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Old 18th May 2013, 10:29 PM   #1
DavidLS is offline DavidLS  Canada
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Default Crossover Curiosity

As I have written in thread below I have rebuilt my Ellis 1801 crossovers using platinum bypass capacitors (.047 uf), new resistors, and new wire. After about 100 hours of listening I decided to put the crossovers in the boxes I purchased to move the crossovers out of tight space in the speaker. In moving the crossover I broke one of the old tweeter capacitor connections off flush to the face of the cap. No way of re-connecting. Tweeter is dead on right channel.

So I have ordered some mundorf supremes to replace the original capacitor - 8.2 uf - mostly to try something different.

Waiting for them to arrive - today I got the bright idea of using a salvaged soniccraft capacitor from the woofer side (value is 5.1 uf) to get the tweeter going. The capacitor is bypassed by new platinum capacitors and voila everything works great. In fact sound is great.

So that is the curiosity - is there not much difference between 5.1 and 8.2 uf? Is the bypass capacitor playing a key role here (it didn't work on its own). New territory for me so just wanting to learn about what is going on.
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Old 19th May 2013, 12:27 AM   #2
Jay is offline Jay  Indonesia
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Quote:
Originally Posted by DavidLS View Post
So that is the curiosity - is there not much difference between 5.1 and 8.2 uf? Is the bypass capacitor playing a key role here (it didn't work on its own). New territory for me so just wanting to learn about what is going on.
I honestly doubt you can hear 47n of anything bypassing 8.2uF MKP. Remember that a cap labeled with 8.2uF may be measured 7.4uF if 10% tolerance is in effect (which is very rare to be honest).

If you hear the 5.1uF sound better than 8.2uF, that's normal, but assuming that you have good ears, it is a sign that the crossover is not perfectly designed. Why?

To make a good speaker crossover for 2 drivers you need to do these 2 things:

(1) The drivers must blend perfectly, they are said to cross each other at certain frequency, lets say 2.5kHz (where for example you need 8.2uF). Biggest issue is to get the phase right between the 2 drivers.

(2) Each drivers must operate in their comfort zones. Most tweeters will feel comfortable crossed as high as possible, away from their resonance frequency. So when you hear the tweeter individually, most probably the sound is less stressed if the tweeter is crossed above 2.5kHz (in your case 5.1uF will do this).

For a normal crossover, in my experience case #1 (driver a little bit stressed) is better than case #2 (drivers don't blend).
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Old 19th May 2013, 04:44 PM   #3
DavidLS is offline DavidLS  Canada
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Jay - thanks for the reply - good information. Not sure the sound is better - but also not noticing anything off and speakers definately sound better with two functioning tweeters. The speakers are mis-matched the way they are currently set up so the 8.2 mundorfs will get installed this week and will be interesting to see if I can hear any changes to the new caps and balancing the speakers with the same crossovers.

Find this whole crossover construction / components quite interesting.
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Old 22nd May 2013, 05:28 AM   #4
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david. would be interested to see what boxes you bought and how you wired/mounted them around the existing boxes. photos? i might think about doing similar for my speakers to allow for cap rolling as you have done.

Aaron
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Old 16th July 2013, 06:44 AM   #5
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Quote:
Originally Posted by Jay View Post
I honestly doubt you can hear 47n of anything bypassing 8.2uF MKP. Remember that a cap labeled with 8.2uF may be measured 7.4uF if 10% tolerance is in effect (which is very rare to be honest).
.

I can hear 10nF bypassing 10uF. While your argument regarding tolerance is correct, I find that two caps paralleled that equal X value do not sound the same as a single cap that equals X value. It is not the subtle difference in value that I hear. It is the completely different cap that I have added to the stack. Even the very small values.

Quote:
Originally Posted by Jay View Post
If you hear the 5.1uF sound better than 8.2uF, that's normal, but assuming that you have good ears, it is a sign that the crossover is not perfectly designed. Why?

To make a good speaker crossover for 2 drivers you need to do these 2 things:

(1) The drivers must blend perfectly, they are said to cross each other at certain frequency, lets say 2.5kHz (where for example you need 8.2uF). Biggest issue is to get the phase right between the 2 drivers.
I agree. If that much value change does not hurt the speaker, you either have some serious issues with the setup, room, etc..., or the resulting phase rotation does not hurt the design because the design does not track phase very well.

I believe that David is just starting to bring the speaker around, so it would not surprise me if was not really all that "close" to these speakers anyway. Meaning, he is just know getting to know them.
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Old 20th July 2013, 11:44 AM   #6
Jay is offline Jay  Indonesia
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Quote:
Originally Posted by Jeff Glowacki View Post
.

I can hear 10nF bypassing 10uF. While. your argument regarding tolerance is correct, I find that two caps paralleled that equal X value do not sound the same as a single cap that equals X value. It is not the subtle difference in value that I hear. It is the completely different cap that I have added to the stack
You are correct. You have very good ears. What i was saying is that such good ears are rare. I always bypass big cap with series cap in top speaker. Also there is burning in time until we can hear the real sound after chsnging caps.
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