Hi all,
Quick question in B&W 802 crossover rebuild. I replaced all caps in High and Mid stages with Mundorfs MCaps with good results.
After some time I replaced also bipolar 150uf cap (C5) in low filter with 150uf Mundors MKP and I hear noticeably less bass .
I cannot back original bipolar 150uf as I lost them but I've ordered bipolar Mundorfs and also I'm going to increase R2 a bit to increase bass level.
But is this normal effect in case of replacing elcos to polypropylene?
The good thing is this setup fits original place.
Regards,
EP
Quick question in B&W 802 crossover rebuild. I replaced all caps in High and Mid stages with Mundorfs MCaps with good results.
After some time I replaced also bipolar 150uf cap (C5) in low filter with 150uf Mundors MKP and I hear noticeably less bass .
I cannot back original bipolar 150uf as I lost them but I've ordered bipolar Mundorfs and also I'm going to increase R2 a bit to increase bass level.
But is this normal effect in case of replacing elcos to polypropylene?
An externally hosted image should be here but it was not working when we last tested it.
The good thing is this setup fits original place.
An externally hosted image should be here but it was not working when we last tested it.
Regards,
EP
This was also my experience with hi and mids - almost no tonal difference. And sure the box leased properly, strange thing that both speakers sound the same. May be these new caps need some time to warming?
It's not like there are no bass at all, but I remember that sound was more full bodied than now I'd say. And there are no changes in the setup. I'll try to replace C5 with bipolar as soon as I get them..
I found notes on R2 here B&W Matrix 802 Series 3 crossover rebuild . Note 2 at the very end of the page - Resistor R4 was added between resistor R2 and capacitor C5. This added more bass. The same result could have been achieved better by buying the Mills 0.75 ohm resistor for R2. Does it makes sense?
I still need to check theory on filters and influence of ESR so currently I'm just guessing.
Actually caps are pretty white )), maybe this is because of the color balance. I sourced them from well known places so I'm sure they are original.
So R2 and whatever additional resistance, alter how the bass rolls off, not so much overall bass level. More importantly, R5 improves (i.e. increases) the speaker's mid to treble impedance. This is a little weird, since it's in the bass section, so you have to consider C5 is a high pass filter to ground. R2 is there to control that slope, but also to prevent C5 from becoming a dead short. It's worth simulating it with Xsim to get a feel for how this R changes the overall impedance curve.
If your original C5 was high ESR, going to a MKP, which are VERY good in this respect, may have inadvertently altered this balance. I would measure, or find the specs on the original cap, and compare. My suspiction is that you lost quite a bit of necessary ESR.
Another way to tell is to look at the impedance plots before and after.
Best,
Erik
If your original C5 was high ESR, going to a MKP, which are VERY good in this respect, may have inadvertently altered this balance. I would measure, or find the specs on the original cap, and compare. My suspiction is that you lost quite a bit of necessary ESR.
Another way to tell is to look at the impedance plots before and after.
Best,
Erik
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So, put more simply, the resistance in the "second pole" of the woofer filter was R2 + C5(ESR)
If C5's ESR was reduced a great deal by changing the cap, there's at least one problem.
So, to make this behave exactly the same, you'd have to know the original ESR of C5, and add a resistor to make up the difference. This just restores functionality to what you had before. Whether you should make the changes B&W recommends I have no idea.
Best,
Erik
If C5's ESR was reduced a great deal by changing the cap, there's at least one problem.
So, to make this behave exactly the same, you'd have to know the original ESR of C5, and add a resistor to make up the difference. This just restores functionality to what you had before. Whether you should make the changes B&W recommends I have no idea.
Best,
Erik
Aye, what a horrible choice of caps. If you're gonna do an upgrde like this at least go whole hog and buy something that isn't "mundorfs cheapest version of a poly cap" /yikes.
Electrolytic caps are almost always over value. Did you even measure what you removed?
I'm gonna guess not.
R2 may help to tune a little, I would expect you need some more capacitance in there personally. Try adding 5uF and see what the difference in sound is.
Oh, and if amp volume, source, speaker location, seating location etc aren't exactly the same, your listening test are near void anyway.
Measurements on the other hand could help...
Electrolytic caps are almost always over value. Did you even measure what you removed?
I'm gonna guess not.
R2 may help to tune a little, I would expect you need some more capacitance in there personally. Try adding 5uF and see what the difference in sound is.
Oh, and if amp volume, source, speaker location, seating location etc aren't exactly the same, your listening test are near void anyway.
Measurements on the other hand could help...
I'm not saying that they're "horrible coloring" caps, I've used them with great success in series with a mid range in a 3 way, worked fine.
My point was simply that they aren't any real upgrade over what was spec'd already, it seems like this is tinkering for the hell of it, there's no measurements and it's all subjective. I read this post as "i've spent more money and I think they sound better but I've ruined the bass"
May as well write "I've got a rough idea of how a crossover works so I'll dump in my choice of caps based on nothing but branding and I'm sure it'll sound better... no wait, I ruined the bass response"
What makes this even more ridiculous is that there's PLENTY of room to improve all B&W crossovers, they're pretty bad really. Great cabs and drivers though.
Personally I think now mundorf are finally producing a "supreme" version of the EVO cap it's become my default high end cap for top level designs, if you're spending money, spend it properly.
AFAIK B&W spec mundorf supremes for all mid range up tweeters now anyway.... how old were these speakers?
My point was simply that they aren't any real upgrade over what was spec'd already, it seems like this is tinkering for the hell of it, there's no measurements and it's all subjective. I read this post as "i've spent more money and I think they sound better but I've ruined the bass"
May as well write "I've got a rough idea of how a crossover works so I'll dump in my choice of caps based on nothing but branding and I'm sure it'll sound better... no wait, I ruined the bass response"
What makes this even more ridiculous is that there's PLENTY of room to improve all B&W crossovers, they're pretty bad really. Great cabs and drivers though.
Personally I think now mundorf are finally producing a "supreme" version of the EVO cap it's become my default high end cap for top level designs, if you're spending money, spend it properly.
AFAIK B&W spec mundorf supremes for all mid range up tweeters now anyway.... how old were these speakers?
Good point actually ) This is exactly the case.
I've checked number of threads regarding the topic and messages were between "even entry level Jancens will be a great improvement" and "silver is a minimum". I agree that I'm on the bottom of the range but this was the plan. Anyway replacing elcos with MKPs should be at least not worse than before on my understanding.
I'm going to try supremes in the mids as soon as I get them, let's see.
But again, the story with bass is quite surprising, it should not be like this. Now my thinking is that the higher level of mids is the reason as it was mentioned earlier. So ESR metter + different caps are on the way.
My 802's are 24y old.
Yeah, now I'm scarred also. But there are sill some distance to the bottom exists actually.. ) Basic Jasions or WIMAs for instance.
Yes, all is on place. I'll proceed with measurements...
I think this is exactly the case, so looks like the bass in on place but mids are much brighter now. I'll play with different caps and resistors...
They are using supremes for hi and mid but there are these "horrible white" MKPs in low pass filter and one in mids... at least in 802D
802D
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800D
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Jancens and Jancens = Jantzen Cross Cap Capacitor in my prev posts )
Most likely ESR of the prev elco was ~0.2 ohms, and ESR of MKPs can be considered as zero if I got the point correctly.. Here is the suggestion to increase R2 to 0.7-0.75ohm (+0.2-0.25 to the original resistance) to improve the bass and this is exactly the delta between ESRs. Makes sense?
Most likely ESR of the prev elco was ~0.2 ohms, and ESR of MKPs can be considered as zero if I got the point correctly.. Here is the suggestion to increase R2 to 0.7-0.75ohm (+0.2-0.25 to the original resistance) to improve the bass and this is exactly the delta between ESRs. Makes sense?
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