Please help: crossover, horn, driver suggestions...

[altec210]

Hi,

I've been out of horns for a while, and I thought it would be nice to get back into it by joining your user board and getting a few ideas.

After great consideration and reading everything I could, I am ready to start gathering the parts for a horn system. I have settled on JBL 4560 cabs with my 416-8A drivers, and I'm looking at 203B horns with either 291 with a horn tweeter or possibly 288 without augmentation.

My questions are:

203B horn vs. 803B or 329A (smaller room, long and narrow, so I thought the 203 might be best...)

291 + Fostex type horn tweeter Vs. 288 without augmentation. If 288, what do YOU like best (C, G, K, etc.)?

I want to use just one amp so my family can use this too! Your thoughts on both the best crossover points (for either 2 or 3 way) and 1st, 2nd or 3rd order.

Thanks in advance for your thoughts and experience!

Michael

[bowtie427ss]

I have very little experience with the large format horns and drivers. Based on my limited knowledge i'd make these suggestions in order of priority as i see them.

1. immediately replace the 416's with 515's if your definitely going with bass horns.

2. i believe an 828 altec (A7) box will provide you with the same horn gain and response, plus the addition of some LF extension due to the A7's large bass reflex volume vs. the JBL 4560 box.

3. to my knowledge the 288G is as good as it gets for the large format drivers, and you will pay significantly for them. I would immediately have them sent to great plains for recharge and new phrams.

4. i think many will agree that with the above combination a 500hz 2nd order XO will work very nicely. Once they're in their locations where they will live you will likely need some padding on the horns, i prefer fixed resistors after using and L-pad to find the level of attenuation that best suits my ears.

This is just my .02 worth. i'm sure some will agree as much as others won't, after all it'd be a pretty boring world if we all liked exactly the same stuff.

[altec210]

Thanks for the great reply! I was hoping to hear that the 416 was close to the 515, but it sounds like that is not the case at all.

I do have some Altec 288s badged with IRC that were brought up to spec by Bill at Great Plains.
They are 16 ohms.

Is there any advantage to having all drivers at the same impedence? I have read that all should be the same, but I don't know if it really matters as long as the crossover settings are correct for the impedence.

Happy New Year!

[bowtie427ss]

Let me issue my standard disclaimer regarding my knowledge of Altec products. I've had a mild obsession with the professional line of Altec loudspeakers since my first exposure to them in the mid'70's. My statements and opinions here are based solely on my personal experiences, experiences shared by others, and from written/published catalogs, spec sheets, technical bullitens, white papers, and articles gleaned over the last 30+ years. I am NOT formally trained in acoustics or electronics. Take my comments and opinions with a grain of salt. There are others on this board who have been part of, or otherwise affiliated with Altec. Those forum members form a knowledge/info source that rivals any other source you'll find on this stuff................period.

AFIK, the 515 was designed/built to perform well in bass horn enclosures, and is the exclusive bass driver used in almost all of the systems using the large format horns/drivers.

I'm pretty sure that the 416's are best suited to a bass reflex type of enclosure, and are better suited for higher crossover frequencies in the 800-1200 hz region.

I'm sure others will chime in with accurate technical basis for the use of either woofer.

IMO as long compensation is made in the XO, there's no harm in using 16ohm HF with 8ohm LF, especially if using SS amplifiers. I think there's an advantage to using all 16 ohm drivers with many tube setups, but i don't know enough to comment further. Worthy of note "most" 515's are 16 ohm.

[boltupright]

The 515 will give you better midbass than a 416 would in a horn cabinet, the newer 515-8G is a very nice driver if it has the original cone, actually,,,original cones on any Altec woofer is paramount not only for collectability, but for best sonic performance as well, but if a recone is nessisary, try to find a NOS altec cone, it does make a difference IMHO.
Although I've had no experience trying a 3 way system with altec components, I've heard it said that less is more when dealing with a Voice of the theater A7 & that 2 way is the way to go, adding a super tweeter may cause some phasing issues.
I have a pair of Fostex lab series slot tweeters I wanted to try with the A7 but I have lost interest.

[Old Guy]

The JBL 4560 is louder (Just Big and Loud) than an A-7 but it's all above 150 HZ. You'll do better in your app with the A-7. I know this was already said, just reinforcing it.

[altec210]

That's unfortunate. I had a pair of 4560 cabs lined up for $50... I have all of the drivers and horns needed. I can also look for a nice pair of 515s at a good price. Does anyone know of a nice pair of unloaded A7 cabinets in the midwest?

Thanks for the continued replies on my topic!

Michael