288 + 902 and 805B + MR94 measurements

[sfogg]

Here are a few different measurements of a couple of different drivers on a couple of different horns. All measured with pink noise.

This is a 288-8K on an 805B Multi-cell. The horn is rated to 500hz. The marker is at 300hz. On the top end this combo works very well up to 8kHz or 10kHz.

Shawn

[sfogg]

This is the exact same 288 but now on the *huge* MR-94 Mantaray CD horn. I haven't found great specs on this horn but I believe it is rated to 300hz. The scale is different then on the measurement above. Instead of going to 2kHz on the top of the measurement this one is to 1000hz for more resolution down low.

The marker is at 185hz on this one.

Shawn

[sfogg]

This is with the top end extended out to 10kHz to see the un-equalized top end response. The MR94 is a CD horn it would need EQ to be flat as can be seen in the measurement. The upside of the CD is the very even FR over the dispersion pattern of the horn.

[steamer]

Thanks Shawn,

Been curious how this horn measures out.Maybe I am early in my post but what about the 902?

Greg

[sfogg]

Expanded out to 20kHz, again with no EQ.

[sfogg]

This is the 902 on the MR-94 (using a 1.4" to 1" throat adapter) to see how low it can go on a suitable horn. Top end is 1000hz, marker is at 200hz.

[sfogg]

Extended out to 10kHz to see how the top end of the 902 is effected by the CD horn. Again no EQ. Marker at 250hz.

[sfogg]

For comparison sake this is an old measurement of the 902 on a 511B. Doesn't have the same loading down low but on-axis with no EQ it is flatter. On the 511B the FR changes over the horns dispersion though unlike on the CD horn.

[sfogg]

Finally found an older measurement I made of the 288-8K on the 805b showing the overall response of the driver/horn. You can really see how the CD MR-94 alters the response of the 288 compared to the 805B horn.

[steamer]

Shawn,

Thanks for the post,I was looking at the response of the 288 in the 805 and was surprised that up high in freq.there was very little roll off.I always thought the large format horns and drivers pooped out at 15k.From what I see it does really good up to about 17.5khz then rolls off.

Can you show how you have adjusted the response with your Behringer?

Very interesting what a CD horn does to the reponse!

Just currious.

Greg

[sfogg]

Greg,

"I was looking at the response of the 288 in the 805 and was surprised that up high in freq.there was very little roll off.I always thought the large format horns and drivers pooped out at 15k."

I don't think it gets up that high. They are good to around 10kHz then have a peak at around 11-12kHz then roll off from there. Run as a two way it was dark sounding compared to the 902. Some run them two way with EQ boosting the top end up, I have not tried that.

"Can you show how you have adjusted the response with your Behringer?"

You mean for the CD horn? I can't show that right at the moment as I have things sort of taken apart in my system. Should be pretty easy in the Behringers since they have the EQs and shelving filters.

"Very interesting what a CD horn does to the reponse!"

That is expected. The 511Bs (and most other non-CD horns) dispersion collapses as frequency increase to act as sort of like EQ built into the horn to try and keep the high flatter. The multi-cells were an attempt at increase dispersion up high before the CD horn was created. The 805 is basically are eight 500hz exponential horns built into an 4x2 array fed by one driver. In each horn as frequency increases they narrow in dispersion but since you have that occuring in 8 horns it still spreads the HF around more.

CDs keep their dispersion constant as frequency increases so the FR of the driver drops requiring EQ to keep them flat.

Shawn