increasing headroom on an LA2a

Okay..I'm with Kingston on this one..I can't seem to get the gain staging idea thru to him ...if his LA is healthy then that is the only issue... Specifically when recording to DAW where at 24 bit resolution I think a MAX of -10 db on the peaks is a must (I will not go into a debate on why not to record hot to DAW or the concepts of digital gain staging). If his LA is not broken then it should drive his protools and interface past the red  clipping and into the magenta "I can't believe you are doing this to me" clipping..The only scenario I can think is that using dynamic mics (or ribbons) with the V72 he would struggle to push the LA2a hard enough to work properly...or the gain on the AMEK channels is not set high enough. One other thing struck me...if you wired the input transformer backwards by accident at 10:1 it would kill the gain of the unit?...

Cheers,
Ray

drpat said:

I'm still not 100% clear what the actual issue is. Does the unit distort when compressing? Does it distort when not compressing? Does it only distort with the V72 in front of it? Does it not compress enough? Do you feel that you're constantly setting the "GAIN" or "PEAK REDUCTION" controls to their extreme settings to make things work correctly? Does it make a growling noise every time you spit on your dog. Be specific, and you'll avoid all of the willy-nilly advice that people are giving you because they are guessing about what problem you're really having with the unit.

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Ah the fine art of gain staging....

Some folks never get it right.

If you're running something hot into the V72, you may be getting to much level into the LA2.

Try plugging a set of headphones into the outputs at each stage and having a listen.

Mark

I repeat,


    if he has his vocal fader at -7dB, I think he is clipping the amek. No amount of fudging will surmount this. I KNOW that there is little headroom with an Einstein . . .  .

reanimatorstudio said:

If you're running something hot into the V72, you may be getting to much level into the LA2.

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Yes, but that's not the case if I turn the makeup down, distortion dissapears.

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you are just asking for too much output from your LA2a!
padding the input won't help.
padding the output won't help.
it is just limited to +16 dBu.

on a side note: the German broadcast norm is still 0dBfs = +15dBu 
the reason Digidesign is making special output cards for us  :

reanimatorstudio said:

Don't think so. +20 dB is loud, I agree but not for a compressor. If you would like to have 0dB average output (which is not very loud) and you are compressing like 30 dB on peaks (what you can't see with a compressor VU meter), it is imaginable you will have transients of 18 dB and more.

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Argh.

again:

What dB?

26dBu output is stupid loud for a compressor. There aren't much gear in the world that will take such level.

Are you also somehow mixing make up gain (dB, relative to your input) to output level dBu (standard referenced to RMS AC voltage)?

Stop looking at the mixer leds and your protools dBFS. They don't mean anything to us without a quantifiable reference. Pick up your multimeter and start measuring and making notes.

reanimatorstudio said:

You say you hear "tube saturation". You don't, it's the transformer clipping.

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Could be, the only way to find out would be if I take my scope and measure before and after the output transformer, no?

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It'll only be tube saturation if your LA2A is broken. The feedback of the make up gain stages ensures that THD stays well below 1%. LA2A is a very low distortion unit. It would have been a grievous error by the original designers to make it anything else.

On the other hand the output transformer is very easy to clip, and it sounds bad in most cases. You wouldn't be the first to think it's tube saturation.

If you connect directly to the converter, and monitor back through the desk at unity gain, you would have the same problem . . . . . even if only back from the converters.

Why, in any case, do you want so much level into your converter? That's not the way to do it.

Those transients won't sound good up against 0dBFS at the converter any more than they will at +26dBu in the LA-2A.

As Raysolinski has already pointed out, you should be peaking your converters at -10dBFS, not zero!

Keep your levels moderate, make up gain after conversion - if necessary - and all is good.

Since you know there is limited headroom in your console, your operating level should be suitably lowered as a matter of course, anyway.

reanimatorstudio said:

That's another topic Magnetosound.

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No, it isn't. In your first post you stated that you wanted less input sensitivity and more output level from your LA-2A.

That says to me that your system operating level is way too high.

Later on you say that you want about 7dB more level at the output to bring your fader to zero, which suggests that your operating level is off by at least this amount, probably more.

Anyway,I started recording my mixes hotter now than I used to, and I don't see why I should go back.

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Your LA-2A doesn't go that hot, that's the reason.

I compared my mixes now and before, I compared (A/B)  my mixes on the console with the one I just recorded, nothing wrong.

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Sheesh, do you have a problem or not?

A lot of folks here are trying to help you, but you don't seem to like the direction in which they are all pointing you - lower levels.

reanimatorstudio said:

I bring all my faders 10 dB down in Protools?

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No, you work as usual in ProTools, but your operating level is lower because it comes in (and therefore out) lower. You don't need (or want) to slam anything in ProTools.

The issue is not your working practice, but your system level and how it is calibrated.


This should help. Adjust to taste, but within reason. 



Merry Christmas,

Dan

It's simple...

Calibrate your system so that 0dbVU on your console is -16dbfs on your DAW and vica-versa.

From the clues that I've picked up from this thread, I'm convinced that your home made LA2A was not built properly. Any healthy LA2A functions great with modern gear. I've got a few of the very early grey units (they only built about 400 of them), and have never complained about their performance in a modern environment. They've never distorted in any objectionable way whatsoever, and are usually quite forgiving of bone-head gain staging. My advice to you would be to find a reputable tech who is familiar with LA2A's specifically, and let them troubleshoot and fix whatever is ale-ing your unit.

I was asking you to compare your home made LA2A to the "Urei LA2A" that you have advertised on your studio website. Did you sell the Urei or something????

Before you take another paying client PLEASE do some study on the concepts of digital audio. Do some searches here if nothing else. I don't have time to explain it. Bit depth, jitter, inter sample distortion, error correction, noise floor, digital gain staging, dbfs...It doesn't make any difference if you are playing around recording yourself and your friends but the minute you hang out a shingle and start charging folks that is a different ball game.

Cheers,
Ray

reanimatorstudio said:

drpat said:

My advice to you would be to find a reputable tech who is familiar with LA2A's specifically...

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For analog that would be me or my father.

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Sounds like you don't really need any help then... Best of luck!

Give a man a fish and you will feed him for a day...try to teach him to fish and he will tell you your reel is wrong, your bait won't work, your line isn't strong enough and there are no fish in the river  :

Cheers,
Ray