Model Boat Mayhem - Forum

Technical, Techniques, Hints, and Tips => The "Black Arts!" ( Electrics & Electronics ) => Topic started by: Chuffy on October 29, 2007, 05:19:05 PM

Title: Speaker for sound simulator.
Post by: Chuffy on October 29, 2007, 05:19:05 PM
Hi all, can anybody point me in the right direction to get a 100mm speaker for a JJC module, It should be 8 omhs and 30 watt. Any help would be welcome, or what speaker do you use?

Paul.
Title: Re: Speaker for sound simulator.
Post by: Martin [Admin] on October 29, 2007, 05:24:57 PM
I think an ordinary speaker from Maplins should do just paint it with a varnish of somesort to water proof it.

www.maplins.co.uk
Title: Re: Speaker for sound simulator.
Post by: Colin Bishop on October 29, 2007, 05:39:10 PM
If you can get a Mylar one it will be weatherproof see: http://www.maplin.co.uk/Search.aspx?criteria=mylar%20speaker&source=15&SD=Y

These go up to 87mm but only quote 10w. I used one in my old 1:1 boat as a cockpit speaker and it was certainly loud enough.
Title: Re: Speaker for sound simulator.
Post by: malcolmfrary on October 29, 2007, 05:41:04 PM
Maplin also do a range of mylar speakers - already water resistant, but may not be large enough.  One important thing to watch is that the rated resistance does not go below 8ohms.  Power rating for intermittent sounds is relatively unimportant - a speaker capable of surviving a 10 watt continuous load will do the job and weigh nothing like as much.  Another important point is to mount the speaker so that it is on a baffle to make sure the sound coming off the back has a long way to go before it starts to cancel the sound off the front.
Hi Colin.  Snap!
Title: Re: Speaker for sound simulator.
Post by: 2772e on October 29, 2007, 07:21:19 PM
I use old mobile phone car kit speakers, come on a bracket and are enclosed.

Works for me!

Regards

Simon
Title: Re: Speaker for sound simulator.
Post by: Chuffy on October 29, 2007, 08:55:19 PM
Many thanks to you all, I'm off to Maplins tomorrow!
Title: Re: Speaker for sound simulator.
Post by: ABRAD on November 04, 2007, 11:37:56 PM
Action electonics for mylar speakers as well
Title: Re: Speaker for sound simulator.
Post by: FullLeatherJacket on November 04, 2007, 11:52:24 PM
30W??!! The Beatles' VOX amps were only 30 Watts, and they could fill a cinema or theatre with those. Our 100mm mylar-cone speaker is 10W.
You could try Farnells for one.
FLJ
Title: Re: Speaker for sound simulator.
Post by: wombat on November 06, 2007, 07:07:01 PM
30Watt output on the amp doesn't mean you need a 30W speaker - you can use less as long as you back off the volume. 30W into a small speaker will be bl***y loud!!! We used 3*30W speakers for the PA on a container crane. 10 to 16W should be more than adequate for a sound system on a boat unless you want to hear it from the other side of the lake.

Wom
Title: Re: Speaker for sound simulator.
Post by: Chuffy on November 07, 2007, 10:05:59 AM
Hi all,

 Re the wattage of the speakers for my Severn, I took the details straight from JJC's web site , he recommended 30 watt 8 ohms
for a turbocat. I could'nt get speakers of the size that I wanted at Maplins so I'll go and talk to Phil Locke at Warwick at the weekend.

Cheers.
Title: Re: Speaker for sound simulator.
Post by: DickyD on November 07, 2007, 10:18:39 AM
Hi Chuffy
Got my speakers for JJC unit from Maplins on internet. About 5 each
Title: Re: Speaker for sound simulator.
Post by: Circlip on November 07, 2007, 10:27:46 AM

    Perhaps JJC is covering his posterior in going for a 30W rating, what about transients and spikes? I have seen high
     power HI-FI speakers blown out by cheap low power amplifiers, no reflection on JJC circuitry, but ultimately the
     voice coil makes a pretty good fuse.
Title: Re: Speaker for sound simulator.
Post by: Stavros on November 07, 2007, 03:25:09 PM
yes but just to throw a spanner in the works is it 30watt RMS or 30Watt Peak power heck of a difference in both ratings

Stavros
Title: Re: Speaker for sound simulator.
Post by: Circlip on November 08, 2007, 03:33:47 PM

  Speaker specs are USUALLY rated as PEAK HANDELING POWER,        AMPLIFIER ratings are RMS or PEAK.
Title: Re: Speaker for sound simulator.
Post by: malcolmfrary on November 08, 2007, 10:29:31 PM
Manufacturers of amps usually like to quote really big numbers.  If they quote instantaneous peak power, divide by four for a realistic RMS value.  If an amp is working off 12 volts into 8 ohms, it is unlikely that the speaker will ever see more than 10watts, and if the amplifier LS connections are a LS line and the other side to ground, then about 5 watts is even more likely.  As a handy way of muddying the issue, some speakers are intended for use in HiFi situations with more than one drive unit per box - and they get quoted as "siutable for use in system up to n watts".
As said before, get one about the size you want, mount it so that the noise coming off the back does not cancel the noise coming off the front, and if you can stand the weight, get the one with the knobbliest magnet.
Title: Re: Speaker for sound simulator.
Post by: red181 on November 11, 2007, 11:23:43 PM
what sort of motor comb are you running, I tried an 8ohm 10watt speaker with a JJC mtb, (even with a speaker tube which made a massive difference), but the graupner 600 bb turbo motor I use was too noisy at higher revs and you couldnt hear the sound unit. I wondered if a bigger watt speaker would work, never got the opportunity to try cause the sound unit was faulty and returned. I will try again, so if anybody can advise what speaker ( or maybe 2 speakers like a computer) I should use I would be greatful.
Title: Re: Speaker for sound simulator.
Post by: DickyD on November 12, 2007, 12:33:37 PM
With my JJC sound units I  have used the Mylar 87mm 8 ohm speakers from Maplins, cost 4.83 ea.
These are being used with the Turbocat diesel unit and can be heard up to 50 yards away with no problem.
I too used a speaker tube as the instructions advise.  O0
Title: Re: Speaker for sound simulator.
Post by: red181 on November 12, 2007, 11:07:25 PM
Dickyd, are you using 1 or 2 speakers? Have you got any video of it in action?
Thanks
Title: Re: Speaker for sound simulator.
Post by: Colin Bishop on November 12, 2007, 11:31:29 PM
Just out of interest. How do you set the right sound levels for simulators and when should you use them? There was a big lifeboat at the Mayhem Weekend where the "rumbling" exhaust sound seemed to be just right and very realistic but at another event somebody had a tug with a triple expansion engine effect which you could hear from 30 yards away. I've been on steamers with this sort of engine, Waverley and Lake Lucerne steamers, and while you can certainly hear the engine if you are standing next to it, from outside the ship you don't hear much if anything at all.

Even diesel ships don't sound loud from any distance, usually the only sign of them starting up is a bit of extra vibration if you are on board accompanied by a lot of black smoke from the funnel.
Title: Re: Speaker for sound simulator.
Post by: DickyD on November 13, 2007, 09:40:33 AM
Dickyd, are you using 1 or 2 speakers? Have you got any video of it in action?
Thanks
Hi, I am using just the one speaker and it is more than adequate as it should not be heard from to far away.
Have got my wife working on a video. O0
Title: Re: Speaker for sound simulator.
Post by: DickyD on November 13, 2007, 10:09:42 AM
Just out of interest. How do you set the right sound levels for simulators and when should you use them? There was a big lifeboat at the Mayhem Weekend where the "rumbling" exhaust sound seemed to be just right and very realistic but at another event somebody had a tug with a triple expansion engine effect which you could hear from 30 yards away. I've been on steamers with this sort of engine, Waverley and Lake Lucerne steamers, and while you can certainly hear the engine if you are standing next to it, from outside the ship you don't hear much if anything at all.

Even diesel ships don't sound loud from any distance, usually the only sign of them starting up is a bit of extra vibration if you are on board accompanied by a lot of black smoke from the funnel.
Colin I only have the Turbocat diesels fitted in mine so far and the volume is set so that I can hear them start up when first put in the water and can hear them accelerate away to about 40-50 yards. Mind you the boats are a fast mine sweeper and a fast patrol boat which tend to be noisy in real life. We have a chap in our club who has a steam tug which you can only hear when it is close inshore. I agree, the volume should not be to high as to be unrealistic. Jim of JJC stipulates the size of speaker etc and he is right with what he specifies.   O0