Coral 25L-25B/Altec 808-8B Speaker

[dubwicht]

I aquired the above combination for $100 at a shop on the weekend and would like make a two way mono speaker. Will this combination actually work? I have found the design specs for the Coral driver but cannot find the specs for the Altec. I ordered an 811B horn for the driver today.

Has anyone experimented with a horn loading of this woofer? Evidently Coral calls for a 65liter sealed box. However, I assume that a sealed box would not keep up with this driver at 109 db sensitivity. The driver specs are as follows:

12L-25B Paper cone 12" bass driver,
94 dB sensitivity,
lineair upto 3kHz
Re=6.6 Ohm,
Fs=44 Hz,
Qms=11.8,
Qes=0.62,
Qts=0.6,
Mms=40 g,
Cms=0.33 mm/N,
Vas=110 L,
BxL= 10.8 N/A,
L1k=2.6 mH,
60W

Also wondering where to start designing a crossover. I can solder them up from schematics but have never designed one for myself. Does anyone offer a design for pay service?

Cheers, Doug

[planet10]

Pictures?

dave

[dubwicht]

Hello Dave. I was at your DIY festival a few years ago with my wife and had a great time. Just recently got back into building speakers and electronic stuff.

I am working on a three way speaker, a Pete Millett tube preamplifier and this high efficiency speaker for my old preamplifier (just ordered new tubes).

Here are a couple of photos of the Coral driver. Do you require a photo of the Altec driver?

Thanks for the help!

[planet10]

I've had some of the 10" version of those and they are very similar to some Foster 12s i have a QUANTITY of... other than stuffing them into a big sealed or aperiodic box, they'd really need to be measured to figure out a box...

dave

[GM]

Originally Posted by dubwicht

........but cannot find the specs for the Altec. I ordered an 811B horn for the driver today.

The 808-8B is a MI horn driver, so assuming it still has its original diaphragm or proper replacement it plays loud and a bit harsh with a rolled off top end: 808-8B COMPRESSION DRIVER

Replacing it with the 802-8G's diaphragm as used in the Model 19 is de riguer for HIFI/HT. Shelving it enough to mate up to a relatively low efficiency woofer will eat up most of its dynamic headroom though. Regardless, the 811's polar response lines up with a 12" in the ~1350-1500 Hz BW depending on woofer design plus it's high enough to eliminate its horn 'honk'. That, or XO it around 800 Hz and use CD horn EQ.

If the Coral is ~flat to ~3 kHz, then there's nothing to horn load except down low, so would be huge.

GM

[dubwicht]

Thanks Dave. Is this a decent driver in your opinion or should I look for an Altec or other driver instead? I would hate to spend the money and time on a cabinet and not like the performance.

[dubwicht]

I looked for a diphragm for he 802-8G and it appears to be the same as the 808-8A at least from this site.

Altec Replacement Diaphragms - Sound Speaker Repair

What should I look for in the diphragm? Is it aluminum? Cheers, Doug

[GM]

Those are Radian or some other generic replacement. OK for PA, but for HIFI you want an original #34647 from GPA (heed note #5): Great Plains Audio: Parts We Have Available

GM

[dubwicht]

I will check it out. Thanks!

[dubwicht]

Talked to Bill at Great Plains and he is going to set me up with a 3127 driver and I will build a 3 cubic foot enclosure. They are almost finished a 1500 crossover that works with this combination and will be finished testing on Friday. Add the 34647 diaphragm and I am all set. Thank you for the help! Cheers, Doug