Zilch's AK Design Collaborative - Econowave Speaker

[Rex Everything]

There's a port in M14, no? Perhaps someone can tell us the port dimensions....

From the pictures and the spec sheet the Model 14 is a "vented" cab. Looks like a rectangular port to the right of the woofer.


http://www.lansingheritage.org/images/altec/specs/home-systems/model-14/page5.jpg

 

[Zilch]

M15 uses the same woofer, as I recall, and a round port. It'd be good to know those vent dimensions, as well.

We need the T/S parameters of that woofer.

Otherwise, tuning's going to be an exercise in empiricism using impedance measurements....

 

[Russellc]

Here are a few pics of what I'm going to be working with when the parts come in next week for my EconoWave crossovers.

Moddified ALtec Madrid 872B's

If these trun out to be as good as all the others I'm going to consider finding someone to cut new baffles so the horn is in the cab rather than on the cab. Any suggestions(ie porting.....) the experts here have for this set up will be appreciated.

You might as well be figuring out how to bring wires out from the woofer, and get that part all ready. Then you'll be all ready to hook up when your coils come!:yes:

russellc

 

[Rex Everything]

You might as well be figuring out how to bring wires out from the woofer, and get that part all ready. Then you'll be all ready to hook up when your coils come!:yes:

russellc

I figured I'd just run the woofer to the original input terminals. Then run the wires for the LF from the xover to the terminals. Sound like a good idea?


Is anybody else using the jackgiff pcb boards for there xovers? If so what are you using at the input to the xover? There are two 1/4" holes there for the input connection. That's gonna take some huge wire in the area of 2ga. or so

 

[Rex Everything]

We need the T/S parameters of that woofer.

Otherwise, tuning's going to be an exercise in empiricism using impedance measurements....

I know nothing about this. I'm a complete n00b to speaker building and design.

 

[Zilch]

Is anybody else using the jackgiff pcb boards for there xovers? If so what are you using at the input to the xover? There are two 1/4" holes there for the input connection. That's gonna take some huge wire in the area of 2ga. or so

They are made to accept the PE binding posts. There's also cheap ones available at Radio Shack.

http://www.parts-express.com/wizard...8&FTR=&search_type=main&WebPage_ID=3&x=17&y=9

Ross just ran his wires through the holes and tack-soldered them on the back.

I expected that those who didn't want to use input terminals would screw some solder lugs on at those locations....

I know nothing about this. I'm a complete n00b to speaker building and design.

We're gonna learn, then.... :thmbsp:

 

[Rex Everything]

They are made to accept the PE binding posts. There's also cheap ones available at Radio Shack.

http://www.parts-express.com/wizard...8&FTR=&search_type=main&WebPage_ID=3&x=17&y=9

Ross just ran his wires through the holes and tack-soldered them on the back.

I expected that those who didn't want to use input terminals would screw some solder lugs on at those locations....


We're gonna learn, then.... :thmbsp:

I figured the terminals was the case. It made sense as I didn't notice until I had already placed my order. I'll either just solder the wires through the hole or screw on lugs like suggested.

I'm ready to learn some. Just let me know what I need to do.

 

[Russellc]

I figured I'd just run the woofer to the original input terminals. Then run the wires for the LF from the xover to the terminals. Sound like a good idea?


Is anybody else using the jackgiff pcb boards for there xovers? If so what are you using at the input to the xover? There are two 1/4" holes there for the input connection. That's gonna take some huge wire in the area of 2ga. or so

That will work great. Also determine if your woofer moves forward or backward when the positive signal is conected to the red (or black) posts, so you know how to orient the output leads from the crossover to ypur woofer inputs.

Russellc

 

[Rex Everything]

That will work great. Also determine if your woofer moves forward or backward when the positive signal is conected to the red (or black) posts, so you know how to orient the output leads from the crossover to ypur woofer inputs.

Russellc

Thanks for the reminder on this RussellC :thmbsp:

 

[Zilch]

I'm ready to learn some. Just let me know what I need to do.

I don't want to send you on a wild-goose chase looking for the T/S parameters for those woofers. Nobody seems to know their model number, even.

Let's wait a bit and see if anyone steps forward with some information. Otherwise, we're gonna learn how to measure box tuning. Read this thread for some perspective on what's involved with that:

http://audiokarma.org/forums/showthread.php?t=144047

 

[Rex Everything]

I don't want to send you on a wild-goose chase looking for the T/S parameters for those woofers. Nobody seems to know their model number, even.

Let's wait a bit and see if anyone steps forward with some information. Otherwise, we're gonna learn how to measure box tuning. Read this thread for some perspective on what's involved with that:

http://audiokarma.org/forums/showthread.php?t=144047

It was my understanding looking for this model woofer two years ago that it really does not have a model number. I think I posted here, LH and the Altec board and that was the general consensus.

I'll take a look around again and I'll read the link you sent.

 

[Rex Everything]

It looks like this woofer was never sold as a seperate component. It's model number is 50-03-034633-01. It looks like it was also used in the 9842 studio moitors and some of the Model 15's.

Not sure if this will help or not.

Edit: This is probably not any help either but the original part number is RCA34633. I'm not finding any info though.

 

[publius]

since the jbl le14h-3 woofer appears to be a good candidate for matching to the econowave, i've got a quick question about it's distortion.

in this measurement (which has been posted on the lansing heritage forum :thmbsp, there is a concerning rise in distortion in the midrange. i have placed a red circle to identify it. while it is down about 45db from the fundamental, in this measurement the fundamental is at only 90db.

there is also a large rise in the fundamental at about 1800hz. i have circled that one too. since the distortion is occuring at 600hz and follows the same shape, i assume that this is some sort of 3rd harmonic (?) effect caused by whatever is causing the rise in the fundamental.

first question: what is the likely cause of the rise in the fundamental response and what is causing this distortion? is it a resonance in the cone itself?

second question: by using a low pass crossover to beat down the fundamental by about 10db at 1800hz, will this also reduce the 3rd harmonic distortion by about 10db at 600hz? or, will the distortion at 600hz exist regardless of how the 1800hz peak is dealt with?

 

[Zilch]

I don't understand distortion measurements, basically, but, in any case:

1) At -45 dB, it's gonna be all but imperceptible.

2) Geddes says distortion doesn't matter, and pays no attention to it.

3) The lowpass is going to bury the peak; JBL crosses LE14H-3 at 800 Hz, typical.

4) The same peak appears in all of the LE14s, as I recall.

5) See LE14H-4, the same driver with less Aquaplas damping; the distortion picture changes.

 

[dnewma04]

I don't understand distortion measurements, basically, but, in any case:

1) At -45 dB, it's gonna be all but imperceptible.

Most likely.

2) Geddes says distortion doesn't matter, and pays no attention to it.

Actually, this isn't quite what he says. He says that an all encompassing number like "THD" doesn't matter.

4) The same peak appears in all of the LE14s, as I recall.

1800hz corresponds to a wavelength of about 7.5", I wonder if there is some corellation to the drivers diameter here?

 

[publius]

I don't understand distortion measurements, basically, but, in any case:
1) At -45 dB, it's gonna be all but imperceptible.

agree. however, i think odd harmonic distortions increase rapidly with spl.

2) Geddes says distortion doesn't matter, and pays no attention to it.

geddes can only be described as enigmatic. he poo poos the import of distortion and suggests that drivers are commodity items. but, then he chooses a top of the line $300 woofer for his designs and mentions on his website that "there is a difference" between drivers.

jbl seems to focus quite a bit on distortion and has also done quite a bit of research on matching measurements to subjective listening evaluations. i suppose i go look over there to see if they have an answer.

3) The lowpass is going to bury the peak; JBL crosses LE14H-3 at 800 Hz, typical.

yeah. looks like the array 1400 employs a 4th order at 750hz, so the peak at 1800 hz is going to be down significantly.

anyway, i was just curious to know if by beating down the peak in the frequency response at 1800hz, the distortion at 600hz would be similarly reduced.

 

[dnewma04]

geddes can only be described as enigmatic. he poo poos the import of distortion and suggests that drivers are commodity items. but, then he chooses a top of the line $300 woofer for his designs and mentions on his website that "there is a difference" between drivers.

Again, he dismisses things like THD because he has shown there isn't a correlation between THD and perceived sound quality. It's just not a valuable specification. Knowing the distortion components can help us predict whether or not something will be perceived to be good or bad sounding to a statistically significant degree.

The Gedlee metric is just a further refinement of past metrics that have shown similar results in sound perception.

 

[publius]

it appears the b&c tbx100 that geddes uses in his 12" speaker is expensive for at least two reasons: 1. it has a demodulating ring, 2. it has a double silicone spider
http://www.bcspeakers.com/PDF/Design.pdf

both these features are incorporated for the purpose of reducing distortion.

here is a dummies guide to demodulating rings:
http://www.eighteensound.com/staticContent/technologies/products/18_Sound_DDR.pdf

the tbx100 is _not_ a good idea for econowavers who don't plan to use subwoofers. it rolls off too quickly (-3db point is up around 90-100hz or so).

 

[Zilch]

agree. however, i think odd harmonic distortions increase rapidly with spl.

 

[dnewma04]

Publius,

All e-wavers can benefit from subs if performance is the highest priority. Also, the 15TBX100 in a 3 cu ft enclosure tuned to 35 hz will give an F3 of ~38hz. Probably deep enough to satisfy some AKers. A lot of the speakers we are using in this thread would have an F3 in the 65-90hz range if stuffed in a maximally flat sealed cabinet.