Topic: Creative/Unorthodox Mixpre 10 (and 3/6) powering options (9V DVD batt & USB A)

[taper420]

I just got my MP 10 II and despite the Hirose input only taking a minimum of 10V, I am intent on getting my copious 9V DVD batteries to work with it, rather than turning to a new form of power. The 8 X AA sled and the L-mount sled indicate that that input will take lower voltages. Upon inspecting the AA sled, it appears that it is not 8X AA in series but two parallel groups of 4X AA in series. So it’s producing 6V on the high end and as low as 4V on the low end (4X NiMH rechargeables will be around 4V right before dying).

So what does this mean? It means the sled input can take anywhere from around 4V to 9V (an L-mount). So then, one of the solutions would be to buy the L-mount sled, and a dummy L-mount with 9V DVD battery plug (4.0mm X 1.7mm or a locking 5.5mmX2.1mm and one of my battery mods).


Another solution that costs a bit less would use the AA sled we already have. Two sets of 4X AA dummy batteries with a wired DC input on each set should do the job. I found these sets that have a USB A on one end that takes in 5V 2A and puts out 6V up to 1A.

What I’m going to do is chop off the USB ends and attach T3 connectors so I can swap out any plug I want (USB A, 4.0X1.7mm, locking 5.5X2.1mm). That way I can run it off the 9V DVD batts or any USB A battery that has at least two outputs that will output 2A each.





I’ve not tested max current draw with all phantom on, with either the USB or 9V batts, but the unit does power on just fine so far from a USB source when plugged into the wall (spec on power brick is 2.4A per output), but fails during power up when both USB are plugged into a dual output battery that is supposed to have the same spec as the wall brick (EasyACC PB20000MS). Power up is successful when plugged into the EasyACC and a 2nd USB battery, and also when just plugged into the 2nd battery with both plugs. The 2nd battery is a shell that takes 8 X 18650 cells, model: QD188-PD.




Further testing will demonstrate the limits of these batteries, if any, while running at max spec on the MP 10 II. It dawns on me that replacing the boost converter USB that takes 5V 2A and outputs 6V 1A and replacing it with a regular USB A plug might help. Unless there's some kind of handshake issue, 5V at 4A is better than 6V at 2A. Although there may very well be a handshake chip that is needed to allow power over 1A. So, there may be a limit using USB, but I’m confident that two 9V DVD batts in parallel (if not just one) will run this thing just fine. I will update this thread with my progress.

[taper420]

And here we have it... a Mixpre 10 II running on a pair of 9V DVD batteries...


And here we have it running on just one.


I am using just one set of the dummy batteries, so only 4 of the AA slots in the sled are being used. This works because the two sets of 4 are in parallel, so if you have just one set of 4 that is supplying enough current, it will work. I did this because I already have a parallel battery cable with a T3 wired up for my V3. So I just swapped out a better, jacketed cable and put a T3 onto the end of the AA dummy. That matches up to the parallel cable that is made from two cables that came with the DVD batteries. Perfect fit.

It is drawing about 800mA, split unevenly between the two batteries (this is common when running two batteries in parallel like this... it's actually preferable because one will die first and give you a chance to swap it). Given the headroom left on each battery, maxing out the specs on the MP should be well within the range of output, but I'll be doing testing to be sure. Of note, we can see by comparing the meter readings on the 5V and 9V batteries, the MP is using about 8W on the 5V and 7W on the 9V, so those boost converters are eating about a Watt of energy (although there is a boost or buck converter inside each battery that I'm not accounting for, so it's not a cell-level comparison of used energy).

[vanark]

I applaud your creativity and ingenuity! I'm sure it is an interesting puzzle.

I'm not sure I'd every run it in the field myself. The SD MixPre devices have a history of being a bit finicky about power (at least what I've heard), so not sure I'd run anything that wasn't a solid power source. It is such a nice piece of gear and presumably you have the mics to go with it. I say kudos for figuring it out, but time to retire those 9V DVD batteries.

[taper420]

I get it, but I think the DVD batteries get a bad rap. Think of how solidly these things have performed in our community for nearly 2 decades, and I'm still refurbishing them for tapers to this day! That's the thing, I've had dozens of these things open and I know how they work and what's inside. When used in spec, these things perform as good or better than anything else out there. The original cells were top shelf (for their day) either Panasonic or GP 2000mAh. If your device can run solidly on a 9V source, it is a solid power supply, especially after being refurbed with new Panasonic 3200mAh cells (obliged to mention having the meter button replaced and optional locking output port - services available, pm me).



I've also had other power supplies open and they are either inferior or just as good, but not, IMO, better. The larger Sony L-mount batteries have the same number of 18650 cells. If you purchase off-brand, it's a crapshoot what cells you get.  Sony brand batteries usually top out at 2600mAh per cell. I've not had any experience with the Talentcells a lot of tapers have moved to, but I can tell you that off switch would make me nervous as hell. The DVD batts are instant on with no lower threshold (tested on a 20mA LED). They also have discrete inputs and outputs and a diode on the output so they can be run in parallel (or hotswapped) without one battery sapping or frying the other... Not something you always see.

Other more "professional" batteries (D-tap for instance) are just a fancy plug on a case of 18650s, usually extremely overpriced, and if reasonable, filled with inferior cells. The things is, the majority of batteries that are used for devices in this power range are just cases around 18650s. I would much rather have my own choice of quality cells. And there's nothing wrong with the electronics inside the DVD batteries, they're better than most I've seen. I've used them to power a range of devices from Tascam audio recorders, the V3, Canon video cameras, Atomos video recorders (and any other device with an L-mount), and now the Mixpre. I see no qualitative reason not to keep using them, as they have performed superbly for dozens of years. As for the MP being finicky, the sled input is clearly designed to take from 4-9V. A fully charged L-mount puts out right around the top of that range, so I don't see much of a difference between their use. It's just a differently shaped case for 6X 18650s. And I tell you, I think that's a lot more solid and reliable than running 8X AAs, even lithium, especially with the ability to run in parallel. If this thing can run on 8 alkaline AA batteries (within spec and available in the menu but not recommended for long periods), running it on the DVD batteries will be a breeze.

[Justy Gyee]

curious on where you're picking up these HQ cells?
ive got a couple old dvd battery packs that id like to get up and running again.

[taper420]

curious on where you're picking up these HQ cells?
ive got a couple old dvd battery packs that id like to get up and running again.

I shop industry surplus. Many of my cells come from surplus modem and medical supply batteries that were kept in stock for emergency use, but never used and had to be replaced after 3 years. I test them and make sure they function to spec and the rare dud gets chucked. Any that perform under spec but are not dead get used for non-critical applications. Batteryhookup.com is my usual supplier, but you have to watch them and look for deals. Also, make sure you read descriptions because some are used surplus, and those are a crapshoot. Their inventory is constantly changing.

If you'd rather have someone else handle the dirty work, click on my sig and check out my services. I currently have LG 2600mAh cells and possibly a few Panasonic 3200mAh cells left in stock.