Crossover recommendation needed

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I am building my 3 way openbaffle speakers and need advice on designing crossover, and may be a suitable tweeter (or super tweeter).

Current configuration is:
- Bass: Altec 416-8B (8 ohm 98db)
- Mid: Coral Flat 8a (8 ohm 96db)
- Tweeter: Saba greencone (5 ohm, unknown but more sensitive than Coral)

Attached are actual speaker (no tweeter attached yet) and planned crossover (with parts I got in hand). Among internet information, I am thinking to cross Altec up to 750Hz, and then Coral at around 7KHz or 10KHz.

This speaker will be used with tube amp 6C4C, supported by 02 Sub via B5 active crossover (can be config from 20Hz to 300Hz)

Any idea is welcome.
Thank you.


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A downward slope is always preferred :D:p;)

And you haven't watched the Sica page
Look at this LP 53x58.28/N20 TW

Yes, I saw this twitter. But it has 95 dB of pressure, and another 1-2 dB will take over the crossover.
"A downward slope is always preferred " - This will happen when measuring absolutely even (from 1 meter) loudspeakers, when it is measured from 3-4 meters.
Thanks for your recommendations.

Actually I want to use the simple crossover as much as I can. From beginning, I use FAST configuration, directly connect the tube amp to Coral and 0.4uF capacitor series with the tweeter.
The sound is good and nature, but it lack of mid low when listening male voice, that why Altec is there.

I don't know much about crossover design, so I would be glad if you can suggest crossover with schema/topo with some example value of parts.

Regarding the tweeter, I am thinking of some AMT tweeter like Mundorf or cheaper like Dayton, is it suitable to my current speaker?
i would put the crossover between the coral and the 416 way lower (like 200-300Hz) and have a WAW system with it. The coral can be used to 50Hz, and the 416 also like a lower crossover more. Like this the crossover band is alo outside the sensitive crossband where the crossover may disturb the most. i included a very fast sketch of how i should do it with this drivers (still needs a lot of finetuning, to start with the actual measured data from the drivers as this is on generic drivers with adapted sensivity...


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Hi Bitinhvi,

sorry, but my 2cents: Guesswork will not lead you anywhere. You might simulate, you must measure, you should hear...
You´ve invested a decent amount in drivers, get yourself a UMIK and REW and start to make measurements. You´ll soon find out what works and what works not.
For example single L before the Altec will not be enough, you´ll need to control the rising mids. Single C before the Coral is useless, as the response comes back at FS. Might be OK for low level listening, but then you can omit the C at all...
Same with tweeters, single C will work only with FS control by LCR parallel (or ferrofluid...).
With your concept, may I ask what reason is behind the ears above the Coral? However, I´m with waxx, try a WAW first and think about the tweeter later. If the Coral is still good, it will have a lot of treble.
If I was you, I would first determine the efficiency levels of the drivers at the edge of the baffle effect, where the 6-dB OB slope becomes steeper. You´ll have first to find the correct L value for the Altec which turns the 6 dB slope even, then you have your reference level. After that, check at which frequency the Coral in OB is also at this level, you might find out that this point is higher than 200 Hz.

Than continue with the crossover by adding parallel C to the Altec, series C to the Coral and parallel LCR to the Coral.

After this, you may start to think about correction of the Corals rising response, but if you are that far, listen long and play with values for amplifier match and taste.

You´ll have a lot to do until it makes sense to think about the tweeter...

Best regards

Thanks Seebee, Waxx and Mattes for your supporting comments.
The reason for this thread is to shorten lead time, I hope getting advice from someone that experiened with the Altec.
But I guess I have to follow tradditional way as Mattes comment.
I do have a Dayton mic and REW software. Mattes helped me to know starting point.

@Mattes, ears on top of baffles are just for fun with my kids. It make speaker looks like a Rabbit and a Cat. Tweeters might be mounted on it later, but my be I need to add some extra arms to hold the tweeters.

Until today I had chance to measure my drivers separately to get your help on crossover design for my speaker.

I measure using REW as attached picture, inorder to find crossover point.

Should I cross the Altec at 500Hz, or 300Hz? and let the Coral run fullrange, or better also cross the Coral at the crossover point?

It would be good to me if you can also recommend crossover schema with part value.

Regarding tweeter, I plan to have Fostex FT17H with 0.68uF to handle from 14KHz upward.

Many thanks.


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Post here the *.FRD and *.ZMA file exported from REW.
The measurements ware made with the speakers in final box or in free air?
If you can provide the .FRD and .ZMA files in final box for the speakers and for tweeter to than can be made easy a simulation for crossover.
Hi Sesebe,

Thank you for your response.

Drivers are mounted on the openbaffle that is intentionally used as final speaker.

Sorry I am not familiar with REW, could you check if attached file is the needed file? I have to zip it as forum not allow to attach FRQ file.

I don't know how to export .ZMA file though.


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