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Cornwall II Upgrades / Capacitor Manufactures


rogerthataudio

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I picked up a nice set of 1986 oiled walnut Cornwall II's that are stock.  I already have a new set of Crites TI's for the tweets in the mail.  Looking for suggestions on:

 

1. Capacitor components for the 1.5 uF, 3 uF ( possibly 2 1.5uF ) and the 68uF. I want these to be nice for the next 33 years;-)

 

2. Squawkers any suggested modes that will improve sound quality, not that there are issues that I know of.

 

3. Any suggestions on the woofer?  I have heard of folks rotating the woofer 180 degrees to fight gravity pull in one direction for 33 years...

 

Thank you in advance for the advice! 

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I replaced the 1.5 uF and 3 uF caps  with WIMA units.

https://www.wima.de/en/

there are several US dealers. These are well-regarded in the  guitar amp and tube community

 

I used a Solen for the 68 uF.

I did not touch the mids. There is not much you do without major cabinet surgery since the driver of the mid almost touches the inside of the back wall.  but I rotated the woofers. 

I just replaced the caps. I did not rebuild the entire crossovers which were rather crudely put together in the first place.

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this is much lake asking "what flavor ice cream tastes best?" They are all a little different so you need to choose the ones that you like.

   An easy relatively quick and inexpensive method is to purchase a pair of the type of cap you think you might like in a small value (say 1uf) and then insert them into the signal path of your preamp input (between the CD and Preamp for example). Listen to the cap while it burns in and see what you think of the presentation. In this way you can cost effectively compare a number of different caps in your system. Note that cap forming (burn in) varies with different caps and some can take a long time to settle down (I have had some take up to five weeks but that is an ectreme case). There is little point in rolling caps if someone else is doing the choosing unless you have listened to their choice of cap and liked it. While a fuss this is the only way you will learn to know what you like and do not like and it is a great training experience to develop your listening skills.

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I would suggest doing as Moray suggests and test several.  It's pretty fun exercise as well.  I've done this many times over the years (particularly when I was building crossovers for various projects and looking for caps for preamps) , including A-B-X testing with three friends, and none of us could readily identify any differences.  Moreover, we couldn't even identify the same cap at a proportion that was better than chance. 

 

Without know anything about the sensitivity and specificity of your ears or what type of musical presentation you prefer, I couldn't make a recommendation for you. Some say they prefer oil or wax caps for a more laid back presentation, but again I cannot distinguish. 

 

Edit to add:  My ears are 50 yrs young and I cannot hear above 14 KHz.  :)

 

Edited by GFelber
clarity
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I wish my ears were that young! (58 and counting)!

 

So I am a big jazz fan and listen to others such as David Mathews, Tom Petty, Dire Straits, Steely Dan to name a few and I am critical on and really like the clarity and bright high notes in my music.

 

I have some Norman Lab 9B's that I replaced the phenolic tweets with titanium and updated the capacitors which currently outperform my Cornwall’s.  I'm hoping with the upgraded Cornwall titanium tweets and new caps I’ll get better and brighter highs.

 

Hopefully this will lead into more narrow suggestion of capacitors for the 1.5uF and 3uF.

 

I have attached some pics of my Norman Labs that really sound nice and the cabinets are +9 out of 10 with the original glass tops.  I bought these from the original owner.  He gave me the receipt that he paid $950 for the set in 1979.  

Norman Labs.pdf

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Without getting into a lengthy discussion about cap characteristics, tolerance, ESR (very important IMO), etc.. .  I typically use the Dayton 1%, Solen, Sonicap, Jantzen, and Clarity caps and generally stick with the lesser priced series with 5% tolerance, where available, for each brand.  More often than not, I'm using the Daytons, Solens and Sonicaps.  Again, based on my experience (and ears), I've tried the oil impregnated, silver, gold, etc and couldn't differentiate.    Some say the Sonicaps and Daytons are "bright", and based on your response above you may want to audition those.  They're pretty inexpensive as well.  

 

After my little experiments, I'm primarily using components based on design specs rather than perceived "audio" characteristics.  Every now and then I do go back to the box o' fancy caps for a test though...

 

 

Edited by GFelber
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3 hours ago, Schu said:

Fyi... aged hearing to say... 14Hz means you can still hear more than 90% of the audible spectrum because frequency increases logarithmic, not linear. 

 

 

Correct and primarily harmonics at that.  My point was in response to the OP's desire for "bright high notes" and that ears may not be as sensitive.   

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  • 2 weeks later...
On 2/16/2019 at 2:35 PM, Deang said:

 

 

I plan to build new crossover boards and get as much done as possible before pulling the existing crossovers to reuse the Inductors.  I am looking for clarification on the crossover circuit diagram attached.  I have marked the 4 capacitors and 3 inductors as labeled on the diagram.  I am not sure what I am looking at in the center of the diagram that I have marked up with a red circle.  Thank you for clarification so I can layout my new crossover board and create enough surface area to make a clean well organized crossover.

 

Thank you for the feedback!  

19022612270.pdf

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If I may respond to this,    I would not attempt to re use the factory inductors if your plans were to pull them off the OEM PCB. The red circled thing is the autotransformer (which can be re used).  I would suggest you use all new components and re use the autotransformer if you want to save some money. This way you will not destroy the OEM xover giving you the option to sell or go back to stock at some point down the road. 

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