Canton Karat 30 tweeter replacements

[kurtisthesane]

I have an old pair of Canton Karat 30s that I have had around for a while. They never really sounded that great. When I put them up on craigslist, someone pointed out that the tweeters did not look stock. I pulled off the grills, removed the tweeters and noted the were Motorola super tweeter. I also discovered that one of the inductors and resistors on the crossover had been changed (not sure if direct replacement or modified for the new tweeters) and fuses were installed. Someone liked these loud!

I am planning some upgrades for the crossovers, if I can find some tweeters. Original Canton units seem unavailable, especially in pairs. AND I still don't know the original part numbers (help anyone?). The original tweeters are 1" aluminum/magnesium domes with 4"/4 screw baffles.

I would appreciate recommendations and information.

 

[picowallspeaker]

Hi, the design is "old" since the woofer is BIG! Nowadays you would cross a bit lower and use a waveguide ( to meet directivity at XO frequency ).
Nowadays you won't see that fully ferrite covered inductor for lowpass.

So, reading above, the only thing that comes to my mind is a Seas DXT tweeter and ferrite-core or air wound coils

 

[system7]

We do seem to get an extraordinary number of old speakers with blown tweeters round here!

And dubious replacements!

These look like old Motorola 100mm Piezo jobbies...

The filter looks like second order, 8" bass plus 1" metal tweeter with attenuator:

A 104mm SEAS DXT is not the worst alternative I have ever seen...

Won't work entirely differently from a 92mm Monacor HT-22/8:

Crossovers look like this in the diy world:

You need quite an investment in tools to do this sort of thing, but actually, I can never resist a good old wooden box and some driver and crossover upgrades. You can usually do better than the original with a bit of effort.

 

[kurtisthesane]

Hi, the design is "old" since the woofer is BIG! Nowadays you would cross a bit lower and use a waveguide ( to meet directivity at XO frequency ).
Nowadays you won't see that fully ferrite covered inductor for lowpass.

So, reading above, the only thing that comes to my mind is a Seas DXT tweeter and ferrite-core or air wound coils

The number on the board for the replaced inductor is 1168. I found a forum post on the crossover here for the Canton CT800 which also uses the missing 1168 inductor:
Canton ct800 passive to active crossover solutions
There is also an attached schematic.


Looks like the 1168 should be a 0.25mH inductor, if I am reading that schematic right? What is the difference between a 0.10 vs 0.25 in terms of crossover frequency. What is the function of the large, ugly resistor (which I assume is also a replacement? (I expect to find the correct resistor value under the ugly one.) If you change the inductor, do you have to change the resistor value too? (not really familiar with the physics or engineering principles of crossovers)



I looked at the Seas DXT, and it looks like it may have more range than the canton tweeter had--or was used for back in the dark ages (the 80s). If I went with a DXT and was replacing crossover parts, would I want to change the crossover frequency and move it a little lower than stock? Or lower than it is now with the 0.10mH inductor?



Thanks for the help. Feel free to recommend links to educated me on details we don't need to revisit in this post.

 

[kurtisthesane]

I did finally hear back from Canton:


It definitely was a 4 Ohm driver! 3257 --> inductorl PK 40 - 165 - 1,12(f.FK52)1,60- 1,70mH 1168 --> inductor 2 - 026 - 060,25- 0,27mH


They also sent me schematics for the crossovers. There are apparently 3 versions. I have version 30/2.


The following is a proposed parts list:

Dayton Audio RST28A-4 1-1/8" Reference Series Aluminum Dome Tweeter 4 Ohm


Dayton Audio 0.27mH 16 AWG Copper Foil Inductor Crossover Coil

Mills 12.5 Ohm 12W Non-Inductive Resistor



Other 4 ohm alternatives seem to be:

SB Acoustics SB26ADC-C000-4 Aluminum Dome Tweeter

SB Acoustics SB26CDC-C000-4 Alum-Ceram Dome Tweeter



But they are $50 and $58 respectively.



Any recommendations from experience with these tweeters? If I understand the physics of crossovers, changing the tweeter to a 6 ohm totally changes the crossover frequency and likely the overall loudness, too?



I assume returning the crossover to the original specs is the best idea. It looks like the 0.27mh inductor was changed to a 0.10mh and the 12 ohm resistor was changed, too, but I can't see the new value.


Thanks for the help.
Kurtis

 

[kurtisthesane]

Steve, I posted the schematics, any comments?

 

[kurtisthesane]

Bump