@gmarsh,
To use the differential inputs on your amp board (via a transformer), one has to remove the input film cap?
Thanks!
Regards,
To use the differential inputs on your amp board (via a transformer), one has to remove the input film cap?
Thanks!
Regards,
I thought the "science" was in the design of the chip rather than the shuffling of various brands of components.😉
You don't strictly have to, you can just hook the transformer outputs to the wiener's input terminals and it'll work fine.
Each input has a 30K resistor and zener ESD protector to ground, and a 2.2uF film cap to the INx input of the IC. Resistor and ESD protector shouldn't create any audible effect in this scenario, but the series C will give you a highpass filter at a couple Hz... not that that matters much as the transformer itself probably acts as a higher frequency highpass than it.
It is safe to bypass the input caps with the transformer in the signal path. I suggest you try it both ways and then report back on your findings. I already know what you will find, but don't want to pre-empt anything.
Try not to get too sucked in by the "science", it's about as scientific as adding a few after market products to your vehicle.
I wonder if the engineers at TI ever check out the pages and pages of discussions that their chips has created?😉
Well, they should read and think about their crappy/not so good power on/off solution within the TPA series. Maxims implementation is a lot better.
OK gmarsh, if you wish, I will share my experience of those 15k:15k Edcor transformers between my DAC and valve preamp. I just thought that if someone were to do the experiment themselves, right now, with this particular board, it would carry more weight and be more relevant to this thread. Interested?
The power these things draw, it seems hardly worth the effort to turn them off.
I hope you pull out your wall wart after switching off?
I leave my preferred stock TDA7297 on permanently, it is absolutely dead quiet and I have noticed no increase in my hydro bill.😉
Firstly, it has been my experience that every capacitor, no matter how "good", how expensive, or how "audiophile", has an effect on the sound of an analog signal passing through it. Valve amp aficionados use the different kinds of capacitors to "tune" their systems to their liking. Compared to a capacitor, a transformer is relatively far more neutral, consisting of nothing more than lots of wire and a magnetic field. Eliminating capacitors from the signal path must have a beneficial effect on the clarity, openness and accuracy of the signal that is about to be amplified. In a decent amplifer, this will be immediately noticeable. However if the amplifier sounds coarse, harsh or screechy, the veiling brought about by a capacitor/capacitors in the signal path may be doing the listener a favour. In my case, after spending an obscene amount of time, money and effort in trying all sorts of coupling capacitors, substituting them with the transformer was one of those "hallelujah" moments one gets occasionally in this hobby which in turn make it so rewarding. Another point I have not seem much mention of in this thread is just how much better a stepped attenuator sounds than a carbon-track pot. I don't yet own one of these amplifiers, so maybe I am barking up the wrong tree here, but if these amps are as good as people seem to find them, it ought to be worth using something other than a carbon pot - even an expensive one like Alps. I had Alps black and Alps blue pots in my preamp and the difference when fitting an attenuator was another of those "AHA!" moments. Sorry, no science, no measurements and no blind testing. Just personal observation.
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It is not about the quiescent current, it's about their power-on/off cycling - system startup/shutdown. It actually doesn't handle SE very well for normal time constants or imbalance at the input. There's a lot of trouble, even here in this thread complaining about pop/click etc.
Of course, there are solutions available but they eat up board space and, due to part count, increase statistically faults/failures. I.e. Maxim ICs have (patented) "click-pop-suppression" which do a bit more than having a power-on-delay. (Where this is fixed to 10ms at the TPA, Maxims i.e. 9709 features a dedicated delay pin for a dedicated timing capacitor) - Beside this, they don't need 4 bs-caps. 🙂
Yes indeed it seems that you think that that is the only scientific part.
I will try to help you a little bit:
Science - Simple English Wikipedia, the free encyclopedia
Good luck! 😉
I am pretty sure we can do without the "simple" part. And I assume we are all familiar with the scientific method.
What is "scientific" or evidence-based about the tweaking of secondary components without proper understanding of the theory behind the primary functions?
Perhaps just the first part of 'aural' observation. 🙂 But then you have to address 'expectation bias'. That's not so easy to walk away from. I think it alone plays a huge part in what we hear - or better yet, what we WANT to hear after we make a mod.
Unlike say, medicine that is not an exact science, electronics is. Math and physics for the most part. Math and the physical makeup of the components make audio predictable IMO. Component A will have the exact same effect, if placed in the exact same circuit. Emphasis on exact. What anyone 'believes' the affect will be is of little value to the predictable results that science knows it will have. Measurements matter. And further more, the 'chain of custody' of the originating signal must not be tampered with in any way, if you're trying to perform some level of scientific evaluation on the affects your mod just made. Same source, same cable, same speakers, same everything except the mods. I would prefer to make measurements before and after and compare the results on paper, to what you think/did hear after the mod.
I think it's harder and rarer than most people are willing to admit. 😀
willward, you just got me interested in those capacitor/transformer replacements, as well as attenuators for pots...
Can You point me into reading more about it, more from practical standpoint, any example schematics or so... I am just a beginner in electronics, but I wan't to know how I can tweak my sure tpa3116 board, 6N3 preamp and 1036 tone board combo to get even better sound...
TIA
...don't forget the magnetic core that undergoes hysteresis/saturation, which varies with music envelope and frequency content.. leakage inductance that forms a filter in conjunction with the input/output impedance, pickup of external EM fields, and I'm probably missing a few other effects. Transformers are by no means transparent, and distortion that they cause can definitely make an audible effect in the sound of a piece of equipment.
Though distortion can sound great (SRV's guitar tone is a clipping op-amp...), and distortion can also mask worse sounding distortion that exists in the recording or is created elsewhere in the playback chain. So transformers very well can make something sound "better" due to their distortion - if you installed one in your playback system and it sounds better to you, I can't say you're wrong.
And capacitors can be bad too, both measurably and audibly, if you pick parts with the wrong characteristics for the application you're putting them in. And they can be very much transparent if you use the right ones. Say a cheap TPA amp uses 6.3V X5R's for its input coupling caps, they could make an audible effect on the sound, because said 6.3V/X5R's will probably have significant leakage current at the DC bias applied, not to mention dynamically changing capacitance due to C/V effect. Remove the caps and install film caps in their place, it'll work a whole lot better. Or remove the caps and wire in a transformer, hey, it'll probably work better too...
"Capacitors bad, transformers good" is a gross simplification and not particularly useful if you just leave it at that. Dig deeper than that - spend some time figuring out the underlying reasons why you hear what you hear when you change things, ultimately there's an explanation for everything, and lots of things to be learned that can lead you to make even better equipment.