need help with isobaric wiring

johnny45

johnny45

Audiophyte
i need help iv run into a issue with my sub build



ive got two dual 4 ohm subs that i need to wire up for use in a isobaric clam shell config but need it to be at 2 ohm at the amp so i could deliver 775watts to the config ,but now in parallel they would equal a 1 ohm load which my crown xls 1502 cant do



so my two ? are if i wire them in series, then the speakers wired in parallel like in this 12volt Diagram

2_4ohm_dvc_4ohm.gif



1. how do i make the second driver out of phase ( this i dont know )



2. the driver specs are this each is has two 4ohm voice coils each rated for 400watt for combind total of 800watts with 1600watt peak (the xls 1502 4ohm out is 525 but i'd like the higher spl that i'd get with 775watt ) so could i do this
2_subs_DVC_4_ohm_2ch (1).jpg

an wire the second sub out of phase an set the amp for parallel output (same sig to both) an put both drivers in the isobaric build an still have the desired iso effect (ya know the push - pull )


if need be id buy a 2nd amp for the 2nd build ,my plan was originally to two seperate sub builds with two drivers per box in isobaric config run off my one crown xls 1502 with the intended builds run from the two channell output so each could get 775watts with one on each side of my ht room, but because i didnt know that wiring two dual 4ohm subs in parallel would hit 1ohm



for ref this is an exsploded view of my design


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9 (4).png
9 (3).png
9 (2).png
9 (1).png
 
Last edited:
Verdinut

Verdinut

Audioholic Samurai
i need help iv run into a issue with my sub build



ive got two dual 4 ohm subs that i need to wire up for use in a isobaric clam shell config but need it to be at 2 ohm at the amp so i could deliver 775watts to the config ,but now in parallel they would equal a 1 ohm load which my crown xls 1502 cant do



so my two ? are if i wire them in series, then the speakers wired in parallel like in this 12volt Diagram

View attachment 34304


1. how do i make the second driver out of phase ( this i dont know )



2. the driver specs are this each is has two 4ohm voice coils each rated for 400watt for combind total of 800watts with 1600watt peak (the xls 1502 4ohm out is 525 but i'd like the higher spl that i'd get with 775watt ) so could i do this
View attachment 34305




an wire the second sub out of phase an set the amp for parallel output (same sig to both) an put both drivers in the isobaric build an still have the desired iso effect (ya know the push - pull )




for ref this is an exsploded view of my design


View attachment 34306View attachment 34307View attachment 34308View attachment 34309View attachment 34310
Don't bridge the XLS 1502. Just connect one sub to one amp and the second to the other channel. This way, each amp will drive a 2 ohm load and provide 775w of power.
EDIT: The subs operate in push-pull, then just invert the connections for one of the drivers.
 
johnny45

johnny45

Audiophyte
Don't bridge the XLS 1502. Just connect one sub to one amp and the second to the other channel. This way, each amp will drive a 2 ohm load and provide 775w of power.
EDIT: The subs operate in push-pull, then just invert the connections for one of the drivers.
thanks an i was'nt planing to bridge the crown ,but your saying that Just connecting one sub to one amp and the second to the other channel would still produce the isobaric effect
 
TLS Guy

TLS Guy

Audioholic Slumlord
thanks an i was'nt planing to bridge the crown ,but your saying that Just connecting one sub to one amp and the second to the other channel would still produce the isobaric effect
Yes, it would. However I don't understand your speaker design at all. An isobarik speaker can have two drivers connected by one tunnel and one speaker facing the room and the other's rear the tuned cavity. However the drivers are IN and NOT out of phase as you would have the drivers facing the same way.

Again you can have each of the rear of those drivers see its own closed cavity and a ported cavity between them. The drivers would again be in phase.

If you are going to have them out of phase, then the back of one driver must face a sealed cavity and the back of the other a ported one. This latter though is not an isobarik design but a dual coupled cavity design. I don't see any ports here. I really don't understand your design at all at this time.

The advantage of using an isobarik speakers is the cabinet volume is halved because VAS is halved. Sensitivity is down by 3 db. Driver cost is doubled for less output than one driver.
 
johnny45

johnny45

Audiophyte
thanks i understand now ,i dont have the best software for modeling cabs for design i was going off what i have an web images for concept
 
johnny45

johnny45

Audiophyte
does anyone have any experience with soundeasy 23 software and if its doable to model isobarik sub builds would it help in such designing

id like some opitions on whether or not take the plung for the 200+ price tag
 
everettT

everettT

Audioholic Ninja
does anyone have any experience with soundeasy 23 software and if its doable to model isobarik sub builds would it help in such designing

id like some opitions on whether or not take the plung for the 200+ price tag
I use bassbox pro and found it easy to use with a good database.
 
TLS Guy

TLS Guy

Audioholic Slumlord
thanks i understand now ,i dont have the best software for modeling cabs for design i was going off what i have an web images for concept
I'm not sure you do understand. I have a strong feeling you are completely confusing isobarik and coupled cavity alignments.

Isibarik, just means two drivers are coupled in such a way that VAS is halved and therefore cabinet volume is halved. It never is that good because of the volume of the connecting tunnel which has to be added to the tuning volume.

Now an isobarik speaker can have an out facing driver or be a coupled cavity arrangement and so can a single speaker.

The only advantage of an isobarik speakers is cabinet volume reduction, it is all down hill after that.

I have a feeling that you think coupled cavity designs are isibarik, but they are usually not and do not have to be.

Coupled cavity designs were developed to control Q and produce a tight bass. However there is a close relationship between Q and bandwidth so that the lower the Q the lower the bandwidth.

Enthusiasm for couple cavity designs has waned unless you are Bose. They are high Q with higher bandwidth, which is why their bass is so ponky.

In the AVR world the LFE effects goes out to 120 Hz. It is impossible to design a good coupled cavity speaker with a bandwidth from 20 Hz to 120 Hz. In addition you only have port radiation, nothing from the cone or cones. So that is why enthusiasm has waned for this approach.

Isobariks are not popular as you double your driver cost, and loose output at the same time as gaining zero bass extension. I stress again that it is just a means of reducing cabinet volume at the expense of the above. It is nothing more than that.

If you want an isobarik design here is one that I did.

This would the arrangement. The drivers are coupled by the air space between them, and they are wired in phase.

1582899421156.png


Here is a picture of an old KEF coupled cavity design from an era when it was popular. This design is coupled cavity, but it is NOT isobarik.



Those speakers would be wired out of phase.

I really think it was mainly the AV era and the need for wider bandwidth than coupled cavity can provide that killed it.

After all this I have no idea what you are trying to achieve and I'm not convinced you do either.
 
johnny45

johnny45

Audiophyte
HEY JUST TO CLEARIFY IN MY ISOBARIC CLAMSHELL SETUP AN IM USING WINISD TO MODEL FOR BOX AN DRIVER AN IM WONDERING DOES THIS BOX DESIGN
vented-cone-to-cone-isobaric.jpg


COUNT AS A VENTED 6TH ORDER BANSPASS OR JUST REGULAR VENTED THE READ I GET WITH MY CHOSEN DRIVERS IS (EBP = 56.6 )IN WINISD AN THE LITTLE BLUE BAR IS HALF WAY UP ON THE LITTLE SCALE AN THE AUTO ASSIGNED DESIGN TYPE IS LISTED AS JUST VENTED IS THAT RIGHT

MY BOX AN DRIVER SPECS IS THIS

TWO - AUDIOPIPE TXXBD1 15IN
BOX WITH 3.853 CUBIC FT TUNED TO 20HZ WITH A 16.3IN BY 1IN BY 25IN
IM PLANING TO FEED EACH 775WATT AN THIS IS FOR USE IN A HOME THEATHER AN SHOULD THE EXSPOSDED DRIVE BE FACING THE WALL OR AIMING AWAY FROM IT ?

THE REASON IV CHOSEN THIS SETUP IS IT ACCORDING TO WINISD CONTROLES MY CONE EXCURSION WHEN 775WATTS IS PUMPED INTO IT ,CONE EXCURSION IS BADLY EXCEEDED WHEN JUST USING ONE DRIVER, WITH TWO LIKE IN THE DEPICTED IMAGE IST UNDER CONTROL AN WITH MY OUTLAW RECEVIERS
panoramic eq an high pass filter at least in the software i get a smooth response down to 20hz
 

Attachments

everettT

everettT

Audioholic Ninja
HEY JUST TO CLEARIFY IN MY ISOBARIC CLAMSHELL SETUP AN IM USING WINISD TO MODEL FOR BOX AN DRIVER AN IM WONDERING DOES THIS BOX DESIGN
View attachment 34318

COUNT AS A VENTED 6TH ORDER BANSPASS OR JUST REGULAR VENTED THE READ I GET WITH MY CHOSEN DRIVERS IS (EBP = 56.6 )IN WINISD AN THE LITTLE BLUE BAR IS HALF WAY UP ON THE LITTLE SCALE AN THE AUTO ASSIGNED DESIGN TYPE IS LISTED AS JUST VENTED IS THAT RIGHT

MY BOX AN DRIVER SPECS IS THIS

TWO - AUDIOPIPE TXXBD1 15IN
BOX WITH 3.853 CUBIC FT TUNED TO 20HZ WITH A 16.3IN BY 1IN BY 25IN
IM PLANING TO FEED EACH 775WATT AN THIS IS FOR USE IN A HOME THEATHER AN SHOULD THE EXSPOSDED DRIVE BE FACING THE WALL OR AIMING AWAY FROM IT ?

THE REASON IV CHOSEN THIS SETUP IS IT ACCORDING TO WINISD CONTROLES MY CONE EXCURSION WHEN 775WATTS IS PUMPED INTO IT ,CONE EXCURSION IS BADLY EXCEEDED WHEN JUST USING ONE DRIVER, WITH TWO LIKE IN THE DEPICTED IMAGE IST UNDER CONTROL AN WITH MY OUTLAW RECEVIERS
panoramic eq an high pass filter at least in the software i get a smooth response down to 20hz
That driver really isn't suited for home audio. It's a "boom" driver and from what I can see would be sloppy. DR.Mark will know before I get home to check, but from specs I found it's not high fidelity
 
TLS Guy

TLS Guy

Audioholic Slumlord
That driver really isn't suited for home audio. It's a "boom" driver and from what I can see would be sloppy. DR.Mark will know before I get home to check, but from specs I found it's not high fidelity
I can't find the T/S parameters of that driver. However car sub drivers very, very seldom make good home audio sub drivers.

The picture you posted is impractical, cosmetically awful and likely to cause injury to property and person.

An isobarik reducing driver excursion, makes no sense at all, and it won't. In fact it will make it worse as you need more cone excursion for the same spl.

A 6th order ported alignment is a bad idea. They are very hard to implement and run just about any driver out of xmax and damage it.

KEF had a top of the line 6th order speaker some years ago. It was short lived after they had to deal with all the warranty claims.

You can build an excellent sub without all this complication.

The rule "keep it simple stupid" very much applies here. That is probably my most important piece of advice to you right now.
 

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