zobsky said:
I tried that (though I folded the line) , .. wasn't happy with the bass I was getting (though it is possible that I goofed up)
I was happier with a MLTL (similar to Tim Forman's Rosa) using two WR125s drivers per cabinet.
Thanks GM, for your help
Greets!
You're welcome! No, even with only relatively modest stuffing the sim says it's dying fast below 100 Hz, so strictly a midbass alignment unless corner loaded, somewhat wasting all that Xmax.
Yeah, with such a low efficiency, for sure two drivers are required for all but the most 'intimate' (background and/or nearfield) apps IMO. That, or some sort of horn...........
GM
Performance of FR125S/WR125S ML-TL (Part 1)
Earlier in this thread Dave (and perhaps others) reported issues with ML-TL designs that use the FR125S. I have taken a series of measurements on my version of GM's bipole ML-TL design. A complete disclosure of this design is located at:
http://homepage.mac.com/tlinespeakers/FAL/downloads/BipolarMLTLDesignPak.pdf
I have listened to my speakers for a few weeks now and I've tried material with fairly heavy bass (for example, Keb Mo's recording and others) at levels in the 90-100 dB SPL range. I have not heard the speaker bottom out nor a discernable port noise. I decided to take some data to report on the performance of my speakers.
The attached plot is a measurements of the performance of my speaker taken in room (my garage) at a 1 meter distance. This plot shows room effects and likely a bipole dip in the below 600 Hz area. Hence, I would say that you shouldn't assume that this plot represents the true performance of the speaker below 600 Hz. I'll post a near field measurement in the next posting (Part 2) on this site.
This plot does show that the speaker has a flat frequency response (within +/- 3 dB from 600 Hz to 20,000 Hz).
I'll continue in Part 2.
Jim
Earlier in this thread Dave (and perhaps others) reported issues with ML-TL designs that use the FR125S. I have taken a series of measurements on my version of GM's bipole ML-TL design. A complete disclosure of this design is located at:
http://homepage.mac.com/tlinespeakers/FAL/downloads/BipolarMLTLDesignPak.pdf
I have listened to my speakers for a few weeks now and I've tried material with fairly heavy bass (for example, Keb Mo's recording and others) at levels in the 90-100 dB SPL range. I have not heard the speaker bottom out nor a discernable port noise. I decided to take some data to report on the performance of my speakers.
The attached plot is a measurements of the performance of my speaker taken in room (my garage) at a 1 meter distance. This plot shows room effects and likely a bipole dip in the below 600 Hz area. Hence, I would say that you shouldn't assume that this plot represents the true performance of the speaker below 600 Hz. I'll post a near field measurement in the next posting (Part 2) on this site.
This plot does show that the speaker has a flat frequency response (within +/- 3 dB from 600 Hz to 20,000 Hz).
I'll continue in Part 2.
Jim
Attachments
Performance of FR125S/WR125S ML-TL (Part 2)
I next measured the frequency response at a distance of 3 inches. At this distance what is plotted is the bipole performance of the speaker but without the any room effects/reflections. This plot has a practical upper limit for accuracy of about 900 Hz so you can ignore data beyond that point. But within the window below 900 Hz, observe that the performance is outstanding--very flat.
In both plots in Parts 1 and 2 the low end of the band does not include output from the port. You can observed in the near field plot that a small dip (the port and driver outputs are 180 out of phase at this dip) occurs in the lower end rolloff skirt near 40 Hz. The dip in the far field plot occurs just above 30 Hz. The acoustical addition of the port measurement to the near and far field plots would fill this dip and extend the low end 3 dB rolloff lower in frequency than observed in these plots. Note that the phase between the port and driver output varies so they don't necessary add dB wise at all frequencies. For instance, the near field plot rolls off 3 dB or so at 65 Hz but in reality the low end would extend below that point if output from the port was included in the plot. My listening would indicate that these speakers approach GM's calculated 3 dB at 45 Hz.
Once you integrate the data between the far and near field plots as I suggested, the performance of my speakers shows to be very flat over the entire frequency band. I don't see issues in their bass response response with their current length of 40 inches. While others have suggested that the ML-TL line length should be shortened or the port stuffed, I'm not in that camp. I think that this design is near optimum with the current parameters. While room effects and stuffing can be changed and these changes would influence their in-room performance.
Jim
I next measured the frequency response at a distance of 3 inches. At this distance what is plotted is the bipole performance of the speaker but without the any room effects/reflections. This plot has a practical upper limit for accuracy of about 900 Hz so you can ignore data beyond that point. But within the window below 900 Hz, observe that the performance is outstanding--very flat.
In both plots in Parts 1 and 2 the low end of the band does not include output from the port. You can observed in the near field plot that a small dip (the port and driver outputs are 180 out of phase at this dip) occurs in the lower end rolloff skirt near 40 Hz. The dip in the far field plot occurs just above 30 Hz. The acoustical addition of the port measurement to the near and far field plots would fill this dip and extend the low end 3 dB rolloff lower in frequency than observed in these plots. Note that the phase between the port and driver output varies so they don't necessary add dB wise at all frequencies. For instance, the near field plot rolls off 3 dB or so at 65 Hz but in reality the low end would extend below that point if output from the port was included in the plot. My listening would indicate that these speakers approach GM's calculated 3 dB at 45 Hz.
Once you integrate the data between the far and near field plots as I suggested, the performance of my speakers shows to be very flat over the entire frequency band. I don't see issues in their bass response response with their current length of 40 inches. While others have suggested that the ML-TL line length should be shortened or the port stuffed, I'm not in that camp. I think that this design is near optimum with the current parameters. While room effects and stuffing can be changed and these changes would influence their in-room performance.
Jim
Attachments
bottoming the FR125
Jim, my experience differs as far as bottoming these drivers out is concerned: on both the bipole MLTL and Dave's mini-Onken, and with every amp I've tried, there's one track that does it every time at any volume level above 80db.
Patricia Barber: Modern Cool "Post Modern Blues" (the "Bill Gates" lyric is just Ms B being, well, Ms B) AFAIK, this track was not intentionally designed at a torture test, but has certainly proven to be.
This recording does not have the same effect on Fostex FE127 in very similar bipole MLTL configuration. While up to the overload point, the FR125 maintains a clear superiority in terms of low end weight and extension, it never quite catches up to the midrange of the FE127 ; and don't get me started about the FE108E Sigma - but that's another story,
We've somewhat tamed this by stuffing the ports in both the Onkens and MLTLs - I'm not sure that Dave has yet graphed the results, but I'm sure that some fiddling could optimize the aperiodic loading.
Jim, my experience differs as far as bottoming these drivers out is concerned: on both the bipole MLTL and Dave's mini-Onken, and with every amp I've tried, there's one track that does it every time at any volume level above 80db.
Patricia Barber: Modern Cool "Post Modern Blues" (the "Bill Gates" lyric is just Ms B being, well, Ms B) AFAIK, this track was not intentionally designed at a torture test, but has certainly proven to be.
This recording does not have the same effect on Fostex FE127 in very similar bipole MLTL configuration. While up to the overload point, the FR125 maintains a clear superiority in terms of low end weight and extension, it never quite catches up to the midrange of the FE127 ; and don't get me started about the FE108E Sigma - but that's another story,
We've somewhat tamed this by stuffing the ports in both the Onkens and MLTLs - I'm not sure that Dave has yet graphed the results, but I'm sure that some fiddling could optimize the aperiodic loading.
Bottoming Out the FR125S
Chris,
We do need to keep in mind that the WR125S and FR125S are 4.5 inch diameter drivers. Hence, they are not be capable of delivering subwoofer level output for low bass material. They do have significantly greater Xmax than the Fostex drivers. But the CSS drivers have lower SPL sensitivity than the Fostex units. Now given the CSS units' excursion and power handling capabilities, they run rings around the Fostex drivers for bass. Bottom line is that each brand of drivers have positive and negative issues to consider for the specific application.
The bipole ML-TL configuration helps to prevent low end bottoming by it use of two drivers versus just one. You get 3 dB more acoustic output. But, I would recommend that the user who wants chest pounding bass should expect to use a subwoofer crossed in the 50-70 Hz area. This frequency range will help relieve these small and blend with the FR125S and WR125S midrange output. Realize that the Fostex drivers would need significantly higher crossover frequencies because of their limited excursion.
Jim
Chris,
We do need to keep in mind that the WR125S and FR125S are 4.5 inch diameter drivers. Hence, they are not be capable of delivering subwoofer level output for low bass material. They do have significantly greater Xmax than the Fostex drivers. But the CSS drivers have lower SPL sensitivity than the Fostex units. Now given the CSS units' excursion and power handling capabilities, they run rings around the Fostex drivers for bass. Bottom line is that each brand of drivers have positive and negative issues to consider for the specific application.
The bipole ML-TL configuration helps to prevent low end bottoming by it use of two drivers versus just one. You get 3 dB more acoustic output. But, I would recommend that the user who wants chest pounding bass should expect to use a subwoofer crossed in the 50-70 Hz area. This frequency range will help relieve these small and blend with the FR125S and WR125S midrange output. Realize that the Fostex drivers would need significantly higher crossover frequencies because of their limited excursion.
Jim
Chrisb,
My experience with the FR125S in a TL is very close to what Jim describe. I have absolutely no bottoming out at very high levels, and the bass is strong (too strong?) and accurate all the way down.
I listened to the Patricia Barber Track you refer to (as well as the Autumn Leaves track on the nightclub album), without any stress, and at realistic levels.
I noticed that on my Pionner 15 watts vintage amp, the amp simply could not pump out enough power, so it stumbled and coughed a few times, while when using the heavy muscle of my small (60W) Bryston amp, things were very well controlled up untill clipping (which happens at around 100W).
Could what you experienced by caused by a mechanical problem with your units? or a leak in the enclosure that would unload the driver?
My experience with the FR125S in a TL is very close to what Jim describe. I have absolutely no bottoming out at very high levels, and the bass is strong (too strong?) and accurate all the way down.
I listened to the Patricia Barber Track you refer to (as well as the Autumn Leaves track on the nightclub album), without any stress, and at realistic levels.
I noticed that on my Pionner 15 watts vintage amp, the amp simply could not pump out enough power, so it stumbled and coughed a few times, while when using the heavy muscle of my small (60W) Bryston amp, things were very well controlled up untill clipping (which happens at around 100W).
Could what you experienced by caused by a mechanical problem with your units? or a leak in the enclosure that would unload the driver?
robertG said:
So far it happens on every instance of a sample set of 6 different pair speakers (WR or FR) half of which were bipoles. This is a problem that was 1st mentioned to me by Tim Forman & Al Wooley before i ever saw a WR or FR. It may well be tied in with clipping of the amplifier -- the biggest amp we have used is a 25W BGT NIGC (it is unfortunate that there seems to be an inverse relationship between power & potential amplifier quality).
From my point of view it is not unexpected & is life trying to get max bass out of a 125mm speaker. The bass on these drivers is tremendous (as you say -- even too much in the "right" box), i just think it important that people know that they may experience this problem with ported enclosures (or big sealed as well) -- it is quite dramatic when it happens. It does not subtract from my belief that this is a fantastic driver for the price.
Knowing about this, and that it is easy to get too much bottom out of the driver, means that one can consider boxes that one would normally discard because they restrict the bass output.
As i have said for the last 25 years, every good speaker deserves an active woofer (with a high pass for the drivers above) because the biggest benefit is improved midrange -- this little driver just gives way more in the LF than anyone has a right to expect, meaning lower XOs (if you add woofers), easier integration, and the option of living without happily. IMHO one of the very best set of compromises to get a FR driver with extension on both ends in a package that doesn't cost an arm & a leg, Bob & Dan get applause from me for their efforts.
I hope that this driver sees huge success, as i can only guess what the FR125 Special Edition (wholly a fantasy in my mind) might achieve.
dave
******* WARNING: ABOSLUTE HACK ATTEMPTING TO EVALUATE SPEAKER DESIGN ***************
I built GM's MLTL per the design on a previous post.
(thanks Greg)
>45 Hz ML-TL, driver at ~ear height (~+/- 2 dB):
>
>L = 39.56"
>CSA = 43.68"^2
>driver down ~3.3"
>vent = 3" dia. x 3" near/at the bottom
>stuffing density = ~0.3 lbs/ft^3 from top down ~30"
>
>All dims inside and use stuffing in the bottom portion
>of the ML-TLs to 'tighen up' the bass to get a better
>blend in-room if desired.
I stuffed top 30" of each cabinet with about 4 ounces
of polyfil (I bought a 12 ounce bag, and used about one
third of it in each cab).
With my DCX2496 I have implemented a little baffle step
at about 500 hertz (+3db shelving lowpasss), and a low
cut 48DB L-R at 25 hertz.
Speakers were already broken in - 7 liter vented per
Planet 10's site (Thanks Dave).
I have been listening to a broad range of music on
shoutcast and CD, and am very pleased with what
I hear.
I just cannot believe how much bass I am getting out of
these little guys. I am NOT saying that they are going
to replace my 2 JBL SUB1500s. However, I AM sure that
unless I am watching Jurrasic Park I will have no need
to un-mute the Subs.
I am currently listening to "Appalachia Waltz" with cellist
Yo-Yo Ma, double bassist Edgar Meyer and violinist Mark
O'Connor. The capability of these speakers to reproduce
every nuance of these three viols is just outstanding.
No bottoming out yet - Maybe I'll push them hard this
wekend and see if I can get them to misbehave.
Maybe they just dont like Canadians??????
-herm
I built GM's MLTL per the design on a previous post.
(thanks Greg)
>45 Hz ML-TL, driver at ~ear height (~+/- 2 dB):
>
>L = 39.56"
>CSA = 43.68"^2
>driver down ~3.3"
>vent = 3" dia. x 3" near/at the bottom
>stuffing density = ~0.3 lbs/ft^3 from top down ~30"
>
>All dims inside and use stuffing in the bottom portion
>of the ML-TLs to 'tighen up' the bass to get a better
>blend in-room if desired.
I stuffed top 30" of each cabinet with about 4 ounces
of polyfil (I bought a 12 ounce bag, and used about one
third of it in each cab).
With my DCX2496 I have implemented a little baffle step
at about 500 hertz (+3db shelving lowpasss), and a low
cut 48DB L-R at 25 hertz.
Speakers were already broken in - 7 liter vented per
Planet 10's site (Thanks Dave).
I have been listening to a broad range of music on
shoutcast and CD, and am very pleased with what
I hear.
I just cannot believe how much bass I am getting out of
these little guys. I am NOT saying that they are going
to replace my 2 JBL SUB1500s. However, I AM sure that
unless I am watching Jurrasic Park I will have no need
to un-mute the Subs.
I am currently listening to "Appalachia Waltz" with cellist
Yo-Yo Ma, double bassist Edgar Meyer and violinist Mark
O'Connor. The capability of these speakers to reproduce
every nuance of these three viols is just outstanding.
No bottoming out yet - Maybe I'll push them hard this
wekend and see if I can get them to misbehave.
Maybe they just dont like Canadians??????
-herm
I'm getting some bottoming out with the FR125S in the recomended 7L rear ported box, but only at high spl. Its actually too loud for normal listning. On some heavy bass tracks they play fine, on others like Erica Badu they will bottom out but only with like 100W fed to them.
I originaly stuffed the cabs full of dampening, this provided very nice mids and laid back bass. Now I have minimal dampening and the bass is more forward. Dampening seems to have little effect on bottoming out....
I originaly stuffed the cabs full of dampening, this provided very nice mids and laid back bass. Now I have minimal dampening and the bass is more forward. Dampening seems to have little effect on bottoming out....
SCREEM said:
I had a problem with bottoming on Modern Cool and on a Beck CD, in a 7L cabinet with stuffed port (stuffed with a pair of MacGregor Happy Foot socks). I measured 90 dB with a Radio Shack digital meter (at my listening chair) on the FAST setting. I was using a good quality 50W SS amp.
I agree with your comment about too loud for normal listening, but I would qualify it to say "with these speakers". A single FR125S in a 7L cabinet starts sounding a bit stressed above 80 dB IME and is uncomfortable above 90 dB. Wonderful when operated below its limits though.
Volume is not a problem in my secondary system, but it would be a problem if it was my only system.
I have not tried a larger cab... I am using some vintage Quad 50E mono blocks wich are conservatively rated 50 watts each. I have to crank them way up to get some poping. If I back off the power just a tad to eliminate the poping, they sound a a little strained, but I would estimated I'm getting 100db at this point, in a nearfield listening situation.
The FR125S is not efficient in the 7 litre cab, But they have an exellent sound for listening at comfertable levels 70-80db.
I love them!
The FR125S is not efficient in the 7 litre cab, But they have an exellent sound for listening at comfertable levels 70-80db.
I love them!
First listening impressions were good and no bottoming out. They seem capable of filling the garage with plenty of sound and no straining. Here's some pics
http://www.diyaudio.com/forums/showthread.php?postid=879046#post879046
Around 22 or 24 litres
http://www.diyaudio.com/forums/showthread.php?postid=879046#post879046
Around 22 or 24 litres
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