291-16A's and 311-60 sound?

[Vinyljh]

Hello all,

Just quickly wired up my newly acquired 291-16A's and 311-60's with a set of JBL 130A's, I'm temporarily running them from 1200hz (JBL N1200) and up until I get a electronic crossover later this week, then I'll run them down to 500hz bi-amped. Eventually I'll get some 515's for the bottom.
One question for those who know these horns and drivers, they sound quite rolled off and not so clear and vivid as I expect these to sound. A little muted would be the best word to describe them compared to my small JBL 175's. I did turn the high frequency control to max on the crossovers and they seem volume matched to the 130A's. I know they don't go as high as small format drivers but I expected a bit more top. They also seem to suffer from quite a bit of "horn" sound and I don't mean in the good sense i.e. cupped hands syndrome. Is this the way these 311-60's sound? Does adding a tweeter remove some of this horn coloration?
The high frequency extension is not really my main complaint but the "horn" sound is as well as the lack of snap, sparkle and dynamics in the midrange I expect from a horn/compression driver.
I've heard 288's/515's really sing (the best I've ever heard really) but with tweaked crossovers using some eq, is that a requirement for these drivers/horns?
I look forward to your thoughts.

Best,
Vinyljh

[Fitts]

Hi, I have a pair of 311-60 horns with 291 alnico drivers, too. When I first got mine, one had some tar like crud in the throat of one driver so I opened it up and cleaned it out. I apparently opened it up way too much because after wards it was very dull sounding, had no highs and very little power compared to the other one that I had not messed with.

Bill at Great Plains explained that the alnico magnet had been partially demagnitized when I opened the driver the way I did. He remagnitized the unit and restored the sound.

I think your drivers may be suffering from the same problem. Loss of magnetizm is not just caused by dolts like me opening the driver wide open, it can be caused by rough handling, heat, age just to name some of the more common problems. Send the drivers to Bill for a remagnitization and I think you will be pleased with the results.

Regards,

[Vinyljh]

Hi Dave,

Thank you for your response. I've sent Bill @ GP a email.

Today I wired in the 500hz tube crossover and listened extensively, the mids definitely have a distorted quality, not a break up of any sort just a real grainy, veiled quality to them.

Any idea what a good working set of 291's extend to in the HF?

Best regards,
Vinyljh

[Fitts]

Good question. I think the 291 does start to roll off somewhere around 13K hz but the roll off is very gradual, tapering all the way to 20K hz. I don't think I would have described the sound of my demagnetized driver as grainy but vieled would have been a fair description. The demagnetized driver did suffer from a significant lack of HF. If I had to guess I would say that it cut off starting at about 8K hz and did nothing over 12K hz.

Regards,

[dennis gilliam]

Having run both 291's and 288's, you have to realize a 291 will never have that "sparkle" by comparison. The Symbiotik diaphragm just doesn't have the compliance for Hi-Fi.

The nice thing is a simple diaphragm change will fix all that. The bodies are identical.

291's are really great outdoors and at high levels. (essentially what they were built for) The music sounds lifelike, and a little EQ makes a world of difference. But there is a marked difference compared to a pair of 288's used indoors driven by a clean tube amp.

I could never warm up to the 311-series horns. Sure, they are the most rugged things, and probably won't ring at any SPL. A lot of pundits swear by them, but I just sell 'em off as fast as they come up. Like you, I think they are just dull sounding, no matter what driver blows through them. A MantaRay is a lot cheaper and sounds better to me.

DG

[Vinyljh]

Thanks guys for the info.
I solved one problem, the wires that lead from the back cover to the diaphragm were rubbing. Distortion is now gone and of course power handling is back.
They sound quite a bit better now but still have no real sparkle (big understatement!) or top end (of any real use), these need a tweeter without any doubt for real hi-fi use. I may just swap to 288 diaphragms and see how that sounds.
I'm quite sensitive to high frequency extension, I can still hear past 18.5khz , these 291's will never cut it for me.

Best,
Vinyljh

[Todd W. White]

Ray,

If you can give me a few more dimesnions of your floor plan, I can AcoustaCADD it for you and tell you exactly what you need.

Give me:

Width of seating.
Length of seating.
Height of ceiling and shape (flat, sloped, etc.).
Distance from front of platform to rear wall behind platform.

[AL-TEC]

Hi. The 291 drivers you have are great for outdoor rock concerts, or just loud PA. These can blow you away with high SPL! They will handle more power than the model 288 drivers with aluminum "music" diaphrams.....( Which can blow you away also!). This higher power handling of the 291 is due to the "Sybiotic" type diaphrams Altec put in the 291's for high powered use.. I have listened to a stereo concert Altec speaker system (multple Altec bass, multiple Altec HF drivers "Symbiotic" and horns) playing music back when not doing live outdoor or arena PA set-ups. This system with all "Symbiotic" horns really sounded harsh and "honky" to me with music playback in the shop. It hurt my ears! All the rock guys thought it was great?? I know different!
Altec model 291's, or the 288's with the all aluminum "music" diaphrams sound much better for music reproduction to my ears, not "honky"

I have Altec 311-90 horns with 288-C's with music diaphrams. These sound very good for music. This is especially if you are away from them a bit , or outside. If you have a really large listening room, these 291/288 alluminum diaphram driver/horns should not sound as you describe.Cross at 500 hz.


If you want a better high frequency sparkle in your music room, I would suggest model 511B horns with the 802 series drivers, or the latest from Bill at Great Plains the model 902 drivers with "Pascalite" diaphrams.

Happy listening with Altec's!

AL-TEC

[Vinyljh]

Hello AL-TEC,

Thank you for your comments and thoughts.
Last night I scraped the test system because it just wasn't doing it. I'll set it back up after I get some 288 diaphragms or maybe even later this week when I borrow a pair of JBL 2441 with Paragon horns from my friend
My room is medium sized at about 450-500 sq. ft. with nine foot ceilings, the speakers sit 8 feet off the back wall and I sit anywhere from six feet (not with this set up) to twelve feet away from my speakers.
These weren't really harsh sounding just dull on top. Cymbals and high hats just vanished after the initial strike, voices sounded hooded and I just felt like I had a cold with clogged ears. Switching back to a set of JBL 175's on 1200hz passive crossovers sounded way better than actively bi-amping with four tube mono amps. They don't have the weight in the midrange of the larger driver but they sound wide open.

Best,
Vinyljh

[raytclark]

If I can jump in on this discussion, I have just purchased vintage M94's w/ 291G's (4 ohm) to use indoors (church santuary 50'l x 100'w).

1. Would these drivers be better suited "as-is" for outdoor PA use or am I on the right track and ..

2. Would changing the symbiotic diaphram be the "best" solution by bumping these drivers into a "one horn" system vs. using the original diaphram and adding a second pair 1" tweeters to pick up the sparkle from say 14K up? (Let's just presume bi-amped crossover).

3. The M94's are long throw, should I look for the shorter versions (594's I think), (ie. is there a more better "coverage" in the first 50' with the shorter throat)?

(These will be used in a center cluster config., one for each half of the room, if that makes a difference).

I know these are preference questions. I just thought I would quiz "DG" (and others) since he has experience with both the 291/288's and the 311's/mantaray's. (The comment about the clean tube amp also got my attention).

Thanks in advance for all contributors, and also to Vinyljh for letting me squeze in on his post, I hoping this helps to clarify the abilities of the 288/291's.

Respectfully,
Ray Clark