Bought two of the famous Gainclone chipamps for testing - TDA7294 (left) 100w vs. LM3886 (right) 68w
An externally hosted image should be here but it was not working when we last tested it.
The output powers of the two chipamps (7294 & 3886) are virtually identical.
Look at the manufacturer datasheets.
The extra +1.7dBW (+32W) is not achievable for either device when ensuring the Maximum supply voltage is never exceeded; 3886 <=+-42Vdc, 7294 <=+-40Vdc
Most figures from both manufacturers are specified for Tj and/or Tc = 25°C and for 8r0 resistive loading using supply rail voltages specified AT the Supply Pins, not quiescent voltage at the PSU.
Look at the manufacturer datasheets.
The extra +1.7dBW (+32W) is not achievable for either device when ensuring the Maximum supply voltage is never exceeded; 3886 <=+-42Vdc, 7294 <=+-40Vdc
Most figures from both manufacturers are specified for Tj and/or Tc = 25°C and for 8r0 resistive loading using supply rail voltages specified AT the Supply Pins, not quiescent voltage at the PSU.
I wanted an 'ears on' feel with the debate of chipamps going on. Testing chip-amps with SMPS pair - one for each voltage rail. Speaker is Peerless 6.5" S16NI. Extra capacitance of 4700uf x2 & 0.1uf x1 per rail were added to reduce line ripple.
SMPS used - first 12v 3A x2 & then 19v 3.5A x2
SMPS used - first 12v 3A x2 & then 19v 3.5A x2
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The TDA7294 board made by XD218 (China) has NE5532 in the input stage & uPC upc1237 speaker protection & 3A diode x4 rectifier with 6800uf capacitor x2 regulator stage whereas the LM3886 made by Wintek (India) is a 'no frills' board.
The TDA7294 is designed to be connected AC 28v-0-28v transformer supply
To test it with SMPS I had to bypass the relay of the TDA7294 board since it is 24v & engages for input volt >25v only.
On playing music, the TDA7294 I felt emphasizes the base (could be due to the additional input stage) whereas LM3886 the mids & highs.
With 24v (12v x2) 3A both sounded the same volume whereas with 38v (19v x2) 3.5A the TDA7294 sounded louder with more speaker excursion. Also at 38v 3.5A LM3886 dissipates a lot of heat even at low volumes more than TDA7294.
To check the susceptibility to DC power fluctuation I cycled the power on/off 3 times in 5 seconds. The TDA7294 was blown instantly whereas nothing happened to LM3886. I even switched off one SMPS rail & still no problem for the LM3886. It is much more robust than TDA7294
To check whether the SMPS & bypassed speaker protection circuit caused the failure of TDA7294 , I had a 28v-0-28v transformer custom made & connected to another TDA7294 XD218 board. The speaker protection circuit worked fine with a 3 second initial power on-delay & music played fine. However when the input power was rapidly cycled as before it blew !
The TDA7294 is designed to be connected AC 28v-0-28v transformer supply
To test it with SMPS I had to bypass the relay of the TDA7294 board since it is 24v & engages for input volt >25v only.
On playing music, the TDA7294 I felt emphasizes the base (could be due to the additional input stage) whereas LM3886 the mids & highs.
With 24v (12v x2) 3A both sounded the same volume whereas with 38v (19v x2) 3.5A the TDA7294 sounded louder with more speaker excursion. Also at 38v 3.5A LM3886 dissipates a lot of heat even at low volumes more than TDA7294.
To check the susceptibility to DC power fluctuation I cycled the power on/off 3 times in 5 seconds. The TDA7294 was blown instantly whereas nothing happened to LM3886. I even switched off one SMPS rail & still no problem for the LM3886. It is much more robust than TDA7294
To check whether the SMPS & bypassed speaker protection circuit caused the failure of TDA7294 , I had a 28v-0-28v transformer custom made & connected to another TDA7294 XD218 board. The speaker protection circuit worked fine with a 3 second initial power on-delay & music played fine. However when the input power was rapidly cycled as before it blew !
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Though the TDA7294 had ST Microelectronics logo on them it I doubt its authenticity.
Another factor I noticed is the speaker on/off pop noise is more for TDA7294 whereas LM3886 is silent. Sometimes the off pop noise is too loud to being irritating.
Regardless of the fact I like the sound signature of TDA729x series - punchy base with soft treble, am unlikely I will tread in their path again due to instability issues.
Another factor I noticed is the speaker on/off pop noise is more for TDA7294 whereas LM3886 is silent. Sometimes the off pop noise is too loud to being irritating.
Regardless of the fact I like the sound signature of TDA729x series - punchy base with soft treble, am unlikely I will tread in their path again due to instability issues.
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Do you use the Stb/mute function?
I have not noticed any on/off pop noise during my tests. Maybe because of this (Stb/mute function desactivations or wrong implementations) your IC was destroyed. In the datasheet there are some interesting info regarding this function.
In the last two years and might not be the foremost search results, finally a basic build (philfr) and a nested build (neurochrome) have resulted in practical, as in enjoyable, output from the LM3886. I am simply saying that a potentially delightful output from the LM3886 is possible and proofed as well even though I don't expect that to be representative of the typical usage. I contributed slightly and interfered a lot more because of curiosity. Even though I didn't like the parts they used, I have to say that the resultant output worked perfectly fine, in those two specific examples.
And, if comparing the LM and the TDA optimized stable examples, while driving a real speaker, ought to result in exactly the same output, albeit by slightly different means.
So, although optimized examples are rare, what I had meant to say is that comparing them would be waste of your time.
For the optimized examples, output of a real music signal to a real speaker is. . . exactly the same.
Sanken's original and fake are difficult to distinguish - go to
Counterfeit Transistors
but the good news is to know a trusted delivery source (ordering address):
Profusion Audio Semiconductors - Buy Online (distributor for SANKEN power devices).
From where I can currently order genuine ST versions of the TDA7293/TDA7294 and genuine TI versions of LM3886 without any headache ?
Thank you for your advices.
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