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Fusion analog inputs unusual behavior


gabi
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I just got my Fusion and I hope I am doing something wrong here. Unfortunately, I have a colleague that has experienced the same problem with his Fusion.

I've tried to align my Fusion to my Lectro receivers and to my suprise each input behaves in a different way. Pics attached. Lectro receivers set to  4dBu, all Fusion input trims set to 0 and each input read a different level. I used my Sound Devices 442 to double check and got the same unusual behavior, almost 10 dBs of difference from channel 4 to 5. Line up tones from all Lectros to my AD 147 read just fine, all trim pots in the same position give me the same level. I did not contact the manufacturer yet but I intend to (before the Senator asks).

Serial number # 20163

Anyone else?

Gabi Cunha

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Gabi, thank you for the excellent documentation/pictures that show the problem. Something is not right but I'm sure that Zaxcom will help out on sorting this out. I wonder if it has anything to do with the direct outs on your Audio Developments mixer? Are the direct outs balanced or unbalanced (looks like 1/4" connectors butI don't know if they are balanced TRS or not). I really can't think of another theory to explain that big a difference input to input. I do know that there can typically be a 1 or 2 db difference (Glenn explained this to me a long time ago when I discovered differences setting up the trim levels) but I don't think any of us have seen a 10db difference.

-  Jeff Wexler

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Gabi, thank you for the excellent documentation/pictures that show the problem. Something is not right but I'm sure that Zaxcom will help out on sorting this out. I wonder if it has anything to do with the direct outs on your Audio Developments mixer? Are the direct outs balanced or unbalanced (looks like 1/4" connectors butI don't know if they are balanced TRS or not). I really can't think of another theory to explain that big a difference input to input. I do know that there can typically be a 1 or 2 db difference (Glenn explained this to me a long time ago when I discovered differences setting up the trim levels) but I don't think any of us have seen a 10db difference.

-  Jeff Wexler

Not that it helps in the explanation but balanced or unbalanced direct outs are not the problem. Either way they should be the same output level.

Eric

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I've seen this once or twice back when the Deva IV and V came out. I don't remember what the exact fix was at the time, because new software versions were coming out so quickly at that time, but I do remember Glenn and Howy being very helpful and quick to solve the issue.

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I do know that there can typically be a 1 or 2 db difference (Glenn explained this to me a long time ago when I discovered differences setting up the trim levels) but I don't think any of us have seen a 10db difference.

Yes, I've also consistently seen this phenomena on my Deva 5.8 / Mix 12, maybe a 1 or 2dB difference with line level signals. I just figured, eh, I'll trim the difference out. It is odd, but not a deal-breaker.

--Marc W.

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Excellent documentation, Gabi. I would attribute this to sloppy QC on Zaxcom's part. While not as severe as your's, I had a couple of inputs on my Fusion that were lower than the others. Next time the Fusion traveled to Pompton Plains, they were happy to even them up for me (free of charge, of course.) Their service and support is second to none, imo.

Paul

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Hi Gabi.

Call me tomorrow I can help you out.

Glenn

Glenn, 

 

The problem of my Fusion 10 is identical to this of the Gabi. 

 

With a Neutrik Minitaror MR1 in 0dB/1KHZ > line and -40 >  mic, directly and each input of Fusion (checking in line and also mic - same result), Fader and Trim of Fusion in the position 0. I suspect of the pots of Fader. 

 

Some idea?   

 

Thank you, 

Gabriel

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The inputs of the Deva and the Fusion are designed with photocell gain control. These circuits vary greatly. The reason we use them is that nothing we have tested sounds better. The input channels vary +/- 3 dB and this is normal. This is the reason we have a trim menu page. It is used to calibrate the inputs to a constant level. If the input trims are calibrated and the channels are selected pre fader everything will line up perfectly.

If a channel is off more than +/- 3 dB the unit can be sent to us for calibration to get it to be closer but as long as all channels can be calibrated to a 0dB level there in nothing to worry about.

Glenn

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The inputs of the Deva and the Fusion are designed with photocell gain control. These circuits vary greatly. The reason we use them is that nothing we have tested sounds better. The input channels vary +/- 3 dB and this is normal. This is the reason we have a trim menu page. It is used to calibrate the inputs to a constant level. If the input trims are calibrated and the channels are selected pre fader everything will line up perfectly.

If a channel is off more than +/- 3 dB the unit can be sent to us for calibration to get it to be closer but as long as all channels can be calibrated to a 0dB level there in nothing to worry about.

Glenn

Thank you for your answer, Glenn!     

     

For me, to send from  Brazil to Zaxcom, it is very risky and expensive.     

Can you send instructions for resolved here in Brazil by my trust technician? I can lose the warranty without problem.

Tks,

Gabriel

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Hey Glenn, If you're still following this thread, I'm having an issue with the output level of my fusions's outputs 5 and 6 being a different level (maybe 5-6 db difference).  I'm experiencing this through the DSub out and the 10-pin Hirose. Is there an output trim I'm missing? Is something going on with the fusion?

E.

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The inputs of the Deva and the Fusion are designed with photocell gain control. These circuits vary greatly. The reason we use them is that nothing we have tested sounds better. The input channels vary  /- 3 dB and this is normal. This is the reason we have a trim menu page. It is used to calibrate the inputs to a constant level. If the input trims are calibrated and the channels are selected pre fader everything will line up perfectly.

If a channel is off more than  /- 3 dB the unit can be sent to us for calibration to get it to be closer but as long as all channels can be calibrated to a 0dB level there in nothing to worry about.

Glenn

Hi Glenn,

I certainly did use the trim page to calibrate the inputs. I just thought 10 dBs of difference to be too much for a machine of this price range and reputation. I was expecting some precision and quality control (not that I question the quality of the preamps, but precision  and symmetry are qualities to be expected of professional gear). I love the recorder by the way, especially the touch screen, low power consuption and routing possibilities.

Thanks for the replies, guys.

Gabi

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Hey Glenn, If you're still following this thread, I'm having an issue with the output level of my fusions's outputs 5 and 6 being a different level (maybe 5-6 db difference).  I'm experiencing this through the DSub out and the 10-pin Hirose. Is there an output trim I'm missing? Is something going on with the fusion?

E.

Dont know if this applys in this case but unbalanced inputs/outputs are usually 6db lower than balanced ones.

Eric

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How does one record a correctly ballanced stereo or multi-channel b/g when all the analogue ins are calibrated all over the place?! A mic does not output calibration tones so hownam I going to set my levels when recording stereo b/g's? On every other machine I can set the gain to visually the same trim lebel and get a perfectly alligned recording. I'm a bit shocked that on a deva the analogue ins are randomly far apart and it's left to the user to find the correct allignment? In the dield this is more or less impossible to do, or do we need to pull out our caliration unit every every time we want to record a stereo or 5.0 b/g?

I'm confused.

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How does one record a correctly ballanced stereo or multi-channel b/g when all the analogue ins are calibrated all over the place?! A mic does not output calibration tones so hownam I going to set my levels when recording stereo b/g's? On every other machine I can set the gain to visually the same trim lebel and get a perfectly alligned recording. I'm a bit shocked that on a deva the analogue ins are randomly far apart and it's left to the user to find the correct allignment? In the dield this is more or less impossible to do, or do we need to pull out our caliration unit every every time we want to record a stereo or 5.0 b/g?

I'm confused.

I am disappointed with Zaxcom. Cannot the machine be calibrated before leaving the factory? Several units in the same conditions. That is headache to the user!

Gabriel

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The input trim must be set by the user in the field. It is impossible to not have an input trim function on any location recorder. This type of circuit provides very smooth transitions without digital steping common to other recorders. The trim function needs to change with different input levels so it can not be calibrated at the factory. The difference in levels between channels is normal in this case and does not present any issue when the input trim is set properly. Since this is an analog circuit with a adjustment range of about 30dB the +/-3 dB offset that we typically see is very normal.

Glenn

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It is possible the 10 pin output is loading down the DB25. Disconnect the 10 pin and see if the DB25 levels return to normal. Give me a call if you need more info.

Glenn

Hey Glenn, If you're still following this thread, I'm having an issue with the output level of my fusions's outputs 5 and 6 being a different level (maybe 5-6 db difference).  I'm experiencing this through the DSub out and the 10-pin Hirose. Is there an output trim I'm missing? Is something going on with the fusion?

E.

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The input trim must be set by the user in the field. It is impossible to not have an input trim function on any location recorder. This type of circuit provides very smooth transitions without digital steping common to other recorders. The trim function needs to change with different input levels so it can not be calibrated at the factory. The difference in levels between channels is normal in this case and does not present any issue when the input trim is set properly. Since this is an analog circuit with a adjustment range of about 30dB the +/-3 dB offset that we typically see is very normal.

Glenn

Glenn, 

 

 

I have 744T, 702T, 788T,  Tascam HD-P2,  Tascam HS-P82, Zoom H4N, Nagra LB and Nagra VI. 

In none of these machine  exists larger difference than 1dB among the inputs! 

Ok Fusion with difference of 3dB, but 10dB.... 

 

If you can send me the schematic, I make the necessary corrections here in Brazil, without problem. I know as correcting these differences. If you can send for me pots and fotocelulas  selected, my extra expense it will be smaller. 

 

Thank you, 

Gabriel 

 

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The input trim must be set by the user in the field. It is impossible to not have an input trim function on any location recorder. This type of circuit provides very smooth transitions without digital steping common to other recorders. The trim function needs to change with different input levels so it can not be calibrated at the factory. The difference in levels between channels is normal in this case and does not present any issue when the input trim is set properly. Since this is an analog circuit with a adjustment range of about 30dB the +/-3 dB offset that we typically see is very normal.

Glenn

I wasn´t talking about setting the trim being impossible in the field. I meant that setting all the trims to the same amplification (as per reading of the display) and have different levels across the board is something I haven´t seen so far. At least not that coarse. No one I know would set different trims for each channel when he plugs in a stereo-mic or a 5.1 rig. People assume that if the trim is set to 0dB it´s at 0dB for all those channels.

Or how would you recommend setting input trims for a stereo mic. Isn´t the first thing we all do is set both channels to identical setting assuming that the inputs behave the same way?

But maybe Gabi´s machine is having a problem...

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I wasn´t talking about setting the trim being impossible in the field. I meant that setting all the trims to the same amplification (as per reading of the display) and have different levels across the board is something I haven´t seen so far. At least not that coarse. No one I know would set different trims for each channel when he plugs in a stereo-mic or a 5.1 rig. People assume that if the trim is set to 0dB it´s at 0dB for all those channels.

Or how would you recommend setting input trims for a stereo mic. Isn´t the first thing we all do is set both channels to identical setting assuming that the inputs behave the same way?

But maybe Gabi´s machine is having a problem...

The problem of Gabi's F12 is the same of my F10. Sees the pictures: 

To solve this problem, I intend to change the pots and the photocell gain control

Gabriel

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Am I missing something?  Why don't you just plug in a tone generator and set each trim to 0 (or -10 or -20 or whatever)?  Once they are set forget about them.  They will all be equal.

Billy Sarokin

Billy,

Your Deva also has the same problem and you solved this way?

Gabriel

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All my inputs are set differently.  Some are line level, some mic level and there are variations between inputs.  I never checked how much (but I will check on set tomorrow).  My guess is a 6-8db variation (which is close to spec, since + or - 3db can be 6 db between two inputs.  I feed a -20 tone into each input and set the trim show -20.  As long as I can reach -20 without pushing the trim to max in either direction all is good.  Once my trims are set my mic pre amps are optimized.  I'm not even sure how I would compare each input because the trim pots do not pass audio, they are digital controllers, so setting each at 12 o'clock and looking at the same tone level across all inputs would not really tell me anything. 

I would recommend that you feed tone into each input and set the trim to give you the same level reading.  Then remove the tone and listen to the background noise on each track (one at a time) and see if the noise level is noticeably higher on any one track.  My guess is the noise level is so low that every track will sound dead silent.

I'm not sure why Zaxcom uses the photo cell system for their input gain, but I do know that they sound incredibly good and I'm very happy with the result. 

All the best!

Billy Sarokin

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Am I missing something?  Why don't you just plug in a tone generator and set each trim to 0 (or -10 or -20 or whatever)?  Once they are set forget about them.  They will all be equal.

Billy Sarokin

Well, I suppose I could do that if I had to record sound always from the same source. But I like to be able to go from cart to bag and back to cart in a couple of minutes. That means using the mic preamps at times and then going back to line level. If I intend to use 5 similar condenser microphones in a scene (same model, same gain, right?) all I need to do is set the trim for one of them and set all other 4 inputs for the same value, right? With the Fusion I have to repeat the procedure 5 times.

Now I need to use 6 Lectros. I can feed tone from one of them, line up to one input and repeat the value for the other 5 inputs, right? With the Fusion I have to generate tone from every single receiver and set the trim for each input individually.

Now I want to go back to the cart and line up to the mix buss of my mixer ( + 4 dBu) and 6 direct outs (-10dBV). I have to go over this procedure 8 times (for each input).

With my previous recorder (744T) I just memorized the input gain settings for  +4 dBu/-10 dBv/condenser microphone at normal speech level and was able to go to the input gain page and set all inputs to my taste in seconds. (Although I hate the scrolling thing).

I am not as worried about noise level as I am about consistency and control over my recordings. And I want to be able to be flexible and fast as well.

Thanks for you reply, Mr. Sarokin.

Gabi Cunha

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