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Lee in Montreal
12-13-2012, 07:14 PM
I am wondering if anyone knows the volume of the JBL 4550, minus the horn obviously. ;-)

1audiohack
12-13-2012, 09:26 PM
Roughly 21 cubic feet.

Lee in Montreal
12-14-2012, 05:39 AM
Thanks very much. So, at 10cf per driver, that cabinet has the potential to go low with the proper port tuning and right drivers (2235 - 2234). There will be more midrange than lower bass because of the horn loading, but that's nothing that can't be equalized for hifi duty I guess.

I am asking as I have been offered a pair. Not original but nicely crafted from high quaity Russian ply and all the proper bracing.

Lee in Montreal
12-16-2012, 09:00 AM
So, Barry, what driver do you think would work best for home duty? 2234 or 2235? I know you are fitting 2227 in yours, but I wish to go a bit lower than the 2227's Fs of 40Hz

Ruediger
12-16-2012, 11:29 AM
Hi Lee,

I checked 2225, 2226, E130, E140, none of them matches.

Have a look at formula 70 in the Thiele paper. 1/Qt = 1/Qa + 1/Qe [Re / (Rg + Re) ]

I calculated for the 2225H what happens when You connect two of them in series.

Re is the DC resistance of the voice coil, and Rg is the amplifier's output impedance plus losses in cable and in xover. Assume Rg was zero (thick amp, thick cables, no passive xover).

If You connect two drivers in series, then each of them will see the other driver's Re as its effective Rg.

1/Qt = 1/2.5 + 1/0.31 [ 6.3 / (6.3 + 6.3)]

This gives You a new (higher) Qt, thus an entry in Thiele's table (requires some interpolation) and a new f3.

Do the calculations Yourself.

Ruediger

Lee in Montreal
12-16-2012, 12:10 PM
Hi Ruedigger. I mentionned the 2234 and 2235 for better low end at the expense of all out "loudness". ;-) 10cft is indeed too much volume for a 2225, and even worst for a 2226.

Ruediger
12-16-2012, 12:18 PM
... 10cft is indeed too much volume for a 2225, and even worst for a 2226...

For a stock 2225 yes, but if two are connected in series, it fits. Do the calculations and check the table.

Calculating the new Qt gives a value of 0.5 This is quite the middle between entries 7 and 8 in the table.

f3 = fs * 0.7, which is 28 Hz. Low enough?

Vb = Vas / 0.645 = 273 ltr, which is ca. 10 cu ft.

2226 has very similar params as 2225.

Ruediger

1audiohack
12-17-2012, 10:45 AM
Hello Lee;

I have not spent any real time with these yet. I have four of them loaded with 2227's and two with E130's. I am listening to the ones loaded with 2227's as the shop stereo and am not delighted with the low end. Now out of fairness, they are replacing six 2242's for he bottom. Since they're not horn loaded below about 120-140Hz I too think drivers possessing either a lower corner and or less rising response will sound fuller. I have 2226's for two of them and 2220's for the other two but have yet to load them.

Hi Rudiger;

I haven't done anything but an ETC and quick EQ on these so I, as always, appreciate your input as well.


Thank you and all the best,
Barry.

Eaulive
12-29-2012, 12:24 PM
So Lee, the 4520's were not big enough? :D

Lee in Montreal
12-29-2012, 01:14 PM
The 4550 are indeed 25% bigger than 4520, I agree, but I am now only looking for another type of sound and bass articulation. It is part of a life long quest in sound... :bouncy:

Lee in Montreal
01-24-2013, 06:01 PM
So, I have this party coming in February. The place is quite big and can host 250 people but I don'T expect more than 80 people on the dancefloor all at once. The occasion of that party is to celebrate a bar that was in operation in 1980-84. A friend will loan his set of empty 4550s, while I will bring my 4520 for extra bass. On top of the 4550s, I will use my 2350s with 2441 drivver and some 2405 on top. I will keep the 4520s loaded with my 2225. I was thinking using four 2226 in the 4550 for basically two reasons. The 4550 is bass reflex cabinet which suits a bass reflex driver (the 2226). That driver doesn't go as low as the 2225 and it's fine as the 4550 doesn't go as low either. The 4550 will be used mostly for midbass and lower medium. That'S where I think the 2226 shines. Crossed over around 600Hs and no higher than 800Hz.

With 10cft per driver, if the bass reflex is tuned to 40Hz, then I get a 5db bump at 40Hz that compemsates for the horns' midrange bump of around 5db from 100Hz up. I can have a relatively flat curve.

HAs anyone tried that combo? 4550 + 2226? Barry?

1audiohack
01-24-2013, 10:34 PM
Hi Lee;

I've put a few of drivers through mine, E130's, 2220's, 2226's, and 2227's. The best bottom is the 2226's, no surprise I know. They are a good fit so I just got six more 2226's to double stack each side.

My best results were with a full 2kW across each pair of drivers with a 30Hz 12dB high-pass. They sound good to 800Hz, no issue.

How many4550's will you have? Two or four?

Lee in Montreal
01-25-2013, 12:46 AM
I will only have two 4550. One per side. Bass reflex cabinet + 2226 should indeed be a good match. I wonder to which frequency the cabinet's bass reflex is tuned. Did you have to use spacers between the woofer and the mounting flange? Also, I was planning a 24db HP filter at 30Hz.

BTW Can you measure the size of the 4 ports on the front? That shall tell me to which frequency the ports are tuned. If they are 7 x 8, then with all 4 ports opened, that should give around 66Hz. Block two and you get 46Hz. Calculated for a volume of 20cft

ivica
01-25-2013, 03:15 AM
So, I have this party coming in February. ......
.......... On top of the 4550s, I will use my 2350s with 2441 drivver and some 2405 on top...................?

Hi Lee,

Pay Your attention at 2441 (if Aluminum diaphragms in them) not to destroy AL:eek:

1audiohack
01-25-2013, 06:11 AM
Hi Lee;

I am going to load four more of mine with 2226's this weekend and re-stack. I will take the VI box and take some impedance measurements.

Ruediger
01-25-2013, 06:17 AM
With 10cft per driver, if the bass reflex is tuned to 40Hz, then I get a 5db bump at 40Hz that compemsates for the horns' midrange bump of around 5db from 100Hz up. I can have a relatively flat curve.



Didn't You read what I wrote? Ain't a bump-free f3 of 28 Hz good enough?

ruediger

Lee in Montreal
01-25-2013, 06:24 AM
Didn't You read what I wrote? Ain't a bump-free f3 of 28 Hz good enough?

ruedigeryes 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.

Lee in Montreal
01-25-2013, 07:27 AM
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 8.5 port).

35Hz and 40Hz
58050

45Hz and 65Hz
58051

Lee in Montreal
01-25-2013, 08:00 AM
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.

1audiohack
01-25-2013, 08:24 AM
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.

Lee in Montreal
01-25-2013, 08:27 AM
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. 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

58058

Ruediger
01-25-2013, 01:06 PM
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.

... 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

BeDome
04-17-2013, 10:08 PM
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. :jawdrop: 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!!

58723

58725

1audiohack
04-17-2013, 10:15 PM
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.

Lee in Montreal
04-18-2013, 05:24 AM
So. Did you yet tried the 2226 woofers in the 4550s ?:bouncy:

1audiohack
04-18-2013, 07:07 AM
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. :D

Lee in Montreal
04-18-2013, 07:17 AM
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).

Mike F
04-18-2013, 06:59 PM
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. :D
Did you say TEN 4550`s?

BeDome
04-18-2013, 07:08 PM
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. :D

Good God, so .. you are ready to populate a full ten of 4550s?

... with a decent LF driver?

I wish I was there!

1audiohack
04-18-2013, 11:13 PM
Good God, so .. you are ready to populate a full ten of 4550s?

... 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.

BeDome
04-20-2013, 04:30 AM
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.

As I said before, I may lose massive amounts of presumably secure bodily fluids at the mere thought of huge stacks of 4550s, let alone the reality of such.

I am in AWE!

I do not think of your "troubles" as much of a sickness but rather a a treasure trove.

BeDome
04-20-2013, 04:42 AM
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.


Agreed, but it would be kind of hard to be mean to a quad of 2220s with a pair of DC300 Crowns. LoL