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PostPosted: 06 Feb 2017, 13:01 
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Joined: 27 Aug 2009, 15:19
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Location: Sweden
Just got myself a couple of digital amp modules rated 30W (mono) they are really small in size but with great sound
for me they are perfect to turn passive bookshelf speakers into active ones,
but now i'm kind of stumped , i want a potentiometer at signal in to adjust volume and i wonder what resistance i need,
i have 10K , 20K , 50K , 100K , 250K and 500K all log's also a few in linear ones,
one of the only things i know about these is the chip itself and that is a TPA3110 and input voltage.
Also have 2 pcs of the 60W version.




-Kjell .


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PostPosted: 06 Feb 2017, 13:56 
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Joined: 08 Aug 2009, 03:11
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It depends on the devices input impedance. The the majority of these I see use 20K. But 100K is the "standard" and won't hurt anything. If the device's impedance is low, it'll just mess up the taper.

Cheers!

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* Ratings are for transistors - tubes have guidelines*
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PostPosted: 06 Feb 2017, 13:58 
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Then i try 100K and see what's happens .
Thank's Geek.


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PostPosted: 06 Feb 2017, 14:00 
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Joined: 28 May 2008, 21:53
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Hi, can you share a link to the boards, they look interesting. The larger ones as well. They look neat for active speakers as you noted.

My experience with these sorts of boards are that the ratings are peak power, so actual (RMS) power output will be closer to half or 15W and efficiency is about 85% to 90%.

Probably 50k or under. I'd bet the 20k would be a good match.

Let us know how you make out.

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PostPosted: 06 Feb 2017, 14:07 
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Hi Gio, here is the link's for the modules i got
http://www.ebay.co.uk/itm/301984281646
http://www.ebay.co.uk/itm/291791350601
i really love these small modules , they are cheap , sounds great , take very little power and almost no heat ,
Pricewise , for what i payed for 1 pcs 30W module i couldn't even buy the 4 smd e-caps here in sweden ....


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PostPosted: 06 Feb 2017, 17:39 
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Hi,

I just downloaded the datasheet for the chip. The input imedance changes with the gain! So without knowing what the gain is set at, use the lowest pot you can.... 20K at most and it looks like 10K might be in order here.

*edit*

Too big to upload here. Datasheet on my site:
http://geek.scorpiorising.ca/files/tpa3130d2.pdf

_________________
-= Gregg =-
* Ratings are for transistors - tubes have guidelines*
Home: GeeK ZonE
Work: Classic Valve Design


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PostPosted: 06 Feb 2017, 17:49 
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Hi Geek,
10 or 20K it is then so i will try that, thank you for the datasheet,


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PostPosted: 06 Feb 2017, 19:27 
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The datasheet notes efficiency >90%. Were you planning on using a heatsink?

I'm curious what the heatsink options would be? Maybe just a small one that affixes with a sticker.

Cheers

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PostPosted: 06 Feb 2017, 19:33 
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I also wondering about heatsink on these guy's , it is really no room for a heatsink on top of the chip but backside is
totally flat and just very small holes underneath the chip,
maybe use a thicker self adheisive silicon pad and stick heatsink to module .


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PostPosted: 06 Feb 2017, 21:56 
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Page 31 of the datasheet shows a recommended heatsink. Digikey ATS2177-ND is the unit.

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* Ratings are for transistors - tubes have guidelines*
Home: GeeK ZonE
Work: Classic Valve Design


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