using 414-16b (16 ohm) with 902-8t 511b (8 ohm)

[joes bakery]

Hi,

I have a MacBook and I don't think winISD is compatible as I cannot seem to download it. If I found the specs on the 843 malibu's and built similar would it put me in the ballpark. Should I go ahead and order the parts that Earl has outlined or was that more suited to a night club type set up, rather than home listening?

I would like to achieve the better low bass offered by tuning 25-30Hz ... what I am still not clear on is, HOW do you tune, is it by cabinet size/vent?


thanks everybody

[Earl K]

Hi,

I have a MacBook and I don't think winISD is compatible as I cannot seem to download it. If I found the specs on the 843 malibu's and built similar would it put me in the ballpark. Should I go ahead and order the parts that Earl has outlined or was that more suited to a night club type set up, rather than home listening?

I would like to achieve the better low bass offered by tuning 25-30Hz ... what I am still not clear on is, HOW do you tune, is it by cabinet size/vent?


thanks everybody

RE; ordering crossover parts.

The eminence can be used for HiFi / with the provisos mentioned ( Lpad, HF correction/restoration across the pad ) .

I would first price out a few alternative networks ( can you solder ) ?

Here's a good one.

[gdmoore28]

Ed mentioned his tuning at 25Hz compared to a later winisd 30 Hz, is this box tuning?, if yes how is this established, sorry probably a dumb question but I do not know.


Thanks,

Marty

Marty, the "box tuning" (Fb) is determined by the size of the vent (or tubes if you so choose) which is determined by the resonant frequency (Fs) of the speaker and the size of the enclosure. You can determine the correct size of the port by either using one of the on line enclosure calculators, or Altec's published chart which is somewhat less accurate, but is a very good starting point:

http://www.lansingheritage.org/image...ure/page04.jpg

You are making some very good progress. You absorb this information much faster than I do. Good going!

GeeDeeEmm

GeeDeeEmm

GeeDeeEmm

[gdmoore28]

Ed,

What enclosure volume to you recommend for a pair of 414's ?

And what box tuning ?

The Eminence PXB2:1K6 is a reasonable 2-way crossover ( 3 pole over 2 > similar in this regard to the Altec 1201/M19 network ).


This is available here ( if the poster is living in Canada ).

- One must add an 8-ohm ( variable ) Lpad ( to attenuate the horn ) like this one from Q-Components.
- One will then need to add back the HF frequencies ( after the Lpad attenuates the horn output ) by wiring something like a 6uF capacitor across terminals 3 & 2 ( of the variable Lpad ).

- I've determined ( for my own satisfaction ) that this network was designed for an optimal woofer load of around 7 ohms ( straight line resistance ).
- That means adding an impedance equalizer ( Zobel ) consisting of something like ( a 7.5R resistor wired in series with an 18uF cap ), the combo then wired ( paralleled ) across the woofers terminals ( see the pics ).

Excellent information and recommendations, Earl. Thanks.

GeeDeeEmm

[joes bakery]

GDM, Earl/Ed, when I look at internal pictures of the 843 malibu's on google images I do not see and port or venting, unless the venting is just off to either side of the horns .... am I missing something, or does copying from the plans Earl provided ensure that it is at the preferred 30 Hz?

Earl, yes I can solder and I have a friend that could guide me I'm sure, the schematics confuse me some, I like learning though. I'm beginning to think that for my first go around I might be best to try and keep it simple and down the road gather a little more knowledge and hotrod them some if they don't sound great.

Ed, I listened a little on youtube and will start hunting for the book.



Thanks,

Marty

[Earl K]

Regarding the woofer layout ( vertical or horizontal );

I'd recommend ( first making at least 2, 3.5cu' test boxes tuned to 30hz ) so that the two configurations can be tested ( in room ) to see which offers the best performance ( stacked or side-by-each ).

I think it's folly for any (DIY) newb to move forward without first going through a testing routine.

[gdmoore28]

GDM, Earl/Ed, when I look at internal pictures of the 843 malibu's on google images I do not see and port or venting, unless the venting is just off to either side of the horns .... am I missing something, Thanks,Marty

Marty, You guessed correctly. The spaces to either side of the horn serve as the vents in the Malibu enclosures. Your idea on building a quick and dirty set of enclosures won't hurt a thing other than being less than optimum. The only thing to consider here is that you will be spending money on material anyway, so why not do it right the first time out? You may be tempted to build the temporary boxes and leave it at that, but you will always have it in the back of your mind, what if you had done the suggested enclosures instead? You know which way I would lean.GeeDeeEmm

[joes bakery]

GDM,

thanks for your thoughts, you are 100% right! and I agree whole heartedly in regards to the cabinets, I should be clearer in my writing, I was thinking of components and that if they weren't where I thought they should be sound wise, they could be altered. I love creating with wood, they will be done right, strong and purdy

Would the Altec recommendations that Earl provided below be for a single 414 and if so, would I simply dbl for 2?




thanks

[gdmoore28]

GDM,



Would the Altec recommendations that Earl provided below be for a single 414 and if so, would I simply dbl for 2?




thanks

Marty,
Exactly which post number are you referring to?
GeeDeeEmm

[joes bakery]

Sorry GDM,

Post 21, regarding enclosure size for 414 8b.


thanks

[Earl K]

Sorry GDM,

Post 21, regarding enclosure size for 414 8b.


thanks

Yes Marty, that Altec info ( within post #21) is per speaker. So make a box that's 6.5 to 7.5 cu' .

Since the 511 horn is ( I believe ) wider than the posted 843 plans , you might consider just putting it on top of the box.
- You could also simply widen the box a bit to accommodate the 511 ( as long as the internal volume doesn't go past 7.5cu' .

Regarding box tuning, your best off including 2 ( to 3 ) ducted ports ( 3 to 4" inside dimension ) cut to length to tune the box to @ 30 hz.
- Place them near the bottom of the box.
- Off-hand, I don't know what length duct to propose.

[gdmoore28]

Since the 511 horn is ( I believe ) wider than the posted 843 plans , you might consider just putting it on top of the box.

The 511 horn is 24" wide.

GeeDeeEmm