isobarik speaker design

[moody]

boot camp?

 

Not on a G4

 

I have someone giving me a PC shortly, for those few programs that I just can't run.

[boseengineer]

I guess if the air space between the two drivers is really small, the cones will more or less move together. So you could model the whole thing as a single driver with double the motor force, double the moving mass, half the DC resistance and the same cone area.

 

However, that may be to simple an assumption. The air volume between the speakers is not trivial, and especially close to the tuning frequency of the horn you will see a significant velocity differential between the drivers and hence your "isobaric" assumption goes out the window at low frequencies.

[agedhorse]

I guess if the air space between the two drivers is really small, the cones will more or less move together. So you could model the whole thing as a single driver with double the motor force, double the moving mass, half the DC resistance and the same cone area. However, that may be to simple an assumption. The air volume between the speakers is not trivial, and especially close to the tuning frequency of the horn you will see a significant velocity differential between the drivers and hence your "isobaric" assumption goes out the window at low frequencies.

 

That's exactly how I would begin the approach, but the approximation may indeed be flawed by the less than perfect coupling between the cones. Springs behave as a solid coupling until they begin to behave like springs

[Craig Vecchione]

 

Yea lucky us fitzmaurice bozos don't know what we're talking bout...maybe we oughta read and learn a little more...you giving classes?

 

 

Sure. Lesson 1 is how to admit when you're wrong.

[moody]

 

Sure. Lesson 1 is how to admit when you're wrong.

 

 

I think the reason that this sort of design wouldn't appeal to the fitzmaurice league is the it is completely at odds with their design philosophy.

 

Fitzmaurice: Cheap parts, lots of labour, huge boxes.

Isobarik: Expensive parts, still lots of labour but not as bad as Fitzmaurice, Very small boxes.

 

I only barely considered it because I have the drivers sitting at home doing nothing. I'm thinking that a non horn box would probably be easier to model. I'm also thinking that the drivers I have might be difficult for this as it would mean a cabinet of 800 watts RMS and I don't have any amps to match.

[Craig Vecchione]

 

I think the reason that this sort of design wouldn't appeal to the fitzmaurice league is the it is completely at odds with their design philosophy. Fitzmaurice: Cheap parts, lots of labour, huge boxes. Isobarik: Expensive parts, still lots of labour but not as bad as Fitzmaurice, Very small boxes. I only barely considered it because I have the drivers sitting at home doing nothing. I'm thinking that a non horn box would probably be easier to model. I'm also thinking that the drivers I have might be difficult for this as it would mean a cabinet of 800 watts RMS and I don't have any amps to match.

 

 

Less power is okay, you can add more later. The decision should be based on whether you need a box that's really small and still has low extension. It won't be a light box, either, but that's the tradeoff; all we ever really do is push the same squares around the board...

[preacherman672]

Sure. Lesson 1 is how to admit when you're wrong.

 

So you're finally gonna admit it?? Go ahead I"m all ears

 

:poke:

[preacherman672]

 

I think the reason that this sort of design wouldn't appeal to the fitzmaurice league is the it is completely at odds with their design philosophy. Fitzmaurice: Cheap parts, lots of labour, huge boxes. Isobarik: Expensive parts, still lots of labour but not as bad as Fitzmaurice, Very small boxes. I only barely considered it because I have the drivers sitting at home doing nothing. I'm thinking that a non horn box would probably be easier to model. I'm also thinking that the drivers I have might be difficult for this as it would mean a cabinet of 800 watts RMS and I don't have any amps to match.

 

 

There are always tradeoffs. I've modelled probably 50 or so drivers iso in WinISD and the trade offs weren't worth it to me. YMMV

 

Les

[moody]

 

Less power is okay, you can add more later. The decision should be based on whether you need a box that's really small and still has low extension. It won't be a light box, either, but that's the tradeoff; all we ever really do is push the same squares around the board...

 

 

The thing is, that's exactly what I want. At the moment the subs I have are massive - and I drive a small van, hence they take up close to half the available space. I'm happy with them but I was thinking of more power for the same cabs - the alternative would be smaller cabs and more of them.

[Craig Vecchione]

So you're finally gonna admit it?? Go ahead I"m all ears :poke:

 

Didn't I just explain that I was misinterpreting what the guys were talking about? Oh....wait a minute....that's not what you're on about, now is it? You're still sore that I think the Tuba isn't what Bill claims it is! Oh, silly me! And to think that someone who calls himself a preacher would carry a grudge for what is it now? Three years? Four? And for something as trivial as an opinion. Shame, really it is. No wait, it's a sin....pride is a sin, isn't it? One of the 7 deadlies.... Hmmm.....

 

[Craig Vecchione]

 

The thing is, that's exactly what I want. At the moment the subs I have are massive - and I drive a small van, hence they take up close to half the available space. I'm happy with them but I was thinking of more power for the same cabs - the alternative would be smaller cabs and more of them.

 

 

Since you have the drivers, if you have the materials maybe it's worth a try. Just keep in mind they may not be a loud as you need. The point of this design is extension, which may not be as important as overall efficiency.

[moody]

 

Since you have the drivers, if you have the materials maybe it's worth a try. Just keep in mind they may not be a loud as you need. The point of this design is extension, which may not be as important as overall efficiency.

 

 

Well, I have the drivers, I have an enormous amount of plywood (5 7 and 11 ply).

 

I still don't know if I'm going to even look at doing this, its an idea. Probably more likely to figure out some smaller monitors and things before I even think of doing it.

[moody]

OK, still on a fact finding type thing. (from square one I have no plans of doing anything).

 

What would happen if you made a speaker cab that was only a Isobarik chamber, one woofer facing forward out the front, one backwards out the back. I assume that it would sound the same forwards or backwards, I also assume that there would be quite a lot of cancelation?? Both woofers would act as if they were in open space?

 

What would happen if you did the same thing then sealed one side, sealed cabinet the size of the speaker cone??

 

I assume that adding additional drivers wouldn't add any benefit? e.g. 4 woofers making 3 Isobarik chambers, same surface area, more power handling but no other benefit?

[Craig Vecchione]

 

OK, still on a fact finding type thing. (from square one I have no plans of doing anything). What would happen if you made a speaker cab that was only a Isobarik chamber, one woofer facing forward out the front, one backwards out the back. I assume that it would sound the same forwards or backwards, I also assume that there would be quite a lot of cancelation?? Both woofers would act as if they were in open space? What would happen if you did the same thing then sealed one side, sealed cabinet the size of the speaker cone?? I assume that adding additional drivers wouldn't add any benefit? e.g. 4 woofers making 3 Isobarik chambers, same surface area, more power handling but no other benefit?

 

 

You'd have essentially an open-back cabinet, with the characteristic limited low frequency response. If I'm then understanding your second version, you are creating a very limited air space that's essentially the volume of the cone. The air trapped here would create a very small sealed cabinet...the cone travel of this speaker would be much more limited than in the more conventional isobarik design, further affecting the overall efficiency, tone and especially low frequency response.

 

As for the last version with multiple chambers, I think the added power handling would be wasted by limitations in cone excursion (at least for low frequency) and size. But that's just a WAG.

[preacherman672]

Didn't I just explain that I was misinterpreting what the guys were talking about? Oh....wait a minute....that's not what you're on about, now is it? You're still sore that I think the Tuba isn't what Bill claims it is! Oh, silly me! And to think that someone who calls himself a preacher would carry a grudge for what is it now? Three years? Four? And for something as trivial as an opinion. Shame, really it is. No wait, it's a sin....pride is a sin, isn't it? One of the 7 deadlies.... Hmmm.....

 

Haha you're the one keeps bringing it up must be a sore spot for you. Especially after all that scientific testing you did...

 

:poke:

[preacherman672]

 

OK, still on a fact finding type thing. (from square one I have no plans of doing anything). What would happen if you made a speaker cab that was only a Isobarik chamber, one woofer facing forward out the front, one backwards out the back. I assume that it would sound the same forwards or backwards, I also assume that there would be quite a lot of cancelation?? Both woofers would act as if they were in open space? What would happen if you did the same thing then sealed one side, sealed cabinet the size of the speaker cone?? I assume that adding additional drivers wouldn't add any benefit? e.g. 4 woofers making 3 Isobarik chambers, same surface area, more power handling but no other benefit?

 

 

There's a company that uses 6 18's in a cab that looks similar to a standard double 18 (only deeper). I believe it's configured with 3 drivers in iso right behind each other per side. Weighs bout 300 i think also. and they are neo drivers.

[Craig Vecchione]

Haha you're the one keeps bringing it up must be a sore spot for you. Especially after all that scientific testing you did... :poke:

 

Only time I mention that speaker is when someone asks about it. But it is a little creepy that you only, and always, seem to show up when the word "fitzmaurice" is in a thread.

 

Why would I need "scientific testing"? Doesn't Bill already have comprehensive results posted? I built them to see what sort of plans you get for 10 bucks and to decide whether they lived up to the claim of blowing away JBL SR-X. If there's a scientific quantification of "blowing away" that can be measured, by all means let me know.

 

By the way, when you go back to post all of this and have a chuckle with your little friends, tell Bill I'm still waiting for the registration email for my account access to his forums. For some reason I never received the confirmation email. Huh.....

[preacherman672]

 

Only time I mention that speaker is when someone asks about it. But it is a little creepy that you only, and always, seem to show up when the word "fitzmaurice" is in a thread. Uh no one else really pays you any attention outside of HC forums? is prolly the reason lol and evertime someone brings up Bill's designs they state your test as the definitave answer to all questions. I hardly ever post here but read almost all the threads Why would I need "scientific testing"? Doesn't Bill already have comprehensive results posted? I built them to see what sort of plans you get for 10 bucks and to decide whether they lived up to the claim of blowing away JBL SR-X. If there's a scientific quantification of "blowing away" that can be measured, by all means let me know. some charts of your testing woulda been nice but oh well i'm not wanting to argue again By the way, when you go back to post all of this and have a chuckle with your little friends, tell Bill I'm still waiting for the registration email for my account access to his forums. For some reason I never received the confirmation email. Huh..... Do you really think you are a major topic of conversation? Wow. Now that's some ego.

 

 

LW

[Craig Vecchione]

Originally Posted by Craigv Only time I mention that speaker is when someone asks about it. But it is a little creepy that you only, and always, seem to show up when the word "fitzmaurice" is in a thread. Uh no one else really pays you any attention outside of HC forums? is prolly the reason lol and evertime someone brings up Bill's designs they state your test as the definitave answer to all questions. I hardly ever post here but read almost all the threads Why would I need "scientific testing"? Doesn't Bill already have comprehensive results posted? I built them to see what sort of plans you get for 10 bucks and to decide whether they lived up to the claim of blowing away JBL SR-X. If there's a scientific quantification of "blowing away" that can be measured, by all means let me know. some charts of your testing woulda been nice but oh well i'm not wanting to argue again By the way, when you go back to post all of this and have a chuckle with your little friends, tell Bill I'm still waiting for the registration email for my account access to his forums. For some reason I never received the confirmation email. Huh..... Do you really think you are a major topic of conversation? Wow. Now that's some ego.

 

No, I have no ego in this place, and I never consider myself a topic of conversation anywhere. It's a web forum, so it wouldn't matter if I was.

 

I wanted to explain in Bill's forum that the guy who I gave a couple days banning was wrong about what he posted there. I knew damned well that I'd get jumped, but I figured maybe if I posted my side of things there would be some chance of burying this hatchet. But it's more than clear to me that this won't happen.

 

I didn't like the speakers...they weren't close enough in performance to my SR-X to make the purchase of testing hardware and software worth my money, or for that matter, the time....I had spent a good week of evenings building them. They aren't bad subs....I've said this many times but you ignore that...they just don't meet the claims made of them. I was also very disappointed with the plans themselves...another issue that was never addresses to me by you or anyone else from Bill's group who posted in this forum.

 

But that was it...I wasn't impressed, and I had problems with the plans. One guy's opinion. Why this is important to you to the point of harrassing me about it years later is beyond me. It's not my ego here, it's apparently yours.

[preacherman672]

 

No, I have no ego in this place, and I never consider myself a topic of conversation anywhere. It's a web forum, so it wouldn't matter if I was. I wanted to explain in Bill's forum that the guy who I gave a couple days banning was wrong about what he posted there. I knew damned well that I'd get jumped, but I figured maybe if I posted my side of things there would be some chance of burying this hatchet. But it's more than clear to me that this won't happen. I didn't like the speakers...they weren't close enough in performance to my SR-X to make the purchase of testing hardware and software worth my money, or for that matter, the time....I had spent a good week of evenings building them. They aren't bad subs....I've said this many times but you ignore that...they just don't meet the claims made of them. I was also very disappointed with the plans themselves...another issue that was never addresses to me by you or anyone else from Bill's group who posted in this forum. But that was it...I wasn't impressed, and I had problems with the plans. One guy's opinion. Why this is important to you to the point of harrassing me about it years later is beyond me. It's not my ego here, it's apparently yours.

 

 

 

All that sounds really good an nice and friendly Craig but the fact of the matter is you brought it up in this thread and tried to disguise the fact by mispelling the name.

 

You claim now that they are good subs but you have offered before to give them away to anyone who would take them and called them a prison for your Beta 10's

 

If you truly want bury the hatchet then quit bringing it up in a seemingly derogatory manner.

 

You brought it up, I responded. Those are the facts in this thread. Where's the ego trip on my part?

 

The sole reason I keep this up is because there are many people out there who can greatly benefit from Bill's designs and who have lots more time than cash.

 

Many of these people are in the church realm and have carpenters and woodworkers in their congregation who will donate time, but not necesarily money. Not saying it's the way it should be, just saying how it is.

 

Bill's plans give them the opportunity to have top notch speakers at least and give some people the opportunity work in ministry for the church.

 

BTW before I ever built any speakers of Bill's I thoroughly read your posts on your build. I decided against building them at the time but came back later just to give them a shot.

 

Was not drinking any Kool-Aid or anything like you have claimed in the past. Built the cabinets but used speakers I knew I could re-use in some BR cabs I already had if the project flopped.

 

Expected average performance but was greatly surprised by the outcome. Built more and was really impressed.

 

For reference I run sound for a sound company that does most of the festivals in this small region of north Lousiana, Miss, AR, and east Texas. We are racks and stacks only but I have run sound with most all major brands of speakers.

 

I stand behind my claims on Bill's speakers and his.

 

Les Webb

[agedhorse]

Maybe the real question to ask is "What would Jesus build?"

[Craig Vecchione]

I didn't disguise anything...it's a running joke here and in the bass forum that if you spell "Fitzmaurice" someone magically shows up to protect and defend. It's like saying "Beetlejuice!" three times. And all I did was say that I was surprised Bill wasn't all over the isobarik design. You started the smack-talking, and why is that? Are you Bill's bitch? I didn't mention your name anywhere.

 

I didn't write here that the speakers are good, so claiming that I'm "now" saying this isn't true. I said they aren't a bad design, and that's what I've written many times over the years.

[Craig Vecchione]

Maybe the real question to ask is "What would Jesus build?"

 

Buddy Christ says, "Yeahhhhhh!"

 

[moody]

My thread has gone off topic

 

I don't care!!

 

My questions were answered

 

I'm quite happy with the result

 

And I get to watch another famous fitzmaurice battle

 

Sits down to watch the action

[agedhorse]

I kind of like Craig's statue too.