Improving sound of built-in Cornwalls

[Gordon W]

I have a pair of ca. 1978 Cornwalls which are built into bookcases. I know this is not the best arrangement for optimizing acoustics and I'm wondering if there is anything I can do to improve things, short of relocating the speakers (not an option). Specifically, I'm considering the following: The area behind the speakers is open and accessible from the rear - would it help to build a sub-enclosure with air space around the speaker cabinets and raise them up on cones? I would be grateful for feedback on this or other options. If it makes a difference, I'm using a 3.5 watt Bottlehead system to push the Cornwalls.

Thanks in advance,

Gordon W

[dbflash]

Gordon,

Welcome.

Your amp and speakers are a very good match so I don't think that is the problem. What exactly is your problem? Too bassy? Sounds flat?

In the present position are your speakers toed in any or are they firing straight out?

How much distance between the speakers.

I know you are not going to like this, but here goes.

I just moved my Cornwalls from one room into another. In the existing room the speakers were 89 inches apart, 18 inches from the side walls and 24 inches from the back wall. They sounded ok, but not that great.

I moved them into another room. The speakers are 8 feet apart, 4 feet from the side walls and 22 inches from the back wall. They sound awesome. It is the best my system has every sounded.

The Cornwalls need space and IMHO don't liked to be boxed in.

I hope someone will respond to your question who has the same setup as you do.

Danny

[Frzninvt]

You need to be able to toe them into the listening area and in your current arrangement that is not possible. Corner placement is obviously the best choice.

It is apparent that you worry more on how they look in your environment so until you get up the gumption to move them out of the cubby holes there in you will have to deal with the compromised sound. Altering the cabinet volume will make matters worse since they were designed with the optimal internal volume from the factory.

Better feet (grippers or spikes) may help a little some, reworking or replacing the old crossover /components/networks will certainly improve them significantly sonically but you are still stuck with poor positioning.

[DrWho]

What about the sound that you currently have don't you like? There's probably a lot of things that can be done in your situation, but it would be pointless if there wasn't a problem in the first place.

[colterphoto1]

perhaps dampen the air space between speakers and bookcases with eggcrate foam. It is my experience that the vibrations emanating from the cabinet surface (quite large panel in the case of Corns), housed in an outer box (bookcases) causes a 'tubbiness' or 'honkiness' sound which is a very nasty little standing wave indeed. Opening the backs of cases could help, but try dampening the vibrations with some foam of some type, even pillows or blankets temporarily just to test the theory.

Also the toe in theory is a good one. Corns have very wide horizontal dispersion and you need to keep the mid horn sound from striking the side walls of the room before the sound gets to your ears.

Let us know how it works out please.

Michael

[Gordon W]

Thanks to everyone for the assistance so far.

I can see I should have provided a few more details, so here goes. My Cornwalls, of which I am the original owner, are spaced 26 feet apart in a room 18x26 and they are in fact toed-in toward the listening position which is centered on the opposite wall. Only one speaker is actually in the bookcase, the other is on a stand in the corner of the room but will eventually be built in as well. The bookcase speaker is also in the corner of the listening room but, while the front of the speaker is flush with the bookcase, about 18 inches off the floor, the speaker itself is actually sitting on a shelf in a closet behind the bookcase, if that makes sense. This is where I'm wondering about building a kind of "false corner" surrounding the speaker.

The reason I think I can improve the acoustics is because I have experimented with placement of the other speaker by moving it out of the corner, getting it off the floor, etc, and saw a definite improvement in depth and width of the soundstage as well as improved bass and midrange.

And ,yeah, I know I should have a purpose-built, dedicated listening room, but,hey, you make do with what you've got. I'm in the middle of upgrading my sound system after nearly 30 years and have built new speker cables, interconnects, tube preamp and amps (was using a McIntosh MA6100 which is now my phono stage), new phono cartridge and SACD/DVDA player, and tweaking the speakers is my current focus. I may have to live with what I've got, which is by no means bad, but if I can coax a little bit more of that sweet sound out of my old boxes, so much the better.

Thanks again to everyone for replying.

Regards,

Gordon W

[yaffstone]

Check out the post on Free the Dope from Hope. There's a section on adding a 3rd channel (center). This might be a significant improvement to your system especially since your room is rather large.

[Tom Mobley]

26 feet apart? See yaffstones comment above. You really need some kind of center speaker. Any chance you could round up a Heresy or another Cornwall for a test drive? Where are you located?

[colterphoto1]

oops double, sorry

[colterphoto1]

I still wouldn't enclose it any more than it is already. I wonder about your height- 18" but if they are sitting horizontally, probably about the same as a vertical cabinet- you want the mid and tweets at about the height of your ear when seated. If one's in the corner of the room, it's probably as boomy as you'd want, so I wouldn't extnet the corner 'horn' any more. Remember to think of the corner of room in terms of % of spherical space. Open air is full sphere, against wall 1/2 sphere, corner (raised) is 1/4 sphere, corner on floor is 1/8 sphere. The tighter the 'horn' you're firing into, the more potential for boom and possibly standing waves. For smoother response, try a different dimension from each wall and floor (on floor, one foot from one wall 2+ feet from other wall) inches make huge differences.

Agree with the center channel to fill in. Wide soundstage is one thing, but dude, you're Madison Square Garden at 26'. I think that 12-15 ' between Corns is about right for two-channel. I tried to use the rule 25% of room, corn, 50% of room, corn, 25% of room. My room is 30 feet wide, so corns ended up 15' apart and it sounds about right. Can you move em closer?

Michael

[Gordon W]

Unfortunately, the center channel would be in the middle of my fireplace!

But, even with my room dimensions I think I can achieve a decent soundstage and fidelity, based on experiments with minor movements (away from the wall) of one of the speakers, which yielded a significant improvement. If I can figure out a way to "trick" the built-in speaker into thinking it's in a corner perhaps further improvements can be had. I'm working my way through the Dope From Hope newsletters and may find answers there. Thanks for the input.

Gordon

I'm located in the Ozarks, NW Arkansas

[yaffstone]

What about above the fire place mantle, or to one side of the hearth? Cornwalls won't respond to corners (true or false ones) like the khorns. They're direcly ported to the front and not to the rear and sides like the corner horns.