Help asilker perfect his Altec 604's

asilker

asilker

Super Member
Hey folks

Love the pair I've got right now. In the interest of making them 100% perfect, I have ordered reproduction Mantaray logos, and I will be purchasing more roxul soon for room treatment. I have two questions. Hoping some Altec nuts can help me.

1. I'd like to touch up the silver paint on the front of the Mantaray horns. It looks like they're attached by 2 hex bolts near the throat. Are these easy to remove or should I beware?

2. My pair have great plains audio crossovers. Can I install an Lpad to take some shout? We're not homeowners so I'd like the option to tune them per room

Thanks folks
 
1. I'd like to touch up the silver paint on the front of the Mantaray horns. It looks like they're attached by 2 hex bolts near the throat. Are these easy to remove or should I beware?

DS: I'd not upset the force, Luke. Do not try to remove the horns. Look closely and you'll see they're part of the dust cap/spider system, most likely.

2. My pair have great plains audio crossovers. Can I install an Lpad to take some shout? We're not homeowners so I'd like the option to tune them per room.

DS: This implies they're a bit forward for your taste or room size. They need a lot of room space to get that balanced out with extra EQ'ing. I built a set of the Marquart xovers and liked them for smaller (aka: one car garage size) rooms. I'd contact Bill H at GPA for guidance on the mods to his xover.

Cheers,

David
 
You can install an 8ohm L pad between the crossover high output and the horn with no problem. The L pad will come with wiring directions. Very simple.

The Markwart crossover suggestion is your ultimate answer, though. It equalizes and time-aligns the horn/woofer and, by all accounts, really smooths out the frequency response.

http://home.earthlink.net/~jmarkwart/

GeeDeeEmm
 
Very cool, thanks for the input guys.

I will not remove the horns.

I'll be reading up about crossover options. Does anyone know of a page that compares crossover designs for the 604 driver? Seems like lots of folks have lots of opinions. As of now, I'm aware of stock, active, GPA,watering labs, and markwart. Any others I'm missing?
 
I don't have 604s, but I read all the 604 sites and posts, and it seems that, so far, the Markwart design is the best passive eq designed for those speakers.

Of course, you can always go active and dial in exactly the sound you want. If you don't want to build crossovers, that may be your best bet.

GeeDeeEmm
 
I've still got a set of the stock 604-8K crossovers redone with new caps. They're not as high performance as the Markwart. They tend to sound more 'shouty' in the mid-range whereas the Markwarts are much smoother.

No experience with the GPA or the Mastering Labs xovers. The challenge with the Mastering Labs is getting your hands on them, IME. I'd expect the GPA xovers to be pretty good, though.

Cheers,

David
 
FWIW I have - as many of you all probabl know, and at least for the time being - abandoned the treble horns of my 604Es (with Mastering Labs XOs) and moved on to horns that substantially widen the 3D "sweet spot" (at least as I have had my Duplexes configured).

DSC_7248 by Mark Hardy, on Flickr

This may not be what the OP's interested in even considering -- but after living with (and really, really enjoying) a pair of Duplexes for quite a few years, I started fiddling around.

DSC_7250 (2) by Mark Hardy, on Flickr

(I should really invest in a pair of 515 or 416 woofers...)
 
Looks like the JM crossover to do is the "Altec Lansing 604-8H Phase-Correct Crossover with MF EQ".

That's for 8ohm drivers, right?
 
They do some things magically well, and they are a truly versatile driver that can offer high resolution for critical monitoring as well as high level playback sessions in the same package. They are also fairly obsolete in those capacities by today's professional audio standards.

If you want them to be perfect, you need to increase the mouth area of the horn by a factor of 50 while maintaining proper flare rate, and not adding any amount of increased obstruction in front of the woofer cone. Of course, the laws of physics render this completely impossible. Welcome to the 604's Achilles heel. It's not perfect, and cannot be made that way.

I have owned many 604's, some from factory new, and lived with them nearly continuously since the mid 70's until just a couple years ago. My journey with 604's is well over at this point. In my audio world they do not justify their value/expense, they are strictly flip fodder for me these days.. It's quite possible using Altec components to build better sounding speaker systems for less mopney. Some folks like farming unicorns....................... different strokes.
 
I peeked inside my cabs and I have Great Plains Audio N604 8a crossovers.

Should the Markwart XOs be an improvement over these?
 
I have ordered parts for the Markwart XO's. Could anybody show me a photo of how you laid yours out?

I remember @Billfort mentioning in his room thread that he kept his external...
 
This is my layout before wiring and the addition of bypass caps. I did some research first about crossover layout, and found some other examples of Markwart xovers online.

I wired mine with 12awg wire, and used Russian bypass caps

These are just temporary boards until I figure out what I want to do with mine. I have some nicer Ash boards I will move mine to eventually. That is weathered white pine they are on currently.

Mine are kept on top of the 620 cabs. IMG_7890.JPG
 
elitopus said:
This is my layout before wiring and the addition of bypass caps. I did some research first about crossover layout, and found some other examples of Markwart xovers online.

I wired mine with 12awg wire, and used Russian bypass caps

These are just temporary boards until I figure out what I want to do with mine. I have some nicer Ash boards I will move mine to eventually. That is weathered white pine they are on currently.

Mine are kept on top of the 620 cabs. View attachment 980162
Click to expand...
Thanks, that's useful. What sort of capacitors are those?
 
I used Genteq motor run (oil) caps, Jantzen coils, and Dayton resistors.

I built these around Christmas last year, and they sound better all the time.
 
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