Cornwall with WAF appeal (WaCorn)

[jwc]

By all means, I bet it is too low. I think the port length should be about 5".

I'm not sure I understand your example of using the speaker as a microphone. Be more specific.

I have done what Al suggested measuring a port and the driver independently upclose. That left side of the curve is different. There is no peaking a 35Hz then a dive again at 40-50Hz and then peak again at 60Hz.

I'm not taking the speaker outside. However, I may think of how I can do that tilt thing.T

Tell me more about hooking the speaker in "parallel"

[Marvel]

jwc,

He's talking about running a line back from the speaker terminals, into a LINE input on your sound card, and measuring the response. the loading a response of the speaker system will affect the response you can display.

It can't be a mic. inout as the signal level will be too high. A line level should indeed provide very little current flow into the sound card and not damage it. Plus, you shouldn't have to play back at a very high level at all. It works the same way that putting a DMM across something. The meter input is a very high impedance so the circuit pretty much doesn't see the meter.

Bruce

[Al Klappenberger]

jc,

I have the formula for combinging the two plots witn a single port, but I will have to do some research when a dual port is involved. Post the plots anyhow. They will tell a lot of other good things anyhow!

Al K.

[jwc]

The woofer upclose with ESN, dual 4" ports 10" length

[jwc]

The one port upclose with ESN, dual 4" ports 10" length

[BS Button]

Crap, you're pullin away. I'm in your dust. Remember that movie. "I'm gonna getcha sucka"

[jwc]

Ok here. same test with 7" ports

Here is one port only

[jwc]

here is the woofer only with 7" ports

[jwc]

Ok guys. Here is the RTA of the Bass Bin currently with the 7" ports from the listening position. Looking better. Ran 7 times and this is the average.

[jwc]

Now we are talkin. Look at all the drivers with the bass bin with 7" ports

[jwc]

I've been listening to them for about 45 minutes. Placed them next to the dbb's. You can see now that they don't look as tall as you may have thought. The dbb's are the height of a Khorn.

The TallCorns will sit in a position just like this at the lakehouse. They are just over one foot from the back wall.

It is noticeable that these cabinets are tuned lower. I am embarrased to say that I have heard sounds I haven't heard before on some of my standard test music. I'm not sure if it is a result of Bob's Tweeter or that ESN.

The Tallcorn is balanced. I'm sure it will have a little less crispness when I put the Grills on there. They sound great. It may be time to paint which I dread.

I must say that the RTA on this project was a big help. Whether or not the speakers are balanced in general or just balanced to my room...not sure. I hope I didn't bore too much with the graphs. I still can change the ports at anytime if someone wants to contimue with the suggestions.

I am yet again impressed. My initial opinion is that these are sounding better than my Cornscalas but not the dbb's. The TallCorns do go lower with the bass. They again can go VERY loud and be tolerable at the same time.

jc

[BEC]

jc,

When are you going to start the Cullison Speaker Company? Looks like you are getting the speaker line-up covered pretty good.

Bob

[Marvel]

Very nice looking. Are you going to have these painted (thought you had mentioned that) or do some sort of stain on them?

Bruce

[jwc]

Funny you mentioned the stain idea. I just now had asked my wife about veneer or stain am I got a firm "Hell No". They will be jet Black painted. Grills Duracrest #17 Black.

Yes the Cullison Speaker Company. Grand idea. It is already in business. I sell products to myself. I wish I could make a livin doing this.

jc

[jwc]

Bob. Do you remember from my past dbb thread in which you were sending me links to test audio sound files in order to "see" the excursion of the K33 in my dbb's? You know, to this date, I have never seen them move. I mean really, the room is full of great bass and you can put your eyes up to them and they aren't moving.

Now with this new woofer of yours, that isn't the case. Yes the woofer is "moving" when turned up to a high volume (too high for my casual listening). What do you think about this. Is the due to the high efficiency of the dbb's (probably slightly more than the Khorns) or just the fact I've got two woofers on the dbb's requiring "less work"?

jc

[BEC]

I would say you are working the single woofer harder. Also I think the CW1526 may move more at the lower frequencies since it can reproduce more of them.

Bob

[DrWho]

And because the CT digs lower it probably has a steeper Q on the cutoff...which means the woofer is unloading faster.

You might consider going back to the 10" ports and throwing in a

peaking-2nd-order highpass filter...it'll only increase cone excursion

in the range of the tuning point (where the cone is barely moving at

all) and then it will protect the driver from signals below the tuning

point. You can model it in winISD to get an idea of what I'm talking

about.

[Al Klappenberger]

Jc,

What procedure did you use to tune the port? I see plots for different length ports. You need to actually tune the port correctly before you bother doing any plots.

AL K.

[jwc]

Al, my decision on ports lengths were all estimated first in WinISD. I was shooting for a cabinet tuned to about 39Hz. When plotting this with BOB's woofer in a 6.5 cu ft cabinet, the dual 4 inch port lengths would be about 4-6 inches.

Now I started out longer just for the heck of it. The 10" plot was looking like some estimated on WinISD when the length was too long....in other words....starting to roll off slowly under 80-90Hz. The plot would never roll off quickly on the low end and just continue on onto the very low frequencies.

The Cornwall basically will peak bigtime between 50-80Hz and drop off fast.

Other than that, I have done the above posts. I would appreciate further help to perfect the tuning. So maybe I am not doing the basic work to "tune the ports". Tell me how.

Doc Who. You think the low frequecies will be harmfull to my woofer. Not sure how that peak bandpass will integrate with Al's design. I would rather have the woofer just roll off very quickly on the low end. I still think the port could be shortened a little bit. I must say that it sounded pretty good the way it is right now at 7".

[DrWho]

Doc Who. You think the low frequecies

will be harmfull to my woofer. Not sure how that peak bandpass

will integrate with Al's design. I would rather have the woofer

just roll off very quickly on the low end. I still think the port

could be shortened a little bit. I must say that it sounded

pretty good the way it is right now at 7".

The filter would have to be an active one...as in go before the

amplifier - so it wouldn't affect Al's passive network. I do not think

you will damage the woofer at all - just that any cone movement =

distortion.

But if it sounds good then hands off! Shut up and enjoy the music []

Now if you want to play around with it I'm all for experimentation. You

should have quite a few different lengths of port by now shouldn't you?

Just for kicks you should try porting too high (like use a 4" length

leftover).

One thing you really need to be doing is testing the system at

different SPL's (which is another reason outdoor testing is a good

thing...). We've talked about the cornwall being ported too high in the

past and though that might be true for the "low-signal behavior", I bet

the higher port tuning becomes beneficial with the "large-signal

behavior" - all that to say, try measuring at ear bleed volumes, just

to get an idea of what direction the system starts to lean.

Btw, try doing some of your measurements, but with the mic on the

floor...there shouldn't be much directivity at those lower frequencies

so don't worry about tilting the speaker forward. I'm thinking it might

get rid of some of those steep dips in the response.