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Old 14th July 2013, 03:48 PM   #501
Lo_Tse is offline Lo_Tse  Canada
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Quote:
Originally Posted by danielwritesbac View Post
No, I didn't need it yet. Looks fine though.
Either of those parallel boards could use this schematic, except that the 3-chip model would have a 100uF bootstrap cap.

My 70's receiver-amp refit project has a custom fit center tap transformer, previously powering 55 watts per channel with frail discrete amp, now powering 90 watts per channel with the durable 2-chip TDA7293 parallel boards. Due to the transformer amperage capacity, I didn't need the 3-chip boards at this time. And, now I find out that the smaller 2-chip parallel units easily exceed the capacity of my speakers.

P.S. I bought a box of TDA7293 chips to play with for parallel amp point to point projects, so it is unlikely that I'll need boards for some time. More powerful speakers probably comes first.
Daniel,

Thank you for you comments. Interestingly. P to P is very probably very "doable" with these amp since they are so compact and do not need that many components.

Keep us posted!

Regards,
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Old 17th July 2013, 09:20 PM   #502
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Default What to do with those bad layout single-layer boards? Probably this:

To get a nice sound from the TDA7294 treble, my older design is like this:
Gain divider: Feedback resistor 114k vs Feedback-shunt resistor 2.7k
Signal caps: NFB-shunt cap 243u, input cap 0.68u and a tiny polyester bypass for both
Power caps: 220u per rail (can add either diode isolators or rail to rail cap)
Input: either blarebuster 1 or lightspeed attenuator

That can be used with:
Poor Layout boards can use it well, due to the different harmonics.
If you want 6-1/2" and smaller speakers to play clear and Very loud.
Point to point builds, easier to build with the tiny size capacitors.
Concert duties for little monitors or for multichannel midrange & treble arrays.

A sound reinforcement favorite for many years, that older design, is sensitive and has a different sound. if there's one special combination of cap and resistor values that you can plug in to a bad layout single layer board to cause it to sing or be useful, this is it. Component values described at the top of this post.


Alternatives:
If the above doesn't do it, then I'd suggest one or both of the following options:
1). Throw the board away and use the chip point-to-point, aka no board sound at all.
2). Or use this much cleaner sounding board, since compact dual-layer sounds like point-to-point.
Notes:
The majority of "amplifier tone sounds" is not in the chip, but actually most of the tone variances are from board layout and power circuit, especially power layout of the amplifier board and the "fix" for that is selecting a really favorable board.
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Last edited by danielwritesbac; 17th July 2013 at 09:24 PM.
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Old 10th August 2013, 07:27 AM   #503
Gost22 is offline Gost22  Bolivia
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Thumbs up AComplete audio amplifier with TDA7294

Hi guys!
Here I've made audio ​​amplifier with TDA7294 and it works great!
This amplifier is complete with power supply!
Greaz of 8A and 600V
2 electrolyte of 4700uf/50V.
I enjoy the sound!!
cheers!
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File Type: jpg P1110750.jpg (508.0 KB, 424 views)
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Old 11th August 2013, 06:11 AM   #504
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Very interesting! That's Surprisingly compact for single layer! Do you have PCB layout photos for it?
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Old 11th August 2013, 06:32 PM   #505
Gost22 is offline Gost22  Bolivia
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Quote:
Originally Posted by danielwritesbac View Post
Very interesting! That's Surprisingly compact for single layer! Do you have PCB layout photos for it?
PCB layot is in Protel 98
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Old 12th August 2013, 03:54 AM   #506
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Quote:
Originally Posted by Gost22 View Post
PCB layot is in Protel 98
Can you open it and then hit printscreen, paste into photo editor, and then make screenshot photos of the layout?
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Old 12th August 2013, 07:47 AM   #507
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Quote:
Originally Posted by danielwritesbac View Post

<<<<< snipalot

2). Or use this much cleaner sounding board, since compact dual-layer sounds like point-to-point.

end snip >>>>>>
Hi Daniel !

Interesting. Are you endorsing this particular board / supplier?

I am not trying to catch you out, it's just that it would be nice to identify a good, low cost and trustworthy chipamp kit. It might benefit a few people to know.



Rgds,
blakkintosh
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Old 13th August 2013, 09:59 AM   #508
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Yes, I have been endorsing a very compact layout for cleaner power, And parallel amp for enhanced output device linearity. That means, Compact Parallel amp is the highest quality for TDA7293. So I contacted Zoe Tsang (Not a financial affiliate) and requested this listing: Two board *stereo* kit TDA7293 Parallel amplifier
And I made this schematic.
And I made these assembly photos.
It is also in my signature line.

When using my schematic, power circuit and power supply:
Dynamics: Exaggerated and/or High End (suitable for music replay)
Tone: Very High End--maintains pleasant tone all the way to the rails
Clarity: It could beat an STK, probably (better than a midfi)
Power: 70 watts to 8 ohms, 90 watts to 4 ohms, 130 watts to 4 ohms
Usage: The dance floor of a pub or a small nightclub (big houses too)

Double check: This amplifier is not suitable for critically dissecting music for an autopsy/analytics. And despite the pleasant tone and deceptively small size, the little thing is extra powerful, so it is not suitable for apartment dwellers because the neighbors will hear it. All of them. However, it can do enthusiastically well for fun, loud, and lively concert sound.
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Last edited by danielwritesbac; 13th August 2013 at 10:13 AM.
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Old 13th August 2013, 12:04 PM   #509
Gost22 is offline Gost22  Bolivia
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Quote:
Originally Posted by danielwritesbac View Post
Can you open it and then hit printscreen, paste into photo editor, and then make screenshot photos of the layout?
Rear of PCB,...PCB-top,...
Attached Images
File Type: jpg PCB with TDA7294.JPG (666.7 KB, 350 views)
File Type: jpg BCB-top.jpg (356.7 KB, 329 views)

Last edited by Gost22; 13th August 2013 at 12:17 PM.
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Old 13th August 2013, 01:53 PM   #510
jayadev is offline jayadev  India
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4700mf capacitor is not at all enough for this chip amp. minimum is 10000mfd.considering the output mosfets.

a short length of cable from power supply to amp board acts like choke filter which I always found healthy in all my amps,which means I will keep the Ac diodes far away from chip.

what I mean is, one should try connecting the scope to power lines and see with music on.
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