sorry for yet another nube question as im just a humble speaker builder and you guys are way ahead of my ability so again thank you all for your posts as im learning a lot but has anyone had a chance to implement the PFFB option in their design yet?
is this a easy mod for existing 3251 boards?
have ti used this option on their 3255 evaluation boards?
is this a easy mod for existing 3251 boards?
have ti used this option on their 3255 evaluation boards?
5th element i just checked out your site the 2 skinned bendy mdf on your FSTNT1 is genius id seen this mdf before and thought it was to weak but now am convinced of what a great idea it is also your speaker looks like b and w and kef had a affair and had a love child wow what a fantastic build i will be using many of your idea's in the future great work
It's implemented in both the 3251 and 3255 EVM but not stuffed/equipped. Will have it on the new board as well. (Bottomside)
I rearranged the ouput/decoupling stage a bit to have better heatflow.
TPA3255 on 360customs.de
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Well I have although that's in the 3251 thread
Many thanks for your kind words on the website and the contents within. At some point I will be uploading my TPA3251 builds etc with PFFB
There's also an update planned for the FSTNT1, the update is largely written it just needs a proof read
doctormord,
Is there a particular reason you haven't stuffed the PFFB option on your development boards or have you actually tested that and don't use it for some reason? I've been following you for some time and love your designs and what research you've done with a few others on the 3251 thread. Are you only going to sell completed boards or are you also going to sell your unstuffed boards? In the 3251 thread you had two versions of the amp, one like I see here that is very small and a larger board, are you still working with both layouts?
5th Element,
Nice design work on your website your building. I didn't at first realize that the speaker pictures were active links. I have to go back now and read your website to see what you've done. Nice woodwork.
Steven
Is there a particular reason you haven't stuffed the PFFB option on your development boards or have you actually tested that and don't use it for some reason? I've been following you for some time and love your designs and what research you've done with a few others on the 3251 thread. Are you only going to sell completed boards or are you also going to sell your unstuffed boards? In the 3251 thread you had two versions of the amp, one like I see here that is very small and a larger board, are you still working with both layouts?
5th Element,
Nice design work on your website your building. I didn't at first realize that the speaker pictures were active links. I have to go back now and read your website to see what you've done. Nice woodwork.
Steven
Hi Steven,
when i made the previous boards, PFFB wasn't an option, as no application note existed. The goal was to get somewhere near the THD performance of the EVM, which, to my/our surprise, isn't that easy in detail. Output inductors have the biggest influence and we tested a lot of different types/brands. While still performing nice with good results, the THD measurements where ~1/2 decade higher than on the EVM. (Still under 0.02% for up to 100W/ch)
The red board is performing a bit better then the blue one, so a pretty solid build.
From the comparison:
The red is on the same level as the blue board equipped with a 3255 and huge VER2923 inductors.
But this might be a result of a non-optimal (unconfirmed) PSRR problem of the chips. 5th element did some investigation in this direction month ago, if i remember correctly.
(As always, this is still a fun/education project, so no complete kits nor prebuild boards. But i still have 1-2 bare red boards avail if you want to stuff it on your own. There are actually 5 red amplifiers build by members of the forum, and some blue ones as well.)
when i made the previous boards, PFFB wasn't an option, as no application note existed. The goal was to get somewhere near the THD performance of the EVM, which, to my/our surprise, isn't that easy in detail. Output inductors have the biggest influence and we tested a lot of different types/brands. While still performing nice with good results, the THD measurements where ~1/2 decade higher than on the EVM. (Still under 0.02% for up to 100W/ch)
The red board is performing a bit better then the blue one, so a pretty solid build.
From the comparison:
The red is on the same level as the blue board equipped with a 3255 and huge VER2923 inductors.
But this might be a result of a non-optimal (unconfirmed) PSRR problem of the chips. 5th element did some investigation in this direction month ago, if i remember correctly.
(As always, this is still a fun/education project, so no complete kits nor prebuild boards. But i still have 1-2 bare red boards avail if you want to stuff it on your own. There are actually 5 red amplifiers build by members of the forum, and some blue ones as well.)
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Dr. I would take that to mean that you would implement the PFFB on any future builds as that makes a definite improvement. Perhaps with this in place the need for the most expensive and large inductors won't be such an issue. I am only looking for the chip to top out at 100W @8 ohms so that may save some money not needing the best coils to keep the distortion down. Thanks for the answers.
Maybe you missed the point, where i posted that PFFB is implemented on the new board.
Source: http://www.diyaudio.com/forums/clas...-diy-discussion-design-etc-5.html#post4859012
The inductors used on the new board are "cheaper" than the Coilcraft, currently at ~$4/pcs when ordering 25pcs.
Regards.
Source: http://www.diyaudio.com/forums/clas...-diy-discussion-design-etc-5.html#post4859012
The inductors used on the new board are "cheaper" than the Coilcraft, currently at ~$4/pcs when ordering 25pcs.
Regards.
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DR., no I noticed that you said it was there on the board but not stuffed. I wondered if you had decided for some reason not to use that part of the circuit. It sounds like you are using it to lower the cost of the coils and improve the distortion numbers at the same time. Thanks as always for the information and your help.
Well then there's a misunderstanding.
The TI EVMs (3251, 3255) have the PFFB option on board but not stuffed, my red and blue board don't have/had the PFFB option implemented, as there where no application note from TI to show how to proper use it. The new board will have the PFFB option on board, but also not stuffed by default. (As this needs proper measurements first)
To have the best possible start, i'd choosen thos beefy Wurth inductors for now.
Regards.
The TI EVMs (3251, 3255) have the PFFB option on board but not stuffed, my red and blue board don't have/had the PFFB option implemented, as there where no application note from TI to show how to proper use it. The new board will have the PFFB option on board, but also not stuffed by default. (As this needs proper measurements first)
To have the best possible start, i'd choosen thos beefy Wurth inductors for now.
Regards.
Yes, you may check the application note how to do.
http://www.ti.com/lit/an/slaa702/slaa702.pdf
http://www.ti.com/lit/an/slaa702/slaa702.pdf
I've ordered pcbs from the fab. When arrived here, i will stuff 1-2 boards for measurements and testing. (I.e. with the new LLC power supply a friend did developed.)
So if that worked out fine, i have some spare boards left from the first batch for anyone who will solder an amp on their own.
When arrived here, i will stuff 1-2 boards for measurements and testing. (I.e. with the new LLC power supply a friend did developed.)So if that worked out fine, i have some spare boards left from the first batch for anyone who will solder an amp on their own.