Altec Model 15 project

Just for fun I ran the woofer only in the Model 15 box. Horn and crossover plate installed. Taped off the driver mount to horn. The other speaker has the same woofer(Altec 412c} but in the smaller Heathkit AE-40 cabinet. Turned the eWave section down in the AE-40. Sounds much happier in the larger 15 cabinet. The bi-flex plays higher than you would expect. The center of the bi-flex measures 5 1/2 inches. Anyone know when a 5 1/2 inch speaker starts to "Beam" ? Graph is unweighted pink noise taken close {8 inches}with a Dayton mic on my phone. The graph is always sloped when unweighted . The second graph is more accurate .
 

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Cheap Chinese diaphragm installed. Had to drill the Chinese knock off. The pins were in the wrong place. Output very low compared to the woofer. The woofer that the Model 15 came with had 93 db sensitivity. The 412c is much more efficient. Running the woofer full signal. I have Radian diaphragms on order and they may make the difference.
 
The Chinese diaphragms for Altec are worth less than the time it takes to install them, absolute garbage. Regardless of the number of posts about them, people will still buy them. I am reminded of a long time member here and a quote of his about manhole covers.
 
I knew they were crap but wanted to play with mounting a diaphragm. The radian diaphragms are in now. Big difference. Only had a few minutes to listen to them. Will know more when I get home from work. The woofers are run full range on the original crossover. I may need to trim the upper range of the 412c. Plays into the treble range 5000 Hz.
 
412c data1.jpg
Most importantly they will both sound the same and have equal sensitivity.
Here are some graphs of the two. The problem is the sensitivity and range of the 412c . The Model 15 crossover runs the woofer full out. I will need to cross the woofers before I know more. I have attached a page for the 421c. This is from the 1966 catalog. Also a graph from the cplipx japan site. I may have to pad down the woofer as well as crossover it. The mid and hf controls on the Model 15 crossover were set to maximum.
 

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Here is a graph of pink noise. I took the sweep very close to each driver(2 inches). The woofer put out as much high frequency as the 802 on the horn. The model 15 uses compensation similar to the eWave. Crossover of the 15 attached. The red highlighted portion sets the crossover range. I think the green highlighted section is the compensation. Correct me if I am wrong. If I lessen the compensation and let the 802 play more open would that help? The graph looks good except for the upper range. If I can get the 802 to "keep up" this will sound better. Please any and all recommendations welcome.
 

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I think it would be worth your while poking around Josephs ( JE Labs ) Blog to see what you can pick up there in the way of his ideas/experience for taming ( & then merging the sonics ) of your components .

My perspective is you need to "play" a bit with LC components to finally arrive at a crossover topology that will work best for you.


:)
 
My perspective is you need to "play" a bit with LC components to finally arrive at a crossover topology that will work best for you.
Thanks for the link. I have been reading up on the Altec options for crossovers. I have some bi-amp terminals. The plan is to replace the original Altec push terminals on the bottom. The more I listen to the current setup. The more I appreciate the details conveyed by the Altec woofers/fullrangers.
 
Katalyst,

You might have come across this ( 32343 ) network in your search's .

Altec32343.png


It's usefulness is best defined by the fact that it nicely maps-out the overall signal flow and layout of the crossover ( this network was used in the Altec 9849 > which included the bent-horn 32b/802 combo and a single 414 ) .

Note that the inductor values are missing ( they've never been measured by those who own this crossover ), plus VR1 would not be a 100K Lpad ( I figure it's safe to assume it would be 8 ohms ).

You might consider building ( at least ) the HF portion of this network .

Here's an XSim simulation for the HiPass portion of the above network ( using guessed-at coil values ).
- The variable Lpad is wide open here ( the shaded-blue area ) and might be omitted in a real build.

Altec_32343_Network_.png


I had to create a .frd file for the simm of a 802-8G on a 32B horn ( traced from an old polar response file that was once accessible over at Hostboard ) .
- I used my own .zma file created with my 802-8T driver attached to a 811B style BiRadial.

There's an element of fiction to this ( since these aren't my horns or actual FR measurements ) > still, it's a reasonable place to start for the design of a horn/driver HiPass .

:)
 
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Sweeps (9).JPG EarlK thank you for the insight. The goal of my mods are to keep woofer doing the vocals till at least 2.5 k maybe 3 k. Then bring the 802 driver on the 32 horn in. When I get the bi-amp terminals installed. I can try adjustments to crossover out side the box. If you would be so kind would you send the .frd file for the simm of a 802-8G on a 32B horn. I will download the XSim software and start to learn the nuances of crossovers. Sounds like fun to me. Attached is a graph to show the difference in the horn vs woofer. Looks like 10db above 5k to me.Sweeps (9).JPG
 
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Hi,

Here's the whole file ( zipped ).
- the 802's .frd and .zma files are already included within the driver icon.

I've already moved the crossover point up to around 2.5K in this version for you.

Just unzip this and open it within XSim to play around with the values.


:)
 

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I've already moved the crossover point up to around 2.5K in this version for you.
Thank you for making this easier for me. Much appreciated . When I get time to play in XSim I will report back. Thanks again.
 
Note that the inductor values are missing ( they've never been measured by those who own this crossover )
I have a cheap LCR meter, and a pair of 32343 networks that aren't doing anything at the moment. It'll take me a couple days as this will first mean locating both the LCR meter and the networks.
 
I have a cheap LCR meter
The meter I have is also cheap. I tried to re-create the Model 15 in XSim. The values were set at optimum from the attached schematic from the web. The values for the lpads at optimum settings were added to the resistors to simplify the process. This is my first time using XSim.
 

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