Cabinet for 605A

[LICORNE]

The Altec Duplex came about from the idea to get a compact speaker for recording studios.The Shearer Horns were the first speakers invented for theaters. Then the Iconic 6 Cu Ft 2 way 800 hz xo was created. And the Duplex with 612 cabinet the final compact design. The small horn in the duplex makes the xo to be at a higher level
1500 hz.

So you must compromise . A&M recording studios used 2 604 with 2 416 per channel in an infinite baffle enclosure above the mixer. This technique is still used at some recording studios.

So if your using low power tube amps you will have to do some calculations as to the size of the cab as said above.

..............

[speakerdave]

Originally posted by GM:

FWIW, I prefer EBS alignments with net Vb = ~Vas/Fb = ~Fs, making this one around 15 ft^3/30 Hz. [/QB]

<font size="2" face="Verdana, Helvetica, sans-serif">Hi,

Could you unpack this a little? I don't see how you make the numbers work.

Thanks,

David

[GM]

The specs I have is Fs = 30.3 Hz, Vas = 14.33 ft^3, so once you add in the driver and bracing it's ~15 ft^3.

[speakerdave]

Originally posted by GM:
The specs I have is Fs = 30.3 Hz, Vas = 14.33 ft^3, so once you add in the driver and bracing it's ~15 ft^3.

<font size="2" face="Verdana, Helvetica, sans-serif">Ah, you mean you like to build a cabinet equal in volume to Vas and tune it to the FAR (Fs)? Is that done by making an unducted port equal to the effective cone area?

David

[GM]

FAR? Frequency At Rest? Anyway, 'Fs' as in the driver's resonant frequency and yes, make the cab's net Vb ~ = to the driver's Vas.

The vent size required is a function of the cab's net Vb and the amount of pressure the driver will potentially exert on it at Fb and not audibly compress ('chuff', 'whistle'). For a 604E this will be around the size cab you built IIRC and the tuning I suggested. Anyway, close enough that only fine tuning the vent to the driver's actual Fs for SET use may be required.

[speakerdave]

Originally posted by GM:
FAR? Frequency At Rest? Anyway . . . .

<font size="2" face="Verdana, Helvetica, sans-serif">You know very well it is Free Air Resonance. I do not see why I should be mocked for using this old terminology. I've used it, in fact, to see what you would do. I could say that it means something else which is very important to me, and that is that I am, Frankly, Always Readable, which is more than I can say for you.

While I appreciate your technical knowledge and the freedom with which you share it, I often find your posts to be so dense that it makes me wonder if you are really feeling uncommunicative most of the time. And I don't think I am the only one who finds you difficult to understand, since I've seen others ask for clarification often.

It just so happened that I read your sentence as meaning that the box volume equals the Vas divided by the box resonance equals transducer resonance, which is exactly what you said algebraically, though it makes no sense technically. Your penchant for hyper-abbreviated expression might have been appropriate at some time in an engineering office with like-minded colleagues, but on these forums it is nothing more than a form of snobbery and leads to confusion much more often than you would likely care to acknowlege. And I've noticed that when you are asked for clarification, often you are unpleasant about it, as you have been just now. Just as I predicted you come on as if you are the only one who is entitled to an idiosyncratic argot, and that tells me that you do what you do intentionally, and I have to tell you, it is really such a bore.

Sincerely,

David

[bfish]

Are GM's posts often hard to understand? Durn tootin'!

Are his answers satisfactory to those seeking a quick and easy reply? Probably not.

Where do I go first when faced with unanswered questions? GM's archived posts.

The number of times I've had to hit the books to get a better understanding is a near match to his post count. The result? A better understanding.

(FWIW, I understand free air resonance, but didn't have a clue what FAR meant either.)

Does GM mean to be a smart-a? Only when it's very obvious, which is seldom.

A relatively unknown bit of trivia, and something he won't tell you himself...GM hasn't had a home stereo to enjoy for quite some time, choosing to prioritize financial obligations in a very honorable way. I've tried to help in that regard, but he has pride, and I respect that. I know there are many times he answers questions when he doesn't feel well, proving a selfless desire to help any that are willing to help themselves a little.

Lordy, lordy, if anyone deserves criticism for their forum demeanor, it's me! It would largely be a waste of time though, I yam what I yam, and I know what I yam...kuh-kuh-kuh-kuh.

[speakerdave]

Originally posted by bfish:
A relatively unknown bit of trivia, and something he won't tell you himself...GM hasn't had a home stereo to enjoy for quite some time, choosing to prioritize financial obligations in a very honorable way.

<font size="2" face="Verdana, Helvetica, sans-serif">What?

What do you mean? I was under the impression he had two 20 cu. ft. subwoofer cabinets with two 515's each! And whatever else.

One can imagine all kinds of things. However, even if a person is a bankrupt he is entitled to some personal possessions, which I think could include a not-too-valuable stereo. But we could lend him stuff, anyway. Now that it's out in the open, we should do something about it.

I acknowledge that I've learned from him (that is, if I understood him correctly), and others have said he has helped them design their speakers, why would he not accept something in return, or a similar act of generosity? Between us all we've got to have enough surplus gear sitting around to put something together, if that is what is called for.

If someone knows him and is near him, who would organize it, let me know what is needed. How much space does he have? Maybe I could lend him a pair of speakers He'd find acceptable in an emergency (that is, so he wouldn't feel like he had to--and couldn't--sell them to get money for whatever it is you referred to that he is doing financially).

David

[bfish]

Originally posted by speakerdave:
...I was under the impression he had two 20 cu. ft. subwoofer cabinets with two 515's each! And whatever else...

Now that it's out in the open, we should do something about it...

<font size="2" face="Verdana, Helvetica, sans-serif">I believe it's the whatever else that's lacking, i.e., electronics/source(s).

I agree. I'll start a new thread. (Sorry GM, guess you'll have to sue me!)

[donaldpatten]

electrovoice1
I have a pr of 605As in Altec Carmel cab's.
These cab's are 6 cu ft and "leaky" around the baffle board. They wrapped the grill cloth around the baffle board without sealing the joint. I caulked the joint, and ported the baffle board with a 10 x 2 " slot.
Bill at GPA reconed & remag'ed them giving them a 22 Hz free air res. I retuned the cab's with a tube 10 x 2 x 4" deep this gave equal peaks in the Z curve ( the old fashion way )
My room is 8 x 13 x 21 and this combination gives me usable resp to around 32 Hz.
Don