617-8A Enclosure

**Gregor_Germany** · January 20th, 2006, 11:20 AM

Hello everyone!
Glad having found you. Please apologize my English.
Here is my question:
I have 617-8A's and am very happy with them. Until now, because we have moved and my setup does not work as good as it used to. The setup is: The Altecs are each in open baffle supported by a super tweeter and a vented subwoofer. As the new room is much larger and the woofers are a bit too tiny for that, I would like to build cabinets for the 617s. Vented, I believe they should be.
Has anyone made experience? I could build cabinets up to 90 Litres for the place they shall be installed. (Of course smaller cabinets are welcome).

**LICORNE** · January 20th, 2006, 09:40 PM

Hi,

The recommended cabinet is the following.

http://www.lansingheritage.org/images/altec/plans/1970's-lf-plans/enclosures06.jpg

What type of sub do you have?
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Why the need for a second tweeter?

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GM · January 20th, 2006, 10:25 PM

Greets!

These are very low Q drivers, so to get any useful LF output will require trading efficiency for BW with some form of EQ to flatten its in-room response, such as an impedance matching transformer, high output impedance amp, etc.. The theoretical ideal max flat alignment would be a Vb = Vas, Fb = Fs, so it would need to be ~ 221 L and with enough EQ to flatten it in-room, then shelve the HF as required.

For 90 L, much more EQ would be required to flatten it in-room for a Fb = Fs alignment, so tuning it to a higher Fb will be required for a similar amount of EQ in the midbass and it just gets worse as the cab 'shrinks' in size, so you quickly run out of linear excursion without a big box to offset it.

Anyway, until you tell us what sort of minimum performance you want from it and any limiting cab dimensions, I can't be more specific.

GM

**LICORNE** · January 20th, 2006, 10:37 PM

Hi Gregor,

GM is right 3Cubic feet is a bit small. I'm no cabinet designer . My 601 in the 70's were in bigger cabinets.

I'll let him take it from here.

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**Gregor_Germany** · January 23rd, 2006, 07:47 AM

Thank you very much for the detailed replys.
I do not really need the extra tweeters, but I am still able to hear very high frequencies and the 617s stop rather early up there. I like it more that way.
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The woofers are 10" Ciare PA (Italian) and chosen for their ability to play in tiny cabinets. Now with my new living circumstances they do not suffice anymore; maybe the old listening room had some resonances that supported them gladly.

There could be another possibility for me; I could build bigger cabinets for the subwoofers, maybe the problem is already solved that way.

The speakers are built-in in a shelf made for lp records. This is, why I can only use one ore multiple cases from the shelf to build an enclosure. Each case has dimensions of 14.5" width and height, depth can be made to 18" max.
That way I can achieve an inner volume of 184L max. for the enclosure, when using four cases. I do not really enjoy this thought, but if it is the only way it must do.

The subs should have opulent dimensions with two cases; so this might be the first thought... Please let me know what you think.

**Gregor_Germany** · January 23rd, 2006, 08:08 AM

This is where they are and shall be built in.

**LICORNE** · January 23rd, 2006, 02:19 PM

Hi,

This concept exist in 15" components.

You could extrapolate to 12 " and change your sub for a 12 " Altec Woofer.

Please see model below 44.69" tallx24.80"widex18.50"deep.

http://www.geocities.com/rafaleconve...?1138028493020

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**Gregor_Germany** · January 25th, 2006, 11:48 AM

Hi Convergence,
downsizing this will cause other problems not calculable; although this looks interesting. The thought of an ALTEC 414 was already there, but I presume that building one larger cabinet for the 617 will be the best way. Is the 614 cabinet the one and only perfect match for the 617 or is it a cabinet used for many different speakers as I saw some 12" bass speakers in them?
The 614 cabinet has about 110 L. GM speaks of twice as much volume.

Regards, Gregor

**LICORNE** · January 25th, 2006, 12:30 PM

Hi,
There is a cabinet design with the baffle opening
off center to eliminate stading waves.The port hole is a snall box. Unfortunalety I don't have these plans anny more.
Perhaps someone else in this forum can help you.