The FA board is star grounded.
I understand the point of separate ground pins. You need to take up the issue with STMicro however. Go ahead and make your own board, order a thousand of them, they'll all be dead if you don't make them connect with an uninterrupted path.
I'll point out the chip also has two Vcc pins, but odds are that one is just the Vref, since the resistance between the two is 1.1ohm; and if there were room that could've been done internally.
Hi,
Quite frankly I'm giving up, your in serious denial of anything sensible.
SG entry point is fully floating off the chips SG pin, your wrong.
Its not properly wired correctly. SG entry point should go to
star ground and then be the only connection to the SG pin.
(As shown in the datasheet.)
rgds, sreten.
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No I'm not. Have you been playing with these chips for over a year? NO. Do you even own one? You're trying to force a fantasy of what you want to be true. I'm offering information that might boggle everyone that wants to play with the chip for an outstanding length of time because of an incorrect datasheet. But by all means prove me wrong, throw your money at the wall all day! Even the other guy on here who made his own PCB has his SG connected to circuit ground and his works. The only joke here is that you trust a data sheet more than hundreds of working PCB's and three fellow DIYaudio forum members with their own working boards.
http://www.diyaudio.com/forums/chip-amps/242000-tda7297-board-layout-suggestions-2.html#post3623325
http://www.diyaudio.com/forums/chip-amps/226688-tda7297-ground-paths.html#post3304387
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What about basic things like the make, type and values of the potentiometer, resistor and capacitor.
What did you use as a source, cables and layout?
Did you make any measurements?
Hi,
I'd say it would seem to most that is your problem not mine.
You don't seem to have any grasp of why the chip has separate
ground pins and how to use the feature effectively. You seem
to be baffled as to why the grounds are not independent, when
that clearly is not the intention, and they must be connected.
If you've built the layout in the datasheet and still have
problems you might have a leg to stand on, but you
haven't by all indications, and can't disparage it.
rgds, sreten.
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I'm currently using a DACT Chinese stepped attenuator (found on Ebay), had been using a Dale stepped attenuator off of Ebay, and Dale resistors from mouser for inline. Also used were a tube preamp with Alps Blue velvet (commercial unit), and a Bel Canto DAC3 (as volume and source).
My source is a Bel Canto CD1, but other sources with the tube preamp were used and unknown to me. I've also tried my cellphone
and my Sony XD HD tuner (whatever the one everyone wants is, forget the model). My input capacitors were Wima MKP10's, PHE426/450, Mundorf MKP, and Orange Drops. The Wima's and Mundorf's were the worst with the combination. I tried a few other things but they're not important. A miss on the wiring once caused me to have Muse ES electrolytic capacitors in series with the Wima MKP10, and it sounded better than the Muse ES alone (which seem to polarize it seems).
My cables are BJC interconnects. Others used I'm not sure on. Speaker wire doesn't seem to matter to much, White Lightening and Analysis + former high end cable mostly. I did try some XLR cable but ultimately it was a band-aid help prior to understanding the issue with resistors. I had believed the Dale stepped attenuator was the problem itself, until a reoccurrence occurred with another system.
I don't own the equipment to take the measurements for the phenomenon itself, but no notable stray DC or AC currents were found, and no abnormal connections between signal wires or output wires, and other parts of the amplifier.
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This looks like a change of story, since now you're saying they do need to be connected.
If they are connected, are you proposing that SG in go to a star point that's on/off the CG circuit pin, and then another leg goes to the SG pin. That is opposed to the SG in pin being ground star? That's a very different argument than claiming they should not be connected; which is typically the case we're use to.
Figure 3b doesn't show star grounding. Mine is at SG in pin.
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Hi,
I've being saying all along they shouldn't be connected at the chip
which you have been studiously ignoring as simply being not connected.
Your mistake and misinterpretation not mine. I've been consistent.
In the datasheet they are separately connected to the star point.
rgds, sreten.
I've being saying all along they shouldn't be connected at the chip
which you have been studiously ignoring as simply being not connected.
Your mistake and misinterpretation not mine. I've been consistent.
In the datasheet they are separately connected to the star point.
rgds, sreten.
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The discussion is the effects of different types of resistors/volume devices, causing abnormal sound. It's been largely centered around the possibility of parasitic capacitance/oscillations on the output, like from a shield on the output wires.
Someone in another thread pointed out that the amplifier is responsive well up to 100khz and perhaps beyond. Out of curiosity (and while not able to replicate the original issue at the moment with my enclosed amplifier gone) I put a 600pf cap across each input to ground. I think it would be much too large with anything above a 10k volume, but as is I need to listen to some familiar music. This was suggested to me by someone else, to perhaps help with the occurrence. Even if it's not solving an issue that isn't around without a shield (potentially), it may be a benefit overall.
Yes, it has appeal. Perhaps my issue wasn't with it specifically, but at some point you have nothing but muddiness and bass with this amplifier. When it plays well it is very pleasant, so I'm not worried about trying to add it. One can always use a tube pre.
The lower end is just fine when there's no issue. But it would appear a capacitor actually is an aid to the quality of the sound.
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