| sled108 |
Are these worth looking into? A DIP8 chip with a Cmoy simple circuit.. 20W @ 4 ohm 9-24V?
How do they sound? I guess that's the big question... |
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| sled108 |
| Here's the Eval. Board Schematic... |
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| sled108 |
Oh well, so much for DIY....How can you do it yourself better than this..
The chip goes for $2.18 each...With $8.00 Handling + Shipping + Tax...
That's over $12 for the chips alone???
So, the next thing is to Hear how it Sounds...
Anyone heard one of these??... |
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| dweekie |
| I posted in the other thread, but it kind of sucks stock. :devilr: You should grab another one and go BTL, or try a hand at a dual supply design, but that would complicate things a bit more. |
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| sled108 |
Do you know how the 7720's Sound? Is it worth the trouble??
Are they on par with a TA2024?
If so, Than it's a whole nother story... |
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| lumanauw |
| BWRX can answer your question :) |
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| kenpeter |
TI's webpage offers tpa3122d2 in a
20pin DIP.
15W+15W, bridgeable... PDF seems
to suggest 40W into 8ohm 28V BTL
is quite reasonable.
Around 4 bucks last I looked, I dunno
which distributor or shipping to use...
I would suggest solder to a PCB with
a heatsink worthy ground plane.
The DIP boards I have worked with,
did not use a socket. I suspect that
decision to solder was intentional.
http://focus.ti.com/docs/prod/folde.../tpa3122d2.html
I've never tried MPS, I could not compare.
And to be fair, I rarely ever crank the
power supply past 12V unless a test
procedure calls for it. Its just too loud. |
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| BWRX |
| quote: | Originally posted by sled108
Are they on par with a TA2024? |
In my opinion, yes.
I was never able to obtain samples of the DIP8 package, only the SO8 package. |
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| sled108 |
The MPS7720 Amp arrived, 6 days from Hong Kong to NJ....Not bad...
It sounds nice right out of the box, smooth and tight with none of that 'new chip' harshness. It has plenty of punch on 14V and I'll let it burn-in for a while.
The only issue I've found is a really odd Cap discharge sound when turned off...Kind of Ray Gun like.
No big deal, but it would be nice lessen it. |
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| mobyd |
I notice that when you click the "buy" button on Monolithicpower's website, you get routed to Avnet USA as the vendor, and as a non US person (New Zealand) I'm very wary of playing the "Shipping will be calculated on despatch, just give us your credit card number" game of Russian roulette. Has anyone bought these (or indeed any other chips) from Avnet this way, shipping to a non US address, and how were the shipping charges. FFS Microchip Direct can work it out, why can't these guys.
Cheers
M |
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| lumanauw |
| quote: | | I notice that when you click the "buy" button on Monolithicpower's website, you get routed to Avnet USA as the vendor, and as a non US person (New Zealand) I'm very wary of playing the "Shipping will be calculated on despatch, just give us your credit card number" game of Russian roulette. Has anyone bought these (or indeed any other chips) from Avnet this way, shipping to a non US address, and how were the shipping charges. FFS Microchip Direct can work it out, why can't these guys. |
Once I buy this chip from AVNET, shipped to Indonesia. The chips cost me about US$75, but the shipment billing about US$125. I know the cost of the chips, but the shipment cost is not known until it appears in your credit card's billing. |
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| e_fortier |
Hi,
I just received 2 board from Sure Elec.
I have also noticed a cap discharge sound when turned off...Kind of Ray Gun like.
The Av gain is set too low so when you crank up the amp it creates some weird distorsion artifact. Based on the schematics I received from them (and the actual components on the PCB) the gain is set to 8.2 which is quite low compared to the T-Amp by sonic impact set at 21.6 or the one from Sure Elec. (TA-2024) set to 12.
f3 (input) is set at 16Hz and f3 (output) is set at 42Hz via the 470uF driving an 8 ohm load.
The sound is quite good and will be even better when I increase the gain to about 16-18 to avoid these nasty artifact spike.
It's too late now to give it a try but if anyone is interested I will report back. By the way the IC is surface mount type and not DIP8.
Regards,
Eric |
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| mobyd |
| quote: | Originally posted by e_fortier
Hi,
I just received 2 board from Sure Elec.
I have also noticed a cap discharge sound when turned off...Kind of Ray Gun like.
The Av gain is set too low so when you crank up the amp it creates some weird distorsion artifact. Based on the schematics I received from them (and the actual components on the PCB) the gain is set to 8.2 which is quite low compared to the T-Amp by sonic impact set at 21.6 or the one from Sure Elec. (TA-2024) set to 12.
f3 (input) is set at 16Hz and f3 (output) is set at 42Hz via the 470uF driving an 8 ohm load.
The sound is quite good and will be even better when I increase the gain to about 16-18 to avoid these nasty artifact spike.
It's too late now to give it a try but if anyone is interested I will report back. By the way the IC is surface mount type and not DIP8.
Regards,
Eric |
I have not had good results with these Sure Elec amps
This is what I got with a 24 volt supply and an 8 ohm load
The thing LOOKS competently laid out and they are claimed to
be tested.
M |
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| e_fortier |
Was your power supply regulated, it looks like at least 26Vpk to peak which could explain your problem.
Is this the glitch that we hear ?
Regards,
Eric |
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| BWRX |
| quote: | Originally posted by mobyd
I have not had good results with these Sure Elec amps
This is what I got with a 24 volt supply and an 8 ohm load |
The amps I made with the MP7720 used split supplies (+/-12V rails) and I never saw what your picture shows as the amp output. I tested them hard too, clipping into 8 ohm and 4 ohm loads and the chip got so hot I couldn't even touch it but the output was just a clipped sine wave. That could be the result of a problem with a component in the boost cap circuit. |
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| e_fortier |
Hi,
I have just finished to modify a Sure Electronics PCB that comes with 2 x MP7720 (7 USD + 5 shipping Intl) it is cheap fun for $12 USD
From a +18Vdc, 5A power supply I get 20W rms into 7.5 ohm just before any sign of clipping on the scope.
Modifying the unit is quite simple, a few component to remove, bypass the output cap and 2 x 2pF cap to add in the pre-filter feedback loop. I had the schematics for the PCB and thanks to BWRX I was able to synchronize both amp by looking at MP7731 IC, Thanks !
I'm missing the cap connected to the load, how do you calculate that one...
Regards,
Eric |
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| e_fortier |
| I forgot to mention that now instead of 2 SE amp I have bridge both amp for a single channel. :) |
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| mobyd |
| quote: | Originally posted by e_fortier
I forgot to mention that now instead of 2 SE amp I have bridge both amp for a single channel. :) |
Would you mind posting a schematic for the modded unit.
cheers
M |
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| e_fortier |
Hi,
While I do a nicer copy and scan the document, here are the required modifs.;
Remove the following components;
1. R2
2. R4
3. C5
4. R10
5. C14
6. C19
7. R7 and R13 (Zobel)
Bypass the following components;
8. C8 and C21 (output cap)
Add the following;
9. 0.68uF in parallel to the load (8 ohm min.)
10. 2pF film cap. from pin 7 (output) of U1 to pin2 of U2
11. 2pF film cap. from pin 7 (output) of U2 to pin2 of U1
12. small wire from pin 1 of U1 to pin 2 of U2
13. small wire from pin 2 of U1 to pin 1 of U2
That 's it, now Left input is the + audio signal and Right input is the
- audio signal (gnd)
Connect the loudspeaker between both speaker + terminals.
Enjoy :)
Regards,
Eric |
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| mudihan |
| If I were to use only one board for two channels, what is the list for the mods? Many thanks! |
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| mudihan |
| One more question: what does the 0.68uf cap do in the bridged version? |
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| e_fortier |
Hi,
This board already comes with 2 amplifier (single ended), the modifs shown above is to bridge both amp in order to get more power into 8 ohm but then it becomes a mono amplifier.
No mods required if you want to use these amp as stereo, except maybe for the output caps which are too small. Change C8 and C21 for 1000uF, 16V or 25Vdc. You don't need to de-solder them just push gently on the caps and they come right off.
The 0.68uF (I use a non pol. 1uF) is there to remove some high frequency from the output filter.
Hope this helps,
Eric |
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| sled108 |
| What is the purpose of C3? I can't find it on the schematic, is it a common to both channels Tank Cap that can be Super-Sized? |
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| mudihan |
e_fortier:
Many thanks!
You mentioned earlier that the gains are set too low. What are the resistors that needed to changed for a higher gain in a bridged version? Thanks again! |
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| perco |
Is it possible to use the sure electronics board as headphone amplifier? Has anyone tried? Is it possible after bridging it?
How does it sound? |
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| sled108 |
| It would be much more fun and easy to build or buy a Cmoy Mint Tin Amp such as this. You can also roll the chip with these to improve the sound according to you budget..Check E-Bay for Cmoy... |
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