first equipment:
Fe83en with OB that is 85 by 35 cm. Suspended by wire from the ceiling.
Harmon Kardon avr 125
Focusrite 2i2
Behinger ECM8000
REW software
The results taken from 6 inches from driver 1/24 octave smoothing:
Looks about right? The left speaker which is green has had the dust cap pushed in by my 2 year old. I figure that is why the HF roll off is different. I figure any below 60 hz is just noisy.
Fe83en with OB that is 85 by 35 cm. Suspended by wire from the ceiling.
Harmon Kardon avr 125
Focusrite 2i2
Behinger ECM8000
REW software
The results taken from 6 inches from driver 1/24 octave smoothing:
An externally hosted image should be here but it was not working when we last tested it.
Looks about right? The left speaker which is green has had the dust cap pushed in by my 2 year old. I figure that is why the HF roll off is different. I figure any below 60 hz is just noisy.
That's interesting, especially for a guy intrigued by single driver set-ups (realizing however, that would need something for the bottom end...)and OB's. What do you suppose is causing that dip at 2.5 KHz? How noticeable would that be? Maybe doing something with the dust cap on the other one would help; it looks like a 5dB difference in the dip.
Thanks,
Mike
Thanks,
Mike
I think the dip at 2.5khz is normal considering what the fostex spec's with the Fe83en. I believe it shows a 10 db dip at 2.5k.
I am going to get the dust cap repaired... sometime...
I am going to get the dust cap repaired... sometime...
Funny I was just thinking about these little driver's the other day. I was thinking about putting together a project for a friend's as a gift? I will ponder the idea first before I go ahead and spend the time and money into this idea? Good luck hope your (O.B.) idea works out. Mr. Daniel
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The dip at 2.5khz is the driver. Further out it measures even worse, at least it did for me. 6" measurements aren't to useful at those frequencies. And at that distance you aren't fully capturing the OB.
There's a lot of problems with a setup like this. Are you aware? Do you plan on using woofer support?
There's a lot of problems with a setup like this. Are you aware? Do you plan on using woofer support?
I was planning on having 6 inches being a base line.
I am not aware what the problems are with this setup, can you please help correct my errors.
I want to get the best freq. Response as possible with the fe83en's because I have it.
If you want the best FR possible with that driver, then mount it in an infinite baffle. This is impractical usually though. So I'd say a closed baffle box in the form you can enjoy. Whether ported or sealed. Either way, speaking from experience, this driver does bass very poorly. But it's what you have so. Just consider adding woofer support down the road. I think you could use it.
The problems are dipole peak, and bass roll off. With an OB that size, there's a frequency (off the top of my head, probably 500hz) where a peak in the response will form, and off axis that peak will change requency. OB builders avoid this peak like the plague. I personally don't have experience with it, other than some basic reading on the subject. But I know it's something to be avoided. The bass roll off below the dipole peak will be substantial. You'll have poor power handling, low sensitivity, and a very inaccurate FR.
OB really deserves a multi-way configuration to make it work right (avoid the dipole peak and bolster the low frequency losses).
Your 6" measurement will provide you with somewhat of a baseline, but not totally. Nearfields aren't that useful for high frequencies. The best baseline is an IB measurement with a nearfield or ground plane for less than 200hz. But that's a lot of work. This would give you it's response without any baffle and box type/size influence.
The problems are dipole peak, and bass roll off. With an OB that size, there's a frequency (off the top of my head, probably 500hz) where a peak in the response will form, and off axis that peak will change requency. OB builders avoid this peak like the plague. I personally don't have experience with it, other than some basic reading on the subject. But I know it's something to be avoided. The bass roll off below the dipole peak will be substantial. You'll have poor power handling, low sensitivity, and a very inaccurate FR.
OB really deserves a multi-way configuration to make it work right (avoid the dipole peak and bolster the low frequency losses).
Your 6" measurement will provide you with somewhat of a baseline, but not totally. Nearfields aren't that useful for high frequencies. The best baseline is an IB measurement with a nearfield or ground plane for less than 200hz. But that's a lot of work. This would give you it's response without any baffle and box type/size influence.
A few random thoughts:
As Ryan notes, the dip is "built-into" the driver's response - even shows in Fostex's often generously smoothed published graphs, and it's almost to be expected to find differences between stock and damaged drivers when measured at that close a distance.
Even the most nearfield situation in which I've ever used drivers in this size range myself places them at least 18 -24" out.
Judicious digitial EQ could possibly mitigate the 2.5K dip, but that could be the least of the issues, depending on intended application.
I've only heard the FE83 in a small vented enclosure, played without woofer support, in a moderate sized room ( 300ft^2?), and would have to agree with Ryan's assessment of its real world bass performance. If your plan is to add woofers, then that's probably moot. If not, then a BR or small MLTL would likely get you the most bandwidth - not without the penalty of reducing maximum attainable SPLs - but not to the same degree as running crossed over too low on a small OB .
Depending on the degree of damage to the dust cap, if repair is not completely satisfactory, then you can always carefully circumcise them and add small phase plugs.
As Ryan notes, the dip is "built-into" the driver's response - even shows in Fostex's often generously smoothed published graphs, and it's almost to be expected to find differences between stock and damaged drivers when measured at that close a distance.
Even the most nearfield situation in which I've ever used drivers in this size range myself places them at least 18 -24" out.
Judicious digitial EQ could possibly mitigate the 2.5K dip, but that could be the least of the issues, depending on intended application.
I've only heard the FE83 in a small vented enclosure, played without woofer support, in a moderate sized room ( 300ft^2?), and would have to agree with Ryan's assessment of its real world bass performance. If your plan is to add woofers, then that's probably moot. If not, then a BR or small MLTL would likely get you the most bandwidth - not without the penalty of reducing maximum attainable SPLs - but not to the same degree as running crossed over too low on a small OB .
Depending on the degree of damage to the dust cap, if repair is not completely satisfactory, then you can always carefully circumcise them and add small phase plugs.
To be honest I bought the fe83en and L6-6r drivers when I had no idea what I was doing. I made the OB when I still knew nothing and I am trying to learn something from my actions.
So I have some corrections to make and additional info:
The amp is a harmon karon avr 145 not 125.
OB is 85 cm by 37.5 cm.
Driver position is 47.5 cm y-axis (from bottom), and 8.5 cm x-axis (from left side).
Room size: 44.63 square metres (480.43 square feet) See below.
Yay MS paint!, rest of surfaces are uncovered poured concrete
Meaningful measurements will be posted soon! (ie. 24" from baffle)
So I have some corrections to make and additional info:
The amp is a harmon karon avr 145 not 125.
OB is 85 cm by 37.5 cm.
Driver position is 47.5 cm y-axis (from bottom), and 8.5 cm x-axis (from left side).
Room size: 44.63 square metres (480.43 square feet) See below.
Yay MS paint!, rest of surfaces are uncovered poured concrete
Meaningful measurements will be posted soon! (ie. 24" from baffle)
An externally hosted image should be here but it was not working when we last tested it.
I think you're gonna want something substantially beefier to fill a room that size to even modest levels, and certainly if looking for any degree of LF response, at least a pair of 6-8" woofers if sealed or vented, or larger if OB.
There appears to be more than adequate floor space for OB if that's your intention, but be aware that you'd want to XO to the FE83s at well into the mid several hundreds ( 300-400Hz?) to attain reasonable SPL levels ( mid 90s at peak).
With a receiver such as the AVR 145 that lacks line level outputs for any of the 5 main & surround channels, implementing active bi-amping is a bit tricky. As has been noted above, while any XO frequency can be attained at speaker level, in the mid hundreds of HZ, the cost of passive components can quickly surpass that of the small FR drivers themselves, and require careful selection of drivers with appropriate sensitivities.
I'd be inclined to a small vented enclosure of some sort for the FE83s ( a conventional BR could be pretty tiny ), set the speaker size to small on the AVR145, and cross them over to the LFE channel as high as it will allow.
There appears to be more than adequate floor space for OB if that's your intention, but be aware that you'd want to XO to the FE83s at well into the mid several hundreds ( 300-400Hz?) to attain reasonable SPL levels ( mid 90s at peak).
With a receiver such as the AVR 145 that lacks line level outputs for any of the 5 main & surround channels, implementing active bi-amping is a bit tricky. As has been noted above, while any XO frequency can be attained at speaker level, in the mid hundreds of HZ, the cost of passive components can quickly surpass that of the small FR drivers themselves, and require careful selection of drivers with appropriate sensitivities.
I'd be inclined to a small vented enclosure of some sort for the FE83s ( a conventional BR could be pretty tiny ), set the speaker size to small on the AVR145, and cross them over to the LFE channel as high as it will allow.
More Measurements!
Below at 30 inches
Now at 75 inches (listening position)
Combined!
Below at 30 inches
An externally hosted image should be here but it was not working when we last tested it.
Now at 75 inches (listening position)
An externally hosted image should be here but it was not working when we last tested it.
Combined!
An externally hosted image should be here but it was not working when we last tested it.
The farther away you get, the more room interaction you get. You want to get as close as possible and still preserve the OB roll-off. You will know when you enter the nearfield.
Bob
Bob
Sorry I hate to double post but I have sometime now.
To Tuxedocivic and Chris,
I am not ignoring your posts, they are quite informative. I quite agree that fe83en is best in a BR. I have just grown quite fond of the OB sound. I do not like putting down how it sounds, because none of you can hear it! I prefer quantitative measurements so we may objectively look at the overall speaker design.
That being said I may throw my two L6-6r's in a separate OB or enclosure depending on wood supply and use the line level sub out into my heathkit AA-23 and play around with it. I want a separate OB as to make mistakes on 🙂
To Bob,
To my understanding 30 inches to nearfield. I use this distance for recording and thought it would be a natural place to start. As for my listening position, it is at 75 inches, because my lawn chair fits there!
This being said, I am new to this and I do hope this is helpful to other newbie's.
To Tuxedocivic and Chris,
I am not ignoring your posts, they are quite informative. I quite agree that fe83en is best in a BR. I have just grown quite fond of the OB sound. I do not like putting down how it sounds, because none of you can hear it! I prefer quantitative measurements so we may objectively look at the overall speaker design.
That being said I may throw my two L6-6r's in a separate OB or enclosure depending on wood supply and use the line level sub out into my heathkit AA-23 and play around with it. I want a separate OB as to make mistakes on 🙂
To Bob,
To my understanding 30 inches to nearfield. I use this distance for recording and thought it would be a natural place to start. As for my listening position, it is at 75 inches, because my lawn chair fits there!
This being said, I am new to this and I do hope this is helpful to other newbie's.
Well, I'd say your 30" measurement is fairly representative. There's some reflections but I can smooth them with my eye. I can see that 2.2khz issue. It's nasty. I hear it easily on Diana Krall's voice. Very nasal sounding.
Well, there you have it, the objective data says you have an F3 of ~220hz. I can't hear your speakers, true, but I can objectively say that must sound very lean, lacking, shouty, SPL limited, etc. Not putting it down, I'm suggesting as much as you may like this sound, it can be improved. I know this based on my experience with this driver. Not just an arm chair critic here. If you're interested in what I think would be an improvement, I'd seal it up.
Well, there you have it, the objective data says you have an F3 of ~220hz. I can't hear your speakers, true, but I can objectively say that must sound very lean, lacking, shouty, SPL limited, etc. Not putting it down, I'm suggesting as much as you may like this sound, it can be improved. I know this based on my experience with this driver. Not just an arm chair critic here. If you're interested in what I think would be an improvement, I'd seal it up.
No offence is taken. I want constructive criticism! So I am taking note that this is not how to build a OB speaker!
I am looking into walling in my area and treating the room.
As well, I have some ideas for modifications and will post with results.
I am looking into walling in my area and treating the room.
As well, I have some ideas for modifications and will post with results.
There is nothing wrong with a 220 Hz low end on the fullrange portion which is OB if you help it out with a woofer crossed at about same point. Woofer does not need to be OB. Sealed works well.
Guys, the FE83En in an OB or sealed is definitely going to sound nasal. This is not the direction to go with this driver IMO. You need a well tuned BR to get any body to the sound out of this driver. And proximity to walls helps for further reinforcement.
Do these drivers have any significant hours on them?
In the right width baffle, the FR anomolies get mostly worked out via baffle step once its in a proper cabinet.
Best,
Clark
Do these drivers have any significant hours on them?
In the right width baffle, the FR anomolies get mostly worked out via baffle step once its in a proper cabinet.
Best,
Clark
excellent advice from Clark - he has a very decent sounding and successful commercial product using this driver
Orca Fullrange ? Blumenstein Audio
Orca Fullrange ? Blumenstein Audio
An externally hosted image should be here but it was not working when we last tested it.
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