Suitable midrange cone, for bandpass mid in Unity horn.

[Sheldon]

I toasted my external sound card, so I haven't made any impedance measurements - though I guess I could use the laptop's internal card. I have taken quite a few FR measurements with the DEQX. I see very little difference with or without the foam, other than the modest roll off above about 7-10k.

Sheldon

[JLH]

The thing you need to know is when you load a 91dB mid into a Unity you pick up around 10dB. How much you actually pick up is determined by how strong a motor the mid has. This partly explains why the Faital 3FE20 has about 3dB more sensitivty in my models than the Misco JC5RTF-B. In addition, due to the increased loading, the Fs will drop too. A weaker motor will drop lower in frequency than a strong motor.

[Sheldon]

Hmm, so if the Faital is 3dB more than the Unity Misco, then might get by with two after all? Catch is that tweeter is 8 Ohm, so parallel/series of 4 makes it easier for the crossover (if passive).

Sheldon

[JLH]

Originally Posted by Sheldon

Hmm, so if the Faital is 3dB more than the Unity Misco, then might get by with two after all? Catch is that tweeter is 8 Ohm, so parallel/series of 4 makes it easier for the crossover (if passive).

Sheldon

True. One of the things that can be tough is keeping the impedance of a Unity/Synergy up above 4 ohms. If you look at the Danley site, you'll see most of the Synergy horns are rated at 4 ohms. This isn't just to pull more power from pro sound amps, it because thats the way most of them end up by using 8 ohm speakers. The model I'm working on for the 3FE20 is around 7 ohms, which is better than most of my other models.

[JLH]

Looking over all the mids that Misco has, these are the ones that could work. My eye tends to favor the JC4C. All of these mids would have to be sealed up. After thinking about it, I'm not sure if the 3FE20 will work out. Sure, the Fs can be pushed up to 591Hz (per John) in free air, but can we keep it up there when mounted on the horn? That seems to be the million dollar question.

[JLH]

This is what I got so far on the 3FE20 Akabak script. See the plots for power response, impedance, and phase.

[JLH]

Here are the results of the 3-way Synergy using the 3FE20 and the Eminence LA8-CNMB. Funny thing is the phase is flatter than the 2-way.

[Antripodean]

Seriously impressed by your work JLH! As an owner of an original Unity Horn I can say the effort you are putting into this will definitely be worthwhile (as you would already know). Seems I need to build another to do a comparison

[SunRa]

It really looks great John, I have to start save my pennies if this turns into a kit..

I must have missed that discussion but are there any specific reasons for using the Eminence LA8-CNMB? and not other 8" driver from b&c, beyma, bms, 18sound?

[Marcello]

The KC4C-8C looking very good on a horn, flat acoustic power from 400 to 1400Hz.
It also easy to seal the frame on this driver, because it`s nog rugged.

It looks like to me you have to aim for flat pressure and not for flat acoustic power. The design reference is flat on-axis?

I send misco a couple off questions and waiting for a reply.