F1 FAN said:The Vifa looks like a great choice for a mid,I would be very surprised if you don't get much better results from it.That Solen On sale page is great
I'm counting on it.
The sale is for 4 of these. Hopefully I can get 2.
I'm also considering getting 8 more of the SesCA21REX to build two matching subs for these speakers.
> This is the basis for my belief the response is peaked (maybe around 1K).
Hm, hard to tell without actual measurements... but peaks in this region really get on the nerves...
Lucky for you a closed box midrange is a lot easier to replace than a bass-reflex woofer (I still have some failed boxes around, lol)
Hm, hard to tell without actual measurements... but peaks in this region really get on the nerves...
Lucky for you a closed box midrange is a lot easier to replace than a bass-reflex woofer (I still have some failed boxes around, lol)
peufeu said:
I will try to get some measurements up here (I'm at my HTPC where the speakers live). I have the mic + preamp + Wallin jig mostly operational. I'll use the active amp as the test signal amp. Might get a rudimentary idea of what's going on.
It could take some time...
peufeu said:
I'm also lucky for the perfect fit of the replacement.
I was able to get some measurements. These are not the most accurate, as nothing is calibrated up here, but they do show some things fairly consistently. There is a peak at about 750hz and another peak at 1600hz and, I was wrong, there is a dip at 1K. I guess it's the combination of the three that's the problem.
There were 2 sets of measurements taken. The first at about 1 metre on axis and the second, at a lower volume, at about 20cm on axis. This was done with the signal going just to the midrange under test, the slide pots for the other drivers were at zero.
The graphs below are the results. There are 3 consecutive tests superimposed on each other. Blue is frequency response and red is phase response.
Charts are 1/6 octave smoothed.
There were 2 sets of measurements taken. The first at about 1 metre on axis and the second, at a lower volume, at about 20cm on axis. This was done with the signal going just to the midrange under test, the slide pots for the other drivers were at zero.
The graphs below are the results. There are 3 consecutive tests superimposed on each other. Blue is frequency response and red is phase response.
Charts are 1/6 octave smoothed.
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peufeu said:
Yeah, there's two ways of seeing it: peaks at 750 and 1600 or one big dip at 1K. I can't see that being attributable to the box.
Consider another frequency response test I did here. This was a Vifa PL18 in a sealed empty box.
Granted, the test setup was a little more professional there but we get a general idea.
Just for the heck of it, I ran the test again through the equalizer. My settings on that that made it sound close to normal (adjusting by ear) was cutting the 750 peak way down. Further adjusting cut the 1600hz peak also. The results are much better, but it still doesn't sound completely right.
I'm just going to go ahead and order those drivers and chalk this one up to experience.
I've been looking around for other possibilities, in case I can't get the P11's.
Not on sale, but it most likely is a much better driver: Vifa PL11MH09-08. This is also the right size and has ruler flat response from 300 to 3K. Reasonably efficient at 87db, it is a dedicated midrange and I think it would be a good fit.
I think I'll get these anyway.
Not on sale, but it most likely is a much better driver: Vifa PL11MH09-08. This is also the right size and has ruler flat response from 300 to 3K. Reasonably efficient at 87db, it is a dedicated midrange and I think it would be a good fit.
I think I'll get these anyway.
They look even better and I think treated paper cones are better than poly for midrange use.Here is another possibility http://www.seas.no/images/stories/prestige/pdfdatasheet/h1304_mca12rc_datasheet.pdfMJL21193 said:I've been looking around for other possibilities, in case I can't get the P11's.
Not on sale, but it most likely is a much better driver: Vifa PL11MH09-08. This is also the right size and has ruler flat response from 300 to 3K. Reasonably efficient at 87db, it is a dedicated midrange and I think it would be a good fit.
I think I'll get these anyway.
Today, I set up my Speaker Workshop test gear properly and ran a few tests. The results from last night were too rough, and I'm not happy with only half of the information.
I did a series of near field tests. First on the midrange. The test was taken with the driver still in the cabinet and the mic 1/2" from the tip of the phase plug. The tests were repeated several times. I increased the sample size in SW to 132K and set the repeat count to 3. Sample rate is 48K.
Here is how it looks. This is the results of 4 consecutive tests, superimposed on top of each other. This is not as bad as last night, but still, it's quite evident there's a problem with this driver in the 1k to 1.2k area of response.
I did a series of near field tests. First on the midrange. The test was taken with the driver still in the cabinet and the mic 1/2" from the tip of the phase plug. The tests were repeated several times. I increased the sample size in SW to 132K and set the repeat count to 3. Sample rate is 48K.
Here is how it looks. This is the results of 4 consecutive tests, superimposed on top of each other. This is not as bad as last night, but still, it's quite evident there's a problem with this driver in the 1k to 1.2k area of response.
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peufeu said:Nice wiggle
f = 1000 Hz => wavelength is about 34 cm in air... could this be the roundtrip between the driver and the rear of the box ?
Hi,
The back of the box in that area is less than 20cm, and is covered with the styrofoam wedges to break up standing waves.
I don't think it's a box resonance, but I'll find out for sure when I take out those drivers.
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The last test is with the mic 1 metre from the speaker, aimed between the midrange and woofer. All three drivers are active and I adjusted the slide pots to get a fairly flat response (this was unexpected - I "tuned" these by ear before and that was putting the midrange and tweeter output about 4db higher than the woofer).
Power output is something like this: 100% to the woofer, 50% to the midrange and 55% to the tweeter. With differences in the sensitivity of each driver and the impedance of each one having a big effect.
Power output is something like this: 100% to the woofer, 50% to the midrange and 55% to the tweeter. With differences in the sensitivity of each driver and the impedance of each one having a big effect.
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Today I went ahead and ordered two PL11MH09-08. I know these are better mids and these speakers are worth it IMO.
The lower sensitivity will not be a problem as I have 50% of the amps power in reserve when using the present drivers.
I also ordered a driver for a new centre speaker, the T18RE COAX by Seas. With this I ordered the crossover components using Tony Gee's USB as the example.
Looking forward to starting this with the next few weeks.
The lower sensitivity will not be a problem as I have 50% of the amps power in reserve when using the present drivers.
I also ordered a driver for a new centre speaker, the T18RE COAX by Seas. With this I ordered the crossover components using Tony Gee's USB as the example.
Looking forward to starting this with the next few weeks.
Absolutely.MJL21193 said:
This driver is a wonderful choice for center channel usage.It does not have the lobing problems normally associated with separate woofer /tweeter.Many years ago I built a pair of speakers using SEAS first generation COAX the H489.They soounded good until I killed one with 45 volts of DC.
F1 FAN said:
...until I killed one with 45 volts of DC.
That's too bad, though I feel your pain. I have a stack of different drivers in my lab that have fought (and lost) the battle with DC.
I've learned my lesson: a DC blocking cap on my test speaker now.
I was considering using this driver in a sealed box, but looking at it in Unibox, I don't think I'd be happy with the outcome. I will most likely just copy Tony's alignment, using the same port size.
I got my new mids today and I'm getting ready to put them in. The mounting flange is a bit thicker on the new ones, so I'll need to cut out the recess a little deeper - some delicate work with the utility knife.
Also, the magnet on the new ones is quite a bit bigger, so some more sculpting of the chamber divider is called for.
Also got the Seas coax for my new centre speaker. I'll be starting the box for that tomorrow and building it in the same style as these. Curved baffle, piano black finish with a stained veneer body.
Also, the magnet on the new ones is quite a bit bigger, so some more sculpting of the chamber divider is called for.
Also got the Seas coax for my new centre speaker. I'll be starting the box for that tomorrow and building it in the same style as these. Curved baffle, piano black finish with a stained veneer body.
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