As the cones are flared , the fairly simple mod you could have tried to reduce the 1k3 - 1k7 problem in the frequency response will be much more difficult to do , and too risky for in-experienced to try , and I'd probably not do it myself except to experiment on unwanted drivers . Less risky with staight sided cones .
I was losing concentration previously and meant to ask if the Polyfill you have is in sheet form , as cut from a roll or similar , and thus if you have flat pieces at least 7.25" less the thickness of the current in-cabinet foam lining in dimensions , OR , if it is small piece polyfill , such as in lump form ?
Pieces which can be cut to size and optimally placed will give better audible results than small loose pieces being blown about by the air-pump action of the moving driver .
Any doubters reading this can experiment and listen to the difference after I posted about the positioning .
The web-site described GW project''s user is listening primarily in the Ambient Field as he has the drivers pointing close to vertical and seems to be listening at a distance - perhaps 10ft or more away - thus is not hearing as much annoying effect of the upper mid resonant spike , and the 1k7 area valley is partially confused by other acoustic effects in the room . That design and similar , such as some of the "Bose" loudspeaker designs , can be quite satisfactory for listening to music {depending on one's expectations and taste} , but is of little use for critical evaluation of recordings in monitoring situations , etc ... , which I think you may wish to do some of as you have a Mackie mixer .
I was losing concentration previously and meant to ask if the Polyfill you have is in sheet form , as cut from a roll or similar , and thus if you have flat pieces at least 7.25" less the thickness of the current in-cabinet foam lining in dimensions , OR , if it is small piece polyfill , such as in lump form ?
Pieces which can be cut to size and optimally placed will give better audible results than small loose pieces being blown about by the air-pump action of the moving driver .
Any doubters reading this can experiment and listen to the difference after I posted about the positioning .
The web-site described GW project''s user is listening primarily in the Ambient Field as he has the drivers pointing close to vertical and seems to be listening at a distance - perhaps 10ft or more away - thus is not hearing as much annoying effect of the upper mid resonant spike , and the 1k7 area valley is partially confused by other acoustic effects in the room . That design and similar , such as some of the "Bose" loudspeaker designs , can be quite satisfactory for listening to music {depending on one's expectations and taste} , but is of little use for critical evaluation of recordings in monitoring situations , etc ... , which I think you may wish to do some of as you have a Mackie mixer .
a Mechanical Filter .
Basically the problems in the Goldwood's cone are of mechanical origin , and mechanical filters will reduce them more easily than electrical filters , {and I cannot design electrical filters for a driver I do not have to measure} .
Remember , this driver , despite the sellers on-site brief description , is basically a small bass and low mids driver , probably intended for cross-over somewhere from 400 to 600 Hz .
The 1k7 valley is owing to phase cancellation , probably as result of one or more of the concentric circle enclosed areas of the cone moving in almost the opposite polarity to one or more of the other similar areas . Such behavior is common in concentric ridged cones . The concentric ridges stiffen the cone against radial breakup , and sufficiently for use as a bass driver , but can cause circular breakup activity in cones to be worse than would otherwise be . This will be difficult to apply a mechanical solution to , thus I won't describe here .
Time has run out now , so I'll post the mechanical filter idea for the upper mid spike in next post .
Look for availability of a Urethane Bond type adhesive which will be needed to do this , unless I can find something else that will work .
Basically the problems in the Goldwood's cone are of mechanical origin , and mechanical filters will reduce them more easily than electrical filters , {and I cannot design electrical filters for a driver I do not have to measure} .
Remember , this driver , despite the sellers on-site brief description , is basically a small bass and low mids driver , probably intended for cross-over somewhere from 400 to 600 Hz .
The 1k7 valley is owing to phase cancellation , probably as result of one or more of the concentric circle enclosed areas of the cone moving in almost the opposite polarity to one or more of the other similar areas . Such behavior is common in concentric ridged cones . The concentric ridges stiffen the cone against radial breakup , and sufficiently for use as a bass driver , but can cause circular breakup activity in cones to be worse than would otherwise be . This will be difficult to apply a mechanical solution to , thus I won't describe here .
Time has run out now , so I'll post the mechanical filter idea for the upper mid spike in next post .
Look for availability of a Urethane Bond type adhesive which will be needed to do this , unless I can find something else that will work .
The poly-fill I have(if I can find it) is the loose fluffy sort you make pillows and such with.
I'm growing to like these speakers more & more as I listen to them as the crossover and pad parts semm to have made a large difference in the tone. The bad attributes of the woofer seem to be more evident if played loud and only then if you're sitting close in front of them. They sound quite good loud from a distance of ten feet or more. My wife even seems to like the rig now(she owns a Carver system with Bose 901s).
Someday I will build some better speakers with a pair of the Dayton cabinets but for now these will have to do barring a big insurance settlement.
Thanks for your help and patience Alan.
RDV
I'm growing to like these speakers more & more as I listen to them as the crossover and pad parts semm to have made a large difference in the tone. The bad attributes of the woofer seem to be more evident if played loud and only then if you're sitting close in front of them. They sound quite good loud from a distance of ten feet or more. My wife even seems to like the rig now(she owns a Carver system with Bose 901s).
Someday I will build some better speakers with a pair of the Dayton cabinets but for now these will have to do barring a big insurance settlement.
Thanks for your help and patience Alan.
RDV
Carver and Bose 901 - I'll guess that your wife has had these for 15-20 years or longer , or was given them by some-one who bought them back then !
If you chance upon 2 of those small Bose cone drivers , as used in the 901 , they would likely make suitable midrange drivers to use with the Gildwoods and Pioneer tweeters , but I do not have any specs on the Bose drivers .
The polyfill you have may be in some shape different to either that I've seen , or perhaps a different type of substance as "poly" is a part of the name of several types of plastics .
Anyway , polyfills are not particually good for sound absorbtion , unless specifically formulated for such , so if you can't find yours , don't worry nor buy any .
Look around any building and demolition sites in your area for some discarded Fibreglass batts , or remains of a roll of fibreglass insulation {it will likely be either yellow or pink in colour} . Any paper or foil backing can be torn off after you get it home . Hardware shops sell it in large packs , and those I have seen are much too large for the quantity you will need { only sufficient to fill the 2 cabinets} , but a shop may have an open pack or a left-over piece from a roll , so its worth asking .
It is available in 1" ; 2" ; 3" ; 4" ; thicknesses, and any will do , though the 3" I've seen and used is a convenient size as the 1" is too floppy , and the 4" is not as consistent in its internal density in some samples .
"R19" is the standard Thermal classification to ask for , for a type often used in speaker cabinets . This is a heat rating and not an acoustic rating , and there are some acoustic fibreglass products that are lower number than 19 , but acoustically good to use , eg:- "Owens Corning" have four grades {in density} :- types 701 ; 711 ; 703 ; 705 , and in all the thicknesses above .
But , if you have to buy it and are asking an acoustic opinion , the Owen Corning stuff is made for sound proofing {as well as heat } , and sound proofing is Acoustic Isolation , which is a slightly different application to what we do with fibreglass inside speaker cabinets , thus do not buy rigid fibreglass that is very densely packed , as that can decrease the cabinet volume {obviously} . Look at an open cut edge and ensure it looks sufficiently soft and porous for air to enter and vibrate the fibres .
The flat sides of the batts are often semi-sealed , but if they are placed with cut edges facing the back of the driver , they work well - at least the 3" thick ones I have used .
If no Urethane Bond type adhesives sold in small quantity in the shops in your area , then ask if any Butyl Latex - in small quantity , but if you buy some , do not open it {nor any Urethane Bond} until you actually start the mod , which I'll describe when you have found one of such .
Once exposed to air Butyl Latex cures and any remaining may become unuseable fairly quickly . With Urethane Bond , if in a squeeze tube , the lid on immediately keeps it useable for longer .
Felt - either made from cotton or wool {wool felt only if treated against insects laying eggs in or eating} - and not felt made from any synthetic materials .
1mm thick {slightly less than 1/16"} will do the job to some degree , and 1/16" will do it more so . It will be used to cover the centre domes of the woofer cones , thus you do need only a little , but get twice the quantity or a little more again , as you will likely have to make a couple as trials till you get the notches I'll describe the right width .
If you cannot find any suitable felt , then cotton Flannel cloth will work to some degree , but most I have seen is very thin , eg:- the type shirts and winter pyjamas are made from is less than 1mm thick {often called "Flannelette"}. You may find thicker at a shop that sells cloth for women to make clothes from - ask your wife !
Must be cotton , and not "acrylic" nor any blend of cotton/acrylic nor synthetics blend .
Think about the colour you buy as you will have to look at it , and your wife also , and dying it may affect its softness or its ability to be stuck suitably securely .
Post what you can find or buy of the above , and I'll post the how to .
If you chance upon 2 of those small Bose cone drivers , as used in the 901 , they would likely make suitable midrange drivers to use with the Gildwoods and Pioneer tweeters , but I do not have any specs on the Bose drivers .
The polyfill you have may be in some shape different to either that I've seen , or perhaps a different type of substance as "poly" is a part of the name of several types of plastics .
Anyway , polyfills are not particually good for sound absorbtion , unless specifically formulated for such , so if you can't find yours , don't worry nor buy any .
Look around any building and demolition sites in your area for some discarded Fibreglass batts , or remains of a roll of fibreglass insulation {it will likely be either yellow or pink in colour} . Any paper or foil backing can be torn off after you get it home . Hardware shops sell it in large packs , and those I have seen are much too large for the quantity you will need { only sufficient to fill the 2 cabinets} , but a shop may have an open pack or a left-over piece from a roll , so its worth asking .
It is available in 1" ; 2" ; 3" ; 4" ; thicknesses, and any will do , though the 3" I've seen and used is a convenient size as the 1" is too floppy , and the 4" is not as consistent in its internal density in some samples .
"R19" is the standard Thermal classification to ask for , for a type often used in speaker cabinets . This is a heat rating and not an acoustic rating , and there are some acoustic fibreglass products that are lower number than 19 , but acoustically good to use , eg:- "Owens Corning" have four grades {in density} :- types 701 ; 711 ; 703 ; 705 , and in all the thicknesses above .
But , if you have to buy it and are asking an acoustic opinion , the Owen Corning stuff is made for sound proofing {as well as heat } , and sound proofing is Acoustic Isolation , which is a slightly different application to what we do with fibreglass inside speaker cabinets , thus do not buy rigid fibreglass that is very densely packed , as that can decrease the cabinet volume {obviously} . Look at an open cut edge and ensure it looks sufficiently soft and porous for air to enter and vibrate the fibres .
The flat sides of the batts are often semi-sealed , but if they are placed with cut edges facing the back of the driver , they work well - at least the 3" thick ones I have used .
If no Urethane Bond type adhesives sold in small quantity in the shops in your area , then ask if any Butyl Latex - in small quantity , but if you buy some , do not open it {nor any Urethane Bond} until you actually start the mod , which I'll describe when you have found one of such .
Once exposed to air Butyl Latex cures and any remaining may become unuseable fairly quickly . With Urethane Bond , if in a squeeze tube , the lid on immediately keeps it useable for longer .
Felt - either made from cotton or wool {wool felt only if treated against insects laying eggs in or eating} - and not felt made from any synthetic materials .
1mm thick {slightly less than 1/16"} will do the job to some degree , and 1/16" will do it more so . It will be used to cover the centre domes of the woofer cones , thus you do need only a little , but get twice the quantity or a little more again , as you will likely have to make a couple as trials till you get the notches I'll describe the right width .
If you cannot find any suitable felt , then cotton Flannel cloth will work to some degree , but most I have seen is very thin , eg:- the type shirts and winter pyjamas are made from is less than 1mm thick {often called "Flannelette"}. You may find thicker at a shop that sells cloth for women to make clothes from - ask your wife !
Must be cotton , and not "acrylic" nor any blend of cotton/acrylic nor synthetics blend .
Think about the colour you buy as you will have to look at it , and your wife also , and dying it may affect its softness or its ability to be stuck suitably securely .
Post what you can find or buy of the above , and I'll post the how to .
additions to the above post .
Fibreglass :-
- if you find a soft sheet , don't roll it up tightly or compress it , just roll it loosely to carry home . Similarly , don't compress a batt or put anything heavy on top of it . Some of these will not resume their open structure after compression , and it has to remain expanded to absorb - this is where this application is different to a sound barrier for sound proofing .
The R rating depends on the thickness of the batt . The standard R19 fibreglass batt sold in the USA seems to be the 3" thickness . This is for ordinary fibreglass insulation batts , {the Owens Corning batts are particular developed products} .
Felt :-
I meant the soft type , like a thick cloth , and not Hat Felt as that is too stiff for this application .
Saddle Felt may be soft enough , but I do not know what thicknesses it is made in , so if a Saddle-maker or Riders' Supply store in your area enquire there .
"butyl" is a synthetic rubber - a long life type . The adhesives will have a rubber or latex ingredient listed .
For Felts ; Urethane Bond adhesive ; Butyl Latex or Butyl Latex adhesives , ask also at Crafts' stores - Hobbycrafts' types , and at Handicrafts' stores for Felts and Flannel Cloth .
Try also at Artists' Supply stores - particually any near an Arts' College or a University .
Flannel cloth has to be a type that is flat on at least one side -{some are made with raised ridges on surface}- and of even density through-out .
Fibreglass :-
- if you find a soft sheet , don't roll it up tightly or compress it , just roll it loosely to carry home . Similarly , don't compress a batt or put anything heavy on top of it . Some of these will not resume their open structure after compression , and it has to remain expanded to absorb - this is where this application is different to a sound barrier for sound proofing .
The R rating depends on the thickness of the batt . The standard R19 fibreglass batt sold in the USA seems to be the 3" thickness . This is for ordinary fibreglass insulation batts , {the Owens Corning batts are particular developed products} .
Felt :-
I meant the soft type , like a thick cloth , and not Hat Felt as that is too stiff for this application .
Saddle Felt may be soft enough , but I do not know what thicknesses it is made in , so if a Saddle-maker or Riders' Supply store in your area enquire there .
"butyl" is a synthetic rubber - a long life type . The adhesives will have a rubber or latex ingredient listed .
For Felts ; Urethane Bond adhesive ; Butyl Latex or Butyl Latex adhesives , ask also at Crafts' stores - Hobbycrafts' types , and at Handicrafts' stores for Felts and Flannel Cloth .
Try also at Artists' Supply stores - particually any near an Arts' College or a University .
Flannel cloth has to be a type that is flat on at least one side -{some are made with raised ridges on surface}- and of even density through-out .
your cabinets :-
Do your cabinets have a removeable back or front , or will anything put in have to be fitted through the woofer cut-out ?
Whilst you are looking in stores you might find a 3.3cm {1 5/16"} diameter cork or rubber stopper that can be tightly stuck into those too small ports . Look for in a rubber plug for a basin also . Yes that is flexible , but with all the filler in the cabinet a very small degree of flexibility will not be a problem .
As now in your cabinets the Goldwoods will have an in-box resonance at approximately 90Hz or a little higher , and with a Q of greater than 1 , thus a somewhat emphasized bass , almost boomy around a few notes .
Play your guitars directly through your Mackie mixer into the speakers . The low Fsharp and G notes on the bass string will likely be more prominent than the open E bass note as result of this resonance . As many guitars I have played have a somewhat more prominant G {3rd fret bass note} than the open bass E , this additional speaker emphasis may be annoying .
When the cabinet is optimally stuffed the Q of the resonance will be lowered enough to reduce that effect , and hopefully the in-box resonance itself will have been lowered sufficiently in frequency to be closer to the pitch of the open E note .
This cabinet is too small , even when stuffed with a suitable fibreglass , to get the Goldwood's in-box resonance down to bass guitar frequencies .
With the SEAS RLY in that box stuffed you will get some of the fundamentals of bass guitar low notes , plus a psychoacoustic effect as the brain interprets some types of harmonic distortion when the normal upper harmonics of an instrument are present and tricks the hearing as if hearing the actual fundamental pitch of a lower note than the speaker can reproduce . Thus if the SEAS in-box resonance can be got down to the lowest pitched B note of the bass guitar -{eg :- at 7th fret on E string and 2nd fret on A string}- , the brain will hear the open bass guitar E , when played , almost as if the speaker would sound if it could reproduce the low E fundamental .
Low bass guitar E fundamental is a little above 40Hz .
The B fundamental is about 60Hz , and this pitch is a harmonic of the 40Hz E - {you will have heard this an octave higher on your guitar - E open is a little above 80Hz , and the B 7th fret is about 120Hz} .
This can be got to work in a sealed cabinet , and I think will with the SEAS RLY in your cabinets if optimally stuffed , and of course better later in a larger cabinet .
Do your cabinets have a removeable back or front , or will anything put in have to be fitted through the woofer cut-out ?
Whilst you are looking in stores you might find a 3.3cm {1 5/16"} diameter cork or rubber stopper that can be tightly stuck into those too small ports . Look for in a rubber plug for a basin also . Yes that is flexible , but with all the filler in the cabinet a very small degree of flexibility will not be a problem .
As now in your cabinets the Goldwoods will have an in-box resonance at approximately 90Hz or a little higher , and with a Q of greater than 1 , thus a somewhat emphasized bass , almost boomy around a few notes .
Play your guitars directly through your Mackie mixer into the speakers . The low Fsharp and G notes on the bass string will likely be more prominent than the open E bass note as result of this resonance . As many guitars I have played have a somewhat more prominant G {3rd fret bass note} than the open bass E , this additional speaker emphasis may be annoying .
When the cabinet is optimally stuffed the Q of the resonance will be lowered enough to reduce that effect , and hopefully the in-box resonance itself will have been lowered sufficiently in frequency to be closer to the pitch of the open E note .
This cabinet is too small , even when stuffed with a suitable fibreglass , to get the Goldwood's in-box resonance down to bass guitar frequencies .
With the SEAS RLY in that box stuffed you will get some of the fundamentals of bass guitar low notes , plus a psychoacoustic effect as the brain interprets some types of harmonic distortion when the normal upper harmonics of an instrument are present and tricks the hearing as if hearing the actual fundamental pitch of a lower note than the speaker can reproduce . Thus if the SEAS in-box resonance can be got down to the lowest pitched B note of the bass guitar -{eg :- at 7th fret on E string and 2nd fret on A string}- , the brain will hear the open bass guitar E , when played , almost as if the speaker would sound if it could reproduce the low E fundamental .
Low bass guitar E fundamental is a little above 40Hz .
The B fundamental is about 60Hz , and this pitch is a harmonic of the 40Hz E - {you will have heard this an octave higher on your guitar - E open is a little above 80Hz , and the B 7th fret is about 120Hz} .
This can be got to work in a sealed cabinet , and I think will with the SEAS RLY in your cabinets if optimally stuffed , and of course better later in a larger cabinet .
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