There are a couple of things that go beyond the modeling. The primary purpose of the BSC filter is to being the mid-bass and treble down to the bass below the baffle step. Everybody knows this. One is tempted to use modeled values for the filter and zobel that produce a flat response throughout. Unfortunately, we don't listen on axis. We usually listen anywhere from 10-20* off axis. In the case of the 167E, the treble response tails off significantly at the proper toe-in. To bring up the treble, I omit the zobel. This makes the speaker hot on axis, but right at the proper toe-in.
If your driver is still a bit weak on top without the zobel, you can put a capacitor across the BSC filter. This changes the step filter into a notch filter. This gives, in effect, smiley face equalization. But that's what is needed to get the job done.
Bob
Hi Bob,
I find the subjective high frequency response pretty satisfactory actually, particularly since I tow the speakers in slightly to orient them towards my listening position. (I am really aiming for a limited sweet spot) I've measured the speaker with BSC and done some simulations in spice that show the sort of behavior I would expect. One of my issues is a small listening space with a lot of reflective objects in the way - in the limited measurements I have done so far I have not made any effort to average room response (multiple mic. positions) so some of the measurement issues I am seeing are no doubt due to severe room interactions.
I think your suggestion of boosting the highs for off axis response improvements is interesting and something I will investigate further as I have time.
My two biggest problems are audible colorations and a lack of low end, despite the measurements and the BSC compensation there just is no weight on the bottom end at all. I guess I should have expected that given the tiny driver, lack of excursion capability and the small box. It is all over at 60Hz which is more than a full octave higher than I am used to. (The power amplifier and balance of the electronics are flat to below 20Hz.)
To be fair these are the best sounding diy full ranges I have heard to date, but I built them so I am hardly unbiased..
(Out of 4 or so I have heard to date.) I just want more..
I guess I should 'fess up and admit I am not in any sense a fan of FR speaker systems - these drivers were a birthday present from a close friend and I was intrigued at the challenge of building something decent sounding with them. I think I have succeeded, but I think there is more to be had even given the limitations of the driver and the box design.
I find the subjective high frequency response pretty satisfactory actually, particularly since I tow the speakers in slightly to orient them towards my listening position. (I am really aiming for a limited sweet spot) I've measured the speaker with BSC and done some simulations in spice that show the sort of behavior I would expect. One of my issues is a small listening space with a lot of reflective objects in the way - in the limited measurements I have done so far I have not made any effort to average room response (multiple mic. positions) so some of the measurement issues I am seeing are no doubt due to severe room interactions.
I think your suggestion of boosting the highs for off axis response improvements is interesting and something I will investigate further as I have time.
My two biggest problems are audible colorations and a lack of low end, despite the measurements and the BSC compensation there just is no weight on the bottom end at all. I guess I should have expected that given the tiny driver, lack of excursion capability and the small box. It is all over at 60Hz which is more than a full octave higher than I am used to. (The power amplifier and balance of the electronics are flat to below 20Hz.)
To be fair these are the best sounding diy full ranges I have heard to date, but I built them so I am hardly unbiased..
(Out of 4 or so I have heard to date.) I just want more.. I guess I should 'fess up and admit I am not in any sense a fan of FR speaker systems - these drivers were a birthday present from a close friend and I was intrigued at the challenge of building something decent sounding with them. I think I have succeeded, but I think there is more to be had even given the limitations of the driver and the box design.
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Forgive me it I have this wrong -- you have 167E in HCC's? My experience is that the BVR's have better presence than MLTL's, but MLTL's have better bass. The FT-1600 definitely does 40Hz. My favorite demo is the Bach "Toccata in d". The bottom of the opening descending passage bottoms out 37Hz, and it is there is spades.
Bob
Comments and Questions on FE167 Driver Mods Anyone?
The presence actually is pretty good, and they sound ok at lower volumes (background) and with material that is not too complex or electronic in nature.
The bass such as it is, is very well controlled - there just isn't much going on below 60Hz (where it is down 5dB from midband) I'm being kind setting my FR limits at +/-5dB.
I should probably put some serious effort into breaking them in. Sine or pink noise, any difference? - noting that input power will limited to about 1W. Rated Xmax is only 0.2mm (is that a typo?) - any idea of the maximum safe excursion before damage occurs? (Based on observation on material with a lot of LF an excursion of several mm is quite possible at modest volumes with no signs of audible distress.)
I find going back and forth between the HCC and the Onkens quite jarring actually - I get comfortable with one, and then have to get used to the difference when I go to the other, I will say getting reused to the Onkens is very much easier particularly on any material with significant LF content.
I'm probably being unreasonable, I've heard two other FR designs based on the FE167 and they were quite terrible sounding. One was a build based on the stock Fostex box design and the other a diy design with the port on the back. Neither was using BSC and used well broken in stock FE167. My HCC are actually quite listenable - I am aware of their short comings but in a vacuum (no point of reference - not outer space.. )they would probably be acceptable in most less critical applications.
Has anyone had particular success in taming the high Q resonances in the FE167 whizzer by treating it with puzzle coat or similar? Or foam damping the edge of the whizzer? Are there other tweaks I should perhaps consider. (Note that I don't really have the requisite patience to EnabL these drivers, although anything applied to these cones probably has a significant effect even if it is difficult to measure. )
Anyone think these drivers are a bit colored sounding and if so what did you do in order to tweak their performance?
I know that the word on the street is that these drivers take 100 hrs or greater to break in fully. Beyond the changing compliance in the spider and surround what possible other changes could there be that would improve the sonics of this driver? (Beyond compliance changes does anything happen to the spider or cone in this driver??) Can I really expect a significant improvement or is it that most listeners get used to the quirks of their particular speaker system over that time period?
The presence actually is pretty good, and they sound ok at lower volumes (background) and with material that is not too complex or electronic in nature.
The bass such as it is, is very well controlled - there just isn't much going on below 60Hz (where it is down 5dB from midband) I'm being kind setting my FR limits at +/-5dB.
I should probably put some serious effort into breaking them in. Sine or pink noise, any difference? - noting that input power will limited to about 1W. Rated Xmax is only 0.2mm (is that a typo?) - any idea of the maximum safe excursion before damage occurs? (Based on observation on material with a lot of LF an excursion of several mm is quite possible at modest volumes with no signs of audible distress.)
I find going back and forth between the HCC and the Onkens quite jarring actually - I get comfortable with one, and then have to get used to the difference when I go to the other, I will say getting reused to the Onkens is very much easier particularly on any material with significant LF content.
I'm probably being unreasonable, I've heard two other FR designs based on the FE167 and they were quite terrible sounding. One was a build based on the stock Fostex box design and the other a diy design with the port on the back. Neither was using BSC and used well broken in stock FE167. My HCC are actually quite listenable - I am aware of their short comings but in a vacuum (no point of reference - not outer space..
)they would probably be acceptable in most less critical applications.Has anyone had particular success in taming the high Q resonances in the FE167 whizzer by treating it with puzzle coat or similar? Or foam damping the edge of the whizzer? Are there other tweaks I should perhaps consider. (Note that I don't really have the requisite patience to EnabL these drivers, although anything applied to these cones probably has a significant effect even if it is difficult to measure. )
Anyone think these drivers are a bit colored sounding and if so what did you do in order to tweak their performance?
I know that the word on the street is that these drivers take 100 hrs or greater to break in fully. Beyond the changing compliance in the spider and surround what possible other changes could there be that would improve the sonics of this driver? (Beyond compliance changes does anything happen to the spider or cone in this driver??) Can I really expect a significant improvement or is it that most listeners get used to the quirks of their particular speaker system over that time period?
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Sine waves predominately just works the suspension while pink noise works the entire driver since it's akin to music. Brown noise is for when time is of the essence, but probably too brutal for most 'FR' drivers, so normally limited to sub drivers.
Me I'm impatient, so use pink noise with a 1000 W blower when I don't have Hotlanta's summer noonday heat to do it. Knocks the starch right out of a spider and softens some glues enough to allow dynamic acoustic realignment...........
GM
Me I'm impatient, so use pink noise with a 1000 W blower when I don't have Hotlanta's summer noonday heat to do it. Knocks the starch right out of a spider and softens some glues enough to allow dynamic acoustic realignment...........
GM
Hi GM,
Can you elaborate, because what you describe is probably at the root of most of my issues.
I guess the $0.98 tweak is adding a little foam around the edge of the whizzer cone a la Wharfedale? Can you elaborate on the "kneading the rim" process?
The phase plugs helped a fair amount.
I am going to set up to do some longer term burn in with band limited pink noise when I have some spare time.
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Greets!
Should be able to find plenty of posts about it in a forum search, but basically it's foam/whatever works best packed around the whizzer/cone junction to attenuate both the HF 'hot spot' a glue joint typically creates if not damped at the factory as well as the relatively massive reflections between the two.
'Kneading' is just as it seems, simply using your fingers to work the starch out of the ~first third to half of the whizzer's bell, so something you do a little at a time, though if you overdo it you can always get it back with spray starch, or as some of us have done, use hairspray as a fine tuning method to wind up somewhere in between.
GM
Should be able to find plenty of posts about it in a forum search, but basically it's foam/whatever works best packed around the whizzer/cone junction to attenuate both the HF 'hot spot' a glue joint typically creates if not damped at the factory as well as the relatively massive reflections between the two.
'Kneading' is just as it seems, simply using your fingers to work the starch out of the ~first third to half of the whizzer's bell, so something you do a little at a time, though if you overdo it you can always get it back with spray starch, or as some of us have done, use hairspray as a fine tuning method to wind up somewhere in between.
GM
A light coating of thinned ModPodge on the whizzer and the cone flattened out the top end of my FE166E's quite significantly. Lots of break-in time may have helped, too.
I haven't done any other tweaks to my 166's yet, but my usual routine would be to damp the baskets with duct seal, and ground the basket to the negative terminal. I don't know why the latter would work, but it it seems to do something good to me. Probably a placebo...
Colored? Yeah, I think that goes with the full-ranger territory. You have to either like the sound or not. If you have to fight the natural character of the driver too hard to make it work for you, why bother? I keep playing with them because they bring the best out of my low-powered tube amp, and that amp sounds better than anything else I own.
All JMHO, of course.
Bill
Thanks guys! I'll keep plugging away at this.. Break in, modpodge, and the $0.98 tweak are all on the list of things to try.
Dave - thanks for the great illustration! I'm going to start with GM's advice on break-in and crank up some hours.. Lousymusician's post confirms that specific improvements in my area of concern are possible as well.
I can accept some level of coloration, by definition some speakers are better or worse than others, but there is no perfect transducer.. I'm just trying to get rid of the really obvious deficiencies and buzzing whizzers really have to exist pretty near the top of that list , before I make any judgement about how I feel about FR speakers. The FE167 is not very expensive nor probably even close to representative of the best FR drivers when compared to Feastrex or even some of the other Fostex drivers out there. I hear some promise and I just want to make them as good as I possibly can by both the subjective and objective metrics I generally employ.
I have mentioned that I am not a big fan of FR speaker systems, but by the same token I am not closed minded either. I believe with certain constraints they can be made to perform quite well. I have been told repeatedly by other 'experts' that this, that or the other thing couldn't possibly sound good - only to have to tell them that the amplifier or pre-amp they extolled as being one of the best they have ever heard uses the despised technology they expounded on. One of the recent discussions I was involved in had me defending FR speakers systems as a viable choice to one such naysayer.. So even though I embarked on this project for my own personal reasons (the need for a challenging project where I might learn something, and a good pair of gifted full range drivers) I hope to show that this can quite good with some often missed attention to detail. If nothing else I am learning and having fun which was the point.
Also this has been a real bargain in terms of expense. My total outlay excluding my father in laws time (a gift) has been less than $100 - despite the issues I've written about so far I can't imagine getting anything in this league for that kind of money. So it is quite cost effective even if you had to pay for the drivers which I didn't. They definitely have high bang for the buck which Onkens definitely don't. (They eventually exceeded expectations with a little tweaking, but were very expensive to build.)
Dave - thanks for the great illustration! I'm going to start with GM's advice on break-in and crank up some hours.. Lousymusician's post confirms that specific improvements in my area of concern are possible as well.
I can accept some level of coloration, by definition some speakers are better or worse than others, but there is no perfect transducer.. I'm just trying to get rid of the really obvious deficiencies and buzzing whizzers really have to exist pretty near the top of that list
, before I make any judgement about how I feel about FR speakers. The FE167 is not very expensive nor probably even close to representative of the best FR drivers when compared to Feastrex or even some of the other Fostex drivers out there. I hear some promise and I just want to make them as good as I possibly can by both the subjective and objective metrics I generally employ. I have mentioned that I am not a big fan of FR speaker systems, but by the same token I am not closed minded either. I believe with certain constraints they can be made to perform quite well. I have been told repeatedly by other 'experts' that this, that or the other thing couldn't possibly sound good - only to have to tell them that the amplifier or pre-amp they extolled as being one of the best they have ever heard uses the despised technology they expounded on. One of the recent discussions I was involved in had me defending FR speakers systems as a viable choice to one such naysayer..
So even though I embarked on this project for my own personal reasons (the need for a challenging project where I might learn something, and a good pair of gifted full range drivers) I hope to show that this can quite good with some often missed attention to detail. If nothing else I am learning and having fun which was the point. Also this has been a real bargain in terms of expense. My total outlay excluding my father in laws time (a gift) has been less than $100 - despite the issues I've written about so far I can't imagine getting anything in this league for that kind of money. So it is quite cost effective even if you had to pay for the drivers which I didn't. They definitely have high bang for the buck which Onkens definitely don't. (They eventually exceeded expectations with a little tweaking, but were very expensive to build.)
Wondering whether you are using BSC with your HCC? Based on listening and measurements I find it indispensable.
There has been some progress with the whizzer issues I have been having. Last night I teased out some acoustical batting into a long thin bundle of threads and loosely wrapped it around the whizzer and the cone. To say it made a difference was an understatement, at first I thought most of the highs went along with the sibilance and odd high frequency rubbish I was hearing, then I started to notice that things that sounded somewhat lost before like a brush on a cymbal were for the first time clearly audible.
I've got some felt I am going to try in on the angled portion of the BVR horn section to see if I can get a little additional attenuation of HF radiation out of the port. It's pretty far down, but not entirely gone and I don't want to over damp the interior of the cabinet as it sounds quite ok in the midrange.
(not over damped)
Last night I filled the gap between the magnet assembly and the basket, it might have made some difference, but it was not pronounced in the way damping the whizzer cone was.
I've spent a number of hours listening and tweaking this afternoon along with an interlude of burn-in with pink noise. Damping the whizzer with the acoustic batting material I mentioned in my previous post has made a world of difference - all sorts of HF detail that was completely masked by the whizzer cone resonances is now very audible. The resonances I complained about at normal listening levels are now completely suppressed, although I have to do another sweep to assess the improvement it is not hard to hear the difference.
I also felted the mouth of BVR as you will see in the attached photograph - this made an audible difference and reduced the radiation of unwanted mid frequencies from the port into the room. The felt was purchased in the crafts department of the local wally world and cost 37 cents a sheet - cheap and effective. (I think the damping in the box is just about right so even though adding more would have further reduced stuff getting through the port slot I was concerned that adding more material would deaden the midrange from the driver too much.)
I am also attaching two pictures that show the acoustic batting material installed around the back side of the whizzer cone - it is barely visible and is extremely effective.
I should mention all of the sibilance was abruptly eliminated with the whizzer tweak, and I am not aware of any deficit in the high frequency response.
I will remeasure the response within a few days and post once I am sure I have something reasonable to share.
What I can say is that the HCC have become quite a bit more listenable, and I am actually enjoying them now which was not really the case before.
Bass is improving a little at a time, I don't expect stellar extension, but it would be great if I could get to 55Hz or so once the drivers are fully broken in.
The sweet spot is quite narrow, and the whizzers do beam quite noticeably, but outside of the sweetspot the subjective HF balance remains quite good (undoubtedly due to the phase plugs) so I doubt I will need to fiddle too much with the BSC for the time being. Given how I use them definitely don't want to employ any HF boost to increase response off axis - the tonal balance seems like a good overall compromise at this point.
So if I were to rank the relative importance of the tweaks I've done so far I would say:
I also felted the mouth of BVR as you will see in the attached photograph - this made an audible difference and reduced the radiation of unwanted mid frequencies from the port into the room. The felt was purchased in the crafts department of the local wally world and cost 37 cents a sheet - cheap and effective. (I think the damping in the box is just about right so even though adding more would have further reduced stuff getting through the port slot I was concerned that adding more material would deaden the midrange from the driver too much.)
I am also attaching two pictures that show the acoustic batting material installed around the back side of the whizzer cone - it is barely visible and is extremely effective.
I should mention all of the sibilance was abruptly eliminated with the whizzer tweak, and I am not aware of any deficit in the high frequency response.
I will remeasure the response within a few days and post once I am sure I have something reasonable to share.
What I can say is that the HCC have become quite a bit more listenable, and I am actually enjoying them now which was not really the case before.
Bass is improving a little at a time, I don't expect stellar extension, but it would be great if I could get to 55Hz or so once the drivers are fully broken in.
The sweet spot is quite narrow, and the whizzers do beam quite noticeably, but outside of the sweetspot the subjective HF balance remains quite good (undoubtedly due to the phase plugs) so I doubt I will need to fiddle too much with the BSC for the time being. Given how I use them definitely don't want to employ any HF boost to increase response off axis - the tonal balance seems like a good overall compromise at this point.
So if I were to rank the relative importance of the tweaks I've done so far I would say:
- Whizzer damping tweak
- BSC
- Phase plugs
- Felted BVR port
Attachments
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Breaking all the rules.. I'm listening to Janacek's "Sinfonietta" and am quite pleased with what I am hearing. Nice, obviously not a huge amount of bottom end, but otherwise there is a nice level of detail, subjectively smooth tonal balance, very good dynamics, no hint of congestion or other problems - a big improvement. More hours of listening needed, but I can probably just listen to them now and wait for the rest of the break in to occur..
FWIW I think many comments about the FR being particularly suited to some types of music might be a function of some of the issues I have struggled through (not being addressed) because at this point they seem to be doing fine on just about everything I throw at them.
Last night I was listening to some "pop" which shall remain nameless, and that sounded quite credible as well.
Everything I do needs to perform credibly on any type of material or I can't accept it - anything else to me talks of a shortcoming unaddressed or a misapplication whether deliberate or otherwise..
I will post some FR measurements when I have made some new measurements. I wish I had done some impulse measurements as I suspect the before and after measurements would be interesting.
FWIW I think many comments about the FR being particularly suited to some types of music might be a function of some of the issues I have struggled through (not being addressed) because at this point they seem to be doing fine on just about everything I throw at them.
Last night I was listening to some "pop" which shall remain nameless, and that sounded quite credible as well.
Everything I do needs to perform credibly on any type of material or I can't accept it - anything else to me talks of a shortcoming unaddressed or a misapplication whether deliberate or otherwise..
I will post some FR measurements when I have made some new measurements. I wish I had done some impulse measurements as I suspect the before and after measurements would be interesting.
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I've appreciated all of the help and encouragement I've received on this project..
I'm enjoing Midori right now.. Violin sounds good, just the right amount of rosin in the bowing, piano sounds natural.
I listen to all sorts of stuff, tomorrow I am just as likely to be listening to XTC or Crystal Method..
One thing I didn't mention before is they do seem able to produce a very large sound stage and fill this room very effectively which while not huge is big enough that they could sound a bit lost in here. (Great because the other room they will be used in is a bit larger overall.) Small driver, but nothing small about the sound.
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Argh, Tweaks Galore...
I took the drivers out tonight and added another layer of batting - I think it helped a little as the mids seem a bit too hot compared to the now tamed highs and the low end.
Also felted the brace as I am wondering about diffraction etc off of those sharp edges right behind the speaker cone.
I think these helped slightly seems like an improvement. I'm concerned about getting carried away and over damping the speakers - so far this doesn't seem to be an issue.
I've run them with pink noise for about 2 1/2 hrs over the last few days and managed about another 4 hrs of listening.
There is plenty of detail, sound overall is rather light weight despite the rather pronounced level of BSC I am using. Conclusion is that for any real bass these will probably need a subwoofer, which isn't unfortunately in the cards for the moment. There is still something going on - perhaps cone break up or something that seems to be excited rarely but is rather obvious when it happens - have not pinned that down - will probably turn out to be amplifier clipping or something equally embarrassing..
The HCC are about 10dB less efficient than the Onkens so it could be that I am just pushing the amp too hard.
I took the drivers out tonight and added another layer of batting - I think it helped a little as the mids seem a bit too hot compared to the now tamed highs and the low end.
Also felted the brace as I am wondering about diffraction etc off of those sharp edges right behind the speaker cone.
I think these helped slightly seems like an improvement. I'm concerned about getting carried away and over damping the speakers - so far this doesn't seem to be an issue.
I've run them with pink noise for about 2 1/2 hrs over the last few days and managed about another 4 hrs of listening.
There is plenty of detail, sound overall is rather light weight despite the rather pronounced level of BSC I am using. Conclusion is that for any real bass these will probably need a subwoofer, which isn't unfortunately in the cards for the moment. There is still something going on - perhaps cone break up or something that seems to be excited rarely but is rather obvious when it happens - have not pinned that down - will probably turn out to be amplifier clipping or something equally embarrassing..
The HCC are about 10dB less efficient than the Onkens so it could be that I am just pushing the amp too hard.
Actually the changes I've made do seem to be an improvement, the sound overall is a little less bright, and better balanced.. There also seems to be a bit more depth. Suprisingly there seems to be a little more bass although that might be a function of the spls (loud) or perhaps I have added enough stuffing that due to the added resistance at LF the box is starting to look a bit bigger??
Or they're breaking in... Idle speculation...
Or they're breaking in... Idle speculation...
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