Ah, thanks.
Don't worry I'll be fiddling with more expensive amplifiers. However preliminary tests with say the 7293 show that in order to get the same quality it requires a battery to power part of a feedback network. What I mean is it's actually very difficult to get the quality of the 7297.
The specs for the 7297 that are not good, distortion figures above 10w begin to climb, and the PSRR isn't so great. However the PSRR is addressed in my unit by many things, making it a non-concern really. The distortion doesn't appears to have an affect on sound. But when the amp is pushed hard you'll lose some information and it gets a "busy" sound. To do that to a point where you feel like you're losing much, with my 87db speakers at 8ohm, it's pretty loud and uncomfortable.
I chose it specifically by listening to it. The active (chip) has qualities so many other things simply do not at a similar price or very far beyond. But the initial Chinese version, while showing a lot or promising sound, also had huge drawbacks in quality that had to be overcome. It wasn't till the addition of the capacitor multiplier that it really became something serious. And by serious I mean competitor with amps in the $5k+ range (commercial).
I have just completed a trio of lunch box kits 
These 7297's are best ones I have found so far. Digital Audio Amplifier Board TDA7297 2 15W Dual Channel AC DC 12V Version B W5 | eBay
The speakers are Eastech made for Sony that I got at a thrift store. Fun little project. For a $20 stereo they are amazing. I would venture to say they are the best sounding stereo of this size I have ever heard. My daughter says they sound better than her Bose system.
These 7297's are best ones I have found so far. Digital Audio Amplifier Board TDA7297 2 15W Dual Channel AC DC 12V Version B W5 | eBay
The speakers are Eastech made for Sony that I got at a thrift store. Fun little project. For a $20 stereo they are amazing. I would venture to say they are the best sounding stereo of this size I have ever heard. My daughter says they sound better than her Bose system.
Attachments
Battery, regulator or CCS is not actually required for the 7293.
What it has to offer is two fold (by comparison), in that is is not bridged and therefore hasn't automatically halved the quality, and that it does have greater power and therefore is less likely to clip.
I'd also venture to say that any configuration that is totally stable (and has therefore avoided that unfortunate datasheet schematic) also does have a more pleasant tonality, which is one less thing to worry about. It is not typical to have avoided the bad schematic; however, if one has done so, then the chip could be rewarding and quickly so. I don't suppose that you'd have any trouble on that first and most important step.
Also, it is not more expensive for the $2 chip; but, the power source is certainly more expensive, and more powerful.
If I were asked which is better, I'd have to say that the 7293 could do a passable and mundane job at your television but is likely to do far better on music replay tasks. Just bear in mind the application and venue size as well.
Sorry Daniel but that's a very assumptive outlook based on best wishes.
The 7293 in stock form isn't nearly as refined as the 7297 in my configuration. But with a special feedback system that absolutely has to run on batteries until further noted, it's about the same. Believe me I want it off of batteries but it's not showing to be possible yet.
The 7297 isn't bridged and cannot be under any circumstances. It's balanced, which is often considered a step up, not down.
You let me know when someone prefers a 7293 configuration over two Pass amplifiers, then I'll believe your put down of the 7297. Please check out the Audiocircle page if you want some verification on what people think about it.
BTW the first speakers I could drive decently at moderate volumes with the 7297 was a pair of planar-magnet hybrid speakers. Whatever clipping occurs at some crest moments is rather inconsequential to the listener. But if you try to drive it beyond it's means it'll sound a little bit "busy" but still very pleasant. For off-axis (wondering about while music plays) clipping would be a mystery, but if you're infront of them and crank it it might sound busy with sub 90db speakers or ear blistering levels you can't understand anyway. Perhaps one of the reasons it gets away with this so easily is the balanced output and a lack of oscillations that sink power, but aren't uncommon among many amplifiers. (hence why some companies sell uber expensive cables with zobels in them)
The 7293 in stock form isn't nearly as refined as the 7297 in my configuration. But with a special feedback system that absolutely has to run on batteries until further noted, it's about the same. Believe me I want it off of batteries but it's not showing to be possible yet.
The 7297 isn't bridged and cannot be under any circumstances. It's balanced, which is often considered a step up, not down.
You let me know when someone prefers a 7293 configuration over two Pass amplifiers, then I'll believe your put down of the 7297. Please check out the Audiocircle page if you want some verification on what people think about it.
BTW the first speakers I could drive decently at moderate volumes with the 7297 was a pair of planar-magnet hybrid speakers. Whatever clipping occurs at some crest moments is rather inconsequential to the listener. But if you try to drive it beyond it's means it'll sound a little bit "busy" but still very pleasant. For off-axis (wondering about while music plays) clipping would be a mystery, but if you're infront of them and crank it it might sound busy with sub 90db speakers or ear blistering levels you can't understand anyway. Perhaps one of the reasons it gets away with this so easily is the balanced output and a lack of oscillations that sink power, but aren't uncommon among many amplifiers. (hence why some companies sell uber expensive cables with zobels in them)
DIY TDA7297 amplifier module
I have four of those amplifiers and am listening to them in different applications. They were under 3 dollars... two of them came with button volume control and others with the better potentiometers. I ended up replacing the button volume controls with real potentiometers, as the button ones were flimsy, intermittent and short lived(!). I added 0.2uf capacitors in parallel to the input capacitors of all four amps and added 2000 uf and 0.1 uf as power supply filter capacitors on all four amps. They sounded well.... but after modification they sound just great. I use them with BIC Ventury and with JBL Loft40 speakers.... After modifications the low frequency end is more robust and clean and the high end seem to be cleaner.
Only problem with these amps is the challenge in finding inexpensive enclosures for the amps, that would fit. It would be a bit odd to have a 3 dollar amp housed in a 50 dollar case......Any enclosure advise from anyone on this forum (I would not modify The speaker enclosures to host the amp... That may effect their tuning.
I have four of those amplifiers and am listening to them in different applications. They were under 3 dollars... two of them came with button volume control and others with the better potentiometers. I ended up replacing the button volume controls with real potentiometers, as the button ones were flimsy, intermittent and short lived(!). I added 0.2uf capacitors in parallel to the input capacitors of all four amps and added 2000 uf and 0.1 uf as power supply filter capacitors on all four amps. They sounded well.... but after modification they sound just great. I use them with BIC Ventury and with JBL Loft40 speakers.... After modifications the low frequency end is more robust and clean and the high end seem to be cleaner.
Only problem with these amps is the challenge in finding inexpensive enclosures for the amps, that would fit. It would be a bit odd to have a 3 dollar amp housed in a 50 dollar case......Any enclosure advise from anyone on this forum (I would not modify The speaker enclosures to host the amp... That may effect their tuning.
All kinds of ready-made (found?) enclosures are possible. Keep in mind that if you are to use fully "sealed" enclosure (no air vents), check the heatsink temperature first. Excessive heating shouldn't be a problem if you're using it powered by 12V... But, check the heatsink first
If you check this thread, you'll see that people use all kinds of enclosures (wooden tea cases, etc.), so anything can be used with a little ingenuity.
If you have access to simple tools, even more "luxurious" cases are possible.
Thanks for tips on your mods. These have been powering background kitchen speakers so never bothered to mod them. They sound quite decent stock but adding some caps sounds easy so I may try.
Check out magnetic lid chocolate boxes. The cardboard is stiff enough to take a banana binding post output and 3.5mm jack or RCA feedthrough jacks. The lid has magnetic snap for quick access if needed. If 12v don't worry about heat but if 19v watch out - smoking hot. I tried running at 19v for a few days - works and can get louder but not sure if good for longevity of amp and heatsink would need to be increased.
Cheap case for cheap Lunch Amp
Here’s my solution: a cut and emptied Ikea Lack shelf ( 4 € ).
It’s not new to me: please see here ( http://www.diyaudio.com/forums/chip-amps/275869-ikea-gainclone.html ) and here ( http://www.diyaudio.com/forums/class-d/220995-densenclone.html ).
As You can see there’s enough room for dual mono solution, if you like. That’s why the power supply has two outputs …
Ciao.
Luca
Here’s my solution: a cut and emptied Ikea Lack shelf ( 4 € ).
It’s not new to me: please see here ( http://www.diyaudio.com/forums/chip-amps/275869-ikea-gainclone.html ) and here ( http://www.diyaudio.com/forums/class-d/220995-densenclone.html ).
As You can see there’s enough room for dual mono solution, if you like. That’s why the power supply has two outputs …
Ciao.
Luca
Attachments
Here ya go. Mod as you build! Add yer own heat sink..
1set TDA7297 amplifier board spare parts dc 12v grade 2.0 dual audio encoding 15w electronic diy kit-in Integrated Circuits from Electronic Components & Supplies on Aliexpress.com | Alibaba Group
1set TDA7297 amplifier board spare parts dc 12v grade 2.0 dual audio encoding 15w electronic diy kit-in Integrated Circuits from Electronic Components & Supplies on Aliexpress.com | Alibaba Group
Besides psychological, is there any aural difference between your whopping great PS and just a 12v 4 amp brick when one considers the 7297 only puts out a few clean watts?
Sorry, I see the PS is not driving a lunch money amp.
Last edited:
Lunch Money AMP Power Supply
Hi All,
I was shopping on AliExpress and came across this adjustable power supply that claims to go from 15V to 24V with approximately 90 Watts. I want to pick one up for my TDA7297 that i'm modding right now and thought others might have a need for this.
Regards,
Webber
Universal 96W AC Power supply 15V 16V 18V 19V 20V 24V Charger For HP IBM COMPAQ DELL and SONY Notebook Laptop PC -in AC/DC Adapters from Electrical Equipment & Supplies on Aliexpress.com | Alibaba Group
Hi All,
I was shopping on AliExpress and came across this adjustable power supply that claims to go from 15V to 24V with approximately 90 Watts. I want to pick one up for my TDA7297 that i'm modding right now and thought others might have a need for this.
Regards,
Webber
Universal 96W AC Power supply 15V 16V 18V 19V 20V 24V Charger For HP IBM COMPAQ DELL and SONY Notebook Laptop PC -in AC/DC Adapters from Electrical Equipment & Supplies on Aliexpress.com | Alibaba Group
It does: kindly look at my post n. 808, you'll recognise it in 4th picture.
I tried it with different power supplies, and I didn't note particular differences ( note: I don't consider myself as an Audiophile, my ears are not so trained ... ).
So go on with yours: if it sounds good to you, enjoy it. It's useless to look for further improvements.
Ciao.
Luca
Perhaps do not exceed 15v. I read everywhere that the chips that come with the Chinese boards cannot take much more. I happily run mine on a linear lab supply at 13.8v. If you can find a used one locally, that'll be a good bet (also for SQ). I only paid between 15-20 euro for mine.
Mono Conversion for Lunch Money Amp
How many of you want to use these inexpensive amps to drive a single mono kitchen or table radio speaker from a stereo source? Especially nowadays, Windows does not even have a way to play mono from system settings anymore.
I have a mono speaker I use in my office (a flat wall-mounted Alpair 7.3 MLTL) and sometimes I want to use a single Tabaq. But my sources don't make it easy to play mono from stereo sources.
I got this tip from Sreten and tried it out and it works like gangbusters with the TDA7297 or any other class AB amp that can have common ground on both channels. Won't work with class D BTL amps.
Basically connect a 4.7k resistor in series between left and right inputs and common them together. The on outputs use a power resistor like 0.33R in series and tie those together for the singular mono output +ve. Tie the negative speaker outputs together.
I only had 2k resistors and 2R power resistors on hand so did it with those values and it works very well still.
I took an xacto and cut the traces on the PCB between the 3.4mm input jack and pot. Then replaced the cut trace with the 2k resistor for each side. Then connected the resistors together at the stereo pot input. I found that a 10 watt Xircon wirewound sandcast power resistor slips perfectly into the space between the TDA7297 and the heatsink, a few dabs of hot melt glue to hold in place and connect the bottom leads of the resistors to the +ve outs. Tie a common wire between the negatives on the speaker outs. Now connect your speaker to the negative screw terminal for negative and the common outputs of the power resistors for the positive. I used a small alligator clip since this connection no longer has a screw terminal.
Photo of 2k resistors and PCB surgery (reversible if you bridge cut later):
Photo of 2R power resistors with common alligator clip out:
Here it is being tested with Tabaq with P830986:
I tested it by panning the stereo input and found no change in speaker out sound. I also tested by switching between mono and stereo out from my phone. No effect on sound.
Works quite well and a cheap mod for a nice kitchen speaker amp. In normal operation at 12v and with 4ohm speaker, the heatsinks and resistors are hardly warm so hot melt glue is still holding. If not, use high temp RTV.
How many of you want to use these inexpensive amps to drive a single mono kitchen or table radio speaker from a stereo source? Especially nowadays, Windows does not even have a way to play mono from system settings anymore.
I have a mono speaker I use in my office (a flat wall-mounted Alpair 7.3 MLTL) and sometimes I want to use a single Tabaq. But my sources don't make it easy to play mono from stereo sources.
I got this tip from Sreten and tried it out and it works like gangbusters with the TDA7297 or any other class AB amp that can have common ground on both channels. Won't work with class D BTL amps.
Basically connect a 4.7k resistor in series between left and right inputs and common them together. The on outputs use a power resistor like 0.33R in series and tie those together for the singular mono output +ve. Tie the negative speaker outputs together.
I only had 2k resistors and 2R power resistors on hand so did it with those values and it works very well still.
I took an xacto and cut the traces on the PCB between the 3.4mm input jack and pot. Then replaced the cut trace with the 2k resistor for each side. Then connected the resistors together at the stereo pot input. I found that a 10 watt Xircon wirewound sandcast power resistor slips perfectly into the space between the TDA7297 and the heatsink, a few dabs of hot melt glue to hold in place and connect the bottom leads of the resistors to the +ve outs. Tie a common wire between the negatives on the speaker outs. Now connect your speaker to the negative screw terminal for negative and the common outputs of the power resistors for the positive. I used a small alligator clip since this connection no longer has a screw terminal.
Photo of 2k resistors and PCB surgery (reversible if you bridge cut later):
Photo of 2R power resistors with common alligator clip out:
Here it is being tested with Tabaq with P830986:
I tested it by panning the stereo input and found no change in speaker out sound. I also tested by switching between mono and stereo out from my phone. No effect on sound.
Works quite well and a cheap mod for a nice kitchen speaker amp. In normal operation at 12v and with 4ohm speaker, the heatsinks and resistors are hardly warm so hot melt glue is still holding. If not, use high temp RTV.
Attachments
Last edited:
You can also connect the R & L input together after the pot. And then just connect the + and the - for each channel to binding posts. It does work. However it may degrade sound slightly; not that in this application you'd care.
Whatever reason for connecting the + output together for resistors is silly if not also doing the -, because it's balanced output.
Whatever reason for connecting the + output together for resistors is silly if not also doing the -, because it's balanced output.
Yes.
I don't think you need any resistors at all. Danny from GR Research didn't. He made a paid of monoblocks without them, and liked them.
Oh that makes it easy and sweet - just a few wires and solder bridges and I am set. I have a couple more amps I can try it out on then ans see if I notice and difference in SQ. Danny is really a good designer, and if he likes it then it must be fine.
I just went with this as a general tip fro Sreten for any type of stereo amp.
Thanks.
I just went with this as a general tip fro Sreten for any type of stereo amp.
Thanks.