Makes totally sense with this wiring.
(Btw. bass calculation were done as well, maybe you skipped reading.)
But yeah, back to topic. Irribeo is always right. 🙂
(Btw. bass calculation were done as well, maybe you skipped reading.)
But yeah, back to topic. Irribeo is always right. 🙂
🙂 yeah fun pic, a clean caps install in smsl enclosure could be better 🙂
Yes I read bass calculations, didn't want to forget that because all the sleepy posts about the other part. I once tried to calculate based on joule lounge discussion on this subject, that got me 2 times 3300uF, but don't recall 100% how I did that, not even if it was for mono or stereo 3116 if that matters, and know I probably made some errors, feel no urge to reread lounge discusion. Was ripple in it and French Citroen car look a like formula and some frequency psu output/chip, arrrg don't like it 🙂
Yes I read bass calculations, didn't want to forget that because all the sleepy posts about the other part. I once tried to calculate based on joule lounge discussion on this subject, that got me 2 times 3300uF, but don't recall 100% how I did that, not even if it was for mono or stereo 3116 if that matters, and know I probably made some errors, feel no urge to reread lounge discusion. Was ripple in it and French Citroen car look a like formula and some frequency psu output/chip, arrrg don't like it 🙂
Sounds legit. 😀
I recently put this calculation into simulation, especially for bass support - to have a significant (supporting) effect it needed 1.4 farads to holdup 100ms bass note, so, for me, this isn't working in practice. When using an SMPS with several kHz regulation bandwidth chances are good that the supply is compensating the voltage drop fast enough - for the case you don't use lots of ufarads at the amp.
Thanks guys, I think irribeo summed it up pretty good 😀. My takeway is:
When using smps on these boards, assuming correct Vdc rating: to improve the general quality of sound (clean, distortion free), the dc power caps are important, and it's about minimizing ESR. These caps function more like filters. To do that, use multiple caps in parallel if you can, because ESR is a fractional calculation of the number of caps. Throw an oscon or other polymer in the mix because they handle current at high frequency well with very low ESR.
There is a minimum capacitance that can be calculated, but there isn't really an upper limit. Low ESR is more important, and of coarse what will physically fit on board/enclosure. NOTE: some manufactures don't list ESR spec, so the impedance at 20c is roughly equivalent? I've seen reference to the physical dimensions being relevant to performance, try to keep your actual physical cap size (diameter) between 10-12.5 mm. Have some headroom in your capacitance, some people put ALOT of headroom in the capacitance because they think it will help with bass, but it takes a lot of uF and may be impractical.
Is that about right?
When using smps on these boards, assuming correct Vdc rating: to improve the general quality of sound (clean, distortion free), the dc power caps are important, and it's about minimizing ESR. These caps function more like filters. To do that, use multiple caps in parallel if you can, because ESR is a fractional calculation of the number of caps. Throw an oscon or other polymer in the mix because they handle current at high frequency well with very low ESR.
There is a minimum capacitance that can be calculated, but there isn't really an upper limit. Low ESR is more important, and of coarse what will physically fit on board/enclosure. NOTE: some manufactures don't list ESR spec, so the impedance at 20c is roughly equivalent? I've seen reference to the physical dimensions being relevant to performance, try to keep your actual physical cap size (diameter) between 10-12.5 mm. Have some headroom in your capacitance, some people put ALOT of headroom in the capacitance because they think it will help with bass, but it takes a lot of uF and may be impractical.
Is that about right?
Mostly, but this depends on your power supply. If it's a classic linear regulated transformer supply (100Hz/120Hz) you'll need to have this "big headroom" of "ompf" aka uF. But with switched supplies in the 100kHz+ range it isn't needed.
If a manufacturer don't list ESR, then skip em, you'll need to know. For the rest, irribeo summed it up right. Calculate your needed minimum capacitance, ESR and current to select the right caps.
Having headroom in capacitance is important due to aging, as capacitance decreases - also the ESR increases, which also is stated in the datasheet. You'll want to have some margin here as well.
Estimated life of caps can be taken from the datasheet as well. If a cap is rated for 1000h this is at maximum temperature and rated current. For every 10°C decrease of temperature the lifetime is doubled.
So 1000h @ 105°C becomes 2000h @ 95°C, 4000h @ 85°C etc.
Lifetime increases further for decreased applied working voltage and current.
For cost optimization, current handling capability of the selected caps can be relaxed if you consider that normal music isn't continous sinewave, but have a crest factor of ~6:1 - 8:1. So your average current demands are at this factor lower. Practical evaluation will tell.
The calculations made here are based on this:
http://www.ti.com/lit/an/sloa031/sloa031.pdf
Point 5.1 ff.
regards,
I don't see ESR rating for a lot of Napa/United Chemicon caps, aren't these considered very good? But it does have impedence rating, and from what i've read the figure is usually close to identical?
http://www.chemi-con.co.jp/cgi-bin/CAT_DB/SEARCH/cat_db_al.cgi?e=e&j=p&pdfname=kzh
http://www.chemi-con.co.jp/cgi-bin/CAT_DB/SEARCH/cat_db_al.cgi?e=e&j=p&pdfname=kzh
Yeah, you're right it's the "same" as ESR. Just make sure it's shown for 100kHz or higher. 120Hz rating is not what we are looking for.
Napa?? National Panasonic ?? Oh I know, Nippon typed on IPad/IPhone 🙂
(Pictured tda7492 has two electrolytics that are very expensive and I can only buy them at places I am certain to get fakes, but I would like to have those to test in some other non switching application, not being able to buy the expensive audio Jovials makes them mythecally good jeje )
(Pictured tda7492 has two electrolytics that are very expensive and I can only buy them at places I am certain to get fakes, but I would like to have those to test in some other non switching application, not being able to buy the expensive audio Jovials makes them mythecally good jeje )
Last edited:
napa - oops, yeah Nippon - I'm shopping U.S. car parts too... but I don't think an alternator is going to fit in there! 🙄
Last edited:
- Status
- Not open for further replies.