Wayne has previously measured these Silmics, and I have always trusted
his measurements, which put them on a par with Polypropylene for the
parameters of interest, specifically the resistance and distortion.
But since I am sitting in front of lots of expensive equipment, I made the
following test using my AP for performance in the kind of circuit I would
use them for, which is simply coupling.
I tested a 10 uF Silmic compared to a nice brand of PP driven by 600
ohms at 6 volts over a range of frequencies. The PP bottomed out at
0.04 ohms and the Silmic at 0.40 ohms
I then tested it for distortion when used as a coupling cap into 10 Kohm
at various audio frequencies with the same 6 volts. Whatever distortion
there was was below the system residual. Looking at the distortion
waveform with an averaging scope, nothing. With a spectrum analyzer,
only noise. I tested this with a bias voltage and not, no difference.
I further tested the Silmic under higher current conditions, 10 mA rms,
and they started to offer some distortion, bias dependent, which was
in the .002% range. The PP was better, but both were near the noise
residual of my setup.
You are of course free to find a better capacitor (or worse, if you like),
but I don't see a reason to stop using the Silmics.
This bottom dweller bought the boards, the sinks and all the components separately just a week ago. Then the kit comes out and I didn't really miss anything other than that bottom dweller price.
Sometimes, you just have to throw money at stuff until it either gives up or breaks you.
Where I would have saved a bit of time and money? If there was a current BOM in one spot. A sticky perhaps, with absolutely nothing else in it but those updates. Especially with regard to a specific min-max heat sink parameters.
Sometimes, you just have to throw money at stuff until it either gives up or breaks you.
Where I would have saved a bit of time and money? If there was a current BOM in one spot. A sticky perhaps, with absolutely nothing else in it but those updates. Especially with regard to a specific min-max heat sink parameters.
Running ACA on 36V?
Hello,
I'm wondering what the input voltage range is for the ACA? I'd like to use this as a portable amp, and I have a 2.7Ah 36V lithium ion battery that I would use.
If this voltage is too high, other suggestions are welcome!
Graeme
Hello,
I'm wondering what the input voltage range is for the ACA? I'd like to use this as a portable amp, and I have a 2.7Ah 36V lithium ion battery that I would use.
If this voltage is too high, other suggestions are welcome!
Graeme
Was this the 25V version you tested. The very small one (4 x 10 mm)?
When I look back I made a measurement on a 22uF / 50V Silmic II which is physical larger and this one had much lower serial resistance. So maybe size matters here?
I did this measurement for a friend (picture attached). When he watched the results for the small 10uF/25V he suggested that I had got fake Silmics II.....but hopefully not so.....I measured some of the other (I got 10) with same result. I also tried to use different current for the measurement. But one thing is serial resistance another is distortion.
I need a digital scope which can perform FFT analysis so I can measure distortion. It will also require a very clean sinus generator......
Another thing that was a bit strange is that it only measure about 7 uF at 10k Hz but about 9 uF at 100 Hz. Maybe this is caused by the relative large serial resisstance I measued at 10 kHz.
Attachments
Last edited:
I measued the physical size of the 10uF / 25V Silmic using a caliber. They are 5 x 11 mm. I can see that Mouser Electronics has the 10uF / 25V in both 5 mm and 6.3 mm diameter. This could mean something?
I have attached a link to the data sheet:
https://www.mouser.dk/ds/2/129/rfs_e-606.pdf
The 6.3 x 11 has higher mA rating than the 5 x 11 mA version........the 6.3 x 11 might also have lower ESR. But the 50V version could be better......
https://www.mouser.dk/ds/2/129/rfs_e-606.pdf
The 6.3 x 11 has higher mA rating than the 5 x 11 mA version........the 6.3 x 11 might also have lower ESR. But the 50V version could be better......
considering that ACA is having 10K-ish Rin , I wouldn't recommend any bufferless pot there , if one needs best possible results
In case of insisting on dumb pot , it can't be higher than 1K in value , so it is then up to sources (preceding pot) to have some cojones , able to drive it properly
2.7Ah is probably enough to feed some preamp stage , not amp working in Class A
besides , if you even think of doubling rail voltage , simply build amp which is made bigger from the start
conclusion ....... don't be so much of a cheapskate ......
if you look at pictures of M2 , DEF amp and some others , you'll see that Pa is clever chap ...... using smallest Silmics possible .... he also bought them in fridge box size quantity , so cheap that size became irrelevant ..... one toothpick price/piece
so , they simply ought to sound good
anyway , either believe fact that he's using them , further believe in his explanation how that's possible .... and use your brain power to think of some things more important for amps construction , than type of caps is ...
(and yes , silmic "issue" is nothing else than cluttering the thread)
I belive that the Silmics Pa has are good....but I may have got bad ones from DigiKey. I think it is good practice to test the components you get. I like to have some confidence in the components I put into the amp......and I don't have that for the 10uF (5 x 11 mm) Silmics I got. They must show better results at 10 kHz.
Sorry to crash the technical discussion. But plans to purchase the kit were foiled by the quick sell out AND I have a question(s).
The "new" ACA is no longer two physically seperate mono-blocks. Right? The mono blocks are now in one case. Correct?
So if, when in stock, I order 1 parts kit and 1 case (which assume is the complete kit for $278) I'll get everything I need to make this wonderful little stereo amplification system. Right?
PS: I'm hopeful of ordering this kit in April.
The "new" ACA is no longer two physically seperate mono-blocks. Right? The mono blocks are now in one case. Correct?
So if, when in stock, I order 1 parts kit and 1 case (which assume is the complete kit for $278) I'll get everything I need to make this wonderful little stereo amplification system. Right?
PS: I'm hopeful of ordering this kit in April.
you'll need not just a pot , you'll need buffer after it
buy ACA ,make it , then make B1 , any iteration of it
I already found the B1 on my own, but thanks anyway. What I réally want is an ACA with an integrated B1 (or something like it). Just one box, just one knob. I don't know if there's enough room in the chassis and of course such a kit would me more expensive, but it's what I would love to buy if it was available.
Don't let them fool you - Size always matters
😛
I was testing part # RFS-35V100ME3#5, Origin Thailand. This has been
on my shelf for several years, and I understand from Wayne that new
production is from China. I asked him to see about testing the current
ones to confirm performance.
Could be another example of valuable old parts that I have a hoard of....
OTOH our tests could easily be apples and oranges, as I only have a
vague notion about your conditions. Certainly I can come up with
scenarios where the Silmics will behave badly.
Off topic:
Originally Posted by Zen Mod
you'll need not just a pot , you'll need buffer after it
buy ACA ,make it , then make B1 , any iteration of it
I already found the B1 on my own, but thanks anyway. What I réally want is an ACA with an integrated B1 (or something like it). Just one box, just one knob. I don't know if there's enough room in the chassis and of course such a kit would me more expensive, but it's what I would love to buy if it was available.
Mr Pass, is it possible? 🙂
Originally Posted by Zen Mod
you'll need not just a pot , you'll need buffer after it
buy ACA ,make it , then make B1 , any iteration of it
I already found the B1 on my own, but thanks anyway. What I réally want is an ACA with an integrated B1 (or something like it). Just one box, just one knob. I don't know if there's enough room in the chassis and of course such a kit would me more expensive, but it's what I would love to buy if it was available.
Mr Pass, is it possible? 🙂
I think papa would reply pretty much the same as Zen Mod as to the requirement for a buffer for optimal results, and I think you've answered your own question: possible? - of course, but at just exactly what cost.
I use a Hioki 3522 LCR tester with Kelvin cables. I tested all 10 capacitors I have at 10 kHz. They all show the same figures.....more or less. Cs = 7 uF, D = 1, Ø = - 45 degree, Rs = 2.2 Ohm.
Then when I take my Jensen 10uF pure Alu foil capacitor it shows: Cs = 11 uF, D = 0.008, Ø = -89.5 degree, Rs = 12 mOhm.
I can change voltage, current etc...but no signigicant change when I does that.
At DigiKey manufacture says: Elna America .....is that the same as China? 🙂 ....maybe in a few years....
I get the ACA kit soon. There are included some 10uF Elna also. I will test them......and see....
I just observed that the 10uF Elna I have is this: # 604-1050-ND taken from the FirstWatt homepage in the article about the ACA. There is a part list with DigiKey numbers. So yours are 10 uF / 35V and the ones I have are 10 uF / 25 V. So it is not the same. Interesting what comes in the kit.......The 35V is this one: #604-1061-ND
My error. I tested the 25V part, but I pulled the number off a box on the
shelf of 35V parts. Next year when I have some more time I'll test those
too.
😀
Idealy total distorion of amplifier, in this case ACA, should be evaluated, not separate part out of context. Swaping caps, measuring/listening, that should be fun...