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

[joes bakery]

Hi,

This will be my first attempt at putting some speakers together and I'm stuck already ..... in order to use a pair of 414-16b (16 ohm) with a pair of 902-8t 511b (8 ohm), what is required, can this be done w/o bi-amping?

Thanks in advance,

Joe

[gdmoore28]

Hi Joe -

First, may I suggest that you post your question to the Altec User's Group? There you will have a devoted group of Altec experts (I am not an expert - only a tinkerer!) who can give you very specific information regarding your build:

http://www.hostboard.com/forums/f700...ers-board.html

For a very quick answer to your question, however, yes, you can absolutely use your 414s and 902 in a very nice combination without biamping. Following usual convention, you could wire the two 414s in parallel (plus to plus, minus to minus), which will yield an 8 ohm resistance. Of course, you will need to either build a crossover network, use an existing Altec design, or purchase a similar design from any number of reputable suppliers. (Be sure that you do not use your 902 drivers without a crossover!)

(Keep in mind that everything I'm telling you is not the BEST way to do your build. Avid builders will go to great lengths to measure their driver's frequency response, resistance profile, Theil/Small parameters and a host of over specifications in order to tailor their crossovers to their specific drivers in their specific boxes. I'm assuming that you are not at that level yet. So, my suggestions are "ballpark" examples intended to get your system functioning. As your knowledge and experience builds, you will be able to make better components.)

If you intend to build your own crossovers, there are a number of on-line calculators for that purpose. If you want to purchase a ready-made crossover with no need to replace the aging capacitors in an old Altec network, you can obtain a very rudimentary crossover from dealers such as Parts Express. Their PXB2-800, for example (http://www.parts-express.com/eminenc...00-hz--290-632) would get you into a reasonable crossover range for the 414/902 combination. You will need to also install an "L-pad" control to adjust the volume of your 902 horn drivers. They are much more efficient than the woofers and will be considerably louder, so they will need to be attenuated. That's what the L-pads are for. For example: http://www.parts-express.com/parts-e...8-ohm--260-262

If you do not already have an enclosure for your speakers, you will need to build a pair. Altec built several variations on approximately the same components you have, so building the boxes will be much easier for you. This site has a good compilation of Altec enclosure guides: http://www.lansingheritage.org/html/...ltec-plans.htm

There are, of course, multiple other issues to consider in your building project, and there are many Altec enthusiasts ready to help you thru the issues. Again, I would suggest starting a new build thread on the Altec User's Group site. You will have at your disposal a great wealth of knowledge in all things Altec.

I hope my suggestions will serve to give you a starting point from which to design your new build. Read all you can regarding these speakers. Build up as much knowledge as you can to make your first effort a successful one. Most of all - HAVE FUN!

GeeDeeEmm

[joes bakery]

gdm,


thank you for such a detailed response, I really appreciate you taking your time to help guide a rookie. I am going to spend a little time researching and then I'm sure I'll will seeking more guidance. Thanks again.

[gdmoore28]

gdm,


thank you for such a detailed response, I really appreciate you taking your time to help guide a rookie. I am going to spend a little time researching and then I'm sure I'll will seeking more guidance. Thanks again.

You are quite welcome. If you would like, feel free to PM me and we can go into much greater detail. I'll be happy to take you as far as I can with my current base of knowledge. Once we've gone as far with your project as I feel competent, I can hand you over to some folks with much greater Altec knowledge than mine.

Looks like your next step will be in building your cabinets, an area that I have a good bit of experience with, so if you need help there, feel free to PM me.

GeeDeeEmm

[Earl K]

I'm not sure what components you actually want to pair up.

A single 12 with a 511b/902-8t combo ? ( or a pair of 12's with the mentioned horn/driver combo ? )

If it's just a single twelve then I would encourage you to acquire another pair of 16 ohm 414's ( b,c or e type ) if you're set on using that large horn.

Alternately, lose the 511b ( & replace it with a more modern waveguide driven by that 902 ) and then pair it with the single 414 .

[joes bakery]

I'm not sure what components you actually want to pair up.

A single 12 with a 511b/902-8t combo ? ( or a pair of 12's with the mentioned horn/driver combo ? )

If it's just a single twelve then I would encourage you to acquire another pair of 16 ohm 414's ( b,c or e type ) if you're set on using that large horn.

Alternately, lose the 511b ( & replace it with a more modern waveguide driven by that 902 ) and then pair it with the single 414 .

thanks Earl,

since I have 2 pairs of 414-16b's, I suppose I ought to go that route, I have nothing in the way of crossovers and would like to know what is the absolute best way to go about this to obtain the best sound, in your opinion.



thanks

[Ed Kreamer]

I have had the pleasure of building several speakers using the 414 LF, and I have found a single 414 lacking in low bass. Disappointing as a matter of fact. However two 414's will give good low bass, and retain the excellent mid bass and mid range of that speaker. Altec built and sold the 9844 Monitor speaker and a twin, the 843 Malibu, and they were very satisfactory. They also built the 9849 using a single 414 but it would only go down to about 50 hz. If you have 2 pairs of these things, I would recommend you use 2 414's per box, in a shared enclosure. You will have to pad down the HF, and you will have an 8 ohm LF section so you can use a pre-made crossover as gdm suggested, with out modification.

Good luck and have fun.

Ed

[Earl K]

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 ).

[Ed Kreamer]

Earl,

The 843 had a volume of about 7.4 ft3. The one's i built were ( I think ) about 6ft3. Tuning in those dark days was pretty much what ever the free air resonance of the driver was. I this case around 25 Hz. ( winisd gives a long banana curve for this driver with 30hz being 11dB down of course this was not available to us in 1973.)

They sounded pretty good, although I had no way to measure it and it had considerably better bass than a single 414. They had a bright and clean sound and weren't boomy at all. I had the help of the Altec commercial contractor in Seattle at the time a fellow named Bob Munger. I crossed them over at 800Hz using the standard Altec crossover. The HF driver was the 806, and the horn was the 811b.

[Earl K]

Cool info Ed, Thanks !!

[joes bakery]

wow .... you guys are great! never in my wildest dreams did I think there would be so many variables in the process of making a speaker great! I keep on reading and rereading and each time I feel a little less lost ..... barely. couple of questions;
1) does pad down refer to lpad?
2) earl are the links that you have provided the right way for me to go
3) does the enclosure size include horn in enclosure?


Thank you GDM, Earl, Ed!



Marty aka "joes bakery"

[Earl K]

Marty ( Joe ),

Where are these ( new project ) speakers going to be used ?

ie; in a Home HiFi listening environment or ( some sort of ) Commercial use (eg. live music at a Coffee Shop/Bakery) ?

"Home Listening" demands a different set of crossover parameters ( as well as box tuning ) .

The Altec 9844 was a speaker meant for the commercial install market ( sound reinforcement ) and had a pretty basic crossover designed for max SPL ( so, it was not that "easy listening" of a speaker straight out of the box, IME / though Altec components typically have attractive HiFi possibilities ).



PS; yes, "pad down" might refer to adjusting the variable Lpad ( to the left, usually ) // or // simply the act of wiring into the line, a pair of resistors ( arranged in an "L" configuration ) meant to attenuate (pad) the signal strength.

[joes bakery]

Hi Earl,

100% home listening, I have an open floor plan listening area of about 25' x 20'. I am unsure of what design I like better, stacked 414's like the malibu design or s x s like the 9844's .... does either affect the listening quality? 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

[Earl K]

Each arrangment ( vertical stacked or side by each ) has their own advantages .

FWIW ( & IMHO ), it's harder to create an aesthetically pleasing look with a @ 24" wide horn over a 12" wide twin woofer stack.

The 9844 was a very industrial looking box. Side by side can be executed much better than that .

Here's a 1959 pic for an ancient Altec 830a( twin15 plus 511 ) that is modern danish ( if anything ).





How are your woodworking skills ?

[Ed Kreamer]

Hi Marty,

If it were me, I'd pretty much build in the style of the 843 malibu. (sorry Earl, great pics by the way ) It would give you a smaller footprint, and raise the HF closer to ear level. I prefer having the HF at slightly above ear level. As far as tuning, I would tune it around 25-30 Hz.when that is done, the response will begin to sag sooner, but it is a gentle slope and depending on the type of music you listen too and room acoustics it may not be noticeable. The plus side is better low bass. Remember that you can always re-tune the box. Do you have winISD? If not, you can download it for free and it is very useful.

A book you should get if you don't have it, is DR. Floyd Tooles book on Sound Reproduction. It is not difficult to understand and you will gain a lot of practical knowledge, mostly on sound and setup, not so much on speaker design Some of his talks are also available on youtube. It will dispel a lot of nonsense. But what do I know? I'm just a classical musician and a retired beer and wine salesman.

Hope this helps

Ed