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

[morfeora]

Hi Everybody,
I am Rodolfo, electronic musician from Colombia. I have found you (AK), looking for some help on the web to solve the sad story I am about to tell.

I run a small record label here in Colombia, TBM Music. Been working on music production and digital mastering (mostly for my own music) like ten years ago , not any expensive equipment, just a laptop and a pair of Technics Sb-X5 Linear phase speakers from 70's and Technics SU-7700 Amplifier, both of them made in Japan... which sound amazing to me. The thing was that for a personal inconvenient (Separation of Property) I no longer have these. So I was trying to find in the States (easier to ship to Colombia) this same speakers again but didn't find any (and only a 400 dollars. I know, not too much to find a decent speakers).

After some time I decide to look in Mercado Libre Colombia (kind of eBay for Latin America) and so A pair of Canton CT-90 speakers saying "Excellent German Canton Speakers" Did some research on the web and say "Wow! 20hz - 30Khz frequency response, Made in solid wood (Oak), German Made, This has to be good" I felt in love. I so the tweeter was not the originals and woofer was poorly repaired but for my experience I knew this was something I can fix and find (the tweeter even when the only place where I so them was in eBay Germany and mostly no ship to the states (where my sister lives so she can send it back to me to Colombia). So I agree with the seller to buy them in this condition.

But, when they arrived at home I have a total disappointment:

• Woofer out of the box (poor wood when the screws hold the drive)
• They made a hole in the front of the cabinet to create a "bass reflex" port ("how can they did this to the lovely Oak" I said)
• They put a cheap tweeter in the back hole (I guess originally for air flow) of the cabinet
• But the worst... No original crossovers (I knew this could be hard to find or rebuild)
  
• Non of this mention in the product description.... any way, the seller did not accept this poor condition and no money back (laws in Colombia are not good for the consumer)

So, my only chance is to rebuild almost entirely this speakers. Start searching and I came back to life again when so the post by @Bratwurst7s about Canton CT-1000 Tweeter where he posted the crossover schematics for this reference. I say, "Ok, this boxes use same tweeter, this crossovers may works on my CT-90".

Now I am looking mainly for the crossover schematics for the Canton CT-90 and all the help and information that you guys can provide to me. I cant say that I have all the budget to buy and do everything right now, but for sure I will do it and start working as soon as posible. I do not now if this can be a lost cause, but I have to try it.

Thank you all in advance,
Rodolfo.

 

[Bratwurst7s]

Hi Rodolfo,

Looks like a bit of work but I think that we can eventually find what you need. For some reason CT 90's don't seem to come up as often as CT 80's and 100's. But in good working order your 90's should be fine sounding speakers.

First thoughts...
Good that you posted the photos, I have a better idea of what is going on. Please post photos of the back side of all of the drivers. All Canton drivers will have a small yellow sticker in the magnet with the 4 digit part number. Then we can see exactly what you have and what we need to find.

If all that the last owner did was remove the bass port from the rear and relocate it to the front then at least you can return it to the correct position and it will function correctly. If the modified the tube that will be a problem.

The tweeters and mids should be the same as the CT 80, CT 100 and possibly CT 120. The CT 800 and 1000 drivers will also most likely work for you even if they have a different PN. A good friend of mine has a pair of CT 80's and we've done some work on them. His CT 80 uses a 2457 tweeter and a 3669 midrange. With a little patience and time we can find those for you on ebay.de. In fact there is a (1) 3669 mid on ebay right now. You can expect to pay €30-40 per driver although from time to time they pop up as a pair for decent prices.

Concerning the crossover. When we had the crossovers from my friends 80's on the workbench I mapped them out and made a schematic in xSim. The CT 90 crossover should be very similar with the exception of the woofer and lower end of the mid. The CT 800 uses all of the same size drivers but being closed probably has a different woofer (same 260mm size tho). So I'm thinking that if we can't find any CT 90 crossovers the CT 800 or 80 might be a good starting point. The CT 800 crossovers show up on ebay quite regularly and there is a listing with 2 there right now, but the price per piece is a bit high.

Concerning your binding posts. Not a big problem, I'd recommend replacing them anyway, they break fairly easily. See posts 3 and 5 in my Karat 200 thread...
http://audiokarma.org/forums/index.php?threads/canton-karat-200-thread.751202/

Give me a little time and I'll start searching for a schematic and parts for you. In the mean time I'm attaching the schematic for the CT 80 that I made and a photo of a CT 80 crossover.



More later,
James

 

[Bratwurst7s]

So I'm looking and see that the CT 800 uses a 2965 woofer. If your 90 uses the same one that would be good because they show up on ebay regularly.

Cheers,
James

 

[Bratwurst7s]

I found one photo of what is supposed to be a CT 90 crossover although I can't see any silkscreen on the pcb showing the model number.



Cheers,
James

 

[morfeora]

Hi James and thank you very much for your help.

I tough the same as you about the crossovers. First tough the one from the CT-800 could work, but now looking for the crossover points in the CT-80 (450hz/4000Khz) I think to rebuild this same crossover could be a better way to go because share the same cross points with the CT-90 (in case that is impossible to find the originals. I've done the searching with no results). Basically the only difference between the two models is 2hz in the bass response. (CT-80 from 22Hz, CT-90 from 20Hz HiFi Wiki says). Can you upload a bigger image of your schematic for the CT-80 Crossover, to avoid wrong lectures in the numbers (btw I love kde!).

About he drivers, my plan is to send them to recoil, or maybe just change the paper and foam (know a place here where they do a pretty good job, after that they look and sound like new) any way, even when they look awful, are sounding good, so this is probably not a concern and they are original ones.

My second concern after the crossover is the tweeters, I definitely need a new original pair. I so some in ebay Germany but it seams that now I cant see this content. any way was priced high 82 dollars (this is the link of the product in eBay, may be for region things I cant see it anymore) If you can help me to find a pair would be great.

Now that you mention, do you think the back port has a tube in your friends the CT-80? this is actually a bass reflex system? I think in mine there is not tube any more and the one they put in the front is just a generic one not the original.

About the binding posts I definitely want to use the ones you used, looks beautiful

Thank you again James for your help and good will to look for information for me, you cant Imagine how frustrating I felt when see the state of this speakers when they arrive. Now everything is promising

Even when there is no need to buy new mids and woofers, I will look for the stickers in the back. Just for the record and in case someone else need this info.

Cheers,
Rodolfo.

 

[Bratwurst7s]

I'm happy to help, that's half the fun of being here.

After I posted the above I looked at HiFi Wiki and saw that the CT 80 & 90 have the same crossover points. The 800 has the same woofer/mid crossover point. So I agree that the CT 80 crossover would be a better place to start, only the inductor, cap and possibly resistor for the woofer would need to be changed. IF the 90 uses the same woofer as the 800 (and that is entirely possible, even likely) you could use the woofer section from the 800 crossover.

How urgent is this for you? Because time and patience is your friend. Sooner or later a pair of CT 90 crossovers will show up here. Same with tweeters. I've added the CT 90 to my list of ebay searches and can keep a close eye out for all of these.

Concerning your woofers. If they have foam surrounds they are not original. All Canton woofers and mids have rubber surrounds. But the photo that you posted looks like a Canton woofer. By all means do take photos of all of the drivers front and back. Then we can nail down exactly what you need. Concerning the stripped screw holes. You can just fill them in with wood putty and rotate the woofers, then mark and drill new holes.

Concerning tweeters. I do very regular ebay searches for a lot of Canton stuff, like every 2nd day. The tweeters that you need will normally go for about €30 each. I don't know just what the exchange rate is at the moment but $82 for a PAIR sounds about like what you will normally see here in Germany.

The forum rules are that while we are allowed to discuss ebay stuff we aren't supposed to post direct links or listings. If I see something that you should know about I'll post it directly to you in a "Conversation".

Concerning the port. Looking at the photo that you posted it sure looks like there is a tube there. And the photo of the tweeter stuck in the back port hole seems to show a residue/ring that looks like where there was a flange. It sure looks like someone decided to move the port from the back to the front. Might be worth checking. In any case with the CT 80 having an 8" woofer the port is likely to be a different size. I'll try to find out but this will be most likely the most difficult bit on information to find.

My friend is also my co-worker and I'm on vacation the next 2 weeks. But he will be coming over on New Years Eve to celebrate with us. I don't know if I will see him before then. We had been talking about him bringing his speakers to me to deal with a woofer issue but I don't know if he will have the time before the end of the year. I'll ask. That would be convenient for both of you. He also has 1 extra crossover. I'll ask him if he would be interested in parting with it.



I'm a long time openSUSE Linux/KDE fan.

Cheers,
James

 

[Bratwurst7s]

Oh. Btw. The crossover schematic was done from taking apart a crossover and measuring all of the components with an LCR meter. That's why my friend has an extra crossover. He bought it so that we could take the time to map it out before opening his speakers. So it's important to note that the values in the schematic are derived from what I measured and are NOT from Canton. I'm confidant that the measurements were accurate but there is always room for error.

Cheers,
James

 

[morfeora]

Ok, now I have a better picture of the inside of my speakers.

I am completely agree with you about to tweak the CT-80's crossovers changing the woofer with the CT-800's. Now I have pictures of the stickers, It is not entirely clear (only one woofer still have the sticker)but I think is 3210.

Woofers are 3210
Mids are 3669

Even when there is no hurry, could be interesting trying to build the crossover from the CT-80 Any way I am absolutely interested in the originals... hope you are right and soon or later they appear in eBay with available shipping to The States (many things in eBay Germany are not shipped outside Germany. Hope I am wrong whit this).

In conclusion, I am interested in the original crossovers, I can wait.

But In the mean time I can see how much could cost to rebuild the CT-80 mid/high with the CT-800 low (there is a place here where coils are building). And don't worry, I understand the possible difference between your measures and the original components. Any way I can be interest in your friend's crossover.

The woofers both seem to have rubber surrounds, but they have different kind of paper cone. One could be entirely original (but seems someone painted with some kind of material, dust cover are changed in both), the other one is obviously repaired (not centered properly).

About the tweeter, the one I so was 82 dollars (70 Euros just one, not the pair). I will do the same as you in ebay germany (CT-90 to list searches). Any way is hard to me to understand because most of the content is in Germany... so, your help here is much appreciated. Will be waiting for good news from you in my inbox

About the ports, I am happy to say they are there, it's a very short tube and seams I can polish them to a normal state

Thanks again for the hi res image of the crossover.
Check the part number of the woofer and let me know your toughs.

Here, no so long time, but Debian/KDE Lover

Keep in touch,

Rodolfo.

 

[Fairlane]

Rodolfo, welcome to AK!

Hey those woofers may not be the originals but the sure look German to me and the cast frames tell me they are good ones. Perhaps Brauns?

Those have been abused for sure but it does not look impossible. Especially with your determination.

Kirksaeter, Braun, Quart are other German makers you may be able to use some of the drivers from. They seem to be very similar especially in the tweeters.

Good luck. Will follow this thread with interest. Love German speakers.

 

[morfeora]

Hi Fairlane, Thank you for your welcoming.

Yes, I am very determined to fix this speakers, have no other option.

The basket of the woofers are branded with the Canton logo and, in the back says they where made in the Federal Republic of Germany. The thing is that, at least the cone were changed.



Cheers
Rodolfo.
PD: Your Brauns looks strangely beautiful

 

[Bratwurst7s]

Hmn. I don't know why I'm being so dumb the last few days, must be getting old.

My Karat 60's have the same 450hz/4000hz crossover points as your CT 90's. And while they have much smaller cabinets than yours they are still ported and have a 10" woofer, and most likely the same mids and tweeters.

I need to re-cap them anyway so I'll just do that in the next couple of weeks. I can do measurements on the crossovers then and make a schematic. And note the driver part numbers. In the mean time I'm still searching for the correct/exact woofer part number for your speakers.

I found a pair of woofers from some CT 800's for a very good price and with international shipping. But the CT 800 is a closed box so those woofers won't work well in a larger bass-reflex box.

Cheers,
James

 

[Bratwurst7s]

Btw, I'm still looking for info on the 3210 woofer. Not finding anything so far except hits on subwoofers. Interesting that the photos of CT 90's that I've been finding show 2 different dust cap sizes, small and a bit larger. But all of them look much smaller than the dust caps on your 3210 woofers.



Cheers,
James

 

[morfeora]

I am pretty sure my woofers were repaired (cone changed)and, as cables that go in to the coil pass through the cone in opositive sides, they (people who changed the cones) decide to cover them with the dust cap, needing a bigger cap than original speakers where you can "see" the cables going to the coil in the front of the cone.
Like this.

About your searching related to my woofer reference, it seams not weird to me you find results related to subwoofers as this speaker can goes from 20hz in frequency response. (One of the main reasons I fell in love with this speakers).

Will be very helpful to know your karat's crossover, for sure will enlighten can I say now "our" building process?

But as karat 60 response goes from 22hz I am pretty sure they do not use the same woofer as CT-90's.

Have an idea, will do a search in the wiki for other Canton same age models with frequency response starting at 20hz, may be this show us something.
Cheers.

 

[Bratwurst7s]

Sounds like having your Tech check the woofers is an economical way to start.

You are most likely correct that the Karat woofer is different than yours. But the 2hz difference can easily be due to the larger cabinet size.

I've gotten interested now and I'll keep looking to find more information. Ideal would be to find someone that has a pair of CT 90's and is willing to look at the driver part numbers.

Concerning the sub results. I actually got very few search results but a number of them were related to different sub-woofers, but nothing that actually stated something about that particular woofer. Probably just some weird google thing.

I'll call my friend tomorrow and ask about the crossover. He was out today.

The pushed in dust cap in one of your mids can most likely be pulled out by taking a straw or paper tube and just sucking it back out. Sounds yucky but it usually works.

FYI, from the different Canton drivers that I've checked most woofers have a DCR of about 3.4 to 3.6 ohms, mids and tweeters have usually been measuring 3.8 to 4 ohms.

Cheers,
James

 

[sx-70]

@Bratwurst7s

Member of the year nominee.

 

[morfeora]

I will send my woofers to repair this week, will be posting photos once I got them back. Thanks for the DCR values, probably they will ask for some details related the speakers.

The trick whit the straw sounded amazing, tried but notice the paper in the cap is really soft. Seams where pushed and backed up several times. It worked to put it out, but the mark on the paper is still there. As long the speaker works properly, think I can live with that.

About the 2hz difference, yes, agree with you James, could be the cabinet who push the response a little bit down. If the repair of my woofers do not give me good results, we can try with other models woofer.

Looking on the web for the crossover find a person (seams German) who made a re cap work on a CT-90's Crossover, unfortunately not high quality pictures: http://www.revisound.com/res_LSB.htm (scroll down a little).

Talking about someone that have the same speakers, its kind of weird that not too much info is around related this particular reference... not to much people have this CT-90 or what?

Cheers.

 

[morfeora]

I am happy to let you know an email from Canton just arrive in my inbox including the crossover schematics for all CT-90 variants (seams were 4 different variants). Everything is clear now, I know which of them my speakers could be.

I posted that my woofer reference was 3210, saying the last digit was hard to read, I was wrong with this reading. Now is obvious... what really is its 3219.

So my version could be CT90 (uses 2477 Tweeter) or CT90/1 (uses 4888 Tweeter) both versions uses same Woofer and Mid

I have this:
Woofer: 3219 (confirmed in my speaker sticker)
Mid: 3669 (confirmed in my speaker sticker)

Now I have to decide which crossover version to build depending on the Tweeter I find. Which could be more easy to find 2477 or 4888 (have seen this in eBay).

From my perspective will like to rebuild the one who uses the 4888 Tweeter, this crossover have two components less than the other version.

What do you think James?
Now I do need help to understand the values for the coils, I do not understand what this group of numbers means.


The last number could be in mH?
For example: L1 could be 1,0 mH.

What other letters and number mean? are they talking about the caliber of the wire and the core type? Ferrite or air?

For a fast picture. This is from the CT90/1 version:



So far very very happy and optimistic having this, is a lot of progress in my project

Cheers!
Rodolfo.

 

[Bratwurst7s]

This is great news! It brings a lot of clarity.

So we now know that your woofers are original but badly repaired. That gives hope that they can be rescued.
The mids check out. No problems there.
The tweeters. I see the 4888 fairly regularly here. Not so much the 2457. The 4888 is what my friend's CT 80's has and we had to find one to replace a half dead one last year.

For the coil info. I've been puzzling over this for a bit. The CT 800 crossover schematic that I have shows very similar numbers. My guess is as follows...
Using L1 as an example I believe that the "350" stands for 3.5mH and the "1.0" stands for 1.0 ohms.
L2 = 0.48mH 0.6 ohms,
L3 = 2.35mH 0.71 ohms,
L4 = 0.135mH 0.6 ohms.
Compare those numbers to the coils in the CT 80 crossover that I measured. The numbers are very close. Close enough that I think strongly that it's a workable theory. (the DCR isn't shown in the schematic that I posted but looking at my notes the resistance numbers are very close to what I measured)

I talked to my friend today. I'll have the CT 80 crossover in my hands on New Year's Eve.

One thing that I'm not clear on. Exactly what tweeters are installed in your speakers now?

We're making progress.

Cheers,
James

 

[Bratwurst7s]

@Bratwurst7s

Member of the year nominee.

Thank you very much for the compliment. My feeling is that there are many here that are far more deserving. I'm just a little pea in the pod having fun.

Cheers,
James

 

[morfeora]

I compared your pics of the CT-80 Crossover (where we can see reference numbers) whit the CT90/1 Schematic.

Same components in both:

L1: 3.50mH - 1,0 Ohm - Ref: 3000 (ferrite core coil)
L3: 2.35mH - 0,71 Ohm - Ref: 1873 (ferrite core coil)
C1: 120uF - 35 VAC - Ref: 1615
C2: 47uF - 25(23) VAC - Ref: 2801
R1: 1,2 Ohm - 9watts - Ref: 1617
This is almost half of the crossover.

The other components are different.

About the tweeter I have the feeling in same direction as you, try to find the 4888. The tweeters I already have seams a pair of generic tweeter, no brand or mark. Will post pics once I arrive home.

Tomorrow woofers will go to repair.

It seams pretty easy to create the coils by myself. Here is a calculator where the mH and Impedance value can be set, and they give the inner coil circumference and the total lengt of the wire. Seams an economic and precise way to do it. What do you thing?

http://www.steam-engine.org/coil.html

Yes a lot of progress
Cheers,
Rodolfo.