I was happy with the sound of the stock TDA7297 I received last week. It was fast, full and had a tactile bass that I did not hear before from the small BR full range speakers I use . Normally I play a Max98400A Class D amp that I pulled from a dock. It's more transparent, but doesn't have the presence of the TDA.
I decided to remove the diodes and replace the power cap with a Pan FC, unfortunately something must've shorted at the speaker terminal (it was kind of loose) and now it only runs one channel. I tried resoldering the terminal block, but no luck. A new one is on the way.
I decided to remove the diodes and replace the power cap with a Pan FC, unfortunately something must've shorted at the speaker terminal (it was kind of loose) and now it only runs one channel. I tried resoldering the terminal block, but no luck. A new one is on the way.
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If you was happy with the stock lunch amp, why bother to bugger it up?
You should have ordered 2 amps, one stock that made you happy, and one to modify to see if it makes you even happier.😱
Point taken. I did think it lacked a bit of transparency, and there was some harshness in the mids. I have continued to listen to the 1 channel and found that replacing the input cap with a Vishay 1uf MKT has solved this. It came with 4.7uf electrolytics on the inputs. This is the same amp as 'hifix' as shown here (DC connector is handy) :
This version of the amplifier bypasses all the diodes with the use of the DC connector. Both diodes have since been removed (no jumper required).
The one on the left has the capacitor and terminal block swap.
What about removing the little ceramic near the diodes?
Thanks for your efforts, although it seems there are now more versions around.
Of the board (see above), mine does not have the same markings (C4 etc.) and slightly different layout/parts. Not a huge difference though.
djonesii,
Didn't you guys do a custom case?
Kudos to the father and son team, and have fun! 😀
On your board leave the resistors and the 33uf capacitor. The 2.2uf are replaced by the PHE426. The large one is replaced by Nichicon FG 470uf.
If you take a naked picture of the board without the pot or 1/8th mini jack, I can draw you a picture of what to do.
I figured those were for bypassing the main cap, so i left them in. I've been working on my 3116 amp, will get back on the 7297 real soon. The parts have arrived.
Bad idea, wiggle it till it falls off. You're hearing it ring and don't even now it till it's gone.
Yeah, we did a custom case, wired in with a IEC type plug, and a tiny bit of a passive preamp ...
Having a few issues with getting the full range drivers to play nice with the PVC, but as I get a bit of time, will post more images.
Dave
Is there a consensus on the maximum safe DC voltage for eBay 7297's, give they are all apparently seconds or rejects? How many users have had them blow up due to over voltage? Is it a voltage problem, or over dissipation? If the latter, maybe a bigger heatsink would ease the problem? Would be nice to get the max output......
Just about all consumer electronic products and many chips are produced in China or Asia. So are you saying there is some sort of chip conspiracy where the producers of 7297 amp boards sold on Ebay are purposely buying duff chips? What about AliExpress, the boards I have purchased from them have been just fine and probably come from vendors that sell on both sites.
The reason why you guys are blowing chips is because you expect too much from them and try to drive inefficient speakers to hifi levels with a chip designed for TVs and portable radios. You are probably also up in 10% THD which is hardly hifi.
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My chip from mouser did 23v for a week driving 87db speakers. I popped several chips from China when line voltage changed and they got a spec more than 18v. And I play loud often.
Some eBay ratings are now 12v.
You tell me...
Some eBay ratings are now 12v.
You tell me...
STMicroelectronics document the supply voltage for the 7297 to between 6-18v.
If you need to run 23v to get the volume you are satisfied with then you perhaps need a TDA7294?
I know you have a vested interest in the 7297 chip but the choice of speaker that can work with this chip are limited and efficiency generally means large and expensive.
Ebay perhaps rate the amp as 12v because power supplies of that voltage are common, inexpensive and work.
I didn't realize it was at 23v. The only reason that chip isn't still playing was a dead short on the DC that was from some wire that moved without me noticing.
Spec sheet says 20v max, operating 6-18v.
The mouser chips are better but cost 2/3 the price of a China unit. One could just solder one into the pcb. Difference in sound? I don't think they have the tone.
Spec sheet says 20v max, operating 6-18v.
The mouser chips are better but cost 2/3 the price of a China unit. One could just solder one into the pcb. Difference in sound? I don't think they have the tone.