I built a pair of these cabinets back in 1977 , And I thought the group would like to see
A photo....GC
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I built a pair of these cabinets back in 1977 , And I thought the group would like to see
A photo....GC
My kind of duplex!
GM
3/4 in. baltic birch was used in the construction of these 21 cubic foot cabinets.
The center of the horn is 45 in. above ground, Which I find is A nice level for the 604's
...........GC
Good size, I recommend up to ~27 ft^3 if driven with a high output impedance. I prefer the HF somewhat above my head also same as we get at a live venue.
GM
I wil dig up the inside dimensions of this cab and post........Up to 27 cubic Ft. ?
What about WAF....... Oh , I built these before I was married...........GC
The internal dimensions are; 33 inches across the face
21 inches deep
53 inches tall
The port dimensions are; 6 inch dia. PVC pipe, 12 in. long
Braces from top to bottom on the back, sides and A "T" shaped brace below the speaker.
God I bet those sound good!!
They make those 604's look like 8 inchers!!! I bet they sounded Fantabulous. Awesome.
Yeah, as you probably know, Qts (effective motor strength) dominates cab design, so ~double Qts with a matching impedance amp and for a maximally flat alignment as might be required in a large and/or 'open' format room, net Vb increases ~10x and Fb drops ~ an octave. With HE driver specs such as the 604, this can get closet size with my personal biggest being 30+ ft^3.Quote:
Originally Posted by 604man
I guess I was blessed WRT 'WAF' since I had no clue what it or SAF, S.O., SWMBO, etc. meant when I joined the early audio WWW BBSs. My smallest main system stereo speakers were A7s in a 10 x 10 ft^2 bedroom as a teen and the three wives (not at the same time), several live-in GFs and numerous 'miss right now' GFs that filled in between never seemed to care about how big they were other than noting their size or complained about all the experimentation that went on. I did normally keep them hidden behind 'full height' room decor matching screens mostly to protect them from kids/pets and the fact that I didn't much care to look at utility cabs with exposed horns any more than they probably did.
I also had them help 'voice' the various iterations since they not only had better HF hearing, but I'd learned early on that they flat out enjoyed listening to their music loud on them (louder than I preferred in some cases) when they had tailored them to a female's to offset their unique hearing priorities somewhat; so much so that they bragged to their GFs/co-workers about them, making for a semi-constant flow of them and their BFs/husbands/kids over to audition their preferred music. This often led to me bartering speaker designs/builds for a variety of services back before the IRS started taking a dim view of such so-called tax evasion, so family income didn't suffer, ergo nothing for her to justifiably b!&$h about.
GM
In 1984 I was running a Citation II with these speakers, the high-Z output made the speakers sound boomy in the small living room of the house I was living in at the time, So I went back to SS power ...I am on my third pair of cones with these speakers !
I will post more photos of these cabinets in the next few days.
WAF.. Alot of women will take retribution on your HIFI,radio / test equipment cars,motorcycles, tools,boats & bank acount...I never had a problem but quite A
few friends of mine have !
........GC
Wow they are almost the same dims as my new cabinets I'm building. 36W x 32D x 54HQuote:
Originally Posted by 604man
Port dims 6" PVC 4" length ;) But mine are just LF boxes for my dual 416's. My box is triangular though as they are corner boxes.
Do you know the tuning of your box ?
http://www.hostboard.com/forums/hbmc...2010/11/39.jpg
As recall, Vb is to be tuned to speaker free air resonance 25hz.....At the time I made the
PVC duct, I made it long to be trimmed if needed....It sounded so good I left it....... later
I added A coupling / splice to extend the duct to facilitate testing / tweeking. I should
test the Z and check the two resonance peaks...I will take photos..You will enjoy you
cabinets what is the Vb ??? ........GC
FWIW, it calcs to ~14-15 Hz as a simple BR depending on the amount of internal bracing which is a bit too low for a duplex in theory, but real world performance trumps it of course.
GM
This is really only true when driven with a high system impedance (Qt). When the driver's Qts dominates system Qt, it also dominates cab alignment.Quote:
Originally Posted by 604man
GM
this is really great info ,although have used the 604 in max 9 cft boxes and 6 cft boxes, was always afraid of heavy TT rumble , but now with big digital bandwith every one should try it once.
how inert should the cabs be to avoid internal mumbo jumbo
thanks and a happy new year
It's not about how inert it is, but how stiff it is since it's a lot easier to push the cab's Fs above the intended BW than below it to ensure it can't be excited. I mean if you want to make it inert enough to push its Fs below the intended BW, that's fine, just understand it needs to be built out of many inches thick concrete or similarly massive material and damping TT rumble will probably require walls built like concrete suspension bridges to get such a low Fs damping.
Others have gotten close enough with stone slabs (slate, marble, etc.) over a plywood construction, but they were small speakers with a fairly high Fs, not the low tuned, relative behemoths we ideally need; so using at least 19 mm no-void Baltic or Apple Birch combined with some bracing to tie all six sides together to keep it from 'breathing' will work fine, and while not exactly light, at least it's movable by most folks with a cheap hand truck if there's not a lot of stairs.
Making it some form of TL allows less bracing to boot since its high aspect ratio places most of the resonant pressures along its length, so not as much cross bracing required. Factor in that the bigger the cab, the lower the pressure nodes and very little bracing is required, mostly in the form of ridge boards glued in to break up the large panel areas into a lot of very high aspect ratio strips with a cross brace to do double duty as a motor support.
All that's left then is reflections off the back of the driver, which is easily handled by the standard top, one side and back being covered with insulation to 'taste'.
GM
I just tried posting 5 pictures with text and several replies to posts and *EVERYTHING*
went off to never never land....If you would like photos comments e-mail me @
george_craig@att DOT com
George don't use the attachments, Do you have a Photobucket,Flicker,Picassa, account.If so, just upload the pics to those hosts copy the direct link and then click the insert image link above in the toolbar when replying. You can insert up to 6 images.Just like this,heres the button on the toolbar. :2thumbsup:
http://www.hostboard.com/forums/hbmc.../2011/01/3.jpg
BTW: You don't need that Http:// in the insert image link,paste over or delete that.
I posted 17 photos ; Image hosting, free photo sharing & video sharing at Photobucket
..............GC
Those are very nice boxes, but I think you might need a few front to rear braces. Both of those panels have a lot of big surfaces that aren't tied to anything. OTOH, if they aren't adding colorations, leave them be.
Great job, and I like the adjustable ports.
The internal duct is 10 1/4 in. long , The L & R side braces are 5X3/4X53 in.
The T vertical brace is 5 1/4X3/4X25 in. The T horizontal brace is 6 3/4X3/4X33 in.
The back brace is 5X3/4X51 in. The back mounting frame is 1 1/2X3/4x172 in.
Stuffing is fibreglass, 22 wood screws holding the back panel , internal crossover volume is 3 3/4X4X5 in.
..........GC
If they sound as cool as they look I'm guessing they sound absolutely fantastic.
Subtracting the brace,driver, crossover and duct 6 in. L volumes, I have a Vb of 20.227
cu. ft or 572 litre...Box tuning is 19.04hz.. Response is 10DB down at 20 hz, But given
room gain of 3 to 9 DB up to 12 DB depending on venue to bring the frequency response up.....HTTP://micka.de/org/en/index.php#ideal is the online box calculator... I hope I entered the data corectly.......In spring I will try trimming & tuning the duct.............This is an on going project! 30+ years.
MUCH THANKS FOR GM'S INPUT!
I might add, I am *NOT* a cabinet maker and this was a father & son project (I am the son) And dad was an audio buff from the 40's & 50's. He really liked this project and the baltic birch plywood with its uniformity and constistancy makes construction easy. With the braces installed as shown in the photos, the cabinets are quite stout.
As far as sound , synth, organ, tympani come through with "Presence".......GC
Thanks for posting these photos ! ............GC