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studio45 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote studio45 Quote  Post ReplyReply Direct Link To This Post Posted: 30 January 2017 at 3:45pm
You will need some airflow for the amp. I guess you are worried about water ingress - there's 2 things to remember there: 
a) this is all low-voltage stuff, so the potential for sudden catastrophic failure is much less than with 230v AC flying about. The official acronym for <50v DC supplies is "SELV" for "Safe Extra Low Voltage". If you dropped your amp board in the canal while it was powered on, it would have a pretty good chance of survival, if you fished out out promptly. And you're never going to get a shock from voltage this low.
b) How often are you really going to be playing out in the pouring rain without any cover? Not that often....12v systems are for when it's sunny ;)

So you can cut some vents in the Tupperware without worrying. In my experience Sure amps run incredibly cool, and that fan will hardly ever come on. (Unless yours is one of the boards where it runs all the time, in which case you'll probably never see it run full speed.)

Have you considered using a switchmode boost regulator at all? EG the Sure "boost regulator power supply" boards? Not necessarily to raise the voltage above 30v (although that might be beneficial) but for the other thing they do - hold their output voltage constant as the batteries on the input discharge. This, combined with good battery protection, means you will get 100% full power right down to the "flat" state, rather than a gradual loss of headroom as the rail droops. At the cost, of course, of a couple of % wasted power in the regulator itself.
Studio45 - Box Builder Commotion Soundsystem -Mobile PA
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slaz View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote slaz Quote  Post ReplyReply Direct Link To This Post Posted: 30 January 2017 at 3:48pm
Originally posted by ambientvoid ambientvoid wrote:


The amp module is the tk2050 2 x 100w.


Erk .... whats the highest supply voltage rating for that amp ? I thought it was about 30V ?
If using 2 x series 4s LiPo batts, your gonna have close to 34V at full charde of 4.2V/cell (or nearly 33V at 4.1V/cell). I'd have gone for the Sure 5630 module ....


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Post Options Post Options   Thanks (0) Thanks(0)   Quote ambientvoid Quote  Post ReplyReply Direct Link To This Post Posted: 30 January 2017 at 4:37pm
Originally posted by studio45 studio45 wrote:

How often are you really going to be playing out in the pouring rain without any cover? Not that often....12v systems are for when it's sunny ;)

So you can cut some vents in the Tupperware without worrying. In my experience Sure amps run incredibly cool, and that fan will hardly ever come on. (Unless yours is one of the boards where it runs all the time, in which case you'll probably never see it run full speed.)

just had a thought, could i mount the amp board upside down in a tupperware box vented on the bottom with a gap underneath? that way it should further reduce the chance of water ingress if i am caught out in rain...

Originally posted by studio45 studio45 wrote:

Erk .... whats the highest supply voltage rating for that amp ? I thought it was about 30V ?
If using 2 x series 4s LiPo batts, your gonna have close to 34V at full charde of 4.2V/cell (or nearly 33V at 4.1V/cell). I'd have gone for the Sure 5630 module ....
it is 30V max. im a bit confused now because it says 14.8V on the side of each battery so surely that would be 29.6V for 2 batteries?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ambientvoid Quote  Post ReplyReply Direct Link To This Post Posted: 30 January 2017 at 6:36pm
ok so apparently the voltage on the battery is nominal voltage (why they can't put the max safe voltage i don't know...), so would it be safe to combine a 3s battery in series with one of my 4s batteries to make 7s and therefore 29.4V?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote slaz Quote  Post ReplyReply Direct Link To This Post Posted: 31 January 2017 at 2:57pm
Well you _could_ change one of the 4S packs for a 3S one - if the cell capacity is the same ....

BUT - you _might_ be OK using the 2 x 4S packs - especially if you charge to 4.1V/cell rather than 4.2V/cell - would be less than a volt over 32V - and this voltage would drop very quickly to below 32V.
I think I'd be inclined to risk it.

Thing about these chip-amps is - often they just paste in the chip specs as if they were the specs of the assembled module, when in fact other factors can come into it. One thing to check, for instance, is the voltage rating of the capacitors on the board. For a 2050 board, some of the cheapest boards will use 35V caps- i.e. _just about_ in spec, but too close for comfort really. Hopefully the Sure ones might use 50V or 63V caps.

Fairly sure I've seen - somewhere - specs of 2050 chip as max Vcc of 36V .....


Edited by slaz - 31 January 2017 at 2:59pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ambientvoid Quote  Post ReplyReply Direct Link To This Post Posted: 31 January 2017 at 3:39pm
i just checked and the 6 big caps down the sides are 63V, there are 5 smaller caps on the front of the board near the inputs that are rated as 25v though so i don't know if that makes a difference...

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Post Options Post Options   Thanks (0) Thanks(0)   Quote slaz Quote  Post ReplyReply Direct Link To This Post Posted: 31 January 2017 at 4:11pm
OK well you won't have a problem with the smoothing caps (the 6 big ones) and any others won't be across the main power supply rails.

As you're only using one channel of that amp, and its loaded with 8R, you'll be using only about 30% of its capacity - so shouldn't be any thermal problems.

I reckon you'll be OK with 2 x 4S packs .... (but don't blame me guv :-) )


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Post Options Post Options   Thanks (0) Thanks(0)   Quote ambientvoid Quote  Post ReplyReply Direct Link To This Post Posted: 31 January 2017 at 4:37pm
what sort of impact would it have if i put a couple of 40w 4ohm speakers on the other channel?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote slaz Quote  Post ReplyReply Direct Link To This Post Posted: 31 January 2017 at 5:32pm
Originally posted by ambientvoid ambientvoid wrote:

what sort of impact would it have if i put a couple of 40w 4ohm speakers on the other channel?


Well don't put em in parallel - series will be 8R load so OK. It'll nearly double your power consumption, so obviously it'll shorten the battery run-time.

Depending on what kind of speakers, where/how you mount/use them - well it might sound OK I suppose, but it could well also wind up sounding "messy" ....

I'd fit an extra o/p socket for the spare channel - so if you get/borrow/hire another Titan 12 you can ramp it up a bit.


Edited by slaz - 31 January 2017 at 5:37pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ambientvoid Quote  Post ReplyReply Direct Link To This Post Posted: 31 January 2017 at 6:16pm
right probably won't do that then, mostly just wondering as iv got a couple of 6.5" marine speakers spare now and i'll have at least a foot or so of empty space forward of the rear facing Titan 12...

i like the idea of mounting a spare socket, one idea i had was to make something like a luggage rack for the front half of the trailer so that could be ideal for strapping a spare speaker to when im not carrying a picnic basket or something haha. LOL
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Post Options Post Options   Thanks (0) Thanks(0)   Quote slaz Quote  Post ReplyReply Direct Link To This Post Posted: 31 January 2017 at 8:22pm
Originally posted by ambientvoid ambientvoid wrote:


 i'll have at least a foot or so of empty space forward of the rear facing Titan 12...


Sounds like enough space for a good few beers :-)
The marine speakers will likely be pretty low efficiency - ain't gonna do much for your sound.
Use em for another box/project.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote ambientvoid Quote  Post ReplyReply Direct Link To This Post Posted: 01 February 2017 at 9:16am
i had another look at the sure tk2050 user manual link on parts express (weirdly i didn't get a paper copy with my amp) to double check the max voltage and it seems to list two maximum voltages, in the Electrical Characteristics section it says the max input voltage is 30V but in the Overview section it says it can be powered by "any DC power supply ranging from +10 to 36V, which can be used to drive any 4ohm or 8ohm passive speakers". so that's confusing...
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