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Author Topic: Gona try this another way  (Read 2822 times)

Mike Spade

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Gona try this another way
« on: May 14, 2018, 09:31:44 pm »

Okay since everybody seems so concerned about my sound system and can't stay on subject, lets try this another way.

Lets pretend I have zero gear.

Lets pretend have a limited budget so buying new higher powered subs or amps isn't a option.

Lets pretend I have limits on power draw so buying a new high wattage amp and 18s isn't a option even if I had the budget.

Lets pretend I have been donated a 500w rms amp and two 600w rvp 18s.

Lets pretend I have unlimited storage so cab size doesn't matter, it doesn't need to be small or compact.

Lets pretend I wanted it to go as low as 30hz.

Lets pretend all designs are on the table, bandpass, orders, reflex ect.

Lets pretend you got unlimited wood and case building supplies.

What kind of case would you make for these for sub bass above 30hz?
https://www.rockvilleaudio.com/rvp18w8/

Would you use a bass reflex design like yorkvilles sw1000 or communitys s218 or "the gsub"? If not, why not?

Would you use a different or more compact design like a sb1000? If not, why?

Do you know of any already made dual 18 cases made by any manufacturer that is around the same wattage of 1000-1200w rms with good results?

Looking for constructive chat here, not people telling me not to do it or not to bother, since this is just talking, I haven't done anything yet.

Also don't want to start a wattage debate, these subs have been chosen due to being dirt cheap as the first reason and inspired by the VBSS I thought to myself there must be a way to get the most possible out of these drivers in much the same way.
http://www.avsforum.com/forum/155-diy-speakers-subs/2226642-v-b-s-s-diy-subwoofer-design-thread.html

« Last Edit: May 14, 2018, 10:34:39 pm by Mike Spade »
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David Winners

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Re: Gona try this another way
« Reply #1 on: May 14, 2018, 10:35:45 pm »

I would suggest you buy a pile of these. The pesky math is already done, and I don't think you could build the cabinets for that price. If you have spare drivers, that's a good thing.

Edited to add a word
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Mike Spade

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Re: Gona try this another way
« Reply #2 on: May 14, 2018, 10:46:55 pm »

I would suggest you buy a pile of these. The pesky math is already done, and I don't think you could build the cabinets for that price. If you have spare drivers, that's a good thing.

Edited to add a word

I've actually messaged rockville about those exact cabs asking for the driver specs, thinking they may be a option to look at.

They told me its NOT the same 18 they are selling as singles and refused to give me anymore information or specs.

The biggest thing about those cabs that is a turn-off to me is that they are MDF and I do monthly outdoor events so they would have to be decarpited and bedlined to survive and tbh I dont trust mdf nearly as much as birch... I've had some mdf cases and they fall apart and get damaged, my crew is kinda rough sometimes. They also got no corners, suppose could always buy some.. but I mean I'm a wood worker I know I could make something better if I made the plans first. All my double 15s and 18s have 2 casters on the back/bottom with handles on the top so you can lean them back, I'd like to do this for my double 18 designs too, but you can do that to any design by re calculating the volume and box size.

So these drivers I have are NOT spare drivers for that case!

Still need to make a case, plus this seems like it could be a cool project making a double 18! Once I figure out what I want I'll prob make a test box out of mdf (cuz its cheap) and then make a birch one after if I like it.
« Last Edit: May 14, 2018, 10:49:46 pm by Mike Spade »
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Luke Geis

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Re: Gona try this another way
« Reply #3 on: May 14, 2018, 11:48:30 pm »

Without a speaker designer software, it is at best a guess. It seems as if it will go down to 30hz. so it should be possible to create a box with it that gets relatively low. However, I don't believe some of its specs.

First it is a stamped steel frame. It claims 101db @ 1w 1M for sensitivity. Furthermore it claims sub 30hz capability with a 3" coil. These are not typical specs for a driver with teh price tag this one has. It states 1,200 watts as being its peak rating, and 600 watts is its RMS wattage. Usually the peak rating is 4x the RMS, but that is not relevant in this case really. Based on the specs you could only supply 600 watts total per speaker so a dual 18" cabinet would prefer to see about 1,200 watts. You only have 1000 watts as far as I can tell?

Given what it states, this speaker would only be capable of 128.8db at 1meter with 600 watts of power. Double that power to 1,200 watts and you only gain 3db for 131.8db. A double 18" version with a 1000 watt peak amp ( as yours seems to be ) would add another 3db to that. So at best, a double 18" version would be capable of 134db peak with this amp. Keep in mind we still have no idea at what frequncy that peak SPL will be created.

We don't know what this speaker was designed for. Many are designed for use in horns, while other better suited for direct radiating designs. This one gives no real indication. So which design cabinet to put it in is a matter of punching in the Thiele Small parameters and trying different simulations. A horn should yield a few db more sensitivity, but I don't think it actually has that sensitivity at any real usable frequency.

Drawing on info from your other threads, it is apparent you haven't separated watts from SPL yet. In my humble opinion, You need a speaker capable of 136db peak to have real world output that is usable out to 50' from the source. The reason being is simply that you loose 16db of that to crest factor of the media and the fact you can't run peak wattage into the speaker for very long. A typical speaker capable of 136db peak is really only capable of around a 120db @ SPL 1m in real world usage. This doesn't factor losses for distance. So a double 18" version of what you have would just meet this criterion where many single 18" versions readily available are capable of 134db. I.E. you would have twice the speaker to get the same results as what is already out there in a single 18" design. 

You had mentioned building a wall of these things. Well you will certainly need a wall of these things to even keep up with a pair of single 18" units that are readily available. The issue is that you would be pulling the same rough number of watts from the wall ( if not more ) than the self powered single 18" units. Most modern active units are pulling 300-600 watts from the wall. So you can fit roughly 4 of them on a single 20 amp circuit. Most rack mounted amps with the same relative number of watts pulls roughly the same power. So you are are not really gaining anything there. Your speaker will use the same wall power for the same SPL output utilizing twice the space and twice the weight.

It comes down to sensitivity. This is the big make or break factor. Without knowing how truly sensitive the Rockville speaker is ( as in what frequency was that number created from ), I have no way of knowing how much noise it will really make. I think based on experience it's not going to get any louder than 132-134db peak and this is being generous. Real world output will be closer to 118db peak and you will be wanting of more. You will need 2 dual 18" units to do the same job as two single 18" units that you can get for roughly $1,000 each. While you could easily produce a dual 18" model for 1/3 that price, it will require much more work and may not actually ever sound as good as you desire.

The big thing is that you can't take a given design and stuff another speaker in it and expect to have the same performance. The sum of all parts is what makes it what it is. The speaker and the cabinet are designed to work with each other in a desirable way. I don't think any of us can say with any authority that the speaker you present will produce X results in any given design. All that means is that you have to do some RND and find out. This can be time consuming and expensive. So many variables come into place. The cabinet, the speaker and the DSP all have a say in how the speaker will work. The DSP is probably the biggest thing most don't understand. You can't fix every problem a speaker has with it, and even if it solves one issue, it can create another.

We advise against " Borrowing " designs and going off trying to create a brand new wheel for a multitude of reasons. The biggest reason is to save yourself from yourself. Stopping the insanity before it starts. The question you have to ask yourself is, are you a better engineer than the guys who actually design and make this stuff? They don't just grab random speakers off the shelf and create a cabinet that simply blows everyone away the first time every time. It is not by accident that JBL has a line of speakers that are affordable and sound good. They spent a lot of money and time developing a product to meet a goal. We care about your monetary well being and the impact your actions have on our industry. For every great sound guy there are 100 crappy ones. Not crappy for any other reason than they are naive, don't care to learn, simply don't care, or are negligent to the real reason for their employment. Much like an environmentalist, our job is to do no harm. Most of all, our job is much more than simply making things sound good. We are a service industry and when another guy leaves a bad taste in a clients mouth, it is that much harder for the next guy to bring and add value to what we do. We simply don't know enough about what you know, and what you have presented us isn't helping. If you have to ask, you probably don't know, so that means that you are embarking on a journey to make a brand new wheel. The wheel is already here. Save yourself the time and energy. Furthermore, save the space and the labor required to move what will ultimately be inferior to already available units. If you have to ask which is better, why one is more desirable and why you would take one design over the other, it tells us you don't understand why a speaker is even made to begin with. If you don't have a goal, all you have is a path that never ends. Stop dragging us and potential clients down that path with you. Given what I know about cabinet design, I know I can't beat what already exists. I don't care if I can get close for 1/3rd the cost, I make WAY more money just knowing I can't do it and utilizing the tools I have to increase demand for my services and continuing my research on how to best utilize those tools.
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Luke Geis

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Re: Gona try this another way
« Reply #4 on: May 15, 2018, 12:01:49 am »

After looking at the pre made cabinets they have to offer, you can only assume that the results they produce won't be much better than you could. Teh speaker you have of interest is 101db sensitivity and eve their best 4" model with a 200 watt peak is only 98db in the cabinet. That + or - 2db is their caveat to what frequncy in which it is sensitive to. So 101db at 240hz? Or is it 101db at 30hz? I can already tell you its nominally 98db at any given frequncy of interest. This means that the at best performance assuming peak wattage is 131db ( you will need a 2000 watt amp ) and for a pair of them each with 2000 watts you will only have 136db peak. This again assumes peak wattage. You can only power it with an amp that is roughly 1,500 watts, so now you are at 132.8db and well blow the 136db mark I mentioned before. You only have a 1000 watt amp so now you only get 131db. This puts your world output down to 115db at 1m. Not going to cut it......
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Scott Holtzman

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Re: Gona try this another way
« Reply #5 on: May 15, 2018, 12:02:01 am »

I would suggest you buy a pile of these. The pesky math is already done, and I don't think you could build the cabinets for that price. If you have spare drivers, that's a good thing.

Edited to add a word

What is someone going to pay you to show up with a pile of these?  That's the real question.  You owe to the folks coming to the show to do better than a $59.00 driver. 

Luke is correct and much more eloquent than I am.  A decent driver starts at about $300.  6 of these may on a good day possibly make as much noise on one frequency as the $300 driver.  They are going to heat up faster and burn up quicker.  You still have to have a pile of amps to drive them. 

No matter which way you spin it, it's wasted effort.
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Mike Spade

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Re: Gona try this another way
« Reply #6 on: May 15, 2018, 12:47:47 am »

Without a speaker designer software, it is at best a guess. It seems as if it will go down to 30hz. so it should be possible to create a box with it that gets relatively low. However, I don't believe some of its specs.

First it is a stamped steel frame. It claims 101db @ 1w 1M for sensitivity. Furthermore it claims sub 30hz capability with a 3" coil. These are not typical specs for a driver with teh price tag this one has. It states 1,200 watts as being its peak rating, and 600 watts is its RMS wattage. Usually the peak rating is 4x the RMS, but that is not relevant in this case really. Based on the specs you could only supply 600 watts total per speaker so a dual 18" cabinet would prefer to see about 1,200 watts. You only have 1000 watts as far as I can tell?

Given what it states, this speaker would only be capable of 128.8db at 1meter with 600 watts of power. Double that power to 1,200 watts and you only gain 3db for 131.8db. A double 18" version with a 1000 watt peak amp ( as yours seems to be ) would add another 3db to that. So at best, a double 18" version would be capable of 134db peak with this amp. Keep in mind we still have no idea at what frequncy that peak SPL will be created.

We don't know what this speaker was designed for. Many are designed for use in horns, while other better suited for direct radiating designs. This one gives no real indication. So which design cabinet to put it in is a matter of punching in the Thiele Small parameters and trying different simulations. A horn should yield a few db more sensitivity, but I don't think it actually has that sensitivity at any real usable frequency.

Drawing on info from your other threads, it is apparent you haven't separated watts from SPL yet. In my humble opinion, You need a speaker capable of 136db peak to have real world output that is usable out to 50' from the source. The reason being is simply that you loose 16db of that to crest factor of the media and the fact you can't run peak wattage into the speaker for very long. A typical speaker capable of 136db peak is really only capable of around a 120db @ SPL 1m in real world usage. This doesn't factor losses for distance. So a double 18" version of what you have would just meet this criterion where many single 18" versions readily available are capable of 134db. I.E. you would have twice the speaker to get the same results as what is already out there in a single 18" design. 

You had mentioned building a wall of these things. Well you will certainly need a wall of these things to even keep up with a pair of single 18" units that are readily available. The issue is that you would be pulling the same rough number of watts from the wall ( if not more ) than the self powered single 18" units. Most modern active units are pulling 300-600 watts from the wall. So you can fit roughly 4 of them on a single 20 amp circuit. Most rack mounted amps with the same relative number of watts pulls roughly the same power. So you are are not really gaining anything there. Your speaker will use the same wall power for the same SPL output utilizing twice the space and twice the weight.

It comes down to sensitivity. This is the big make or break factor. Without knowing how truly sensitive the Rockville speaker is ( as in what frequency was that number created from ), I have no way of knowing how much noise it will really make. I think based on experience it's not going to get any louder than 132-134db peak and this is being generous. Real world output will be closer to 118db peak and you will be wanting of more. You will need 2 dual 18" units to do the same job as two single 18" units that you can get for roughly $1,000 each. While you could easily produce a dual 18" model for 1/3 that price, it will require much more work and may not actually ever sound as good as you desire.

The big thing is that you can't take a given design and stuff another speaker in it and expect to have the same performance. The sum of all parts is what makes it what it is. The speaker and the cabinet are designed to work with each other in a desirable way. I don't think any of us can say with any authority that the speaker you present will produce X results in any given design. All that means is that you have to do some RND and find out. This can be time consuming and expensive. So many variables come into place. The cabinet, the speaker and the DSP all have a say in how the speaker will work. The DSP is probably the biggest thing most don't understand. You can't fix every problem a speaker has with it, and even if it solves one issue, it can create another.

We advise against " Borrowing " designs and going off trying to create a brand new wheel for a multitude of reasons. The biggest reason is to save yourself from yourself. Stopping the insanity before it starts. The question you have to ask yourself is, are you a better engineer than the guys who actually design and make this stuff? They don't just grab random speakers off the shelf and create a cabinet that simply blows everyone away the first time every time. It is not by accident that JBL has a line of speakers that are affordable and sound good. They spent a lot of money and time developing a product to meet a goal. We care about your monetary well being and the impact your actions have on our industry. For every great sound guy there are 100 crappy ones. Not crappy for any other reason than they are naive, don't care to learn, simply don't care, or are negligent to the real reason for their employment. Much like an environmentalist, our job is to do no harm. Most of all, our job is much more than simply making things sound good. We are a service industry and when another guy leaves a bad taste in a clients mouth, it is that much harder for the next guy to bring and add value to what we do. We simply don't know enough about what you know, and what you have presented us isn't helping. If you have to ask, you probably don't know, so that means that you are embarking on a journey to make a brand new wheel. The wheel is already here. Save yourself the time and energy. Furthermore, save the space and the labor required to move what will ultimately be inferior to already available units. If you have to ask which is better, why one is more desirable and why you would take one design over the other, it tells us you don't understand why a speaker is even made to begin with. If you don't have a goal, all you have is a path that never ends. Stop dragging us and potential clients down that path with you. Given what I know about cabinet design, I know I can't beat what already exists. I don't care if I can get close for 1/3rd the cost, I make WAY more money just knowing I can't do it and utilizing the tools I have to increase demand for my services and continuing my research on how to best utilize those tools.

"Without a speaker designer software, it is at best a guess. "

I never said nobody could use software, in fact, I'm trying to talk to someone who may have enough experience with the software to be able to look at the ts specs and tell me if they see anything that may suggest what type of cab it may be used for.

Yakno like in winisd when it gives you a suggestion based upon the ts?

I'd love to crunch some numbers on this tbh in winisd!

"You only have 1000 watts as far as I can tell?"
Technically giving them 980w rms verse 2, this is not peak.

"We don't know what this speaker was designed for. Many are designed for use in horns, while other better suited for direct radiating designs"

Thats why I'm posting here since the only real thing I know to look at is the qts that winisd looks at and I figured someone here may know more by looking at the numbers like others have on other forums.

"The big thing is that you can't take a given design and stuff another speaker in it and expect to have the same performance."

Totally agree, this is why I'm looking at different cases and taking ideas from proven working cases to then take into winisd to recalculate the volume, port size/how long/how many.

I mean theres people who make custom boxes for trucks and cars all the time with any driver you throw at them by just doing some simple calculations and running winisd, theres no reason why I couldnt do the same thing with these.

I mean to say this another way, you say 2 grand for two good self powered 18s. The way I look at it is mdf is like 30-40 a sheet so for even a grand (half that) I could make alooot of different cases and try different things. I mean I already own the drivers and have the power, the investment here is purely time and wood. I don't need to reinvent the wheel, obviously I'd be using a already proven style like a front loaded bass reflex cab, something like a gsub seems to be the best idea so far. I have them currently in a yorkville sw1000 double 18 and they sound great in that case, good enough that I'm here thinking about designing a cab for them.

"I don't care if I can get close for 1/3rd the cost, I make WAY more money just knowing I can't do it and utilizing the tools I have to increase demand for my services"

I don't make money renting my equipment. This is a hobby gone wildly out of control to the point where I now have land and do monthly events on said land. So I mean cost matters to me, I don't have 2 grand laying around for 2 speakers and have a extremely hard time justifying that price when you can find even used cabs for less. Again I'm a woodworker so making a case instead of buying one sounds way better to me when I'm seeing alot of things made out of cheap mdf instead of birch, I mean mdf is great if your keeping it at home or a install or a test cab but for outdoor I want birch.
« Last Edit: May 15, 2018, 07:44:19 am by Mike Spade »
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Mike Spade

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Re: Gona try this another way
« Reply #7 on: May 15, 2018, 12:54:42 am »

What is someone going to pay you to show up with a pile of these?  That's the real question.  You owe to the folks coming to the show to do better than a $59.00 driver. 

Luke is correct and much more eloquent than I am.  A decent driver starts at about $300.  6 of these may on a good day possibly make as much noise on one frequency as the $300 driver.  They are going to heat up faster and burn up quicker.  You still have to have a pile of amps to drive them. 

No matter which way you spin it, it's wasted effort.

Who said anyone is paying me to show up with these?

I have land and throw my own monthly events on said outdoor land, these are used nearly exclusively for that.

"You owe to the folks coming to the show to do better than a $59.00 driver. "

So the price is what makes it trash? So your saying the 500w 18 I have in the orginal yorkville sw1000 that would cost me $450 is better then the $60 driver purely cuz of the price? Despite both playing around the same volume in the same cases with the same wattage? I mean if you ask me I think the $60 drivers sound better then the $450 drivers and thats why I never bought another pair of the $450 ones, these $60 ones where supposed to be "temp" drivers till I saved up for the $450 ones but now I'm not even gona bother cuz theres no point.

Just cuz they can con you into paying a high price doesn't always mean what your getting is somehow instantly better. Sure some drivers like 18sounds are worth the high price tag, but can I afford that? No. So its not a option.

"6 of these may on a good day possibly make as much noise on one frequency as the $300 driver.  They are going to heat up faster and burn up quicker. "

2 of them going giving 980w rms for over a year used monthly, playing EDM straight for 12 to 36 hours. I think they handle the heat and power just fine from my experience, but maybe you need a longer test then 36 hours of continuous play at max volume? (just under amp clip, limited by a dbx 266 to stay there)

"No matter which way you spin it, it's wasted effort."

Is it really? These subs are as good or better then the yorkville 18s I replaced them with, that is a saving of $750 when I got a pair of rockvilles for $150 shipped to me, otherwise I would've been spending $900 for driver replacements that would've been no better then the drivers I got for $150.
« Last Edit: May 15, 2018, 12:59:36 am by Mike Spade »
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Mike Spade

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Re: Gona try this another way
« Reply #8 on: May 15, 2018, 01:05:38 am »

After looking at the pre made cabinets they have to offer, you can only assume that the results they produce won't be much better than you could. Teh speaker you have of interest is 101db sensitivity and eve their best 4" model with a 200 watt peak is only 98db in the cabinet. That + or - 2db is their caveat to what frequncy in which it is sensitive to. So 101db at 240hz? Or is it 101db at 30hz? I can already tell you its nominally 98db at any given frequncy of interest. This means that the at best performance assuming peak wattage is 131db ( you will need a 2000 watt amp ) and for a pair of them each with 2000 watts you will only have 136db peak. This again assumes peak wattage. You can only power it with an amp that is roughly 1,500 watts, so now you are at 132.8db and well blow the 136db mark I mentioned before. You only have a 1000 watt amp so now you only get 131db. This puts your world output down to 115db at 1m. Not going to cut it......

"After looking at the pre made cabinets they have to offer, you can only assume that the results they produce won't be much better than you could."

Yeah maybe your right, but the difference is I'd be making double 18s instead of single 18s and they would be made in birch instead of mdf, I could also tune them differently and add more volume so I honestly do think I could produce better results when from what I can see these rvp drivers are better then the ones they used in those cabs.

Again those cabs are NOT using the same drivers as the rvp 18s I have, those are 500w 18s, these are 600w 18s, both have different ts specs.

I see no point in buying one of those cabs+speakers if I already have the speakers+amp and just need the cab, so far gsub seems to be what I'm leaning towards with a 30hz tune, I won't know proper volume or exact measuments till I finish crunching numbers in winisd

I mean again a sheet of mdf is like 30-40, a test cab would cost me some work and thats about it.. but if I bought one of those pre made subs and didnt like it I'd be stuck with it and out a decent shipping cost even if they did let me return it. (around $80-90 shipping for me to get one in canada so thats a good chunk of the total value)
« Last Edit: May 15, 2018, 07:45:15 am by Mike Spade »
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Scott Holtzman

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Re: Gona try this another way
« Reply #9 on: May 15, 2018, 01:41:45 am »

Car stereo speakers load into the car and play in the near field.  Not a valid comparison.

The Yorkville driver is cast and has a different suspension, voice coil and cooling design. 

I find it hard to believe that driver takes full power for 36 hours but if you say so I am not going to dispute it.

You can only do so much with 20 dollars in manufacturing budget.  That is about all you have it a $60  driver.

Some basic ideas.  Front loaded cabinets have no gain and to get loud or low they need power and excursion.  Notice I said loud or low you can have one or the other with a front loaded cabinet, low efficiency drivers and relatively low power. 

Now horns can create acoustic gain.  It comes at a price however.  Designing horns is tricky business.   

Of you Google the terms in the speaker specs you can translate them to the WinISD equivalent.



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