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Ideal cabinet for Altec 604D's?

J

judgeschreber

Well-Known Member
Ok, so I got ahold of a second 604D for a very reasonable price, and now I'm ready to start planning a speaker system. I will definitely build new time-aligned crossovers ala Jeff Markwart. But, now I need to figure out what kind of cabinets to build. Any ideas?

I've heard that 620's are the way to go, but I've also heard that they were more ideal for 604-8G, and that a higher cabinet tuning and/or smaller cabinet volume might be better for the 604D's. Anyone have any experience with these?

I believe they are basically identical to the 604C's, and similar to the E's, except that the E version has an accordion-style doped cloth suspension.

If I can get a decent price on the E version cones, I may recone these, since the E version is supposed to have better bass response.
 
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Billfort has some beautiful Altec 604 speakers. I don't remember what specific model it was but you might want to do some searches and or contact him. BTW, I like the Altec dual concentrics. Those are drivers worth building some nice cabs for.
 
Go to the unofficial Altec forum and ask a fella named GM. He knows more about Altec cabinet tuning than anyone I've run into.
 
GM= Greg Monfort, unless I'm mistaken.

If so, I know him... and yes, he's quite a repository of Altec cabinet specs!!

Regards,
Gordon.
 
Judge, just curious if you checked out Selmerdave's 20 cuft MLTL tuned to 27hz?

The thread is titled "New Cabinets" and can be found about halfway down the first index page.

Greg (GM) gave very detailed instructions on how to build the "pipe" in a thread a few months ago, newer 604's with the accordian surround will play down to ~16hz in this box, i'm not sure if the older paper surround models are appropriate for this. One definite advantage tho is that the driver gets mounted at ear level without stands or legs which is important with 604's.

Let me know if you need help finding this thread as the archives on that site can be a challenge to search thru.
 
GM is quite the cabinet whiz; I didn't know he was an Altec expert. My dealings with him have been mostly in the context of the Full Range Forum (www.fullrangedriver.com )

FWIW, my (long-term) plan is to replicate Billfort's cabinets for my 604B's. It's not a plan that is moving any to swiftly. I would have my woodworker/contractor friend Mike Berg (who made my TQWT's) do them.
 
Thanks for the references, guys. Yes, the hostboard seems a bit tricky to navigate for me, but I did find a lot of info. It looks like the stonehenge V or the altec 620 is ideal, and people seem to think it will work well with the C/D version. I do want to check out Selmerdave's cabinet--is that the same as the "pipe," or are those two different cabinets?

While I'm waiting to draw up plans and construct new boxes (which, considering the amount of spare time I have, may be a long time), I think I will put the drivers in some GE cabinets I have that are about 4.5-5 sq feet. I know it's not ideal, but I found some info on hostboard that suggests these can be made to work pretty well, and suggests tuning cabinets of this size to 40hz. I will have to make a new baffle and vent, but I hoping it won't be too much work--more just a matter of getting the measurements right, I think.

Should I go with the recommended tuning frequency (it was cited on the hostboard as coming from an official Altec technical letter), or should I measure the T/S and try to make it more ideal? I would need help with that second course of action, but there seems a bunch of people willing to help on this forum, so I may give that a shot.
 
Here's what I did for Altec 604-8G's.

604finished.jpg


These are 9cu.ft. vented boxes, 40Hz vent tuning, cherry veneer over Baltic birch with a bunch of internal bracing and a pretty labor intensive fully mortised type construction. They are loosely based on the 620 cabinet where I tried to keep what I considered important about that design (volume, tuning, baffle width) but got the driver center up to ear level and attempted a cabinet with a more modern appearance and better positioning flexibility. They originally went in a small (11' x 12') room and the option of corner placement was important to me.

Much has changed since I built these and the above picture was taken - most of my system has evolved, I'm using a Markwart crossover and they are now in a bigger (12'6" x 22') dedicated listening room - but I have grown to love these speakers and don't see myself ever parting with them.

I haven't heard 604D's but have heard E's and G's in various vented boxes, 620A copies and different constructions using everything from 3/4 Baltic birch or MDF all the way up to 1 1/2" think MDF. My preference is BB 3/4", well braced and using the 620 tuning and baffle width. Even though the TS specs I could dig up for the E's seem to indicate you get the flattest response out of a smaller box than the 620, extensive listening to a friends E's (Mastering Labs crossovers) made it pretty clear to me that a BB copy of 620 was the best sounding.

I haven't tried much larger cabinets or any flavor of 'pipe' as domestic limitations always meant they had to fit in the room and look OK but even now that I don't really have those concerns, I'm happy enough with them to leave well-enough alone.

I put a webpage up sometime ago that described my early experience with these and shows how I built them.

http://www.wardsweb.org/Billfort/
 
Even though the TS specs I could dig up for the E's seem to indicate you get the flattest response out of a smaller box than the 620
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Yes, for 620 or larger boxes with lower tuning, some EQ is required.

Judge, i'll search the archives as time permits for the 20 ft pipe thread. GM originally presented it as a subwoofer enclosure for 416 woofers. Ultimately others chimed in about the possibility of using 604's in the same cabinet, hence Selmerdave's project.

This is a seperate thread that spawned from the original which i have yet to locate:

http://www.hostboard.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=3729&t=2636

Also keep in mind that you'll need to build your cabinets with a removable mounting baffle or otherwice facilitate access to rear mount your D's.

Any route you choose will be a worthwhile and rewarding venture.
 
bowtie427ss said:
Yes, for 620 or larger boxes with lower tuning, some EQ is required.
Click to expand...
No EQ other than what the Mastering Labs crossover does was used on the ones I heard. I would say this is a matter of personal preference (and maybe system dependent?) as the E's sounded great to me in the 620 cabinet.
 
I should have been more specific in regard to the driver, pretty sure that the damping and surround of the E and 8G give them a lower resonant frequency than the C and D versions.

I agree, my 8G's(model 17's) sounded spectacular with just the stock networks in the 620 box.

Won't putting the C and D versions in a larger/lower tuned boxes cause anomalies in the upper range of the woofers response without some EQ to smooth it?.
 
I just tested my 604D, and the resonant frequency was pretty high, at 50hz. The E is supposed to have an Fs of 25hz, which seems like quite a big difference to me.

So perhaps the smaller enclosure I'm planning is a little bit better for the D version, and I'll just have to live with less bass response.

If the Fs is 50hz, shouldn't I aim a little higher than 40hz for the cabinet tuning? Maybe something around 50-55?

The other option is to recone with E cones, which can be had for a decent price on the bay. The different surround is supposed give a lower resonance.
 
Yes bowtie, my comments are strictly based on experience with the E in a 620 box which on paper seemed better suited to the G - I have no idea how this would translate to the earlier versions that I imagine have quite different TS specs.

Has anybody measured a D or seen the TS specs for it?
 
Great information here. I'm just reading this as I comtemplate what to do with my 604B's should I decide to keep them. I need to make them work within a 5 cf gross cabinet if that's possible.
 
Here's what I just tested on my 604-D:
DCR= 9.0
fS= 49.684
QMS= 5.878
QES= 0.219
QTS= 0.212
RES= 250.083
LE= 0.300
n = 0.517

If anyone can let me know how to calculate the other parameters from these, that info would be helpful. The Vas looks a little more difficult to calculate, for me at least.

Also, if anyone can give some insight into what these numbers mean in terms of building cabs, I'd love to hear it.
 
I need to make them work within a 5 cf gross cabinet if that's possible.
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So long as your not looking for much below 40-45hz, 5 cuft is almost the "universal" volume for many 15 inch woofers.

It seems that several of the smaller Altec boxes for their 15 inch duplexes were tuned around 60hz.

I think the 620 tunes at 35hz and might be asking a bit much of a paper surround driver with fs of 49hz.
 
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