"Crossover Design for New Project"

[Panomaniac]

Wow! What a great offer. It' wonderful what you can do with a good table saw and a guy who knows how to use it.

[Altec Best]

But what do I do with my table saw and router table and all my tools.

I have a better idea how about I'll build them throw them in the back of my truck and drive up there for a listen oh yeah and I'll pick up a couple cases of beer,I like that idea better. Do you have a good amp !

[edharbur]

Sounds like a better plan.

My amp situation is pretty lame - but this could be the excuse that I've been waiting for....

Ed

[GM]

Now I talked to the Zilchster and he recommended that I use one of the woofers to 100 hz and below to augment the Bass as running both at full range they would conflict in the midrange.

There's some definite advantages to this when the XO point is > ~1 WL away from a dual driver's acoustic center and you're not far enough away from the speaker(s) to make it a moot point, so at a glance the way around this is to either use a vertical MTM or horizontally opposed layout depending on the app.

WRT mids confliction, I don't recall this ever being an issue with either the 500 or 800 Hz versions using horizontally opposed woofers plus it has the advantage of being able to control directivity to a lower frequency in the horizontal plane, so if the space permits, this is my preferred dual woofer layout.

GM

[GM]

I'm a big fan of active EQ...

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.

Me too, with the caveat that there's a certain synergy of matching a compression horn's impedance, so I prefer passive CD horn EQ when driven with a very low output impedance source.

When it comes to the highs, it's mostly about what sort of power (polar) response is required and how much EQ is required to contour a mids horn to do double duty as a super tweeter.

I felt the same way until I auditioned DSL's three way SH-46 awhile back.........

GM

[GM]

[quote=Altec Best;1829472]

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 !!

That, or horn load a single to produce the output of two with the trade-off being a truly huge cab if loaded enough to match the dual woofers down low.

The question though is whether or not the 288 has enough dynamic headroom left once shelved to meet the needs of the app. For prosound it doesn't, but for HIFI/HT apps it should except for maybe the 'Headbanger's Ball' types.

GM

[GM]

... 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.

Agreed, though I prefer lots of Class A or at least very low -fb SS power with passives to impedance match to compression horns to keep from clipping transients.

GM

[GM]

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 talked to him yesterday but he is alittle under the weather right now Hope he gets well soon

FWIW, I've periodically mentioned that my current speakers are anything but optimum. They are the original 'subs' used to fill in below chopped up 210s except with ~stock 511/808-8a loaded with Ultralights to effectively make them 802-8A. As such, they suck by my standards, sounding best from outside the room and even then, music scales obnoxiously 'walk' up-down between the horn/woofers and some musical instruments sound way too tall due to the acoustic centers being so far apart for a N501-8A.

WRT adding super tweeters, ideally you want to match the two horn's polar responses at least around the XO point, but I've never seen any published plots of older speaker components other than Altec's, so typically requires lots of trial n' error if no measurements are made.

Thanks, though for me, getting 'well' these days means not feeling as bad as the day before.

[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

[GM]

I don't think I'd go below 700Hz 2nd order on the 511/288.

Why? I mean a 288 on a shortened 511 is from an acoustical loading POV about the same as an 802 on a stock 511, so a 500 Hz XO is appropriate.

GM