revjac

Dean - Thanks for going to the time and trouble of posting that article. I have read it several times over the past few weeks but other than saying that adding a panel to the rear (which I will do) will help it doesn't really address my query (making the rear panel a constrained dampening sandwich). Maybe I should just go ahead and try a few things on my own. I don't seem to be getting any specific, pertinent feedback to the proposed premise in my original post.

I have not, nor did I ever, intend to make a significant change to the interior dimensions of the cabinet. Nor do I have any idea how my original premise and consequent inquiry manage to slide off into this sidebar - oh wait - yes I do know - speaker guys. We're speaker people here. Of course the subject matter is going to change. It's what we do fer cryin' out loud! Phew! I almost forgot there for a second. And now, for me at least, back to considerations of a constrained dampening layer for the rear panel.

noooooo! Unless I steam it.... nope - ain't gonna' doit. []

It is a very good article. I've read it several times but other than the addition of the back panel doesn't really address my issue. I'm not looking for lower bass frequency particularly. In fact I'm quite happy with the bass output. Perhaps, if I used the Cornwalls for home theatre applications, then that might change things but I am only using the speakers for 2 channel stereo reproduction so there's not a lot below 40hZ that I care much about. And my collection of pipe organ music is very minimal. Except I do have "Antiphone Blues" and that needs some bottom. I would like what great sound there is now to become a trifle more taught in the nether frequencies. If and when I finally find Ray Brown's "Soular Energy" album I want his bass to talk to me in well-enunciated and articulate tones.

Mike - anticipating any ideas you bring forward. I have no intention of changing the interior size unless I absolutely have to but there's gonna' be a panel on the back.

It would never have occurred to me to change the interior cabinet dimension on purpose by adding the 2nd rear panel from the inside. Hmmmmmmm. I would think that making those changes would be too much of a hit-miss venture. Even with some sort of box plot software involved the whole scenario smacks of too much of a skill level I do not possess. Just the fact that I'd like to remove the current "paper" batting and replace it with (my favourite) old-style natural fibre (wool) batting is giving me some pause. I have every intention of doing it but the original paper batting will be stored carefully just in case it needs to be re-installed. I do expect that adding that that second rear panel will have a positive effect. Don't ask me how I know this - just call it a gut instinct - although I've been wrong and right before it hasn't been 100% one way or t'other. I think I've been more right about these instincts but that's only because of a pile of research and some considered input from others higher up the R/D chain than I. I do believe that making a layered acoustic sandwich on that back panel is a good idea. Where I'm stuck is determining what the filling in that sandwich will be. I know quite a few higher-end speaker designers have incorporated at least a variation on that idea so it's not like I'm coming up with something new. As well, my thinking and past experience says that the cabinet resonances might be well-served by having the second additional panel at least of a different thickness than the original and most likely also of a different material. The thought process here being is that different thickness and material will serve to dampen/absorb different resonant frequencies than those being handled by the original panel. It's all speculative. And I like it.

As I move down the road with my Cornwalls I'm hearing that (to this point) most of the recommendations regarding mods and tweaks have been a positive experience. Running a hardwood brace across the back of the motorboard (I bolted them on instead of just screwing them in from the back) was a particularly good idea. I would now like to address the rear panel. I believe that the addition of another panel will tame some of the resonant flex. What I would like to get is from the forum populace is some input on is making that rear panel a "sandwich". As in something between the existing panel and the panel I plan to add. The consideration here is that an additional panel may never fit flat against the exisiting panel and some sort of acoustic dampening material between the two could be a good idea - for any number of other reasons as well. I've done some research on some dampening material. Something viscoelastic seems to be the best route, whether that would be some sort of sheeting or a spray-on material. Then I cast my eye on a roll of thin cork sheeting I have lying about. Later that same day I chanced to be in my local big utility hardware store (RONA) and saw a roll of sound damping material , about 3mm thick, made from re-cycled natural fibres (cotton, wool, et al). I also have a quantity of thin closed-cell foam that might be worthy of consideration. All these with an eye to a minimal financial output. (I'm not exactly made of the long green nor does it fall like manna from the heavens hereabouts) Therefore lads, could I open this small dilemma to your consideration and perusal and, consequently, feedback?

First off - Use Cat 5 E! If it doesn't have the "E" then it isn't plenum rated which means the insulation isn't teflon I gave it a shot a few years back. I had a bunch lying around that I scooped from some reno construction project going on in a bar while I was doing an interactive satellite install. I stripped out a few twisted pairs to build some interconnects to go from a QUAD pre-amp (DIN out) to a pair of RCAs. I just left the pair twisted, wrapped 'em in plumbers teflon, pushed that through some copper braid stripped from a roll of RG6 coaxial cable and I wrapped it again in more teflon. Soldered on the connectors and away I went. Worked just fine. Better than the cable that came with the pre-amp but not likely as good as some $$$$ wire. Then I made a pair of 3m speaker cables. I didn't do much more than cut 6 lengths of (about) 3.5m. I just braided three together for the each side. Didn't strip the blue insulation off or nuttin'. Loose braid - say about a turn every 2-3" - Stripped off the ends. The solid colours went to Neg. and the others went to Pos. Put on some half decent Bananas and stuck 'em the rig. My partner (she of the better "ears") and I both agreed that the sound was better than the DH Labs T14 I had in up to that point and I really do quite like that wire!! I'm going to use some of the DHlabs to re-wire the Cornwalls. The woofers specifically. And then I intend to use some CAT5E to do the mids and the tweet. Likely a single pair for the top and likely two pair on the mid-horn. Just to see what happens. Anything will likely be better than what's in there now. If I don't like it I'll pull it and try something else. Tweaking - even if it always isn't for the better - is still fun and a learning experience.

If they sound better then it's better to him and not necessarily better to anyone else. But I'll give him the benefit but I doubt it - [:#] Did he mention what sort of box plot he used to get the interior dimensions - if he used one at all? And they're ugly. Damn. (I don't much care about "looks" but I had to throw that in for SWMBO. )

While I agree a lot of them cater to the advertiser in some fashion or degree I do find I mostly enjoy "UHF" (out of Canada and don't pull a lot of punches - if it sucks they pretty much say so) and The Absolute Sound (maybe for the style of their writers more than anything but a good rag overall)

Sooooooo - My first set of Cornwalls sound absolutely marvellous! I decided to open them up and have a look, figuring I'd maybe rotate the bass drivers or at least tighten the screws and have a general looksee. Open the first one (SN 30X232) and notice right away there's not enough wire to rotate the K33E and the screws are, not surprisingly, a bit loose. Nothing that a 3/4 turn didn't fix. I'll likely mod the wiring anyway so I'll leave the K33E be for now. K51V mid was tight, K77M tweeter as well. Saw where a piece of bracing would fit across the motorboard/front baffle, crossover mount screws were a touch loose - tighten those, ran a strip of some non adhesive sealant around the inside rear cabinet perimeter because I always do - whether it needs to be sealed or not. Must be an OCD thing. Re-attached the rear baffle. Went on to the other cabinet (SN 30X273). Pulled the back off. K77M tweeter - check. K33E bass driver - check. K55V mid horn - ohhhhh. Wait a second here. That's not right. That's not the same as the other one (this is where the "JustMyLuck" part comes in. This kind of thing happens to me all the time. I must be a human magnet for this.) Damn. Anyway, tightened the K33E screws, and other stuff that needed it, ran the sealant strips and closed it back up. I can't hear the difference between the two. However, I find it rather strange that 2 units built that close together would have different horns. There isn't any physical indication that a replacement has been dropped in at any point. The other thing is that the 232SN has what I assume to be the later model K51V driver while the later SN 273 has the the grey capped K55V. I could even understand a new model year moving from the K55V to the K51V but these are both "X". (I understand that I could be wrong about which order these units would have been manufactured and installed so just bear with me. If I am then transpose all the stuff I said and just drop the stuff that doesn't matter.) I suppose it doesn't really make any difference since I can't tell the difference but here's the thing. I know one is different from the other and that not only bugs me but is affecting my overall listening enjoyment because I'm thinking about it. All the time. It's like one of those fricken ear worm songs that gets into your head and won't go away. So now what? My first thought is to instigate a trade with someone and at least get the same mid-horn in both. But which one? My initial feeling was to trade out the K55V. After having slept on the thought now I'm not so sure. I hereby throw my quandry on the mercy of this august and catholic body of Klipsch afficiandos. Sort of a WWACOD? - What Would A Cornwall Owner Do"? Please tell me!

There is absolutely NO way I can fit them in the main rig upstairs but then, since I'm down here 8-10 hours a day why shouldn't they be down here with me?!?!? Anyway - the aforementioned "W" was, prior to my actually bringing them home, quite excited. But I don't think she really knew how big they were. Soooooo - I made her pick a favourite piece of music (Loreena McKennitt as it turned out - excellent choice because of her use of instrumentation). I started the music and then led her into the chair with the promise of keeping her eyes closed so she'd hear before she saw. (this is a good ploy gentlemen) She was mightily and thoroughly impressed with the sound (she hears better then I and is "musically inclined" - ya know - perfect pitch and all). She did give up a bit of a start when she asked to see them after three songs.I quite expected that though. They are big. Now I need to search and peruse the tweaks and upgrades section. I'm sure the first thing I'll do is rotate the bass drivers 180 degrees because I imagine that's never been done and I'll likely dampen them while I'm in there. Then there'll be some bracing across the front baffle. I can already hear that that's needed. Some determination of placement, distances, toe-in or not.....and so on. I'll have a look at the crossovers down the road a bit and think about the upgrades there. In the interim I'll be nose-first and deep into the Klipsch forums search engines regarding anything "Cornwall" But boyoboyoboy' - Miles's horn shore do sound purdy this Sunday mornin. As do Kottke's gitar and EmmyLou's voice and Loreena's band and Derek Trucks' band. Life is good to-day.

Ohhhhhhhhhhhhhhhhh my! I see!

I flipped into the K forums just as I was looking up from "The Absolute Sound" picks for 2006 product of the year. Page 51 actually - Digital Sources of the Year. And staring back at me from the page as I was looking up at your message was the Rega Apollo CD player - US$995. This isn't the only time I've seem some very heady reviews about this rig. The general impression I get from reviewers is that it does perform well above its price point. May be well worthy of your consideration

She's lived with Coral Beta 8 FRs in a rear loaded horn cab and she's lived with a pair of Maggie III-As so she might survive the Cornwalls. She's been "advised" as to the size - whether that's going to sink in before or after she sees them may have to wait until the actual visceral impact of their size confronts her. It'll certainly be a trifle different than the stand-mounted LS3/5a pair that went into the main rig so that there was room for the "Xmas tree adjustment" in what is usually the the listening space. I might bring them down here into the basement/shop/office/listening room for a bit first - mostly because I'm down here for 8-10 hours a day and it does make some sense to have them where I can hear/enjoy them all day.Even if the fit might be a touch tighter. I suppose I should get busy with some searching on optimum set-up distances. There'll be about 2m between centres in the office and that'll increase to almost 3m in the main rig (necessity from the ownership of a rather large screen TV) We'll see how it goes!!