The sonic barrier and the fiberglass will both have a tendency to increase the "apparent volume" of an enclosure. The effect is significant in fully stuffed enclosures (such as sealed subwoofer cabinets) where apparent volume increases of up to 20% have been reported. Lining the walls of a cabinet will have much smaller effects and will largely serve to cancel out the volume of the fibers themselves, netting very little increase in apparent volume. If there is any increase in apparent volume, it is considered a desirable trait, as that leaves more volume to be occupied by additional bracing or further absorption materials. Remember, you can always take up excess volume in an enclosure, but can't always create more!
In much the same way, you can always add more series resistance to a woofer to increase the system qtc, but can't always remove it!
In much the same way, you can always add more series resistance to a woofer to increase the system qtc, but can't always remove it!
gtforme00 - your explanation was really helpful. my only speaker reference book is a 1981 radio shack publication by david weems. it has been quite helpful but always left me a little confused on certain matters. with your explanation in mind i will have another look. hopefully this time i'll get it.
also, i should have said i was confused and not said "hard to reconcile" - sorry.
resistors have been ordered (i wish i had seen this thread on inductive vs non inductive resistors earlier). sonic barrier will likely have to wait until the end of the month as i'll need about $90 worth just to cover the sides near the woofers.
is the fiberglass insulation used the kind you can get at home depot? is there a preferred R-value? higher the better?
i am interested in learning how to measure system q. i recently downloaded speaker workshop and am in the early stages familiarizing myself with the software. i am also considering writing my own program in a data acquisition software package i use regularly. that way i can be sure i can really understand what is going on.
r-carpenter. i took a look at your website. that is amazing work.
once again, thanks to everyone for your help. i will post pics here as well as measurements as the work gets done.
also, i should have said i was confused and not said "hard to reconcile" - sorry.
resistors have been ordered (i wish i had seen this thread on inductive vs non inductive resistors earlier). sonic barrier will likely have to wait until the end of the month as i'll need about $90 worth just to cover the sides near the woofers.
is the fiberglass insulation used the kind you can get at home depot? is there a preferred R-value? higher the better?
i am interested in learning how to measure system q. i recently downloaded speaker workshop and am in the early stages familiarizing myself with the software. i am also considering writing my own program in a data acquisition software package i use regularly. that way i can be sure i can really understand what is going on.
r-carpenter. i took a look at your website. that is amazing work.
once again, thanks to everyone for your help. i will post pics here as well as measurements as the work gets done.
Thank you Tim.
Let’s look at this speaker pair from $ point of view. If I am not mistaken, it cost about 2 grand. So the question here is to what extend it should be improved and at what expense?
I would keep away from fiberglass, especially in the ported system. Call me old fashion but I wouldn’t be looking to breath it in, over a long periods of pleasant listening session.
Polyfill or Cotton fill is just safer and there’s no financial reason not to go for it. Fiberglass isn’t free either.
Last thought. It may be easier to build a replacement crossover and swap it in. If you don’t like it you could place the old x-over back (or if you decide to sell the speaker later on). Different sounding speaker doesn’t necessarily mean a better sounding speaker all though I do believe that minor improvements to the cabinet will make it sound more pleasant.
You absolutely have to do one speaker at a time and listen to the results. The speaker with replaced (or improved) x-over will have lower DCR and may sound slightly louder, so for a proper comparison a Radio Shack SPL meter should be used to match within 0.3 db.
I am very curious to the outcome.
Don’t forget to report.
Roman,
Let’s look at this speaker pair from $ point of view. If I am not mistaken, it cost about 2 grand. So the question here is to what extend it should be improved and at what expense?
I would keep away from fiberglass, especially in the ported system. Call me old fashion but I wouldn’t be looking to breath it in, over a long periods of pleasant listening session.
Polyfill or Cotton fill is just safer and there’s no financial reason not to go for it. Fiberglass isn’t free either.
Last thought. It may be easier to build a replacement crossover and swap it in. If you don’t like it you could place the old x-over back (or if you decide to sell the speaker later on). Different sounding speaker doesn’t necessarily mean a better sounding speaker all though I do believe that minor improvements to the cabinet will make it sound more pleasant.
You absolutely have to do one speaker at a time and listen to the results. The speaker with replaced (or improved) x-over will have lower DCR and may sound slightly louder, so for a proper comparison a Radio Shack SPL meter should be used to match within 0.3 db.
I am very curious to the outcome.
Don’t forget to report.
Roman,
sorry about the late reply. experiments have been running overtime at work.
your point about budget is a good one. i purchased these new for $1300 about 6 months ago (late graduation present to myself). i have grown unhappy with how they sound (in other words i've heard speakers since the purchase that i like more). my only option right now is upgrade, as replacement would be too costly. however, i am not sure they will sound the way i like regardless of money invested. i think at this point i am going to proceed with caution. try the most value oriented changes first.
Roman, based on your advice i will definitely steer clear of the fiberglass and make changes, one at a time, in a single speaker with the use of an spl meter - thanks.
i was going to hold off on changing the inductor in the low pass filter based on DeanG's advice.
DeanG also provided me with this profile diagram of the speaker with proper foam placement. it is not entirely accurate as the ports protrude a significant distance into the cabinet. nevertheless, i think the point is that the foam shouldn't be over the ports.
DeanG also strongly recommended using kimber 12uF and 5uF caps as well as an 18uF Jantzen Crosscap. i am not planning on doing this mod but i have to say i would be interested in the result.
i think resistor replacement on the existing crossover boards is going to be pretty simple and since this may be the only components i change i don't think i'll make entirely new boards (to keep costs down).
i will definitely keep this thread active and i look forward to everyone's feedback.
your point about budget is a good one. i purchased these new for $1300 about 6 months ago (late graduation present to myself). i have grown unhappy with how they sound (in other words i've heard speakers since the purchase that i like more). my only option right now is upgrade, as replacement would be too costly. however, i am not sure they will sound the way i like regardless of money invested. i think at this point i am going to proceed with caution. try the most value oriented changes first.
Roman, based on your advice i will definitely steer clear of the fiberglass and make changes, one at a time, in a single speaker with the use of an spl meter - thanks.
i was going to hold off on changing the inductor in the low pass filter based on DeanG's advice.
DeanG also provided me with this profile diagram of the speaker with proper foam placement. it is not entirely accurate as the ports protrude a significant distance into the cabinet. nevertheless, i think the point is that the foam shouldn't be over the ports.
DeanG also strongly recommended using kimber 12uF and 5uF caps as well as an 18uF Jantzen Crosscap. i am not planning on doing this mod but i have to say i would be interested in the result.
i think resistor replacement on the existing crossover boards is going to be pretty simple and since this may be the only components i change i don't think i'll make entirely new boards (to keep costs down).
i will definitely keep this thread active and i look forward to everyone's feedback.
modification update
this weekend i completed the addition of sonic barrier ($100 incl. shipping) to the RF-7s as well as reducing the value of the 2 ohm resistor in the high pass filter by paralleling it with a 10 ohm resistor (in addition, all resistors were replaced by mills non-inductive resistors 1% of identical value).
here are some pics documenting the changes.
horn section
pre post
top driver pre post
bottom driver pre post
ports pre post
i cut the sonic barrier along the driver walls 1.5 inches short so that it would not affect airflow around the drivers. see pic
here is a photo of all the original damping material removed from one speaker. it was all reused in sections of the cabinet not directly adjacent to the woofers.
i obtained crude frequency response curves before and after all mods (radio shack spl meter and stereophile test CD). The SPL meter was located 1m from the speaker at a height which placed it between the driver and the horn.
none of the modifications seemed to alter the frequency profile. this is consistent with my inability to hear and substantive changes. there is a small possibility that clairity at low volumes may have improved and that bass may be slightly less controlled.
i still find these speaker a little overpowering and i think it may because of the significant peak at 6300 Hz. this peak begins around 2200 hz right at the crossover point.
this peak may not be speaker related as i switched out the speakers for a different pair (phase tech pc 3.1) which also had a peak at the same frequency.
i am hoping to get suggestions for the next best step. i guess i would need to determine the source of the 6300 Hz peak. my two options are source and room?
thanks and i hope my slow progress has not diminished interest in the project.
this weekend i completed the addition of sonic barrier ($100 incl. shipping) to the RF-7s as well as reducing the value of the 2 ohm resistor in the high pass filter by paralleling it with a 10 ohm resistor (in addition, all resistors were replaced by mills non-inductive resistors 1% of identical value).
here are some pics documenting the changes.
horn section
pre post
top driver pre post
bottom driver pre post
ports pre post
i cut the sonic barrier along the driver walls 1.5 inches short so that it would not affect airflow around the drivers. see pic
here is a photo of all the original damping material removed from one speaker. it was all reused in sections of the cabinet not directly adjacent to the woofers.
i obtained crude frequency response curves before and after all mods (radio shack spl meter and stereophile test CD). The SPL meter was located 1m from the speaker at a height which placed it between the driver and the horn.
none of the modifications seemed to alter the frequency profile. this is consistent with my inability to hear and substantive changes. there is a small possibility that clairity at low volumes may have improved and that bass may be slightly less controlled.
i still find these speaker a little overpowering and i think it may because of the significant peak at 6300 Hz. this peak begins around 2200 hz right at the crossover point.
this peak may not be speaker related as i switched out the speakers for a different pair (phase tech pc 3.1) which also had a peak at the same frequency.
i am hoping to get suggestions for the next best step. i guess i would need to determine the source of the 6300 Hz peak. my two options are source and room?
thanks and i hope my slow progress has not diminished interest in the project.
option 3 - 6.3khz peak
http://www.audioxpress.com/magsdirx/ax/addenda/media/koya2811.pdf
Hi,
note figure 2 in the above article - is your model the 6k peak one ?
TBH what you need need to measure is an average of in-room SPL
over a grid of typical listener positions, this is the most useful.
/sreten.
http://www.audioxpress.com/magsdirx/ax/addenda/media/koya2811.pdf
Hi,
note figure 2 in the above article - is your model the 6k peak one ?
TBH what you need need to measure is an average of in-room SPL
over a grid of typical listener positions, this is the most useful.
/sreten.
huge help
sreten - that article is a huge help. my spl meter is definitely the problem. i was leaning in that direction because i had swapped out speakers, cd player, dac, amp, and changed the orientation of the speakers in the room. i say leaning because i could not accept the idea that someone would manufacture a device that could be out by 15dB. clearly i was wrong.
at this point the only mod left on the table is to swap the capacitors. i may still try this but i don't know where it falls in the audio project priority list.
part of the reason i may still do this mod is that a DIYer who works a my local audio store suggested that klipsch designs/models their speakers with idealized components. thus any component which moves closer to the ideal should hopefully come closer to the original design goals. whether or not this is significant is another issue. i am going to do some more looking around.
immediately i think i might invest my time in learning speaker workshop so that i could at least properly quantify any subsequent changes.
thanks
sreten - that article is a huge help. my spl meter is definitely the problem. i was leaning in that direction because i had swapped out speakers, cd player, dac, amp, and changed the orientation of the speakers in the room. i say leaning because i could not accept the idea that someone would manufacture a device that could be out by 15dB. clearly i was wrong.
at this point the only mod left on the table is to swap the capacitors. i may still try this but i don't know where it falls in the audio project priority list.
part of the reason i may still do this mod is that a DIYer who works a my local audio store suggested that klipsch designs/models their speakers with idealized components. thus any component which moves closer to the ideal should hopefully come closer to the original design goals. whether or not this is significant is another issue. i am going to do some more looking around.
immediately i think i might invest my time in learning speaker workshop so that i could at least properly quantify any subsequent changes.
thanks
Hi p.dow
this project has been on hold until i get my loudspeaker measurement tools developed - I would not advise doing much work on the speakers without them because most changes are difficult to reverse. Nevertheless, there are two thing you can try to get rid of the sibilance you and many others have described. One or both may work.
The first is already described in this thread - increasing the "notch" in the notch filter by reducing the resistance of the resistor in the horn crossover. this definitely works.
The second involves placing a acoustic foam plug in the horn. This is done to reduce higher order modes (HOM). Gedlee describes this in one of his threads - i can't recall which right now. Don't rely on the horn angles provided by klipsh to cut your foam - make a template. This goes for just about all info from klipsch - it is often wrong.
Another modifications that i think might help is adding more damping material inside the cabinet. I would put quite a bit at the top and bottom of the cabinet (without blocking the ports) to prevent a standing wave along that axis as the frequency of the wave falls within a critical listening region (or so i have read). Also, make sure the foam that is already present is not blocking the ports.
The above mentioned modification are all cheap. More expensive mods like crossover cap upgrades would likely cost a lot more, may not result in improvement, and i wouldn't try without measurement tools.
I should say that if you don't really like the sound of these speakers, my feeling is that you won't be able to significantly alter it, and you might be better off just getting a different speaker.
My big complaint about these speakers is the lack of bass. Since you did not mention the problem i am curious about what amps you are using to drive the speakers.
this project has been on hold until i get my loudspeaker measurement tools developed - I would not advise doing much work on the speakers without them because most changes are difficult to reverse. Nevertheless, there are two thing you can try to get rid of the sibilance you and many others have described. One or both may work.
The first is already described in this thread - increasing the "notch" in the notch filter by reducing the resistance of the resistor in the horn crossover. this definitely works.
The second involves placing a acoustic foam plug in the horn. This is done to reduce higher order modes (HOM). Gedlee describes this in one of his threads - i can't recall which right now. Don't rely on the horn angles provided by klipsh to cut your foam - make a template. This goes for just about all info from klipsch - it is often wrong.
Another modifications that i think might help is adding more damping material inside the cabinet. I would put quite a bit at the top and bottom of the cabinet (without blocking the ports) to prevent a standing wave along that axis as the frequency of the wave falls within a critical listening region (or so i have read). Also, make sure the foam that is already present is not blocking the ports.
The above mentioned modification are all cheap. More expensive mods like crossover cap upgrades would likely cost a lot more, may not result in improvement, and i wouldn't try without measurement tools.
I should say that if you don't really like the sound of these speakers, my feeling is that you won't be able to significantly alter it, and you might be better off just getting a different speaker.
My big complaint about these speakers is the lack of bass. Since you did not mention the problem i am curious about what amps you are using to drive the speakers.
rf-7
thanks for the reply .
mcintosh 275V 75 w/c
and sometimes sansui G7700 120 wc
they both rock the rf-7's
plenty of bass
just not enough mid sometimes
and the schrillness comeing out occasionally with certain passages in the music.... just enough so its noticable.
i have a set of acoustic zen adagios (2 K$ range) speakers and the rf-7's are more to my likeing but the adagios are good to go to sometimes.
i am getting dean to do my xovers so i have set myself on that path.
thanks for the reply .
mcintosh 275V 75 w/c
and sometimes sansui G7700 120 wc
they both rock the rf-7's
plenty of bass
just not enough mid sometimes
and the schrillness comeing out occasionally with certain passages in the music.... just enough so its noticable.
i have a set of acoustic zen adagios (2 K$ range) speakers and the rf-7's are more to my likeing but the adagios are good to go to sometimes.
i am getting dean to do my xovers so i have set myself on that path.
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