Help to rebuild Canton CT-90 Crossover (I mean, almost the entire boxes)

[Bratwurst7s]

Sounds like a good plan. If you make your own coils you might as well make the entire crossover. It would probably be more economical in the end. The one crossover from my friend I'll get for what he paid for it (not much, I'll message you) but we would still have to find a second one and then there is shipping. Best thing to do is look at what prices you can find locally for the caps and resistors and coil wire and then compare and decide. My guess is that finding a second crossover will be in the €25 to €40 range. Shipping from here to you would probably be another €15+.

I haven't the slightest idea what brands are available where you are. Many of the economical brands that are often used by others in the forums aren't available over here in Germany. I've been using Mundorf MOX resistors, Mundorf elecrrolytics and Jantzen Foil caps and coils. The coils for the woofers were some of the the most expensive parts when I made new crossovers for my Speakerlab 7's so you would save a lot of money there if you roll your own.

Note that Canton used MKT caps for the tweters (C4). If at all economical for you I highly recommend using MKT or even better MKP. Using elcos on the tweeters will degrade the sound quality.

Cheers,
James

 

[morfeora]

Today I brought the woofers for repair, they so coils and cone where changed and estimated there will be no need for new coils, it seams this are ok. They will change only the cone, dust cap and will try to keep the surrounds (to try to keep the original look). Hope to have them tomorrow, lets see how they look and sound, but I guess this last thing should wait a bit.

Preparing my self for the crossover coil creation a question appear. How important is to keep the DCR in the same values as the original crossovers? Are those little values important in the overall performance of the crossover? I read a bit about it and some say its important to keep this values, others say is negligible value and lower DCR the better.

Capacitors and resistors should be buy on line in the States (was asking in different places without any finding), here in my Country this values are hard to find. (not too much crossovers enthusiasts here). I know Madisound Speakers, but they sell only very expensive caps. I so some in eBay but need to do a more detailed search. So far, even in the web, seams hard to find 120uf capacitors. Checked some Mundorf but their biggest is 100uF. Should I use two and summed in Paralel?

I will absolutely take your advice for a good capacitor for the Tweeters.

Just for the joy of fantasy... so a pair of AR6 speakers to rebuild in the repair shop for sale... now that I am into this rebuild hobby, I said "probably I should buy these!"

Cheers!
Rodolfo.

 

[Bratwurst7s]

Here is a link to XSim...
http://www.diyaudio.com/forums/software-tools/259865-xsim-free-crossover-designer.html
It's a very nice little crossover simulation program. You can use it to build your crossover see the results of coil (etc) DCR changes.

I think that you will want to stay as close as possible to the original values of the coils to keep the original driver balance. Changing the coil DCR can create dips or peaks in the response curve.

Now would be a great time for a US based member to jump in with recommendations concerning sources and availability.

One product/source that I've been using is Jantzen elcos bought from HiFi Collective. (no affiliation to either)...
https://www.hificollective.co.uk/components/jantzen-electrolytic-capacitors.html
Jantzen makes electrolytic caps in some hard to find sizes. They also have a line of MKT caps with a pretty wide variety of sizes.

I just don't have the knowledge/experience buying parts from the US to make a recommendation in that direction. Mouser and Digi-Key are the only US based sources that I use.
Parts Express and Parts Connection are 2 names that I've heard come up here but I have no personal experience with them...
https://www.parts-express.com/
http://www.partsconnexion.com/

Cheers,
James

 

[Bratwurst7s]

Oh. Using 2 caps in parallel to reach a value works just fine.

James

 

[morfeora]

Ok, I got the woofers repaired, They look lovely now, but figure out another big issue... Seams coil where changed for 8ohm, but they supposed to be 4ohm... This makes me review the crossover schematics and I made a discovered (not concerned with the woofer issue but the crossovers).

The CT80 Crossover from your friend share same L and C components with CT90 Crossover but in different variants.

All the coils in CT80 crossover you have are the same as in schematic CT90-3 (where this speaker configuration is used: W 4927, M 3669, T 4888) but with little differences with CT90's only in L2 and L4.
All the capacitors in CT80 Crossover you have are same as in schematic CT90 (uses W 3919, M 3669 T 2457)
Resistors did not correspond to any CT90 Variant.

Considering your friend's CT80 have same cross frequencies (450hz/4000) as CT90 and uses same same Mid (3669) and Tweeter (4888), this crossover will work perfectly in my CT90. My theory is they were tweaking components and make little adjustments or tried to have same results with diferente components.

To make the CT80 Crossover almost the same as CT90-1, I only have to eliminate one capacitor (C5) and one resistor (R5) -capacitor and resistors in parallel with the tweeter- and, change R2, R3, R4 to match CT90-1 values, same for C3 (Mids capacitor) and C4 (Tweeter capacitor). But at the end, I think it will no be necessary to change anything, think CT80 Crossover you have may works pretty well in a CT90 Speakers.

If we can find another CT80 crossover exactly the same as you already have James, I think will be perfect... the best and economic in terms of work and money.

Just in case anyone needs to rebuild a CT80 crossover, here are the exact components of the variant you have. You James already have it, except for the exact values of the coils.



CT80 Crossover coils: (taken from CT90-3 schematic)


CT80 Capacitors (taken from CT90 schematic)


The only resistor shared between CT80 and any variant of the CT90 crossover is R1:


You James suggested to find a new pair of woofers (which I definitely agree). I think there is something more to tell, but I have to go now... will be back later.

Best,
Rodolfo.

 

[morfeora]

I forgot to post the lovely look of the woofers after repair... they did a really good job changing the cone.


This are the Tweeters the speakers came with, non branded I think, cheap tweeters:




cheers!

 

[Majklufka]

Hi Gents,
This is my first post after reading a many and I would like to share what I have.
I found your nice posts about Canton CT speakers very nice and this inspired me to upgrade/recap mine Canton CT 80. Still play with XSim to see the impact of different configurations to the output characteristic. In parallel I've opened the cabinets and recognize that in one box I have crossover revision -0 and in second revision -2, hence i decided to ask Canton for help and they shared schematics with me. You should find them attached. If not let me know...I'll try again.
As in case of CT 90 there are several crossover generations. And I have -2 which Canton did not send, but it looks similar to -1 with difference of R1,R2 and C4. Honestly said -0 sound a little better , So I'll do some kind of mixture between -0 and -1 to bring the best result.

Will keep you informed about results..
BR
Michal

 

[morfeora]

Hi Michal,

Interesting experiment you are doing and thanks for sharing your information.

We (James and I) has been studying in detail the different variants in crossovers from the CT90, CT80 and Karat60 (seams all this references are very similar regarding the crossover components including the Karat40 which we do not have the schematics to compare. Most of them use same tweeter (4888 or 2457) and mids (3669) and has same crossover points 450/4000Hz). James concluded regarding the CT90 that variant 3 could be the most accurate sounding configuration cause is the result of some time tweaking the design of the crossover and some little variations in the drivers. (I am was totally agree with him once he pointed the arguments), so we are in the process to rebuild this variant using an original Karat40 crossover which use same Coils.

For your experiment, attached are other two variants for your CT80 that seams you dont have CT80-2 and CT80-3. (Are zip files because the size file limit)

One think more. In my understanding, to have a proper graphic return in XSim, mesures of the drivers should be made. Did you did this by yourself or did you find the the drivers measures some place? Will be really great if you can share this mesure files with us.

I hope you have a good time doing the experiments, please let us know your results and conclusions.

Cheers
Rodolfo

 

[Teradacto58]

If your sister lives in the States get a Parts Express Catalog,,,,lots of good replacement parts and drivers reasonable!!!

 

[Bratwurst7s]

Hi Gents,
This is my first post after reading a many and I would like to share what I have.
I found your nice posts about Canton CT speakers very nice and this inspired me to upgrade/recap mine Canton CT 80. Still play with XSim to see the impact of different configurations to the output characteristic. In parallel I've opened the cabinets and recognize that in one box I have crossover revision -0 and in second revision -2, hence i decided to ask Canton for help and they shared schematics with me. You should find them attached. If not let me know...I'll try again.
As in case of CT 90 there are several crossover generations. And I have -2 which Canton did not send, but it looks similar to -1 with difference of R1,R2 and C4. Honestly said -0 sound a little better , So I'll do some kind of mixture between -0 and -1 to bring the best result.

Will keep you informed about results..
BR
Michal

Hi Michal,

First, Welcome to Audiokarma.

Take a look at the schematics. Your /0 version should have a 2457 tweeter and 3125 woofer. With the /1 and newer they changed to a 4888 tweeter and 4903 woofer. Probably not a lot on difference in sound but there is enough difference that Canton did quite a bit of crossover tweaking in the later versions to dial them in.

If you ever find yourself needing replacement drivers the Karat 40 has identical drivers to your CT 80s (version to version). The 3669 mids are used in all versions of the CT 80 and 90, (not sure about the 70) as well as the Karat 40 and 60. The 2457/4888 tweeters seem to follow the version changes in the other speakers also.

Have fun,
James

 

[morfeora]

If your sister lives in the States get a Parts Express Catalog,,,,lots of good replacement parts and drivers reasonable!!!

Thank you Teradacto58. I already checked part express and spend some time seen parts.

Today I carry my cabinets to a friend who will take care of to cover the hole someone did on the front of the cabinet. My friend also concluded that the original finished of my cabinets were the natural wood variant, so, he will be puling out the black an return to the original lovely wood finishing




Don't know how much time he will need but when the job is done will be posting pics of the new look.

Cheers,
Rodolfo.

 

[Bratwurst7s]

Thank you Teradacto58. I already checked part express and spend some time seen parts.

Today I carry my cabinets to a friend who will take care of to cover the hole someone did on the front of the cabinet. My friend also concluded that the original finished of my cabinets were the natural wood variant, so, he will be puling out the black an return to the original lovely wood finishing

View attachment 1091415
View attachment 1091418

Don't know how much time he will need but when the job is done will be posting pics of the new look.

Cheers,
Rodolfo.

Very very cool! With a little luck the original lacquer finish will have protected the veneer from the black paint and your friend will be able to reveal all of that beautiful Walnut veneer.

Cheers,
James

 

[Bratwurst7s]

You know, I'm being a bit dumb here Roldofo.

My Karat 60's have all of the exact same drivers that your speakers should have. And I do need to open them up and re-cap the crossovers. When I do that I will test a mid and a woofer with the Woofer Tester 2 kit that I have. (it won't do tweeters). Then I can share the results with you for use in XSim. I can't do a sound sweep but at least you would have the T/S and impedance sweep results. It will probably take me a week+ to get some stuff cleared out of the way but I'll get it done.

Cheers,
James

 

[morfeora]

My Karat 60's have all of the exact same drivers that your speakers should have. And I do need to open them up and re-cap the crossovers. When I do that I will test a mid and a woofer with the Woofer Tester 2 kit that I have. (it won't do tweeters). Then I can share the results with you for use in XSim. I can't do a sound sweep but at least you would have the T/S and impedance sweep results. It will probably take me a week+ to get some stuff cleared out of the way but I'll get it done.

That will be great James, Is just for the joy of tweak and play with the software, but is not a need as we already know where to go and what to do regarding the crossovers
Cheers!
Rodolfo.

 

[Majklufka]

Hi James,

thanks for invite me here...
I've opened both speakers and found same drivers 2557(4903),2259(3669),2457(4888), so I'm happy to have the same boxes. I've repaired terminals because old ones were broken. Regarding crossovers I plan to do external ones to have possible and quite easy way back to the original ones. Unfortunately was not able to find Canton drivers charasteristics, so I've tried to use similar drivers just for comparison between crossover with and w/o drivers. Characteristic is diferrent but that what I've expected.
Just FYI here is the picture of modified crossover and link to FRD & ZMA driver files, to let you try.

http://www.rjbaudio.com/Audiofiles/Driver FRD files.html

Have a fun and nice weekend

Michal

 

[morfeora]

Some days ago I pass by my carpenter friend workshop. He already toke off the black painting and now the a little more of the "history" appears. Someone have already try (not in a good way) the restoration of the cabinets. There is a burn in both of the cabinets and some other marks on the wood. Fortunately my friend is really a professional doing wood restoration.

The see the original wood is pretty amazing and shows how well this cabinets were made.

In the other hand, different from my friend, I think they were originally in black. Thinking this mainly because the sticker in the back of the cabinet. Looks pretty original and no marks of paint or damage, a think hard to believe if the cabinet where repainted before to change the color. Any way, I prefer the wood finishing.

Here are some pics of the current state of the process.







Here the sticker Whit any mark of damage or painting. What makes me think almost for sure the cabinets where originally in black.


Cheers,
Rodolfo.

 

[Bratwurst7s]

Hey Rodolfo! Looks like your carpenter friend is doing some good work. Always good to have a carpenter as a friend.

I've only seen 2 pair of CT speakers in the flesh. CT 800 and CT 80. Both sets were/are black but one can see that they both had/have wood veneer under the paint. In comparison my Karat 60's were produced in about the same time frame and are obviously MDF under the black paint. Something that makes the CT series more desirable and attractive imo.

I live up on the 8th floor and my play/work room window is right above where the DHL transporter always parks. Yesterday I watched as he parked, got out and went into the shopping center next door, got back in his truck and then drove away. At no time did he even approach the building where I live. 15 minutes later I got an email that the package with your 1st tweeter couldn't be delivered because nobody was at home. Typical DHL, a pack of lies every time. So I'll be walking over to pick up your tweeter in a little while. I expect the same thing to happen with your crossovers. Lucky for us the post office is only 15 minutes by foot from me and I'm off of work for the next few weeks.

I may have found a 2nd tweeter for a reasonable price. I'll let you know when/if I can confirm that.

Cheers,
James

 

[morfeora]

I so sorry to have you working out this much during you vacations you know how much I appreciate you already. Thank you.

Now I am pretty sure this will have a very happy ending.

Cheers,
Rodolfo.

 

[morfeora]

Ok, have been some advances in the cabinet restoration.

Today my carpenter friend toke me by surprise, he knock on my door calling me to see the new aspect of my cabinets (the workshop is about 2 houses from mine). There are not words to mention this, you have to see and compare with the first pictures of my awful black cabinets. He already cover the front holes, putting a peace of wood on the hole and applying a new oak veneer to this part of the front... not visible marks of the, now forgotten, ugly front hole. In general is like a new sun rising

My friend and his family have been Luthiers at least for three generations, his Grand Father started the workshop and now his father, who is 80 y/o, is a recognized acoustic guitar Luthier (still working -stand- on the workshop despite an almost severe osteoarthritis), my friend is an expert restoring pianos. Sadly, this art is not recognized properly here, my friend is now open to restore other wood things like my speakers.

Here are the pics:





The front hole is gone now


This was the first hand of wood sealant, still need one more and after that a hand (or two, do not remember) of lacquer. So, more improvements in finishing to come.

Cheers,
Rodolfo.

 

[Majklufka]

Hi Rodolfo.....really amazing work. This project is going definitely by good direction. Thumbs up.
Michal