Model 19 xover questions?

[Carl Bill]

I am finally getting back to planning stages of Altec projects! I have spent teh last 2 years building a new house and almost have the old hosue sold! Woo Hoo!

I am just now brainstorming (or brainfurting!) what I should try for a home theater system based on my Altec inventory.

I have a pair of never used Model 19 crossovers. I was wondering if I built some cabinets for a dual 416-8C setup, what would the crossover do with a 4 ohm load on the low end? I would like to try a Model 19-ish dual woffer build, but do not want to use active crossover if possible.

I will probably be back here a lot over the coming months while I get back to audio research.

I am also considering an Outlaw 990 processor/preanp to replace my aging Yamaha C-70 preamp. That should also cover the surround sound issue.

So much to figure out and still a lot left to do outside before winter.... landscape, fencing, dog containment, etc... no fishing this year

[bfish]

Originally posted by Carl Bill:
... no fishing this year

<font size="2" face="Verdana, Helvetica, sans-serif">That's what that gettin' hitched business will get you...

Good to hear from you CB! Just wanted to say Hi, but I'm not the one to answer HT Qs. I'm only here for the food.

[Carl Bill]

Yeah, that getting married part has caused quite the lifestyle change!

I figured the crossover question has been raised before and is probably a bad idea, but I wanted to start with that question before I started looking into more costly persuits.

I would think that reconeing the 416's to 16 ohms would make this much easier, but I think (?) all of the cones and coils are good at this time and hate to do that if not required.

Next and obvious questions would be box dimentions and port size(s). I think Altec built such a box for LF at some point and would use that as a start... but can't remember if they used 416's. That will be next week's search...

Right now I have to get some wiring done at the old house to get it sold and then build a bar for a hookah bar my step son is opening in OKC the first of August.

Oh the projects that I "get" to do.... :|

[selmerdave]

I will certainly defer to the more knowledgeable, but the short answer on the crossover is that it wouldn't work. As is because the change in impedance will cause the frequency of the crossover point to change for the LF drivers, and if you recone to 16-ohms they'll be 3-db more efficient than they should be.

I'd build a set of 19's and have a pair of woofers left over to build some dedicated subs, or forget the 19 crossovers and build some dual-15 cabinets with a DIY crossover.

Again, I'll defer to the knowledgeable on the suggestions.

Dave

[Carl Bill]

Yeah, I know that it probably wouldn't work. I was just looking for an easy way out.

I am not quite understanding why changing to 16 ohm wouldn't work, but please enlighten me. Could that situation be resolved with attenuation?

I love the Model 19's and would like to try and do a dual 416 variant. I assume it has already been done.

I was also considering an 18" sub on each side too... I am just in the brainstorming phase mind you... I will come down to reality when I have to start the build. I have a lot of "stuff" to do before build season....

I do appreciate the input and advice. I have a lot of knowledge and ability, but I am not at all an expert at this stuff.

Thank you for contributing!

[selmerdave]

Carl,

Yes you could attenuate a pair of 15's but then the purpose of doing that is seriously questionable given it's simpler, cheaper and quite likely easier to do it with a single 15.

I'd say if your heart is set on a pair of 15's per side, just forget about the 19 crossovers and build something designed around the pair of 15's. Likely wouldn't sound too bad There must be some people looking for 19 crossovers to give you some money for them...

Dave

[Carl Bill]

Yes, I am set on dual 15's to expand upon the 19's low end capability. I will also be looking at an 18" sub, per side, to help on the very low end.

I know this is extreem, but hey, I will die some day! I have the parts and the time coming up soon to do this, so I might as well aim high.

It will all come down to what will work/fit in the new house. I am still planning on putting together a fun 828 VOTT setup in the barn soon for fun to see what it will do. I hope I can figure out how to post pictures here. I also have a lot of vintage Altec employee party pictures from 1980...

[bfish]

Now there's one for the books...vintage Altec employees...lessee some eBay seller top that.

[Carl Bill]

I think I can keep the pictures focused on the employee provided speakers....


We had some partys!


North of OKC. I remember the Sheriff telling us that the neighboring farmer said his cows would not give milk due to the loud music...

I remember seeimg a bunch of steers in the fields the next moring! No milk farms near here!

[RonSSS]

The LF section of the model 19 crossover is dirt simple. 12db/oct. A series inductor and a parallel cap . Cap goes across the woofer.
My guess is you halve the inductor valye and double the cap value. But go find a simple crossover calculator to be sure.
Stock coil is 1.7mH, and the stock cap is 16uf.

Here is the schematic.



It will be 3dB more efficient....but to my ears, the 19 x-over could use more mid and hf attenuation anyway.

Cabinet volume for 2 416's is simply double that of one. Huge box! It won't go any lower, but will slam pretty well, especially if you EQ a bit.

Have fun!

I too have enough Altec stuff to do a home theatre. Even have the room. Would be a winter only deal, all tube based....but I bet it could be awesome!

Ron