a cabinet question

[klausesser]

Hello!

I?m struugling with the question which kind of cabinet i have with my 604E/16Ohms.
The cab. was build by a stage-pro in Munich/Germany for the 604E.
I wonder if it?s a 620 or not - it seems to be deeper:

95x59x47 (inner size) - which is about 9,2cub.ft
the port (no tunnel) is 45x12cm
It houses - as said - a 604E (white/grey basket) and a 1500A network.

I?ve got two EV XEQ2 two years ago and leveled the time-delay by using a MLSSA system.

So far so good - sounds great with two switching amps. Very fine-structured, light, subjectively "fast", good bass.

But now i want to have it using a passive xo alternating for trying some more and different amplification - my AudioResearch D76A and a Shindo monotriode.

Jeff Marqwart - thanks again, Jeff - sent me shematics of his xo which includes a timedelay of a 605 with 604E cone.

The question of my cabs is still unclear to me - and thus the influences to a passive xo . . . are 9,2cubft too much?

Bill (Fortier) - hi Bill!! - gave me some clues tomes ago, but he has 8Gs and no E.

Well, any ideas about passive xo in general and Jeff?s in special combined with the 9,2cubft housing?

greetings from Germany, Klaus

[GM]

Greets!

Can't find my notes on the 620 at the moment, but you can figure it out yourself: http://www.lansingheritage.org/images/altec/plans/1970's-lf-plans/enclosures07.jpg

Anyway, your cab is tuned up around 50 Hz, so while it may have a pleasant, 'toe tapping' bass, the cab is much too small and tuned too high to get all the LF performance this driver is capable of.

A passive XO will add some much need series resistance that will allow a lower tuning (smaller vent area) to be used without loss of perceived bass output, yet better damped ('tight' sounding), though the HF horn will probably need more shelving to maintain tonal balance than you're currently using.

GM

[klausesser]

Hi GM!

Thanks for replying so quick! You really mean 9,2cubfeet is too small? Never heard about a bigger cab from Altec - besides of the Urei with additional woofer.
Good Lord - that?s 263Litres . . . - but you?re right with the bass!
I LOVE these 604E! Very smooth and clean and natural mids and highs - i prefer clean and "light" basses, where you can feel the wooden corpus of Ray Brown?s instrument or a Kodo-drum.

I guess you?re also right with the passive xo and an optimal matched port . .
Have to re-check Jeff?s schematics and just go by try and error the rest of the way . .


greets from Duesseldorf, Klaus

[GM]

Originally posted by klausesser:
Hi GM!

Thanks for replying so quick! You really mean 9,2cubfeet is too small?

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

You're welcome!

Yes, if you want to take maximum advantage of its low Fs.

GM

[klausesser]

Hi GM!

"Yes, if you want to take maximum advantage of its low Fs."

well . . . any suggestions? - Maybe i can add some volumina to the cabs . . or to my living room . .

best, Klaus

[GM]

Greets!

Well, a driver wants to 'feel' a matching air load, so increasing its Vb to at least its Vas spec is what I do, then tune it to the driver's Fs and use some form of EQ to individually flatten each one in-room. Obviously, using measured specs is best, but assuming the published specs are known to be reasonably accurate, these values are close enough IMO.

GM

[klausesser]

Hello GM!

You?re right again - i?ll give it a try. Somewhere i have all the data of the 604E - i remember the VAS is really huge . . .
Theoretically it even active should work better . .
Tricky: the 604E is pre-tsp . .

best, Klaus

[klausesser]

Hi BFish!

"Which can be a good thing if it leads you to measure the parameters of your drivers on hand and design to them instead of a generic data set."

i intended that anyway - they?re about 40 years old . .

best, Klaus

[bfish]

Originally posted by klausesser:
...Tricky: the 604E is pre-tsp...

<font size="2" face="Verdana, Helvetica, sans-serif">Which can be a good thing if it leads you to measure the parameters of your drivers on hand and design to them instead of a generic data set.