Small format MantaRay horns...finally!

[RonSSS]

Hey giys,

Haven't been here for quite some time.
I finally found a pair of small format MantaRay horns.....MR994's on Ebay. Haden't checked there in months either, but found a pair and bought them.

Ever since hearing the Mant horns in my 904 duplexes, I've liked the sound. So thought these would be interesting to hear in my model 19's.

Should have them in about a week, and I'll hook em up and let you know what I think.

I don't think they will fit directly in the cabs, but with a simple mod, I think they will.

I've never been totally impressed with the 811 horn.

My 19's BTW have the ferrite 902-8A drivers (the best I think) and the 416-8C ferrite woofs (not the best I think). Still need to finish re-coning my 416-8B for the bottom end.

Ron

[RonSSS]

Forgive my spelling!

Hi Mike!

Ron

[Mike Gibson]

Howdy Ron and welcome back to the land of the nearly living

[joyspring]

RonSS:

The MR994 will not be a direct swap with the 811Bs; you must use a different crossover or line-level equalisation with the constant-directivity horn.

Though I do not have the specs on the 902-8A nor the specs/polar plots on the MR994, provided that it has good directivity control and even power response through its rated frequency range, the MR994/902-8A on-axis frequency response will mirror that of the 902-8A's plane wave response. Most likely it falls at an approx. -6 dB/octave rate above 6-8 khz and you must compensate for this to achieve a flat on-axis response.

BobR

[RonSSS]

Good info Bob
I have a few spare M19 crossovers to play with.
These are the dual shelving variety.
We will freq response plots and see how it looks.
I'll report back whe we do that.

Ron

[cclark65]

You could use a regular equalizer with the high end boosted up to make up the difference. I have to do that with my PA since I don't have CD-EQ on my crossover.

[RonSSS]

The MR994A's showed up yesterday. Pristine condition. Another successful ebay purchase.

So, I didn't do my homework very well. these are 500hz horns, and no way will they fit in a model 19 cab. Way too big! Unless I were to build new tops......

Anyway, looking forward to trying them just sitting on top.

Anyone know where I could find a spec dheet for these?

Ron

[bfish]

Hi, Ron,

There's an FR/Z plot for the MR994A/909 at;

http://alteclansingunofficial.nlenet...909-8AData.pdf

Never seen any polar plots for the 994s, but I think all the MRs are fairly predictable ITR, you could expect 90x40, no more, no less. The only difference on the linked FR/Z plot from your 902s would be if you have the std. 34647 'phragms in them, as the plots are for the 26420s, but the mag. structure's of 902s and 909s are the same. As mentioned earlier, you'll need some CD horn EQ to achieve flat response. The Altec passive XO used in their M500 systems has this EQ (switchable) specifically for the MR994A/909, and there were plug-ins available specifically for them for Altec 1631 and 32 electronic XOs. Many other brands of electronic XOs have CD EQ functions of a more generic nature as well. I've got a pair of M500s flown in a friend's very reflective garage, and we prefer their EQ switched off.....so hook 'em up, and EQ to your room/taste. If you're driving them with tubes, the extra harmonics may "fill in the gap" where the 994s response starts to fall....or vice-versa....harmonics are pretty much all that's in that range anyway.

If you should ever decide you prefer your 811s, and want to sell the MR994As, send me a PM. I've got an empty pair of M500 cabs waiting (patiently) for some in storage.

[RonSSS]

Well,
I hooked them up just sitting on top of the model 19's but drove them from the model 19 crossover. I put a pair of 902-8A drivers on them.

I like the sound! I had to tweak the HF up a bit, but to my ears, there is no aparrent loss in HF response.
The model 19 crosses over at 1200hz, so the 500hz range is not an issue.

Immediatly apparent that these don't beam. The sweet spot is much larger than with the 811's. Very smooth response.

I do note a bit of hollowness, but I believe that is due to the fact that these are either some sort of plastic or fiberglass, and the horn body could use some damping on the outsides.

These will not work in the model 19's for sure. And I'm not going to build new tops for them. But I can see a new project down the road. Maybe a larger model 19 type of clone. I have a spare pair of 416-8B's, spare model 19 crossovers and the 902-8A or 802-8G HF drivers.

Glad I got these!

Ron

[yup]

Ron,
Would you attribute the hollowness to the plastic material (GE Noryl), the low frequency loading of the Mantarays (supposedly not as good as the sectoral - granted it would be below the 1200hz crossover you used, but still noticable acoustic energy there) , or maybe just a crossover that needed more work?

I am very interested to hear your opinion (and came very close to buying these right before you did...) Everyone has such a strong opinion on the CD vs. Sectoral topic and now you have some very applicable experience.

If best overall sound (in the sweet spot) was the main requirement, which would you prefer?

Thanks,
Jeff