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Crossover Roadshow


Deang

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All so these are from Al, not Dean. My screws such they have stain build up in the head of the screw, any recommendation on replacement, they appear to be number 10 about 1 1/2" long. I may switch some stuff around this weekend as I will be hooking up my Scott 222 to these for a test run.

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The crossover that Al built is or the Cornwall, not the CornScala. What's the difference? The Cornwall uses a 600Hz horn and stock drivers. The CornScala uses a 400Hz horn and about 300 different drivers. Al offers a different crossover for the CornScala, which is has the different crossover point.

Now, there's nothing saying that you can't use that crossover with a CornScala, but if you aren't using a stock midrange driver, then yeah, it's going to be screaming at you -- which of course is the purpose of the adjustable midrange -- which Al probably sent out 6dB down (red input wire on -0 and black output wire on 6). If it's too hot, just fix it!

Did he send the manual out with the crossover which explains how the autoformer and wiring scheme works -- it's not the same as it used to be.

Ok, I understand that Dean said that these are for the Cornwall only and not Cornscalas. I just want to understand why... he just wanted peoples comments on Cornwall installations and not the many Cornscala configurations? Unless these have been changed somehow they would be perfectly compatible with Cornscalas and I am current using them as such.

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Would it be too much to ask, when reviewing these crossover to list the horns and drivers being used, as some may not be suited for the crossovers being used.

For instance I see a lot of Cornscala's out there that have the Selenium D-405 driver coupled to the JBL 2380 clone horn. This combo is not compatible with a 6k crossover because the D-405 start to roll off around 4K, and it has a rated SPL of 111. This is going to use a bit more attenuation than the K-55, and requires a different crossover point. For this combination, ALK offers a 400hz-4khz crossover option.

SPECIFICATIONS

Nominal impedance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 W

Minimum impedance @ 3,450 Hz . . . . . . . . . . . . . . . . . . . . . 6.3 W

Power handling

Musical Program (w/ xover 800 Hz 12 dB / oct)1 . . . . 200 W

Musical Program (w/ xover 1,200 Hz 12 dB / oct)1. . . 250 W

Sensitivity

On horn, 2.83V@1m, on axis2. . . . . . . . . . . . . . . . . . . 111 dB SPL

On plane-wave tube, 0.0894V3 . . . . . . . . . . . . . . . . . . 113 dB SPL

Frequency response @ -10 dB . . . . . . . . . . . . . . 400 to 20,000 Hz

Throat diameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 (2) mm (in)

Diaphragm material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Titanium

Voice coil diameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 (4) mm (in)

Re . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.8 W

Flux density . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.70 T

Minimum recommended crossover (12 dB / oct). . . . . . . . . 800 Hz

Dave

Dave,

I don't know of any Cornscalas that have been with the D405TI driver you have posted the specs for. Several hundred have been built with the phenolic diaphragm version.

Bob Crites

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Al also has a network with a 4000Hz crossover point that serves no purpose. I think he's trying to toss something out there to compete with Bob's A/4500, but missed by 500Hz. Uhg, I love Al, but I've got my own business to run, so I'm not going to be supporting and promoting his products any longer, especially when I've got products and solutions that work just as well or better.

I'm pretty Bob uses a 500/5000 for the Selenium D405 (phenolic version).

If there is a problem or issue with the Cornwall version of the Roadshow Crossover, please contact Al.

If you're having a CornScala issue, which as far as I'm concerned, is a product built and sold by Bob, then please contact Bob.

Seriously, I just don't have time to deal with it all, I barely have time to deal with mail that relates to my own stuff.

DIY efforts should have their own threads, and if they're "CornScala" type builds, as much information as possible should be provided. There are plenty here who are willing to help, including me if I have the time.

I will take on work fixing "issues" for a fee, but for the reasons stated on my site, I don't support DIY efforts. It also doesn't pay well, and if the person doesn't get the expected result or screws something up -- guess who gets to deal with it?

Now back to Carl (who won't yell at me). The network looks old and dilapidated. so I'm worried about the condition of the autoformer. The mids shouldn't be as hot as they are. I think there is something wrong when a CornScala has to be tapped out like a Heresy to sound right. I think you said you had some B2s? I would like for you to drop them in and report back.

Edited by DeanG
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Guest David H
I don't know of any Cornscalas that have been with the D405TI driver you have posted the specs for. Several hundred have been built with the phenolic diaphragm version.

Even worse than that, I posted the specs for the 408ti.

With or without specs the statement is still valid. A 400-6k crossover is not suitable for use with a D-405.

Dave

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Guest David H
Al also has a network with a 4000Hz crossover point that serves no purpose. I think he's trying to toss something out there to compete with Bob's A/4500, but missed by 500Hz.

Why does a 1st order crossover at 4500hz have purpose and a 2nd/3rd order crossover at 4000hz not have a purpose?

I thought the idea of offering several network choices was a good idea, - more driver / horn combinations. Especially popular with the DIY community.

Dave

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Now back to Carl (who won't yell at me). The network looks old and dilapidated. so I'm worried about the condition of the autoformer. The mids shouldn't be as hot as they are. I think there is something wrong when a CornScala has to be tapped out like a Heresy to sound right. I think you said you had some B2s? I would like for you to drop them in and report back.

Will do. The B2's look only marginally better but I only saw them once, briefly. Anything need to be changed on them or just slap them in?

The networks look old and dilapidated to me too. That's one of the reasons I wanted to send them in but it was certainly easy enough for me to try the things you suggested. I appreciate all the help.

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Where did I ever say a first order filter with a 4.5kHz had a purpose?

Notice #6 of his FAQ section. The question is: "Should I move my squawker / tweeter crossover down to 4000 Hz?" He then quotes me where I present my argument against moving it to 4500Hz.

It was my idea to offer up the various tight budget oriented Universals. A 4000Hz version wasn't not one of them, but a 4500Hz version was -- to accommodate those who really wanted one.

Edited by DeanG
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Carl, just drop them in, no changes should be required. I didn't suggest this initially because I thought you were using them in another set of loudspeakers -- fixing the AAs made more sense.

6dB down for the mids should be correct, something's wrong.

@Dave -- are we 100% sure about the gain with your horn?

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Where did I ever say a first order filter with a 4.5kHz had a purpose?

Ouch ok.

Dave

Hmmm, that didn't come out right -- I mostly just meant I never said it. I totally get what Bob is doing with that, just because I don't care for it doesn't mean it doesn't have any validity.

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Dave -- are we 100% sure about the gain with your horn?

I am not 100% sure of anything. But, I might be willing to wager on it?

Dave.

I wonder if this is a K-55-V vs K-55-M thing. 1.5 to 2dB doesn't sound like a lot, but 2dB is almost 3dB, and that kind of difference might justify a drop down to tap 2.

post-1106-0-24200000-1392684042_thumb.jp

Edited by DeanG
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Guest David H
Dave -- are we 100% sure about the gain with your horn?

I am not 100% sure of anything. But, I might be willing to wager on it?

Dave.

I wonder if this is a K-55-V vs K-55-M thing. 1.5 to 2dB doesn't sound like a lot, but 2dB is almost 3dB, and that kind of difference might justify a drop down to tap 2.

That sounds reasonable enough, however it would have been exceedingly hot with the M driver and the K-400.

Dave

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Carl, just drop them in, no changes should be required. I didn't suggest this initially because I thought you were using them in another set of loudspeakers -- fixing the AAs made more sense.

6dB down for the mids should be correct, something's wrong.

@Dave -- are we 100% sure about the gain with your horn?

I should be able to do a little tinkering on Wed. I'll report back.

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OK, it's a mixed bag. I installed the B2's and immediately noticed that the mids weren't making my ears bleed any more. I only did one speaker for now however. So far so good. After about 5 minutes though, the sound started fading in and out occasionally. Could this be a symptom of a bad crossover? I've never experienced this phenomenon before. I've double checked all connections inside and out.

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