Didn't You read what I wrote? Ain't a bump-free f3 of 28 Hz good enough?Originally Posted by Lee in Montreal
ruediger
Didn't You read what I wrote? Ain't a bump-free f3 of 28 Hz good enough?
ruediger
yes I read it. Your proposition assumed I was putting the 8 Ohms drivers in serie and ended up with 16 Ohms. Which I will not. Each driver will have its onw channel. One power amp per cabinet. 10cft is in the upper limit of the 2226 recommendation. Because of the horn that amplifies acoustically the mids from, say 100Hz and up, to get a flatter response, the bass portion must be emphasized. Hence that need for a 5db bump with the cabinet tuned to 40Hz.
Here are four bass reflex alignments of a pair of 2226 8 Ohm drivers in the 20cft 4550.
35Hz, 40Hz, 45Hz (2 ports blocked), 65Hz (all ports open). This is assuming the ports are 7"x8" (equivalent roughly to a round Ø8.5 port).
35Hz and 40Hz
45Hz and 65Hz
Spotting the difference between four open ports, or blocking two, one can see that you get 12db more at 40Hz when blocking two ports. But 7db less at 70Hz. Pick your sound.
The vents on my 4550A's are 5.375" X 6.750". They are internally flush with or bounded by the outside wall of the cabinet and closely bounded the horn flare about 3" deep on the inside. I'm not sure how close you will get by calculation if using the front panel thickness of 0.750" as the vent depth.
Hopefully I can take some large signal impedance, magnitude and phase measurements this weekend.
If we knew what the hell we were doing, we wouldn't call it research would we.
Thanks for the measurement. I will ssume a square port of this dimension with 0.75" length. ;-) That should be similar to a round 6.8" port with 0.75" length. Port tuning shall be 58.5Hz with all ports open, and 41.4Hz if blocking two ports. 50.5Hz using three ports. Obviously those are theorical values that can differ from a software to another.
2 ports (41Hz - red line) versus 4 ports (58Hz - blue line). With 2226 drivers, 4 ports seem to work quite well for all out SPL
... whether You feed the two drivers separately from their own amplifier channels or if You bridge the amp and feed the serially connected drivers from the bridged amp.
The proceeding which I suggested would in the 1st step result in a proper alignment. In the 2nd step one could add any boost or whatever is needed.
ruediger
And yes, You need an end correction
All this sciency stuff makes way more sense to me now than it did in '75 when I traded a set of EV Eliminators I got for a song not long before and matching high horns a for a pair of two (or three) year old 4550s and 2350s (with "Earthquake" still in everyone's memory) . They came from a school auditorium whose new art director had decided that the unresponsive JBL PA system sounded WAY too "dark" for his taste FFS. He was switching to the brilliance of an all EV system - good for me!
When I went to my next job with very high expectations, replacing a quad of A7s and mix of EV and Peavey stuff for front sound with just my first pair of 4550s and some K140 and K120 mid boxes, two 2350s and (I used all the 511s, too, though) all the Crowns and Phase Linears I could scrounge, I was barely able to contain my drool! However, I think I lost a little pee once I had it all set up right.I was extremely pleased with what punchy and usable deep sounds I was hearring. All four were loaded with 2220s, very efficient compared to what I had been using!
I worked at a music store and found a way to get the other pair of 4550s the following week. No, I had only a single 1/3 octave EQ an no analyzer at the time, but using just the boards controls, I got some of the best sound I had ever heard up to that time!
I used those same four awesome cabinets for another two years, before the continued onward and upward need for more power forced me to replace them.
.. .. ... but I should have kept them for today!!!
I saw this on ebay ... NOW do not misunderstand! I do not know this guy, nor do I care about his sale, but when I saw these walnut veneered 4550s, I just about, well you may know. I HAD to share this imagery with all here.
No implication from me about this seller, other than a drool factor !! This pair just happen to have consecutive serial numbers as well!!
Those are a lot prettier than mine!
As a note, I have 2220's in two of mine and I agree, they sound the best, you just can't be mean to them.
If we knew what the hell we were doing, we wouldn't call it research would we.
So. Did you yet tried the 2226 woofers in the 4550s ?
I did, and it was good! Monday I bought a dozen more to load the rest of them so I finally get to play all 10 of them together with all 2226's.
If we knew what the hell we were doing, we wouldn't call it research would we.
I's going to be impressive. I've been running 2226s for only a month now and am learning about how to set them. They have a good kick that the 2225 doesn't have. I use a 12bd low pass filter at 120Hz with 9db boost to get a fat bass without too much mid and crossed them at 450Hz. You definitely need to push the bottom of those drivers and they can take it (or skim the excess mids).
Did you say TEN 4550`s?I did, and it was good! Monday I bought a dozen more to load the rest of them so I finally get to play all 10 of them together with all 2226's.
Good God, so .. you are ready to populate a full ten of 4550s?I did, and it was good! Monday I bought a dozen more to load the rest of them so I finally get to play all 10 of them together with all 2226's.
... with a decent LF driver?
I wish I was there!
Yeah it's going to be fun. We have to be in contention for the craziest shop stereo in town. They are currently loaded with 2227's and 2220's.
I know, I know,,, it's a sickness.
If we knew what the hell we were doing, we wouldn't call it research would we.
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