sfogg Posted October 28, 2003 Share Posted October 28, 2003 Did some comparing of squaker drivers tonight. These are measured by TrueRTA at 1/24 octave resolution with an ETF mic and mic pre-amp into a SB Audigy external sound card running at 96/24. The drivers are mounted to a freestanding Altec 511B horn and the mic is about a foot in front of the horn. The attached is a K55V spring clip version. Shawn Quote Link to comment Share on other sites More sharing options...
sfogg Posted October 28, 2003 Author Share Posted October 28, 2003 This is a k55M. Quote Link to comment Share on other sites More sharing options...
sfogg Posted October 28, 2003 Author Share Posted October 28, 2003 K55v again it went missing on the first post. Quote Link to comment Share on other sites More sharing options...
sfogg Posted October 28, 2003 Author Share Posted October 28, 2003 K55v vs. K55M. Quote Link to comment Share on other sites More sharing options...
sfogg Posted October 28, 2003 Author Share Posted October 28, 2003 This is an Altec 902-8B driver. Has a *slightly* better top end response. Anyone else thinking two way La Scala? Shawn Quote Link to comment Share on other sites More sharing options...
sfogg Posted October 28, 2003 Author Share Posted October 28, 2003 K55M vs 902-8B. I forgot to mention that in all of these the drivers are being run full range with no crossover fed from a pink noise source. Shawn Quote Link to comment Share on other sites More sharing options...
sfogg Posted October 28, 2003 Author Share Posted October 28, 2003 The attached is a zip file containing the exported data files for the three drivers. Shawn data.zip Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted October 29, 2003 Share Posted October 29, 2003 Shawn, What horn was used to take the plots? I am assuming it was the Altec 511b. Right? I suspect that the K55V driver you tested is the one with the spring loaded push-pin connections. That's the early one with the one-piece phase plug. Note the glitch at 9 KHz. The later K55V with the solder connections has that glitch worked out of it. It is one of the things that makes the speaker shound harsh. Shawn is sending me one of his 902 drivers. I will be doing more frequency response testing on an Altec 811b horn in the next couple days. I'll be doing impedance plots of it too. Al K. BTW. The high frequency response of the Altec 802 makes my JBL 2426h look silly! Quote Link to comment Share on other sites More sharing options...
BerndH Posted October 29, 2003 Share Posted October 29, 2003 What? Is the K-55M in the range from 400 to 6000Hz about 5dB louder than the K-55V? Can you or anybody else explain these plots? Bernd Quote Link to comment Share on other sites More sharing options...
sfogg Posted October 29, 2003 Author Share Posted October 29, 2003 Al, Yup, that was a spring clip K55V and all drivers were mounted to a 511B. In the case of the K55s I used one of the mounting adapters from Parts Express. Shawn Quote Link to comment Share on other sites More sharing options...
sfogg Posted October 29, 2003 Author Share Posted October 29, 2003 Bernd, " Is the K-55M in the range from 400 to 6000Hz about 5dB louder than the K-55V?" No, they weren't fed exactly the same level between plots. I was adjusting the levels for each measurement such that when I do the overlays of two drivers you can see most of the data for each driver. Shawn Quote Link to comment Share on other sites More sharing options...
BerndH Posted October 29, 2003 Share Posted October 29, 2003 This looks like a 3500Hz crossover point between K-55M and tweeter would be better. What say the experts? Bernd Quote Link to comment Share on other sites More sharing options...
JohnA Posted October 29, 2003 Share Posted October 29, 2003 Shawn, Superb! I have some 902-8Bs and 511Bs, but haven't designed a crossover for them to make 2-way La Scalas, yet! How does the efficiency of the 902 differ from the K-55-V on the 511B? Quote Link to comment Share on other sites More sharing options...
sfogg Posted October 29, 2003 Author Share Posted October 29, 2003 John, "to make 2-way La Scalas" It does look like it should be possible with the Altec driver/horn combo. Any thoughts on mounting the 511b yet? If it does work out as a two way I am almost considering cutting the face of the La Scala to flush mount the 511b to it. The mounting plate on the 511b is almost the perfect size to do that on the La Scala. For my more beat up center channel La Scala that wouldn't bother me as much (and it would help clear the screen) but for my L/R pair (which is just about mint) that would be a lot harder to do. For them I may just leave it on top of the cabinet. "How does the efficiency of the 902 differ from the K-55-V on the 511B?" I haven't really measured it yet but it seems more effecient. When I replaced the K55v with the 902-8B on my La Scalas with ALKs I first measured the SPL with a 1kHz test tone with the K55v set at 4-x. Then I put on the 902-8B. To have just about the same SPL at 1kHz took a setting of 2-0. Of course the K55v is 16ish ohm while the 902-8b is 8ish ohms. Shawn Quote Link to comment Share on other sites More sharing options...
sfogg Posted October 29, 2003 Author Share Posted October 29, 2003 Bernd, "This looks like a 3500Hz crossover point between K-55M and tweeter would be better." That would of course depend on the tweeter used and how successful the blend between the two were done in the crossover. The K55M looks a little better suited to the 6k crossover point then the K55v. The K55v has a pretty big suckout from around 4200 up to 6k compared against the K55M. At least the spring clip K55v does, the solder terminal version is supposed to be improved in this area but I don't have one of those to test. I wonder what the K55x is like? Shawn Quote Link to comment Share on other sites More sharing options...
ZAKO Posted October 29, 2003 Share Posted October 29, 2003 WOW look like the K55M & K55V take a fast nose dive at 6k alot faster than I thought. I cross over at 3.2k With a different tweet. ( SOME TIMES 4k) Quote Link to comment Share on other sites More sharing options...
johnnyp Posted October 29, 2003 Share Posted October 29, 2003 Keep in mind that the frequency plots posted were of the K-55 variations mounted to an Altec 511b horn lens, not a K-400/401. Does not this driver/horn combo require an adaptor? It was interesting, however, to note that the 9khz "bump" remains in this combo too. Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted October 29, 2003 Share Posted October 29, 2003 Guys, NO.. Don't move the crossover down. A lot of T-35s do not have good response below 6000. The fast roll-off of the k55 above 6000 is part of the Klipsch network operation. It IS half of the squawker / tweeter crossover! Klipsch depends on it pooping out at 6 KHz to transition away from the K55 to the T-35 at 6000 Hz. To move the tweeter filter will casue an overlap or a hole! Al K Quote Link to comment Share on other sites More sharing options...
ZAKO Posted October 29, 2003 Share Posted October 29, 2003 Mass roll off.s never did sound good to me. Quote Link to comment Share on other sites More sharing options...
WMcD Posted October 29, 2003 Share Posted October 29, 2003 This data could account for a lot of things. One issue is that we're not seeing all variety of the drivers and not on a K-400. None the less, a fair inference is that the midrange drivers and a horn combination have significant output above 6000 Hz. That may be the problem. This is the nominal crossover frequency of the Klipsch midrange in the Heritage design. The midrange crossovers, are only high pass, not band pass. The theory is that we let the midrange go as high as possible and assume there is no need for a network which cuts off anything above. The assumption is that there is great attenuation by the driver itself above 6 kHz. That may not be the case, as the data shows. The Heyster review of the K-Horn opined that there was a problem with the mid to tweeter crossover point. He didn't say that it was because the mid was still working, but perhaps it was his thought, and may be so in fact. One theory has been that harshness in the K-Horn was the result of a peak (perhaps narrow) above 6000 Hz in the Atlas driver. A solution was the P-Trap circuit. It would short out the midrange driver over some probably narrow passband. It was my understanding that only the Altas needed it. The Vacuum Tube Valley article on the K-Horn suggests the P-trap, but does not limit it to any one driver family. I wondered why. The data shown indicates the problem is not a simple peak. Rather, there is some midrange output (if ragged) over the entire range of the tweeter! It seems more than a Zobel like the P-trap can handle. The crossover for the 2002+ K-Horn is supposed to be very complex. One suspicion is that they've switched over to a bandpass for the midrange. Modern simulation programs would make this more predictable to design. Best, Gil Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.