Crossover calculations (e.g., ESS Heil AMT)

[cdfr]

I have some difficulties in figuring out how to calculate the frequency cut off and the attenuation of the two cross over attached.
Those are from ESS AMT Monitors.
The figure 1 (filter 1) is copied from an ESS schematic.
The figure 2 (filter 2) is what I drew from my ESS AMT 1E monitor from 1994. I do not have a the values for the inductances L1 & L2.
In both cases I believe that the crossover frequency is ~1000Hz

Currently I use the figure 2 filter on my AMT 1E on which I have added 1 Heil (so I have two Heil per speaker in parallel). To compensate for the impedance change, I added in series one resistor of 1.8 Ohms. Each Heil being ~3.5 Ohms, I end up with 1.8 + 3.5/2 = ~ 3.6 Ohms. It sounds good that way.

Now I am using that same filter figure 2 on a planar speaker I am building with the Heils being the treble. Same conditions the filter works well.
However I am not sure of what I am doing (as you can notice ), The two Heils present together with the resistor present an impedance of 3.6 Ohms to the filter (Not sure what I do is correct or the best solution) and my flat pannel present an impedance of 7.3 Ohms. In both cases the impedance is resistive only.

I would like to modify filter 2, to have the crossover frequency at 2400 Hz. This is why I am asking for help in how to make the calculations.

In a second pass I would like to try filter 1 on the 2 Heil set up &flat pannel and cross over at 2400Hz. Same issue what re the formulas to use to calculate the filter,

Any help that can point me in the right direction is welcomed.

[baddow]

Hi,

did you manage to figure out your crossover? I'd love to help out, but don't know enough about the electronics here.

Just curious because I'm also finishing up a pair of speakers using an AMT1 as tweeter and a pair of 18W/8545's per side. I got impatient and just set it up with an off the rack crossover, but of course the tweeters need serious attenuation before this is even close to balanced and its currently barely listenable.

Thanks

Olaf

[cdfr]

Hi Baddow, I did not make much progress there. I am working blind using a spice freeware and fidling with values, but not making real calculations.

How about you?

[baddow]

Hi cdfr

I'm in the same boat, haven't made any progress, but its due to lack of trying. (new house, new job etc - have kept me busy).

That being said, I've changing directions a bit. pairing the AMT1 with my scanspeaks is a real problem due to massive differences in efficiency. my research shows the Heil to about 102 db/w, while even the dual scanspeaks are about 91 db. plus mounting the heil on top was just difficult. and these drivers are just too expensive to use 8-10 per side.

So i ordered an SS ring radiator tweeter and will finish this project with two drivers that are closely matched. and....it leaves me with a spare set of AMT's.

So....that project will likely be a set of large monitors. What i'm considering is a up to 8 mid range drivers per side, to somewhat match the efficiency. (I have a large living room that would work for this.) Obviously cheaper drivers (and did feel guilty about matching something cheap to such a great tweeter).

I'll keep you posted when I get going on this.

Cheers

[HARDGRAVES]

What program are you using for your schematics?
Thanks

[cdfr]

I am using 5Spice (5Spice circuit analysis and simulation software homepage - download your free copy now).

Baddow, you can always use attenuation to match the efficiency of your LF drivers.
I think that the best configuration would be to have a LF driver (or 2) and a Medium going up to 1500Hz. I found that the Heil does not sound so good between 1000 & 1500Hz.

[Psychobiker]

I seriously recommend you google :
'Pspsice student'. PM me if you want a bit of a hand, I know it backwards from hours and hours of simulation in college!!

Was used here :

Crossing Over...

[baddow]

Hi cdfr. Actually I'll be using an active crossover, with two small Crown amps, so will have full control.

However, when I built the first version of the speaker, it was with two SS mid woofers about 87 db and the Heil. I had put about 18 db of attenuation on the heil to balance the sound. I'm sure someone will disagree with this and maybe the XO wasn't accurate on this. Its also possible that my amps were mismatched for this application. (I didn't have the Crown's with volume control at that time.

At that point the Heil lost a lot of its dynamics. Worse was background or line level noise coming through. so I decided it'd like to increase the efficiency of the LF to get at least somewhat close.

I played with different XO points, but there was so much going on (noise, HF too loud) that it was hard to tell. Then I bought a house and renovated.....so that project got put on hold.

Life is interferring with my toys again. <sigh>