The amp is dependent on keeping voltage high since it's current limited, so yes it requires quiet a bit of backup. But that's not the only way to do it.
Wow. That amp is over 10x the cost of the ones we are discussing here.
Also, that amp is based on TPA3116/8, of which I already own one board (which I fried because it was wired wrong from the shop) and have ordered another through a local group buy.
I'm specifically interested in these little 7297 amps because they are hilariously cheap and tiny. Anyway, I have two on the way for less than the cost of a big sandwich, so time will tell whether one makes it to my "garage system".
Maybe will help me with the speakers too.. cuz I-m a true beginner I that area..
If Thiele/Small parameters are available for those drivers, I could give you an idea of a simple bass-reflex box. However, it appears as though they only go to 7000Hz, which means you will (probably) want a tweeter. That makes things a bit more complicated.
Now they's even cheaper.. And upgraded too..
TDA7297 Version B 2 15W Digital Audio Amplifier Board Dual Channel AC DC 12V BX | eBay
TDA7297 Version B 2 15W Digital Audio Amplifier Board Dual Channel AC DC 12V BX | eBay
Do note that the cheapest ones are listed as 12v. Someone previously noted that the "original" ebay versions smoked after 18v, suggesting ebay sourced chips are from the reject bin to begin with. I think with the recent cheaper 12v versions that you're probably dealing with the second tier of the reject bin, rather than some seller trying to encourage business by using a "friendlier" voltage number. May sound fine, but my guess is that if you don't observe the rating you'll be a bag of chips and a drink poorer. Still may be quite the bargain, though
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I've been running one of the $3 ones at 16.5v (regulated) for several hours and it seems to be ticking along just fine.
However, the input voltage polarity is mis-marked on the pcb - took me a while to figure that out, and in the process it fried two tiny transistors on the outputs of my miniDSP. The amp must have somehow been dumping voltage back toward the miniDSP via the line level connection.
Note to self; do not test questionable gear with other equipment.
Now I have another project in the queue, and it looks to be very challenging.
However, the input voltage polarity is mis-marked on the pcb - took me a while to figure that out, and in the process it fried two tiny transistors on the outputs of my miniDSP. The amp must have somehow been dumping voltage back toward the miniDSP via the line level connection.
Note to self; do not test questionable gear with other equipment.
Now I have another project in the queue, and it looks to be very challenging.
On another note; I'm pleasantly surprised at how good these amps sound, all things considered. Certainly they have significant limitations in both power and fidelity, with the latter dropping rapidly as the former is pushed passed about 4 watts.
But for $3 (!), that first watt or three is very, very pleasing. Furthermore, the size of the unit creates all sorts of possibilities:
Some careful trimming of the PCB with sheet-metal cutters allows the amp to fit into a tiny tea tin. Sort of like those headphone amps in Altoids tins.
All I need is a power header and some appropriately-sized speaker terminals. Planning to use angled aluminum to sink the heat into the "chassis".
Perfect little bathroom amp.
For the garage, I'll find a more "manly" tin.
But for $3 (!), that first watt or three is very, very pleasing. Furthermore, the size of the unit creates all sorts of possibilities:
An externally hosted image should be here but it was not working when we last tested it.
Some careful trimming of the PCB with sheet-metal cutters allows the amp to fit into a tiny tea tin. Sort of like those headphone amps in Altoids tins.
All I need is a power header and some appropriately-sized speaker terminals. Planning to use angled aluminum to sink the heat into the "chassis".
Perfect little bathroom amp.
For the garage, I'll find a more "manly" tin.
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For the last 2 years this little amp has been driving a huge pair of 15 inch Tannoy York speakers and to me the sound is fabulous.On another note; I'm pleasantly surprised at how good these amps sound, all things considered. Certainly they have significant limitations in both power and fidelity, with the latter dropping rapidly as the former is pushed passed about 4 watts.
But for $3 (!), that first watt or three is very, very pleasing. Furthermore, the size of the unit creates all sorts of possibilities:
An externally hosted image should be here but it was not working when we last tested it.
Some careful trimming of the PCB with sheet-metal cutters allows the amp to fit into a tiny tea tin. Sort of like those headphone amps in Altoids tins.
All I need is a power header and some appropriately-sized speaker terminals. Planning to use angled aluminum to sink the heat into the "chassis".
Perfect little bathroom amp.
For the garage, I'll find a more "manly" tin.
You need to get away from those little pisspots.
With a regulated and well maintained voltage fed from a capacitor multiplier, the amp actually performs very well in the entire spectrum of it's power. It's plenty good to enjoy music at a hi-fi level even with 87db speakers as one's main amplifier.
Put it in metal enclosure for better sound! And yes the parts on the boards need replaced. It needs 1-2uf input caps for bass (must be film for best performance due to a polarization effect)
Put it in metal enclosure for better sound! And yes the parts on the boards need replaced. It needs 1-2uf input caps for bass (must be film for best performance due to a polarization effect)
I listened for several hours this evening. Eventually, fatigue set in and I reverted back to my tube amp. My entire body felt the difference.
SS "volume" is measured in dB.
Tube "volume" is measured in cubic feet/meters.
That's the best I can do to describe my subjective experience. Well worth the electricity cost, to me.
SS "volume" is measured in dB.
Tube "volume" is measured in cubic feet/meters.
That's the best I can do to describe my subjective experience. Well worth the electricity cost, to me.
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Sorry,
I thought those little cans in the image were those small bluetooth speakers being produced.
My unmodded 7297 amp, for the last 2 years has been left powered up permanently, it runs absolutely dead silent, unlike tube amps.
The 7297 replaced a McIntosh MA 6100 as an experiment and was immediately made permanent.
OK, the Mac could well be out of spec after all these years but I see no reason to spend on it, I just love the 7297 and the space vacated by the Mac now houses dozens more CD's.
I was about to sell my old vintage speakers, I was offered an insane sum for them but refused after I had connected the 7297, the speakers have never sounded better.
Being retired, I have spent a lot of this bloody cold winter just listening to music and I have found the 7297 to be not in the least tiring
I gave up on tubes almost 30 years ago, I did not think they were worth the effort. I also reached the same opinion on playing records, but I really tried to hear what the analog guys were hearing but noise got in the way.
It's all subjective.
The little cans are amp chassis.
I think I need to be clear that I do think these little amps sound excellent for what they are. The fact that I listened for several hours last evening before getting brain fatigue is a testament to the sound quality. By no means have I given up on or dismissed these amps. I have tried other amps that only lasted a few minutes.
Subjectively, my tube amp simply fills the room with incredibly clear, sweet sound. There's just something that feels so much more "real". No, I can't prove it, but that's the nature of subjective evaluation.
I asked my young daughter what she thought. " It sounds really good, but the voices aren't as clear- like they are farther away - S sounds do not sound sharp and clear enough..."
She's used to hearing my tube amp many hours per week.
But still, these are really good little amps for $3. Incredible, actually.
Note: so far I have taken some of the advice in this thread and done the following mods:
- removed the diode
- replaced the input caps with 1uF film
- replaced power tank cap with 9500uF (see pic )
- technically, the volume pot is not in play as it is running wide open (feeding it with a pre-amp)
Power supply is a 19v HP laptop SMPS being regulated down to a little over 16v by an LM317. At "very loud but not clipping" volume, the chip runs well within temp spec. Much of this can be seen in the photo.
I think I need to be clear that I do think these little amps sound excellent for what they are. The fact that I listened for several hours last evening before getting brain fatigue is a testament to the sound quality. By no means have I given up on or dismissed these amps. I have tried other amps that only lasted a few minutes.
Subjectively, my tube amp simply fills the room with incredibly clear, sweet sound. There's just something that feels so much more "real". No, I can't prove it, but that's the nature of subjective evaluation.
I asked my young daughter what she thought. " It sounds really good, but the voices aren't as clear- like they are farther away - S sounds do not sound sharp and clear enough..."
She's used to hearing my tube amp many hours per week.
But still, these are really good little amps for $3. Incredible, actually.
Note: so far I have taken some of the advice in this thread and done the following mods:
- removed the diode
- replaced the input caps with 1uF film
- replaced power tank cap with 9500uF (see pic
)- technically, the volume pot is not in play as it is running wide open (feeding it with a pre-amp)
Power supply is a 19v HP laptop SMPS being regulated down to a little over 16v by an LM317. At "very loud but not clipping" volume, the chip runs well within temp spec. Much of this can be seen in the photo.
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I suggest that the biggest improvement to this amp would be replacing the chip with one sourced from a proper supplier.
All big suppliers have this chip at 5.5$-4.5€. Go figure...
You are actually admiring how good a "reject" part can sound. Some of you have failed chips ... Or they fail short term.
Sure, you can have a reject that works, and even sounds great. But here math applies as well. You have to take into account that the seller earns money at 3$ for the whole board!
Also it seems there's a lower power tda7297sa (10W instead of 15w, cheaper as well)
http://www.mouser.com/ds/2/389/stmicroelectronics_cd00004985-490192.pdf
First mod -> proper chip.
If you are curious buy/make your own boards, but I think it's cheaper to get the 3$ amp just for the board. Get a proper chip from a reputable dealer and then make an opinnion about this chip.
All big suppliers have this chip at 5.5$-4.5€. Go figure...
You are actually admiring how good a "reject" part can sound. Some of you have failed chips ... Or they fail short term.
Sure, you can have a reject that works, and even sounds great. But here math applies as well. You have to take into account that the seller earns money at 3$ for the whole board!
Also it seems there's a lower power tda7297sa (10W instead of 15w, cheaper as well)
http://www.mouser.com/ds/2/389/stmicroelectronics_cd00004985-490192.pdf
First mod -> proper chip.
If you are curious buy/make your own boards, but I think it's cheaper to get the 3$ amp just for the board. Get a proper chip from a reputable dealer and then make an opinnion about this chip.
Why a metal enclosure? My board is Au Naturel and works just fine, no RF noise as from a D-amp.
I get some RF because of my area, but even if it's not audible, the sound is improved the more I increase coverage. Imaging improves without a doubt, and lower fatigue.
For giggles, I just removed the 9500uF tank cap and replaced it with a Mepco/Electra 100vdc 30,000uF beast. Yes, thirty thousand. The thing weighs 660 grams. It looks hilarious connected to the 7297 amp!
It sounds fantastic. The bass has some very impressive grunt. Overall, the sound is "richer" and smoother. I honestly cannot believe what I am hearing!
It sounds fantastic. The bass has some very impressive grunt. Overall, the sound is "richer" and smoother. I honestly cannot believe what I am hearing!