My turn to build JC's DBB

[Pete H]

A horn is just a rigid boundry. I doubt materials sound different. Certainly look different. I prefer the look of a beautifully crafted wood horn.

Just a question regarding materials sounding different; is the only goal for horn selection to be created with the proper dimensions and to not resonate at all, and if this is the case then is the reason that some complain about the sound of metal horns due to the fact that they weren't constructed rigid enough? It also makes me wonder about the selection of specific wood for the faces of acoustic guitars and why guitar manufacturer's wouldn't just choose the species solely based on a strength to weight ratio. Just curious.

[bigrfish]

A horn is just a rigid boundry. I doubt materials sound different. Certainly look different. I prefer the look of a beautifully crafted wood horn.

Just a question regarding materials sounding different; is the only goal for horn selection to be created with the proper dimensions and to not resonate at all, and if this is the case then is the reason that some complain about the sound of metal horns due to the fact that they weren't constructed rigid enough? It also makes me wonder about the selection of specific wood for the faces of acoustic guitars and why guitar manufacturer's wouldn't just choose the species solely based on a strength to weight ratio. Just curious.

Horns I don't know, but guitars I do. Different woods definitely produce a different sounding guitar, not only the top, but also the sides and back. There is one fundamental difference, though...in the guitar world we expect the choice of wood to be a major player in the tone of the instrument.(with the side-benefit of attractiveness) So, the question is, do we want this in a horn?? That could be studied to a degree, but for now, let us merely think about it.

A question...when a person reacts to what they consider the resonances of a metal horn, is THAT really what they are objecting to? How much of that objection might be due to prejudice, based on emotions rather than logic and empiric evidence? How much due to driver choice, characteristics of the crossover, anomalies of the room, or even poorly-recorded and mastered records.

On the grand list of squeaky wheels that need greasing, I imagine what the horn is actually made of is low down on the list, unless it does exert some negative or perceptible difference. The dimensions and geometry of the flare should be more important?

If I were picking the best possible material, I would want it to be something that I COULD NOT HEAR. One can hear the wood in a guitar, but for my stereo, I do not want it to be a creator of sound, I want it to be a reproducer .

Chuck

[Pete H]

Thanks for the response Chuck, well put! Now back to the build and testing, come on Rudy we want to hear more[]

[Rudy81]

Thanks for the response Chuck, well put! Now back to the build and testing, come on Rudy we want to hear more

Pete, much more will be forthcoming when I get things properly setup. I sat down last night to have a nice listen after performing invasive surgery on my DCX2496. I also reset the DCX to start over with all new settings. After all that, I sit down to listen and immediately realize that my right driver is out of phase again??? WTFO? I spent over an hour last week verifying that I had, what I thought to be a reversed diaphragm in one of the P. Audio drivers. It was strange since I had not noticed that issue when they were mounted on my Khrons. I put everything to 'normal' as it should be and things sounded good again. I KNOW for a fact that my right driver sounded and acted 'reversed' a few days ago. I wrote about that a few threads ago.

All I can surmize is that the DCX was somehow electronically reversing that driver without showing me the check mark in the appropriate box.

So, all is well for now....I hope.

I will not be able to listen again for several days....so further evaluation will have to wait. I want to get the cabinets set up just right before I truly evalate them.

[Marvel]

It also makes me wonder about the selection of specific wood for the faces of acoustic guitars and why guitar manufacturer's wouldn't just choose the species solely based on a strength to weight ratio. Just curious.

Pete,

Acoustic guitar tops, or 'faces' as you call them, are made from different woods for different reasons. Woods for the tops are usually called tone woods, because different species will help shape the overall tone of the instrument. Many classical guitars, with nylon strings, have tops made of cedar, sometimes spruce. Cedar is very lightweight, and along with the nylon stings, produces a softer, mellower tone.They also have tops made of spruce.

Lately, steel string guitar makers have been trying different wood for the tops, from the usual spruce (different kinds of spruce, too), mahogany, walnut, koa, redwood. All sound different.

The woods used for the backs and sides also contribute to the overall tone. Mahogany, rosewood, maple, walnut and koa are used here as well.

Bruce

[Pete H]

Thanks for the response Chuck, well put! Now back to the build and testing, come on Rudy we want to hear more

Pete, much more will be forthcoming when I get things properly setup. I sat down last night to have a nice listen after performing invasive surgery on my DCX2496. I also reset the DCX to start over with all new settings. After all that, I sit down to listen and immediately realize that my right driver is out of phase again??? WTFO? I spent over an hour last week verifying that I had, what I thought to be a reversed diaphragm in one of the P. Audio drivers. It was strange since I had not noticed that issue when they were mounted on my Khrons. I put everything to 'normal' as it should be and things sounded good again. I KNOW for a fact that my right driver sounded and acted 'reversed' a few days ago. I wrote about that a few threads ago.

All I can surmize is that the DCX was somehow electronically reversing that driver without showing me the check mark in the appropriate box.

So, all is well for now....I hope.

I will not be able to listen again for several days....so further evaluation will have to wait. I want to get the cabinets set up just right before I truly evalate them.

I know you're working on things as you have time, just picking! I've been so overwhelmed at work that I'm having to live through other peoples build threads at the moment. I keep looking at the report from Hope and thinking, I know Rudy was there, but you must have hid from the camera well.

[Rudy81]

I think we were all busy taking pictures of speakers and stuff and forgot about the people...typical guys.

[Rudy81]

Now, back to work on the listening room. Today was actually a day of mixed emotions. I said goodbye to my Khorns of 5 years. Bittersweet for sure. In retrospect, and after my listening experience at Hope, I wish I had sealed the backs and given that a chance. The Khorns at hope were something totally different in the bass department than mine.

The good thing was working on the DBB's tonight in terms of speaker placement. I spent a couple of hours tweaking the placement and toe-in of the speakers. I am thrilled with the flexibility of being able to move the cabinets around all I want. I found a particularly excellent spot about 6' in front of the wall behind the speakers and 4' in from the side walls. I do have HF absorbers at the reflection points.

The P. Audio horns and drivers continue to shine as they did when I mounted them on my Khorns. However, I have them toed-in just a little and am getting an very large soundstage with excellent detail. The image with the horns pointed outside my sitting position is excellent as well. The soundstage depth is superior to what I remember from the Khorn setup, which was about 1' in front of the wall behind the speaker and flush with the side walls in their false corners.

I listened to quite a bit of male and female vocals and the P. audio horn and driver are excellent. Smooth, realistic and detailed.

The DBB bass bins are thus far very nice. They produce a tremendous amount of bass. Audyssey has attenuated the heck out of the bass frequencies, much more than it had done on the Khorns. My next thing is going to be to set the entire system to a flat EQ on the crossover and then run Audyssey. It will set the system up for flat response with some attenuation in the very high frequencies. I will then go back and use the EQ to set the sound to my liking. I truly wish I had a way of knowing what Audyssey was doing.

The ported cabinet sound is much more of what I was looking for, although it is very different than the Khorn bass sound. The DBB does not seem to be very high in the distortion department and the K1 amp is controlling the Eminence drivers very well. Caveat all this with the fact that I am no audio expert.

More to follow once I get to settle in to just listening, rather than tweaking.

[Rudy81]

Here is an update on my setup of the DBB speakers. You may have noticed a few posts back that I have complained about Audyssey 'attenuating' my bass more than I would like. I think I may have been blaming Audyssey for my failure to properly balance the drivers on the DBB speaker. One thing I had not done on my crossover was to set the relative SPLs between the DBB bass bin and my, more efficient, P. Audio horn and driver. I was reading this article by Rane, http://www.rane.com/note135.html, on setting system levels. I took a closer look at the crossover comments and realized I had never used the crossover to balance the SPL from the respective drivers. I had attempted to do that with the amplifier gains, but that was not close enough.

After running various SPL readings on the three active speakers, I ended up with the P. Audio at -5.3 dB and the DBB bass bin at 0dB for the DBB speaker. The center La Scala ended up with the P. Audio at -3.3dB and the LaS bass bin at 0dB. Mind you, that is on top of the gain sensitivity difference already on the amps. The P. Audio drivers are set to minimum sensitivity on the amps. Those things are efficient compared to the bass bins.

I then ran Audyssey again, but with the changes in the output levels. The result was excellent. Much better balance between bass and other frequencies. I no longer feel I have to boost the bass bin using the amps' gain. Listened to a few songs and the sound is very balanced and much more full bodied.

Obviously the DBB bass bin is less efficient than the La Scala bass bin and less than the Khorn bass bin was. I don't know how to easily measure the efficiency, but having been able to make the relative adjustments on the crossover makes the different irrelevant.

The system is sounding very good and my learning continues. I am still very impressed by the P. Audio driver and horn. I currently have the crossover EQ set flat and am letting Audyssey make the EQ changes. Eventually, I can use the EQ to make any fine changes to suit my taste.

[Rudy81]

Since my latest Audyssey run and last speaker positioning I had not watched any movies. Tonight we watched 'From Paris with Love' in Dolby True HD 7.1. Wow, those DBB's shine when it comes to movies. The bass they pumped out during the action scenes, together with the subwoofer was amzing. They seemed much more authoritative than they do with most music, at least the emphasis in the mix must be on the bass portion.

I am more pleased with the results the longer I listen to these beasts.

[sootshe]

Rudy,

Glad to hear these are working out for you.....it's a bold move to replace the K Horns!! [Y]

[Rudy81]

Rudy, Glad to hear these are working out for you.....it's a bold move to replace the K Horns!!

Not too bold a move. I have been modifying the Khorns since I first got them. First the crossovers, then the tweeter, then the mid horn and driver.

In all honesty, I have not missed them and have gained huge flexibility in speaker placement.

[bigrfish]

Rudy, Glad to hear these are working out for you.....it's a bold move to replace the K Horns!!

Not too bold a move. I have been modifying the Khorns since I first got them. First the crossovers, then the tweeter, then the mid horn and driver.

In all honesty, I have not missed them and have gained huge flexibility in speaker placement.

This is a little off-topic, but then maybe it isn't...certainly this is the right group to ask.

When I was in the market for a bass guitar amplifier, I first looked at combos that have amp and speaker in the same cabinet. It did not take too long for me to realize that separates was the way to go. After finding an acceptable amplifier (head, they called it), my attention then turned to speaker cabinets. I listened to 10's and multiples of 10's(up to six of them in one case), 12's and multiples of 12's, but nothing even came close to the Gallien-Krueger single 15" speaker (an Eminence driver) in a rather large ported cabinet. The performance was superior in every way, but especially regarding the tone, freedom from distortion, and the low frequency extension and volume/efficiency, but especially the freedom from distortion. This cabinet handled everything and did it remarkably better. In every area that was important to me the single 15" driver was superior. That's what I bought(and it is now doing double duty as my subwoofer cabinet).

Here's the pertinent question. In my Corn-Scala cabinets, what might be the impact of substituting 18" drivers for the 15's that are currently installed in them. I know there are differences in efficiency or volume out at a given input level, the limits of low-frequency extension capabilities, and the matter of the desirability of having a driver that does what it does with a limited voice-coil excursion range (I understand it is better to have or experience less-vs-more excursion but this might not be right??). If these parameters are taken into account, what might one experience with a well-matched pair of 18's versus the 15's?

Has anyone tried this in a split-bin Corn-Scala installation? Would the dynamics of the volume of the cabinet and port size and configuration be adversely afffected? What say ye???? Currently they seem a little anemic in the bass area if they are straight-wired with EQ and BBE Sonic Maximizer and Yaquin tube output buffer bypassed. The driver I am using is the Selenium 15PW3-SLF 15" which has these Specifications: * Power handling: 250 watts RMS/350 watts max * Voice coil diameter: 2-1/2" * Voice coil inductance: .70mH * Nominal impedance: 8 ohms * DC resistance: 5.8 ohms * Frequency response: 40-4,000 Hz * Magnet weight: 56 oz. * Fs: 37 Hz * SPL: 98 dB 1W/1m * Vas: 9.67 cu. ft. * Qms: 5.81 * Qes: .68 * Qts: 0.61 * Xmax: 3.0 mm * Net weight: 9-1/2 lbs. * Dimensions: Overall Diameter: 15", Cutout Diameter: 13-3/4", Mounting Depth: 6", Magnet Diameter: 6-3/4", Magnet Height: 1-3/8".

All the best,

Chuck aka "Doc"

[Rudy81]

Doc, I'm not knowledgeable enough to give you an answer. However, there are many here who can give you an authoritative answer. In order to get more attention to your question, you might start a new thread with something like "18" woofer cornscala" as a title.

I just took JC's design plans and built the thing.

[Rudy81]

I have been living with the DBBs for a while now and am still extremely impressed with both the bass quality and output of these two way speakers I was able to build. I have finally finished the build and thought I'd update the thread with some pictures. Thanks to all who helped and contributed to the project.

This is the finished cabinet. The camera flash makes the woofers stand out much more than they do with the flash off.

[Rudy81]

This is more of what it looks like in the room.

[Rudy81]

I modified my center La Scala in order to timbre match the front speakers for HT use. Sorry about how dark the picture is, but everything is 'black' and tough to shoot with a basic camera.

[Rudy81]

This is what powers the whole thing. The crossover is set for three speakers in two way configuration. At some point, wallet permitting, I might try a more expensive crossover like an Ashly or a BSS. The Hafler and Crown amps turned out perfect for my application. Very quiet turn on and off, all sequenced with the Furman power supply.

[Rudy81]

Here's the whole enchilada. All in all, it turned out well for my first cabinet build. This picture doesn't do the HT justice. That screen is 10' diagonal and the room is 20' wide.

[mikebse2a3]

Wow..!!! Rudy very nice Speakers and HT..[Y]

mike tn