whtboy

I'm curious how much the impedance plots vary between drivers of the same model. EDIT: Bob, were there any other components (such as part of a crossover) in the circuit when you did the test, or is this the raw plot of the driver on the wire?

Excellent! Thanks for the tip. This is looking much better now. Yes, according to the pdf Bob wrote up it appears the driver was loaded in a K400 horn for the test. Is it common for drivers to have really uneven impedance plots like this? -jacob EDIT: man, microsoft sure makes some great office applications. too bad they don't stick to what they know and just leave operating system design to the cs engineers =)

Cool, thanks Bob! Can't wait to get my new diaphragms and caps in! -jacob

Bob, Do you know what the stock crossover points are on a stock Cornwall I? -jacob

I can't get these Excel charts to work to save my life. I'm guessing there isn't a way to get it to interpret the X-axis on a logarithmic scale. I put the numbers into a worksheet and made a chart of the values below 2kHz if anyone is interested. Are there any free tools out there that can generate plots with a logarithmic X-axis? -jacob

Uh, scratch that. I didn't see the big peaks until I started entering the numbers into Excel. Plots coming shortly! -jacob

Does the impedance on a midrange driver not vary as much as on a woofer normally? Or perhaps it doesn't get really ugly until you reach frequencies below where the mid would normally operate anyway? I was expecting it to be all over the place. Thanks Bob!!! -jacob

I've done some searching but haven't found any impedance vs. frequency plots for the K55 or K77 drivers. Does anyone know where I could find some? I don't have any highend test equipment. Thanks! -jacob

1976 Cornwalls, born the same year I was =)

I've been reading a bit about the complications caused by complex passive crossover networks and the benefits of active crossovers combined with bi- or tri-amplification. I'm not an electrical engineer, so please let me know if any of my reasoning here is off. I've got a Yamaha 5 channel A/V receiver. The amp on each channel is rated to 75W rms but the power supply is only rated to 210W so I'm guessing my max simultaneous rms output is closer to 50W if I run 4 channels at the same time. This receiver has individual preamp-ins for each of the amp channels so you can hook it up to an external decoder. I was thinking... I already have a PCB for a stereo 2-way 24dB/octave Linkwitz-Riley active crossover that I bought from ESP a couple years ago - http://sound.westhost.com/project09.htm For just a little bit of cash I could build this crossover and use it to split a line-level stereo signal into L-high L-low, R-high, R-low. If I set the crossover point to be the same as the stock cutoff between the woofer and squawker, the woofers can be driven from 2 of my Yamaha's amp channels without any passive crossover components at all. From what I have read, passive low-pass filters are bad because they interfere with an amplifiers ability to damp some sort of feedback from the woofer, meaning the amp has a harder time controlling how the cone actually moves, which results in sloppy, muddy bass. I'm guessing I would still need a passive network to split the signal between the squawker & tweeter, but whatever I do there will have the benefit of the signal already having come through a steep, active high-pass filter lower in the spectrum (which won't interfere with the math of the passive network). Given that, I'm hoping I might be able to get away with a simple network here, which I've read is a good thing except for the amount of signal that bleeds over the gentle slopes. Granted, this would completely ruin my ability to use my receiver to switch between sources (which at this point is a DVD player & a CD player) but if there is a big gain to be hand in sound quality I could probably build some sort of mechanical input selection into the crossover box. If this sounds like a decent plan, I think I could do it all for under $100 plus my existing hardware. EDIT: and of course I would be giving up the ability to do any sort of multi-channel HT stuff with my existing hardware, but I think music is generally better for a person than movies anyway so... What do you guys think? -jacob

Ouch. Uh, yeah, I think I'll definitely be sticking to a simple cap upgrade for now... it's going to be a while before I can drop > $400 on a pair of networks! Thanks guys! -jacob

What are the price ranges for the new networks most people are using? I just dropped Bob a check in the mail for new diaphragms & caps, and I will rebuild my stock stuff as soon as the parts come in, but I'm still interested to learn more about what's available and how much you guys charge. Thanks! -jacob

Just in case it helps to clarify my current condition, my Cornwalls were manufactured in '76. From what I've read I'm guessing my caps are in pretty bad shape. Do old caps just make the souund more harsh or do they actually affect the slopes and/or crossover points each driver sees? -jacob

Are there price lists anywhere? It appears the search function isn't back up yet. -j

Hi all, I just got an old pair of Cornwalls. One tweeter is dead and I am ordering a pair of diaphragms tomorrow from BEC. I'm thinking about buying Bob's crossover rebuild kit which provides new caps and mounting parts. Can someone give me an overview of the pros/cons between just doing a polypropylene cap upgrade vs. going with one of the alternative xover designs available from DeanG and "friends"? In the end I'm hoping for more natural detail and clarity, and (unless I don't understand basic loudspeaker design) to not hear male vocals coming from all three drivers at the same time. Thanks! -jacob

This is a long post - I tried to make it as concise as possible but... We watched a couple movies today & I didn't notice any EM interference like I did with my Ensembles. The left tweeter is out though. I'm going to order a new set of diaphragms and possibly new caps from Bob Crites tomorrow. I have a lot of mixed feelings at this point. These are definitely the best speakers I have ever personally owned - much better dynamics than the Ensembles they replaced. There seems to be little frequency/signal seperation between the woofer, squawker and tweeter. Listening to "The Full Custom Gospel Sounds" by The Reverend Horton Heat the lead vocals are reproduced through all three drivers. The vocals coming through the woofer sound like I would expect vocals to sound being played through a 15" paper cone woofer - muffled with a hollow echoey feel. The same vocals through the squawker are full volume, reasonably detailed, very "in your face" and clear. Same vocals again through the tweeter are very clear, not quite as loud as the squawker, and also backed up by all the really high pitched stuff - breath, lead guitar, cymbals, etc. Is it normal for some midrange frequencies to be reproduced at audible levels through all three drivers, or is there something wrong with my networks? I don't have the vocabulary to accurately describe the difference between the sound I was expecting and the sound I have. To explain my two points of reference, I have heard two setups that really stood out in my mind. The first was my uncle's Cornwalls back around 1988. He had a moderately priced amp, preamp (and a dynamics expander thing - but I think he had it turned off) and the first CD player I ever heard. He played the Wall and some classical piece - both had a huge sound, very big, dynamic and (to me) real. The dynamics were incredible and it was like nothing I had ever heard before. My second memorable experience was a pair of Martin Logans (along with some ridiculously priced electronics, each component probably costing more than my mom's car) in a high end audio store somewhere in Houston. They didn't have the rock concert-like sound of the Cornwalls, but they did have a very delicate, extremely detailed and life-like, beautiful sound. My current setup consists of the Cornwalls (10P980 & 10P981, running on the original network and with only one tweeter), a Yamaha Natural Sound A/V receiver and a Sony CD player. D/A conversion is being done in the receiver. I'm using 10' lengths of 16 gauge Monster cable between the receiver and cabinets. I've got the speakers about 6" away from the back wall, approximately 36" apart and slightly toed in so my listening position is on-axis. My listening spot is about 7' back from the cabinets on a couch against the opposing wall. They sound good but not nearly what I was expecting. Some albums don't sound very good on them, but I'm starting to think some recordings are just a *lot* better than others. Even on the better sounding recordings though, I would say the sound is sort of veiled, kind of how is sounds when you are listening from another room, but not quite that bad. Some sounds will come across with a reasonable amount of detail while others seem muffled and flat. It isn't *as* bad with the grills off, but it's still there. Some of the midrange frequencies seem to resonate and are produced louder than the surrounding notes, which is very annoying/painful when the average sound level is right at the edge of my comfort zone. Obviously the fact that one of the tweeters is out doesn't make evaluating them any easier, so I'm going to withhold final judgement until I get new ones in. Is it possible my squawkers are "worn out" or experiencing some other phenomenon that would make them sound less than ideal? Are my aging capacitors to blame? How much of a difference would it likely make if I replace them? How much difference does an alternate network design make? Has anyone had any luck with adding absorptive material to the inside of the cabinet to help minimize the hollow/resonant midrange sounds that come from the woofer? Is my "Big Mac" receiver really to blame? I'm inclined to scoff at high end electronics but that's probably just because I can't afford them. Lastly, is it possible my 29 year old ears just don't hear the details as well as they did when I was twelve? I still seem to be able to hear many high pitched sounds other people can't, but I have a constant ringing in both my ears with the right ear being about half an octave higher than the left. Or maybe I'm just not as impressionable anymore? I'm sure there are a lot of different opinions on all this, but any opinions that are based on real experiences are better than what I've got now - which is no clue! What do you guys think? Thanks for all your input!!! -jacob

Here's another pic

Got 'em! Thanks for the hookup Jeff!!!

woohooo!!! the forum's working again!

......testing

Is there an overview somewhere explaining each of the following? - the different crossover types Klipsch put in Cornwalls - recommended budget component upgrades (i.e. upgrading caps and such) - the different options for new/custom crossover networks (A, AA, super AA, supermodified AA, AA-, etc.) I've done some searching/reading but found nothing complete. Thanks! -jacob

Would a single K-55 squawker work well as a budget center channel speaker between a pair of Cornwalls in a small room? I'm gonna be strapped for cash if I get these Cornwalls and I'm still going to have to get a new set of tweeter diaphragms from BobC. Seems like the majority of the center channels speakers out there can't match the 98dB sensitivity of the Cornwalls and the ones that can are pretty expensive. I'm not so concerned about the high end (can always add a tweeter later) but I'm not sure if the K-55 will go low enough to make male vocals sound good. Has anyone tried this? Thanks! -jacob

Uh yeah, like you've never done that!

I'm a sucker for immediate gratification, no patience whatsoever. That has bitten me a number of times and I often get things I don't like in the long run. I'm going to put the cash in an envelope, stick it somewhere safe and keep watching. Thanks! No one has come out and said it explicitly, but it seems like people have a more faith in the older Klipsch speakers while some of the newest/latest ones don't seem to offer as much bang for the buck. Is that true? -j

And after this no more big purchases until I'm debt free!