Switch to full style
A place to discuss member's DIY audio projects & post pictures/schematics. NOTE: There is a limit of 2MB per attachment, and a maximum of 3 attachments per message. If you need to post more than 3 attachments, just add another message.
Post a reply

Re: New Project

July 29th, 2020, 9:32 am

For the horns and compression drivers, ideally you will crossover about 1 octave above the low end of FR. Look at the specs of Radian 850P. FR is from 500Hz but the min. Recommend crossover point is 700Hz. I would move XO closer to 1kHz but not quite. In a multi-way active system, you need to keep each driver FR within a decade. If the scanspeak is crossed over at 80Hz, you need to limit it to under 800Hz. If you sub can handle it , operate the scanspeak drivers between about 100/120 - 900-1000Hz.

Re: New Project

July 29th, 2020, 3:25 pm

brombo wrote:What about horn loading the scan speak driver. I think about the old Altec Voice of the Theater configuration except that the driver would be in a sealed box and not ported since the subwoofer would supply the low bass.

David is right, look at vintage bass drivers to match the compression drivers.

VOTT’s bass horn loading is minimal.
Vintage Altec drivers are about 100dB efficient which matches the compression drivers within 3-4dB.

Re: New Project

July 29th, 2020, 6:33 pm

Per your suggestion I am now looking at this driver for mid-bass:


Back in the 70's I build a bass reflex system with an Altec 15 inch (voice of the theater) woofer, Electro Voice diffraction horn mid range, and Electro Voice T35 diffraction horn tweeter. It was tri-amped using a homemade analog electronic crossover (opamps). The power amps were kits from Southwest Technical Products including a class-A headphone amp (solid state) for the tweeter.

Re: New Project - Eminence Delta Pro 12A

August 3rd, 2020, 5:22 pm

If you are interested, I was just getting ready to list a pair of Eminence Delta Pro 12-A.

While they are not the king of low-end extension, that should not be an issue if you plan on using a subwoofer.

They're usable frequency range per Eminence is 50hz - 4.5Khz, but I would not advise using them above 2.0Khz < -even then that should be plenty of overlap between the other drivers in your system.

They have a rated sensitivity of 99.2db.

I've only mounted mine for testing - but ended up going in a different direction with my build.

They sell new for $140 each. I was thinking of asking $150 for my pair. I have the original packaging, etc.

Re: New Project

August 3rd, 2020, 10:27 pm

Would you be interested in trading your two woofers for two of these -

Scanspeak M22WSR-45 8" Paper Cone Shielded Woofer With Truncated Frame 8 Ohm

Re: New Project

August 4th, 2020, 8:43 am

brombo wrote:Would you be interested in trading your two woofers for two of these -

Scanspeak M22WSR-45 8" Paper Cone Shielded Woofer With Truncated Frame 8 Ohm


Unfortunately, I got my hand already in too many projects. I know Parts Express has a pretty decent return policy - have you considered returning those?

I might have considered a partial trade, but I find truncated frames to be too challenging for me to flush mount.


Re: New Project

August 4th, 2020, 9:31 am

A partial trade would be OK. The Scan Speak woofers and how much cash?
Post a reply