Thanks, Cal
Thanks, really all thanks should go to poster "2 picoDumbs" for explaining the issue, outlining how to test for it, and proving an alternative part. I just followed instructions and then updated the build thread...
F4 Mouser BOM
Here is mine, as a XLS-export (you will have to copy-paste every list-item) for a starter...
Also, I kept the required number of a part (and did not take the sometimes substantial price-reductions for more parts...)
CAUTION:
Be aware that this BOM most probably is not complete, and that, as I am still in my beginner-phase, it is error-prone, too.
To complete the list of self-complains, I haven't even started to build it, so I haven't been able to filter out missing or wrong parts...
HTH
david
(PS: maybe there is a hidden error, and maybe someone finds it—I'd gladly take notice of it 🙂 )
Here is mine, as a XLS-export (you will have to copy-paste every list-item) for a starter...
Also, I kept the required number of a part (and did not take the sometimes substantial price-reductions for more parts...)
CAUTION:
Be aware that this BOM most probably is not complete, and that, as I am still in my beginner-phase, it is error-prone, too.
To complete the list of self-complains, I haven't even started to build it, so I haven't been able to filter out missing or wrong parts...
HTH
david
(PS: maybe there is a hidden error, and maybe someone finds it—I'd gladly take notice of it 🙂 )
Please get the correct TL431. It should have a minimum current requirement of less than 300 uA and a ref viltage of 2.5V. Both these figures are quickly seen in the datasheet.
In case you want to cross-reference, here's mine: A guide to building the Pass F4 amplifier.
Note that this has the original shunt regulator listef. I'd recommend getting the one I linked a few posts back instead.
Note that this has the original shunt regulator listef. I'd recommend getting the one I linked a few posts back instead.
So this:
NCP431ACLPRAG ON Semiconductor | Mouser Italia
Instead of this:
TL431BQLPR Texas Instruments | Mouser Italia
Right? 🙂
Cal’s BOM motivated me to make a quick&dirty crosscheck of mine, and I marked several items with a „?“—notably the r1 r2 (rn70 resistors, they‘re very big) as well as r16 - r22 and d1 d2...
that's what cal says...
I go this way, too.
(PS: r1 r2 from my mouser-project definitely are too big, the wire's too thick to go through 🙄 )
Definitely. I'm listening to mine right now and they just sound spectacular. No modifications needed, just a drop in replacement.
And watch the Bourns-trimmers—I got the ones that are side-ways (instead of the vertical one...)
Min Shunt Current
How do i find min shunt current for my TL431BVLPRAG
https://eu.mouser.com/ProductDetail...w5vAhB7symQ==&countrycode=DE¤cycode=EUR
How do i find min shunt current for my TL431BVLPRAG
https://eu.mouser.com/ProductDetail...w5vAhB7symQ==&countrycode=DE¤cycode=EUR
Open the data sheet in the link.
Under 'RECOMMENDED OPERATING CONDITIONS'
Cathode Current IK 1.0mA
Under 'RECOMMENDED OPERATING CONDITIONS'
Cathode Current IK 1.0mA
Thanks!!!
If my amp bias perfect and off-set is perfect will i gain anything by changing the TL431 to a lower shunt current version?
Better PSRR
More stable bias and dc offset
Potentially quite a bit better sounding.
More stable bias and dc offset
Potentially quite a bit better sounding.
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Unfortunately that fact does not tell you if the 431 is working at spec. My build was the same, but was still under the min operating current of the 431. I thought it sounded good, but it is clear I had a lot of extra distortion. Replacing it was revolutionary.
You should just measure and see for yourself. Copying from 2PD's instructions with slight edits:
~~~~~
First measure voltage drop across 10k resistor R6 or R7. [Ideally this will be 13V or higher, often, however, it'll be around 12V.]
This will tell you total current. E.g. 12V/10k = 1.2mA
Now determine current in programming resistors = 2.5V/(P1+R9)
Let's assume P1 + R9 = 10k
So current would 2.5V/10k = 0.25mA
So cathode current would be 1.2 - 0.25 = 0.95mA. [That would be bad. Close doesn't cut it, must be over the minimum operating current. Replace with alternative part.]
~~~~~