Have you read this white paper? Section 4.1 goes over the distortion performance of the inductors.
https://www.ti.com/lit/an/slaa701a/slaa701a.pdf
It isn't just the thermal or amperage capacity of the inductor but also how linear it is. I've seen some I(A) curves that are pretty curvy. As far as "limiting performance" goes, TI has another white paper that shows that using higher-performance inductors, and implementing PFFB, both separately reduce distortion but also have a complementary effect. The distortion reduction of PFFB with better inductors, though, is somewhat reduced since there is less trash to clean up, so to speak.
Note: In Figure 22, I think they swap the colours for the MA5172-AE and MA5173-AE (I suspect that the MA5172-AE should be red, not black).
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Thanks for the link - no I have not read that WP yet.
Here is the datasheet for the SER series inductors. The design is very similar to Wurth with flat copper windings and shielded ferrite core. Here is the datasheet:
https://www.mouser.com/datasheet/2/597/ser2900-270685.pdf
In it, there is a plot of change on inductance vs current, and for the SER2915-103, the inductance is flat (very linear) from 0 to 10A and curves down by 10% from 10A to 20A. If you pick the SER2918-103, it is flat through 20A.
Here is the plot of inductance vs current from the datasheet. I am pretty happy with how linear it is. I had spec’d the SER2918 originally but ran into supply chain issues which is why I went with 2915. I think the Wurth equivalent may use the same footprints.
Here is the datasheet for the SER series inductors. The design is very similar to Wurth with flat copper windings and shielded ferrite core. Here is the datasheet:
https://www.mouser.com/datasheet/2/597/ser2900-270685.pdf
In it, there is a plot of change on inductance vs current, and for the SER2915-103, the inductance is flat (very linear) from 0 to 10A and curves down by 10% from 10A to 20A. If you pick the SER2918-103, it is flat through 20A.
Here is the plot of inductance vs current from the datasheet. I am pretty happy with how linear it is. I had spec’d the SER2918 originally but ran into supply chain issues which is why I went with 2915. I think the Wurth equivalent may use the same footprints.
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Thanks for the detailed response.
The high-performance Wurth inductors TI tested and showed in that WP are practically flat to 20 A, much like the 2918H.
https://www.we-online.de/katalog/datasheet/7443630700.pdf
https://www.mouser.ca/datasheet/2/445/7443641000-1721715.pdf
Again, seems to be a typo by TI... I think 7443641000 instead of 74436301000.
The high-performance Wurth inductors TI tested and showed in that WP are practically flat to 20 A, much like the 2918H.
https://www.we-online.de/katalog/datasheet/7443630700.pdf
https://www.mouser.ca/datasheet/2/445/7443641000-1721715.pdf
Again, seems to be a typo by TI... I think 7443641000 instead of 74436301000.
Thanks, there is a GB2 thread and we need 3 more in order to go to production. These are professionally assembled in USA using genuine Mouser BOM.
XRK RTR TPA3255 Reference class D Amp GB2
XRK RTR TPA3255 Reference class D Amp GB2
Hi Redjr,
Thanks for the update and glad your amp is still making great music. I have been listening to mine for the past week also and it’s sounding great too.
I am enjoying "Hysteria (Remastered 2017)" by Def Leppard on Amazon Music. https://music.amazon.com/albums/B07...0792TVCTV&ref=dm_sh_NfDyOT0w0rp3kEcG9atfmSNhH
I am wondering if anyone has tried this amp with a big linear supply - like a 400VA 35v toroidal with say, 40,000uF of filtering rail caps? I wonder if it will have more bass authority as we sometimes see happen when a linear PSU is used on Class AB amp.
Btw, if you want a cool track to test your amp/speakers range and clarity, here is a good one.
Check out "Chocolate Chip Trip" by TOOL on Amazon Music. https://music.amazon.com/albums/B07...07WL7NFDM&ref=dm_sh_QEBybRts3AYzA5H5Wj9AUBBrm
Thanks for the update and glad your amp is still making great music. I have been listening to mine for the past week also and it’s sounding great too.
I am enjoying "Hysteria (Remastered 2017)" by Def Leppard on Amazon Music. https://music.amazon.com/albums/B07...0792TVCTV&ref=dm_sh_NfDyOT0w0rp3kEcG9atfmSNhH
I am wondering if anyone has tried this amp with a big linear supply - like a 400VA 35v toroidal with say, 40,000uF of filtering rail caps? I wonder if it will have more bass authority as we sometimes see happen when a linear PSU is used on Class AB amp.
Btw, if you want a cool track to test your amp/speakers range and clarity, here is a good one.
Check out "Chocolate Chip Trip" by TOOL on Amazon Music. https://music.amazon.com/albums/B07...07WL7NFDM&ref=dm_sh_QEBybRts3AYzA5H5Wj9AUBBrm
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Hi X,
A silly question but the SMPS800RE is a differential output supply, they also offer a single output version. Which one would you recommend using with your TPA3255 reference amp and why? I’ve tried googling and haven’t really found anything definitive on the pros and cons. Mainly the results refer to SE vs Diff line inputs rather than power supply specifics.
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Hi X. I don't have your amp unfortunately but as you know I just built a version of your transient perfect monitors and I run a hefty unreg psu and a 3e 3255.
525VA 35v toroid gives me 49v and I use 2200uf x 14 cap bank all bypassed with 1uf x 14.
I only tried a MW smps for a short time but u could hear the pwm. Not through the speakers but just from the psu itself. I prefer the simplicity and reliability of using trafo/rectifier/ cap bank. I cant say of its performance against an SMPS...it 'just works'!
Yes, I must have the single rail version.
I have recently tested the Cresnet (MicroAudio) SMPS630-SO and it works superbly. It has built in regulated auxiliary +12v, +3.3v always on. +/-12v switched. Remote turn on with delay and remote open collector turn off output signal for SSR’s. Does not have startup hiccup and can use extra output capacitance even. Very quiet. I can highly recommend these supplies. You may need to request a custom 52v model but 48v off the shelf can work fine. The output is not adjustable.
Your experience is similar to Vunce, who recently tried a big linear supply with his TPA3255 and he said it sounds superb. Absolutely silent with no music playing and ear pressed to speaker cone. Here it is with two massive 22,000uF caps with screw connectors and an LT4320 active bridge:
Hi Folks,
It has recently come to my attention that the RTR prebuilt amp boards were assembled with redundant input caps. Only one of the other was needed and we have nice Selma Silmic II 10uF input caps AND 10uF 16v X7Rs installed by accident on the bottom side. You may or may not notice the sound improvement by removing them. But the Elna’s are probably superior to 1206 X7R MLCCs. Vunce tried removing them and he said it was noticeably better.
Anyhow, sorry about the mixup. They are easy to remove - the 4 big caps on the bottom side. Please see photo. On the other hand, the sound quality and measurements were excellent despite this. Don’t worry about the note on R221 except that it should be 22k.
I have already made a note to DNP (do not populate) these caps on the GB2 going on now.
It has recently come to my attention that the RTR prebuilt amp boards were assembled with redundant input caps. Only one of the other was needed and we have nice Selma Silmic II 10uF input caps AND 10uF 16v X7Rs installed by accident on the bottom side. You may or may not notice the sound improvement by removing them. But the Elna’s are probably superior to 1206 X7R MLCCs. Vunce tried removing them and he said it was noticeably better.
Anyhow, sorry about the mixup. They are easy to remove - the 4 big caps on the bottom side. Please see photo. On the other hand, the sound quality and measurements were excellent despite this. Don’t worry about the note on R221 except that it should be 22k.
I have already made a note to DNP (do not populate) these caps on the GB2 going on now.
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I measured the background noise floor of this amp with the new Micro-Audio SMPS630-SO power supply. It is very quiet amp combo - almost perfect. Using the new BTSB v1.2P with a balanced line input and no music playing, this is what the FFT on a 10ohm load looks like:
Setup:
Setup:
Very good - what's your listening impressions of the Micro-Audio SMPS630-SO vs the Aliexpress 800w LED PSU?
The Micro-Audio is designed for audio and so has a lot of built in amenities like always on linear regulated 12v for your accessories or preamp. +/-15v linear regulated that is turned on with main power, and 3.3v or 5v auxiliary that is turned on with main power. There is a remote enable switch that lets you power it up with a 2 second delay. But mostly the sound quality seems to have more weight in the bass department. As you can see from the data, it is very quiet at the mains frequency and it is quieter in the highs too. The Micro-Audio doesn’t have an issue driving a huge cap bank either and adding 40,000 uF between the PSU and amp is something possible (and PCB is provided) with this PSU. Overall, a superior solution. Best of all, you are dealing with Sami, the company owner and designer. He is very responsive and goes out of his way to provide value added customizations and will tailor the SMPS to your specific needs if the request is reasonable. Perhaps one of the best customer service experiences in audio that I have seen.