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Author Topic: 2 speakers  (Read 2792 times)

Ryanb

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2 speakers
« on: February 23, 2013, 10:48:38 PM »

This maybe a stupid question but would 2 speakers be louder than 1 from the same amp?



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malcolmfrary

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Re: 2 speakers
« Reply #1 on: February 24, 2013, 10:09:57 AM »

This maybe a stupid question but would 2 speakers be louder than 1 from the same amp?
No.
Unless either
a) the one speaker couldn't handle the power from the amp
b) you turn the wick further up on the amp 
c) the 1st speaker was sited so you couldn't hear it.
The amp gives just so much power, the speaker converts that to sound to the best of its ability.  It doesn't matter whether its one speaker or a dozen, you only have so much energy available to distribute.
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essex2visuvesi

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Re: 2 speakers
« Reply #2 on: February 24, 2013, 11:14:39 AM »

2 speakers may give a more "richer" sound however
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Ryanb

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Re: 2 speakers
« Reply #3 on: February 24, 2013, 11:44:53 AM »

I am trying to think of a way to make the sounds louder as the speaker is in the hull, however, after a sleepless night I have decided to reposition the speaker.

I didn't think another one would make a difference!
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F4TCT

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Re: 2 speakers
« Reply #4 on: February 24, 2013, 12:19:25 PM »

Theres something on the market where you plug it into an mp3 player or whatever and attach it to something like an empty mcdonalds cup or bucket or something concave etc (inside of superstructure) and it converts that item into a speaker with good results and quite loud.


was thinking of possibly looking into it for a future build.
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Circlip

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Re: 2 speakers
« Reply #5 on: February 24, 2013, 12:29:48 PM »

Pringles keep doing a freebie speaker using a Pringles tube as a housing. Speaker is a self contained unit powered by a 1 1/2V internal mini pencell.
 
  Regards  Ian.
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inertia

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Re: 2 speakers
« Reply #6 on: February 24, 2013, 12:49:15 PM »

 Imagine turning on your TV in the lounge, then leaving the room and closing the door behind you. Why do you suppose that the TV doesn't sound very loud?
 Common sense tells you that it's BECAUSE THE SOUND CAN'T GET THROUGH A CLOSED DOOR. Open the door again and it gets louder. Speakers in model boats follow pretty much the same rules.
  • The air from the front of the speaker cone needs the shortest and most direct, unobstructed path to escape from the hull. Putting it under the deck with no ventilation is a waste of time and power. Some folk make a tube which fits around the cone and allows the sound straight up to a funnel or deck grating - perfect.
  • The speaker needs to be mounted onto a flat board with a hole in it (for the cone) which in turn is fastened firmly to the hull or superstructure - or forms part of it. This is called a baffle board and will transmit the vibrations from the speaker into the hull, thus using it as a resonator (like a violin body).
  • You need to site the speaker so that the air from the front of the cone can't "mix" with the air from the back e.g. put a box around the back of the speaker or a tube around the front. If the two sets of airwaves do get to mix then they will cancel each other out and you'll hear very little.
Sound engineer Steve Dean wrote a very good article about speakers in MMI a few months back - look it out and have a good read.
 To answer your specific  question about using two speakers, see Malcolm's reply - I can add nothing to that.
DM

 
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Circlip

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Re: 2 speakers
« Reply #7 on: February 24, 2013, 12:53:17 PM »

Quote
You need to site the speaker so that the air from the front of the cone can't "mix" with the air from the back

  Not necessarily Glasshopper  %)
 
  Regards  Ian
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Bob K

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Re: 2 speakers
« Reply #8 on: February 24, 2013, 01:51:40 PM »

This takes me back to when many of us built our own Hi Fiís, and constructed speaker enclosures.  Anyone remember the mag' Practical Wireless?.  We went to great lengths to mount speakers with an airtight seal, behind which was a labyrinth to ensure air took a long path and exited so that it was not in phase with air from the front.

Most model boat systems seem to mount the cone in free air with only a 2 cm grill to exit from.  Take the deck off and itís instantly louder.  Mount the speaker in a large box and it's better still.

DM is quite correct.
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Re: 2 speakers
« Reply #9 on: February 24, 2013, 01:56:32 PM »

No one has mentioned impedance matching when changing or adding speakers.

Ned
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dreadnought72

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Re: 2 speakers
« Reply #10 on: February 24, 2013, 02:11:23 PM »

...Or, indeed, wiring two (or more) speakers in phase.

Andy
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Bob K

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Re: 2 speakers
« Reply #11 on: February 24, 2013, 02:44:59 PM »

...Or, indeed, wiring two (or more) speakers in phase.
Andy

If impedance was merely DC resistance then wiring two 8 ohm speakers in series and the amp would 'see' 16 ohms.  Wire them in parallel, it could 'see' 4 ohms under load.  However it doen't work quite like that.  Most multi speaker enclosures usually have additional circuitry to balance the impedance.
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inertia

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Re: 2 speakers
« Reply #12 on: February 24, 2013, 05:18:36 PM »

Let's not lose sight of the fact that we are discussing engine sound systems in model boats - not music-quality HiFi systems in lounges.
If you're after high-quality, high-volume sound at the sort of distances we are dealing with then yes, it's quite possible, as long as you have a very large model and an even larger budget..................and you follow the basic laws of physics when designing and installing the speakers.
Most folk aren't that keen - or that rich!
DM
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Circlip

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Re: 2 speakers
« Reply #13 on: February 24, 2013, 05:36:43 PM »

Persisely, only full size boat that makes a racket at any distance is the one that travels between Los Christianos and La Gomera, one of Fred's ferries.
 
  Regards  Ian
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midships

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Re: 2 speakers
« Reply #14 on: November 02, 2013, 07:36:22 PM »

hi all has any one used the master blaster from cornwall models with the twin cat sound which i belive are the engines used in the tamar life boats ,thought about action electronics p100 but these appeer to be quite expensive ,also would it be fesible to use a micro servo motor for the radar or would i be better puchasing a motor made for this purpose
i am glad there is so much help avalibe  for us not so clever modelers
regards
n
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malcolmfrary

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Re: 2 speakers
« Reply #15 on: November 02, 2013, 08:21:24 PM »

For the most part, you get pay for what you get, and with a bit of luck, you get what you pay for.  If you care to do your own design and development you can undercut the "noisy thing" cost and arrive at the same functionality.  Maybe.
If the servo chosen can be modified for continuous rotation (Does it have a full set of teeth on the output gear?  Are you happy with removing the electronics and hooking the motor direct to a battery?) the motor and its gearbox will do a fine job of driving a radar provided you find somewhere for it to live.  Same applies to purpose built mini geared motors.
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Steve Dean

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Re: 2 speakers
« Reply #16 on: November 03, 2013, 10:16:32 AM »

Hi all. The subject of speakers in models seems the be a regular topic. As INERTIA stated I wrote an article on this very subject in MMI some months ago. I'll be bold and make an offer Ö.. if any of you are going to the International Model Boat show and you want some guidance on this subject I will be at the pool for the duration of the show (I'm the Pool Master and I also provide the PA system) and would be happy to help you and demo the systems in my models.


On the subject of using a servo to drive a radar scanner. Firstly, let me state that there are a number of motors available for this purpose. Robbe and Model Motors Direct offer them. If memory serves me correct I also believe that Action used to offer one. Dave will be at the show on the Component Shop stand so go and see him. Modifying a servo is fairly easy if you are confident in doing this BUT of course it will void the warranty. You need to take the servo apart and remove the feedback potentiometer without breaking the three wires. You then glue the pot to the outside of the servo case and will need to cut a slot for the wires to exit the case. You then need to remove the end stops on the gear that limits the servo travel. When you put the servo back together it will probably run continuously in one direction. If you turn the pot you can find the null point at which it stops rotating. You can then adjust the pot to make it run in the direction you want. IF THIS SOUNDS TOO COMPLICATED FOR YOU - THEN DON'T DO IT.


Again if you want some guidance then come and talk to me. I'll show how I use this technique to make a seagull rotate via radio control.


Cheers
Steve Dean
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inertia

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Re: 2 speakers
« Reply #17 on: November 03, 2013, 01:37:15 PM »

I'll show how I use this technique to make a seagull rotate via radio control.
Cheers
Steve Dean
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DM
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Steve Dean

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Re: 2 speakers
« Reply #18 on: November 06, 2013, 02:15:40 PM »

Dave, if you think my rotating seagull is weird Ö.. just wait till you see my Alien in his rocket ship. Loads of LED lighting effects and surprise, surprise, lots of 'out of this world' sound effects coming from a 'Noisy Thing' on steroids. And if you get in it's way it squirts green plasma at you. Am I just sad or what !!!!


See ya at the show.
Steve
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