PERSONAL EXPERIMENT OBJECTIVES
1. Only one pair of enclosures will be made.
2. Small single fullrange drivers will be used.
3. Starting with the smallest of 4 chosen drivers, the limits of the drivers will be tested in terms of displacement limited spl and overall sound quality in order to determine if a small driver can be used without a sub in a small bedroom or tv (NOT HT) system.
4. The enclosures will be BIB inspired pipe/horns to achieve maximum bass potential and will be sized such that the enclosures strech the limits of the drivers I have on hand but if this proves to be the case, at least 2 other affordable driver options are readily available, which may prove more suitable.
THE DRIVERS
I already have the fostex 108e sigma and 126e but if the box proves to be too large for these, the 127e or pioneer a11 will definitely work. I won't be buying the 127 or a11 if one of the drivers I have onhand works well.
Recommended BIB mouth sizes for these drivers are as follows:
108 - 33 inches
126 - 63 inches (could be happy with less)
127 - 63 inches (could be happy with more)
a11 - 60 inches (could be happy with more, probably a good bit more)
- all drivers have ~70 hz fs, except the 108, which is 77
THE ENCLOSURES
- BIB inspired pipe/horn - inverted and back firing
- line length - 95.5 inches (this is a stretch for the 108 but all other drivers will find it almost ideal)
- flare - conical expansion starting from a point
- mouth size as built - 81 inches (this is a big stretch for the 108, less so for some of the others)
- driver position - .417 x line length, centered about 42 inches up from the floor
THE COMPETITION
I have been using a buddy's fonken style ported box to break in the 108's. It's hardly a fair fight, but these serve perfectly for a reference point. The box is 5 liters and response is pictured below (corner loaded for easy reference with the corner loaded pipe/horn below)
And just for reference, this is the new pipe/horn assuming an end loaded driver (the 108). Hornresp can't sim the driver position I use so the graphs don't mean much but certain info can be inferred. Like the fact that this has WAY more gain than the ported box above. (And less excursion too) But it's also almost 10x larger.
STAGE ONE
I only have enough clamps to make one at a time, so initial impressions consisted of a/b testing the 108 in the ported box vs the 108 in the first completed but UNSTUFFED pipe/horn.
The ported box sounds like a decent (but bass shy) mini should. Maybe a bit bright. On the other hand the pipe/horn had WAY more (sometimes almost unbelieveable) bass, but muddy midbass/low mids. Definitely not bright anymore. Kind of hollow or boxy sounding. Clearly a lot of stuffing needed. And unfortunately I'm already doubting the ability of the 108 to produce satisfying spl without a sub. Not really a surprise though.
STAGE TWO
A few hours later, the other box was ready, so I added it to the system with the first pipe/horn and added stuffing to both - maybe about 225 cubic inches of fibreglass insulation stuffed through the driver hole and spread around as well as possible.
With stuffing the overall tone improved greatly, but still muddy sounding in places. The bass was still incredible (for a 4 inch driver, that is) and bass response is flatter, but not quite strong enough for my taste (until around fs, where performance is still pronounced), the box sounds like it's tuned too low for this driver. And the max spl is clearly not enough for even a secondary small system without a sub. (IMO) Almost but not quite.
I could try to improve the overall sound with the 108 but displacement is the main issue here. The 108 is out.
STAGE THREE
Sub in the 126. For some reason I did not think the 126 would require as much stuffing so I removed half of what was in there.
Immediately the sound was much better, the 126 matched the size and tuning of the boxes very well (as far as I can tell so far). Almost surprising how natural, balanced and musical it sounds, no more obvious midrange bloat, and it probably does not need any more stuffing. Time will tell, and I was mainly interested in testing max bass spl in the single short listening session I have had so far.
The 126 did seem to have much more max bass potential than the 108. It seemed substantial. It is actually incredible considering the fact that the driver has only 65 sq cm of cone area, but at the same time I am not 100 percent sure yet if the amount of bass justifies the size and weight of the boxes. They are fairly large. And costly too, if premium material is used. OTOH, if this can be overlooked, these now seem to be very close to being everything I need from a small secondary system in terms of bass extension and max spl.
As I said though, I only had about 1 hour with these speakers with the 126 so far, so things could change at any time.
STAGE FOUR
Has not happened yet. Next up I need to listen a lot more and adjust stuffing to taste by ear. Once that is done, I need to measure how low these actually go. At the same time, I can determine if the 126 is ideal or if one of the other remaining 2 drivers (which prefer larger enclosures) would be a happier match. If there is a significant bump (increased spl) at the tuning frequency (fundamental harmonic) then I can safely use one of the other drivers, and maybe even get a bit more bass. The pioneer a11 has WAY more rated xmax, but not sure now much more in real life, since the 126 can obviously go way more than it's rated xmax.
CONCLUSION
(So far) At first glance, it seems that the 108 can't be stretched as far as I'd like. And there are displacement issues.
When using the 126 I am very surprised at how little stuffing it seems to need. And how balanced it sounds in terms of frequency response.
When using the 126 the bass output is phenomenal when compared to other optional enclosures for the same driver. But is it worth the size and weight? Could a frugal horn do just about the same thing in half the size? Not sure yet.
At this point it is undetermined whether I would be satisfied with this speaker without a subwoofer in a small secondary system over the long term. But I am absolutely certain that the 8 inch 206 in a BIB inspired pipe/horn could easily be enough, and might even be good enough to pull it's weight in a nice primary stereo system. I was worried that BIB and other style pipe horns might have unacceptable frequency response through the lower midbass to upper mids. It doesn't seem to be a concern with my second choice of drivers (the 108 was not so good, but probably due to the box more than anything else)
I see no reason not to proceed with the 206 project next, as I would already consider this project a success, although it needs much more scrutiny.
Pics and more enclosure details to come, maybe tomorrow.
1. Only one pair of enclosures will be made.
2. Small single fullrange drivers will be used.
3. Starting with the smallest of 4 chosen drivers, the limits of the drivers will be tested in terms of displacement limited spl and overall sound quality in order to determine if a small driver can be used without a sub in a small bedroom or tv (NOT HT) system.
4. The enclosures will be BIB inspired pipe/horns to achieve maximum bass potential and will be sized such that the enclosures strech the limits of the drivers I have on hand but if this proves to be the case, at least 2 other affordable driver options are readily available, which may prove more suitable.
THE DRIVERS
I already have the fostex 108e sigma and 126e but if the box proves to be too large for these, the 127e or pioneer a11 will definitely work. I won't be buying the 127 or a11 if one of the drivers I have onhand works well.
Recommended BIB mouth sizes for these drivers are as follows:
108 - 33 inches
126 - 63 inches (could be happy with less)
127 - 63 inches (could be happy with more)
a11 - 60 inches (could be happy with more, probably a good bit more)
- all drivers have ~70 hz fs, except the 108, which is 77
THE ENCLOSURES
- BIB inspired pipe/horn - inverted and back firing
- line length - 95.5 inches (this is a stretch for the 108 but all other drivers will find it almost ideal)
- flare - conical expansion starting from a point
- mouth size as built - 81 inches (this is a big stretch for the 108, less so for some of the others)
- driver position - .417 x line length, centered about 42 inches up from the floor
THE COMPETITION
I have been using a buddy's fonken style ported box to break in the 108's. It's hardly a fair fight, but these serve perfectly for a reference point. The box is 5 liters and response is pictured below (corner loaded for easy reference with the corner loaded pipe/horn below)
An externally hosted image should be here but it was not working when we last tested it.
And just for reference, this is the new pipe/horn assuming an end loaded driver (the 108). Hornresp can't sim the driver position I use so the graphs don't mean much but certain info can be inferred. Like the fact that this has WAY more gain than the ported box above. (And less excursion too) But it's also almost 10x larger.
An externally hosted image should be here but it was not working when we last tested it.
STAGE ONE
I only have enough clamps to make one at a time, so initial impressions consisted of a/b testing the 108 in the ported box vs the 108 in the first completed but UNSTUFFED pipe/horn.
The ported box sounds like a decent (but bass shy) mini should. Maybe a bit bright. On the other hand the pipe/horn had WAY more (sometimes almost unbelieveable) bass, but muddy midbass/low mids. Definitely not bright anymore. Kind of hollow or boxy sounding. Clearly a lot of stuffing needed. And unfortunately I'm already doubting the ability of the 108 to produce satisfying spl without a sub. Not really a surprise though.
STAGE TWO
A few hours later, the other box was ready, so I added it to the system with the first pipe/horn and added stuffing to both - maybe about 225 cubic inches of fibreglass insulation stuffed through the driver hole and spread around as well as possible.
With stuffing the overall tone improved greatly, but still muddy sounding in places. The bass was still incredible (for a 4 inch driver, that is) and bass response is flatter, but not quite strong enough for my taste (until around fs, where performance is still pronounced), the box sounds like it's tuned too low for this driver. And the max spl is clearly not enough for even a secondary small system without a sub. (IMO) Almost but not quite.
I could try to improve the overall sound with the 108 but displacement is the main issue here. The 108 is out.
STAGE THREE
Sub in the 126. For some reason I did not think the 126 would require as much stuffing so I removed half of what was in there.
Immediately the sound was much better, the 126 matched the size and tuning of the boxes very well (as far as I can tell so far). Almost surprising how natural, balanced and musical it sounds, no more obvious midrange bloat, and it probably does not need any more stuffing. Time will tell, and I was mainly interested in testing max bass spl in the single short listening session I have had so far.
The 126 did seem to have much more max bass potential than the 108. It seemed substantial. It is actually incredible considering the fact that the driver has only 65 sq cm of cone area, but at the same time I am not 100 percent sure yet if the amount of bass justifies the size and weight of the boxes. They are fairly large. And costly too, if premium material is used. OTOH, if this can be overlooked, these now seem to be very close to being everything I need from a small secondary system in terms of bass extension and max spl.
As I said though, I only had about 1 hour with these speakers with the 126 so far, so things could change at any time.
STAGE FOUR
Has not happened yet. Next up I need to listen a lot more and adjust stuffing to taste by ear. Once that is done, I need to measure how low these actually go. At the same time, I can determine if the 126 is ideal or if one of the other remaining 2 drivers (which prefer larger enclosures) would be a happier match. If there is a significant bump (increased spl) at the tuning frequency (fundamental harmonic) then I can safely use one of the other drivers, and maybe even get a bit more bass. The pioneer a11 has WAY more rated xmax, but not sure now much more in real life, since the 126 can obviously go way more than it's rated xmax.
CONCLUSION
(So far) At first glance, it seems that the 108 can't be stretched as far as I'd like. And there are displacement issues.
When using the 126 I am very surprised at how little stuffing it seems to need. And how balanced it sounds in terms of frequency response.
When using the 126 the bass output is phenomenal when compared to other optional enclosures for the same driver. But is it worth the size and weight? Could a frugal horn do just about the same thing in half the size? Not sure yet.
At this point it is undetermined whether I would be satisfied with this speaker without a subwoofer in a small secondary system over the long term. But I am absolutely certain that the 8 inch 206 in a BIB inspired pipe/horn could easily be enough, and might even be good enough to pull it's weight in a nice primary stereo system. I was worried that BIB and other style pipe horns might have unacceptable frequency response through the lower midbass to upper mids. It doesn't seem to be a concern with my second choice of drivers (the 108 was not so good, but probably due to the box more than anything else)
I see no reason not to proceed with the 206 project next, as I would already consider this project a success, although it needs much more scrutiny.
Pics and more enclosure details to come, maybe tomorrow.
I really like your thinking on this. I am also looking into some bibs for the A11 as well as a few other small drivers. Please keep us posted on your progress.
I do have a few questions though.
1.) Are the cabs positioned in corners?
2.) Are you optimising positions after each speaker swap?(or is it more of an enclosure thing than a driver behaving in an enclosure thing? I don't know)
3.) What kind of basis are you judging "adequate" bass performance? I know this is subjective, but just try and get me in the ballpark. You remarked that a 206 "may" perform well enough for a main system. Were you thinking in terms of output or bass quality? What kind of system are you benchmarking this against?
4.) Wow, there were a lot of questions in that last one. Sorry. Rest for this round.
5.) How did you arrive at the bib sizes? Just using the bib calculator on the A11(using 70Hz for Fs, 3.66l for Vas and .58 for Qts) I come up with a CSA of 47 sq. in. Is this part of stretching the limits?
I can say that I am very interested in what you find. Thanks for posting this.
I do have a few questions though.
1.) Are the cabs positioned in corners?
2.) Are you optimising positions after each speaker swap?(or is it more of an enclosure thing than a driver behaving in an enclosure thing? I don't know)
3.) What kind of basis are you judging "adequate" bass performance? I know this is subjective, but just try and get me in the ballpark. You remarked that a 206 "may" perform well enough for a main system. Were you thinking in terms of output or bass quality? What kind of system are you benchmarking this against?
4.) Wow, there were a lot of questions in that last one. Sorry. Rest for this round.
5.) How did you arrive at the bib sizes? Just using the bib calculator on the A11(using 70Hz for Fs, 3.66l for Vas and .58 for Qts) I come up with a CSA of 47 sq. in. Is this part of stretching the limits?
I can say that I am very interested in what you find. Thanks for posting this.
1. Not only are they in corners right now, but the corners are in a recessed alcove of a very large room. It's a great spot for bass support but not so much for good sound.
2. Not too concerned. Just stick drivers in, make sure they are in phase and somewhat near a corner and they're good to go.
3. In this instance "adequate" levels of bass are purely subjective. It has to be entirely subjective anyway, since I can't acurately measure it. I knew I would need about 50 hz at decent spl to consider it satisfactory and that's why the line length was chosen to be 95.5 (close enough). Ideally I'd like them loud enough to compare favorably with the Technics 3 way ported boxes with 10 inch woofer that used to be in these corners.
When I mentioned the 206 would probably perform well, it was the midrange I was worried about, not the bass. I want speakers with decent sound quality, so this first experiment was to see if I like this style of pipe/horn or not before commiting to the expense of a much larger 206 version. I have no benchmark other than the fact that subjectively I don't think I would mind having the 206 version in my main system, probably mostly without a sub except for HT.
5. Where did you get your specs? I'm looking at the partsexpress a11 page and it says fs 70, qts .35, vas .31 cubic feet (~8.8 liters IIRC). Put these numbers into the BIB_166_GM_v2 calculator gives mouth size 60 inches IIRC.
For the other 3 drivers, BIB mouth size was taken from recommended size from zillaspeak.com.
If you look at the designs at zillaspeak you can see that several of the drivers have 2 recommended sizes, the size the calculator outputs and the "more bass" version which is usually about 30 percent larger (mouth). Extrapolating from this, I figure the a11 can handle a mouth size between about 60 - 90 square inches, 90 being the "more bass" version.
They have the measured specs on a link on that page. At the bottom of this page. Aside from the Fs, I belive that these are the specs that have been accepted as closer to "true" though I'm not 100% on that.
I just had an observation on maybe 'cleaning up' the 108 you have.
You mentioned putting the stuffing all around the driver in the peak area. What I've done is pretty much ignore the BIB suggested
stuffing and put some up in the peak and a thin absorption material
behind the driver. I've used billiard felt or a thin piece of foam
in some of my setups. And I think I have to credit GM for this.
The chamfer on the speaker cutout I do every time now.
I have one bib that is slapped together with a 50 cent Pioneer in
the max size cabinet for the FE127e. The specs on this 50 cent
are really low. What is surprising is how much bang for the buck is there. To clean up the low end on it I'm considering doing a 'finished build' to see if that last bit of improvement appears. From the specs, the cabinet size would be dramatically smaller.
You are right about the wood. Top end stuff is a serious investment.
My finished build for the cheapie will be made of scraps.
You mentioned putting the stuffing all around the driver in the peak area. What I've done is pretty much ignore the BIB suggested
stuffing and put some up in the peak and a thin absorption material
behind the driver. I've used billiard felt or a thin piece of foam
in some of my setups. And I think I have to credit GM for this.
The chamfer on the speaker cutout I do every time now.
I have one bib that is slapped together with a 50 cent Pioneer in
the max size cabinet for the FE127e. The specs on this 50 cent
are really low. What is surprising is how much bang for the buck is there. To clean up the low end on it I'm considering doing a 'finished build' to see if that last bit of improvement appears. From the specs, the cabinet size would be dramatically smaller.
You are right about the wood. Top end stuff is a serious investment.
My finished build for the cheapie will be made of scraps.
loninappleton said:
Ignore the suggested damping? You've just described the ~'standard' initial damping strategy for these cabinets. Being chamberless corner horns, they all need a degree of tailoring to room, system & personal preference after that -some will be happy as-is, others will need a light layer on the base etc.
Thanks for the responses guys. I DID realize the specs for the fostex were inaccurate due to conversations here in the past. I DID NOT realize the a11 specs at partsexpress were wrong, and while I am happy that you guys pointed it out I'm not too concerned I am confident that it will like to be in a larger box than the 126 (and hopefully won't be needing it anyway).
I'm sure it can drive that line length, and probably more, but the real issue here is displacement. Like any other speaker system, the lower you tune it the higher displacement requirements get. A ~ 40 hz tuning for a 4.5 inch driver is pushing it a bit. Can it do it? Yes. Can it do it loud? NO.
Lon, I wasn't sure exactly what to do with the stuffing, so I shoved it through the hole and simultaneously shoved it up and over the divider and down into the peak, and just generally spread it everywhere and made a mess. It's probably mostly fallen down into the tip by now, not sure, but it doesn't seem to need much (on first impresssion). More construction details coming when I get the pics.
I'm sure it can drive that line length, and probably more, but the real issue here is displacement. Like any other speaker system, the lower you tune it the higher displacement requirements get. A ~ 40 hz tuning for a 4.5 inch driver is pushing it a bit. Can it do it? Yes. Can it do it loud? NO.
Lon, I wasn't sure exactly what to do with the stuffing, so I shoved it through the hole and simultaneously shoved it up and over the divider and down into the peak, and just generally spread it everywhere and made a mess. It's probably mostly fallen down into the tip by now, not sure, but it doesn't seem to need much (on first impresssion). More construction details coming when I get the pics.
I should probably explain why I made the box so big and seemingly ignored the published recommended mouth sizes.
1. The wood was already cut professionally for an abandoned project so I wanted to use these panels without changing (and messing up) the straight, professional cuts.
2. I like bass and the point of the project is to see if a small driver can be used without a sub, so anything to boost the bass a bit is welcome.
3. Hornresp shows some general trends when it comes to oversizing the box a bit.
a. Excursion goes down.
b. The fundamental harmonic gets stronger.
c. Every harmonic above the fundamental is LESS pronounced.
Put these 3 together and you get more bass with less excursion and less midrange ripple.
4. Putting the driver at ~40 percent line length has some advantages but there are disadvantages as well. Generally weak bass is one of the disadvantages. Making the box bigger can compensate for this somewhat. MJK's alignment tables (attachment B IIRC) shows this brilliantly with pictures.
5. In the end I'd rather be too big than too small. Even if my boxes ended up being too big for any of the 4 drivers of interest, there are countless other 4.5 inch drivers with higher vas and qts and inevitable one of them is going to work. Alternatively, a low q and vas 5.25 could be used for extra spl.
So that's why so big. So far the 126 seems to be a good fit, so maybe all the assumptions here were not too far off.
1. The wood was already cut professionally for an abandoned project so I wanted to use these panels without changing (and messing up) the straight, professional cuts.
2. I like bass and the point of the project is to see if a small driver can be used without a sub, so anything to boost the bass a bit is welcome.
3. Hornresp shows some general trends when it comes to oversizing the box a bit.
a. Excursion goes down.
b. The fundamental harmonic gets stronger.
c. Every harmonic above the fundamental is LESS pronounced.
Put these 3 together and you get more bass with less excursion and less midrange ripple.
4. Putting the driver at ~40 percent line length has some advantages but there are disadvantages as well. Generally weak bass is one of the disadvantages. Making the box bigger can compensate for this somewhat. MJK's alignment tables (attachment B IIRC) shows this brilliantly with pictures.
5. In the end I'd rather be too big than too small. Even if my boxes ended up being too big for any of the 4 drivers of interest, there are countless other 4.5 inch drivers with higher vas and qts and inevitable one of them is going to work. Alternatively, a low q and vas 5.25 could be used for extra spl.
So that's why so big. So far the 126 seems to be a good fit, so maybe all the assumptions here were not too far off.
Scottmoose said:
I apologize if this was confusing.
The pictures at 'Zilla show big wads of stuffing around the driver and up into the peak. For me, the peak and the rear of the driver area are treated separately _plus_ the layer at the bottom.
Then there's the pennant, but all this is in the main BIB thread.
With the cheap Pioneer K1VA8 build I'm thinking of making a removable baffle and just attach the remavable part to corner blocks on the main 2 piece front baffle. This may also give me any wiggle room I need for driver depth. All this remains to be seen.
But the question of accurate numbers from parts express leads me to wonder where I could get good ones for a discontinued item like the Pioneer?
I've done google searches on
K1VA8
and also
10-28LA/XCN
and not found any alternatives.
just a guy said:
Just a note on an alternative.
There's a new Tangband out that's sort of pricey but may fill the
niche of a specification:
http://www.tb-speaker.com/detail/1230_04/w4-1757s.htm
Coming soon to PE.
Here's a couple of pics. Unfortunately I still can't take a good picture to save my life. You can see THE COMPETITION fonken style ported box for reference. Also for size reference, the tv is a 26 inch model. Pipe/horns are fitted with black 126.
NOTES:
- I've made some subs and OB baffles but this is my first pair of real speakers
- these are UNFINISHED (so far) 3/4 baltic birch
- panels were professionally cut (unfortunately not perfectly as I found out)
- no screws or nails used during construction - only wood glue - and no silicone used after construction - doesn't seem to leak anywhere (you can see a screw sticking out of the front panel of one of the speakers, but we needed to do that because at glue time we realized the baffle panel was not straight - standing against the wall too long, it had taken on a bow and we had to forcefully pull it back straight and clamp it tight)
- driver hole is chamfered
- these could look VERY nice if I take the time and money to finish them properly
- ~$80 worth of baltic birch and I paid $20 for the professional cut job, so ~$100 invested in the boxes so far
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
NOTES:
- I've made some subs and OB baffles but this is my first pair of real speakers
- these are UNFINISHED (so far) 3/4 baltic birch
- panels were professionally cut (unfortunately not perfectly as I found out)
- no screws or nails used during construction - only wood glue - and no silicone used after construction - doesn't seem to leak anywhere (you can see a screw sticking out of the front panel of one of the speakers, but we needed to do that because at glue time we realized the baffle panel was not straight - standing against the wall too long, it had taken on a bow and we had to forcefully pull it back straight and clamp it tight)
- driver hole is chamfered
- these could look VERY nice if I take the time and money to finish them properly
- ~$80 worth of baltic birch and I paid $20 for the professional cut job, so ~$100 invested in the boxes so far
STAGE 4
I moved the speakers to a much smaller room (11x14 feet with good corners) and they didn't sound any good in there. Nothing ever does really. I was noticing too much emphasis on some vocals and midbass, so I added stuffing. I wanted to see what it sounded like very well damped so in total there is about 500 cubic inches of fibreglass in each, stuffed from tip to up to the top of the divider board. Sounded a bit better, cleaned up the vocals and diluted the (very) peaky bass somewhat.
Having an idea of what they sound like in that room (crap - but not surprising) I brought them back out into the big room and noticed now that the bass was no longer so peaky there didn't seem to be as much of it. But although bass levels seemed low in spl I was hearing notes in some tracks that I thought were too low to be hearing. So I finally ran some sine sweeps for an idea of frequency response and learned some interesting things.
1. Even though it is very well damped now and voices sound fine, I can clearly hear ragged response in the range I tested (20 - 500 hz, and especially from 160 and up).
2. I was expecting my first 2 major spikes to occur at ~ 50 hz and 170 hz. The signal generator indicates that these peaks are at 40 and 160 hz. Unless I have a strong room resonance at 40 hz, these speakers are tuned at 40.
3. I was hoping the response would be relatively flat between the first two spikes. This is clearly not the case, as I can hear an extended bass shelf type response, dropping rapidly below 160 hz and then evening out several db lower in volume before finally peaking slightly at 40 before rolling off to nothing.
CONCLUSION
Currently testing a baffle step type of eq boosting 150 and down by 6db. Sounds good. Definitely don't notice the ripple as much listening to music as when testing with sine sweeps.
Unfortunately the drivers don't appreciate this bass boost much. They sound fantastic but severely spl limited.
These boxes are clearly too big for the 126, since I can still hear the fundamental peak clearly even when heavily stuffed.
Considering these developments I don't think the 127 or a11 is going to give me the volume I want. I think the css fr125 or wr125 is going to be a better fit. It wants a bigger box than any of the drivers listed and it has 6 mil xbl xmax.
More testing needed...
I moved the speakers to a much smaller room (11x14 feet with good corners) and they didn't sound any good in there. Nothing ever does really. I was noticing too much emphasis on some vocals and midbass, so I added stuffing. I wanted to see what it sounded like very well damped so in total there is about 500 cubic inches of fibreglass in each, stuffed from tip to up to the top of the divider board. Sounded a bit better, cleaned up the vocals and diluted the (very) peaky bass somewhat.
Having an idea of what they sound like in that room (crap - but not surprising) I brought them back out into the big room and noticed now that the bass was no longer so peaky there didn't seem to be as much of it. But although bass levels seemed low in spl I was hearing notes in some tracks that I thought were too low to be hearing. So I finally ran some sine sweeps for an idea of frequency response and learned some interesting things.
1. Even though it is very well damped now and voices sound fine, I can clearly hear ragged response in the range I tested (20 - 500 hz, and especially from 160 and up).
2. I was expecting my first 2 major spikes to occur at ~ 50 hz and 170 hz. The signal generator indicates that these peaks are at 40 and 160 hz. Unless I have a strong room resonance at 40 hz, these speakers are tuned at 40.
3. I was hoping the response would be relatively flat between the first two spikes. This is clearly not the case, as I can hear an extended bass shelf type response, dropping rapidly below 160 hz and then evening out several db lower in volume before finally peaking slightly at 40 before rolling off to nothing.
CONCLUSION
Currently testing a baffle step type of eq boosting 150 and down by 6db. Sounds good. Definitely don't notice the ripple as much listening to music as when testing with sine sweeps.
Unfortunately the drivers don't appreciate this bass boost much. They sound fantastic but severely spl limited.
These boxes are clearly too big for the 126, since I can still hear the fundamental peak clearly even when heavily stuffed.
Considering these developments I don't think the 127 or a11 is going to give me the volume I want. I think the css fr125 or wr125 is going to be a better fit. It wants a bigger box than any of the drivers listed and it has 6 mil xbl xmax.
More testing needed...
Yeah, it takes either a lot of Xmax or a compression chamber to get much LF output from a small, high Fs driver. I recently loaded a several year old pair of FR125S into some older, heavily tweaked RS 40-1354 MLTLs originally tuned to 42 Hz I made for a buddy as a quick way to audition them.
At this tuning they don't have quite the mid-bass 'snap' of the RS, though not surprisingly they perform so much better overall that it's a 'no-brainer' trade-off, being able to play Brian Bromberg's WOOD at ~piano bar levels in a fairly large, open format apartment living/dining/kitchen room.
Tuned to 35 Hz we could even play DSOTM loud enough to make the downstairs neighbors come up to enjoy the moment and be amazed at these pencil thin columns with their tiny drivers overall outperforming their much more expensive name brand consumer speakers.
Unfortunately, at this tuning there were several LF spikes on WOOD and THE VERY BEST OF DIANA KRALL that would bounce the VC off the back plate, so the original tuning was kept since he has no interest in any music genre outside a fairly narrow spectrum of Jazz, Blues.
I'm really impressed with these drivers overall. There seems to be no audible mechanical damage due to both repeated mild bottoming out as I sought its limits or the hard clips it endured with the lower tuning. Apparently the trade-off for having a high Xmax in an otherwise typically constructed small driver is the lack of a rising rate suspension to both provide an audible alarm that its been passed and some protection against a hard clip.
That said, while all the FR plots I've seen of these shows them as dead flat in our acute hearing BW, these have a 'sharpness' that at least for now requires a relatively low Q ~2-4 dB dip (depending on the CD or FM station) centered at 2 kHz that the tweaked 40-1354s didn't need, though I hope to find an acoustic solution over the Winter.
As always though, YMMV.
GM
At this tuning they don't have quite the mid-bass 'snap' of the RS, though not surprisingly they perform so much better overall that it's a 'no-brainer' trade-off, being able to play Brian Bromberg's WOOD at ~piano bar levels in a fairly large, open format apartment living/dining/kitchen room.
Tuned to 35 Hz we could even play DSOTM loud enough to make the downstairs neighbors come up to enjoy the moment and be amazed at these pencil thin columns with their tiny drivers overall outperforming their much more expensive name brand consumer speakers.
Unfortunately, at this tuning there were several LF spikes on WOOD and THE VERY BEST OF DIANA KRALL that would bounce the VC off the back plate, so the original tuning was kept since he has no interest in any music genre outside a fairly narrow spectrum of Jazz, Blues.
I'm really impressed with these drivers overall. There seems to be no audible mechanical damage due to both repeated mild bottoming out as I sought its limits or the hard clips it endured with the lower tuning. Apparently the trade-off for having a high Xmax in an otherwise typically constructed small driver is the lack of a rising rate suspension to both provide an audible alarm that its been passed and some protection against a hard clip.
That said, while all the FR plots I've seen of these shows them as dead flat in our acute hearing BW, these have a 'sharpness' that at least for now requires a relatively low Q ~2-4 dB dip (depending on the CD or FM station) centered at 2 kHz that the tweaked 40-1354s didn't need, though I hope to find an acoustic solution over the Winter.
As always though, YMMV.
GM
Thanks for that insight, GM. Those drivers seem to be an ideal fit at this point.
I've been completely enjoying these speakers as is for a few days now in a family room tv setup (NOT HT) and they are exquisite for this purpose. The midbass and mids seem extraordinarily forward and strong and in yer face, but mostly not in a bad way. The bass that is present is very clear and I've heard these pipe horns can have an OB-like bass sound. I would not disagree and I like this OB-like sound coupled with the monopole punch. No eq or bass boost is needed in the family room tv setup, since mega bass is not required or even wanted when watching relaxing regular tv programming (especially the commercials). OTOH, it runs out of steam quickly when listening to music with the bass turned up ~ flat.
Sooner or later I will have to swap the drivers for the FR(or WR)125 but I will be away for a couple of weeks and then plan to do some more testing before spending money too quickly. First step when I get back will be to measure the 126 ts parameters (my buddy made a measurement jig) and run the correct numbers through the calculator to see how far from ideal these drivers really are for these boxes. I thought the 126 was going to be a good fit but apparently not.
I've been completely enjoying these speakers as is for a few days now in a family room tv setup (NOT HT) and they are exquisite for this purpose. The midbass and mids seem extraordinarily forward and strong and in yer face, but mostly not in a bad way. The bass that is present is very clear and I've heard these pipe horns can have an OB-like bass sound. I would not disagree and I like this OB-like sound coupled with the monopole punch. No eq or bass boost is needed in the family room tv setup, since mega bass is not required or even wanted when watching relaxing regular tv programming (especially the commercials). OTOH, it runs out of steam quickly when listening to music with the bass turned up ~ flat.
Sooner or later I will have to swap the drivers for the FR(or WR)125 but I will be away for a couple of weeks and then plan to do some more testing before spending money too quickly. First step when I get back will be to measure the 126 ts parameters (my buddy made a measurement jig) and run the correct numbers through the calculator to see how far from ideal these drivers really are for these boxes. I thought the 126 was going to be a good fit but apparently not.
While I am still dragging my feet on getting the fostex measurements, I had the great pleasure of auditioning a (single) css fr125. My buddy also brought his p10 recommended fonken box with him. Over about 1 hr, we tried several different combinations and a/b tests, and as you can imagine we didn't listen to any one combination for very long. Below, listed in order of strongest bass to weakest , are the combinations we tried. (Not sure what the p10 fonken tuning is though)
1. inverted bib with css fr125 (optimal bib size for this driver)
2. p10 fonken with css fr125 (sitting on the floor)
3. same inverted bib with fostex 126e (not optimal bib size for this driver)
4. frugal horn with css fr125 (chamber too small for this driver)
5. frugal horn with fostex 108e (chamber too large for this driver)
I have also tried the 108e in a 5 liter box tuned to 50 hz (this tuning is way too low but I had the box, so...), and in the same inverted bib described above.
Our (very quick) impressions are as follows.
1. We were both frankly amazed that the fonken with fr125 and the inverted bib with the fr125 had about the same max volume and overall tone when the bib was about 2 or 2.5 feet away from the corner. When pushed about 1 foot from the corner though, the bib was the clear bass champ, but not by nearly as much as we were expecting. The bib may have been too overdamped though, I had lots of fibreglass in there. The difference between the tiny fonken and the big bib was so subtle, I'm going to check for internal air leaks in the bib, but I don't think I messed up.
2. The p10 fonken sounded incredibly balanced (once moved up to ear height), which by default actually means that we found the bib with fr125 a bit too bass heavy, especially when pushed right back into the corner.
3. We found the inverted bib with fostex 126e a bit thin and bright, especially when compared to the fr125 in the same box. We were amazed (again) to hear how incredibly different the tonal balance is between these 2 brands.
4. The frugal horn (with too small chamber) with the fr125 just sounded weird and bad, with not much bass.
5. The frugal horn with 108e (with too large chamber) sounds thin and hollow with not much bass. (haven't had a chance to tune it yet)
6. From memory, the 108e did not impress much in either the inverted bib or the ported box.
7. Although the fr125 kicked the crap out of the fostex in the bass dept, it suffers (ever so slightly) from air noise. The copper phase plug is not attached to the cone and air is constantly being squeezed in and out of the gap and it's quite audible if you push it hard.
8. And possibly most importantly:
When you want to crank the bass heavy tunes, NONE of these 4 inch drivers wants to rock out with you. In any of the boxes we tested. Not even the fr125 in the bib. For a tv (not HT) setup, or a bedroom system, ok maybe.
At this point, I see no point in optomizing these inverted bibs to any 4 inch driver. IMO there is absolutely no point in making a box for a 4 inch driver as big as these bibs, to achieve such a low tuning.
So this experiment is done. I'll be looking into 6.5, and possibly even 8 inch woofers to fill in these bibs, although for an 8 inch driver to fit in these boxes, it would have to have extraordinarily low q and vas.
1. inverted bib with css fr125 (optimal bib size for this driver)
2. p10 fonken with css fr125 (sitting on the floor)
3. same inverted bib with fostex 126e (not optimal bib size for this driver)
4. frugal horn with css fr125 (chamber too small for this driver)
5. frugal horn with fostex 108e (chamber too large for this driver)
I have also tried the 108e in a 5 liter box tuned to 50 hz (this tuning is way too low but I had the box, so...), and in the same inverted bib described above.
Our (very quick) impressions are as follows.
1. We were both frankly amazed that the fonken with fr125 and the inverted bib with the fr125 had about the same max volume and overall tone when the bib was about 2 or 2.5 feet away from the corner. When pushed about 1 foot from the corner though, the bib was the clear bass champ, but not by nearly as much as we were expecting. The bib may have been too overdamped though, I had lots of fibreglass in there. The difference between the tiny fonken and the big bib was so subtle, I'm going to check for internal air leaks in the bib, but I don't think I messed up.
2. The p10 fonken sounded incredibly balanced (once moved up to ear height), which by default actually means that we found the bib with fr125 a bit too bass heavy, especially when pushed right back into the corner.
3. We found the inverted bib with fostex 126e a bit thin and bright, especially when compared to the fr125 in the same box. We were amazed (again) to hear how incredibly different the tonal balance is between these 2 brands.
4. The frugal horn (with too small chamber) with the fr125 just sounded weird and bad, with not much bass.
5. The frugal horn with 108e (with too large chamber) sounds thin and hollow with not much bass. (haven't had a chance to tune it yet)
6. From memory, the 108e did not impress much in either the inverted bib or the ported box.
7. Although the fr125 kicked the crap out of the fostex in the bass dept, it suffers (ever so slightly) from air noise. The copper phase plug is not attached to the cone and air is constantly being squeezed in and out of the gap and it's quite audible if you push it hard.
8. And possibly most importantly:
When you want to crank the bass heavy tunes, NONE of these 4 inch drivers wants to rock out with you. In any of the boxes we tested. Not even the fr125 in the bib. For a tv (not HT) setup, or a bedroom system, ok maybe.
At this point, I see no point in optomizing these inverted bibs to any 4 inch driver. IMO there is absolutely no point in making a box for a 4 inch driver as big as these bibs, to achieve such a low tuning.
So this experiment is done. I'll be looking into 6.5, and possibly even 8 inch woofers to fill in these bibs, although for an 8 inch driver to fit in these boxes, it would have to have extraordinarily low q and vas.
I know, I know, you said it before, a couple of times. I had to find out how far they could be pushed. My experience with fullrange drivers is just about limited to what you see in this thread so far, so it's all about learning still. I did expect a bit more from the fr125 bib though.
It might have something to do with the style of music we were playing. Much bassier stuff than dsotm. Rock music probably hides the noise much better.
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