Having "cut my teeth" designing a fairly simple 2-way with the WR125 and the DX19 tweeter, I am now evaluating options for the FR125. So, I am opening up the discussion to the experts here to help me decide what makes sense.
I want to improve upon my older WR125S design in at least two key areas: efficiency/power handling and upper frequency performance (as good as it is for the money, the DX19 still has a nasty resonance at 4K which can be heard even with the 2nd order x-over).
The designs I am considering are:
1. 1.5 configuration using one FR125 running full range and a second FR on the same baffle running only in the lower bandwidth to provide baffle step correction. I expect that this would improve efficiency by about 6db (if wired in parallel) and avoid the need to apply baffle step correction the x-over. My modeling suggests that these two drivers in a tuned ported enclosure should play flat down to 50 hz. My concern is whether or not the mid-bass/mid-range will get muddied with the second driver playing on the same baffle?
2a. TMM configuration using a smoother/better tweeter than the DX19 - probably a 1" textile dome tweeter - with the same 1.5 configuration listed in #1 this then becomes a more conventional 2.5 configuration. Concern here is whether adding a tweeter would help or hurt the overall system performance (assuming a properly designed x-over)?
2b. One other twist on this idea in 2a is to use the FR125s as a dedicated mid/tweeter (if it's HF performance is that good) and then to use one or two larger woofers - perhaps 2x8" or 2x10" drivers in a TWW configuration where the woofers provide really solid bass and mid-bass performance. The concerns here are whether or not the FR125 can really replace a tweeter and how much sound coherence would be lost by integrating the woofers with the FR125 in the mid-bass below 1k. I suspect that this would defeat the purpose of using the FR125 in the first place since coherency is one of the key benefits of going full range.
3. MTM configuration using two FRs and a 1" tweeter. Concern is that for the MTM to work properly the x-over has to be low - let's say around 2k - I suspect that this defeats the purpose of using the FR125s and some other driver might be better suited to the application - perhaps a larger 6.5" or 7" driver. My guess is that this setup just doesn't make good sense.
I do realize that, when compared to the WR125s, the FR125S has better upper frequency extension, has a smoothed mid-band around 1k and plays the top octave better off axis than the WR as shown here:
Link
On the other hand not having one to listen to yet but knowing that I prefer both detail and excellent off-axis response in the upper two octaves, I am not sure if I will be happy with the high frequency performance of the FR compared with a good dome tweeter? This question is critical as its answer will play a pivotal role in determing the configuration for my next design.
There is also the new question of sealed vs. ported. In my opinion the Qts of the WR was too high to reasonably consider a sealed design and my listening tests of the WR in a sealed .25 ft^3 also confirmed that suspicion. However, the FR with its lower Qts represents an opportunity to explore the sealed design. As much as I like low end, I would bet that removing the group delay introduced by the ported configuration and using a sealed tuning with an F3 of around 90 hz might be quite nice when paired with a dedicated sub in a sub-sat configuration.
So there is my current thinking - any feedback or input on these ideas would be appreciated.
A couple of design constraints include no open baffle solutions and no dipole solutions - we can save those debates for another day.
Thanks in advance.
Andrew
I want to improve upon my older WR125S design in at least two key areas: efficiency/power handling and upper frequency performance (as good as it is for the money, the DX19 still has a nasty resonance at 4K which can be heard even with the 2nd order x-over).
The designs I am considering are:
1. 1.5 configuration using one FR125 running full range and a second FR on the same baffle running only in the lower bandwidth to provide baffle step correction. I expect that this would improve efficiency by about 6db (if wired in parallel) and avoid the need to apply baffle step correction the x-over. My modeling suggests that these two drivers in a tuned ported enclosure should play flat down to 50 hz. My concern is whether or not the mid-bass/mid-range will get muddied with the second driver playing on the same baffle?
2a. TMM configuration using a smoother/better tweeter than the DX19 - probably a 1" textile dome tweeter - with the same 1.5 configuration listed in #1 this then becomes a more conventional 2.5 configuration. Concern here is whether adding a tweeter would help or hurt the overall system performance (assuming a properly designed x-over)?
2b. One other twist on this idea in 2a is to use the FR125s as a dedicated mid/tweeter (if it's HF performance is that good) and then to use one or two larger woofers - perhaps 2x8" or 2x10" drivers in a TWW configuration where the woofers provide really solid bass and mid-bass performance. The concerns here are whether or not the FR125 can really replace a tweeter and how much sound coherence would be lost by integrating the woofers with the FR125 in the mid-bass below 1k. I suspect that this would defeat the purpose of using the FR125 in the first place since coherency is one of the key benefits of going full range.
3. MTM configuration using two FRs and a 1" tweeter. Concern is that for the MTM to work properly the x-over has to be low - let's say around 2k - I suspect that this defeats the purpose of using the FR125s and some other driver might be better suited to the application - perhaps a larger 6.5" or 7" driver. My guess is that this setup just doesn't make good sense.
I do realize that, when compared to the WR125s, the FR125S has better upper frequency extension, has a smoothed mid-band around 1k and plays the top octave better off axis than the WR as shown here:
Link
On the other hand not having one to listen to yet but knowing that I prefer both detail and excellent off-axis response in the upper two octaves, I am not sure if I will be happy with the high frequency performance of the FR compared with a good dome tweeter? This question is critical as its answer will play a pivotal role in determing the configuration for my next design.
There is also the new question of sealed vs. ported. In my opinion the Qts of the WR was too high to reasonably consider a sealed design and my listening tests of the WR in a sealed .25 ft^3 also confirmed that suspicion. However, the FR with its lower Qts represents an opportunity to explore the sealed design. As much as I like low end, I would bet that removing the group delay introduced by the ported configuration and using a sealed tuning with an F3 of around 90 hz might be quite nice when paired with a dedicated sub in a sub-sat configuration.
So there is my current thinking - any feedback or input on these ideas would be appreciated.
A couple of design constraints include no open baffle solutions and no dipole solutions - we can save those debates for another day.
Thanks in advance.
Andrew
sounding like a broken record, but
can you say bipole?
try this:
http://www.planet10-hifi.com/sealed.html
This was initially an experiment to see how a WR & cheap tweeter could compare to the FR. Frankly, I prefer the former as the direct radiating set. Using a pair of WR per side could save enough to afford any one of a half a dozen or so cheap tweets, since they can be simply rolled in where the WR starts to fall. Of course you could always get spendy - Aurum Cantus ribbons etc.
Since I'm not a huge fan of big bass, I'm not missing not the extra cost of crossover and additional drivers. However, if you think you need your bass super-sized, the Adire Extremis utilizing the same motor technology would be a logical, if not inexpensive choice. Amazing bass from such a small cone area, but with the same efficiency trade-off as the CSS XBL drivers.
can you say bipole?
try this:
http://www.planet10-hifi.com/sealed.html
This was initially an experiment to see how a WR & cheap tweeter could compare to the FR. Frankly, I prefer the former as the direct radiating set. Using a pair of WR per side could save enough to afford any one of a half a dozen or so cheap tweets, since they can be simply rolled in where the WR starts to fall. Of course you could always get spendy - Aurum Cantus ribbons etc.
Since I'm not a huge fan of big bass, I'm not missing not the extra cost of crossover and additional drivers. However, if you think you need your bass super-sized, the Adire Extremis utilizing the same motor technology would be a logical, if not inexpensive choice. Amazing bass from such a small cone area, but with the same efficiency trade-off as the CSS XBL drivers.
Chris:
Thanks for the feedback. I was trying hard to avoid sending this thread into the debate over bipoles vs. monopoles but I have never really cared for the sound of any I've ever heard. Perhaps the FR would be an exception?
On the other hand, I am really thinking seriously about a 1.5 or 2.5 configuration and was hoping to get some thoughts on those ideas specifically . . .
The closest design I could find on-line to what I am describing is here (note this is more like a mini line array than a 2.5 and is using the WR not the FR):
link
Some feedback on the quality of the top two octaves of output from the FR and thoughts on the impact of "blending" a second FR for low frequency baffle step correction would be greatly appreciated.
Regards,
Andrew
Thanks for the feedback. I was trying hard to avoid sending this thread into the debate over bipoles vs. monopoles but I have never really cared for the sound of any I've ever heard. Perhaps the FR would be an exception?
On the other hand, I am really thinking seriously about a 1.5 or 2.5 configuration and was hoping to get some thoughts on those ideas specifically . . .
The closest design I could find on-line to what I am describing is here (note this is more like a mini line array than a 2.5 and is using the WR not the FR):
link
Some feedback on the quality of the top two octaves of output from the FR and thoughts on the impact of "blending" a second FR for low frequency baffle step correction would be greatly appreciated.
Regards,
Andrew
ABS said:
One thing I want to try in the new year is a pair of sealed FR's and an Extremis in a 2.1 config.
The FR's have a natural sounding mid/high and really great bass for smaller rooms, but for a larger system, say HT or large rooms, they need to be augmented in the bottom for SPL without bottoming out.
Yes, if the efficiency of the FR is anything like the WR (and I believe they are VERY similar), then the FR won't be able to take too much power or play all that loud when it is being asked to play low frequency material.
I do like your sub/sat idea but even a single FR in a sealed box would still require baffle step correction, no?
But try modeling 2 FR's in a bass reflex 1.0 cu ft. cabinet tuned to 50 hz and tell me if you still think a subwoofer would be mandatory?
Andrew
I do like your sub/sat idea but even a single FR in a sealed box would still require baffle step correction, no?
But try modeling 2 FR's in a bass reflex 1.0 cu ft. cabinet tuned to 50 hz and tell me if you still think a subwoofer would be mandatory?
Andrew
ABS said:
Andrew:
I guess my bias towards the bipole could cloud my judgement, but during the past 3 years, I haven't built one (with the design assistance of Dave Dlugos
) that I and others didn't like. Many of those preceded the CSS drivers, and used mostly Fostex 103( & variants) as well as FE127, and even some "no-names" Be that as it may - to answer your question regarding the top-end performance of the FR125. In the few pair that I've heard in direct comparison ( at Bob & Al's "houseparties" ), it simply does not have quite the shimmering air and absolute speed of a ribbon such as the Aurum Cantus etc., but compared to a more mainstream fabric or plastic dome, it's a much closer horserace. (and don't even talk to me about metal domes)
But the premium paid with the ribbon is the very complex network required to protect the tweeter if crossed over any lower than 4-6K.
I can't remember if you mentioned whether enclosure size was an issue, or if you're considering 1.5 or 2.5ways with the FR/WR due to existing driver stock.
Crossovers can start to get very complicated once you start dealing with the additional issues of BSC, impedance compensation, and comb-filtering/lobing artifacts that MTM /TMM on small baffles can create, and have destroyed the midrange transparency and coherency of many a good combination of drivers of any make.
Depending on application, and acceptable enclosure size, my guess is that a simple 2-way with a single FR125 and Extremis would be more than sufficient SPL and bass output, while eliminating the need for any crossover in the critical midrange & up band. If you think the CSS drivers have amazing bass for their size, you need to hear the Adire Extremis. ( just one per channel though
)There's a decent compilation of DIY tested enclosures for many combinations of the CSS driver at:
http://www.planet10-hifi.com/boxes.html
I've built several of them myself, but you already know what my preferences are.
Re: Re: sounding like a broken record, but
"big" as in fat, sloppy, inarticulate - you know Home Theatre
anything below 100K is too low for my taste (but then my hearing's not totally shot yet)
thanks, maybe BBQ & beer season - gotta be stag nite tho - my wife has heard above Dave's place - I don't dare try to describe casa Weldon
Cal Weldon said:
No?
"big" as in fat, sloppy, inarticulate - you know Home Theatre
Well quit crossing them over so low. No wonder you think they sound like
anything below 100K is too low for my taste (but then my hearing's not totally shot yet)
Oh and Chris,and Merry Christmas to you and yours. Hope to come over sometime in the spring.
thanks, maybe BBQ & beer season - gotta be stag nite tho - my wife has heard above Dave's place - I don't dare try to describe casa Weldon
Chris - In regard to your idea of using 1 FR125 and a single large woofer (Extremis was the one you mentioned), am I correct to assume that you would then be correcting for the FR125 baffle step with the woofer as part of a modified 1.5 configuration? Or would you propose correcting for the baffle step with the x-over (thereby losing efficiency) and run the large woofer effectively as a subwoofer? If you are suggesting using the large woofer to correct for the baffle step, wouldn't I be better off just using another FR125 since the wouldn't be any difference in tonality and/or frequency response thereby resulting in (hopefully) a smoother transition between the two drivers?
Please realize that, although I don't have nearly the same experience as you, I am using simulation software and I do understand the basics of speaker and x-over design.
I don't have any stock of the WR drivers although I conceivably use one WR with one FR in a 1.5 setup. This could result in a smaller enclosure. I do like the tuning options for the FR much better than the WR even though the ported configuration does require that larger enclosure to get the most out of them.
I wouldn't consider using a ribbon due to the poor vertical response they usually exhibit - more likely I would go with a high quality low distortion 1" fabric tweeter - these can usually be crossed much lower than the ribbons - but by using the FR I don't think I'd need to cross so low anyway!
The biggest issue I am facing with any of the multi-woofer designs is the queston of $ value. By the time I add a decent tweeter and two FR's I am up to at least $175 in drivers. At that price point there are many other options I could consider which might provide equal or better performance in a straight 2-way configuration . . . If we accept that statement then it becomes a question of whether or not an FR based 1.5 or 2.5 system would be at least as good as a competing 2-way at that same price point.
Please realize that, although I don't have nearly the same experience as you, I am using simulation software and I do understand the basics of speaker and x-over design.
I don't have any stock of the WR drivers although I conceivably use one WR with one FR in a 1.5 setup. This could result in a smaller enclosure. I do like the tuning options for the FR much better than the WR even though the ported configuration does require that larger enclosure to get the most out of them.
I wouldn't consider using a ribbon due to the poor vertical response they usually exhibit - more likely I would go with a high quality low distortion 1" fabric tweeter - these can usually be crossed much lower than the ribbons - but by using the FR I don't think I'd need to cross so low anyway
!The biggest issue I am facing with any of the multi-woofer designs is the queston of $ value. By the time I add a decent tweeter and two FR's I am up to at least $175 in drivers. At that price point there are many other options I could consider which might provide equal or better performance in a straight 2-way configuration . . . If we accept that statement then it becomes a question of whether or not an FR based 1.5 or 2.5 system would be at least as good as a competing 2-way at that same price point.
Warning; having taken a final preview of this post, I realize it's run rather long - I tend to do that sometimes, sorry.
Oh yeah, like all posts on these types of forums, the free advice contained herein is based on my personal experience and preferences, and is worth exactly what you paid for it.
Andrew; to paraphrase Dave Dlugos, quite possibly the greatest thing about drivers like the FR125 ( actually, there are arguably very few with all the performance characteristics of the FR125 at that size and price) is their ability to allow an adventurous DIYer to open the door and step outside of the "Madisound/ Danish hi-fi" school of over-engineered* loudspeaker design
*italics mine - referring to the sometimes painstaking measurement and computer modelling efforts taken to achieve objectively "flat" frequency response, and excessive cabinet bracing / damping employed in attempts to eliminate enclosure resonances.
In many cases the complexity of passive circuitry to achieve the former, and cabinet dimensions and weights required for the latter, can take away far more from the emotional impact of the music than any "problems" they solve. Been, there - done that.
So, like many other FullRangers, I'm currently at the place where I'll more than happily accept an audio system with a certain amount of "personality", rather than none at all. Compromise is fine, and each to their own taste.
For example, just yesterday evening I spent several very enjoyable hours listening to a newly completed pair of Bottlehead Paramount 300B amps, in a system (not mine
) that normally runs a considerably lower powered amp ( Welborne DRD 45s) , with Cain/Cain Abby loudspeakers. Of course, the initially reaction on plugging in the higher powered amps ( 8W vs >2w) is "holy snappin arshows, these speakers do so have bass, and certainly more dynamics. Then after 3 or so hours, you plug the 45's back in and there are subtleties of texture, detail and emotional connection that I defy anyone to objectively measure or at the same time ignore.
Yes the large scale obvious differences remain - the 300B amp has more "balls", no question about it; but the "lesser" amp does many things that I prefer. What is the best compromise between the 2 amps? Perhaps a 2A3? OK then, which circuit, etc etc.
Back to the question of the FR125 speakers. As mentioned previously, I've built a few different speaker designs with combinations of the FR & WR, with and without tweeters. I'll also repeat myself regarding bipole - to oversimplify - I've found it to be almost a free lunch (except of course for the cost of the extra drivers). Compared to issues encountered in MM / MTM / TMM configurations, you can kiss the BSC and/or .5 way crossover issues goodbye. If you're concerned that your application will exceed the performance limits of the FR or WR125, then it would seem logical to me to mate with a woofer with similiar technology, materials and sensitivity. The Extremis takes the performance capabilities of the XBL motor technology to a new level - in a word they ****** rock.
In the case under discussion, my approach would probably be to use a single FR 125 and Extremis per side, and biamp, using PLLXO for the hipass . They can easily be built into separate plug-in module hobby cases, or even at the amp's input jacks.
Since the amp driving the FR125 is already hi-pass filtered, it's safe to operate it without any passive crossover. It is designed as a full range driver after all, and while it is possible to exceed the mechanical excursion and voice coil power handling limits of any driver ever made, it'll get reaaaallly loud first.
Depending on the frequency at which you want to cross over to the woofer, you can get away with a very small enclosure volume for the FR (for example the recommended 7 litres ported, or Dave Dlugos' excellent sounding 13 litre mini-onken design are designed for full range), leaving plenty of room in the same floor standing enclosure for the woofer. The recommended volumes for the Extremis are pretty tiny as well; 9.5 litres sealed/100% fill, or 21 liters, tuned to 33Hz ( is that low enough for you?) While I'm not really a big fan, any of the inexpensive sub plate amps would make for an easy experiment in bi-amping; some have reasonably flexible (if not sonically transparent) crossovers, and it wouldn't be too difficult to adjust the enclosure dimensions to accomodate the amp.
Extremis data sheet:
http://www.creativesound.ca/pdf/Extremis6.8Datasheet.pdf
I haven't played around with this driver yet, although I've heard systems of Al Wooley's and Tim Foreman's. It's scary good, but just not really my cup of tea.
And in closing, while probably only an issue for the flea-power/SET amp systems, the outstanding performance of the Adire XBL motor technology comes with an additional price to the cost of the drivers - their moderate sensitivity compared to traditional FR drivers. I can easily clip my RH84 SEP monoblocks and even (at much louder levels ) an EL84 PP triode amp, on either the MLTL or sealed (both bipoles) .
Oh yeah, like all posts on these types of forums, the free advice contained herein is based on my personal experience and preferences, and is worth exactly what you paid for it.
Andrew; to paraphrase Dave Dlugos, quite possibly the greatest thing about drivers like the FR125 ( actually, there are arguably very few with all the performance characteristics of the FR125 at that size and price) is their ability to allow an adventurous DIYer to open the door and step outside of the "Madisound/ Danish hi-fi" school of over-engineered* loudspeaker design
*italics mine - referring to the sometimes painstaking measurement and computer modelling efforts taken to achieve objectively "flat" frequency response, and excessive cabinet bracing / damping employed in attempts to eliminate enclosure resonances.
In many cases the complexity of passive circuitry to achieve the former, and cabinet dimensions and weights required for the latter, can take away far more from the emotional impact of the music than any "problems" they solve. Been, there - done that.
So, like many other FullRangers, I'm currently at the place where I'll more than happily accept an audio system with a certain amount of "personality", rather than none at all. Compromise is fine, and each to their own taste.
For example, just yesterday evening I spent several very enjoyable hours listening to a newly completed pair of Bottlehead Paramount 300B amps, in a system (not mine
) that normally runs a considerably lower powered amp ( Welborne DRD 45s) , with Cain/Cain Abby loudspeakers. Of course, the initially reaction on plugging in the higher powered amps ( 8W vs >2w) is "holy snappin arshows, these speakers do so have bass, and certainly more dynamics. Then after 3 or so hours, you plug the 45's back in and there are subtleties of texture, detail and emotional connection that I defy anyone to objectively measure or at the same time ignore.Yes the large scale obvious differences remain - the 300B amp has more "balls", no question about it; but the "lesser" amp does many things that I prefer. What is the best compromise between the 2 amps? Perhaps a 2A3? OK then, which circuit, etc etc.
Back to the question of the FR125 speakers. As mentioned previously, I've built a few different speaker designs with combinations of the FR & WR, with and without tweeters. I'll also repeat myself regarding bipole - to oversimplify - I've found it to be almost a free lunch (except of course for the cost of the extra drivers). Compared to issues encountered in MM / MTM / TMM configurations, you can kiss the BSC and/or .5 way crossover issues goodbye. If you're concerned that your application will exceed the performance limits of the FR or WR125, then it would seem logical to me to mate with a woofer with similiar technology, materials and sensitivity. The Extremis takes the performance capabilities of the XBL motor technology to a new level - in a word they ****** rock.
In the case under discussion, my approach would probably be to use a single FR 125 and Extremis per side, and biamp, using PLLXO for the hipass . They can easily be built into separate plug-in module hobby cases, or even at the amp's input jacks.
Since the amp driving the FR125 is already hi-pass filtered, it's safe to operate it without any passive crossover. It is designed as a full range driver after all, and while it is possible to exceed the mechanical excursion and voice coil power handling limits of any driver ever made, it'll get reaaaallly loud first.
Depending on the frequency at which you want to cross over to the woofer, you can get away with a very small enclosure volume for the FR (for example the recommended 7 litres ported, or Dave Dlugos' excellent sounding 13 litre mini-onken design are designed for full range), leaving plenty of room in the same floor standing enclosure for the woofer. The recommended volumes for the Extremis are pretty tiny as well; 9.5 litres sealed/100% fill, or 21 liters, tuned to 33Hz ( is that low enough for you?) While I'm not really a big fan, any of the inexpensive sub plate amps would make for an easy experiment in bi-amping; some have reasonably flexible (if not sonically transparent) crossovers, and it wouldn't be too difficult to adjust the enclosure dimensions to accomodate the amp.
Extremis data sheet:
http://www.creativesound.ca/pdf/Extremis6.8Datasheet.pdf
I haven't played around with this driver yet, although I've heard systems of Al Wooley's and Tim Foreman's. It's scary good, but just not really my cup of tea.
And in closing, while probably only an issue for the flea-power/SET amp systems, the outstanding performance of the Adire XBL motor technology comes with an additional price to the cost of the drivers - their moderate sensitivity compared to traditional FR drivers. I can easily clip my RH84 SEP monoblocks and even (at much louder levels ) an EL84 PP triode amp, on either the MLTL or sealed (both bipoles) .
Chris:
I appreciate your detailed response and your perspective on these questions. My response will be somewhat lengthy as well.
I do realize that the design of virtually every piece of audio equipment is one of compromise - (whether it be speaker design, amplifier design, d/a design, turntable/cartridge design, etc.). The example you gave of the comparison between the two amps is a good one since it exemplifies the point well. I also agree with you that what sounds "good" should be the priority and not so much attention applied to acheiving an absolutely flat frequency response. Truth be told, I usually like my speakers to have a slightly forward midrange but an overall balanced sound and I typically don't care for speakers which are too "laid back". But, this is just my taste in how to tune the speaker. Does this imply an absolutely flat on-axis response curve is required, no it doesn't. On the other hand, I do still feel that the goal of having a "relatively" flat speaker response on axis plus a good power distribution off-axis is fairly important to making a speaker sound good. Mind you my design philosophy doesn't require perfection in any area - just good overall sound.
So now we can have that philosophical discussion around what speaker designs are best and what compromises we can live with. In the WR minimonitor I designed, I had learned that the power handling was an issue for me - using the speakers for home theater (without a sub) or even for music at a moderate to high volume level could easily result in the speaker bottoming out and I am sure causing a farily large quantity of low frequency distortion just prior to reaching the point of bottoming out. I also noted that the upper frequency range was no where near good enough for my taste either on-axis or off axis). I also noted that the mid-range was just too hot and the mid-bass was too recessed as a result of the baffle step I would expect the FR to behave similarly. I am making some assumptions regarding how I expect the FR to perform based on my experience with the WR. I expect that the power handling issue will continue as will the poor upper frequency off-axis performance and the need for BSC.
So now we can really get into the questions of where to compromise the design? Please bear with me here as I don't know much about bipoles but I do find the bipole design to be intriguing. I see how it corrects for baffle step issue as well as improving power handling, but how does that solution address the relatively poor off-axis upper frequency response of the FR? Also, doesn't the bipole design reduce the "point source" benefits of a full range driver by reflecting sound front and rear? And then what about all the phase shifting that occurs at the sound wave interface between the two drivers that must also create some undesirable artifacts, no?
In regard to your second recommendation, bi-amping the FR with an Extremis in each enclosure, this seems like a fairly good idea, but at that point, why wouldn't I just put a single FR in a small sealed cabinet and build a single dedicated sub? Oh, the problems with are that I would still have to deal with the baffle step issue ergo reduced driver efficiency and I still wouldn't be addressing the upper frequency off-axis issues. On the other hand the power handling problem would be largely corrected since the F3 would be around 90hz or so in the sealed box and the sub would handle all the really low stuff . . . Perhaps a sealed FR with a tweeter and BSC plus a sub makes sense?
At the end of the day I am agreeing with you that simpler is better but only when it makes sense within the design criteria/goals. Maybe the issue is my preconceived notions of how to build a full range speaker. Even considering all the things the FR does well it is in itself a series of design compromises. These are the compromises I am trying to address in whatever design I build. I always come back to the idea of my wanting to "solve" for the noted off-axis problems and power handling problems without losing the coherency provided by having a "point source" driver. In a way, you and I are agreeing on the power handling and baffle step questions both of your recommendations address this issue (add a woofer down low or use a bipole configuration). On the other hand, why ignore the upper frequency issues? If the x-over is high enough it should not destroy the overall voicing from FR and should provide significant additional detail and clarity plus much better off-axis response which I think would help the imaging of the overall speaker.
Then when I start to think about how to build a simple x-over, the concept of using low order slopes with drivers that have wide bandwidths always seems appealing to me - it is simple and keeps the parts count low which are good things in my book. The point is it is difficult to find a really good mid-woofer that can come anywhere near the performance of the FR at its price point. So why not shift the perpsective slightly and take advantage of those things the FR does so well, but reduce the impact of all those things it doesn't excel at?
Andrew
I appreciate your detailed response and your perspective on these questions. My response will be somewhat lengthy as well.
I do realize that the design of virtually every piece of audio equipment is one of compromise - (whether it be speaker design, amplifier design, d/a design, turntable/cartridge design, etc.). The example you gave of the comparison between the two amps is a good one since it exemplifies the point well. I also agree with you that what sounds "good" should be the priority and not so much attention applied to acheiving an absolutely flat frequency response. Truth be told, I usually like my speakers to have a slightly forward midrange but an overall balanced sound and I typically don't care for speakers which are too "laid back". But, this is just my taste in how to tune the speaker. Does this imply an absolutely flat on-axis response curve is required, no it doesn't. On the other hand, I do still feel that the goal of having a "relatively" flat speaker response on axis plus a good power distribution off-axis is fairly important to making a speaker sound good. Mind you my design philosophy doesn't require perfection in any area - just good overall sound
. So now we can have that philosophical discussion around what speaker designs are best and what compromises we can live with. In the WR minimonitor I designed, I had learned that the power handling was an issue for me - using the speakers for home theater (without a sub) or even for music at a moderate to high volume level could easily result in the speaker bottoming out and I am sure causing a farily large quantity of low frequency distortion just prior to reaching the point of bottoming out. I also noted that the upper frequency range was no where near good enough for my taste either on-axis or off axis). I also noted that the mid-range was just too hot and the mid-bass was too recessed as a result of the baffle step I would expect the FR to behave similarly. I am making some assumptions regarding how I expect the FR to perform based on my experience with the WR. I expect that the power handling issue will continue as will the poor upper frequency off-axis performance and the need for BSC.
So now we can really get into the questions of where to compromise the design? Please bear with me here as I don't know much about bipoles but I do find the bipole design to be intriguing. I see how it corrects for baffle step issue as well as improving power handling, but how does that solution address the relatively poor off-axis upper frequency response of the FR? Also, doesn't the bipole design reduce the "point source" benefits of a full range driver by reflecting sound front and rear? And then what about all the phase shifting that occurs at the sound wave interface between the two drivers that must also create some undesirable artifacts, no?
In regard to your second recommendation, bi-amping the FR with an Extremis in each enclosure, this seems like a fairly good idea, but at that point, why wouldn't I just put a single FR in a small sealed cabinet and build a single dedicated sub? Oh, the problems with are that I would still have to deal with the baffle step issue ergo reduced driver efficiency and I still wouldn't be addressing the upper frequency off-axis issues. On the other hand the power handling problem would be largely corrected since the F3 would be around 90hz or so in the sealed box and the sub would handle all the really low stuff . . . Perhaps a sealed FR with a tweeter and BSC plus a sub makes sense?
At the end of the day I am agreeing with you that simpler is better but only when it makes sense within the design criteria/goals. Maybe the issue is my preconceived notions of how to build a full range speaker. Even considering all the things the FR does well it is in itself a series of design compromises. These are the compromises I am trying to address in whatever design I build. I always come back to the idea of my wanting to "solve" for the noted off-axis problems and power handling problems without losing the coherency provided by having a "point source" driver. In a way, you and I are agreeing on the power handling and baffle step questions both of your recommendations address this issue (add a woofer down low or use a bipole configuration). On the other hand, why ignore the upper frequency issues? If the x-over is high enough it should not destroy the overall voicing from FR and should provide significant additional detail and clarity plus much better off-axis response which I think would help the imaging of the overall speaker.
Then when I start to think about how to build a simple x-over, the concept of using low order slopes with drivers that have wide bandwidths always seems appealing to me - it is simple and keeps the parts count low which are good things in my book. The point is it is difficult to find a really good mid-woofer that can come anywhere near the performance of the FR at its price point. So why not shift the perpsective slightly and take advantage of those things the FR does so well, but reduce the impact of all those things it doesn't excel at?
Andrew
Andrew -
If I can read between the lines, it sounds as if you just really have an urge to do more than throw the FR in a box and listen. Even to the point of disregarding the suggestion to use the FR and Extremis, and then be done with it.
I think what Chris is saying is that, in his experience, the upper octaves of the FR are at least "good enough" if not perfect. My reading of the forum suggests that his experience is, at least relatively speaking, quite sizeable with regard to the FR and WR.
If you are at least convinced that you want to use the FR in some configuration, you could start with taking a pair and putting them in some at least semi-appropriate sealed boxes, and give a listen to the top end, just from the FR. If that's okay, then figure out what you want to do WRT woofers, BSC, and the rest. You can do the simulation, etc, _after_ you give a listen and determine whether you, personally, can live with the speaker in an at least mostly full-range mode.
Have fun with this - Pat
If I can read between the lines, it sounds as if you just really have an urge to do more than throw the FR in a box and listen. Even to the point of disregarding the suggestion to use the FR and Extremis, and then be done with it.
I think what Chris is saying is that, in his experience, the upper octaves of the FR are at least "good enough" if not perfect. My reading of the forum suggests that his experience is, at least relatively speaking, quite sizeable with regard to the FR and WR.
If you are at least convinced that you want to use the FR in some configuration, you could start with taking a pair and putting them in some at least semi-appropriate sealed boxes, and give a listen to the top end, just from the FR. If that's okay, then figure out what you want to do WRT woofers, BSC, and the rest. You can do the simulation, etc, _after_ you give a listen and determine whether you, personally, can live with the speaker in an at least mostly full-range mode.
Have fun with this - Pat
limits
Yep, "a man's gotta know his limits"
Andrew - your point is well made regarding design goals / criteria. As I think I stated in the previous post, it is possible to exceed the performance limits of any audio component, sometimes with financially catastrophic and in the case of loudspeakers, permanent aurally damaging results.
I have succeeded in grossly clipping my low power tubed amplifiers attempting to drive the FR125/bipoles to concert levels - the sound ain't pretty whether it's the amp running out of power or the speaker farting.
If I understand your last post correctly, your experience to date has been with the WR. From my personal experience, there's no question that the FR has better in room high frequency performance than the WR. Since I do my critical listening from a dedicated listening position, and likely at lower levels than you might ( i.e. in my case average of 80dB or less) it's altogether that my results are tailored for on-axis performance, and well below the driver's power compression or the room's overloading characteristics. I can live with that.
But clearly in a different situation the limits of the FR/WR can easily be identified. I don't pretend to have the single right answer for your specific case ( cause first of all, there isn't one ), and it's likely to take a process of trial and error for you to find the best performance/price solution.
The Extremis is a decent enough midwoofer that there are several designs by RAW Acoustics, using it in TM/TMM/ MTM configurations; several in fact with WR & dome or ribbon tweeters. I've heard most of these models, and any one of them is more speaker than I need, particularly in the bottom - I honestly doubt the need for a sub, but Cal would probably argue that one.
So, try the FR's in as simple a sealed box as you want - if you roll them off high enough, you can get away with very small sub-enclosure, and still have more than enough room in the same cabinet footprint for whatever midwoofer you choose. For many reasons, I've never been a fan of either BSC EQ, or single bass drivers- even if the latter is only operating for the single lowest octave, which will definitely not be the case in a home theatre situation. Of course with an adequate midbass driver and baffle dimensions, the "step" will be hard to hear.
I don't have the technical expertise to answer your questions regarding flat frequency response, off axis power distribution, etc. ; there should be other contributors who can. But I can tell you that every time I visit the local audio shop where I did most of my shopping over the past 25years, and listen to their hi-end demo systems, with speakers designed by some pretty smart engineers ( B&W, Linn, Magneplanar, Paradigm, Tannoy, Wharfedale) to meet those criteria , I don't get the same goosebumps as from the prosaic 2-way AudioNotes (warts, sticker shock and all)
As to your remarks regarding issues of bipole vs "point source" radiation patterns, you might want to read the documentation attached to the following DIY project - if you're interested in math and measurements, there's a fair bit therein :
http://www.t-linespeakers.org/projects/tlB/index.html
FWIW, I can remember when first wetting my feet in this hobby in the mid 70's, a lot of discussion in commercial and the early "underground hi-end audio press" ( that evolved into Stereophile / Absolute Sound ) on whether the ideal speaker would replicate the real world by emulating an "omni-directional point source, throughout the entire audible range" - the floating pulsating sphere; or the opposite case of a flat monopole "open window". I've heard and owned many wonderful and not-so commercial and amateur designs from both schools of thought.
Yep, "a man's gotta know his limits"
Andrew - your point is well made regarding design goals / criteria. As I think I stated in the previous post, it is possible to exceed the performance limits of any audio component, sometimes with financially catastrophic and in the case of loudspeakers, permanent aurally damaging results.
I have succeeded in grossly clipping my low power tubed amplifiers attempting to drive the FR125/bipoles to concert levels - the sound ain't pretty whether it's the amp running out of power or the speaker farting.
If I understand your last post correctly, your experience to date has been with the WR. From my personal experience, there's no question that the FR has better in room high frequency performance than the WR. Since I do my critical listening from a dedicated listening position, and likely at lower levels than you might ( i.e. in my case average of 80dB or less) it's altogether that my results are tailored for on-axis performance, and well below the driver's power compression or the room's overloading characteristics. I can live with that.
But clearly in a different situation the limits of the FR/WR can easily be identified. I don't pretend to have the single right answer for your specific case ( cause first of all, there isn't one ), and it's likely to take a process of trial and error for you to find the best performance/price solution.
The Extremis is a decent enough midwoofer that there are several designs by RAW Acoustics, using it in TM/TMM/ MTM configurations; several in fact with WR & dome or ribbon tweeters. I've heard most of these models, and any one of them is more speaker than I need, particularly in the bottom - I honestly doubt the need for a sub, but Cal would probably argue that one.
So, try the FR's in as simple a sealed box as you want - if you roll them off high enough, you can get away with very small sub-enclosure, and still have more than enough room in the same cabinet footprint for whatever midwoofer you choose. For many reasons, I've never been a fan of either BSC EQ, or single bass drivers- even if the latter is only operating for the single lowest octave, which will definitely not be the case in a home theatre situation. Of course with an adequate midbass driver and baffle dimensions, the "step" will be hard to hear.
I don't have the technical expertise to answer your questions regarding flat frequency response, off axis power distribution, etc. ; there should be other contributors who can. But I can tell you that every time I visit the local audio shop where I did most of my shopping over the past 25years, and listen to their hi-end demo systems, with speakers designed by some pretty smart engineers ( B&W, Linn, Magneplanar, Paradigm, Tannoy, Wharfedale) to meet those criteria , I don't get the same goosebumps as from the prosaic 2-way AudioNotes (warts, sticker shock and all)
As to your remarks regarding issues of bipole vs "point source" radiation patterns, you might want to read the documentation attached to the following DIY project - if you're interested in math and measurements, there's a fair bit therein :
http://www.t-linespeakers.org/projects/tlB/index.html
FWIW, I can remember when first wetting my feet in this hobby in the mid 70's, a lot of discussion in commercial and the early "underground hi-end audio press" ( that evolved into Stereophile / Absolute Sound ) on whether the ideal speaker would replicate the real world by emulating an "omni-directional point source, throughout the entire audible range" - the floating pulsating sphere; or the opposite case of a flat monopole "open window". I've heard and owned many wonderful and not-so commercial and amateur designs from both schools of thought.
ABS said:
The best place for the 0.5 driver is always on the back of the cabinet where the 90 degree phase roll is in the shawdow of the cabinet and where it can perfectly* compensate for baffle step... a bipole differs from a proper x.5 way system only in the inductor/HP on the back/0.5 driver. There is only 1 reason to put the 0.5 driver on the front -- and that is so it can be shown off.
*assumes a cabinet with front-to-back symmetry.
A 1,5 way FR system should be quite excellent.
If you want the driver to be at its best, you need to relieve it of handling deep bass.... set the crossover at the BS frequency & bi-amp.
Note that no filter solution ever perfectly compensates for baffle step because it doesn't deal with the ripple. The only true fix is to not have any BS... bipole or x.5 with the 0.5 driver on the back have NO bafflestep*
dave
dave
chrisb said:
here is a better one:
http://p10hifi.net/tlinespeakers/FAL/downloads/Extremis-6.8Data.pdf
dave
Chris:
Yes, I am agreeing with you. Different speakers can provide a different acoustical and emotional experience. Differences in design fundamentals can result in very different outcomes even when using the same drivers. I read that article over at t-linespeakers.org and I'll have to read it again to make sure I got all of it.
At the end of the day, I really like the concept and overall sound of the full range - I just want my cake and to eat it too!
At this point I am going to wait until I get the FR's in house to do some testing with them before I make any decisions about bringing other drivers into the mix . . . Having said that, the Extremis might just be on the short list!
Dave:
Your response is extremely helpful as I am leaning toward some kind of .5 configuration with the FR drivers. Could you please elaborate as to why it isn't good to place the .5 driver on the front baffle? I realize that the low pass filter will likely create some phase shifting - is it this phase shift that you suggest would be compensated for by placing the 0.5 driver on the rear? If so, then what is the impact of the group delay on the low midrange performance? I guess a shallow cabinet would be best to minimize that effect?
I know I have seen a number of 2.5 setups where the .5 driver is on the front baffle. For example, I recently read about this design:
link
And at first glance it seems like it might be good. Note that this is not the speaker I want to build, but the concept could be similar. What are the issues you see/know with this kind of design? In general do you see a problem with a narrow baffle design where both drivers are on the same baffle and the baffle step correction requires a high x-over point on the 0.5 driver? I would guess this could result in a muddying of the low midrange output - am I right? If so, then a wide baffle design with a lower baffle step frequency could be better, no?
I think I just found an article explaining exactly what you are describing - pardon my ignorance here - are you the author of it?
link
Having read the article I am now beginning to "get it" - let's say I put the 0.5 on the rear - does it have to be in the exact opposite position of the 1.0 driver or can I place the driver anywhere I want on the rear baffle and what is the impact of moving that driver up and down the baffle? Also, I would typically want to position the full range driver horizontally off-center to provide an improved baffle diffraction response - how is that dealt with for the .5 driver? Is the .5 also offset and if so is it to the same side or the opposite side?
Thanks in advance.
Andrew
Yes, I am agreeing with you. Different speakers can provide a different acoustical and emotional experience. Differences in design fundamentals can result in very different outcomes even when using the same drivers. I read that article over at t-linespeakers.org and I'll have to read it again to make sure I got all of it.
At the end of the day, I really like the concept and overall sound of the full range - I just want my cake and to eat it too!
At this point I am going to wait until I get the FR's in house to do some testing with them before I make any decisions about bringing other drivers into the mix . . . Having said that, the Extremis might just be on the short list!
Dave:
Your response is extremely helpful as I am leaning toward some kind of .5 configuration with the FR drivers. Could you please elaborate as to why it isn't good to place the .5 driver on the front baffle? I realize that the low pass filter will likely create some phase shifting - is it this phase shift that you suggest would be compensated for by placing the 0.5 driver on the rear? If so, then what is the impact of the group delay on the low midrange performance? I guess a shallow cabinet would be best to minimize that effect?
I know I have seen a number of 2.5 setups where the .5 driver is on the front baffle. For example, I recently read about this design:
link
And at first glance it seems like it might be good. Note that this is not the speaker I want to build, but the concept could be similar. What are the issues you see/know with this kind of design? In general do you see a problem with a narrow baffle design where both drivers are on the same baffle and the baffle step correction requires a high x-over point on the 0.5 driver? I would guess this could result in a muddying of the low midrange output - am I right? If so, then a wide baffle design with a lower baffle step frequency could be better, no?
I think I just found an article explaining exactly what you are describing - pardon my ignorance here - are you the author of it?
link
Having read the article I am now beginning to "get it" - let's say I put the 0.5 on the rear - does it have to be in the exact opposite position of the 1.0 driver or can I place the driver anywhere I want on the rear baffle and what is the impact of moving that driver up and down the baffle? Also, I would typically want to position the full range driver horizontally off-center to provide an improved baffle diffraction response - how is that dealt with for the .5 driver? Is the .5 also offset and if so is it to the same side or the opposite side?
Thanks in advance.
Andrew
ABS said:
A 0.5 driver on the front only sorta compensates for baffle step and the roll-off due to the inductor mucks up an octave or 2 above its XO point. A 0.5 driver on the back perfectly compensates for baffle step (actually for perfect the box would need to have no depth, but in practice it is not that critical) and the phase roll of the crossover is in the shadow of the cabinet and has to reach the back wall & come back before it can interfere with the front radiation. If that delay is sufficient the Hass effect makes it immaterial.
Yes... but it is really a condensation of an old thread here.
One of the advantages of the physical arrangement of the driver on the back is that the drivers can be mounted push-push. Force cancelation means that the drivers stay physically motionless in space, vibrations usually transmitted to the box are cancelled and your downward dynamic range is improved.
dave
Okay, I am gradually being persuaded that a bipole design could be the best way for me to proceed. Having mulled this over a bit, here is what I am thinking about doing:
Two FR125's in a bipole configuration both mounted slightly off-axis on their respective baffles and positioned directly in line with one another (front to rear). The rear unit will play only lower frequencies to compensate for baffle step and will probably use a 1st order x-over for rolling off the upper frequency range (this will need to be tested and modeled). The baffle will be as narrow as possible mostly for aesthetic reasons and this will result in a higher cut-off frequency for the rear driver (but that should not be an issue since this is a bipole design).
For enclosure type, I am toying with two ideas:
Option 1 - Using a single sealed enclosure of approximately .25 cu ft for both FR drivers and a second lower chamber of approximately .75 cu ft and ported for a sidefiring subwoofer providing output below 100hz.
Option 2 - Using a 1.0 cu ft ported enclosure for both FR drivers with a downward firing port tuned to around 50 hz.
Option 3 - Add a tweeter to the front FR125 (if needed) in conjunction with 1 and 2.
So here are the questions:
1. For the bipole FR setup, how close can the rear of the enclosure be to a wall and still provide decent sound/imaging? Does the requirement change if the rear driver is just doing BSC versus running full range (also see #2 below)?
2. For the bipole FR setup, what changes in overall system performance should I expect by rolling off the rear firing driver (BSC only) versus running it full range?
3. If I incorporate the sub-woofer into the design would there be any negative impact to its being side fireing? If so, I could possibly consider down firing or front firing but those designs would require a larger front baffle . . .
4. What is the best way to wire the two FR's? Am I correct in thinking that they must be wired in phase to get the push-push/pull-pull operation mode? Do I need to worry about wiring them in parallel versus series - my amps are not 4 ohm stable but I have read that the FR's wired in parallel still have a high enough impedance that amps won't complain?
Thanks.
Andrew
Two FR125's in a bipole configuration both mounted slightly off-axis on their respective baffles and positioned directly in line with one another (front to rear). The rear unit will play only lower frequencies to compensate for baffle step and will probably use a 1st order x-over for rolling off the upper frequency range (this will need to be tested and modeled). The baffle will be as narrow as possible mostly for aesthetic reasons and this will result in a higher cut-off frequency for the rear driver (but that should not be an issue since this is a bipole design).
For enclosure type, I am toying with two ideas:
Option 1 - Using a single sealed enclosure of approximately .25 cu ft for both FR drivers and a second lower chamber of approximately .75 cu ft and ported for a sidefiring subwoofer providing output below 100hz.
Option 2 - Using a 1.0 cu ft ported enclosure for both FR drivers with a downward firing port tuned to around 50 hz.
Option 3 - Add a tweeter to the front FR125 (if needed) in conjunction with 1 and 2.
So here are the questions:
1. For the bipole FR setup, how close can the rear of the enclosure be to a wall and still provide decent sound/imaging? Does the requirement change if the rear driver is just doing BSC versus running full range (also see #2 below)?
2. For the bipole FR setup, what changes in overall system performance should I expect by rolling off the rear firing driver (BSC only) versus running it full range?
3. If I incorporate the sub-woofer into the design would there be any negative impact to its being side fireing? If so, I could possibly consider down firing or front firing but those designs would require a larger front baffle . . .
4. What is the best way to wire the two FR's? Am I correct in thinking that they must be wired in phase to get the push-push/pull-pull operation mode? Do I need to worry about wiring them in parallel versus series - my amps are not 4 ohm stable but I have read that the FR's wired in parallel still have a high enough impedance that amps won't complain?
Thanks.
Andrew