[TerryO]

So if I don't want to deal w/ a sub, "boxes" may be the way to go?

That's a option that is certainly open to you. I was under the impression that you wanted to use the 604's with a JE Labs open baffle. There are other options, some have been mentioned here and perhaps the one you may want to consider is a taller, narrower baffle (20-24 inches) with the Eminence 15" alpha woofer. It has a Qts of 1.25 which is quite good for OB, as it curtails or eliminates the need for EQ. I believe that over on diyAudio.com there's been a number of threads on this sort of situation. Look for posts by Martin King, among others.
Another possibility is to use a Karlson enclosure having the OB with the 604's on top of it. Cross it over at 50-80 Hz (to your taste) and you'd have one real Major Mojo Machine with real dynamics and considerable slam.
The key to diy is "tiy" (try it yourself), but there are a lot of other people's experiences, that can give you a fair idea as to what to expect on your project. Hang in there!

Best Regards,
TerryO

[gortnipper]

So if I don't want to deal w/ a sub, "boxes" may be the way to go?

I am going to do a JE labs OB as a trial run for the near term when I receive my impending purchase of GPA 604s. Then, as woodworking time allows I am thinking I will do a MLTL a la Stephaen's - http://www.6moons.com/audioreviews/altec/dream.html. Have to finish a couple other "small" jobs first though...

David

[chrismercurio]

I already bought the subs and will know how well it all works in a couple of months....

What are you going to have for subs? Are you building your own enclosures or is it a package deal?

Best Regards,
TerryO

I bought a pair of Maelstrom X's and will power them with Velodyne SC1250's. I am building sealed boxes.

Chris

[stlblue]

So if I don't want to deal w/ a sub, "boxes" may be the way to go?

I am going to do a JE labs OB as a trial run for the near term when I receive my impending purchase of GPA 604s. Then, as woodworking time allows I am thinking I will do a MLTL a la Stephaen's - http://www.6moons.com/audioreviews/altec/dream.html. Have to finish a couple other "small" jobs first though...

David

I've been thinking of do the exact same process. I'm guessing you'll finish both before I do. 

[stlblue]

So if I don't want to deal w/ a sub, "boxes" may be the way to go?

That's a option that is certainly open to you. I was under the impression that you wanted to use the 604's with a JE Labs open baffle. There are other options, some have been mentioned here and perhaps the one you may want to consider is a taller, narrower baffle (20-24 inches) with the Eminence 15" alpha woofer. It has a Qts of 1.25 which is quite good for OB, as it curtains or eliminates the need for EQ. I believe that over on diyAudio.com there's been a number of threads on this sort of situation. Look for posts by Martin King, among others.
Another possibility is to use a Karlson enclosure having the OB with the 604's on top of it. Cross it over at 50-80 Hz (to your taste) and you'd have one real Major Mojo Machine with real dynamics and considerable slam.
The key to diy is "tiy" (try it yourself), but there are a lot of other people's experiences, that can give you a fair idea as to what to expect on your project. Hang in there!

Best Regards,
TerryO

I'd like to do a JE Labs OB, but I'm not interested in doing a sub. As you said, I'll try it and see what happens. Thanks for sharing...

[chrismercurio]

The nicest thing about OB's, especially that style, is that you can be up and running the day the drivers arrive.

Chris

[gortnipper]

 

[panomaniac]

You don't have to use boxes ("we don't need no stinking boxes").  Just don't want you to be disappointed in the bass output.  There won't be much with the 604 on OB.  What there is will be super clean, but it won't be a lot.   And it may be just be me, but if I'm putting a pair of 33x35" baffles in my room, I don't want to have to use a sub.

So you have a couple of choices.

1) Do some clever x-over and/or EQ work to get the bass you want out of the 604s on your baffle.
or
2) Add a cheap  "bass helper" driver on the baffle.  That's what I'd do, and it should sound killer.

BTW, there are some very nice passive crossover designs for the 604 these days.

[chrismercurio]

That is what the subs are for. I know the Qt isn't high enough for lots of bass.

Edit:

From GPA:

Our new model 604-8H Series III (with the new horn and new crossover) is available as of this week, July 14, 2008, and priced at U$D 950.00 each (plus the applicable shipping charges).

[nullspace]

Hi Chris --

Any info you can share on the new horn? Details are few and far between, even at the Altec User's board.

Regards,
John

[chrismercurio]

I know it is similar to the UREI horn with output out to 22khz, but is not the same. I think they are building it in house. The new xover is said to be VERY flat with a minimum of components.

Chris

[panomaniac]

Ditto what Chris says. 
It's a biradial horn built in house, AFAIK.  Similar to the UREI.  Should go right on up and be clean.

[nullspace]

Thanks Fellas.

Michael -- Any chance we'll be seeing the new driver on OB from a friend of yours at RMAF? From the coverage, John's setup at LSAF looked very interesting and I for one am looking forward to seeing what he comes up with for Denver.

Regards,
John

[chrismercurio]

I just hope it isn't bright blue like the old UREI horn. I'm sure it isn't, but I didn't ask. I'm sure pictures and a new data sheet will follow soon.

Chris

[panomaniac]

LOL!  The crazy blue horn -with foam!  AFAIK, the new one is not blue (for better or for worse).
Jean Hiraga has his own custom made horn that will be in his new speakers based on the GPA driver.
http://www.jean-hiraga.com/uk/produits.htm

Any chance we'll be seeing the new driver on OB from a friend of yours at RMAF?

Unfortunately, no. At least I don't think so.  John and I were trying to put together a commercial version of the same rig, but it hasn't worked out,  However, John is currently working on a monster rig that uses a P.Audio 18" coax with 2 high Qts 18s underneath for low end support.
Yes. 3x18!!   John really likes the big P.Audio coax.  That is the rig that will probably be at RMAF.

[nullspace]

John is currently working on a monster rig that uses a P.Audio 18" coax with 2 high Qts 18s underneath for low end support.
Yes. 3x18!!   John really likes the big P.Audio coax.  That is the rig that will probably be at RMAF.

Holy mackerel. I can't wait to see that.

Any idea what room you all are going to be in? I don't know what name John goes under commercially.

Regards,
John

[gortnipper]

I took the plunge and ordered the GPA 604-8H-III today. The bad news is I wont be able to pick them up until second week in August when I get back to the states on a business trip to CA. But I will have OBs for them sorted by then ready for hook up on touchdown back home though....

[panomaniac]

I don't think John will be "official."  Just showing in his own room.  Bu maybe we'll bet his stuff setup in the AudioMagus room, you never know.

Watch this forum for news.

I took the plunge and ordered the GPA 604-8H-III today.

Hurray!   Congratulations.  You're going to be a happy guy.   What do you have in mind for a crossover?

[chrismercurio]

It comes with a crossover.

[panomaniac]

Is that crossover included in that price?  Cool...

For reference, Jeff Marwart has done very good crossovers for most of the Altec Coax drivers.
http://home.earthlink.net/~jmarkwart/index.html