hi
hi
peterpan
totally soundreinforcement oriented
i know the design of the 802 matrix its a very good design and will work with any size of speakers to produce extreme realism in mids and midbass - the boxes are inricate to make , normally ive had to make thermocol models to explain such designs to carpenters
anyway
we will draw it in parts and explain the entire cabinet to you when you visit us , the dimensions may change as we have 1 ohms speakers but not of 4 1/2 inch size though i have the bose replacement cone / coil / spider kit
all the spks are wired in series in the 802
the panarray tops model is similar a matrix , all the mid woofers fire into their own enclosure / it will be diffcult to put in words we will draw that for you too
as for the 6 inches , we know the concept but not the enclosure design
what i have to say is most important now
the bose enclosures or other enclosures like the jbl control series (and all such) enclosures
are made of a accoustic poly_something (forgetting the technical name)
the important feature of these cabinets are that they resonate when the speaker is playing in the audible range and depending on application produce extremely impressive midbass frequencies
in the sence that the entire enclosure gets excited and vibrates such vibrations add to the spl
therefore
if you pull out the bose drivers place them in exact replica boxes of plywood / or other material , than that used by bose
the speaker will not play exactly like the 802 s , though youve used bose drivers
yet the box design (the matrix concept) and its application can have very good results even when ply wood is used (again strictly in sound reinforcement)
suranjan
hi
peterpan
totally soundreinforcement oriented
i know the design of the 802 matrix its a very good design and will work with any size of speakers to produce extreme realism in mids and midbass - the boxes are inricate to make , normally ive had to make thermocol models to explain such designs to carpenters
anyway
we will draw it in parts and explain the entire cabinet to you when you visit us , the dimensions may change as we have 1 ohms speakers but not of 4 1/2 inch size though i have the bose replacement cone / coil / spider kit
all the spks are wired in series in the 802
the panarray tops model is similar a matrix , all the mid woofers fire into their own enclosure / it will be diffcult to put in words we will draw that for you too
as for the 6 inches , we know the concept but not the enclosure design
what i have to say is most important now
the bose enclosures or other enclosures like the jbl control series (and all such) enclosures
are made of a accoustic poly_something (forgetting the technical name)
the important feature of these cabinets are that they resonate when the speaker is playing in the audible range and depending on application produce extremely impressive midbass frequencies
in the sence that the entire enclosure gets excited and vibrates such vibrations add to the spl
therefore
if you pull out the bose drivers place them in exact replica boxes of plywood / or other material , than that used by bose
the speaker will not play exactly like the 802 s , though youve used bose drivers
yet the box design (the matrix concept) and its application can have very good results even when ply wood is used (again strictly in sound reinforcement)
suranjan
[B]assessing criterias that govern power handling of a driver[/B]
HOW THE POWER OUTPUT IS RATED FOR A DRIVER
AND THE CRITERIAS THAT NEEDS TO BE CHECKED BY USERS TO DETERMINE THE RATING
PLUS
WHAT ALL PARAMETERS DOES A RATING DEPEND ON
hi
this statement can be said as correct that :
a power rating given to a driver , means that at all input levels of the driver rating within its specified limit , the driver :
1 ) should perform within the rating in long term use , robustness
2) should perform within very acceptable limits of distortion
3) and should show a certain limit of linearity in relation with the , actual accoustic power output increase to the input power supplied from the amps
without compression
the distortion is now adays mostly the deciding factor of the power rating including long term use
Here it needs to be devided in two sections
FIRST SECTION
in a broad context
distortion / you will find some speakers distorting _ much before the voice coil actually burns out
for eg - considering a driver in which this takes place :
a driver or if they are pro audio or drivers with simple pole vent cooling with the coils set in a tight magnetic gap - the coil can be on a paper former , oridinary wires used in the vc s
the vc s temperature will not rise easily normally 60 deg max , at this time it will distort
then this distortion is not from the vc temperature
(though in most books vc temp is one of the main source of distortion , why ? read on ....)
there are 3 basic types of non linearity in a transducer , these generate distortion , due to this distortion the voice coil heats up / at this moment no amount of cooling can help ,
the distortion effect from driver non linearities are such that it may lead to vc temp rise exponentially leading to vc burn out
the non linearities are
1. non linearity in the suspension mechanism
2. non linearity in the motor sturucture
3. non linearity caused when a coil moves in a permanent magnet motor structure (this is bound to happen even if the above 2 non linearities are addressed well )
to check for these non linearities while purchasing drivers
1. suspension non linearity
for the x - max of the driver you would like to purchase (or the one specified by the manufacturer) meaning you either know the x-max or have one in mind , then :
step a
push the driver cone downwards by that amount , it should go down linearly (the stiffness of the suspension increasing linearly) to the amount of the x-max
step b
pull the cone upwards towards you from beneath and it should come up to the specified x-max , again stiffness increasing linearly
if this does not take place the driver will distort -
unless the transducer manufacturer identifies specifically that such a non - linearity has been addressed , by making suitable compensations in the vc itself
2. motorstructure non linearity
fringe fields exists at the magnetic gap - the motor structure should be - sfg a symmetrical field geometry _ topology
therefore while purchasing a driver look if the motorstructure is - sfg or not
since expenses goes up in a sfg structure it will be specifically mentioned mentioned by the driver manufacturer , to inform customers
3. Non linearity caused when a coil moves in a permanent magnet motor structure
explaining this nature of non linearity is complex , anyone interested can see the sections on shorting rings in my thread
what is important
is that : -
has this been addressed by the transducer manufacturer
it is addressed by shorting rings placed in the motorstructure
since this too involves expence , and a considerable slow down in the manufacturing process this too will be specified by the driver manufacturer , to inform customers
-
the above are the main sources of distortion that determines the safe operating power of a driver , and are not the only sources of driver distortion (other sources of distortion are eddys , bottoming to name a few)
due to such complex stuff good driver manufacturers all over the world can be counted on finger tips
------------------------------------------------------------------------------------
SECOND SECTION
in good drivers context
good drivers are in which all the above criterias have been addressed
then the rise in vc temperature over long time use / the cooling efficiency comes in , and mostly all speaker failures of reputated manufacturers result from vc burn out (as mentioned by Navin)
mostly these limits are tested thoroughly and drivers tested to distruction and safe regions specified
i have found driver malfunction due to negligence of owners to go in for a service contract when pro audio drivers are used eg - movie halls , discs
in home audio , sources of reputated driver burn outs are :
a)
amp malfunction and dc component generation in the drive signal or signal clipping
speacially when high power speakers are used by under powered amps , many people do not even consider that a 35 w amp can damage a 100 w speaker system _ plain simple signal clipping can distroy well made drivers
if you have an under powered amp please ask a sound engineer to determine the clipping levels of your amp and restrict from running at clipping levels (in high end audio amps from manufacturers like Nad and onwards this is built in as standard , in the circuitry , therefore the prices)
b)
or the suspension parts have outlived _ may be the owner !
thanks Amp Man , hope this comes of use ,
Suranjan Das Gupta
Transducer design engineer
HOW THE POWER OUTPUT IS RATED FOR A DRIVER
AND THE CRITERIAS THAT NEEDS TO BE CHECKED BY USERS TO DETERMINE THE RATING
PLUS
WHAT ALL PARAMETERS DOES A RATING DEPEND ON
hi
this statement can be said as correct that :
a power rating given to a driver , means that at all input levels of the driver rating within its specified limit , the driver :
1 ) should perform within the rating in long term use , robustness
2) should perform within very acceptable limits of distortion
3) and should show a certain limit of linearity in relation with the , actual accoustic power output increase to the input power supplied from the amps
without compression
the distortion is now adays mostly the deciding factor of the power rating including long term use
Here it needs to be devided in two sections
FIRST SECTION
in a broad context
distortion / you will find some speakers distorting _ much before the voice coil actually burns out
for eg - considering a driver in which this takes place :
a driver or if they are pro audio or drivers with simple pole vent cooling with the coils set in a tight magnetic gap - the coil can be on a paper former , oridinary wires used in the vc s
the vc s temperature will not rise easily normally 60 deg max , at this time it will distort
then this distortion is not from the vc temperature
(though in most books vc temp is one of the main source of distortion , why ? read on ....)
there are 3 basic types of non linearity in a transducer , these generate distortion , due to this distortion the voice coil heats up / at this moment no amount of cooling can help ,
the distortion effect from driver non linearities are such that it may lead to vc temp rise exponentially leading to vc burn out
the non linearities are
1. non linearity in the suspension mechanism
2. non linearity in the motor sturucture
3. non linearity caused when a coil moves in a permanent magnet motor structure (this is bound to happen even if the above 2 non linearities are addressed well )
to check for these non linearities while purchasing drivers
1. suspension non linearity
for the x - max of the driver you would like to purchase (or the one specified by the manufacturer) meaning you either know the x-max or have one in mind , then :
step a
push the driver cone downwards by that amount , it should go down linearly (the stiffness of the suspension increasing linearly) to the amount of the x-max
step b
pull the cone upwards towards you from beneath and it should come up to the specified x-max , again stiffness increasing linearly
if this does not take place the driver will distort -
unless the transducer manufacturer identifies specifically that such a non - linearity has been addressed , by making suitable compensations in the vc itself
2. motorstructure non linearity
fringe fields exists at the magnetic gap - the motor structure should be - sfg a symmetrical field geometry _ topology
therefore while purchasing a driver look if the motorstructure is - sfg or not
since expenses goes up in a sfg structure it will be specifically mentioned mentioned by the driver manufacturer , to inform customers
3. Non linearity caused when a coil moves in a permanent magnet motor structure
explaining this nature of non linearity is complex , anyone interested can see the sections on shorting rings in my thread
what is important
is that : -
has this been addressed by the transducer manufacturer
it is addressed by shorting rings placed in the motorstructure
since this too involves expence , and a considerable slow down in the manufacturing process this too will be specified by the driver manufacturer , to inform customers
-
the above are the main sources of distortion that determines the safe operating power of a driver , and are not the only sources of driver distortion (other sources of distortion are eddys , bottoming to name a few)
due to such complex stuff good driver manufacturers all over the world can be counted on finger tips
------------------------------------------------------------------------------------
SECOND SECTION
in good drivers context
good drivers are in which all the above criterias have been addressed
then the rise in vc temperature over long time use / the cooling efficiency comes in , and mostly all speaker failures of reputated manufacturers result from vc burn out (as mentioned by Navin)
mostly these limits are tested thoroughly and drivers tested to distruction and safe regions specified
i have found driver malfunction due to negligence of owners to go in for a service contract when pro audio drivers are used eg - movie halls , discs
in home audio , sources of reputated driver burn outs are :
a)
amp malfunction and dc component generation in the drive signal or signal clipping
speacially when high power speakers are used by under powered amps , many people do not even consider that a 35 w amp can damage a 100 w speaker system _ plain simple signal clipping can distroy well made drivers
if you have an under powered amp please ask a sound engineer to determine the clipping levels of your amp and restrict from running at clipping levels (in high end audio amps from manufacturers like Nad and onwards this is built in as standard , in the circuitry , therefore the prices)
b)
or the suspension parts have outlived _ may be the owner !
thanks Amp Man , hope this comes of use ,
Suranjan Das Gupta
Transducer design engineer
The elusive guru strikes again and ver helpful
Hey Suranjan,,
Wow!! that was some long lecture(whew)... but extremely helpful. You certainly know your fingers from your toes. I am very very impressed. In fact I am expecting you to solve my Bose box dimensions problems because this is the design that I REALLY WANT TO HOMEBREW!!. As you already know I am in live sound so I need this!!. I haven't yet read much of your posting but I have copied & pasted it as a doc file and hope to read the details again later in the day.
I hope I'm not too hasty in saying this, but I have a feeling you're the best thing thats happenned to this forum (although elusive). If you'd ask me I'd suggest you stick to the lab and leave the driver making business to someone else like your friend Vicky. Thats not to say you're any less competent - business wise, just a little bit confused and like someone said earlier - disorganised.
None the less, I am happy with your swift response. Now if you will be kind enough, would you mind answering my wild 'welding transformer' question in the "Toroidal Transformers in B/lore" thread.
My Regards and peace to everyone here.
Patrick
Hey Suranjan,,
Wow!! that was some long lecture(whew)... but extremely helpful. You certainly know your fingers from your toes. I am very very impressed. In fact I am expecting you to solve my Bose box dimensions problems because this is the design that I REALLY WANT TO HOMEBREW!!. As you already know I am in live sound so I need this!!. I haven't yet read much of your posting but I have copied & pasted it as a doc file and hope to read the details again later in the day.
I hope I'm not too hasty in saying this, but I have a feeling you're the best thing thats happenned to this forum (although elusive). If you'd ask me I'd suggest you stick to the lab and leave the driver making business to someone else like your friend Vicky. Thats not to say you're any less competent - business wise, just a little bit confused and like someone said earlier - disorganised.
None the less, I am happy with your swift response. Now if you will be kind enough, would you mind answering my wild 'welding transformer' question in the "Toroidal Transformers in B/lore" thread.
My Regards and peace to everyone here.
Patrick
About the Bose cab material
Suranjan,
The material for the speakers is mica reinforced polyethylene. Is it available in India, S.E.Asia? What difference acoustically would it make if I were to use MDF?
Patrick
Suranjan,
The material for the speakers is mica reinforced polyethylene. Is it available in India, S.E.Asia? What difference acoustically would it make if I were to use MDF?
Patrick
Goldy, Ashok, Vivek...!
Sorry for asking this again.
I searched in SJP road...went to this shop u had mentioned...(their hording read that they deal in BPL...is thei sthe same guy...)
I asked him for BPL speakers and he said he dont have any...
however he had the stuff u generally use in tv...those small sheilded ones. Can some one guide me please...
PS: i am a bit blind...-3.0D on both eyes...!! 🙂
Chances are that i might have missed some shop.. The globe electronics was closed both times i went there...!
ajju.
Ajju, the shop is right opposite the Om Electronics store. Maybe you can ask some of the other shops there. If you are facing the Bangalore Electronics Enterprises shop, you will see woofers and tweeters kept in a tall glass case. Those are the BPL speakers.
Re: hi
what you might be able to getaway with is thinner crossection of ply and than control the cabinet speak by using bracing and damping. what i am saying is that make the cabient live to begin with then use bracing to control the freq.you want the cabinet to be live and damping to control the level of the liveliness of teh cabinet.
even then dont expect to replicate the effect of mica filled poly. if you arei into moulding etc.. you might be able to build a box out of fiberglass matting (bonded with epoxy).
mica filled poly (braced) has a resonace that is soft and using bracing i suspect bose / jbl use the cabinet to assist the midbass (100-300hz) response of the speaker. I have exprimented with this concpet (not successfully enough) as a compensation for baffle step.
hunter audio said:
what you might be able to getaway with is thinner crossection of ply and than control the cabinet speak by using bracing and damping. what i am saying is that make the cabient live to begin with then use bracing to control the freq.you want the cabinet to be live and damping to control the level of the liveliness of teh cabinet.
even then dont expect to replicate the effect of mica filled poly. if you arei into moulding etc.. you might be able to build a box out of fiberglass matting (bonded with epoxy).
mica filled poly (braced) has a resonace that is soft and using bracing i suspect bose / jbl use the cabinet to assist the midbass (100-300hz) response of the speaker. I have exprimented with this concpet (not successfully enough) as a compensation for baffle step.
Re: About the Bose cab material
hey patrik... do we get mdf's in india.... where and how much do they cost per square feet
Binil
peterpan73 said:
hey patrik... do we get mdf's in india.... where and how much do they cost per square feet
Binil
About Bose!!
Thanks there Navin,
I am seriously exploring the possibility of constructing 'xerox' copies of the Panarays in either molded form or braced. don't know how Bose went about it (whether its braced or molded) becauae I don't own a Panaray. But I;m very eager to try... in the near future (when I'm done with my current projects).
By the way Navin.. fiberglass is a subject that has facinated me and I really hope I can get into that someday.... (the resin epoxies are so darn expensive).
Now will you be kind enough to answer my question in the Toroidal Transformer in b/lore thread about welding transformers!
I'm desperate for an answer from any of you here.
Patrick
Thanks there Navin,
I am seriously exploring the possibility of constructing 'xerox' copies of the Panarays in either molded form or braced. don't know how Bose went about it (whether its braced or molded) becauae I don't own a Panaray. But I;m very eager to try... in the near future (when I'm done with my current projects).
By the way Navin.. fiberglass is a subject that has facinated me and I really hope I can get into that someday.... (the resin epoxies are so darn expensive).
Now will you be kind enough to answer my question in the Toroidal Transformer in b/lore thread about welding transformers!
I'm desperate for an answer from any of you here.
Patrick
Thanks Vivek...
One more Q...? Any idea if u get the good old Phillips dome tweeters here in blr...?
Or are there any other locally available stuff anyone would reccomend..?
(available here in BLR.)
thanks
ajju
MDF
Hi Binil
MDF is freely available in India, go to any plywood store and ask for it, they should have it. I use it extensively for all my speaker enclosures-subs and sats. It comes in varying thicknesses, I normally use 12 mm or for subs glue two layers of 19/20mm. Its acoustically dead, and if you use the knuckle test it sounds "dead"!Indian mfrs are Nuwud and I think there are a couple of others. Imported MDF is also available, I've seen stuff from New Zealand here. I dont know about pricing.
George
Hi Binil
MDF is freely available in India, go to any plywood store and ask for it, they should have it. I use it extensively for all my speaker enclosures-subs and sats. It comes in varying thicknesses, I normally use 12 mm or for subs glue two layers of 19/20mm. Its acoustically dead, and if you use the knuckle test it sounds "dead"!Indian mfrs are Nuwud and I think there are a couple of others. Imported MDF is also available, I've seen stuff from New Zealand here. I dont know about pricing.
George
Birch Plywood??
Yes Vivek... MDF is I believe available everywhere in India and in abundance. We get that in Shillong too but without much choices in brands or country of origin. We have to make do with whatever MDF we can get.
I'm looking for Birch Ply though not for my current projects but for a future one. Is this availble in India?? Beats me!!
patrick
Yes Vivek... MDF is I believe available everywhere in India and in abundance. We get that in Shillong too but without much choices in brands or country of origin. We have to make do with whatever MDF we can get.
I'm looking for Birch Ply though not for my current projects but for a future one. Is this availble in India?? Beats me!!
patrick
Re: About Bose!!
welding transformers! why? India is a hot enough country. I have deffered plans for my 5 channel tubie (either EL34SE or EL84PP) due to heat considerations. it will have to wait till i move to a bigger apt. meanwhile i am looking at more sensitive speakers. something that can make 100db with 5W or 93db/1W. Then with a 20W amp one has 6 db headroom (I prefer 10db headroom).
meanwhileI watch the progress being made in class D amplification.
anwyay if you are interested i will dream about this for a couple of nights and let you know.
peterpan73 said:
welding transformers! why? India is a hot enough country. I have deffered plans for my 5 channel tubie (either EL34SE or EL84PP) due to heat considerations. it will have to wait till i move to a bigger apt. meanwhile i am looking at more sensitive speakers. something that can make 100db with 5W or 93db/1W. Then with a 20W amp one has 6 db headroom (I prefer 10db headroom).
meanwhileI watch the progress being made in class D amplification.
anwyay if you are interested i will dream about this for a couple of nights and let you know.
hey the trannies are cheap thats why!!
Navin.... I've been to this tranny maker in my town here last week probably the only one around here who makes the EI ones and the same guy whose made all my EI trannies till now. He calculated a final price tag of Rs.15,000 for an 300Ampere 20-0-20V tranf. Now compare the price to an off the shelf welding transformer woth a config of 450 Amps @ 50V... which costs only Rs. 2500 here in copper and smell the difference. I spoke to other welding tranny makers here and they said they can bring the secondary down to 20V for me for an additional Rs.500/- see the difference. That still makes it Rs.3000
NOw the amps that I am homebrewing at the moment are as I've metnioned before the bipolar ones. Again, if I were to use seperate EI trannies for each 100W RMS stage @ Rs.250 something for each, you can multiply that by 10 and you get Rs.2500. I am hoping to use the welding tranny as I have upgradation plans such as increasing load later when I power up other Amps that I will be building. In building amps PSUs always cost most. It was foresight that had caused me to think of the welding tranny... economies of scale or whatever. Hoping to make it a once and for all investment.
In live sound reinforcement you need lots of power... lots of it... especially in free field use.
Another thing (who knows) I can even use the same setup to double up for my welding purposes at home. All I will need is bypass the rectifier stage(a lug type discrete diode rect.bridge is planned) and filter circuitry and connect the welding rod from the AC output of the tranny or even after the rectifier stage if something like the IRF 200MT40KB Bridge is used (max 200A).
Alternatively I would have to spend on lots of individual trannies for every 100W to 500W amp that I build.
Now will someone tell me whether 9,00,000mfd caps will do for the cap filter and where I could get them(in parallel) or get one single cap or even better, whether there are alternatives for the filter.
Patrick
Navin.... I've been to this tranny maker in my town here last week probably the only one around here who makes the EI ones and the same guy whose made all my EI trannies till now. He calculated a final price tag of Rs.15,000 for an 300Ampere 20-0-20V tranf. Now compare the price to an off the shelf welding transformer woth a config of 450 Amps @ 50V... which costs only Rs. 2500 here in copper and smell the difference. I spoke to other welding tranny makers here and they said they can bring the secondary down to 20V for me for an additional Rs.500/- see the difference. That still makes it Rs.3000
NOw the amps that I am homebrewing at the moment are as I've metnioned before the bipolar ones. Again, if I were to use seperate EI trannies for each 100W RMS stage @ Rs.250 something for each, you can multiply that by 10 and you get Rs.2500. I am hoping to use the welding tranny as I have upgradation plans such as increasing load later when I power up other Amps that I will be building. In building amps PSUs always cost most. It was foresight that had caused me to think of the welding tranny... economies of scale or whatever. Hoping to make it a once and for all investment.
In live sound reinforcement you need lots of power... lots of it... especially in free field use.
Another thing (who knows) I can even use the same setup to double up for my welding purposes at home. All I will need is bypass the rectifier stage(a lug type discrete diode rect.bridge is planned) and filter circuitry and connect the welding rod from the AC output of the tranny or even after the rectifier stage if something like the IRF 200MT40KB Bridge is used (max 200A).
Alternatively I would have to spend on lots of individual trannies for every 100W to 500W amp that I build.
Now will someone tell me whether 9,00,000mfd caps will do for the cap filter and where I could get them(in parallel) or get one single cap or even better, whether there are alternatives for the filter.
Patrick
About the monster PSU filter
Navin... Hey this is not a living room amp OK .. so I'm not playing it in the house. I'm planning to make the PSU like a standalone or something on wheels just like a welding machine.
I think its more feasible and efficient to use choke filters than caps. But I'm waiting for a reply from somebody technically saner than me, because like I've said before I'm just a novice at this.
Somebody please say something.
Patrick
Navin... Hey this is not a living room amp OK .. so I'm not playing it in the house. I'm planning to make the PSU like a standalone or something on wheels just like a welding machine.
I think its more feasible and efficient to use choke filters than caps. But I'm waiting for a reply from somebody technically saner than me, because like I've said before I'm just a novice at this.
Somebody please say something.
Patrick
hi
hi
so far as my knowledge goes the bose drivers use
mica reinforced pp , the frames are formed in mica reinforced pp and the top plates insert moulded , this reduces driver resonances as claimed by bose
there are 100 s of ways to reduce driver frame resonances , what he has not mentioned is that such moulded frames solves the resonance problem in the 802 design the best
why
as these drivers are so compactly loaded the wall and the thickness of the cabinet is not large
and the cabinet itself is made of plastic type material
in such a situtation using metal frames will be diffcult and cost involving gaskets would be need to be placed for driver mounting
where as the mica + pp frames blend into the enclosure material wise
(navin will be aware , joining to totally dissemilar materials is difficult , speacilly in an enviorment where there is a lot of vibrations , screws of exact material , torque ets ets , making assembling costs high)
-------------------------------------------------------------------------------
this is done by penshien of taiwan actually for bose (i dont know if it is right to give such trade news here ! )
the materials of the cabinet are not exactly injection mould material infact these moulds and the moulding material is moer like a pressure cast / formed
i have the list of the exact technical name , i mean compound
and their resonance frequencies
in fact it is a chart which includes mdf , particle board , plywoods (quite a few types ) to all these latest materials
notes on their application
these are of technical nature and manufacturer oriented where it cannot be replicated without involving heavy costs
why ?
big injection moulds require
ejection capabality , cavity of the mould generally ddoes not include further cavitys
if some one studies the 802 there are 8 seperate cavities
if this was a injection mould the cabinet will be very difficult to eject
there for the material flows more or less like a die cast
in order to make such cabinets first we have to locate - who is doing such moulding
as the moulding process is different and quantites are low
then getting the moulding material will not be a problem , for some one who has the money to shell out firstly for such a big mould
plastic moulding is of great interest to me and i have made quite a few moulds such discussions on the design of the mould and its ejection procedure are wellcome
in all this the good news is that forgings of taiwan is moulding the cabinets for bose
anyone with brains can get these cabinets from them at around 6000 to 8000 each , drivers from me 1000 X 8 and have bose ready ! prior to investing in the moulds
then market this india wide check out customer base
then slowly mould the cabinet / costs for such a moulding will be around rs 2000 each - a rough guess ! and reduce production costs
suranjan
hi
so far as my knowledge goes the bose drivers use
mica reinforced pp , the frames are formed in mica reinforced pp and the top plates insert moulded , this reduces driver resonances as claimed by bose
there are 100 s of ways to reduce driver frame resonances , what he has not mentioned is that such moulded frames solves the resonance problem in the 802 design the best
why
as these drivers are so compactly loaded the wall and the thickness of the cabinet is not large
and the cabinet itself is made of plastic type material
in such a situtation using metal frames will be diffcult and cost involving gaskets would be need to be placed for driver mounting
where as the mica + pp frames blend into the enclosure material wise
(navin will be aware , joining to totally dissemilar materials is difficult , speacilly in an enviorment where there is a lot of vibrations , screws of exact material , torque ets ets , making assembling costs high)
-------------------------------------------------------------------------------
this is done by penshien of taiwan actually for bose (i dont know if it is right to give such trade news here ! )
the materials of the cabinet are not exactly injection mould material infact these moulds and the moulding material is moer like a pressure cast / formed
i have the list of the exact technical name , i mean compound
and their resonance frequencies
in fact it is a chart which includes mdf , particle board , plywoods (quite a few types ) to all these latest materials
notes on their application
these are of technical nature and manufacturer oriented where it cannot be replicated without involving heavy costs
why ?
big injection moulds require
ejection capabality , cavity of the mould generally ddoes not include further cavitys
if some one studies the 802 there are 8 seperate cavities
if this was a injection mould the cabinet will be very difficult to eject
there for the material flows more or less like a die cast
in order to make such cabinets first we have to locate - who is doing such moulding
as the moulding process is different and quantites are low
then getting the moulding material will not be a problem , for some one who has the money to shell out firstly for such a big mould
plastic moulding is of great interest to me and i have made quite a few moulds such discussions on the design of the mould and its ejection procedure are wellcome
in all this the good news is that forgings of taiwan is moulding the cabinets for bose
anyone with brains can get these cabinets from them at around 6000 to 8000 each , drivers from me 1000 X 8 and have bose ready ! prior to investing in the moulds
then market this india wide check out customer base
then slowly mould the cabinet / costs for such a moulding will be around rs 2000 each - a rough guess ! and reduce production costs
suranjan
Wonderful writeup
Hi Suranjan,
Well thanx a lot... that was more than informative.. its was enlightening. Unlike your other posts... I took great care to read every thing this time. OK tell us who are these people supplying Bose these molded cabs from Taiwan??
Patrick
Hi Suranjan,
Well thanx a lot... that was more than informative.. its was enlightening. Unlike your other posts... I took great care to read every thing this time. OK tell us who are these people supplying Bose these molded cabs from Taiwan??
Patrick
hi
patrik
i have already mentioned which co s make these for bose ,
every proper driver amnufacturer oem supplier s more or less should be knowing them
since they only deal in huge quantities (and the best brands)
l doubt they will hand out their web site access password
unless
you impress them with knowledge up to their standards or have a very good order
its the same with them as is with me - i guess
i can show you their catalogues when you come to cal
take care
suranjan
patrik
i have already mentioned which co s make these for bose ,
every proper driver amnufacturer oem supplier s more or less should be knowing them
since they only deal in huge quantities (and the best brands)
l doubt they will hand out their web site access password
unless
you impress them with knowledge up to their standards or have a very good order
its the same with them as is with me - i guess
i can show you their catalogues when you come to cal
take care
suranjan
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