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-   -   Sure TPA3122 build (http://www.diyaudio.com/forums/class-d/224705-sure-tpa3122-build.html)

prezden 1st December 2012 01:13 AM

Sure TPA3122 build
 
I have just finished putting together a Sure TPA3122 kit. It is working well. Sounds a little thin though. Any one have any thoughts on modifying it to get a bit more body, especially bass out of it. I am planning on using it in a small portable with a pair of Tan-Ban 3" full range drivers and a 12 l-ion battery pack.

Thanks in advance for your thoughts :)

prezden 1st December 2012 01:41 AM

2 Attachment(s)
I forgot the photo of the board and specs from Sure

theAnonymous1 1st December 2012 12:19 PM

Sorry to say, but those tiny inefficient drivers are going to need all the power they can get. You would have been much better off going with an amplifier with bridged outputs.

prezden 2nd December 2012 07:46 AM

I'm not expecting miracles out of the drivers or the amp. I'm realistic enough to know you can only get so much out a $10 amp and $16 speakers. I would like to get the best our of them as is possible and hopefully learn something along the way. Any suggestions would be greatly appreciated. :o

prezden 4th December 2012 09:35 AM

No suggestions :confused:.
I'm going to start my second one and would like to try and improve it but don't have the know how or experience to know what mods will give the best result. I worked through the modifications recommended for the Sure 2024 and the improvements were very noticeable. I was hoping to do something similar with this one.

cheers

LBHajdu 6th December 2012 04:09 PM

In terms of minor things you can try. You could increase the value of the input caps (the datasheet at Texas Instruments shows 1.0uF). You could also see what the max rail voltage is with your load and see if there is head room there, just be careful not to blow it.

The datasheet shows this amp will run with in BTL (Bridge Tied Load) and since you’re building another one that might just be the ticket. That will allow you to get rid of the output DC blocking caps but you will need a balanced input source. It also doubles the power.

The datasheet should give you some ideas and tell you what the limits are. I swap in and out of my system a class-d chip amp (5th-Order Delta-Sigma) running on a 12v supply. With my Fostex 6” 93dB\W speakers it sounds fine. I lower the damping by placing some 8ohm power resistors in series with the speaker. I can afford to waste 50% of the power because my speakers are efficient. I still think SE tubes still produce a better balance, but not having to worry about power consumption and leaving the class-d amp on all the time is truly a guiltless pleasure.

Leve

hoxuanduc 6th December 2012 11:32 PM

I would double or quadruple c7, c8, c10, c11. I think the caps form high pass filter @ around 100Hz. This may explain bass roll off.

Duc

prezden 7th December 2012 06:04 AM

Thanks guys
I don't understand what's happening with c1 @ 2. There is a box around them with unused connector holes. Is this for an alternative larger cap? I couldn't find anything in the specs. I'm afraid I don't understand most of what I read yet.

Budgie 8th December 2012 04:20 PM

Your right, the extra holes are for a larger size input capacitor (at C1 and C2) and adding a 1 film cap in those holes is a good idea. You can leave the one that's all ready on the board in place.

The biggest problem is the output coupling capacitors, as duc mentioned. The schematic shows two 220 mfd paralleled. That's too small to provide good bass to a 4 or 8 ohm speaker. The TI data sheet for this chip suggests 1000 mfd for a 20hz cut off with 8 ohm speakers and 2200 mfd for 20hz with a 4 ohm speaker for the output coupling cap.

prezden 8th December 2012 05:46 PM

Thanks Budgie
What would be a good size input cap for C1 and C2


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