Tinkering with my Cornwalls

[Thaddeus Smith]

No doubt! ...I've got a 7 day old newborn and a wife on unpaid maternity leave

[moray james]

No doubt! ...I've got a 7 day old newborn and a wife on unpaid maternity leave

Well you don't have to spend a lot to get where you want to go and these could be done over as much time as necessary. Have you seen John's site? Best regards Moray James.

http://www.inlowsound.com/

http://www.tnt-audio.com/casse/paper_mache_horns_e.html

http://www.enjoythemusic.com/diy/1110/oblate_spheroid_waveguides.htm

http://darklanternforowen.wordpress.com/2014/04/13/tractrix-midrange-horn/

Edited August 13, 2014 by moray james

[Thaddeus Smith]

Yup, agreed. I've not seen that site before, but will surely check it out.

[davis419b]

BTW, I like that you always keep me grounded when I come up with "what about.. ?" scenarios.

It just comes out that way.

I think the big draw with the DBB's would be the ability to go 2 way with a 502 or 402 horn. Big bass, big horn. Add a couple amps, an active or passive crossover and let'er rip.

This is the way to go !

[Thaddeus Smith]

Don, what was the setup I listened to in your front room during my visit a few years back? I remember that it was a double woofer bass bin and really big horns, but that's all.

[Chris A]

I think the big draw with the DBB's would be the ability to go 2 way with a 502 or 402 horn. Big bass, big horn. Add a couple amps, an active or passive crossover and let'er rip.

...It may sound worse due to the distance between the single woofer and the top end.

I agree with both of these statements, but the one about the woofer in the lower slot is easy and cheap to try out - and if the DBB bass bin is symmetric, you could just flip the bin upside down and place the midrange and tweeters on top for an "A-B" test. You could also lay the DBB on its side and place the midrange tweeter on top for a listen.

The other thing is the placement of the tweeter WRT the midrange - if you play with this, you can get time-alignment for free. Just move the tweeter back until it aligns visually at the horn-driver joint with the K-400/K55. Then listen, then move the tweeter forward or backward until the soundstage sounds "biggest". This is sort of a big deal once you get it dialed in.

CP25 tweeters are $119 @ to replace the K77s and the difference is startling. However, you'll probably need some sort of active crossover to let you play around with this. There are some pre-owned active crossovers fairly cheap. If you use the following two PEQs with the CP25, it will sound spectacular (after getting the tweeter gains set properly):

PEQ, 5.0KHz, Q: 0.7, Gain: -8dB

PEQ, 12.4KHz, Q: 3, Gain: -11dB

Chris

[Rudy81]

No horn on the DBB's, just holes for two k-33's (or similar). Rudy included some top hats but I won't be using those at this time, instead just resting the horns and crossovers on top of the cabinet.

Was the top hat for P audio ph 4525/p audio bmd 750, if so I have one I would be willing to sell.

Yes, that is what the cutout fits. It is the combination I used and I was very happy with it. Bang for the buck, you can't pay less IMHO.

[Thaddeus Smith]

I'm disregarding some advice and moving forward with my transplant. The cornwall cabs are a smaller footprint to store and this kicks off a platform for tinkering in the future with less up front effort - even if I'm left with nothing more than cornwall's in the near term.

The other thing is the placement of the tweeter WRT the midrange - if you play with this, you can get time-alignment for free. Just move the tweeter back until it aligns visually at the horn-driver joint with the K-400/K55.

This is hurting my brain, likely because I'm used to everything being flush against the motor board. Won't sound waves be bouncing off the mid horn by doing this? Or is the tweeter more narrowly focused than the mid and therefore not an issue? I guess I'll find out as soon as I have everything wired up and playing music.

[moray james]

Bruce has the tweeters on his LaScala set up on a small baffle on top of the cabinet aligned as described. The answer to your question is no, mounting on a flat baffle is a mess that is done because it is easy fast and cheap not because it sounds good. Some simple experiments will show you that all the reasons that you might think are possible terrible issues are far less problematic than mounting on one flat baffle. You can also take the opportunity to experiment with the tweeter orientation (horizontal Vs vertical) The K77 style tweeter is a diffraction horn and is designed to mount vertically for best horizontal dispersion. The K79 and the horn in the Heresy 3 are not far off and I like them in my room better when they are vertical as opposed to horizontal. The horizontal saves a lot of baffle space so you can see the interest in mounting that way. Have fun. Best regards Moray James.

[Thaddeus Smith]

Great little tidbits of info, thanks!

[Chris A]

The other thing is the placement of the tweeter WRT the midrange - if you play with this, you can get time-alignment for free. Just move the tweeter back until it aligns visually at the horn-driver joint with the K-400/K55.

This is hurting my brain, likely because I'm used to everything being flush against the motor board. Won't sound waves be bouncing off the mid horn by doing this? Or is the tweeter more narrowly focused than the mid and therefore not an issue? I guess I'll find out as soon as I have everything wired up and playing music.

Frequencies in the tweeter's band attenuate much more rapidly when reflected off of other objects, due to the shorter wavelengths, so the issues with tweeter frequencies bouncing off other nearby objects is not of a lot of concern.

[Chris A]

...The answer to your question is no, mounting on a flat baffle is a mess that is done because it is easy fast and cheap not because it sounds good...

I'll simply agree to disagree with this statement.  The reason is sounds so good is that you get to time align the tweeter with the midrange for free. I'm pretty sure that Bruce hears it, too. 

Mounting the T-35 (or K77 as Klipsch calls it) vertically results in a bit better horizontal polar coverage than mounted horizontally.  That is a good suggestion, IMHO, but Bruce doesn't use a K77, IIRC.

Edited August 19, 2014 by Chris A

[Thaddeus Smith]

I think he was talking about the factory baffle with everything flush and vertically aligned - it's cheap and easy, but not necessarily the best sounding arrangement.

[moray james]

not sure that I understand what it is that you disagree with? Getting the tweeter off the baffle and on top of the cabinet lets you time align I thought that was what the question was about the time alignment. Or that mounting all your drivers on one baffle is a mess especially with horns simply because it insures messed up time alignment? I mentioned Bruce as he has done this and yes you recall correctly Bruce switched to one of the APT Eminence tweeters the 50 I think but I am not sure about the model. Best regards Moray James.

PS: I placed my Heresy 3 tweeters up on top of my H3 and was immediately impressed bu the improved sound quality of aligning the tweeters with the mids. The tweeters have never gone back to the stock location since. I have done the same with mid horns aligning with the woofer and was just if not more impressed with the results on my KLF20.

Edited August 19, 2014 by moray james

[Chris A]

I think he was talking about the factory baffle with everything flush and vertically aligned - it's cheap and easy, but not necessarily the best sounding arrangement.

A separate baffle like Bruce uses is a flat baffle.  I assumed the little baffle that sits on top is the one in the statement, not the front of the Cornwall cabinet.  I agree with his statement if he is talking about the Cornwall cabinet.

Edited August 19, 2014 by Chris A

[Thaddeus Smith]

I migrated the parts over a couple of weeks ago. So far, so good. Bass is good, different, but good. I think it's likely a result of having the speakers tighter into the corners, raising the woofer up to shoulder level, and spreading the speakers further apart. Sound stage is also better/wider, but I attribute that once again to the speakers being further apart than before.

 

The sound stage is good, but not quite where I want it to be. I still hear some localization to the left and right speakers and wonder if it's due to horn placement up top. If I post a pic later (forgot to snap one last night) of the driver/horn positions do you guys think you can give me some tips on how to tweak angles and lateral placement (side to side, front to back)?

 

Overall, it's as good or better than when I was using the cornwall cabinets so no loss there. It just seems a bit more finicky. I think if I can get the top end dialed in I'll just add the secondary woofers and tweak the crossover to accommodate the extra load. I really like having just my little frankenstein amp/FLAC streamer and a power supply sitting between the speakers. Adding the complexity extra amps, digital crossovers, cables, etc just doesn't appeal to me at this time. I very likely will change my mind next week (as Carl knows all too well)

[minermark]

Sounds like you have a fun project!

When i started dialing in my EAW stacks, they are 8'+ tall, mids are above my ear level when sitting down, one of my mods to these stacks was to give up one 8"mid in the upper stack(s), and installing K400s in each stack, that got my horn sound back. problem then was they did not sound like they were enough, almost like i needed to double up on the K400s. 

When sitting, the horns were above my ear level by aprox 2', so i raised the back end bracket on the K400 to angle downward aprox 10degrees.

I have found having those horns focused on your listening position made all the difference in the world.

[Thaddeus Smith]

Good info. The bass bins are right about the same height as a khorn bass bin and I currently have woofers in the upper chamber - so they're pointed at shoulders/head. Both squawker and tweeter are directly on top, so about ear/top of head height angled at 45 degrees.The permutations seem endless and it's melting my OCD brain, so I'm thinking you guys can see my default setup and maybe provide feedback on some proven positioning that I can launch with and then begin the "sit down-listen-stand up-tweak-measure with tape measure-duplicate with other speaker-sit down-listen" cycle.

 

 I'll post a photo tonight so you can see what I've got to work with. 

[Thaddeus Smith]

Alright, here we go. I know it's impossible to know without actually hearing, but for you guys that have played with driver position outside the boundaries of a fixed motorboard - what would you change as a baseline from your experiences? Everything is currently lined up at 45 degrees to the corners. Bass bins will stay fixed, but the horns can obviously be aligned in any manner.

 

Left

 

 

Right

 

 

From the listening chair

 

[Chris A]

Alright, here we go. I know it's impossible to know without actually hearing, but for you guys that have played with driver position outside the boundaries of a fixed motorboard - what would you change as a baseline from your experiences? Everything is currently lined up at 45 degrees to the corners. Bass bins will stay fixed, but the horns can obviously be aligned in any manner.

 

I'd try moving the midrange and tweeter forward until the horn-driver interface joint is approximately lined up with the dust cap on the woofer below, or even a bit further forward.  This may be easier if the midrange and tweeter are mounted temporarily to a piece of plywood/MDF/wood that they can rest on.

Edited September 8, 2014 by Chris A