Author Topic: The mackie DL1608 white noise saga continued..  (Read 76763 times)

robbocurry

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Re: The mackie DL1608 white noise saga continued..
« Reply #15 on: July 23, 2014, 01:22:40 AM »
Hey WK, no offence taken at all, this is a pleasant break from work!
You maybe guessed already, but I try to look for the good side in everyone.
That's why I'm inclined to give Mackie the benefit of the doubt regarding their awareness of said problem.
I must admit that I don't recall the white noise being an issue early on in this (or the Mackie) forum.
Maybe my perception of time is skewed, I just see it as a more recent problem?
Anyway, back to the other (real) homework I have :thu: ;)
The older I get, the better I was!

WK154

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Re: The mackie DL1608 white noise saga continued..
« Reply #16 on: July 23, 2014, 04:25:50 AM »
Good policy to have, lower blood pressure etc.. I remember reading about it 3-4 month after I received my DL that would put it about November - December 2012. I never used the feature cause I never saw the point of loading up the iPad with music since I already had my wife's iPod which was enough to maintain. Never needed more than about 10 mics so I had channels to spare.
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Jerrylee

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Re: The mackie DL1608 white noise saga continued..
« Reply #17 on: July 23, 2014, 07:35:29 AM »
Very impressive, I heard a demo of a DVA system and it sounded great. That's a lot of boxes for someone to hump around:)

Hey robbo I am glad you heard a dva system and said it sounds great. I had to base my decision on things I have seen online. Reviews, YouTube, etc. I should have my whole system delivered with the next several weeks. I also was able to contact some national acts that had played some of my upcoming events in the past. I needed to know if the setup would be rider friendly. All said yes. Most of the acts I will be working with are not too picky. I called the ones from the past that I was told are picky. So if I do run into one of them I will be safe. My first big event is not till November. I am planning on doing a gig for a friends band who has a small amphitheater gig. They are stoked for me to do it for them. This way I can test it all before November.

4mal

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Re: The mackie DL1608 white noise saga continued..
« Reply #18 on: August 23, 2014, 06:51:44 PM »
I picked up a dl806 for corporate speech gigs and small /low input countsensemble gigs.  Nice little mixer but I also got the white noise burst using an iPad 2 (wifi and 3G), 32 gig. IOS 7.1.2.  I didn't track it back to the disconnect.  Good to know that I should avoid that.

Question is if I kill the music, via double tap of the home button and kill the music as a background task, can I then disconnect w/o the noise ?  If so, can I re launch the music  while wifi connected to the 806 ?  I could live with that though I would prefer not to have to ...

Thanks!

Keyboard Magic

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Re: The mackie DL1608 white noise saga continued..
« Reply #19 on: September 22, 2014, 07:35:18 PM »
I never experienced the white noise problem with my former DL or the school’s, because I never played audio with the docked iPad. I didn’t want to run into that particular issue, to avoid headaches at gigs. I always plug my iPod into channel 15/16 for walk-in music etc. I always run my iPad undocked and keep a spare one also wirelessly connected, just in case. And keep a spare old style mixer for backup.

The issue here is you should be able to play audio with a docked iPad. That’s why Master Fader has an iPad channel. You should be able to run an iPad docked all the time if you have to without dropping sync. It was designed that way from the onset. Obviously Mackie didn’t do thorough enough real world testing of the mixer/iPad combo. Or enough quality control. They obviously, even though they have a website for suggestions, didn’t listen to everyone. This can be compared to selective hearing, only deal with what you want to hear.

Mackie shouldn’t be taken to task for problems that occurred after the fact. They should be scurrying to correct these issues. But like I’ve said “adnauseum” It’s a good bet that the current platform is being swept under the carpet, warts and all, to be superseded by the upcoming release of the DL32 and its spinoffs. I think Mackie is hoping that we will all be so wowed by it we line up for hours (can you say new iPhones?) to get the latest new toy. “Out of Sight, Out Of Mind” (Mackie or Us?)  ::)
« Last Edit: September 23, 2014, 12:53:49 AM by Keyboard Magic »
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Re: The mackie DL1608 white noise saga continued..
« Reply #20 on: September 23, 2014, 06:39:00 AM »

Mackie shouldn’t be taken to task for problems that occurred after the fact. They should be scurrying to correct these issues. But like I’ve said “adnauseum” It’s a good bet that the current platform is being swept under the carpet, warts and all, to be superseded by the upcoming release of the DL32 and its spinoffs. I think Mackie is hoping that we will all be so wowed by it we line up for hours (can you say new iPhones?) to get the latest new toy. “Out of Sight, Out Of Mind” (Mackie or Us?)  ::)

I've used my DL for quite a few gigs now, and for the most part like it...generally speaking.

In my 25 years in the live music industry down here in Australia I've met a Lot of other sound engineers over the years and mackie has been one brand (out of a handful) that has always gained negative conversation due to various issues those many colleagues have experienced. (I've never owned a mackie product before this thing)

I love the simplicity of the UI.
I love being able to stand at a mic and adjust the EQ in real time (this would be my favourite DL feature)
I love not having to run a multicore anymore.
And I love having 6 aux send for monitors.

Does it sound as good as my previous analogue mixers? Not in my opinion. But it's not far behind, and certainly not a deal breaker.

Long story short having experienced the white noise issue, and watching their inability, or reluctance to get it sorted is enough to sway me well away from any future mackie purchase.

So if mackie is hoping that they will keep current DL customers in the hopes they will "upgrade" to the DL 32, I can positively guarantee I'll never be embarrassed by their half arsed products again.

I will use this current DL1608 until it no longer functions due to whatever reason, after which I'll wash my hands of the mackie brand and move to some other brand who actually address any issues that arise.

Keyboard Magic

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Re: The mackie DL1608 white noise saga continued..
« Reply #21 on: September 23, 2014, 02:06:06 PM »
Hi 4mal,

Welcome to the forum.  ;) I’ve never experienced the white noise issue, like I mentioned in my post, but I would think that in the real world if you killed the app completely it should stop the white noise. Theoretically you’re eliminating the source and should be able to restart the app. Don’t quote me though. There are so many here with way more tech experience than I have, in this area, who can give you a definitive answer. I hope they chime in on your request.

Obviously with the 806, eating up 1 or 2 channels for audio playback is not an option for you. But it would eliminate the white noise issue. Even though you shouldn't have to do that. It should work as it was designed. Darn It. (insert your own colorful metaphors here) ::)
« Last Edit: September 23, 2014, 03:54:24 PM by Keyboard Magic »
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Kevin

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Re: The mackie DL1608 white noise saga continued..
« Reply #22 on: September 23, 2014, 02:22:37 PM »
I saw the white noise problem once - about 18 months ago, when I was trying to get a 30pin extension cable to work. It sounded like the output from my RTA was on, which really threw me for a loop until I realized that it was coming from the iPad. I havent had the problem since, so I had pretty much forgot about it. Recent findings by WK154 and Roadrunner make me fairly sure that this problem is just another symptom of the same root cause, namely a noisy iPad fast charge circuit on the DL.

Luckily there are a couple of workarounds, which is probably why I never saw it again after 18 months ago:

a) if you have a newish iPad, fully charge it before each gig and dont dock it if the battery charge is below 90 percent. That keeps the DL's charge circuit in trickle charge mode. If the DL's charge circuit switches over to fast charge mode, it gets noisy and random bad things can happen

b) if you have an older iPad with a faded battery, you might need to get a cheap 30 pin extension cable and cut the 5v power line from the DL (pin 23).  Use the cable to dock your iPad. That takes the DL's noisy circuit out of the picture completely as well as allows you to put a protective case on your iPad.

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Re: The mackie DL1608 white noise saga continued..
« Reply #23 on: September 23, 2014, 03:33:06 PM »
I saw the white noise problem once - about 18 months ago, when I was trying to get a 30pin extension cable to work. It sounded like the output from my RTA was on, which really threw me for a loop until I realized that it was coming from the iPad. I havent had the problem since, so I had pretty much forgot about it. Recent findings by WK154 and Roadrunner make me fairly sure that this problem is just another symptom of the same root cause, namely a noisy iPad fast charge circuit on the DL.

Luckily there are a couple of workarounds, which is probably why I never saw it again after 18 months ago:

a) if you have a newish iPad, fully charge it before each gig and dont dock it if the battery charge is below 90 percent. That keeps the DL's charge circuit in trickle charge mode. If the DL's charge circuit switches over to fast charge mode, it gets noisy and random bad things can happen

b) if you have an older iPad with a faded battery, you might need to get a cheap 30 pin extension cable and cut the 5v power line from the DL (pin 23).  Use the cable to dock your iPad. That takes the DL's noisy circuit out of the picture completely as well as allows you to put a protective case on your iPad.
Kevin perhaps I didn't elaborate enough on my recent current draw test or you missed the implication, but there is no trickle charge at 100% iPad battery level, it's a full on charge at around 1.2 amps which then slowly increases to 1.5 amps at which time the DL switches to constant current (limiter kicks in) mode 0.5 amps. Far from your assumptions. This may also be detrimental to the iPad battery but from my measurements the Ipad is receiving the current. but because in the long run it still looses charge it may not be all that bad (iPad uses more than the DL can provide) unless Apple has a safety in place to prevent excess charging. The DL is the charger and it determines charging current. This is the basis on which I believe that noise is not an issue since the iPad receives the noise for over 2 hrs. without a sync problem.

Welcome 4mal. As to your question: unless you have a kill switch to disconnect speakers you won't want to spend all that time with what you stated. Killing the background task will have no effect on the DL, it's off doing it's own thing. Powering off the DL gets it's attention and stops the noise not something you would want to do live but you may not have a choice. Terminating MF may stop the sound but not if you've lost sync. An un-docked iPad may be able to control it.
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Re: The mackie DL1608 white noise saga continued..
« Reply #24 on: September 24, 2014, 04:01:20 AM »
WL154 - I read the results of your current draw test and believe that I understand most of the implications, one of which is that you might benefit from a short primer on how LIon fast charging works, so that we can continue to make some headway on this problem my friend:

If an LIon battery is below 70 - 80 percent capacity (depending on exact chemistry), it is always charged starting in Constant Current (CC) mode,  until the voltage gets to about 4.0 to 4.2v (again these numbers vary a bit depending on chemistry and whether you are optimizing for battery capacity or longevity). All LIon fast chargers do this, whether they are 10W or 80KW

So if you saw your (calculated) current to the iPad start at 1.2 amps and increase to 1.5 amps at 80 percent, that is a clear sign that the DL is not actually directly controlling the charging .  Most likely the DL just supplies a (supposedly) steady 5V and there is another circuit which is actually in the iPad, most likely also using another buck switcher to supply the battery with a constant current until the voltage comes up to ~4.1V.  As the battery voltage rises from say 3.3V (fairly well discharged) to 4.1V (mostly charged), the charge current to the battery stays the same, (probably around 1.7A, going by your numbers), but the current draw from the 5V voltage source on the Mackie increases. The actual charging buck switcher in the iPad has to pull more increasingly more current from the 5 volt rail provided by Mackie, in order to deliver a constant current source to the battery.

So - if you saw the current increase to the iPad as the battery state of charge increased, that is a sure sign that the actual battery charging regulator is on the iPad, not on the DL. No LIon charger increases the current during the CC phase. The DL must just supplying a dumb 5V rail to the actual charging circuit - which may be a good thing for our purposes, because a dumb 5v rail is usually simpler and easier to clean up than a variable voltage regulating circuit.

Now, once the battery voltage comes up to about ~4.1V, the charging circuit will switch from fast CC mode to constant voltage (CV) mode. During CV mode, the charging circuit will hold the battery voltage to ~4.1v and the current will decrease from ~1.7A down to almost nothing. The CV charge stage is terminated when the current reaches a small value, usually something like 0.02C, or in this case about 40mA. Beyond this point, the charger will stop, monitor the voltage, and if it drops below a certain threshold (usually 0.05 below the CV cutoff), a small "trickle" charge is periodically supplied to keep it up to full charge.

That is how LIon battery charging works in a nutshell. Keep in mind that you are never going to see a current as low as 40ma coming from the DL, because in addition to keeping the battery topped off, the 5v rail is also what is powering the iPad. So final current will be much higher than 40ma.

What is interesting in your case is that you reported a sudden drop in charging current, from 1.5 amps to 0.5 amps to the iPad. That is not how the CV stage of LIon charging works. Typically, you will see the current reduced in the shape of an exponential curve, from CC current (~1.7A to the battery, ~1.5A from Mackie's 5V supply) all the way down to almost nothing, over a period of about 90 minutes. Not a step decrease like this.

When you said that the unit "failed" at 80 percent when the current dropped to 0.5A, are you saying that Master Fader lost synch at this point? If so, then it seems to me that the failure could be one of three things:

a) If the 5V regulator circuit on the DL is not adequately sized, as the charging circuit on the iPad pulls more current, the rail could be getting hogged down, which will make it increasingly noisy. As voltage on the battery comes up, the current required from the 5V rail in order to keep the battery in constant current mode goes up, and the noise increases until it starts affecting data signals and something hiccups. This is actually the best case scenario because it ought to be relatively easy to fix a simple 5v regulator circuit

or (more problematic)

b) the fact that the current dropped right to 0.5A when the failure occurred is suspicious to me. Because that is the max current supplied under the normal USB spec. I havent delved too much into the apple charging particulars, but my limited understanding is that some USB signaling is involved which allows the iPad or iPhone to tell the wall wart "give me all the juice you can" instead of the normal 500mA. The fact that the current dropped right to 500mA when things went south is a troubling sign to me that Mackie might have used the same chip that Apple uses in their wall warts to supply the 5v rail to the iPad. And when the MF synch dropped, the USB signal from the charging circuit also dropped and the supply circuit on the DL went into dumb "I'm just a standard USB charger" mode. There really should be no need for Mackie to have used the apple chip, because there is no chance that anything other than an Apple product will be using the DL's USB circuit, hence no need to support the published USB spec, just give the device as much current as its onboard charger wants. However Apple is pretty good about bamboozling manufacturers into buying chips that they dont really need. In all likelihood, the apple chip can be removed and replaced with a simple 5v 2A regulated supply without too much fuss, but it wont be a pretty mod, and definitely not a drop in parts replacement or an easy factory BOM change like (a) is likely to be. This might also explain why Mackie hasnt fixed this yet - because its not really their problem. Under normal wall wart conditions, apple probably doesnt care if their regulated 5v is noisy as hell, but put it in a cable with a lot of other control signals and bad things can happen. Still this is fixable in the field.

or (worst case)

(c) Both MF and the iPad's charging circuit are both using the same USB data lines for control, with at least two devices on the DL (Apple's 5V supply chip, DL's control interface) and a single host controller, with multiple application interfaces (charge circuit control FW and MF) on the iPad. When the iPad battery needs more than 500mA of current, both the charge circuit and MF are using the same USB lines. In theory there is nothing wrong with this. The USB protocol supports multiple device and host endpoints on the same bus, but in practice, this can get tricky. I've worked on host mode USB drivers before and they can be a real bitch to get to be 100 percent reliable even when interfacing to known devices. In the case of Apple, there probably are not too many instances where an iPad will be both charging and doing some other critical control data over same USB lines at the same time, so Apple may not have spent a lot of time beating on their USB host controller firmware. In that case, there may have been a data collision in the USB host driver, which would have occurred on the iPad and it could take out both MF and the charging circuit. That would explain why MF drops out and the current drops to 0.5A at the same time (assuming that is what you saw). That would also explain why Mackie is having such a hard time fixing this. Apple is probably telling them that they are not using the USB host driver correctly, but the truth may be that Apples USB host driver has holes in it.

Fortunately for everyone having these problem, in the short term, no matter what the cause (assuming one of the above), the workaround is the same. Keep your iPad fully charged, so that it doesnt need to draw more than 500mA from the DL to charge its battery. Or, if your iPad's battery is old and doesnt hold a charge well, get a cable and cut pin 23





« Last Edit: September 24, 2014, 04:44:09 AM by Kevin »

WK154

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Re: The mackie DL1608 white noise saga continued..
« Reply #25 on: September 26, 2014, 04:29:30 AM »
Kevin I don't need a refresher course in Li recommended charging procedures, you're preaching to the choir. To make some headway on identifying this problem we first need FACTS. As I recollect you have certainly not shared any with us here. Perhaps it's all about conjecture. For everyone Else's benefit there are two regulating circuits in the charging system, one in the charger (DL) which is a Constant Voltage circuit  with a limiter, the other a protective circuit (iPad) that are in all Li batteries I'm aware off. The extend to the sophistication of the battery protection/regulation varies widely.
Apple has used Li-polymer batteries as far back as I can remember. The rating on these is 3.7-3.78V not 4.1V. Apple also stated that the 100% indicator is really not that but in close proximity to allow for a charge/discharge cycle to happen to accommodate permanently attached chargers. I would suggest that you read the USB Battery spec V1.2 (part of the USB 2.0 spec)  http://www.usb.org/developers/docs/usb20_docs/   I mentioned before and pay close attention to fig. 4-1 I'm sure it will answer a lot of questions. I'm not trying to create an issue here it's part of the FACT finding. As I see it until we have more measurements and closer to the subject we should all limit our conclusions. I will find some time next week to explore the cable measurements which will certainly be quite specific.  Since you're a contract engineer perhaps you could also take some measurements. I do have schematics on the  reference design by Apple's Engineering co. iWatt. http://iwatt.com/wp-content/uploads/2013/07/EBC10007_Reference_Design.pdf  According to people that have taken the charger apart have stated that there are very minor differences. This is for a DCP (wall wart)  not a CDP which is what a DL should be. The specs are somewhat different but the constant 5V to the current limit are similar, the spec clearly defines that. iWatt designed the DCP and possibly also the CDP (Apple secret). iWatt design their own IC's. Here is another company in that game.  http://www.maximintegrated.com/en/app-notes/index.mvp/id/4803
Some useful info from them. Perhaps we can get closer to identifying the problem without Mackie's help.
« Last Edit: September 27, 2014, 02:12:50 AM by WK154 »
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Re: The mackie DL1608 white noise saga continued..
« Reply #26 on: September 30, 2014, 12:14:39 PM »
So, just a random thought here from a newbie to this forum and the DL1608, but a long, long time "sound guy" and musician and broadcast engineer. This is in no way intended to throw gasoline on this fire, nor to make "excuses" for anybody involved. It's just meant to offer some food for thought.

I've noticed random spurts of audio interference from wireless devices, particularly those with GSM cellular features, although some CDMA-equipped devices do it as well. Here in the states, phones with AT&T service can cause audio system noise even when located 15-20 feet away from audio equipment. The noises have varied from random "squelch burst" white noises to sounds that reminded me of old dial-up modems. Sometimes, the sounds last only a couple of seconds, and sometimes, they last for quite a while. Proximity of the wireless device to the audio gear plays a role as well.

I have also noticed with my iPad Mini that, when it's connected to an amp via the "headphone" output, that moving my fingers across the display sometimes causes noises on the output.

I've noticed these noises with a variety of audio systems -- both analog and digital -- from Mackie, Allen and Heath, Presonus, Behringer, the cheap table radio over on my kitchen counter, my wife's car radio (but not mine, go figure) ... you get the point. Pretty random, but always pointing back to the cellular device, and most often, a GSM cellular device.

When the DL1608 was designed, wireless routers were not available in the 5GHz frequency band, and there may be some unknown issue there, especially with placing the router within inches of the mixer hardware. The same may be true of 2.4GHz, for that matter. And, there are a myriad of other cheap wireless and digital devices that could be spewing out random noise in the environments in which we work -- cordless telephones, wireless headsets and short range paging devices are now staples of the food services industry; the bands we're doing sound for are using stacks of wireless low-priced wireless gear in the VHF, UHF and now 2.4GHz bands, and stacks of plastic-cased digital effects units, all with high-frequency clocks and processors banging away. While these devices may be from well-respected brands like Shure and Senneheiser, I can pretty much guarantee that a $400 Shure PG- or BLX-series wireless system is not built to the same standard as their UL- and DL-series models. Oh, and let's not forget the trucker yammering on his hopped-up CB unit on the highway behind the venue.

So, as a tech and an engineer with quite a bit of experience in the "real world," I can certainly see a number of places where spurious noises can and do enter our audio systems or mixers. I know for a fact that Allen and Heath's iLive system is susceptible to some of these same sources of interference in certain circumstances, and I fully expect that every audio system may have some level of susceptibility to outside factors.
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Re: The mackie DL1608 white noise saga continued..
« Reply #27 on: September 30, 2014, 12:27:32 PM »
Kevin I don't need a refresher course in Li recommended charging procedures, you're preaching to the choir. To make some headway on identifying this problem we first need FACTS. As I recollect you have certainly not shared any with us here. Perhaps it's all about conjecture. For everyone Else's benefit there are two regulating circuits in the charging system, one in the charger (DL) which is a Constant Voltage circuit  with a limiter, the other a protective circuit (iPad) that are in all Li batteries I'm aware off. The extend to the sophistication of the battery protection/regulation varies widely.
Apple has used Li-polymer batteries as far back as I can remember. The rating on these is 3.7-3.78V not 4.1V. Apple also stated that the 100% indicator is really not that but in close proximity to allow for a charge/discharge cycle to happen to accommodate permanently attached chargers. I would suggest that you read the USB Battery spec V1.2 (part of the USB 2.0 spec)  http://www.usb.org/developers/docs/usb20_docs/   I mentioned before and pay close attention to fig. 4-1 I'm sure it will answer a lot of questions. I'm not trying to create an issue here it's part of the FACT finding. As I see it until we have more measurements and closer to the subject we should all limit our conclusions. I will find some time next week to explore the cable measurements which will certainly be quite specific.  Since you're a contract engineer perhaps you could also take some measurements. I do have schematics on the  reference design by Apple's Engineering co. iWatt. http://iwatt.com/wp-content/uploads/2013/07/EBC10007_Reference_Design.pdf  According to people that have taken the charger apart have stated that there are very minor differences. This is for a DCP (wall wart)  not a CDP which is what a DL should be. The specs are somewhat different but the constant 5V to the current limit are similar, the spec clearly defines that. iWatt designed the DCP and possibly also the CDP (Apple secret). iWatt design their own IC's. Here is another company in that game.  http://www.maximintegrated.com/en/app-notes/index.mvp/id/4803
Some useful info from them. Perhaps we can get closer to identifying the problem without Mackie's help.

Just a couple of additions here...

All LiPo cells are rated at a nominal voltage of 3.7V. The MAXIMUM allowable charge is 4.2V, with an optimal charge being 4.1V. An individual cell works best if not drained below 3.0V, and internal damage to the cell will occur below 2.7V.

Not all LiPo cells have built-in or built-on protection circuits, although those used in cellular phones and similar devices generally do. However, there are many, many LiPo battery packs out there with no protection on the cells that rely on more sophisticated chargers that monitor and control the charge to each cell in the pack. This kind of control allows for optimal charging of each cell in the pack, which can prolong "run time" and overall battery life.

If you look at the pack, and it has more than two connection points (or a multi-pin connector of some sort), then the protection is probably external. Most laptops, for instance, that use Li battery packs us external protection and monitoring.

batteryuniversity.com is an excellent source of information on all types of batteries, including LiPo, LiFe and Lithium-Ion.
Geren W. Mortensen, Jr.
Westminster, Maryland, USA

WK154

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Re: The mackie DL1608 white noise saga continued..
« Reply #28 on: September 30, 2014, 04:49:05 PM »
gerenm63 welcome aboard.
my iPad 3 LiPo cells are rated at 3.78V by the manufacturer so not all are 3.7V. I didn't state the regulation/control of the battery is part of the battery but certainly part of the battery system. I should have been more specific. As I pointed out there are many levels of protection but all are protected, unless the company wants to be out of business overnight. We have pretty much ruled out outside RF as the cause of the noise. The sync problem clearly is a Mackie fixable issue.
« Last Edit: September 30, 2014, 05:39:40 PM by WK154 »
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Re: The mackie DL1608 white noise saga continued..
« Reply #29 on: September 30, 2014, 09:57:21 PM »
gerenm63 welcome aboard.
my iPad 3 LiPo cells are rated at 3.78V by the manufacturer so not all are 3.7V. I didn't state the regulation/control of the battery is part of the battery but certainly part of the battery system. I should have been more specific. As I pointed out there are many levels of protection but all are protected, unless the company wants to be out of business overnight. We have pretty much ruled out outside RF as the cause of the noise. The sync problem clearly is a Mackie fixable issue.

Thanks for the welcome, WK!

In another part of my life (what? I have a life? Or, do I have several? I don't know some times) I spend a lot of time dealing with battery systems. A 3.78V cell is probably actually a lithium manganese cell. And, I probably should have been more specific, too. The generic term LiPo is generally used in the industry to refer to Lithium-Ion Polymer, a variant of the standard Lithium-Ion cell that has been slightly altered so that it can be built to shapes other than cylindrical. Unfortunately, a lot of these different cell types get lumped under the generic term LiPo, and that's where a lot of problems come in. Assumptions in the case of lithium-based batteries can be extremely dangerous.

As far as ruling out RFI, it's some sneaky stuff. RF energy is everywhere, all the time, in constantly changing quantity and quality. And, as I said, we work in environments that are rife with it. And something as simple as an intermittent pin 1 on a mic cable can open the door for it to come charging into our audio systems. I've also heard all kinds of strange noises come from portable devices like iPhones and iPods, whether connected via Dock/Lighting connectors, or the headphone/line audio output.

I've not yet experienced the sync issue. My DL1608 is a B-stock/demo unit with a 30-pin Dock connector that I recently acquired from my local Mackie rep., who is also a long-time friend. His firm has used it at trade shows and various other demos without incident (I'm guessing he's expecting a DL32R soon, which is why he could part with the DL1608 so readily). As well as being a friend, he's also a brutally honest sort, and I know that if he felt I'd have any problems with a DL1608, he would have shoved me hard to go in a different direction. He's done that before, including telling to not buy certain items that his firm reps.

I should probably put some of these goings on to him, and see what his take is. He may be able to shed some insight. I'll report back when I can.

Cheers!
Geren W. Mortensen, Jr.
Westminster, Maryland, USA