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PostPosted: January 9th, 2018, 7:33 pm 
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Any specific recommends for the RTA - I have an iPhone.

I am using the Model 15 (series 1) crossovers. I'd found the Model 15 schematic in an older Lansing Heritage Forum thread
and noticed the woofer runs full range! Its directly connected to the input lugs. The JBL 2214 woofer is 8 ohm, the 908-8A driver I got via AK is also rated 8 ohms


J-ROB wrote:
If you don't have a standalone RTA setup, get an RTA app for your phone and see where you are.

Are you using the M15 xover? No filter on the woofer in the M15, I think, so the woof impedance doesn't really matter, but the 902 should be 8 ohms.

I think the M15 xover has a MF notch and an HF control which changes the peaking network but it is not a volume pad, per se.

Properly balanced, that bent horn will be a bit on the smooth and laid back side, which is a good thing about it. It is definitely not an in-yo-face sort of horn.


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PostPosted: January 9th, 2018, 9:00 pm 
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I googled and found Octave RTAin the iTunes store - nice spectrum display - looks pretty good.
Did the download and I'll check it further tomorrow ...

(Thanks for the suggestion!)


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PostPosted: January 9th, 2018, 9:03 pm 
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Yeah, Octave RTA is what I use. Very handy indeed.

Try it at a live concert and see how little HF you're getting! The 32C is just about right in that respect.

I like that scheme of running the LF full range. Of course, the response of the LF driver will then suggest an appropriate crossover point. 414s play up to 6k+ pretty well, for example giving a lot of flexibility and requiring a low pass network if you want to run the horn low.

I had good results with a high first order crossover on 802s and a 32 filling in above the 414s.

I don't know anything about that JBL woofer. Figure out how high it plays on its own, a very useful data point.


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PostPosted: January 9th, 2018, 10:35 pm 
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J-ROB wrote:
Yeah, Octave RTA is what I use. Very handy indeed.

Try it at a live concert and see how little HF you're getting! The 32C is just about right in that respect.

I like that scheme of running the LF full range. Of course, the response of the LF driver will then suggest an appropriate crossover point. 414s play up to 6k+ pretty well, for example giving a lot of flexibility and requiring a low pass network if you want to run the horn low.

I had good results with a high first order crossover on 802s and a 32 filling in above the 414s.

I don't know anything about that JBL woofer. Figure out how high it plays on its own, a very useful data point.


When I get some time I'll play some wide spectrum music (Earth, Wind, & Fire perhaps)
and get a sense of how the speakers play

Poking around the Lansing site I found these specs for that 2214 Woofer:

"Here's the 2214H's T/S parameters (L100T), etc, and the 128H-1 used on the 4412(A)"
|.. .. ...| 2214H | 128H | units . .|
| fs .... | 23 . .| 20 . | Hz . . . |
| Qts ..| .24 . | .24 .| . . . . .|
| Qms .| 10.5 .| 7.0 .| . . . . .|
| Qes .| .25 . | .25 .| . . . . .|
| Vas ..| 7.9 . | 9.9 .| ft^3 . . |
| Eff .. | 1.1 . | .86 .| % . . . .|
| Pe .. | 200 . | 100 .| watts . .|
| Xmax | .26 . | .31 .| inch . . |
| VD .. | 21 . .| 25 . | in^3 . . |
| Re .. | 5.6 . | 5.7 .| ohms . . |
| Le ... | 1.3 . | 0.6 .| mH . . . |
| SD .. | 81.7 .| 81.7 | in^2 . . |
| Dia ..| 10.2 .| 10.2 | in . . . |
| Bl .. | 16.0 .| 16.0 | Newt/Amp |
| Mms .| 90 . .| 70 . | grams . .|
| flux .. | 1.07__| 1.07 | tesla____|


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PostPosted: January 10th, 2018, 12:11 am 
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Download a white noise MP3 and play that for your RTA.

If you disconnect the horn, you will see what the woofer can do.

With horn and woof hooked up, you can get an idea of how everything matches up.


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PostPosted: January 10th, 2018, 8:11 am 
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J-ROB wrote:
Download a white noise MP3 and play that for your RTA.
If you disconnect the horn, you will see what the woofer can do.
With horn and woof hooked up, you can get an idea of how everything matches up.


Gotcha - I have a Chesky demo CD with Pink and white nose tracks on it -
I'll have to dig it up when I get home this evening.
Thanks!


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PostPosted: January 10th, 2018, 8:27 am 
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Forsooth, Chesky audiophile white noise is much better than generic mid-fi white noise.

You can learn a lot from that $5 app and some good noise.


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PostPosted: January 10th, 2018, 8:36 am 
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Location: Parkville, Maryland
hjames wrote:
J-ROB wrote:
Download a white noise MP3 and play that for your RTA.
If you disconnect the horn, you will see what the woofer can do.
With horn and woof hooked up, you can get an idea of how everything matches up.


Gotcha - I have a Chesky demo CD with Pink and white nose tracks on it -
I'll have to dig it up when I get home this evening.
Thanks!



Actually that's not correct. You measure with Pink Noise -- It is random noise having equal energy per octave, and so having more low-frequency components than white noise.

The typical diet for a RTA is pink noise.

_________________
Walt


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PostPosted: January 10th, 2018, 8:39 am 
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Walt is absolutely correct. Forgive me.

I shouldn't even be awake at 7AM, let alone posting, but I have to pick somebody up at the airport.


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PostPosted: January 10th, 2018, 8:46 am 
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Thanks to both of you! Sad thing is I am busy with this "Job" thing when I want to do testing and chart some of this stuff out! Ah well, Saturday is coming ...

Again, thanks for the ideas and help as I start this project!


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