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Crossover Assistance with Eminence Speakers

Atomic007

Atomic007

New Member
I am in the process of renovating a 1958 HiFi Console. The internals are shot so I am upgrading with all new components. I have chosen replacement speakers, which are similar to the old ones, just much better.
The old speakers each have a capacitor for crossover. I have emailed Eminence to find out what capacitor or
crossover to use, but of course they are closed down currently and have a generic email response.
The speakers are both 8 ohm and the amp I'm using is 4 ohm. Here's what I'm doing with pictures for reference and inspiration. I would be really happy if someone can help me. Thank you.

The speakers I'm using are: Eminence Kappa 12-A Full Range 12" 8 ohm
Eminence APT-30 Supertweeter 8 ohm

Thanks for your help.
 

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Unfortunately there's no chance of anyone designing a proper crossover for two random drivers via forum posts. I suggest that you keep it very simple and just use a capacitor in series with the tweeter. At least it will work and will prevent damage to the tweeter. Choose the value of the capacitor by ear. Start with about 2uF and try larger values up to maybe 8uF. It's a pretty crude approach but will get you up and running. You can always work on something more sophisticated later if you have the means/knowledge/inclination.
 
Pick a different tweeter.

Kappa 12A has a sensitivity of 100db.

APT-30 has a sensitivity of 93db, exacerbated by a fairly steep 10db roll-off above 10khz.

Tweeter should be AT LEAST equal in sensitivity, higher is better.
 
Yes.. and agree with the prior post, if you cap the tweeters, you should be good.

As for the amplifier, you stated it is 4 ohms, I am not sure how you got that spec? Or is that the original spec for the OEM cabinet installs?

Is there a schematic or flow diagram somewhere in the cabinetry?
 
bowtie427ss said:
Pick a different tweeter.

Kappa 12A has a sensitivity of 100db.

APT-30 has a sensitivity of 93db, exacerbated by a fairly steep 10db roll-off above 10khz.

Tweeter should be AT LEAST equal in sensitivity, higher is better.
Click to expand...
Yes, I wondered about the relative sensitivities of the two drivers too - but was too lazy to look it up :oops:.
Besides, I didn't want to worry the OP with yet another complication :)
 
bowtie427ss said:
Pick a different tweeter.

Kappa 12A has a sensitivity of 100db.

APT-30 has a sensitivity of 93db, exacerbated by a fairly steep 10db roll-off above 10khz.

Tweeter should be AT LEAST equal in sensitivity, higher is better.
Click to expand...
That's absolutely incorrect. A woofer should be 3-6 db more sensitive to account for baffle step losses.
 
Would this tweeter be a better choice? Or does someone have a recommendation?
 

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I’m going to side with Bowtie on this one. :)

It’s a lot easier to attenuate a hotter tweeter than it is a hotter woofer. Whether via resistors, an lpad, pot or whatever.
 
OP, what kind of tweeter did the cabs have originally? Like what kind of opening.

Are you trying to find something to fit an existing opening in the baffle, or are you going to mod the baffles to fit your new drivers?
 
Atomic007 said:
I'm using all new equipment, including the amp which is 4 ohms
Click to expand...
A four ohm amp? Are you sure about that? In the solid-state world there's really no such thing as a four ohm amp. "Four ohms" would be the minimum impedance the amp could tolerate safely, but the amp wouldn't have to be used with a four ohm load.
In the valve world, a "four ohm" amp would make more sense, but there are usually taps for 8 ohms too.
What amp do you have?
 
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elitopus said:
OP, what kind of tweeter did the cabs have originally? Like what kind of opening.
Click to expand...

The new speakers are very similar in size as the old ones from 1958. The originals are Jensen. The 12" has no cap. The mid/tweeter does.
 

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As I have researched through the interwebs, I have found several vintage console restorations/mods/refurbs, whatever. It seems most have chosen to just set an already enclosed new-built speaker into the cabinet and called it good. I would prefer to replace the speakers in such a way as to maintain the original design. I know slapping a couple bookshelf speakers inside the cab would be a lot simpler, but this is kinda what I have my heart set on, so to speak. When I'm finished, I want the unit to look like it's all original. But, work and sound like new. Kind of like taking an old Mustang that looks original on the outside, but has an updated drivetrain and new engine underneath. I'm hoping someone knowledgeable will catch the spirit of this and be able to help. I found a guy who does this for a living at atxrecordplayers.com and his work is stellar. I would like to do mine in the same fashion. He isn't willing to share any secrets of the rebuilds, which I completely understand.
 
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Atomic007 said:
As I have researched through the interwebs I have found several vintage console restorations/mods/refurbs, whatever. It seems most have chosen to just set an already enclosed new-built speaker into the cabinet and called it good. I would prefer to replace the speakers in such a way as to maintain the original design. I know slapping a couple bookshelf speakers inside the cab would be a lot simpler, but this is kinda what I have my heart set on, so to speak.
Click to expand...

OK.. understanding your flow..and approach to the OEM spec :)
 
If I might add...
I've built many systems in cars over the years. Always high-power component systems with individual drivers, subs and amps. It's a different game because most components come as kits with included 3-way crossovers and Class D mono-blocks for subs with built in crossovers. It's really plug and play for the most part. I'm in a whole new realm here with home stereo, and that's what brought me to this forum. I'm not going for an Audiophile system here, that's not really the goal. I just want it to sound nice and enjoy it. So thank you for your interest and help. Its appreciated.

I've included spec sheets this time so you don't have to look it up.
 

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roxoncontac said:
That's absolutely incorrect. A woofer should be 3-6 db more sensitive to account for baffle step losses.
Click to expand...

Yes, IF it was in a narrow-baffle speaker cabinet (less than 2' wide).

However- this is in a console. Much more baffle area.

I don't think you'd need enough baffle-step-compensation, in a console, to make up for 7dB of sensitivity difference.

IME and IMHO- the APT80 would be a better choice, than the APT30 for a supertweeter to use with that 12" driver. It's higher quality all around. Even after you compensate for the excessive low end (it has a broad peak between about 3K and 10K), you should still have enough output to work with that woofer. You may need to use a notch filter in series with the woofer to compensate for a high-end peak in its response just before rolloff (a 1mH coil, 40uf cap and 4 ohm resistor in parallel, should be pretty close), and effectively cross the tweeter over higher than it would theoretically be if the tweeter response was flat (if it didn't have the peak between 4K and 10K- a 2.2uf cap- maybe slightly smaller- probably will work to cut down that peak and blend with the woofer). If you do that, the levels should match pretty well, it looks like.

Regards,
Gordon.
 
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The woofer is designed to have a compression driver fire through it. That said, like Gordon said, the APT-80 would be a better match.

Parts express has a Dayton crossover, already assembled, 2nd order L-R, (12 db/octave), crosses at 3.5kHz, that would be a very good starting point.

I used that one, years ago, with a pair of QWTL speakers using Beta 10CX speakers, with an Eminence compression driver firing through the centre.
 
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