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Old Feb 21, 2013, 03:22 PM
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Eddie P's Avatar
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Originally Posted by DavidHarrison View Post
I have a follow-up question for everyone relating to my previous post. Would anyone be interested in us getting in this Monacor SPH-30X/4SW speaker?
David I looked at that speaker. While I'm not sure if I myself am interested in specifically this speaker due to the price, the question brings up something I have pondered in the past but still have questions regarding the full implications. I would certainly be interested in smaller speakers of this size in a lower price bracket though.

The question for me is, can there be a solution that uses two to four smaller speakers that are not necessarily as loud but can be positioned better for more equal sound projection at a variety of aircraft attitudes based on the remote position of the pilot and observers. (This may be what you are talking about in regard to these 3" speakers in fact!)

For my current project, I know my 4" speaker set is the best solution for a loud system. I should have some great sound on the ground and a close fly by at low level After all, the speaker points down, so on the ground, the reflected sound will be easy to hear. On just about any fly by, the reflected sound and such will still reach us well. But in flight, I expect the speaker will be muffled or even inaudible in attitudes where the top of the model plan form is viable such as in a large loop or inverted flight from above and at a certain distance away. In most cases the model sounds will be "hear-able" but there are several times I'm sure it just won't be very clear what the noise coming from the model is except some airframe, propeller, some speakers sounds and speed controller noise.

Now if I had four smaller speakers installed in my current "mid size" model in well planned locations, the advantage could be many. If I had a large enough model the 4" speakers would be great but most of my models are in the 65 - 100 inch wing span regime - 2 speakers in the lager models and one in the smaller ones. But, I could have lighter speakers and more evenly distribute the load around the airframe with 4 small and light speakers (like a setup of 2" to 3" speakers), and each speaker could be hidden / camouflaged better. Also I could have speakers that could be heard in just about any attitude. While the total sound in ideal locations may not be as loud, I'd expect the overall "ups and downs" of audible sounds may in fact be more consistent throughout a large variety of aircraft maneuvering and give the impression of realism in a variety of aircraft attitudes. This is just my thinking, and I do not claim to have nearly as much of an insight as many of you guys here as I really have only been dabbling with this sound stuff for the last season.

For those reasons I'm still really interested in what sort of speakers that may be recommend us to try if we wanted to try two to four smaller speakers.

The advantages of David's sound board are many on setup. I still think we have a very powerful setup menu and what we can do with these boards as far as customization and versatility are incredible and I'd love to have the chance to use a larger variety of speakers but I am really out of my league when it comes to speakers.
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Old Feb 21, 2013, 03:54 PM
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Canada, ON, Ottawa
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Originally Posted by Eddie P View Post
David I looked at that speaker. While I'm not sure if I myself am interested in specifically this speaker due to the price, the question brings up something I have pondered in the past but still have questions regarding the full implications. I would certainly be interested in smaller speakers of this size in a lower price bracket though.

The question for me is, can there be a solution that uses two to four smaller speakers that are not necessarily as loud but can be positioned better for more equal sound projection at a variety of aircraft attitudes based on the remote position of the pilot and observers. (This may be what you are talking about in regard to these 3" speakers in fact!)

For my current project, I know my 4" speaker set is the best solution for a loud system. I should have some great sound on the ground and a close fly by at low level After all, the speaker points down, so on the ground, the reflected sound will be easy to hear. On just about any fly by, the reflected sound and such will still reach us well. But in flight, I expect the speaker will be muffled or even inaudible in attitudes where the top of the model plan form is viable such as in a large loop or inverted flight from above and at a certain distance away. In most cases the model sounds will be "hear-able" but there are several times I'm sure it just won't be very clear what the noise coming from the model is except some airframe, propeller, some speakers sounds and speed controller noise.

Now if I had four smaller speakers installed in my current "mid size" model in well planned locations, the advantage could be many. If I had a large enough model the 4" speakers would be great but most of my models are in the 65 - 100 inch wing span regime - 2 speakers in the lager models and one in the smaller ones. But, I could have lighter speakers and more evenly distribute the load around the airframe with 4 small and light speakers (like a setup of 2" to 3" speakers), and each speaker could be hidden / camouflaged better. Also I could have speakers that could be heard in just about any attitude. While the total sound in ideal locations may not be as loud, I'd expect the overall "ups and downs" of audible sounds may in fact be more consistent throughout a large variety of aircraft maneuvering and give the impression of realism in a variety of aircraft attitudes. This is just my thinking, and I do not claim to have nearly as much of an insight as many of you guys here as I really have only been dabbling with this sound stuff for the last season.

For those reasons I'm still really interested in what sort of speakers that may be recommend us to try if we wanted to try two to four smaller speakers.

The advantages of David's sound board are many on setup. I still think we have a very powerful setup menu and what we can do with these boards as far as customization and versatility are incredible and I'd love to have the chance to use a larger variety of speakers but I am really out of my league when it comes to speakers.
Eddie, in general, smaller speakers have two disadvantages - much lower power handling capacity and lower sensitivity. But if you are willing to have a quieter sound system they could be used.

We do sell and stock 2.5inch Visaton 8Ohm speakers that can handle 8 Watts and are reasonably priced at CAD$19.95 each. They are a bit heavier than the 4 inchers at 207 grams (7.3oz). So if you used four of these in a series/parallel arrangement they could probably be used with the ShockWave sound module. Their sensitivity is 84dB/1W/1m so would definitely be quieter than the 4 inchers.
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Old Feb 21, 2013, 11:48 PM
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So the 4" speakers are 90dB/1W/1m and weigh 5.7 ounces...

The 2.5" speakers are 84dB/1W/1m and weigh 7.3 ounces.

How much of a difference is 84db vs 90db in reality? I suppose one would have to hear it in a model to really know. The other question is how much do most people really push their speakers to the limit rating anyway... In other words if running a 4" speaker on a 4s setup is not getting it close to the maximum output, then maybe it's a mute point. However, I am concerned about the weight of the 2.5" speakers. There have to be 2.5" class speakers that are lighter, right? Quality may be a question but I'm just free thinking here.

A question I ponder would be if a lighter, smaller set of 2.5" class speakers mounted in a greater variety of locations and directionally and strategically mounted - could that in many ways make up for and be superior in a variety of conditions to an alternative arrangement featuring fewer speakers having the advantage of specific loudness but only in one or two directions?
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Old Feb 21, 2013, 11:52 PM
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Originally Posted by Fan369rc View Post
David,

I agree with others....it's nice to see this forum start up! It's great seeing other projects and seeing how each unique setup is tackled. Thank you for your assistance thus far with my SFX6 module...I hope to have the Camel flying this spring. Here is a link to the RC Groups video gallery, and some photos of the initial installation.

http://static.rcgroups.net/forums/at...pwith%20Camel%
I'm super curious about the clear plastic cylinder. What is the purpose of it, and can you explain your setup a little more? (post 23, page 2 of this thread) Looks like very nice workmanship. Thanks for posting it.

http://www.rcgroups.com/forums/showp...3&postcount=23
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Old Feb 22, 2013, 10:27 AM
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Originally Posted by Eddie P View Post
How much of a difference is 84db vs 90db in reality?

There have to be 2.5" class speakers that are lighter, right?
Eddie, the difference is 6dB which is 4 times less power and 4 times less SPL. This doesn't mean it is heard as four times less loud though. A general rule of thumb is that the human ear can just about perceive a 1dB change in SPL level. 3dB is quiet a bit noticeable and 6dB is very much noticeable. Another rule of thumb is that for a sound to be perceived as "twice as loud", the SPL has to be 10dB more which is 10 times!!

Yes there are smaller, lighter, speakers e.g. the Visaton BF45 which Thomas Benedini sells. It is 2", can handle 4Watts, weighs only 32 grams, or 1.2oz BUT has a sensitivity of only 79dB/1W/1m. This is a huge difference from the 90dB of the R10S speakers. Now by all means try an array of these speakers - we can order them in from our distributors as a special order for you if you like. Perhaps make a long test box about the same size as your fuselage out of plywood and distribute the speakers around it and just try it out for loudness.

If anyone is wondering why I constantly refer to Visaton speakers - yes there are many speaker manufacturers out there but :

1) We have established a good business relationship with Visaton's Canadian distributor and have a credit account with them.

2) We have been in this business for about 7 years now and continually search for better speakers - defining "better" as smaller, lighter, more sensitive, can handle more output power and/or cost less. The results of these searches always come down in favour of the Visaton series as being able to provide the best all-round compromise between these and other conflicting requirements.

3) We even enlisted the help of the sales engineers at our loudspeaker distributor since they carry many different brands and they couldn't come up with another brand that suits our needs better either.

4) Thomas Benedini in Germany also uses Visaton speakers and a few years ago I discussed speaker choices with him and we both came to the same conclusion that, in general, the Visaton range was the best for the job, given all those conflicting requirements.

Regards,
David
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Last edited by DavidHarrison; Feb 22, 2013 at 10:39 AM.
Old Feb 22, 2013, 10:43 AM
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Nice website David,
Very good idea here with this thread. Wouldn't it be nice if speaker manufacturers stamped out speaker frames in aluminum instead of steel? Would be good in outdoor marine applications for corrosion and all types of models that go outdoors. Some weight savings also. The magnets could still be riveted in place.
**Neons** Bob
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Old Feb 22, 2013, 10:58 AM
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Originally Posted by **neons** View Post
Nice website David,
Very good idea here with this thread. Wouldn't it be nice if speaker manufacturers stamped out speaker frames in aluminum instead of steel? Would be good in outdoor marine applications for corrosion and all types of models that go outdoors. Some weight savings also. The magnets could still be riveted in place.
**Neons** Bob
Hi, neons. I don't know of any speaker manufacturer who uses aluminum frames so there must be a good reason why. I suspect it is because the frames have to be very rigid to precisely hold the voice coil in the centre of the magnet gap, so maybe an aluminum frame would have to be thicker and possibly costlier, but I am only guessing here.
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Old Feb 22, 2013, 12:25 PM
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I have been wanting to add some sound 'boxes' to my speakers for a while. (basically since I installed them)
I have done some minor research on the methods people use and discounted most as practical due to the location of my speakers and available access point. (a door in the side of the plane ~ 2" x 4")
I have recently decided to cut into the fuse and change the way they are mounted. This provides the opportunity to box them and enhance my sound.

What I would like to do is the 'pvc pipe method'. Assuming people reading this know what I am talking about, has anyone already done the math on the best thickness pipe and how long it should be for each speaker using this system?
My setup is the standard shockwave pcb running on 6s w/2 4" Visatons as provided by MSI.
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Old Feb 22, 2013, 12:33 PM
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Originally Posted by Arkole Blake View Post
I have been wanting to add some sound 'boxes' to my speakers for a while. (basically since I installed them)
I have done some minor research on the methods people use and discounted most as practical due to the location of my speakers and available access point. (a door in the side of the plane ~ 2" x 4")
I have recently decided to cut into the fuse and change the way they are mounted. This provides the opportunity to box them and enhance my sound.

What I would like to do is the 'pvc pipe method'. Assuming people reading this know what I am talking about, has anyone already done the math on the best thickness pipe and how long it should be for each speaker using this system?
My setup is the standard shockwave pcb running on 6s w/2 4" Visatons as provided by MSI.
Arkole, designing ported loudspeakers is truly a science in itself. I doubt many aeromodellers would have the scentific knowledge in acoustics and speaker design to "do the math" as you ask. I think you'll find that in practice it is all done by experiment, rather than "math" as such.
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Old Feb 22, 2013, 01:43 PM
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Originally Posted by DavidHarrison View Post
...Visaton BF45 ... It is 2", can handle 4Watts, weighs only 32 grams, or 1.2oz BUT has a sensitivity of only 79dB/1W/1m.
David
Hi David, sent you a PM, thanks for the information - it's very helpful.
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Old Feb 22, 2013, 02:06 PM
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Sound Enclosures

In response to Eddie P on post #34, the plastic cylinder (part of a beef jerky maker from Walmart...though I don't make beef jerky) is used to add additional volume to the sound box surrounding the engine.

Your Corsair installation looks awesome....I hope we can hear and see it fly in a future video!

The goal for the Sopwith was to use a heavy speaker to replace the 16 oz lead ballast that came with plane, along with providing a maximum RMS speaker value for the SFX6 soundcard. It's using a 3S battery along with one 4 ohm speaker...which is acceptable per David.

I would love to try Monacor SPH speakers in a project...but the price has held me back.

I apologize for the bad video link posted previously....I hope that this one works.

http://www.rcgroups.com/forums/showthread.php?t=1836745

As the thread is currently talking about sound boxes, attached are a few photos from a Hangar 9 Fokker setup. For me, as a newbie, I just figured to make any enclosures as large as the available space would allow. Many thanks to all those that have posted similar projects and past experiences with speakers on other threads and sites (Wattflyer, RC Universe, etc.)
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Old Feb 22, 2013, 02:29 PM
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Hi, all. Since we are currently talking about small speakers, I thought I'd put up a few things that determine speaker performance.

1) Loudspeaker efficiency - i.e. (power out / power in) is only about 1%.
That means if you put in 40Watts of electrical input power you only get
0.4Watts of sound power output. The remaining 39.6Watts gets
dissipated as heat!!

2) This heat has to be dissipated somehow. The primary heatsink of a speaker
is its magnet. Therefore in order to handle high power you have to have a
large heavy magnet. This is why small speakers can't take much power.

3) The amount of "Power" in a sound wave depends not only on its pressure
(SPL) but also on the rate of change of that pressure i.e. its frequency.
So for a given speaker cone displacement, the lower the frequency, the
quieter the sound. This is made up for in woofers my moving a larger
quantity of air.

4) This is why woofers have a very large cone and tweeters have a very
small cone to get the same amount of sound "power" out.

So not only do small speakers have a low power handling capacity, but they also have a very poor low frequency response. For some planes e.g. jets with a high proportion of H.F. sound that is OK, but not for a large radial piston engine which has a large amount of L.F. energy.
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Old Feb 22, 2013, 02:36 PM
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...wrong plane....

Eddie P....not a Corsair, sorry.....(I still must have the newer Parkzone Corsair on my mind....those electric retracts keep inviting me to buy....)
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Old Feb 22, 2013, 03:41 PM
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Model Sounds aircraft

David,

I recall reading in one of your newsletters or somewhere previously on your site that you were working on an aircraft to help showcase your product(s).....that you could take to shows, fly-ins, etc. Was it a P-51?

If so, is that complete, or a work in progress? It would be great to see it....or even see a build thread on it...possibly in this thread?
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Old Feb 22, 2013, 03:49 PM
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Originally Posted by Fan369rc View Post
David,

I recall reading in one of your newsletters or somewhere previously on your site that you were working on an aircraft to help showcase your product(s).....that you could take to shows, fly-ins, etc. Was it a P-51?

If so, is that complete, or a work in progress? It would be great to see it....or even see a build thread on it...possibly in this thread?
Yes, we're still working on it and it is a long term project. It is a Top-Flite 1/5 scale P51D Mustang in the "Big Beautiful Doll" colours. I have already started a build thread in RCScaleBuilder.com -> http://www.rcscalebuilder.com/forum/...TID=19024&PN=1
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