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joe17

sound devices 633 inputs 4-6

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joe17   

Hey there,

Just wanted to confirm if this is normal and happening to everyone else - ive been using two ucr411 and one lr into inputs 4-6 of my 633 and they are all set at +5 coming in - getting normal level on the transmitters - not hitting red - but when i turn the gain up on the inputs 4-6 to get a good signal (will be pretty high almost highest at +16 or less if possible usually at around +12 - +14 though) on the peaks i get this unusuable clipping sound like someones blowing into the mic? 

Is this normal for a line input ? should i be playing it less hot ? but then less signal/noise ? 

have attached recording sample for input 4 - but its the same across the 5 and 6..

 

Cheers, 

Joe

input4clip.wav

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Your trim settings on 4-6 with line level Lectrosonics should be around 10 to get you fader at 12 o'clock with good SN.

PFL input, use select knob to adjust trim.

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A few thoughts..  who knows..

Are your ISO tracks clipping??

Go to your channel 4 PFL switch, get that first menu up, then adjust the trim using the SELECT knob to a proper level .... then play with the fader...   The channel 4-5-6 trims are found in that PFL menu...

Do the same for Ch. 5 and 6....    On Ch. 1-2-3 the trims are there with knobs.... 4-5-6 are not.

If you know all this and you are still getting this distortion, checked the mic??  

Are the limiter settings on and correct?  With the settings at normal, I can shout into the mic and the limiter saves things...  They won't sound like that...  

Sounds like the trim is not set and is distorting that channel from the get go..  Like the limiter is not engaged... and it's being over driven...

 

I stick to +8...with a bunch of +12.....  that's about it...  Once in a while,warmer..

 

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joe17   

thanks for the replys! 

the mics are all fine and the transmitters/receivers are good - cannot recreate the problem with mic inputs 1-3 with the same gear..

the limiter settings seems to have no effect when changed the same noise occurs - at the moment its on across all isos on hard knee at 18dbu 

but have played around with dropping the limiters down, using soft knee etc same noise..

its happening at the isos - that file i uploaded is the input 4 iso raw 

if anyone else drives their 4-6 gains up do you get the same noise?

even when the trim is at +8 or +6 wherever it is, whenever these inputs peak/clip/get close to clipping this noise occurs

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I had the same issue and it took some time before I realized (thanks to a post from another user) that the input limiters for channels 4-6 on the 633 are post A/D converter. There are no "analog" limiters on those inputs. Because of this... it seems you can overload the A/D converters when you push the gain causing a nasty digital clipping. The meters on your iso's or mix will not necessarily be anywhere near the red when you encounter this clipping. I've started limiting the use of the gain on the 633 (ch4-6) to no more than 4-6 dB and being sure to boost the gain on the tx when I need more. The tx is the best place to get the proper gain anyways but it's not always easy to make adjustments to our tx when your not a Zaxcom guy/gal(no Zaxnet)... so this is a little unfortunate. I now ride the tx gain a little higher than in the past so that I'm sure I don't have to gain up the pots on 4-6 too high and it has solved the issue for me. I hit the tx limiters a little harder from time to time but that's music to my ears when compared to the nasty digital clip I was getting before.

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In the design of the 6 series recorders, I think the assumption was that the line level inputs would be fed from radio mics, and that users would set gain so that the limiters on the radio mics engaged before allowing a signal strong enough to overload the analog inputs on the recorder. The problem is that most people don't like the limiters on radio mics (Lectro for me), so typically set levels so that they do not engage and utilise the mixer's limiters for strong signals.

If you are using the line inputs on 6-series machines, you must set your transmitters higher so their limiters engage.

It really is the flaw, as I see it, with the 688/CL12 combo. Inputs 7-12 have no limiters.

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I have noticed this on both my 633 and 688. 

Kind of makes those inputs unusable. 

I would have preferred to pay a bit more to buy and a more professional unit. 

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Dutch   
12 hours ago, chris_bollard said:

I have noticed this on both my 633 and 688. 

Kind of makes those inputs unusable. 

I would have preferred to pay a bit more to buy and a more professional unit. 

Not sure what you mean by more professional unit as they all have their drawbacks Chris. I just run the inputs through my 302 and into 5 and 6 when using my 633 when additional analog are needed. I'd put my recording results using SD equipment against anything on the market in a field comparison. Not knocking other equipment either as it's all give and take.

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Derek H   

Are you guys mistaking VU metering for peak metering? The 6-series can display either or both. 

 

Personally, I use peak only. I trim the isos so they peak around -20dbfs or a bit above and have no issues. Using the same gear as you. 

 

Just turn down the trim!

 

 

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Yep, Im on peak metering. Been that way since before I got my first 442. 

And yes the "solution" is to under record the ISO tracks. 

Back to my initial post, I would have preferred to pay more for each unit and have hardware limiters on 4-6/7-12, so that all tracks are equal. I can understand that maybe other users don't see this being that important. 

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9 hours ago, chris_bollard said:

And yes the "solution" is to under record the ISO tracks. 

Shouldn't be a problem as long as the signal/noise is good.

The machine isn't supposed to do all the work for us.  Thats for the AI swiss made robot in the future who takes all our jobs or we keep in storage and rent to productions.

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I don't see the issue.  If your isos are too hot back them off.  If they get recorded a bit low they will be boosted in post.  Better low than clipped.  What makes a machine "professional"?  A "professional" using it.

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Dutch   

Of course you always leave headroom, that's elementary! I love the size of my 633 but realize that there's always a trade-off between size and function. Surely it would be the size of a 688 if it had six analog in's. Chris's comment about it not being a professional unit because of this trade-off was quite untrue as exampled by the many great sound recordists using this gear.

When working on unscripted projects you quickly learn the benefit of hardware limiters which has nothing to do with proper gain and headroom settings.

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45 minutes ago, Dutch said:

Of course you always leave headroom, that's elementary! I love the size of my 633 but realize that there's always a trade-off between size and function. Surely it would be the size of a 688 if it had six analog in's. Chris's comment about it not being a professional unit because of this trade-off was quite untrue as exampled by the many great sound recordists using this gear.

When working on unscripted projects you quickly learn the benefit of hardware limiters which has nothing to do with proper gain and headroom settings.

I actually think they could do mic inputs on 4-6 if they wanted to--they fit 8 pres in the 788, right?  They didn't, I guess they have their reasons.  If your radios are hammering your inputs 4-6 consistently and backing off doesn't help then maybe the Zax wireless system would suit you.

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Dutch   

I have a lot invested in Lectro's but really like the new Zax wireless after working with a peer who swears by them. Just been waiting on the FCC auction which just ended and saving a few more $$$ before taking the plunge.

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1 hour ago, Dutch said:

I have a lot invested in Lectro's but really like the new Zax wireless after working with a peer who swears by them. Just been waiting on the FCC auction which just ended and saving a few more $$$ before taking the plunge.

If your going to take the plunge you will be safe with the .5 lower band. 

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Dutch   

Thanks Glen, as I typically work in small market areas it's important to invest in gear carefully. Looking forward to the early summer specials and word back about the latest and greatest from the NAB show.

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Yes Phil,  mic pres would be nice and solve the problem. The size is convenient so I guess that is what drove not having them. Limiting at the transmitter isn't suitable as I don't like the sound of that. It was an issue on one series ; the post dept specifically asked for the ISO levels to be higher. And then you risked clipping. 

Also, not super happy about ISO levels not being consist across all the tracks. 

Sorry if I offended any one with my "more professional"  comment.  Of course SD make professional gear, just don't really understand the thinking behind what was done at the design stage. 

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Maybe hitting a price point, maybe not cutting into 688 sales, maybe design limitations of the 6xx deal (that weren't there in 7xx), who knows.  The 633-88 seem like they were a clean sheet of paper vs. the analog mixers, the 664 and the 7xx, and I know they did a lot of talking to soundos about what they wanted and were willing to pay for.   The community has kind of voted with its feet and wallet, no?   That doesn't mean it's the best, it means it balances $ vs features in a way people like, I think.  I think there is going to be a new run of machines soon that are cheaper, cheesier and probably much higher tech than what we have now, of which the F8 is only the first.  These new decks will do all kinds of stuff but will make older recorders like 7xx seem like analog Nagras in terms of solidity and apparent ruggedness.  Ruggedness is expensive.

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+1
At the risk of being controversial I think the 788 sounds better than the 6xx. But the 6xx is lighter and more power efficient. 

I don't think that's very controversial. Personally, I fully agree

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daniel   
3 hours ago, Constantin said:


I don't think that's very controversial. Personally, I fully agree

Sounds better when you're using it or after it's been through post?

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