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Altec 604-8g

Nice set up with the 1st generation UREI horns installed plus the Mastering Lab xovers. Cabinets would need to be bigger to get the bass out of them. Hope they don't need reconing, though.

T@Rromeo: The difference between the Markwart and stock crossovers is apparent immediately. The sonic image snaps into place and, if you've got the electronics, the sonic image will appear out in front of the speakers but also will appear wider than the speakers are spaced. While I've never heard them, the Mastering Labs xovers will do the same thing as will the UREI 811/813 versions.

This is the result of the Markwart design moving the phasing of the horn tweeter to the acoustic point source to that of the woofer - time alignment. The Altec crossovers do not account for that.

The crossovers will have to be built as I have not seen them sold commercially. They aren't hard to build, actually, if you lay the parts out on a wood sheet and then wire them as shown in the schematic. Just remember to swap the leads on the horn driver so that it is time alignment.

Cheers,

David
 
dshoaf said:
, if you've got the electronics, the sonic image will appear out in front of the speakers but also will appear wider than the speakers are spaced.

This is the result of the Markwart design moving the phasing of the horn tweeter to the acoustic point source to that of the woofer - time alignment. The Altec crossovers do not account for that.


Cheers,

David
Click to expand...

"if you've got the electronics" - can you expand on that a little?

Art
 
Ok.
Been reading up on Jeff Markwart's crossovers.
So change of plans.
Markwort crossovers before larger cabinets.
Got the schematic.
Never built crossovers before.
Should be a fun adventure.

Art
 
Sean Custer said:
604's are incredible speakers they are the speakers responsible for getting me into horns. Here is a link that will give you valuable crossover information regarding the 604 series Altec's. Hope you enjoy your as much as i enjoyed mine. http://home.earthlink.net/~jmarkwart/id11.html
Click to expand...
Maybe read thru the threads a bit before you post eh?

You've posted Markwart's site in both of the OP's threads after it's already been posted and discussed multiple times. In fact the OP mentions how he has been studying Jeff's site in the very last post before yours above.
 
Has anyone tried Great Plains crossovers on thsee speakers? They come already built. I have no skills so it might be the way I go.
 
rromeo said:
Has anyone tried Great Plains crossovers on thsee speakers? They come already built. I have no skills so it might be the way I go.
Click to expand...

If you can figger out which end of a soldering iron to hold, and can watch a basic 60 second tutorial on forming a proper solder joint, you can build crossovers....
 
sempai said:
"if you've got the electronics" - can you expand on that a little? Art
Click to expand...

What I'm implying is that once you've got the speakers dialed in, you'll be able to hear the effects of the upstream audio components. Specifically, you'll be able to hear that some amplifiers do a better job of maintaining phase-correct signals between channels.

For instance, the McIntosh MC-225 actually specifies a < 10% phase difference between channels. If the speakers can process it, then you'll hear amps that don't do this.

Thus my comment, "if you've got the electronics". Probably should have used a better reference, eh?

Cheers,

David
 
dshoaf said:
What I'm implying is that once you've got the speakers dialed in, you'll be able to hear the effects of the upstream audio components. Specifically, you'll be able to hear that some amplifiers do a better job of maintaining phase-correct signals between channels.

For instance, the McIntosh MC-225 actually specifies a < 10% phase difference between channels. If the speakers can process it, then you'll hear amps that don't do this.
Click to expand...

Actually the O/M lists phase shift for MC225 as +/- 15 deg;+/- 6 deg - MC240; +/- 8 deg - MC275.

In any case, exactly how much would you consider audible/tolerable in your experience David? (Assuming used with a 604 H w/ Markwart crossover)

Also, is it possible for phase shift in speaker and amplifier to cancel each other out?
 
@62caddy, I have no idea. I cited the Mac specs because they're one of the few vendors who even bothered to provide a spec. I can't recall others who might have done so.

I'm attributing a lot of what I hear to the interaction of speaker group delay functions which then interact with the amp's ability to remain phase-stable. I can't measure it so am using only my ears to report out here. In other words, I'm jumping to a conclusion that I can be easily persuaded isn't correct.

For more on the topics from an objective point of view, here are some links in no specific order. Warning: these will take multiple beers to get through. Stock up!

Deep doo-doo on Group Delay here

Deep doo-doo on measuring it here.

Even more deep doo-doo here.

Dick Heyser (JPL) on Phase and Time Delay Distortion

Less deep discussions

Discussion of phase and time delay via Room EQ Wizard

Pro Sound Training on Phase and Group Delay measuring

Isn't this fun?

Cheers,

David
 
If you like books, John Eargle and Chris Foreman's JBL supported "Audio Engineering for Sound Reinforcement" is my go to reference for many things, and it still works during a mains failure. They pare most things down to where even a hack like myself can grasp them.

51UygQYxb1L._SX258_BO1,204,203,200_.jpg
 
Back to the OP, you might want to take a look at this crossover. It was a joint design specifically for the 604-8B by Dennis Had formerly of Cary Audio, and Michael Mardis/Panomaniac of the Altec forums, who was also involved with Hiraga.

 
604_6.jpg

I built this pair of loudspeakers using the Great Plains reissue of the Altec 604-8H II driver, and they are magnificent. The cabinets however are enormous at 10cu/ft of internal space.
 
Sean Custer said:
604's are incredible speakers they are the speakers responsible for getting me into horns. Here is a link that will give you valuable crossover information regarding the 604 series Altec's. Hope you enjoy your as much as i enjoyed mine. http://home.earthlink.net/~jmarkwart/id11.html
Click to expand...

Well, I appreciated the link, as I had somehow completely missed previous references to it. But, then, my entire life has been marked by repeatedly ignoring the obvious! :)

GeeDeeEmm
 
analog addict said:
Back to the OP, you might want to take a look at this crossover. It was a joint design specifically for the 604-8B by Dennis Had formerly of Cary Audio, and Michael Mardis/Panomaniac of the Altec forums, who was also involved with Hiraga.

Click to expand...

This might very well be a good design.
But I wouldn't be able tell.
Maybe you could describe (in layman's terms) what's happening here and what one is likely to hear.

In the meantime I am moving forward with purchasing bits for the Markwort crossovers.
Last week The postman dropped off a big heavy package full of Russian PIO caps.
Now I'm looking for a quality potentiometer and am open to suggestions.
And still need to pick up some resistors.
Then we'll be ready to go.

I'm considering winding my own air coil resistors but I'm not sure I want to spoil this project with potentially inept execution.


Art

edit: skipped right past the graph you posted. doh! Never mind. Thanks for the posts.
 
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The adventure continues.
Just ordered some Belden 9497 cable.
Wondering if anyone has tried this cable and if it is deserving of its reputation.

Art
 
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