Cornwall B3 crossover question.

[pete1729]

Back in May I bought some Cornwalls with mismatched midranges and blown mismatched tweeters. They have B3 crossovers and date to January 1984.

 

Well, I pulled the trigger on some NOS K-52-H drivers, I'm going to get Bob's tweeters, as well. 

 

My question is about recapping the B3 crossovers. The schematic calls for a 70mf cap on the woofer. How important is this cap sonicly? 

 

I am looking at prices on these babies and wanting to go with Dayton 5% in the interest of economy and then spending some more serious money on the 2mf and 5mf units. Is this foolish? I'm going to drive the speakers with a Mac 240, which I completely overhauled with Jim McShane's kit.

[Guest David H]

The 70uF is not overly critical.

 

A McShaned MC240, I'll bet that sounds great.

 

Enjoy your project.

 

Dave

Edited January 22, 2015 by GotHover

[OO1]

pleasde keep us updated at the B3 cap upgrade and the end results

[pete1729]

Well I went cheap. An Audyn 68MF on the bottom and Dayton 1% for the other two. My mental justification for this was deciding that having closely matched values between the speakers seems important. I am going to experiment with bypass caps. I have ordered a small variety of .01MF film caps.

 

My plan is to put the new drivers in both speakers and recap one crossover and compare it with an unrecapped speaker. This is a fun experiment to run with a friend to see if they can identify the recapped example.

 

Next I am going to recap the other speaker and add bypass caps on the squawker and tweeter capacitors and compare that to the recapped speaker without bypass caps.

 

I have four different sets of bypass capacitors that I plan to experiment with that in total will cost about $25. Cheap thrills  

[OO1]

Well I went cheap. An Audyn 68MF on the bottom and Dayton 1% for the other two. My mental justification for this was deciding that having closely matched values between the speakers seems important. I am going to experiment with bypass caps. I have ordered a small variety of .01MF film caps.

 

My plan is to put the new drivers in both speakers and recap one crossover and compare it with an unrecapped speaker. This is a fun experiment to run with a friend to see if they can identify the recapped example.

 

Next I am going to recap the other speaker and add bypass caps on the squawker and tweeter capacitors and compare that to the recapped speaker without bypass caps.

 

I have four different sets of bypass capacitors that I plan to experiment with that in total will cost about $25. Cheap thrills  

I recently recapped a set of B and E crossovers using NOS GE cans - the old sound is back - for the B3 - the Audyn 68MF doesnt sound bad at all - I guess that a 70MF wasnt available for specs matching

[boom3]

I recapped my Corn IIs with WIMA caps for mid and tweeter and a Solen 68 uF. The 68uf is a shunt cap that forms part of the low-pass network for the woofer. Generally speaking, you will not hear a difference changing out shunt caps because, as the name implies, the signal passing through them goes to ground. If the shunt cap had a real defect (leaky, out of spec) you would probably hear a diff. I replaced the old electrolytic 68 uFs with the Solens for sheer long-term stability. I wasn't expecting to hear any differences, even with the WIMAs in the series parts of the crossover, and I didn't. 

[pete1729]

Well, I just went ahead and recapped both of them, one with .01 Wima bypass caps on the squawkers and tweeters, the other with .01 Vishays. I found a pair of NOS K-52-H's to replace the mismatched K-52-K and K-55-M. I also got a pair of Crites tweeters to replace the mismatched and blown K-77-M and T35 tweeters.

 

First of all, They sound great. Oh hell yeah... Effortless from the bass up through midrange. Well articulated but not fussy. It's too early to tell if there is a difference between the two with their different bypass caps, That will take a few weeks of listening with a well sorted amp.

 

I also discovered after I sealed up the cabinets that I have the squawkers wired up out of phase. I will, of course change them, but in the mean time what difference is this making to my ears?

 

Also, is there some where on this forum where it would be appropriate to post about trading my mismatched leftover drivers?

[Guest David H]

Well, I just went ahead and recapped both of them, one with .01 Wima bypass caps on the squawkers and tweeters, the other with .01 Vishays. I found a pair of NOS K-52-H's to replace the mismatched K-52-K and K-55-M. I also got a pair of Crites tweeters to replace the mismatched and blown K-77-M and T35 tweeters.

 

First of all, They sound great. Oh hell yeah... Effortless from the bass up through midrange. Well articulated but not fussy. It's too early to tell if there is a difference between the two with their different bypass caps, That will take a few weeks of listening with a well sorted amp.

 

I also discovered after I sealed up the cabinets that I have the squawkers wired up out of phase. I will, of course change them, but in the mean time what difference is this making to my ears?

 

Also, is there some where on this forum where it would be appropriate to post about trading my mismatched leftover drivers?

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