Speakerfritz Left me thinking about something ?

[dtel]

Help me understand something, if the LaScala LF crossover is at 400hz does that mean that the K400 only plays down to 400 then the bass driver plays below 400 ?

No overlap like when you match a sub to a main speaker ? Or is it the crossover that separates the signal at a certain frequency and directs only certain frequencies to each specific driver ? That's how I thought it worked.

Sorry to ask, which to some is a silly question, just trying to figure out another problem.

I am playing around with the idea of mwm bass bins and wanted to put a LaScala K400 mid and tweeter on a single bass bin, for the workshop and outside.

All I could find the was the crossover on the LaScala ll for LF is 400, and from the commercial page the mwm when used in the mcm configuration cuts off the Lf also at 400.

My confusion in this is the mcm uses a mid bass, and I was wondering if that's why Speakerfritz said just use a LaScala. I don't have LaScalas, and had the crazy idea to just take the part I liked from the LaScala and give it a little more bass since I have the mwm bass bins already.

Was hoping to use a A or AA crosover, but is the different bass bin configuration of the LaScala to mwm bass bin going to throw it off compleatly, and sound terrible ?

Remember it's not for critical listening for sure, while working in the shop or outside.

It sounded so easy when i first thought of it, I just never tried to put anything not matched together like this.

[wuzzzer]

There will always be some overlap. How low a K400 driver will play depends on how many decibels per octave that the crossover is designed to be down.

[mas]

Here is a diagram of an idealized crossover region. But hopefully it will help you to visualize the crossover function more easily.

The overlapping slopes ('orders' which equal 6 dB/octave each) which 'decrease' in magnitude relative to a specified crossover 'corner' freq oriented about a specifiec crossover frequency according to design create a region where the two regions sum to a flat magnitude.

What is not illustrated is the phase response which will only cooperate and allow for a simple summing if the two signals are in phase (aligned in the time domain).

...Hope that helps a bit...

[Guest " "]

In the MCM Grand 3 the MCM bass bin covers 40 - 300 hz.

In the MCM Gran 4 the MCM bass bin also covers 40 - 300 hz

I don't think you will be happy with a k-400 on top of an MWM bass bin. I'm thinking you will have a mid bass hole. For the MWM there is a 10 inch mid bass driver that covers this hole.

In a 3way senerio the MCM system uses 300hz, 800hz xover points.

In a 4way senerio the MCM uses 300hz, 800hz, and 4k xover points.

So if you were to stack a somthing on top of an MWM choices are to use a LaScala or Hersey to cover above 300hz. If you really look at this, a Heresy would actually work closer to the xover points of 800hz and 4khz. You would crossover the MWM at 300hz. But i think you wold like the sound of stacking a LaScala better.

[ben.]

I bet it wouldn't be too much to trouble to get a 400/700 top end to sound good in a shop on top of MWM. A dip around 300-400 Hz isn't the worst sounding thing in the world, and if it isn't too severe is actually preferred by some. It would depend on what the bass bin does in that frequency range. If it rolls off smoothly as frequency rises, it would be easy to work around. If the response gets peaky and weird, that's a different story.

The sensitivity of the bass bin can be another issue if trying to use the stock networks...

[DrWho]

If I remember correctly, the MWM is useable to 500Hz? In fact, I think the guys running the K402 on the MWM are crossing right around 450Hz without any holes in the frequency response.

I think you'll be fine crossing over to the K400 at 400Hz. Just keep in mind that the MWM won't have the same impedance, sensitivity, and frequency response as the Lascala LF. The most noticeable issue would be dealing with the sensitivity (getting the squawker and tweeter to match the volume of the MWM).

Are you going with a single MWM bottom or do you have the dualies? (how many drivers are in the cabinet?)

[Deang]

What Ben and Mike said.

Sensitivity is the main issue, those bottom sections are probably 108dB/w. You could use the Type A or AA, and slightly modify it to bring the midrange up, no big deal there. The tweeter is a different issue, since it's already being run full out -- it'll be 3dB down compared to the rest of the system. Some JBL 2404's would probably work, but kind of expensive for what you're doing. If you decide to try this let me know, I'll help you with the network -- or just ship them to me and I'll do it for you (no charge:).

[jwc]

Dean and Dtel.

I have a schematic that will work for the combination of Two K33's wired parallel XO at 400Hz with the midrange.

Yes.....designed by "you know who". Constant impedance with two autoformers to adjust for attenuation of the midrange and the tweeter. It is not an ESN but an "ALK Universal equivalent". Would only be one board and not that expensive (except for Dean's high priced labor)

Yep...tweeter sensitivity will be an issue. May want to skip a super tweeter and get a small horn and driver combo used that doesn't require EQ. I have this same plan to throw some MWM's in a shop. I was considering using this combo as the "tweeter". Inexpensive...and could still find some used. Thery are exponential and would work well for XO at 5800Hz-6000Hz...like in the schematic I was speaking of.

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=294-622
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=294-600

The MWM gets "sloppy" after 300hz with some peaks and troughs if I remember. But still awesome at two way if want to cross at 500Hz. Esp fine for the shop system.

Fun project Dtel.

jc

[dtel]

Thanks everyone for the ideas.

Oh great more choices. [:$].

DrWho It's single bins, one for each channel.

I don't have any crossovers right now for this, so I will probably look for a used pair to have modified, thanks Dean for the offer, wouldn't expect you to work for free.

All I have is a pair of single mwm bass ( 2 bins ) and a pair of Heresys in the shop with the Bob Crites tweeters. So I am trying to get this crazy idea done with out ending up with a complete set of mcms and a big expense.

I really do appreciate all the ideas to help me figure this out.

[Deang]

"I have a schematic that will work for the combination of Two K33's wired parallel XO at 400Hz with the midrange."

Is it the one from your DBB project? Did you have Al tweak it to account for the horn loading? I mean, paralleled, horn loaded K-33's isn't going to be 3 ohms, which is where I think he swamped to -- and doesn't the MWM use K-43's. Anyways, a pair of networks like that, even built on the cheap and DIY'd -- is still going to cost a couple hundred.

"...Constant impedance with two autoformers to adjust for attenuation of the midrange and the tweeter...."

Well, in this case, you don't even need an autoformer for the midrange, and if you were going to use one at all, it wouldn't be to attenuate, but to lift the output of the K-77 (wire it backwards).

"Would only be one board and not that expensive (except for Dean's high priced labor)."

Ha Ha, well, I'm not a hack and you get what you pay for.

"...May want to skip a super tweeter and get a small horn and driver combo used that doesn't require EQ... I was considering using this combo as the "tweeter"...But still awesome at two way if want to cross at 500Hz."

Uh, that driver only goes down to 1.5kHz, am I missing something here?

[jwc]

That is right. I'm referring to only using the B&C combo from 6000hz and up...as a "tweeter". 90 x 40 coverage. You would still just use K55/K400 for mids 400-6000Hz. In my case I have the original K-260 from the MCM series.

The MWM's would need to be loaded with K33 or Crites...not k43's for "it" to work.

Yes the schematic is from the dbb thread. I have measurements ("ALK type") of parallel horn loaded K33's. Still has 3 ohm "complex impedance". I don't want this to turn into an ALK thread.

So you could have autoformer for the K55 (if needed) and the B&C or other tweeter of choice...not the K77. I have no advice for back wiring an autoformer.

This is just an idea....and frankly I feel confident that it will work for your intentions. Not sure if Dtel already has K33's lying around or not. You could also "sacrifice" autoformers off a pair of vintage heritage networks and use those. It looks like I made this thread too complicated by inviting abunch of techy junk...philosophy...and so on. Sounds simple to me and not that expensive but I may have made this more frustrating for Dtel than needed. Sorry dude.

If you wanted to make it more complcated...there is some ESN for this possibility too...no delay option with passives I know. If there any nutcases out there like myself with the same interests....you can contact me personally and I can fill your head with a bunch of other useless audio dreams.

jc

[Deang]

"I'm referring to only using the B&C combo from 6000hz and up...as a "tweeter". 90 x 40 coverage. You would still just use K55/K400 for mids 400-6000Hz."

O.K., I see.

"The MWM's would need to be loaded with K33 or Crites...not k43's for "it" to work. Yes the schematic is from the dbb thread."

What are we up to now, about $1000?

I have measurements ("ALK type") of parallel horn loaded K33's. Still has 3 ohm "complex impedance".

Here are John Warren's measurements of the "4 ohm" K-33.

[jwc]

Dean, your image didn't load but I've seen it before.

I'm not an expert at measuring impedance of drivers. Please notice How I Referenced my statements such as "ALK" and "complex impedance". I've built networks based on those types of measurement techniques and they "work" for a DIY makeshift guy like myself.

$1000...what! Man I though you network expert got parts for cheap.

jc

[Deang]

Since the impedance is "complex" -- it moves around quite a bit. Some say it's "6 ohms" when horn loaded. Near the crossover point, without a coil -- it's closer to 8.

Here is the anechoic chamber plot with the coil in the network. Notice what the impedance is at the crossover point.

[jwc]

I see the image now. yes...seen it before and "chronicled" before.

Dean....are we digging up bones? I'll stop giving ideas and let you and Dtel actually complete this project. I need to get back to work anyway.

jc

[Deang]

I'm not giving you a hard time, just trying to explain why it don't work in my mind.

dtel wanted a simple fix so he could get up and running in his workshop. You suggested a new horns, drivers, networks, and four new BEC "K-33's". Ain't that about $1000.

[jwc]

So we have ruined this thread.

I didn't notice the second image. I think that was from the same thread. Now is that horn loaded and where is the XO point?

Again...the "complex impedance" measurements are by way of using a certain technique.....you know what I'm referring to. I'm certainly not making a stand of right or wrong.

So...The K33 is 8 ohms loaded........press on.....

Dtel........are you still there? I hope my insertions didn't cause frustration.

jc

[jwc]

I'm not giving you a hard time, just trying to explain why it don't work in my mind.

dtel wanted a simple fix so he could get up and running in his workshop. You suggested a new horns, drivers, networks, and four new BEC "K-33's". Ain't that about $1000.

oohhh. I was assuming he had K33's....needing only two with his setup. Thought he had the K400 and K55 already. I was suggesting one used combo B & C or some other option and just the network. I was also assuming he would run mono since he has only one stack or a bass bin that requires two K43's or K33 total. then it would be cheap.

He would either split the bass bin for stereo or used them stacked and run mono. If stereo with one woofer per "speaker", then all my suggestion are even dumber then they have come across already.

I'm not giving you a hard time, just trying to explain why it don't work in my mind.

Yes you are giving me a hard time....but I like it as nobody has done that in awhile...since I stopped all my DIY threads. A lot of it never worked in my mind either but just follow along with some of the "logic" and it has worked for me. Maybe I'm easily satified.

jc

[Deang]

Just because two people are discussing something a bit off topic and don't agree doesn't mean the thread is "ruined".

The first plot compares the free air measurement to the woofer loaded -- out of network. The second plot shows what happens when you drop the coil in -- nearing the crossover, or where it sums -- impedance is roughly 11 ohms. Big difference between 6 and 11 ohms. Al designs diplexers -- the impedance of the high pass section is matched to the impedance of the low pass section. Seems to me, that for it to work "right", the impedance of both sections needs to be roughly the same at the point of summation. So, if you don't account for the reactive element, I think you might have a problem. I can't imagine the MWM being much different. You parallel two K-33's, and the free air, horn loaded, and in-network impedance measurements will all be different. I'm thinking one might want to know the behavior with the reactive element in play before they calculate out the values. The math is the starting point, then you got to start adjusting values until it actually does what the model says it's supposed to.

[DrWho]

Ya know, Dtel is gonna need an amp to drive this system too....I would recommend a single XTi strapped mono with an active crossover to handle the transition between MWM and the K400. No need for stereo sound for the stated applications.

And to make life really easy, just drive the MF/HF section of the passive crossovers you have right now - basically treating the lascala top end as a single tweeter. The only thing you'd have to do, Dtel, is set the crossover point and then adjust the volume of the MWM accordingly. One of the guys that has the XTi should be able to walk you through it on the phone if you're having trouble.

So what, about $500? []