Topic: Sound Field 350 / Sound Devices 744T - Ongoing Issue, feedback appreciated

[F0CKER]

Hey everyone..... I'm back with the same issue on my Soundfield.  All the backstory information is in this thread....
 
http://taperssection.com/index.php/topic,105664.0.html

That was about customer service at Sound Field, this is more specific to the problem I'm having, so I thought I should start a new thread.

Where I am today....I received the unit last week and tested it on Saturday, this is the replacement mic and preamp that I used in Las Vegas that worked perfectly.  The unit started locking up again after about 1-2 minutes now, so it's much quicker than before.  After switching settings on the 744 a few different ways (sample rate, bit depth, poly wav, mono wav, etc) and going from B Format to the 744 and Stereo to the 744, no changes, it continued to lock up.  I noticed when the deck locked up channel 1 would always seem to peak as if the channel was overloading, that's when the deck would lock up.  So I thought to try channels 3 and 4 only going line in from the 350 preamp.  The deck recorded fine for 30 minutes or so, no issues.  Promising news...we're getting somewhere.  I then went back to the 1&2 channels to see if it would lock up again, and it did after 3  minutes or so.  The only way to get the rig working together was to power down both the 744 and the 350.   So now I know it's specific to channels 1 & 2 only.

So now I'm thinking I've got a voltage issue.  The only difference between the deck and preamp I used in Las Vegas was the battery supply they gave me.  Using my own batteries the deck locks.  However Soundfield said they tested the battery sled and cable I bought from them (but not my actual batteries) and said everything worked fine.  These are the same Lion type batteries you'd find in a 7xx series.  So thinking it was a voltage issue of some sort and because channel one locked up when the signal in it seamed to peak I decided to enable the limiter just to see what happened.  The limiter seemed to resolve the issue.  I ran at 2 hours of a test file Sun am and it was fine, then I taped Wilco last night, again with the limiter enabled, and again no problems. 

So what's the take here?  Is there a possibility there's some distinct voltage issue specific to my 744 and the 350 that can be causing this?  It should also be noted this same issue happened on a 722 I borrowed.  What effect would the limiter have on the recording that mitgh prevent whatever's making my deck lock up from happening?

Help is always appreciated.  I guess the good news is, I have a band aid, but I still don't know what the problem is.  For the record I emailed Soundfield and talked to Sound Devices to make them both aware.  At  this point I'm going to go to Sound Devices since it seems like an issue with the deck, but is related to the 350 preamp. I think I can justify that logic by saying running channels 3&4 line in wiith or without the limiter worked perfectly.

[Craig T]

I agree, sounds like a 7xx issue.  what a hassle.  maybe you should just dump the 350 and switch to a schoeps doublemidside rig.

[cfox]

did you try the test with AC power connected?

[F0CKER]

did you try the test with AC power connected?

No, I hacked the DC cable I got with the unit to rig a battery and needed the cable.  I've already emailed Sound Field and asked them to send me the batteries I used when I ran it in Vegas, and a mains supply cable as well since mine was "misplaced" so I can test all three to see if the issue replicates.

[F0CKER]

I agree, sounds like a 7xx issue.  what a hassle.  maybe you should just dump the 350 and switch to a schoeps doublemidside rig.

it's a 7xx issue but it's directly related to the 350.  Something between the two is off....no idea what though. 

[baustin]

sounds like some type of power or grounding issue.

as i read through your initial thread, i immediately thought back on an issue that i had some years ago. i used to run EAA-PSP2~>Apogee MiniMe~>Sony PCM-M1. the preamp and the dat deck usually ran off of the same eco-charge battery. when the two units were plugged in, i was unable to control the power on the PSP2 (ie - it always stayed on, the on/off switch was negated). come to think of it, i tried switching the power supplies around and whenever the whole loop was completed by plugging the S/PDIF from the apogee into the sony, the PSP2 always immediately came on. i never felt comfortable with that.

some tests that came to mind...
-running both units off of an AC power source
-running both units off of the same power source (ie - if its possible, one battery)
-running one unit off of battery while the other is on AC? and vice versa
-running st350 into channels 1/2 and a second pair of mics/pre into channels 3/4 to see what happens when unit 'freezes' (ie - do the other 2 channels continue to record?). and vice versa.

[baustin]

also you may want to consider kicking or banging one or both units against something to see if that helps.

sometimes the headlights/brake lights go out on my car and i've found that kicking them usually does the trick.

[Craig T]

I agree, sounds like a 7xx issue.  what a hassle.  maybe you should just dump the 350 and switch to a schoeps doublemidside rig.

it's a 7xx issue but it's directly related to the 350.  Something between the two is off....no idea what though. 

yes, that's what I meant.  definitely something up with the combo, and I guess it could still be something "out of spec" being sent to the 744.  I'd be curious to know how the rig tests out on A/C power.

[rokpunk]

I think I suggested this in the last thread about this issue, but try it using AC power.
Why the limiter seems to solve the problem is beyond me.

[baustin]

maybe a stupid question, but you do have the phantom power turned off on the 744t, correct? whether it would make a difference, i don't know, but i have accidentally turned it back on via the switches above ch 1/2.

[F0CKER]

I think I suggested this in the last thread about this issue, but try it using AC power.
Why the limiter seems to solve the problem is beyond me.

I am, like I said I hacked the AC cable to use the lemo connector for a portable solution.  I don't really need to plug it in ever.  I've aksed SF to send me a new one since I misplaced mine and to also send ther other batteries i used in Las Vegas as well.

[F0CKER]

maybe a stupid question, but you do have the phantom power turned off on the 744t, correct? whether it would make a difference, i don't know, but i have accidentally turned it back on via the switches above ch 1/2.

phantom power is turned off, yes.

[rokpunk]

I think I suggested this in the last thread about this issue, but try it using AC power.
Why the limiter seems to solve the problem is beyond me.

I am, like I said I hacked the AC cable to use the lemo connector for a portable solution. 

is there any chance your "portable solution" is the cause of the problem?
it certainly sounds like a power issue to me, but i'm just going by what i remember from this thread last month.

[F0CKER]

is there any chance your "portable solution" is the cause of the problem?
it certainly sounds like a power issue to me, but i'm just going by what i remember from this thread last month.

Nope, I bagged on building my own and ended up buying from Soundfield.

[F0CKER]

maybe you should just dump the 350 and switch to a schoeps doublemidside rig.

no way dude, I on ly put up one mic and don't even have to worry abotu patterns.  This mic was made for the slacker taper in all of us, especially the one in me.  I would be compelled to sell this one once they release SMS200...it can be powered by any 48V power source.  I'd love to hear the Soundfield matched with a few different pres.

[jimmyrow]

sometimes the headlights/brake lights go out on my car and i've found that kicking them usually does the trick.

That would explain all your car problems lately ba. 

[/hijack]

[T.J.]

maybe you should just dump the 350 and switch to a schoeps doublemidside rig.

no way dude, I on ly put up one mic and don't even have to worry abotu patterns. 

yeah, but the fear of incomplete recordings would nullify any type of convenience regarding patterns.

+T for your troubles focker and keeping a cool head. i'd be freakin' the F' out. tough situation indeed.

[mmedley.]

Just got off the phone with Focker. I did not even know this thread was here until he told me about it. From his explanations on the phone and in here I would bet it is a ground loop issue between the 2 units. The first thing that came to mind is the Schoeps tubes since one of the NT units has to have the "ground lift" enabled when using the same battery to power both NT's. Thanks for that info CFox. This leads me to believe that there is a grounding issue between the units.

I have also read where many people on the SD site have experienced hearing the timecode on their 744t's while others have been lightly shocked when touching their SD units.

Here is a thread specifically that comes to mind for registered users of the SD support site...few posts below for non-registered users...

http://forums.sounddevices.com/showthread.php?t=1580

Just got my 744t back from service and noticed something odd. When plugging in the headphone output to return to my 442, I find that if I touch the "tip" of the 1/8 stereo plug to any of the non aluminum parts of the 744t I can hear timecode on my 442. No other timecode, power or audio connections present...just have the 1/8" cable plugged into the B input of my 442 and then touch the tip of the other end to the 744t.

Charlie,

Tried this with my 744. The only time I heard a hint of timecode was when I put the 1/8" tip right on the tc out pin of the Lemo 5.

Question is, do you hear it normal operation?

Reminds me of the old joke:

"Doctor, it hurts when I do this"

"Then don't do that..."

I do not hear it in normal operation with the cable fully inserted but I find it odd that I've NEVER heard it before in all the times that I have plugged in a return cable and the first time I plug one in when it comes back from the mother ship I hear timecode as I insert the cable when the tip first touches the connector. And as I said...I hear it on EVERY conductive surface of the 744t. So...is this normal or do you think something could be amiss?

Charlie

Matt,

It's very simple. 1/8" in to 1/8" in stero cable connected to B input of 442. I touch the other end to ANY non aluminum metal part of the 744t and I hear timecode loud and clear in my 442 headphone return. When I plug it into the headphone out on the 744t, I hear timecode as it first touches the out ring and it goes away when fully inserted.

Don't know what a recording would accomplish here?

Hi Charlie,
This is not unique to your recorder, as we have duplicated what you are hearing on a 744T recorder here at SD HQ. However, I was only able to hear it when I had a cable connected to the TC Out. Do you have the TC Out connected to a cable?
Under those conditions, TC is audible by touching non-aluminum parts of the chassis such as screws or the outer ring of the HP jack, but it in no way affects recorded program. I also tested this with a 788T, and this does not happen, probably due to the improved design of the 788T, which grounds the chassis much better than previous models.

Charlie,

I asked because all I get on my 744 is ground hum. No timecode at all. I wanted to listen to the sound myself just to see what else might be lurking in there. It was more curiosity than anything else.

Even with a TC cable attached, I don't get TC bleed....

Could just be minor variations among units.

Edit:

Here is a thread about the shocks...

http://forums.sounddevices.com/showthread.php?t=1343&highlight=shock

I was recharging my unit, and updating the firmware etc, when I noticed a few new things.

If I touch the case with a sensitive part of my hand (e.g. the back) I get quite strong electric shocks. If I stroke it I get the characteristic 50 Hz buzzing effect in my fingers.

I did a Repair on the IN drive, 2 errors found, one fixed. Did the same for the CF - 0/0.

Only offered file type is now .wav - has .bwf been ditched?

I had battery charging trouble - four flashes. Disconnected mains, turned off and removed and replaced battery and it sorted itself out. Can I no longer change battery while connected and running?

The manual gives no advice about what to do when this happens - is there a newer manual? I couldn't find one to download.

Best, T.

Hi Matt,

I think it has always done this a bit, just now seems worse.

Your support is many thousands of miles away, and about to get more so! What needs to be done? Something wrong with the power supply unit? I have a separate charger, so if it is life-threatening I may be able to charge my batteries externally, but of course that means the blasted Timecode will turn to gibberish if I get a decent lunch, yes?

You are right, I was charging the unit whilst updating the firmware. From what you say the charge light system still contains features which are now no longer documented in the manual. Are there other such things? I noticed that the new manual was a slightly smaller file. Should I blend it with the old? At the least, the manual needs to tell us to unplug and re-plug when setting the time - I might well not have thought of doing that late on a Friday, and I very seldom have internet access whilst working.

The BWF extension has been removed to remove problems caused by software that doesn't recognize the extension. There was no difference between .wav and .bwf except the extension.

I remember wondering when I first came across this, just who managed to persuade everybody that this was the 'industry standard'. I'm sure it wasn't you guys - I did a film with Nagras which the overseas post-production converted to .bwf, resulting in chaos in the uk cutting rooms. I've personally had nothing but grief arise out of .bwf and wish it good riddance!

Best regards, T.
Reply With Quote

There's nothing 'unusual' about that, Tony. And there is nothing odd about your machine's power supply either. We get the same here with the 722s and their power supplies. (We have over a dozen of them.) Those in the US probably don't notice it because the mains supply is lower, and their higher mains frequency (60 Hz Vs 50Hz) may also make the tingles less noticable.

The reason is because the power supply is a switch mode job. The earth pin on the UK plug (adaptor) of the supply is not connected, so you will have a very high resistance on that. The Australian plug (and all the others supplied for the power supply) only has two pins - no earth pin.

Also because it's a switch mode supply, there is no direct load element such as a transformer inside the supply. The input is usually rectified before being used to drive the oscillator stage, and the diodes doing that probably have a high forward drop, so a DMM is likely to read high across it.

Because there is no earth connection, the output is effectively left floating, so you can get something like half the main voltage to ground, though with no real current. We see a similar thing with many laptops that don't earth their power supply. There is no danger as such, you just get tingles. The 7xx's give an interesting effect though with the clearly noticable buzz as you run your fingers over it, as you mentioned. The effect is simply a 'feature' of the design of the power supply.

If the machine is connected to anything else like a computer, mixer or workstation etc, that has an earth somewhere, then the audio or firewire cable sheilding will effectively ground the machine, so you will not get the tingles. It only happens when the machine is not connected to anything other than it's powersupply, because that leaves the machine floating.

[rokpunk]

Interesting reading above...

It does indeed sound like it could be a grounding issue, which is sort of why I'd like to see a test run with everything powered with AC from a single grounded outlet....even if it's not typically run powered this way in the field. In any case, good luck troubleshooting...+T for your woes.

[muj]

I agree, sounds like a 7xx issue.  what a hassle.  maybe you should just dump the 350 and switch to a schoeps doublemidside rig.

it's a 7xx issue but it's directly related to the 350.  Something between the two is off....no idea what though. 

impedance mismatching?.lol..strangest taper prob i've read about.good luck bro

[F0CKER]

Thanks for the feedback everyone.  After I finish up taping the shows I've got lined up this week I'l be sneding it back to Sound Devices with all the feedback posted here.  Thanks!  I do think it's starting to get narrowed down, and that helps.

[baustin]

sometimes the headlights/brake lights go out on my car and i've found that kicking them usually does the trick.

That would explain all your car problems lately ba. 

[/hijack]

how do you think i get your schoeps capsules working if they make a bad tape? 

[boojum]

F - is there anyone close to you who could lend you a 7xx to run the mic(s) with?  That could help, maybe.  I sure hope you can shoot this bug soon.  It is starting to get to all of us.  I would sure love to see you post a note saying the rig was 100% for each time you used it.

Keep us posted.

[F0CKER]

F - is there anyone close to you who could lend you a 7xx to run the mic(s) with?  That could help, maybe.  I sure hope you can shoot this bug soon.  It is starting to get to all of us.  I would sure love to see you post a note saying the rig was 100% for each time you used it.

Keep us posted.

Actually ran a 722 awhileback when I sent my 744 off to SD because I thought it was a deck issue at first..then the issue happened with the 722 so I was convinced it was a 350 issue.  Now I think it's the 350 and the 7xx series...directly related to the power supply.  They started selling a new power supply a little while back, I think I was one of the first to buy it.  We'll see how it goes, but for now, I'm gonna send the whole rig to SD.  I trust their service standards more...plus I think it's an issue with the deck, as a result of something with the 350....

[boojum]

GB -  Well, SD is a lot closer for one.  And you can call them on the phone for a little hand-holding if you need to.  And they are really good guys out there.  They have always done right by me.  Even when they were tempted to tell me to ship the unit back because I was too dumb to own it.  LOL  Their staff is sharp and easy to get along with.  I sure hope you come out of this all fat and happy.

Cheers

[F0CKER]

boojum, I' ve decided to sell the 744 and get a mod'd R44 instead...too many issues and, frankly, I needed the extra cash too.  So hoepfully my issues will be reoslved with a new deck...and the extra cash repairs the rotting deck at my condo.

It's all about fixing the decks.

[jimmyrow]

It's all about fixing the decks.

Now THAT is funny!!!   +T for getting all your issues (well, at least two of them) solved 

[F0CKER]

Yeah, trust me Jimbo I've got plenty more issues.  This is just the surface.  My life is like a whack-a-mole game lately....I beat one issue and something else always pops up.

All I want is to win the fuzzy bunny eventually.