Altec 604E in small cabinet...

[Guglielmo]

Hello to everybody,

I am going to get a mint matched pair of Altec 604E so I am looking for a proper enclosure for this glorious driver. I read a lot about "original" boxes like 612 or 620 or DIY wonderful enclosures but in almost all cases the project requires a huge amount of internal volume.

I live in a small lodging so I can't afford a big speaker cabinet thus I need your skilled help to get the better performances even in a small volume enclosure.

First of all my available space would be in a "bookshelf-like" location namely on the upper shelf of a living room furniture. The possible maximum space is 34" length X 12" depth while the height is free even if less than the length.

I read also that this driver may accomplish some new trends like the Open Baffle design with a lot of natural fresh musical reproduction even if perhaps with some bass lacking... This Open Baffle theory could be a good approach for me because I could consider a frontal baffle with the 604 fitted to it and all around a frame less than 12" to allow rear flow of waves against the wall. Actually the enclosure would be an opne baffle C shaped (front baffle with flour wings). By the way the cabinet location on the shelf is in front of the wall.
The other solution may be a classic bass-reflex but I guess that in this way I will have some problem with very limited bass response.
The allowed dimension are to be intended external so it must be considered for internal volume calculation the ¾” wood thickness.
Please may you help me in suggesting the right design for these Altec’s.

I appreciate your contribution!

Guglielmo

[speakerdave]

The 12" space depth for the cabinet is simply inadequate. The 604E unit is 11 1/8" deep itself and must be mounted on the back of the baffle board. A cabinet for any 604 should be at least 18" deep.

If you like the coaxial format I suggest you go with some 10" Tannoys.

[Guglielmo]

Thanks speakerdave!

I realize that the allowed depth is not enough anyway I am fond of 604s rather that Tannoys so I would "challenge" the dimension constraints and try to get out some decent performances... Why do you say that this unit must be mounted on the back of the baffle board? If I cut a precise round notch on the front I may fit this unit on the front like later versions (604 G for instance...). Or not?

[speakerdave]

I like them both, and in that situation I would use 10" Tannoys.

[macaroonie]

I would research the smallest cabinet used by Urei with the 604 and change the dimensions to suit your needs at the same time keep the internal volume the same..

Another idea , do you have corners in the room that you could use ?

[Guglielmo]

... good idea to get UREI similar projects with 604 like drivers ... As far as I know the UREI 811B sports the 15" coax driver and as seen in datsheet the internal volume is 5 cu ft. Following that using Thiele-Small parametrs a good reflex design could be approached, even if the deeper bass are always a mirage

Cheers,

Guglielmo

[macaroonie]

From your description you will be close to the wall so you will get reinforcement from that. Perhaps just build a suitable sealed cabinet and hear what happens , it might be fine with boundary reinforcement. If you leave enough space for a port you can try that if sealed doesn't work out. 4-5 cu ft should be fine for home use as a ' bookshelf ' speaker.

[speakerdave]

The UREI cabinet was designed for soffit mounting and uses a resistive port, which has the effect of lowering the impedance peak around resonance. Making one is a cut and try proposition. There was a construction project article in Audio Amateur in the '70's about a 5 cu ft ducted port cabinet for the 604 8G. This may work if your 16 ohm woofer does not require different tuning. If I still have my copy I'll scan it for you. Failing that there is a book available with speaker projects from that magazine. I'll look later today. That cabinet was good down to 40 Hz but would fall off at 18db/octave below that. It would be worth while trying the sealed solution in a small room, though the fall off would start much higher and there might be some upper bass bloom. 40Hz was often good enough in the days of vinyl. With that driver you have to go almost twice as large to get another half octave.

Are you using small SET amps? You might post your question over at the Altec users forum. There is a cabinet maven there who could systematically address all the complexities, including the implications of impedance matching with the amp.

[Guglielmo]

Thank you spekerdave, I appreciate whether you may find for me that old article in Audio Amateur, this could be useful for my 604E thoughts...

I started to focuses on "real" dimensions allowed by my home location thus I take a classic bass reflex as a model for side lengths. For instance the Klipsch Cornwall "adapted" to my hosting shelf shall be resized and reduced as approx. 32" x 22" x 13". Who knows if this proportional idea works?

[speakerdave]

That's not going to work. The parameters of the e and 8g differ from each other. The box you propose is not the size used in that plan, anyway. I'm afraid I've encouraged you to persist in something that is going to lead to disappointment. As macaroone suggested, make a sealed enclosure of whatever size you can manage and see what it sounds like.


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Thank you spekerdave, I appreciate whether you may find for me that old article in Audio Amateur, this could be useful for my 604E thoughts...

I started to focuses on "real" dimensions allowed by my home location thus I take a classic bass reflex as a model for side lengths. For instance the Klipsch Cornwall "adapted" to my hosting shelf shall be resized and reduced as approx. 32" x 22" x 13". Who knows if this proportional idea works?

[Guglielmo]

... then I realize that the available space in my living room for such a cabinet is not suitable for a proper 604E fitting... For that I would insist in the OB project avoiding too limited enclosure size and relevant bass frequency lacking response. Nevertheless the baffle shall be maximum 35" x 21" and positioned on the longer side on the furniture shelves at more than 80" height (like in studios control room). I fear anyway a bass lacking even if this OB shall be close to the rear wall. For that I am seriously thinking about an helper woofer like in this Jamo model

http://www.jamo.com/speaker-types/fl...ding/?sku=R909

The allowed space on the baffle is just sufficient to host my 604E and another 15" woofer. Then to stay in the Lansing family I would an Altec vintage woofer, may be a 416B in Alnico. What do you think? If this could be a good approach how do I have to connect the woofer? Consider that I will drive the Duplex sections directly from bi-amp set up with active Xover and two power amps (SS for bass and tubes for high). Shall I have to "cut" the bass response of this helepr woofer may be around 100 Hz like a sort of subwoofer or connect directly to bass amp leaving the mechanical frequency cut which is much more high?

I very appreciate your skilled help!

Guglielmo

[macaroonie]

I seriously doubt an OB system will work for you , you are too close to the wall. I think you would be seriously disappointed. A helper woofer will not help unless you can arrange a huge baffle , the cancellation will negate any useful output.

Again I suggest you look at the Urei approach. As long as cabinet volume is sufficient ( 4-5cu ft ) you can change the proportions to suit your space.

Or make your life easy and trade the 604's for Tannoy K3808. or HPD 385. Still 15" but much less front to back , no issues with bass , you will more likely have too much , that is easier to deal with of course.

M

[sean19]

Hi i have had 604s before had them in a 9 cubic feet cabinet that is the recomended optimum size according to altec they sounded great. As far as the crossover its hard to improve on the stock crossover I just upgraded the caps to solen polypropylene caps also changed to better inductors also use the 604-8H med and hi frequency controls on your 604 e crossover and i am sure you will love the result i have heard these speakers in open baffle bass was gone so was a lot of the mid range also heard these in infinite baffle and they were ok but i think they sound best in a ported cabinet more info on the crossover here http://home.earthlink.net/~jmarkwart/ if you can fit the driver in a 12 deep cabinet witch should work will be fine as long as it is a rectangle in shape and not square cause standing waves also carpet padding is very dense makes a great liner for the cabinet