"Crossover Design for New Project"

[Steve Mac]

I'm a big fan of active EQ...not passive so I'm not much help.
I am in somewhat a similar boat that I am beginning to put another system together
not too different than yours. Except I like simpler projects...yours is a beatiful but
could be a real gorilla in tweaking...but no doubt it might be worth it.

I'm thinking 511E but with GPA288H drivers...the high end is better methinks
so I do not need the ev tweeters...though gm may add that the ev tweeters bandwidth
may be more appropriate. Still I truly believe the fewer number of transducers...the better.
I'm thinking of the alnico gpa 416 speakers...I want brand new...that's just me.

But if I had 4-416's...then zilch's comments are spot on not just because that is exactly
what I would do. But it makes me think I could design a 3 way system with the behringer
and maybe have some passive xo across one of the 416Bs to keep the other one focused to
the midrange horn....now you got me thinking!

[Altec Best]

[quote=Steve Mac;1829458]

I am in somewhat a similar boat that I am beginning to put another system together
not too different than yours. Except I like simpler projects...yours is a beautiful but
could be a real gorilla in tweaking...but no doubt it might be worth it.

This is what I'm finding out and your right Steve I think it's worth it.

I'm thinking 511E but with GPA288H drivers...the high end is better methinks
so I do not need the ev tweeters...though gm may add that the ev tweeters bandwidth

may be more appropriate.

I have a couple different pairs of 288's ,I want to use these because the diaghrams are Brand New

Still I truly believe the fewer number of transducers...the better.
I'm thinking of the alnico gpa 416 speakers...I want brand new...that's just me.

1 pair of 416's are used but in great condition and the other pair I have are NOS still in the Altec Boxes.If I need to recone them (Used Ones) I will.

But if I had 4-416's...then zilch's comments are spot on not just because that is exactly
what I would do. But it makes me think I could design a 3 way system with the behringer
and maybe have some passive xo across one of the 416Bs to keep the other one focused to
the midrange horn....now you got me thinking

But I truly believe that 1 woofer cannot keep up with a 288 without having to shelve it completely it just overpowers and drowns out 1 LF transducer.In almost every Altec system that a large format driver is used 2 woofers are usually the norm.Let me know if you come up with anything !!

I'll send GM a email see if he can help Thank You Steve ! :2thumbsup:

[SOOTSHE]

I'm afraid I'm not going to be much help John.....It's going to take all my wits to come up with the new crossovers for my 19's even though I have the schematic!!! I'm a complete novice at this crossover stuff.

Having said that, I'll be following this closely though, as I think you are putting together a killer system here. What type of design are you going for with the bass bin?

I think the dual 416's will be awesome....are you thinking 500hz, 6K?

[Steve Mac]

But I truly believe that 1 woofer cannot keep up with a 288 without having to shelve it completely it just overpowers and drowns out 1 LF transducer.In almost every Altec system that a large format driver is used 2 woofers are usually the norm.Let me know if you come up with anything !!

I'll send GM a email see if he can help Thank You Steve ! :2thumbsup:

passive yes...active no...the secret of my success have been the attenuators I use on the output of the behringer XO...that way I pump up the juice to the crossover but limit signal to the power amps. One big benefit of active is I can try hundreds of slopes/gains, eq,safety limiting, etc with the behringer... in effect I don't want the amp/speaker/xo to be tied together...it's just too limiting. I'm seriously considering an SET amp for the smaller system on top and with bi/tri-amping it's so much easier to mix/match and experiment.

I believe in your case you are trying to build the rod speaker right? If that's the case you need to research what they used for that project and tweak away.

[Altec Best]

What type of design are you going for with the bass bin?

I think the dual 416's will be awesome....are you thinking 500hz, 6K?

I'm not sure yet on the bass bins I'm waiting to see what GM says about an over and under drivers with a sled on top for the horns.As far as the 511 horn I would like to see that go to at least 8k or 10k and then bring in the T350 around there.

I believe in your case you are trying to build the rod speaker right? If that's the case you need to research what they used for that project and tweak away.

Similar to the Rod I prefer the drivers over and under GM built one like that if you check out his album on his profile page he has a picture of one with a 511 on top.I'm thinking something like that except with a T350 as a super tweeter too I talked to him yesterday but he is alittle under the weather right now Hope he gets well soon :2thumbsup: Thanks Steve :thankU: John

[bfish]

I'd suggest measuring the T/S parameters on your 416s before settling on boxes for them. Any two in one box need to be verrry close ITR. Impedance plots and matching that as well. AFAIK, the current kits are the one-size-fits-all 416C kit Altec was using when they quit, so if you recone any, you'll probably need to do them all for the best matchup, and even I would wince doing that to NOS Bs.

Another option to use what you have if they don't match well enough is a 4-box MTM.

Doing a passive XO for a 3-way with mid and HF horns of such vastly different dimensions... I wouldn't go there. Go active 3-way and dial in the XO and delay. Be aware though that not all active XOs offer delay for the HF.

[Altec Best]

I'd suggest measuring the T/S parameters on your 416s before settling on boxes for them. Any two in one box need to be verrry close ITR. Impedance plots and matching that as well. AFAIK, the current kits are the one-size-fits-all 416C kit Altec was making when they quit, so if you recone any, you'll probably need to do them all for the best matchup, and even I would wince doing that to NOS Bs.

Another option to use what you have if they don't match well enough is a 4-box MTM.

Doing a passive XO for a 3-way with mid and HF horns of such vastly different dimensions... I wouldn't go there. Go active 3-way and dial in the XO and delay. Be aware though that not all active XOs offer delay for the HF.

Thank You Brad for your suggestions Much Appreciated !!! :2thumbsup:

I've always used passives I know,I know, I got to get with the times Do you have a suggestion on make and model Active crossover as I don't have a whole lot of experiance on them and need your guys observations on such units and best way to proceed with this.

The last thing I want to do is recone those NOS they are just to pretty to do that too.Because if I did I would have to go and have my head examined. I've been saving them for a long time.And now is the time to break them out.Thanks again Brad for your Help !!! :thankU: John

[bfish]

You're welcome.

I've not used one, but this has all the bells and whistles;

BEHRINGER: DCX2496

Pretty popular among DIYers, just verify it'll do stereo 3-way.

The beauty is in the flexibility. Build a passive for that system and that's all it's good for. Considering how most of us are forever tweaking, I'd rather do it with software than a soldering gun and mail-order parts.

[GM]

I'd suggest measuring the T/S parameters on your 416s before settling on boxes for them.

AFAIK, the current kits are the one-size-fits-all 416C kit Altec was using when they quit........

Another option to use what you have if they don't match well enough is a 4-box MTM.

Doing a passive XO for a 3-way with mid and HF horns of such vastly different dimensions... I wouldn't go there.

Agreed, though not a big deal in most sealed apps. Vented is a different matter since even the dissimilar path-lengths between the drivers and vent accepts power sharing. In extreme cases, I've seen one woofer 'hog' most of the power, causing it to audibly distort due to both thermal power compression as well as over excursion while the other woofer is mostly acting as a passive radiator. For most HIFI/HT apps using large HE woofers though, it's normally not a concern.

Still, when the desired driver/vent layout allows it, putting each driver in its own vented 'cab' is a good plan if for no other reason than the divider makes for a much more rigid cab and each can be individually tuned/optimized.

Bummer, guess if I ever need one of my 515Bs re-coned I'll have to sell them.

4 box MTM?

Yeah, been there, done that way back when and why I swapped 805/288 for 511/802 to get a satisfactory HF response and later adding a second pair to get the larger horn combo's more robust mids to 'have my cake and eat it too'.

GM

[bfish]

...Bummer, guess if I ever need one of my 515Bs re-coned I'll have to sell them...GM

(OT response, but probably worthy anyway.)

(There may be 2 options for 515s, so you may not be out of luck).

This should be self-evident if one peruses the various driver/kit lists from the 70s thru GPA, but the concept doesn't seem to have widely sunk in, and IMO is at least in part the reason for some of the expressed dissatisfaction with GPA recones. Look at the wide array of kit numbers used in various versions of any given long-lived model on the '75 reference. Any change in software created a new part number. Some may have been from different vendors (Altec didn't make their own cone kits), others used newer materials and methods. The consolidation of all those historical versions into a single "what's available/best choice now" version was a decision that Altec made way back when (see the parts lists from the 80s & 90s). This seems to have been translated somehow as GPA's "fault", which it isn't. It's a practical decision that Altec made, and GPA is stuck with.

Would I like to have kits available (in made-yesterday condition) for all my various drivers? Of course I would, but I have to accept that it ain't any more likely to happen than me getting my 18yo body back. People move on and die, companys get bought and sold, and we make the best of what's dealt us. "Progess" may be subjective, but change is inevitable.