preamp that calls for a secondary gain stage, not that I've run out of gain at the head amp.

So what's the industry's point of putting secondary gain stages on mixers if all we need are head amps? I don't get it.

Regarding #3, I don't do sonic splat.

You are running up against the limitations of preamps built to a price rather than for performance. They're what some old-timers would call "tender." This doesn't mean you can't do good work with them, just that one needs to be mindful of how hard they can be pushed.

For the sake of argument, Assume that when the dbx nr is switched out and 0 from your preamp = 0 @ throughout the tape deck and back to the board's tape returns:
When the dbx is then switched in, your -3 is actually being recorded twice as hot as that to the tape. Conceivably, you can hit the tape even lighter and still have a quiet recording. BTW - once the dbx is switched in, you can't trust your machine's meters anymore because they aren't reading what the preamp (or anything else) is feeding them. They are reading the compressed/encoded dbx'd signals. You might consider getting something like an MB-20 to place ahead of the dbx just to visually monitor what's really happening.

With regards to +9 peaks: I'm not convinced that TASCAM machines have that much headroom in their electronics. Unless I misunderstood, you are already pushing the input section to reference the tape to +6. Asking +9 more on top of that isn't something I would do. (YMMV)

As far as secondary gain stages go, when you need 'em, you need, 'em: eq sections, buffers, summers.

I want to emphasize that you aren't doing anything wrong. The statement that your preamps weren't providing enough gain to tape piqued my curiosity.
All that matters is if you are content with your recordings.

 

[sweetbeats]

Rick, great post.

The dbx level stuff is always good to read...I think I reference info from a post you put up some time ago when I was asking about levels when printing with dbx.

Experiment, experiment, experiment. right?

And the +9 thing...that is +9 on the deck when monitoring the input. So if my peak LED's are set to light at +10, I'm setting my input level peaks just below peak LED's lighting, not the sum of +9 and +6. And a lot of what I'm tracking is percussion, so those transients are well above averages.

That's really interesting about the preamps. Most of my work has been with the pre's in the i88x and the Digimax...the former has gotten particularly good reviews in terms of transparancy and self noise...haven't done as much with the older Tascam pre's I have. Maybe they will have a little more oomph to them, maybe not. Bottom line is that I know I have more here than I need to get the job done.

And the meter thing...that's one of the nice features of the M-520...it basically has two MB-20's built in as the meters for PGM groups 1 ~ 8 have an external loop with a foldback so you can basically meter anything you want at any point in the chain, patch it in and switch it in or out in groups of 4. Good idea, but the same as monitoring the input at the atr right (assuming the meters are calibrated properly yah)?

 

[RRuskin]

Rick, great post.

The dbx level stuff is always good to read...I think I reference info from a post you put up some time ago when I was asking about levels when printing with dbx.

Experiment, experiment, experiment. right?

And the +9 thing...that is +9 on the deck when monitoring the input. So if my peak LED's are set to light at +10, I'm setting my input level peaks just below peak LED's lighting, not the sum of +9 and +6. And a lot of what I'm tracking is percussion, so those transients are well above averages.

That's really interesting about the preamps. Most of my work has been with the pre's in the i88x and the Digimax...the former has gotten particularly good reviews in terms of transparancy and self noise...haven't done as much with the older Tascam pre's I have. Maybe they will have a little more oomph to them, maybe not. Bottom line is that I know I have more here than I need to get the job done.

And the meter thing...that's one of the nice features of the M-520...it basically has two MB-20's built in as the meters for PGM groups 1 ~ 8 have an external loop with a foldback so you can basically meter anything you want at any point in the chain, patch it in and switch it in or out in groups of 4. Good idea, but the same as monitoring the input at the atr right (assuming the meters are calibrated properly yah)?

The ATR's input monitor is still looking at the dbx'ds signal and not telling you what is actually coming off the board.

Recording percussion with peaks of +9 with dbx engaged is overkill. Dbx isn't happy with anything much over +2. Try recording a kick or snare with an average of -10 to -5 and see how clean and with how much "pop" it sounds on playback.

 

[sweetbeats]

Rick, I must not be making myself clear...it makes sense to me when I read back on the past few posts, but that's just me. I don't track with +9 peaks when using dbx...and I know the meters on the atr are going to display encoded signal. I'm using the decks meters to monitor input levels when not using n/r and, depending on the source material and the desired result, may psuh transient peaks to as much as +9 or so without dbx engaged...when using dbx I typically shoot for keeping levels at no more than 0VU.

 

[RRuskin]

Rick, I must not be making myself clear...it makes sense to me when I read back on the past few posts, but that's just me. I don't track with +9 peaks when using dbx...and I know the meters on the atr are going to display encoded signal. I'm using the decks meters to monitor input levels when not using n/r and, depending on the source material and the desired result, may psuh transient peaks to as much as +9 or so without dbx engaged...when using dbx I typically shoot for keeping levels at no more than 0VU.

Now it's clear. With or without nr, I still don't think you need to hit the tape that hard. Different strokes & all that.