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post #691 of 2631
Quote:
Originally Posted by Happy Camper View Post

There have been plenty that have used them on a speaker amp. Just be responsible with the volume control.

Yeah i just did some googling and it looks like i should be fine with my quality integrated i have. Thanks!

post #692 of 2631

Jan Plummer will be shipping my MG3 on Monday.  tongue_smile.gif   His resistor box will follow a week later.  

 

The TBI website mentions the option of getting Cardas binding posts.  I had no idea what these cost, so was surprised when Jan told me they are a $150 option for the MG3.  I don't think he's marking them up at all.  Apparently, they are expensive, everywhere. I just wanted a 5-way terminal, so that I could use banana plugs, but I will make due with the MG3's standard equipment.  It would have delayed shipment by another week, too. redface.gif  Update:  Per Gary in MD's post below, the default MG3 binding posts are actually 5-way (and thus, can accept banana plugs.)

 

 

Battery power is clean-sounding power!

 

I haven't discussed it with Jan yet, but I'm thinking of running the MG3 on a 24V battery back - instead of using a 24 AC adapter or the internal 12V battery compartment, which holds 8x AA batteries.  

 

I could use lead-acid gel cells, but they're heavy and bulky (low energy density) compared to LiPo packs.

 

I've been using LiPo packs with my Meier Stepdance for almost three years and really love their capacity, form factor, light weight (density) and the various voltages you can achieve with the right number of cells in a pack.

 

LiPo battery packs contain 1 or more cells, with each cell having a fully discharged voltage of 3.0V, a maximum voltage of 4.2V, and a nominal, rated voltage of 3.7V.   This last figure is used by manufacturers to specify the total voltage of their packs, such that a 1-cell Lipo (also known as a "1S," for some reason) is rated at 3.7V, where, a 3-cell LiPo pack (a "3S") is rated at 11.1V (three cells x 3.7V each).

 

But you have to account for the fact that, when fully charged, each cell will be at 4.2V, thus a "3S" battery, rated at 11.1V, will actually supply 12.6V when fully charged, tapering down as it discharges, where you should discontinue use once it reaches 3.0V per cell (or risk permanent damage to the LiPo pack).  

 

The TBI Millenia MG3 can handle 24V, so I'm thinking of using this "6S" LiPo pack as an external power supply:

 

 

 

When fully charged, this battery will produce 25.2V (six cells x 4.2V).  Notice that the label reads "22.2V 25C".  "22.2V" comes from the nominal rating of 3.7V per cell.

 

"25C" refers to the LiPo pack's maximum discharge rate - how many amps you can pull continuously, without overheating the pack.  To calculate the maximum number of amps that can be pulled, just multiply the mAh rating (the total capacity of the pack) by the C rating.  So, for this pack, that's 3800 * 25 =  9500 mA or 95 Amps!  At 25.2V, this battery can handle a 2,394-Watt load (imagine 24 one-hundred Watt light bulbs)!

 

Needless to say, the MG3 won't be pulling anywhere near that much power, but I certainly won't have to worry about the battery pack's internal resistance.  biggrin.gif  

 

 

 

I already use this Thunder AC6 charger (just $43.95 at HobbyPartz) - with which I can fully charge a 6S pack to 25.2V, then, discharge it down to 24.0V, before using it with the MG3.  I'll be asking Jan, however, whether or not he thinks the MG3 could handle 25.2V, keeping in mind that the pack will soon discharge to 24V or less as it's used.  Update:  Gary in MD has written (in a post below) that Jan Plummer says the MG3's DC input must not exceed 27V, so I won't have to worry about pre-discharging a fully charged 6S LiPo pack down to 24V from 25.2V. before using it with the MG3.  Pre-discharging is an extra step (hassle) I won't have to deal with, now. Joy!

 

The AC6 is one of many so-called "balanced chargers."  The LiPo packs have two sets of cables coming from them - one set is for discharging (having just one red wire and one black wire) - the other set is for charging (having a single ground wire that's common to every cell in the pack, plus a "hot" wire for each cell).  When you want to use the battery pack, you just leave the charging cable disconnected, pulling power from the two-conductor cable.

 

When charging the LiPo pack, you connect both sets of cables, but the multi-conductor cable is used by the intelligent charger for "balance charging" the pack by charging each cell independently, such that they all come to 4.2V and no higher.  If you were to charge the pack through the two-conductor discharge cable, you could easily force one or more cells to a voltage higher than 4.2V, while other cells are dragging their feet getting the pack to the total expected sum. Balanced chargers just use the two-conductor cable to monitor the total voltage of the pack as it's being charged.

 

I also have this clever gadget - the Hyperion EOS Sentry battery checker:

 

1000

 

Before and after charging a LiPo pack, I can attach this to the pack's balanced charging connector, to measure the total voltage or the voltage in each cell.  It can also be used while the battery pack is attached to a load, to monitor the voltages as the pack is being discharged, but I have a different solution for that:

 

Programmable audible (mega loud) voltage alarm for LiPo packs

 

The biggest problem with LiPo packs is making sure that you don't drive the voltage below 3.0V per cell (to avoid damaging them.)  To that end, I leave an Integy C23212 Lipo Voltage Checker/Warning Buzzer attached to the balanced charging connector while discharging a pack in use. This thing can be programmed to alarm (very loudly, by the way) when any cell in the pack gets down to your specified voltage (I've set mine for 3.0V, but it defaults to 3.3V).  This thing can easily be heard while wearing closed headphones.  (It's designed to be heard by the pilot of a remote-controlled (RC) airplane, from hundreds of feet away.)  

 

More on this stuff, after I've discussed it with Jan.

 

Mike

 

(By the way, I've never been an "RC" enthusiast - I learned all this stuff abou LiPo batteries while perfecting a method to supply my Meier Stepdance with 15VDC.)  


Edited by zilch0md - 8/26/13 at 9:53pm
post #693 of 2631

Mike:

 

The standard TBI binding posts are 5-way.  As shipped, there is a little plug in the center that you can pull out to get to the banana jacks.  The little suckers are in there pretty tight, and don't obviously look like they come out, so I didn't think the jacks were there; however, Jan told me to just pry them out.  I did, and voila, banana jacks. 

 

The Millenia is apparently pretty sensitive to the connections, so Jan won't use just any binding posts.  The ones on the amp are pretty sturdy, and he's using those on the resistor boxes now as well.
 

post #694 of 2631

As to batteries, Jan told me that the only danger to the amp is over voltage above 27 volts, after which the internal protection will kick in -- fuses will blow.  Exploding batteries are not his problem biggrin.gif.

 

I didn't ask him about LiFePos, but I did look into big laptop Li-Ion charging batteries, and he told me they would probably sound crappy because of the circuitry/design.  They just aren't designed for clean-sounding power, which is too bad, because they are very nicely packaged and come with all of the required connections, are easy to charge and don't take up much space.

post #695 of 2631
Nice seeing all the battery love. I recently toyed with flying RC helicopters and was wondering how to increase flight time and dead weight for a HD camera. My brother does roof restorations and I was thinking of a survey tool to review roofs for storm damage without having to go on the roof. Do the crowns, flashings and valley/downspout conditions, anything seen from the top.
post #696 of 2631
Quote:
Originally Posted by Gary in MD View Post

The standard TBI binding posts are 5-way.  As shipped, there is a little plug in the center that you can pull out to get to the banana jacks. 

 

[snip]

 

That's awesome!  Just looking at pictures, I couldn't tell that they would accept banana plugs.  Excellent!

 

Quote:
Originally Posted by Gary in MD View Post

As to batteries, Jan told me that the only danger to the amp is over voltage above 27 volts, after which the internal protection will kick in -- fuses will blow.  

 

Again, that's great news!   It means I won't have to "pre-discharge" a fully charged "6S" LiPo pack down to 24V from 25.2V, before using it with the MG3.  25.2V is well shy of 27V.

 

Laptop batteries do come with a lot of circuitry that manage their charging and discharge.  The LiPo RC pack I'll be using is primitive - just six cells, in series, with no electronics.

 

Thanks for the feedback!   Valuable info in both posts!  And thanks for all your preceding posts to this thread. I've been contemplating the MG3 ever since SMG52 first wrote about it. Now that you're both chiming in, I couldn't hold out any longer.

 

biggrin.gif

 

By the way, I asked Jan if the resistor box would have to accommodate the fact that my LCD-2 rev.1 presents a 50-Ohm impedance, vs. the 45-Ohm of your LCD-3 (both purely resistive).  He wrote that they are so close it's unnecessary to use different values for the resistors, but he he added that if there were a significant difference in sensitivity, he would have to adjust for that.  I don't believe the LCD-2 and LCD-3 are all that different in terms of sensitivity, so he'll be sending me the same box that you ended up liking the most in your blind comparison.

 

Thanks!

 

Mike

post #697 of 2631
Quote:
Originally Posted by Happy Camper View Post

Nice seeing all the battery love. I recently toyed with flying RC helicopters and was wondering how to increase flight time and dead weight for a HD camera. My brother does roof restorations and I was thinking of a survey tool to review roofs for storm damage without having to go on the roof. Do the crowns, flashings and valley/downspout conditions, anything seen from the top.

 

We're going off-topic, but I have a friend who flies these DJI Phantom quad-copters with a Go Pro Hero3 video camera attached to its belly. 

 

 

 

http://www.popularairsoft.com/news/dji-phantom-quadcopter-w-camera-mount

 

http://www.dji.com/product/phantom/

 

 

I've flown it myself - no experience required. They are a LOT easier to fly than what I've read about flying true RC helicopters.  It has an on-board GPS, a fluxgate compass, an altimeter, an accelerometer, and sense gyros - all supplying information to a processor that essentially flies the craft for you. If you let go of the controls or even turn off the transmitter, it will just stop and hover at its current position, holding that position even against pretty strung gusts of wind.  It can even land automatically, at the position where you first powered it on, if your transmitter goes dead, or the batteries in the quad copter are getting too discharged to continue flying.  It flies to a position about 60 feet above where it took off, then slowly comes down to land.  My friend demonstrated this for me.  Very impressive technology.

 

Toys for big boys.  My friend is on his third DJI Phantom - having destroyed the first two, each after many hours of use, fortunately. (Hint: He now uses Loc-Tite brand semi-permanent thread-locking solution on the propeller nuts!)

 

Mike

post #698 of 2631
Quote:
Originally Posted by zilch0md View Post

 

That's awesome!  Just looking at pictures, I couldn't tell that they would accept banana plugs.  Excellent!

 

 

Again, that's great news!   It means I won't have to "pre-discharge" a fully charged "6S" LiPo pack down to 24V from 25.2V, before using it with the MG3.  25.2V is well shy of 27V.

 

Laptop batteries do come with a lot of circuitry that manage their charging and discharge.  The LiPo RC pack I'll be using is primitive - just six cells, in series, with no electronics.

 

Thanks for the feedback!   Valuable info in both posts!  And thanks for all your preceding posts to this thread. I've been contemplating the MG3 ever since SMG52 first wrote about it. Now that you're both chiming in, I couldn't hold out any longer.

 

biggrin.gif

 

By the way, I asked Jan if the resistor box would have to accommodate the fact that my LCD-2 rev.1 presents a 50-Ohm impedance, vs. the 45-Ohm of your LCD-3 (both purely resistive).  He wrote that they are so close it's unnecessary to use different values for the resistors, but he he added that if there were a significant difference in sensitivity, he would have to adjust for that.  I don't believe the LCD-2 and LCD-3 are all that different in terms of sensitivity, so he'll be sending me the same box that you ended up liking the most in your blind comparison.

 

Thanks!

 

Mike

Wow, sounds like you are well prepared to go the battery route. I realize that many people who have tried it that way seem to prefer the Millenia on battery power, but I decided to stick with the ac, at least for now. I only have one 12 volt battery, one which  Jan recommended I try, so maybe it's because of the 12 volts vs. 24.....but I find I prefer the fuller sound that the ac provides to the more transparent sound of the battery pack. So, only just suggesting trying both ac and battery. Also, interconnects and speaker wire also effect the sound, so if you have some different 'brands' laying around, you could also experiment with those. I simply find the amp to be mucho transparent to what it is fed. 

post #699 of 2631

Drool!

 

Tick, tock, tick, tock...

post #700 of 2631
What Gary said!

Jan Plummer has confirmed Gary's figure for maximum supply voltage for the MG3 at 27.5V. Somewhat counterintuitive to my initial pondering, Jan says the MG3's 4-amp fuse will blow if the MG3 sees more than 27.5 Volts. In other words, the MG3 just can't pull more than 4 Amps when the supply voltage is less than 27.5V.

So, I can't blow the fuse using a 6-cell, 25.2V LiPo battery (never say never). And with a capacity of 3600 mAh (barring any exaggeration of the battery's specs), there's a good chance it will last a minimum of 0.9 hours between charges (even if it were to run full out at 4000 mA continuously - which is not likely.)

:-)
Edited by zilch0md - 8/17/13 at 6:55pm
post #701 of 2631

I just ordered a Millenia, as well.  Its all Gary's fault! blink.gif

 

I was thinking of going the 24 VDC battery route, but then I thought it would be more fun to use a capacitor bank :)

 

When it arrives, I'll do some measurements on the power supply and see how much residual noise is there, then look at building a filter cap box.  

 

 

Good times!  By the way, Gary, thanks for the final installment with the Odyssey review!  Definitely on the acquisition list, but got to pay off some stuff first!

post #702 of 2631
:-)
post #703 of 2631

Folks:

 

I've just done a couple of hours of comparing the Millenia with lithium AAs vs. the AC power, and I think I like the AAs a bit better.  There isn't a huge difference -- it still sounds like the Millenia -- but I like the little bit of extra clarity on the top end that the batteries provide.  Note that this is with 8 AAs, which cost me about $15, and they are pushing 12V vs. 24; however, most headphones probably won't draw enough power to make any audible difference (HE-6s probably would).  While AAs are much cheaper than the LiFePo battery setup, or even the lead-acid setups that some are using (by the time you get done wiring everything up, most folks end up spending over $100) they aren't rechargeable, so won't last long. 

 

Another idea that folks are trying is bench-top linear power supplies.  They can be had for <$100, and while they are ugly suckers, they aren't any uglier than batteries, don't take up much more space and they just stay plugged in, reducing the hassle factor of charging batteries.  I've been researching them and the biggest drawback I've seen with them is that the fans on some of the cheaper ones sound like jet engines (okay, not really, but you get my point).  Not exactly what we want for driving audio equipment. I know that there are some out there that use just heat sinks, and if I can find a decent one for under $125 I might try it. 

post #704 of 2631

I anticipate using AC power much of the time.. but I'll probably get 16 Eneloop (NiMH) batteries and a couple of (4-bay) chargers.. so I can, essentially, run it off batteries continuously.

post #705 of 2631

Flysweep:

 

You shouldn't use eneloops, they are only 1.2V, which isn't enough -- you end up with 1.2 x 8 = only 9.6V.  You need either alkalines or lithiums, as both are 1.5V, to get to the minimum recommended 12V total. 

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