View Full Version : Anyone else own Altec 604's?

11-06-2006, 08:04 PM
I just purchased a set of Altec 604's in an Onken style cabinet. These speakers sound so differnt than any others I have heard. My reference speaker would be the Altec Model 19. Just wondering if anyone else has listened to these and what was your 1st impression when you did.

I am running these without a crossover just a 6.2 cap from the woofer to the horn.

Hopefully your replies will macth my findings.

scott fitlin
11-06-2006, 08:54 PM
Ive never owned any 604,s but have heard them in studios many times.

To me, they have some of the best imaging, and coherent sound.

11-06-2006, 11:04 PM
.....snip......I am running these without a crossover just a 6.2 cap from the woofer to the horn.

Hopefully your replies will macth my findings.

If your findings tell you they sound like crap, you'd be right. Get some (correct) crossovers on them! I can think of few systems more critical of the right XO than a duplex. As it is, if they're 8 ohm, the cone's running fullrange, and is very capable of going way higher than the WL size of the horn in front of it, which simultaneously is going to be unloading from the 6dB slope from ~ 3200Hz. Polars will look like daisy petals. If they're 16 ohms, you've probably lost a 'fram by now.

604s are stretching on both ends to properly meet in the middle as it is, but with the right XO, cabinets, and location can be hard to beat. Don't expect quite as much bass as 19s provide (read-flatter response), and you should be very pleased when you get them setup right. I hear GPA now sells new XOs for all versions of 604s.

11-07-2006, 12:58 PM
I know others that have run 604's this way and multiple peolpe said that this would be fine to start with. I have not had any functioning problems. I am driving them with tube amps and a 5ar4 recitfier tube that is slow comming on.

Fram what do you mean by that? Also these are 160hms

11-07-2006, 02:53 PM
Perhaps you misunderstood someone's description of 604s in a biamped setup, where only a capacitor is used on the HF driver for thump protection. However, in such a system, a crossover is still used, but is a different type that's connected before two separate power amps, one for the cone, and one for the HF driver.

The tiny horn in a 604 has a sharp low cutoff around 1500Hz which varies slightly between models that used different horns. Below this, the horn no longer presents a load to the diaphragm (fram), allowing over-excursion which can ruin it. Stock XOs are 2nd order Butterworths with an XO point designed specifically for the horn in that particular model, so a 604A will be somewhat different from a 604E, G, etc. You need 16 ohm XOs, 8 ohm won't work.

There's way more to it than I have patience to describe. I'm not trying to diss either you or your speakers, merely emphasise the importance of the crossover, and perhaps save you a $120 'fram or two. Trust me, your 604s will perform nowhere near as designed (not even close) until you have appropriate crossovers connected correctly, or the equivalent in a biamp setup.

11-07-2006, 04:43 PM
I know the difference betwwen active and passive. This is the simplest crossover 1st order.

Since there are som many differnt crossovers for this speaker which one is best?

11-07-2006, 05:11 PM
That would be a 604-8K with modern revisions by Great Plains!


scott fitlin
11-07-2006, 05:26 PM
That would be a 604-8K with modern revisions by Great Plains!

RonIll second this. You get factory fresh crossovers, nice, new caps.

Well made, and built for your speakers!

11-07-2006, 06:15 PM
C'mon guys, you're slipping! He's got 16 ohm 604s!;)

Actually, a single cap is merely a high-pass filter. Without a corresponding low-pass filter included, it can't really be called a crossover.

As to which XO to select, ideally it should be the one designed for whatever model you have, for example, if your drivers are 604-16Es, a 604-16E XO would be ideal. Unfortuneately, used ones are pretty pricey lately. Ron's suggestion of new ones from GPA would be my choice as well, (only you need 16 ohm models instead of the 8 ohm ones he mentioned). If you go this route, just tell Bill your exact speaker model # when ordering. I don't know the price, but they're likely cheaper than some used ones go for on eBay, and no question as to the quality.

Your 604s being 16 ohm limits other more generic commercial choices, none of the online stores I checked had any that would work, lots of 8s, no 16s. DIY appears to be the only really cheap alternative.

scott fitlin
11-07-2006, 06:48 PM
Yes, tell Bill at GPA the model number, they will make the XO suitable for the impedance of your drivers!

This is important.

And, with proper XO, youll get the best your 604,s have to offer, no doubt.

11-07-2006, 08:35 PM
Are there any plans that I could follow to build my own crossovers?

11-07-2006, 08:55 PM
I don't have the website right now...check a search on audio.asylum for Jeff Markart(sp???) on the high efficiency section to find links to the Altec forum.

He has several according to the different model 604's!

Hope this helps!


11-08-2006, 10:13 AM
Thank You.

Just one more question would a pair of Altec 605B crossovers work 16ohms crossed at 16,000 hz?

11-08-2006, 10:34 AM
604 = 515/802
605 = 416/806

Roughly 2db difference between the two.

11-08-2006, 11:03 AM
From your post on Hostboard, I learned your 604s are either Cs or Ds, which crossed at 1600 (not 16000) Hz, and used the Altec N1600 16 ohm crossover. The N1600 is also the XO listed for the 605A and the 16 ohm 605B, so IF the crossover in question is a 16 ohm Altec N1600, the answer would be yes.

scott fitlin
11-08-2006, 11:49 AM
Are there any plans that I could follow to build my own crossovers?http://www.hostboard.com/cgi-bin/ultimatebb.cgi/ubb/forum/f/3729

11-08-2006, 12:27 PM
From your post on Hostboard, I learned your 604s are either Cs or Ds, which crossed at 1600 (not 16000) Hz, and used the Altec N1600 16 ohm crossover. The N1600 is also the XO listed for the 605A and the 16 ohm 605B, so IF the crossover in question is a 16 ohm Altec N1600, the answer would be yes.

There is a pair of 605B crossovers on ebay now that is why I ask. One of the drivers is a C and one is a D.

11-08-2006, 12:31 PM
here is the link:

http://cgi.ebay.com/PR-NIB-16-Ohm-Altec-Crossovers-for-605B-Speakers_W0QQitemZ160046240082QQihZ006QQcategoryZ5 0597QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

11-08-2006, 12:52 PM
That's an XO model I've never seen before, but it definitely is the correct XO for your duplexes, and obviously is in great shape.

If it were me, I'd price new ones from GPA, and let that be a guideline for bidding the eBay ones.

Good luck in your search!

Earl K
11-08-2006, 12:53 PM
- CLICK HERE ! (http://home.earthlink.net/~jmarkwart/index.html) to browse Jeff Markwarts' webpage.

- He has posted many schematics for his different crossover designs. He's covered off most of the various 604 & 605 duplexes .

- I believe I would first buildup the 604B ( with MF EQ ) for a listen .


11-08-2006, 01:09 PM
Yes I have read that page before and have it saved. I wrote him also on what he would think is the best way to go.


11-08-2006, 06:22 PM
Second Order (-12db per octave) Networks Two Way Networks
Impedance 16 Ohms C1 = 4.39uF L1= 2.25mH

Impedance 16 Ohms L2 = 2.25mH C2 = 4.39uF Frequency Hertz 1600 XO

C1 4.39
L1 2.25
L2 2.25
C2 4.39


11-08-2006, 09:51 PM
This seems pretty simple I should be able to build this I would think?

11-08-2006, 10:09 PM
That's as simple as it gets for generic, bare bones, though adding some form of HF attenuation will likely be desireable. Jeff's stock and enhanced Altec schematics are more complex with more components to optimize the performance of your particular speaker, and the difference will be audible. The simple circuit should suffice if you can't afford the other options at the moment.

11-09-2006, 06:40 AM
I owned a system with a 604-E and and 515B as a woofer.
The sound was very good. But I did not like the midrange. I found it to harsh. I always wonder if this was due to the cone not be able to crossover @1500Hz or to the horn being too short.

11-09-2006, 08:48 AM
I see that you were running it in a 3 way type.

I presume the low pass was 350 HZ Then 350hz to 1500hz on the 604E woofer
and 1500hz and beyond on the tweeter horn driver.

It's important to open the L pad all the way to let those High frequencies
out . Theres a lot of information above 3000 Hz .For example Vocals become clear at 3000hz and outstanding at 8000 Hz.

I could go on and on with evry musical instrument .We're getting into the field of EQ recording. Which is more complex than just putting a mic in front of an instrument.

HORNS AND STRINGS ....................SCRATCHY AT 3KHZ........................ ................................................. HOT 8-12KHZ...............................
................................................. HUNKY AT1KHZ.............................
................................................. CLARITY ABOVE 2KHZ....................
............ MUDDY BELOW 120HZ STRINGS ARE LUSH AT 400-600HZ.

HHHORNSornHorns and StringsScratchy at 3 KHz. Ho444400-600HZnky at 1 KHz. Muddy below 120 HzHORNot at 8-12 KHz. Clarity above 2 KHz. Strings are lush
I hope this has clarified how a sound system behaves.

.................................................. ...................;)

11-10-2006, 02:46 AM
:) The system was more like the famous JBL 4435 or the new model DD66000 with the 604 has a full range and the 515 as a subwoofer only.
The 515 was crossover with a huge coil inductance, around 120hz.
I beleive the cabinet was made back in the 1960.


11-10-2006, 02:59 AM
Here is the special Altec speaker

11-10-2006, 07:57 AM
I take it that they did not intially live up to your expectations? I echo the caveats about crossovers. I use mine with a variety of active crossovers, using tubes for the hi and ss for the low. I like the flexibility (ie. crossover point, time delay, independent volume control) afforded by active x's and the sound is very good. I have experimented with an actively crossed 4 way system using the 604's for the upper bass and mid with a pair of 18 subwoofers and some JBL slot radiators on top (xover points at 40, 1200, and 11k) and for home theater applications these guys will carry the mail. The other point that I would bring up, especially if bass extension is your concern is that many of the 604's I've listened too and seen have what I regard insufficient cabinet size to really let the 15" cones stretch out and fly. Mine are custom built 8.3 cu. ft. and left to their own devices can get down into the mid to low 30's very creditably. Putting these speaks in some of the 3.5 cu.ft. boxes I've seen is akin to castration, sonically speaking. That's what I think. Thanks

11-10-2006, 11:15 AM
Verry Nice Speakers indeed. This similar configuration was developed by Altec Lansing for the Japanese Recording Studio's in early 80's. The cabinets were 9.8 cubic feet. Dimensions ( H 44.68" W 24.8" D 18.5" ) . The model was a 4 way with an Altec Super Tweeter " discontinued ". The Xo were 350,1500,8000 hz. Passive XO.

Main components 604 8H , 416 and super tweeter.

11-11-2006, 08:59 PM
I'll do this.One day......
My 604Cs are gathering dust,the ideal was that a speaker could be made where 604C and 416 were combined in one box.
It can and it will get done.They will be used in conjunction with an active crossover.
I've DIY activated my Altec Valencia 846As,and they are merciless reflectors of the state of system health.Get the system sorted and they are "Event Recreators".

11-12-2006, 11:31 AM
I wrote Jeff Markwart on this subject and here is his response on the xo I should use:

The 604B Phase Correct Crossover with MF EQ ought to correct for the
phase shift between the ALNICO sections that the B through E models

The only question I had left was I thought these were supposed to crossover at 1600 as opposed to 1500 in his design.

11-12-2006, 11:13 PM
As I understand it, the slight variations in Duplex XO points were to best suit the horn model, there were at least a couple versions of the multicells, then the Mantaray. Wavelength at 1500Hz is 9.04", and at 1600Hz is 8.475", so a little over a half inch difference between the two.

If one were to assume a commercial design to include a little 'fudge factor' for safety sake, while an optimized design like Jeff's intends best performance, the change makes sense.

With the normal tendency of film caps to increase in value (uf, not $) over time, it's possible that any old Altec XOs with original parts you'd get could have drifted that much or more anyway. (While component drift is commonly encountered in old gear, my personal experience has been that the parts Altec used were exceptionally stable, and largely still in tolerance).

Short version; I ain't gonna make that decision for you, man.:no:

About the only issue you haven't mentioned yet is the diaphragms. If you haven't done it yet, I'd suggest checking them out, both electrically and visually (check the part numbers, look for damage). It'd be a bummer to get the XOs hooked up only to find more problems.