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jwc

Dual 15 inch Corner Bass Bin - Cornscala dbb

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On 8/24/2005 6:33:18 PM jwcullison wrote:

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On 8/24/2005 8:18:06 AM DrWho wrote:

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On 8/23/2005 10:49:12 PM BEC wrote:

JC,

Could be that your amp is just not putting out the stuff below 20 hz or so perhaps on purpose. No way to hear it, just moves the cone around a lot. I also don't detect much cone movement with your Usher song and that bass is really there. It is only the stuff you can hear that counts anyway.

Bob

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That's what I was going to say too...a lot of pro amps have a 30Hz rumble filter on them cuz mics on stage and all that can easily pickup 10Hz tones which are inaudible, but destroy amps and speakers. There should be a switch on the back of your amp (or a series of switches that look like a circuit breaker) that should be labelled for turning this feature off. There's plenty of sub 30Hz material on those songs that you're missing, which your dual woofers should have no problem replicating.

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I hear what you guys are saying. This might be true. This Carver amp was made in the early 80's. I just have it for testing. It has no feature you are mentioning.

For clarification, the woofers are thumping with a great sound. I believe you guys are probably right and that I will get more low end from a better amp. Will make the switch and do the testing agin.

I will also get gaskets for the 511's and also put a baffle on the 511's to get the appples to apples.

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James, nice to know that you will break-down and use the "good Sh$!" for testing! 9.gif

Terry

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OK. DiD the deal. Terry...I pulled out the Good "stuff". All Analog. MX119, MC252, Cornscala dbb's, CD player and computer.

Yes, the overall experience was a better sound.

Bob and Dr. Who: If I play the Abracadabra track, I still get no cone movement. The bass is there. The other track with the "5hz", is better/lower than before....no cone movement. If I play the Usher track....really sounding nice...serious sound of low bass. This is definately better with the MC252. I think I will keep them this way.

STILL....NO CONE MOVEMENT. What does this mean? Anyone? Guys...the bass is outstanding. "Sounds" like cornwall bass but more of it. If I turn it up any louder, I would have to leave the room.

Bob: Played your "midrange" track several times again. The same results. 511b wins with the exception of the sax.

HOWEVER:

Played some of the tracks played last nite (I know; bad taste). Some reason the 511b is starting to become more favorable. Still the K401 is more "open and forward". 511 more "full bodied". Started to notice the 401 not as natural.

Need the gaskets, baffle on 511, and more listening.

jc

Cornscala-dbb.jpg

post-16499-13819267196356_thumb.jpg

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JC,

I gotta think about this some more. I don't have an amp that won't produce outrageous cone movements on my Cornscalas, Cornwalls, and Chorus I, playing Abacradabra.

I thought of another recording that you might want to try on your midrange horn comparison. This thing is from the 40s or 50s, with no annoying highs or lows to get in the way. Gives you a mono recording of a female voice on both channels.

http://www.bandksound.com/dsbb.mp3

Bob Crites

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Mono from each speaker would be great. Will give this a spin tomorrow.

Is having two woofers keeping them from being "challenged"? Answer not needed but a wonder to me.

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JC,

Still mulling all that over. Just a thought though, wouldn't you have essentially the same thing I am listening to if you only used one section of your double woofer as a test for this cone movement deal?

Bob

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Terry -- I just read your email to me about the driver offer. Now, that should tell you how horribly behind I am over here.

JC -- ready to try something interesting? It looks like you're using the JBL tweeters? Start by getting the K-401's back in there. Add a .90mH inductor between 13uF and tap 5. Now, change the tweeter filter to the AA type, but change the second cap in the schematic to a 4uF, and the inductor to .15mH. Connect the 4uF cap to tap 5 on the second autoformer, and then run a wire from tap 4 to tweeter positive on the terminal strip, and a wire from tap 0 to tweeter negative. Strap a 20 ohm resistor between taps 0 and 5.

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Yes..exactly. I could unhook one. Then I would need to change the taps to the ones like a Cornwall/Cornscala.

After that last post. I though of something. It could very well be my computer sound card! Maybe it won't produce frequecies that low.

May have to burn the file onto a disc.

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On 8/24/2005 10:57:42 PM DeanG wrote:

Terry -- I just read your email to me about the driver offer. Now, that should tell you how horribly behind I am over here.

JC -- ready to try something
interesting
? It looks like you're using the JBL tweeters? Start by getting the K-401's back in there. Add a .90mH inductor between 13uF and tap 5. Now, change the tweeter filter to the AA type, but change the second cap in the schematic to a 4uF, and the inductor to .15mH. Connect the 4uF cap to tap 5 on the second autoformer, and then run a wire from tap 4 to tweeter positive on the terminal strip, and a wire from tap 0 to tweeter negative. Strap a 20 ohm resistor between taps 0 and 5.

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Dean, whew. I'll need to read that more slowly in the am. I think I follow it. Would love to try it....as almost anything. What are you trying to accomplish? Does this have to do with the JBL rated at 105 dB?

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are you guys both using these actual mp3s for the tests or do you have the original source material at home? I have read that certain mp3 compressions have a high pass filter built into the compression...just wondering if it's the source material is all.

btw, you can always download NCH Tone Generator (do a search on download.com) and play test tones...then you'll get to see if your sound card digs low and all that. I know my audigy 1, 2, and Live 5.1 can all play down to 10Hz or so (though it's hard to say if it's the speaker or the sound card that's distorting the signal, but who cares when it's that low).

Btw, with two drivers you are going to experience 1/4 the cone excursion for the same dial setting on your amp (aka, it's 6dB louder for the same excursion levels, or 1/2 the excursion for the same SPL). So if BEC (was he the one recommending it?) measures how loud he's playing, you should get similar cone movement with 3-6dB more. Btw, an amp with a low damping factor won't control the cone movement very well, which might be the reason that he's experiencing so much movement with such a low note, whereas your amp might have a higher damping factor and is in more control.

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Do a search on "That Damping Factor" and you will find a post of Gil's with PWK's thoughts on the subject.

Bob

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Doc,

That is a good suggestion. I have more than one sound card laying around. I don't have an Audigy though. My best option for use is the Soundblaster Live. Will try the test tones.

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On 8/25/2005 10:21:59 PM BEC wrote:

Do a search on "That Damping Factor" and you will find a post of Gil's with PWK's thoughts on that subject.

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Hmmm, what I got out of that article is that horn loading the speaker is a good way to naturally increase the damping factor...he even states 2/3 of the way down on page 2 that the "dependance is on amplifier damping" for a direct-radiator system. I also think his minimum damping factor of 10 is a bit on the low side and I have read from other credible sources that a DF over 100 is the point of diminishing returns. I find it ironic that he tries to dismiss the DF in favor of the amplifier's internal impedance when in fact they are both directly correlated (he even provides us with the formula). To me, it sounds like trying to argue the differences between weight and mass (both of which are easily correlated between each other). Btw, there is more to a loudspeaker than its straight up frequency response, so perhaps some of the differences are buried into other areas (like cone acceleration or even certain distortions). I do agree with what I feel might be PWK's sentiment, which is to not obsess over the damping factor as there are other more important things to think about.

Nevertheless, I can't think of any other reason why one person's woofers hardly move when another's are moving all crazy style. Btw, what kind of amp are you using BEC? (I seriously have no clue). Do you get the same effect when using other amps too?

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Doc,

I have lots of amps but am not one to obsess over amps. I think it is hard to find a bad one with certain caveats, mostly being that they have enough power and reserve to give me around 50 db above the noise floor of the noisy shop I usually listen in and that they are extremely quiet. I have tube amps including a set of Quad II monoblocks and some old Scott and Pilot stuff. Nothing seems to beat my old Sony STR DE335 though and that is what I listen to most. I most often drive it with a Mac G5.

Bob

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ya, im not one to obsess over them either...still curious as to the reason for the big differences though 2.gif

I'll have to go home and try it out on me chorus II's (should be same/similar excursion considering they're both 15" drivers tuned similarily).

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Still have to listen to more of the test tones. For now I have settled on the 511b's. I really can't hear the BIG difference others have quoted. 511b not as forward. I could always switch back later.

Here are the 3/4 mounting strips for the baffle.

post-16499-13819269446098_thumb.jpg

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Here is one baffle. Neat trick!. The JBL 2404 cut out is the exact same size as a CD. Now will just need to sand a little and add the final coats of paint. I will paint the baffle too. I used a 3/4 inch riser mounted to the bottom of the top section.

post-16499-13819269446708_thumb.jpg

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The baffle for the JBL needs to be set back. If you put a grill on the front of that, the "baby cheeks" will be pressing against and pushing the grill cloth out. :( Were you maybe going to build a frame, and then mount it to the front? If so, don't forget about the JBL sticking out further than the squawker.

Looks nice JC.

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Yes Dean. Both the JBL and the 511 stick out. I will build a frame to make a grill. The baffle right now is almost 5 inches from the front "lip" of the top section. The grill "frame" to be built will be somewhat of a "box". Very similar to Seadog's 511b installantion he posted recently.

jc

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Dean...man...another train. hmmm

Here is the first look w/o hookup

post-16499-13819269574918_thumb.jpg

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Both horns rope caulked and installed. They sound fantastic. Had Krall running through them loud today.

Just need to make top and bottom grills for both. I may come up with a custom label as well. I have the Klipsch logo sitting in there just to see how one would look.

Note: These are not Klipsch speakers. Not trying to steal any registered trademarks...right Amy?

post-16499-13819269576618_thumb.jpg

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