mini-amp

[keith_correa]

Something to share: Some months ago, on a whim, I bought this amp board from e-bay based on the TDA7297. If I remember right, it outputs 15Wx2 and needs 15VDC. I remember paying US$6/- for it with free shipping

I had tucked it away and today while searching for something, I found it in the envelope it came in. Hunted around for a 12V wall wart and found that my set-top box uses a horribly cheap looking 12VDC wall wart PS.

I connected the board to this horrible PS, to my bedroom mini-component bookshelf speakers and fed it tunes from i-Pod. Dynamic, detailed and amazingly lush sound. This amp smokes the Tripath 2020 amps that I have heard. It's a super bargain. I did not have to turn the volume more than 10 o'clock for room filling sound. The only issue that I found is that it has a slight hum but I'm sure that can be easily fixed with a little bit of investigation.

Imagine what it will do with a better PS and better caps.

There are 2 electrolytic caps, 2 ceramic caps, 1 LED, 3 resistors and of course the TDA7297 on the board.

Searching for TDA7297 throws up this photo which is exactly what I got.

 

[hemantwaghe]

Please can u provide any current link?? Also any cheap version with remote!?

 

[kapvin]

Something to share: Some months ago, on a whim, I bought this amp board from e-bay based on the TDA7297. If I remember right, it outputs 15Wx2 and needs 15VDC. I remember paying US$6/- for it with free shipping

I had tucked it away and today while searching for something, I found it in the envelope it came in. Hunted around for a 12V wall wart and found that my set-top box uses a horribly cheap looking 12VDC wall wart PS.

I connected the board to this horrible PS, to my bedroom mini-component bookshelf speakers and fed it tunes from i-Pod. Dynamic, detailed and amazingly lush sound. This amp smokes the Tripath 2020 amps that I have heard. It's a super bargain. I did not have to turn the volume more than 10 o'clock for room filling sound. The only issue that I found is that it has a slight hum but I'm sure that can be easily fixed with a little bit of investigation.

Imagine what it will do with a better PS and better caps.

There are 2 electrolytic caps, 2 ceramic caps, 1 LED, 3 resistors and of course the TDA7297 on the board.

Searching for TDA7297 throws up this photo which is exactly what I got.

it's always great to hear about such heroic little over achievers. and the price even in these dollar deprivation times, is affordable.

I look forward to your experimentations. Maybe we could get a group buy going.

 

[keith_correa]

Please can u provide any current link??

I checked my e-bay purchase history and went to the sellers e-bay store. His store is empty :sad:

Googling, I found the board here.

Also any cheap version with remote!?

Cheaper than US$6? I think that's something even the Chinese will not be able to pull off hyeah:

 

[keith_correa]

Searching for TDA7297 throws up quite a few results on e-bay. I like this & this. They are not assembled boards but they claim to provide WIMA caps [assuming that they are not fakes].

 

[keith_correa]

Need help/advice:

Here is the datasheet

The input caps are 0.22uF ceramic types and the value is as per the datasheet. I was thinking of paralleling 0.12uF poly caps to these. Or maybe replace these with 0.10uF Ceramic + 0.12uf Poly. Or... Need suggestions here.

I think the 2 electrolytics [2200uF & 10uF] are not in the signal path so I don't think replacing them is going to cause a sonic benefit. Please correct me if I'm wrong.

Power supply. This probably may [will?] make the biggest difference of all. I'm inclined not to spend too much and just buy [or salvage from friends] a 15VDC laptop supply. If I go this route, what can I do to minimize SMPS noise. I heard that motor run caps after the SMPS make a difference - they say:to shunt the noise from the +ve to the _ve terminal and hence go to ground. Of course the best route to go would be a linear regulated PS but that would probably cost 4 times the cost of the board.

Replace the 100K pot with a better quality pot. Or maybe I'll just leave the pot alone.

Please feel free to criticize or/and advise.

 

[sashijoseph]

The datasheet figures don't look too good and seem representative of the application area suggested for this chip: "designed for television and portable radio applications".

For eg the THD+N figures compared with a LM3875 look pale.
At 10W into 8ohms and 1kHz the spec reads 0.3% THD,which for a LM3875 would be ~0.006% amd for a LM3886 ~0.003% and nearabouts for a TDA7294.

Similarly the PSRR figures are 56dB versus 120dB of the 3875,implying a well regulated linear supply or a good quality smps be used.

Also,the frequency response is shown to roll off a bit too early,at the low end.

Well that's what an honest datasheet says,but like the signature of a FM reads
"We should no more let numbers define audio quality than we would let chemical analysis be the arbiter of fine wines..." -- Nelson Pass
Sp,if the ears are pleased and the pockets happy,the datasheet be damned.

As for improvements to the board replace those ceramics with good quality polypropylenes(metallised or film/foil) or even polyesters.If space permits you may use a bigger value like 1uF or so.

 

[keith_correa]

Sp,if the ears are pleased and the pockets happy,the datasheet be damned.

The ears ARE pleased for the RIDICULOUSLY low price I paid. It has no right to sound so good for that price. Yes, to hell with the datasheet

As for improvements to the board replace those ceramics with good quality polypropylenes(metallised or film/foil) or even polyesters.If space permits you may use a bigger value like 1uF or so.

Thanks! Does anyone know where I can find 1uF polypropylene/polycarbonate caps at Lamington road? Also if anyone has any of these to spare, I'll buy 2 if you will sell.


Also, do those electrolytics need to be replaced?

 

[linuxguru]

Does anyone know where I can find 1uF polypropylene/polycarbonate caps at Lamington road? Also if anyone has any of these to spare, I'll buy 2 if you will sell.

Also, do those electrolytics need to be replaced?

It's unlikely that any 1uF polypropylene or polycarbonate will fit in the limited space on that board. Your best bets are MKT-type box-type polyesters in 5 mm pitch, like the Wima MKS2-XL, which is available in 5 mm pitch from 1 uF to 3.3 uF. These can directly replace small electrolytics.

The large electrolytics may be replaced by better ones like Panasonic FC/FM/NHG or Nichicon FG/FW/KG/KW/HD or Rubycon ZL/ZLH or Elna RE3/RJ3/RJ4/RJH/RJJ.

 

[keith_correa]

It's unlikely that any 1uF polypropylene or polycarbonate will fit in the limited space on that board. Your best bets are MKT-type box-type polyesters in 5 mm pitch, like the Wima MKS2-XL, which is available in 5 mm pitch from 1 uF to 3.3 uF. These can directly replace small electrolytics.

The large electrolytics may be replaced by better ones like Panasonic FC/FM/NHG or Nichicon FG/FW/KG/KW/HD or Rubycon ZL/ZLH or Elna RE3/RJ3/RJ4/RJH/RJJ.

Hi Siva, I'm looking to replace the input ceramic caps and given the space available, nothing will fit including the box caps. I'll have to fit replacements under the board. Considering this, what do you feel are worthy replacements given that the assembled board is just ~Rs.400.

Do you think the 2 electrolytics are worth replacing and will/may contribute +vely to the sonics?

 

[keith_correa]

Found some here. So which among these should I choose to replace the two 0.22uF ceramic caps?

And if replacing the electrolytics will make a +ve difference, I guess I could try from these. Also the datasheet shows these cap values to be 470uF & 0.1uF. The ones on the board are much larger: 2200uF & 10uF.

 

[linuxguru]

So which among these should I choose to replace the two 0.22uF ceramic caps?

Also the datasheet shows these cap values to be 470uF & 0.1uF. The ones on the board are much larger: 2200uF & 10uF.

The ceramics may be replaced by Wima MKS02 in 2.5 mm pitch through-hole, which is available in values in the range of 0.1 to 0.33 uF. Even better is Wima MKI2 0.15 uF, but it's 5 mm pitch and nearly unobtainium now. Wima MKP2 is also available in 0.15 uF, 5 mm, but it's a moderately fat and tall box cap that may not fit - available from EBay seller electricslee in Taiwan, who has a great selection of hard-to-find Wima caps - though not exactly cheap, given the quality of Wima they're still good value.

Another alternative is to use a Panasonic ECHU 0.1uF/16V stacked PPS film SMD cap on the underside of the board - if there's space, you can use two in parallel to get 0.2 uF. That's the best small-sized cap available, as well as the smallest good film cap available - it's 1206-size SMD, and rivals Rubycon Black Gate PK in sonics at a fraction of the price. The only catch is that it's easily damaged by overheating during soldering.

Larger electrolytics should have numerous options for the given value and size, and can be replaced at leisure. Elna RE3, Panasonic FM/FJ are very compact for any given capacitance value and voltage rating.

 

[sashijoseph]

Found some here. So which among these should I choose to replace the two 0.22uF ceramic caps?

And if replacing the electrolytics will make a +ve difference, I guess I could try from these. Also the datasheet shows these cap values to be 470uF & 0.1uF. The ones on the board are much larger: 2200uF & 10uF.

Siva's suggestions are unbeatable,but if you plan to buy from the site you linked,kindly skip the VC ones...which leaves you with only the no-name 1uF's.

So you may try your luck with them..who knows

 

[kaushik]

good find.. but there are many ready chinese amps with 12v for 15USD
can be put into duty with a smps/adapter
however,
taking a kit like this and putting casing is good time killler

 

[keith_correa]

good find.. but there are many ready chinese amps with 12v for 15USD can be put into duty with a smps/adapter however,
taking a kit like this and putting casing is good time killler

It was not a kit but came fully assembled. Like you said, of course there are many assembled amp boards available but none that I found for US$7 except this. US$15 is pricey compared to the price of this little wonder

 

[vivek.saikia]

Good candidate for making a DIY portable (bluetooth) speaker....
Just put two fullrangers in both ends of a PVC pipe.....put this amp and a bluetooth receiver....and you have a portable speaker!! Only problem is the battery as this thing needs higher voltages.

 

[suraj]

bump!
came across this,searching to replace a blown tape deck's amp for cheap.

Mini MKLL TA2024 Tested PCB Power Digital Audio Amp Amplifier Board 12V 2X15W | eBay

Beavis hifi says it should be OK,and i have the necessary mod parts already.
Anyone has any experience with this?