Clipped and Shorn Posted January 1, 2008 Author Share Posted January 1, 2008 So here is my plan for Corn redo or makeover with Cab intact, so far: 1. Try out a new B network, A/B compare, speaker to speaker with the old network. 2. If that is satisfactory, build a new B network. 3. If still not quite it, I will replace tweeters and X @ 4500, building new network accordingly. I seem to recall someone mentioning that right above 4500 hz is where some potential problems start with the K55, so that seems like a good plan, and if BEC tweeters handle everything above that, it seems like a possible solution. So is the theory that the frequencies between 4500-6000 hz give rise to the majority of harshness issues here? In the bass dept, how much and what kind of improvement might one expect to get with your woofers Bob? -9239823495 % 9236499 Quote Link to comment Share on other sites More sharing options...
BEC Posted January 1, 2008 Share Posted January 1, 2008 C&S said: "In the bass dept, how much and what kind of improvement might one expect to get with your woofers Bob?" Not much improvement in the Bass with my stamped frame woofer. Really with it any improvement would be just new woofer compared to old woofer both built originally to the same specs. With my cast frame woofer, improvement should be small, but there. It is slightly more efficient at the low end. Might get an additional couple of hz lower. I don't think any woofer is going to give you dramatically better bass without cabinet changes. Having said that, customers report more improvement using the cast frame CW1526C than I would have predicted. Bob Quote Link to comment Share on other sites More sharing options...
Deang Posted January 2, 2008 Share Posted January 2, 2008 "I seem to recall someone mentioning that right above 4500 hz is where some potential problems start with the K55..." Yes and no. On a plane wave tube, the response of the spring loaded K-55 falls off pretty fast after 4.5kHz. However, once mated to a Heritage horn the response goes out to 6kHz. Those horns lift the falling response with increasing frequency (collapsing verticals). The downside is that it's getting a bit beamy as it approaches the crossover point. Lowering the crossover point advantageous if you have a decent tweeter that can handle it. There aren't many. Bob's CTS-125 can handle it, and popular tweeters like the JBL and Beyma can handle it if you go with steeper slopes. Quote Link to comment Share on other sites More sharing options...
Clipped and Shorn Posted January 2, 2008 Author Share Posted January 2, 2008 There aren't many. Bob's CTS-125 can handle it, and popular tweeters like the JBL and Beyma can handle it if you go with steeper slopes. Between Bob's CTS-125, the JBL, or Beyma, which is the easiest physical retrofit. Does the CTS-125 fit right into the existing slot? -87263 # 27653 Quote Link to comment Share on other sites More sharing options...
fini Posted January 2, 2008 Share Posted January 2, 2008 Does the CTS-125 fit right into the existing slot?Yup! Quote Link to comment Share on other sites More sharing options...
BEC Posted January 2, 2008 Share Posted January 2, 2008 OK, have to nip this in the bud. Dean renamed my tweeter the CTS-125. It is the CT-125. As in "Crites Tweeter". Bob Quote Link to comment Share on other sites More sharing options...
jwc Posted January 2, 2008 Share Posted January 2, 2008 Wait! I thought it was the CRT-125. "Crites Replacement tweeter" with a special price of $125/pair for forum members?[+o(] hehe jc Quote Link to comment Share on other sites More sharing options...
BEC Posted January 2, 2008 Share Posted January 2, 2008 How about the CTC-125? That would be the "cryogenically treated" model that I chill overnight in the freezer. Those are $200.00 each. Need to make those payments on my new Lincoln. Bob Quote Link to comment Share on other sites More sharing options...
DrWho Posted January 2, 2008 Share Posted January 2, 2008 "...and 18 dB / octave on the woofer. This is because the voice coil inductance of the woofer driver is integrated into the woofer filter as a third inductor forming a 3rd order filter...1 mHy in series with 6 Ohms..." I've tried, but I just can't buy into that. Yeah, it doesn't work that way. The only way it'd be 18dB/octave is if the woofer was rolling off acoustically...the power response is rolling off, but the beaming of the driver keeps the on-axis from falling. Quote Link to comment Share on other sites More sharing options...
Deang Posted January 2, 2008 Share Posted January 2, 2008 Oops, sorry Bob. [:S] Mike, can you think of another reason why you might not want to do that? Quote Link to comment Share on other sites More sharing options...
IB Slammin Posted January 2, 2008 Share Posted January 2, 2008 TowncarCrites, Just place them on the porch. Low of 11 degrees tonight.[ip] tc PS: Better keep the mules. With oil at $99.62 per barrel, you might need them to pull the car.[sn] Quote Link to comment Share on other sites More sharing options...
DrWho Posted January 2, 2008 Share Posted January 2, 2008 Mike, can you think of another reason why you might not want to do that? Do what?(or is there another Mike?) Quote Link to comment Share on other sites More sharing options...
Deang Posted January 2, 2008 Share Posted January 2, 2008 "...and 18 dB / octave on the woofer. This is because the voice coil inductance of the woofer driver is integrated into the woofer filter as a third inductor forming a 3rd order filter...1 mHy in series with 6 Ohms..." I've tried, but I just can't buy into that. Yeah, it doesn't work that way. The only way it'd be 18dB/octave is if the woofer was rolling off acoustically...the power response is rolling off, but the beaming of the driver keeps the on-axis from falling. I'm pretty sure you're the only Mike in this thread. Quote Link to comment Share on other sites More sharing options...
DrWho Posted January 3, 2008 Share Posted January 3, 2008 Well the beaming of the driver is just a behavior of direct radiators...it's not exactly ideal. So basically, you go with a woofer(s) section that is as large as possible until the polars line up with the polars of the MF/HF section. If you can get them lined up pretty well, then your crossover just needs to bring the system to flat on-axis and the power response takes care of itself. Usually you try to stay away from the inductance rolloff of the woofer because the inductance modulates and most woofers are near their cone-breakup region too. Quote Link to comment Share on other sites More sharing options...
Clipped and Shorn Posted January 8, 2008 Author Share Posted January 8, 2008 Anyone ever try taming Cornwalls simply by adding an L-pad to control Squaker level, and another L-pad to control Tweeter level. Maybe that is all that is needed here. (?) Maybe it is just a matter of finding one's own custom balance to fit one's ears. -pqoiuwer & uagslk Quote Link to comment Share on other sites More sharing options...
Clipped and Shorn Posted January 20, 2008 Author Share Posted January 20, 2008 OK, I have finally made peace with my Cornwalls. Bob Lee was kind enough to loan me his new Vcap B networks and I did an A/B comparison , and even though the new B networks were a bit more airy and transparent, it did show me that my old type B crossovers were not that far out of line (an otherwise acceptable touch of muddiness compared with the new nets) . (Since that touch of mud actually works in its favor) I think I will retain the 1978 Cornwalls as stock and use this system for what is best, and that for me is playing most (small group) jazz recordings at normal volumes. What it will not be used for is playing latin-jazz at critical mass volumes high enough for me to play congas along with (I was, and am a rather big Tito Puente fan), I will use my big Altec system for that. The Cornwall system is by far a simpler system and only requires turning on two switches, whereas the big tri-amp system has more switches than I care to count and is a bigger production to fire up (electronic crossover, aural exciter, dc for the turntable, three amps, preamp, you get the picture....). So the much simpler Cornwall system has a definite daily niche use around here and is sounding good to me now (also I am tired of fussing over it for minor reasons really -- since I have ready alternatives when needed). I was glad to see that the old original Type B networks have held up . All that nice 'puddy' is still sticking to the woofer frame and horn and probably does help a tiny bit. Now I like my Corns..... they are what they are..... Could it be a coincidence, maybe these Cornwalls are just now finally "broken in"? Thanks Bob, looking forward to the next Bay get-together. -nm,cxvnm,xcv,mn ¶ nmvbnmbvmn Quote Link to comment Share on other sites More sharing options...
Deang Posted January 20, 2008 Share Posted January 20, 2008 I don't think those are Type B's. I think those networks were designed to be used with an 8 ohm JBL or Altec driver. If you didn't rewire to the correct tap, your midrange is 3dB down from where it should be. Quote Link to comment Share on other sites More sharing options...
Clipped and Shorn Posted January 20, 2008 Author Share Posted January 20, 2008 I don't think those are Type B's. I think those networks were designed to be used with an 8 ohm JBL or Altec driver. If you didn't rewire to the correct tap, you're midrange is 3dB down from where it should be. No one told me about this ahead of time, now it is too late since I have put my Cornwalls back together and it was a project running all those extended wires through the port for the A/B. I just hooked up this new Vcap network to the analogous terminals as if it were a direct sub for the Type B that is in there. You are right the midrange was down a bit and I wasn't sure what that meant at the time other than making me have a better opinion of my old networks. Darn. I think I am going to move on to other projects at this point. -mnbvcxz ≠ zxcvbnm Quote Link to comment Share on other sites More sharing options...
sherwoodhifi Posted January 21, 2008 Share Posted January 21, 2008 Zeno, I moved the mid-range to tap 3 of auto-transformer to match the 16ohm K55 driver before sending the crossover to you. You should be good to go. Bob Quote Link to comment Share on other sites More sharing options...
Clipped and Shorn Posted January 21, 2008 Author Share Posted January 21, 2008 OK, Thanks Bob. I should have known you would have thought ahead on that one. Now I have learned that it is difficult to be objective in one's auditory evaluations. We are so swayed by suggestibility. -091230498 § 980345098435 Quote Link to comment Share on other sites More sharing options...
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