Altec Build

[jeffjmr]

I am the fortunate owner of 4 each 288B's and 515's, and two N500C's.

At this point I am not sure I have the room to utilize a 210-like speaker, so am thinking of making two sets of two-ways with one each HF and LF (need two more x-overs, of course), or selling the extra drivers to finance the refurb, cabinets and HF horns.

I intend to send the 288s into GPA for the mod and new diaphragm's, and two of the 515s as well as they have some rips in the cones.

Here are my challenges for which I could use some advice; do I stick with 24 ohm diaphragms or opt for 16 or even 8?

Do I splurge and buy some A7 cabinets off eBay or are plans available to build something better? And what HF horns would I be forced to use in the case of the A7 cabs, as 1.4" horns seem to be in shorter supply than the 1" models. Home use but I tend to play orchestral rock and pipe organ music at relatively high levels.

Any advice is greatly appreciated.

Jeff

[Altec Best]

Here are my challenges for which I could use some advice; do I stick with 24 ohm diaphragms or opt for 16 or even 8?

Hi Jeff ! This will depend on your amplifiers.What will you be using and what are the ratings on them ? The 24 ohm aren't used much anymore mostly 8,16 ohm.Also the biggest factor here is what size,kind of (Hardwood,Concrete) room are these speakers to be used in ? All these factors will have an effect on the quality of sound they will produce. But first size,is there any limitations on the actual size of the LF enclosures you can use WAF,etc, ? In my personal Opinion any of the large format drivers should use dual woofers.The 288's are a lot more efficient than the 515's if single woofers are used, 288 will have to be padded down ! Or it will sound very bass shy (All Mid-HF)

[jeffjmr]

Thanks Altec Best.

These are for home use, conventional stick and drywall. A relatively large room now, 16x24 and 20 foot ceiling open on one end to the rest of the house, but will likely end up in a smaller family room in a town house.

Currently a Yamaha HTR-5590, 100W/channel but I hope some SET's are in my near future. These components came from a pair of A4's handed over to me by a friend in NY. The cabinets were ruined in a flood. I mistakenly passed on the HF horns which included the y-adapter to handle the pair of 288s, as they would not fit in my car. Finding the larger port horns now is difficult. 'DOH!

I was hoping to sell two each of the 288s and 515s to finance the rest of the build, but I am a fan of bass (love those 32 and 64 foot pipes) though I'll keep my Velodyne DD-15. So if you say I need both 515s, I trust you though that will challenge me as far as cabinet size is concerned. Need to decide whether to build or buy cabinets, too.

Jeff

[Panomaniac]

I don't see any reason to stay with 24 ohm if your changing them. 16 is nice as it can allow a bit more room for EQ tricks in the crossover. Not a big deal, tho.

[Altec Best]

Your Welcome !

OK first in general if your using Tube amps go with 16 ohm and SS use 8 ohm.You just have to check the amp. McIntosh amps, some have multiple taps for different Resistance, 16/8/4/1 etc....

You can get by using a single woofer with a 288 but you will have to do some crossover work to pad down the 288,say 7-10 db,this is were you will have to tweak to get the right sound for you.So it could be more or less than 7-10.This is were your preference comes in.You like bass and so do I.I'm building a dual woofer project now that I need to get my butt in gear on now ! As GM has recently told me it should be a Stellar system. That gave me some more motivation.It is just hard working full time,I'm not retired yet.Jeff 16x24 is not large for those speakers.My room is a little bigger but don't have the opening in the ceiling.Most speakers can't play those very low or lowest notes from a pipe organ anyway.If the lower bass is what your looking for you would probably like the 416's better than the 515's as they will go a little lower than the 515's. What 515 model do you have 515,515B,515C,etc, ?

[Old Guy]

OK first in general if your using Tube amps go with 16 ohm and SS use 8 ohm.

Way overgeneralized AB. That's the speaker 101 answer.

As Pano notes, using a 16 fram on SS has some options.

Personally prefer it, as a 16 ohm HF with parallel resistance will show a MUCH flatter impedance curve to the crossove than an 8 ohm fram.

Due to the lower efficiency of woofs you don't wanna do that without power to waste.

Even with active xovers, presenting a flatter impedance to the amp is gonna result in a more uniform power draw.

It really comes down to how much you can expand your brain before it blows out, as there is virtually an infinite amount of info.

Also, even if you wanna use SS amps...what about the crossovers? If you already have 16 ohm xovers 8 ohm frams are counter productive.

The simple answer is there are no simple answers...

[Altec Best]

Yes it is OG. I said in general (Short Answer) as you say we could go on for hours ! Not Gospel ! He says he may get tubes I think 16 is the best option IMO.

what about the crossovers?

From the sounds of it,he maybe building his own cabs so a custom/active xo will most likely be used anyway,I'm not sure if he will be able to use those N500C's,dunno ?

FWIW Crossovers aren't my strong point !! Thanks Again Pano !!

[jeffjmr]

I knew it was complicated from the gitgo, that's why I'm here. I don't want you to build them for me, but I am appreciative of shared collective wisdom to get me there quicker and without lots of wasted experimentation (spelled $$$).

I would like to stick with the N500s since I already have them, but if a significant performance improvement can be had with others I'm open.

AB, the woofers are straight 515s, but will go to GPA for remag and any other useful mods that won't break the bank.

Old Guy, what is meant by parallel resistance?

I won't need the 515s to go too low as I will keep my Velodyne DD-15.

I'm leaning towards building 817 cabs. But drawing a blank on HF horns. Will mating the 288s to 511 or 811 horns with the adapters ruin their response or help with the apparent need for some attenuation anyway?

Thanks again, all.
Jeff

[Altec Best]

Well if you want to use the N500 crossovers then you will have to use a 500 Hz horn.Like a 805,1005,1505 you don't want to use a adapter like the 21216 going from large format into a 1" throat.Yes it could ruin your response but more importantly your diaphragms.If you used a small format driver with that adapter to a large format horn that's OK.You can get creative and get a 511B turn it into a 511E but you need a good aluminum welder for that because you have to cut the throat down to 1.4" and re-weld the mounting flange.You need to get your horns first before you know what crossovers and such you will be using.Bill had a couple pairs of them that were done like that they just needed to be damped.This is what they looked like.

[jeffjmr]

XX05 horns are nearly impossible to find at a decent price.
Could 811Bs be modified as the 511s above? Does the throat expand linearly from the 1" so that it is a simple matter of cutting the flange off far enough up at which point it is 1.4"? And would the then 811"E" work with the 288s and N500s?

Alternatively, is there enough "meat" at the 511 throat to bore it out to 1.4 as opposed to cutting and welding?