Forgive me if this has been covered here already, but there are many different grades of non-polar electrolytic caps. The ones proac uses are middle of the road and similar to others in that price point, being of same quality. Many say you can't really hear the quality of a parallel cap in a LP circuit compared to a series cap in a tweeter HP, but i beg to differ.
The problem is, if you want to replace that electrolytic with a film cap, you need to compensate for the series resistance of the electrolytic so the filter response behaves the same way as before. You may need to add 0.5 - 2 ohms in series so the target filter rolloff response is duplicated as manufacturer designed it to be. In most cases with the smaller 50V caps in a smaller speaker 1 Ohm @ 5W is about right and a good safe starting point. In some cases with very large value caps, I even add a very small parallel inductor of around 0.1-0.2 mH across the resistor to mimick the cap losses higher up in frequency. That is however in most cases being really picky and borderline OCD, but it can help duplicate the original behavior of the old cap if its age is really up there. Anyways, after the cap change you may notice a significant improvement in lower midbass precision and articulation.
The problem is, if you want to replace that electrolytic with a film cap, you need to compensate for the series resistance of the electrolytic so the filter response behaves the same way as before. You may need to add 0.5 - 2 ohms in series so the target filter rolloff response is duplicated as manufacturer designed it to be. In most cases with the smaller 50V caps in a smaller speaker 1 Ohm @ 5W is about right and a good safe starting point. In some cases with very large value caps, I even add a very small parallel inductor of around 0.1-0.2 mH across the resistor to mimick the cap losses higher up in frequency. That is however in most cases being really picky and borderline OCD, but it can help duplicate the original behavior of the old cap if its age is really up there. Anyways, after the cap change you may notice a significant improvement in lower midbass precision and articulation.
Funny as that is EXACTLY what I drew out in XSIM
the first pic is with a very small resistor in series with the cap.
the second pic is how it is originally without the small 0.1ohm resistor
it makes a slight bit more of a roll off high up on the woofers cross.
and yes I agree. You CAN hear a difference even in the woofer circuit
what do you think?
the first pic is with a very small resistor in series with the cap.
the second pic is how it is originally without the small 0.1ohm resistor
it makes a slight bit more of a roll off high up on the woofers cross.
and yes I agree. You CAN hear a difference even in the woofer circuit
what do you think?
I could measure the electrolytics as well with a really good meter to see the DCR
my meter for resistance doesn’t measure that low
my meter for resistance doesn’t measure that low
I doubt you will readily hear the effects of extra 0.1R in that circuit, but the sim does show a slight flattening of response with its presence. I would see how much it changes FR by further increasing series R to about 0.5 or even 1R. Predictably, further increasing series R will eventually make midbass FR climb further and create a midrange hump, transitioning closer to a 1st order LP response.
I believe you'll see a greater benefit in your specific example with less series R than trying to compensate for it after upgrading that cap to PP film. It's not a hard rule it will behave text book and sometimes it may be welcome if it does. Really depends on your taste and final goals.
I believe you'll see a greater benefit in your specific example with less series R than trying to compensate for it after upgrading that cap to PP film. It's not a hard rule it will behave text book and sometimes it may be welcome if it does. Really depends on your taste and final goals.
^^ Measuring ESR is not as simple as that.
Are you able to turn on phase for each way in Xsim?
Are you able to turn on phase for each way in Xsim?
It’s all under control gentlemen
lol
i called falcon acoutstics and the kind man will measure a 16uf 50v alcap for me to tell me the DCR.
Done
lol
i called falcon acoutstics and the kind man will measure a 16uf 50v alcap for me to tell me the DCR.
Done
A higher end LCR meter will measure more precise "static" ESR vs. frequency, but an accurate ESR measurement has to take into account the specific current and voltage swings across the cap in the circuit its operating. Loudspeakers are complex loads, not resistive. Thats why electrical phase measurements are important here.
He needs to measure DCR from about 50 to 5000 Hz to get a good idea of cap linearity. Measuring at just one frequency won't be enough if you plan on getting this audibly close, plus it still may be different enough to warrant your own measurements and/or manual tweaking to get it sounding the way you want.
There is always a way
once he tells me the DCR I will be able to simulate the capacitor almost perfectly
and it’s a great experiment to see the difference.
in the simulation there is a big difference in how the woofer roll off behaves compared to just a capacitor value change. Adding some series resistance rolls off the woofer much higher up close to the cross point.
let’s see if it make a sonic difference.
i can tell you one thing. The poly cap is better.
more to come.
this is super fun
once he tells me the DCR I will be able to simulate the capacitor almost perfectly
and it’s a great experiment to see the difference.
in the simulation there is a big difference in how the woofer roll off behaves compared to just a capacitor value change. Adding some series resistance rolls off the woofer much higher up close to the cross point.
let’s see if it make a sonic difference.
i can tell you one thing. The poly cap is better.
more to come.
this is super fun
i told him why I need the measurement.
he understands exactly what I want.
and has the equipment to do it.
hopefully by tomorrow I’ll have an answer for you guys.
then I can order some resistors and see what happens
This is seriously fun.
So here is another question please
I made another silly video since it’s much easier to explain this way.
are my observations correct in this video?
because i did add a 1uf capacitor on top of those separate caps in parallel to see what difference they had sonically.
the addition of 1uf to the 8.2uf cap added a touch of highs but I think more ‘ immediacy ‘ of the highs? Is that because there is a slight increase of efficiency to the teeeter?
and again when I added the 1uf cap to the 6.8uf cap it added more highs but they sounded ‘ smoother ‘ in nature. Is that because the efficiency was reduced slightly by the change?
much appreciated once more gentlemen!
So here is another question please
I made another silly video since it’s much easier to explain this way.
are my observations correct in this video?
because i did add a 1uf capacitor on top of those separate caps in parallel to see what difference they had sonically.
the addition of 1uf to the 8.2uf cap added a touch of highs but I think more ‘ immediacy ‘ of the highs? Is that because there is a slight increase of efficiency to the teeeter?
and again when I added the 1uf cap to the 6.8uf cap it added more highs but they sounded ‘ smoother ‘ in nature. Is that because the efficiency was reduced slightly by the change?
much appreciated once more gentlemen!
You're simply increasing cap coupling down lower in frequency and hence reducing impedance in that area. This is why it will sound slightly louder and fuller. It has nothing to do with efficiency. You are however shifting phase in that area as well, likely not to your advantage. 3rd order filter interaction of components can be complex.
Member
Joined 2019
Hi all,
Late to the party as usual.
I have a pair of DT8's, great speaker, but always room for a bit of fiddling!
Did this thread have any resolution (pun intended). ie. A new external crossover with schematic and recommended components (make, values etc.). Or did Stewart Tyler at ProAc get it right first time even with the obvious budget constraints?
Anyone?
These are hooked up to:
IBM Nuc running Roon
Fully balanced Cambridge 851D DAC
Advantage S2 Class A preamp, fully balanced
Advantage S150 fully balanced Class A power amp (2x150watts and capable of delivering 51 Amps (EEK!)). Makes a really good room heater as well
Chord Rumour X cables bi-wired to ProAc DT8's
The system sounds incredible with phenomenal dynamics delivered by the beast of an AMP.
Late to the party as usual.
I have a pair of DT8's, great speaker, but always room for a bit of fiddling!
Did this thread have any resolution (pun intended). ie. A new external crossover with schematic and recommended components (make, values etc.). Or did Stewart Tyler at ProAc get it right first time even with the obvious budget constraints?
Anyone?
These are hooked up to:
IBM Nuc running Roon
Fully balanced Cambridge 851D DAC
Advantage S2 Class A preamp, fully balanced
Advantage S150 fully balanced Class A power amp (2x150watts and capable of delivering 51 Amps (EEK!)). Makes a really good room heater as well
Chord Rumour X cables bi-wired to ProAc DT8's
The system sounds incredible with phenomenal dynamics delivered by the beast of an AMP.