Is not better inductor.
Really better is Wurth 7443630700 and Codaca CSCF2014
That's why I included the plots and calculations. Yes, they are based on general assumptions, but the trends still apply in case others want to try inductors themselves.
Thank you for the suggestion to try the inductors. They did make a significant improvement. The best way to describe the improvement is similar to improving the headroom of an amplifier--basically extending power output without increasing distortion, so the audible effect is greater dynamic range and greater depth to the soundstage.
I love the soundtrack to the Spanish movie "Habla con ella" ("Talk to Her"), and Track 4, "La Mesita de Noche," really demonstrated that. There is a drum beat that symbolizes a heartbeat that resonates in the background of the soundstage with a guitar in the foreground and orchestra behind.
I also played "Dream Within a Dream" on vinyl from the 80's German group Propaganda where the conga drums remained distinct as more instruments including synths are added to the mix. I also spun a remastered LP of The Rolling Stones "Let It Bleed," and it rocked my listening room. I enjoyed better separation of instruments and vocals.
I did not photograph the underside of the PCB since it just has through-hole leads poking through. I should mention that in installing any new components inside the Aiyima amps, one should trim the through-hole leads sufficiently enough to keep anything from shorting. There isn't much room underneath.
Unfortunately, I don't have the equipment to test Class D amps adequately, but my ears tell me that these were an improvement over the stock inductors. You won't get any argument from me regarding the Wurth and Codaca inductors. I am sure these are better than the Coilcraft MA5173 inductors with their greater linearity and current handling.
The Coilcraft inductors cost $24 USD, which was almost half of what I spent on the original Aiyima amp. The change of the inductors was a significant improvement as were the op amp upgrades. As I've said before, I am finished with spending any more money on this amp. As you've pointed out, the volume pot (presumably an Alps) and the constrictive space to upgrade the volume pot is a limit to how far one could go with this amp. Where I am at now with this amp is that it is better. I will find out how much better when I receive another one of these amps to modify for my friend in Brazil. I will do a side-by-side comparison with the stock unit in both my systems.
Compared to my higher performance amps, the Aiyima is still not as good. It still can have some of the Class D glare on more complex music and it isn't rock solid like a really well executed Class A amp, but for $50 USD, I would spend the extra money and invest a little soldering time to upgrade the wiring, touch up some of the solder joints in the signal path, and roll a few op amps. It is more quiet than my TI TPA3255EVM amp and sounds better. For a complete amp, I still contend that this is a bargain. If one wants a significantly higher level of Class D performance, then I would invest in some of the better DIY offerings out there or the Hypex Ncore amps (which I have not heard yet).
I hope the manufacturer has not started to skimp on components as sales have picked up. From what I've read on the TPA3255 amp, it appears that they've changed some of the electrolytic input caps.
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THanks anyway amigo. I have some of those Coilcraft in stock. I will try asap but I am not good in soldering.... I will share my opinion when it is done )
Many thanks for your effort )
This is an acute observation which is born out by measurements. I don't think the TI engineers would have taken this inductor if there were better ones on the market. In spite of what Mr Mordor may believe, I am only swayed by measurements and this one I did myself. There may be better ones out there, but please provide proof.
The Coilcraft inductors wire and leads are slightly larger in diameter than with the stock inductors, and the through-holes are somewhat tight, so you will need to use a good solder sucking tool and technique to thoroughly clear out the holes. Otherwise, it will be next to impossible to properly install the Coilcraft inductors.
You also have to be careful with your solder iron not to touch the adjacent components like the Epcos output filter caps. The space is very tight.
You also have to be careful with your solder iron not to touch the adjacent components like the Epcos output filter caps. The space is very tight.
THanks anyway amigo. I have some of those Coilcraft in stock. I will try asap but I am not good in soldering.... I will share my opinion when it is done )
Many thanks for your effort )
Hi Danny. Pity you are not a bit closer and I would happily do the soldering for you !!
I just wonder from these plots whether there wouldn’t be a change in the sound from changing the original 12.5uH inductors with 7uH inductors regardless of the brand of conductors used. Visually the Coilcraft cores look a bit more chunky and wire looks like a heavier grade so maybe less resistance but otherwise similar construction. Clearly these boards don’t have the physical space for the Wurth or other significantly different Inductors.
So from a construction point of view, ignoring the change in inductance value, how much better are the Coilcraft from the original Aiyima Inductors ?
I made an order for Wurth 7443630700 , Codaca CSCF2014 and nanocrystalline core
When I receive them I will take measurements.
I am preparing a PCB for these inductors.
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Hi bushellj,
You really need to understand the impedance vs. frequency response of your speakers to know whether changing the output filter inductance will have a positive effect or not. I chose the Coilcraft MA5173 based on the fact that the 7uH inductance appears to be a better match to my KEF LS50 speakers than the 12.5uH stock inductors. Here is a plot of the impedance vs. frequency response for the KEF LS50 speakers from Stereophile where I highlighted the 10-20kHz impedance dropping from 6 to 5.6 ohms:
My Klipsch Forte II speakers have an impedance of 10-12 ohms in the same range of 10-20kHz, which could result in an actual rise of high frequency content based on Texas Instruments' LC filter designer spreadsheet. That hump in the 8 ohm curve (black) between 10kHz and 90kHz is not desirable.
As vacuphile mentioned before, a 10uH inductor like the Coilcraft MA5172 will work for most speakers with 6-8 ohms nominal impedance, and a set of 4 will fit inside the Aiyima chassis.
My opinion is that Texas Instruments chose these Coilcraft inductors over others for their performance-cost. I believe these would be an improvement over the stock inductors given equal inductance values. I'll leave it up to you to determine if the improvement is worth the expense.
To drMordor's point, the Wurth and Codaca inductors are probably better than the Coilcraft MA517x inductors, but you would have a struggle neatly fitting those inside the Aiyima's compact enclosure.
If struggling to fit bigger coils, one could try to fit them upright.
Further, if soldering is hassle because of the tiny space and existing small leads/small board holes...
If there is enough room under the cover for say an extra cm, one could consider desoldering the existing coils and soldering on the new coils as extension to their legs small lugs / pins that would fit in the board's hole. That could help a lot adapting geometry with another, bigger coil, provided you have some extra space under the cover / verticaly. The coils could vibrate if these legs are too long, blu tack may help...
Looking at the board and tiny traces, and recommended PS, it seems clear that this small unit is not designed to deliver a lot of current / power vs what the ampchip could do. I have no clue, but would dount it is capable of more than 3A continous per channel, which equals to only 72W / 8R or 36W/4R... so not a lot but thenthe positive is playing with extra small legs etc. is probably not an issue as the traces / the amp doesn't deliver a lot of current. You wouldn't want to do what I just posted on a 1000W amp unless you want to creat an output fuse
Claude
Further, if soldering is hassle because of the tiny space and existing small leads/small board holes...
If there is enough room under the cover for say an extra cm, one could consider desoldering the existing coils and soldering on the new coils as extension to their legs small lugs / pins that would fit in the board's hole. That could help a lot adapting geometry with another, bigger coil, provided you have some extra space under the cover / verticaly. The coils could vibrate if these legs are too long, blu tack may help...
Looking at the board and tiny traces, and recommended PS, it seems clear that this small unit is not designed to deliver a lot of current / power vs what the ampchip could do. I have no clue, but would dount it is capable of more than 3A continous per channel, which equals to only 72W / 8R or 36W/4R... so not a lot but thenthe positive is playing with extra small legs etc. is probably not an issue as the traces / the amp doesn't deliver a lot of current. You wouldn't want to do what I just posted on a 1000W amp unless you want to creat an output fuse
Claude
The news to me was that the original inductors supplied with these amplifiers is 12.5uH which is clearly higher than what one would have expected and probably not the best match for a lot of speakers. So if you are going to change them for values that better match the speakers, you might as well use a quality brand. The cores clearly look bigger so won't saturate so quickly if of course you reach these levels.
My concern now that we are seeing more people purchase these Aiyima (and other brands selling the same product) amplifiers is that the components and there quality appear to be changing for cheaper brands !! I also not that the "new" Aiyima TPA3255 model is a completely different board inside and looks very much "cost reduced" - Different Pot (looks cheap), no sockets for the Op-Amps etc.
Do we know who is the original company that produces the Aiyima TPA325x products ? It was Tilear for the TPA3251 model as far as I was aware. The chinese produce masses of the these products with no branding, no manuals, no circuit diagrams etc. All sellers use the same photographs but users are clearly receiving different models - sometimes completely different boards.
James.
For those who would be interested to get the Aiyima TPA3251 without any issues; you can order it via Amazon, fast delivery ! (got mine in 4 days from USA to France)
it is more expensive than in China but you are sure to be delivered and good guarantee
Amazon.com: AIYIMA 175W +175W HiFi Mini Power Amplifier 2 Channel TPA3251 Digital Audio Amplifier NE5532 High Power Full Frequency Class D Amp Home Professional (Black): Home Audio & Theater
For the PSU, this is works really fine and good price (it is stable, I measured it in multi meters @ 35V / 6A exactly)
The same : fast delivery and good guarantee
FX-AUDIO Adaptateur Secteur Alimentation 100-240V vers 36V 6A - Audiophonics
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