I am considering building cabinets for three 604C/D refurbed Altecs I have, and wanted to hear folks thoughts on sealed boxes. I recall that GM has suggested that they might work very well (with woofer/subwoofer support), but I believe his comments were in passing and not elaborated. My application her is a music oriented multichannel/HT room. I know they would be great in big MLTLs, but the smaller cabs will be easier to situate and offer more potential If I need to use them in smaller domestic rooms.
It looks like it might be difficult to go much below 2.5-3.0 cubic feet, so that's the size I'm looking at now. I've been using 605Bs in open baffles with 18" drivers in open back boxes below them for 10 years now, so I'm very comfortable with the duplexes and their crossovers.
This in advance,
Skip
It looks like it might be difficult to go much below 2.5-3.0 cubic feet, so that's the size I'm looking at now. I've been using 605Bs in open baffles with 18" drivers in open back boxes below them for 10 years now, so I'm very comfortable with the duplexes and their crossovers.
This in advance,
Skip
For what it's worth, I tried in a 8cu ft cabinet, didnt like the bass compared to the ported (MLTL) cabinets they came in.
Keep to MLTL for the L & R channels.
Keep to MLTL for the L & R channels.
I had 604s in big ported boxes. Maybe 10-15 cubic feet, I don't recall exactly. Worked great and there wasn't much change when I sealed the ports.
That probably doesn't help you much, but it's a data point. 🙂
That probably doesn't help you much, but it's a data point. 🙂
I had some 4cu ft boxes I used to stuff the ports on. I found that when sealed I could get them to integrate more smoothly with subs.
Hi John,
I'm looking forward to your new project. If you hadn't started me down the 605 OB path, I imagine I'd have built several Manzanitas by now.
In comments from Jeff Markwart's postings and GPA comments, I've gotten the impression that the 604 cone assemblies that GPS sells and uses in refurbs for older 604s match the 604E specs. The following are the 604E parameters from the linked listing for a bunch of Altec drivers.
Xmax 0.15"
Re 7.0 ohms
Vd 19.2 cu.in.
Fs 27.1 hz
Vas 15.75 cu.ft
Ref 3.9 %
Qts .21
Qms 7.1
Qes .22
Vid .33
Altec Thiele-Small Parameters
I don't have the equipment and software to measure them myself. While it's not expensive, it would quickly become clutter. My audio project list already spans this lifetime and one more. I view these 604 sealed boxes as, once built, being a given that I would then adapt the woofers/subwoofers to. My sense of sealed box characteristics suggests that this isn't unreasonable. I guess one preference here is small as is reasonable while still being able to suppress internal reflections adequately.
Thanks for your help, and take care.
Skip
I'm looking forward to your new project. If you hadn't started me down the 605 OB path, I imagine I'd have built several Manzanitas by now.
In comments from Jeff Markwart's postings and GPA comments, I've gotten the impression that the 604 cone assemblies that GPS sells and uses in refurbs for older 604s match the 604E specs. The following are the 604E parameters from the linked listing for a bunch of Altec drivers.
Xmax 0.15"
Re 7.0 ohms
Vd 19.2 cu.in.
Fs 27.1 hz
Vas 15.75 cu.ft
Ref 3.9 %
Qts .21
Qms 7.1
Qes .22
Vid .33
Altec Thiele-Small Parameters
I don't have the equipment and software to measure them myself. While it's not expensive, it would quickly become clutter. My audio project list already spans this lifetime and one more. I view these 604 sealed boxes as, once built, being a given that I would then adapt the woofers/subwoofers to. My sense of sealed box characteristics suggests that this isn't unreasonable. I guess one preference here is small as is reasonable while still being able to suppress internal reflections adequately.
Thanks for your help, and take care.
Skip
Thanks to fishball79, Pano, and AllenB. All your comments are consistent with my thinking. I would handle the bass with multiple distributed subs in the Geddes/Parham/Lejeune arrangement. The 'little' Altec cabs would then have a chance to at least fit into corners in a new residence if circumstances don't allow our current level of independence.
Skip.... Too bad you don't have the current T/S values.... makes things A LOT easier. One well known knock on the Altec Duplex product line is they vary a lot. Don't know the theoretical T/S for the 604 C/D. Do you have those? My experience has been the GPA 15" re-cone(s) tended to drive up the QTS. So I assume this is due to a combo of stiffer suspension and or heavier than stock cone. Anyway, Very few of the duplexes met their quoted QTS values. Most were in the 0.26-0.34 range. This is important to know so you can properly size and stuff your sealed box. You want to end up with the best group delay, or a final QTC of around 0.9. This value tends to match up well with most sub woofers. My $0.02 worth. Good Luck!
Well, ideally need measured specs, but for high DF systems, ~100-140 L w/2nd or 4th XO @ 80 Hz [depending on power limit required] with minimal [internal reflections only] damping and [room] EQ to fine tune the system.
GM
My thanks to GM as well. Here's a set of measured T/S figures for what appear to be original 604Cs:
Fs = 48 Hz
Qms = 2.74
Vas = 160 liters
Cms = 0.12 mm/N
Mms = 92.5 g
Rms = 10.13 kg/s
Piston diameter = 13.5 inches
Sd = 143.5 square inches
Qes = 0.397
Re = 10 ohms
Le = 2.34 mH
Qts = 0.303
From this thread:
some help with Altec Lansing 604C cab design?
Just a little different, no?
Mine were reconed and remagged at GPA, so they are very likely to be somewhere in what appears to be an ill-defined neighborhood. Sounds like I won't let myself move forward without measuring. Drat!
Skip
Fs = 48 Hz
Qms = 2.74
Vas = 160 liters
Cms = 0.12 mm/N
Mms = 92.5 g
Rms = 10.13 kg/s
Piston diameter = 13.5 inches
Sd = 143.5 square inches
Qes = 0.397
Re = 10 ohms
Le = 2.34 mH
Qts = 0.303
From this thread:
some help with Altec Lansing 604C cab design?
Just a little different, no?
Mine were reconed and remagged at GPA, so they are very likely to be somewhere in what appears to be an ill-defined neighborhood. Sounds like I won't let myself move forward without measuring. Drat!
Skip
Well, the DATS V3 is out of stock, so finding something used or borrowing sounds like my open path. I'll poke around.
Thanks
Thanks