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10 watts of broad spectrum RF energy that is transmitted outside the unit would wipe out all kinds of communications within at least hundreds of yards - cell phones, police, fire, etc. Even two watts would create big problems. Nothing like that would comply with FCC emission standards.
There's no way this kind of energy is getting outside the SA-60's case.
***
Everything in electronics design (and life) is about trade-offs, pluses and minuses.
So, the first question is whether the air core inductors in the SA-60 create radiated RF noise problems - my tests say it does not.
As to ESR: core inductors have several kinds of losses that contribute to ESR that do not affect air core inductors: hysteresis, eddy current, proximity and skin effect. Because of all these factors, core inductors often have higher total ESR than air inductors.
As I see it, using air inductors as in the SA-60 is a reasonable approach taking into account the pluses and minuses. The bottom line is that it works great in my system without any noise issues. I'll be running more tests and trying it out in other setups, and if there are any problems I'll report back. Also, I plan to try out other 3116 boards which include core inductors and will be able to compare them. By the way, I've have Class D amps here using solid core inductors that have radiated noise problems - there are lots of design issues that affect the noise issue.
I know. That's why my comments are generalized. You can design class D amps with air core inductors that don't have EMI issues and that do sound good. They would be rare. On the other hand, you also can design class D amps with toroid or shielded core inductors that do have EMI issues and that do not sound good (or at least as good as they could).
Since this is DIYaduio the general advice is to not use air core inductors in class D amp designs but use toroids or shielded core inductor specifically designed for this use.
I tried doing some trace finding for Sure board. I know picture is a mess, but it gives some idea where everything is going.
I find parts marked as TVS1 and TVS2 very interesting, because the way they connect to inputs. On the part is reads 5A6Σ (or 546Σ). Might this part been used by Sure in hopes it would reduce turn off pop? I didn't find any datasheet for the part, but using multimeter I can find two diodes with forward voltage of 1,174V.
I guess Q1 (near power jack) is just used for LED, Q2 is for mute function when MUTE pin is connected to GND (absolutely not sure about this).
All traces might not be correct and I could be wrong about the part, but what you guys think?
Better pictures for the board are here.
I find parts marked as TVS1 and TVS2 very interesting, because the way they connect to inputs. On the part is reads 5A6Σ (or 546Σ). Might this part been used by Sure in hopes it would reduce turn off pop? I didn't find any datasheet for the part, but using multimeter I can find two diodes with forward voltage of 1,174V.
I guess Q1 (near power jack) is just used for LED, Q2 is for mute function when MUTE pin is connected to GND (absolutely not sure about this).
All traces might not be correct and I could be wrong about the part, but what you guys think?
Better pictures for the board are here.
Attachments
Apologies for the bad links in my post -- here they are fixed.
SMSL SA-60 60WPC TPA3116 Class D Digital Amplifier HiFi Air Core Inductance Desktop Amplifier - Professional Audio Store - Shenzhenaudio.com
Amazon.com: SMSL SA-60 60WPC Class D Digital Amplifier silver: Electronics
I do have a couple of issues with the SA-60 amp - but not about its sound quality or freedom from radiated or internal noise (in both respects I think it's excellent). My complaints are about functionality issues.
First, the speaker binding posts on the back are reduced size. This was a necessity because of the small size of the case. However, it's dangerously easy to short out the speaker connectors with normal size spades or bare wire. Insulated banana connectors are probably the safest connection to use - though they are not my favorite. The electronics could be put in a larger custom cabinet with standard size binding posts - but that defeats the point of buying a finished amp (and the finishing on this amp is quite nice).
Second, the amp is really set up to be used as an integrated amp rather than a standalone basic amp. It has two inputs, front and back, which are switchable (a nice feature for an integrated amp). However, I want to use it as a basic amp with my HTPC analog output acting as preamp. I also want to turn it off when not in use (I'm pretty careful about minimizing unnecessary electric power usage - though I realize the 3116 draws only about a half watt when turned on but not in use, I'd rather save that power).
When the amp is turned off, and then turned back on, the volume is automatically reduced to a very low level (a good feature to prevent accidentally blasting away one's speakers or ears). However, that low gain setting in insufficient for use as a basic amp. So I need to manually turn up the volume all the way every time I turn on the amp to use it. That's a little bit of a pain - but it gets much worse if I want to use 7 of the amps (bi-amping each speaker) in a home theater system (it would require running around the room and manually turning up 7 amps each time). I emailed the distributor, Shenzhen Audio, asking if this feature could be defeated, so the amp remains at the last set level, and they answered no (at least not without modifying the unit, if that is feasible).
So this unit really works best as a 2 channel integrated amp. With banana plugs or VERY careful use of bare wire.
First, the speaker binding posts on the back are reduced size. This was a necessity because of the small size of the case. However, it's dangerously easy to short out the speaker connectors with normal size spades or bare wire. Insulated banana connectors are probably the safest connection to use - though they are not my favorite. The electronics could be put in a larger custom cabinet with standard size binding posts - but that defeats the point of buying a finished amp (and the finishing on this amp is quite nice).
Second, the amp is really set up to be used as an integrated amp rather than a standalone basic amp. It has two inputs, front and back, which are switchable (a nice feature for an integrated amp). However, I want to use it as a basic amp with my HTPC analog output acting as preamp. I also want to turn it off when not in use (I'm pretty careful about minimizing unnecessary electric power usage - though I realize the 3116 draws only about a half watt when turned on but not in use, I'd rather save that power).
When the amp is turned off, and then turned back on, the volume is automatically reduced to a very low level (a good feature to prevent accidentally blasting away one's speakers or ears). However, that low gain setting in insufficient for use as a basic amp. So I need to manually turn up the volume all the way every time I turn on the amp to use it. That's a little bit of a pain - but it gets much worse if I want to use 7 of the amps (bi-amping each speaker) in a home theater system (it would require running around the room and manually turning up 7 amps each time). I emailed the distributor, Shenzhen Audio, asking if this feature could be defeated, so the amp remains at the last set level, and they answered no (at least not without modifying the unit, if that is feasible).
So this unit really works best as a 2 channel integrated amp. With banana plugs or VERY careful use of bare wire.
Les, thank you very much for your ongoing reviews.
Quick question: what's the best scenario to use with those T-amps? Set full volume on pre-amp (say iPhone, computer or actual pre-amp) and use the volume rotary on the T-amp for actual output, or set the t-amp full volume and use the pre-amp (again, iPhone, computer, actual pre-amp) to manually set the listening volume?
Quick question: what's the best scenario to use with those T-amps? Set full volume on pre-amp (say iPhone, computer or actual pre-amp) and use the volume rotary on the T-amp for actual output, or set the t-amp full volume and use the pre-amp (again, iPhone, computer, actual pre-amp) to manually set the listening volume?
Les I also want to thank you very much. I was just about to order one of these amps when I read your latest post. I also planned to use them in a bi-amped HT system driven from our HTPC, although I only need 6 channels total.
What a bloody shame on the volume issue! I guess their market is much more for standalone use than in a multi-amped system so I can understand their adding that 'Feature'.
I thought I had finally found THE amp that would work well and at it's price is a good value for fully assembled in a case with supply. So back to the drawing board!
I am looking for high SQ, so without doing lots of mods that my 73 year old hands and eyes are no longer good at I'm not sure what the best option now is. Some have posted that the green Audiobah board is one of the best unmodded. There are also the HiAmplifier boards Ultimate V1 TPA3116 Class D Stereo Power Amplifier Board w Bootstrap Caps | eBay They are certainly a lot pricier than any of the other bare boards and there has been little talk about them on any of the 3116 forums.
My preference would be a packaged amp such as the SMSL60 but I could install in a case if needed.
Any suggestions would certainly be appreciated.
Thanks,
Rod
What a bloody shame on the volume issue! I guess their market is much more for standalone use than in a multi-amped system so I can understand their adding that 'Feature'.
I thought I had finally found THE amp that would work well and at it's price is a good value for fully assembled in a case with supply. So back to the drawing board!
I am looking for high SQ, so without doing lots of mods that my 73 year old hands and eyes are no longer good at I'm not sure what the best option now is. Some have posted that the green Audiobah board is one of the best unmodded. There are also the HiAmplifier boards Ultimate V1 TPA3116 Class D Stereo Power Amplifier Board w Bootstrap Caps | eBay They are certainly a lot pricier than any of the other bare boards and there has been little talk about them on any of the 3116 forums.
My preference would be a packaged amp such as the SMSL60 but I could install in a case if needed.
Any suggestions would certainly be appreciated.
Thanks,
Rod
I don't know about FCC certification on this amp but it is not CE certified. CE logo on it is China export logo not Conformité Européenne.
5A6 diodes? Maybe inputcapacitors for DCblocking aren't necessary? I mean these seem to block DC towards source too, not from source?
Rod, you might check the HIFI 2.0 amps - I've got a couple, and I must say that they sound good - I didn't even feel the need to try any mods on them:
New Silver HiFi 2 0 Stereo Output Digital Power Amplifier TPA3116 50WX2 | eBay
You get a cased amp, ready to use - and, like I said, the sound quality is really OK for my ears 🙂
Even if you don't like it, at that price you haven't lost much...
It's not FCC qualified either. The FCC logo is a Chinese lookalike.
Or it's just a fake. The FCC logo holds no legal obligations. Anyone can smack one on to any device they like without any consequences. You cannot however put a fake FCC ID# on your device. The FCC ID# is the only thing that holds any legal obligation.
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the price is really good!
what are the electros between the bigger film capacitors and the chip/heatsink for?
so they tried to get that as close as possible towards the 'vcc-pins'?
too bad that they didn't place them left and right of the chip.
instead they could put the pins of the signal input right in front the input pins of the chip.
i would have tried to place the caps you use for signal input to place right above the other pin, which is closer to the chip.
If the input signal has already passed the input capacitors it's not that subjective to noise being differential. Also remember that the GVDD pin annoyingly placed in the center of the chip also has to be decoupled by at least 1µF. 2.2µF could also be used if it means you can buy bulk and thereby save money.
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