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[portside II]

well said Bob
i have the turbo cat jjc sound unit and a while back i asked Jim (jjc) why that sound  and if he could do one with a bit more grunt ,the sound is taken from the engine room and not from outside the hull , would like one that has the sound from the stack's ,even if it does sound like the exhausts are blowing .
There is a small tug at goole (little shuver) that has a bige petrol engine in it and when working all you can here is this loverly purring sound  music to my ears .

If jjc has closed its doors what about the sound units and other products from him ,are they replicateable (can we copy them legaly) .

I mean the base of these devices is an eprom chip which can be read and duplicated ,legaly of course  ,and then fitted onto a board which has a purpose built heat sink .

Reading the posts on here there has been mentioned the use of water and air as a cooling solution but dont forget the transistor also requires heat to opperate efficiently and having cold water pumped around its extremities may actually be too much ,the heat sink is the way to go and it is also a good base to mount your module to the hull/whatever.
daz

[malcolmfrary]

The point about heat generated in olde portables - these were low power devices, intended for the listener to be quite close.  Even so, if you took the lid off and examined the output transistors with your thumb, you would note that you then had a sore thumb.  In the case of the ghetto blaster, the audio amps carried substantial heatsinks, and they were well vented.
If you want the sound of three Packard V12s a few yards away to realistically jiggle everybody's bowels in the open air, then you are talking POWER. 
A typical passive HiFi loudspeaker was deliberately made very inefficient, conversion was considered good at about 1%, and the rule of thumb for a given room was "10 watts per drive unit per 1000 cu ft per channel".  The open air is a BIG room. 
The speaker setups that we use are not HiFi, but restricted to "normal speech" plus maybe an octave lower, max 3.5KHz, min whatever can be managed.  We do not use multiple drive units and filters, so efficiency can be much higher (don't know, ask somebody else) and what is needed is a solidly built speaker (bass/lower mid) with a powerful magnet and long throw, and an amplifier built to drive it.  This for continuous loud sounds.
For intermittent sounds, the need is much less.  A speaker rated at a couple of watts can handle rather more in short bursts such as a ships horn.  An ocean liner would need to move a lot of air with the rather deep sound, a warship can have a much smaller speaker for the "whoop".  The speaker in my corvette is about 45mm diameter and the whoop can be heard over 50 yards away, about 2 and a bit miles in scale terms.

[bigfella]

Precisely why you do not need to go too big on amplification. What you want is SCALE sound to match your Scale boat. I think if the sound module puts out too much sound for the size of the model it ruins the effect.

Malcolm: I used to work with PAs for bands and in the clubs it was worked out that each punter absorbed 1watt. Believe it or not some bands went to some gigs with only a 1000watt PA system where the crowd was just under 2000, and they wondered why they could not be heard.

Regards David

[red181]

bigfella dont forget we have to "overscale" our sounds as we have to overcome the noise of the electric motor, in my case a loud graupner, but good points raised

[tigertiger]

I have seen small external speakers for laptops/mp3 that have two speakers of less than 2", run on 5.1v (from USB) and do not get hot. They were very loud, beefy with good base response and with internal amp. Total size for unit with two speakers was about 9" x 2.5" x 2". ( I did not buy this particular model as it was relatively expensive for China retail (about 20quid), so cannot give any more details.) What I can say is that they were not tru Hi-fi. But I don't think we need hi-fidelity for ship engine sounds, do we.

As for water cooling, as has been pointed out, you don't need a pump. there are units used for motors that work by differential pressure as the boat moves on the water. So unless you plan to be stationary, this would help.

Edit 2 post together - Admin.

[BlazingPenguin]

dont want the robbe "angry wasp" sound!!

Ahem....I was taken to task for a comment like this, one rule for some, different for others? 

I swapped the fitted heatsink for a section of extruded aluminium from an old roller blind chassis, no probs since, but it did get very hot before that.
I will be after someting like JJC's steam unit for a steam tug if your doing one like that?

(No woodpeckers were harmed in the posting of this reply)

[pakirk]

Hello all
Well LOTS of exelent comments.
I will ready through them all and take note.

Thank you all
Anthony
RCMW

[pakirk]

Update.
Well I have been very busy.
 Lots of prototyping and tested and experimenting with different ideas.
This is what I have settled on.
Big heat-sync - Expensive and bulky.
 Water cooled- Erratic and unreliable works fine for ESCs but boat has to be moving or a pump running. Pump has to be filtered and clogs up easily.
  Fan force cooling.
Constant, reliable and controllable thumbs up.
Tests on the fan cooling was excellent reliable and neat.

The System
The AMP and sound units are separate units.
The AMP is in a 40x40x20mm based box (The same as my ESCs) with a 10mm deep fan.
15W power output to a 4Ω speaker running at 18V
I decided to design the AMP around a 4Ω speaker because they are more readily available 8Ω are getting harder to get. 4Ω speakers are used in cars. They are more efficient to drive from a battery system also. Hence why they are used in cars.
The input is correctly balanced to a Pre AMP driving the power AMP and has input and output filters.

The sound module is again in a 40x40x20 box. They inter-link into each other (NO LINK CABLE REQUIRES saving £3 a shot ). They also inter-link to the AMP unit.
For additional sounds simply add another sound unit next to each other. If you require more power then simply add another AMP unit.
If you do wish to separate them, then simply use a standard servo extension lead.
You don’t require a servo Y slitter either again saving £3, your ESC plugs directly into the sound units.
The units are opto isolated from you receiver insuring no interference, as was experienced with previous sound units out there.

Many of you have JJC Slaves and can’t use them because the master has packed in.  With a special conversion lead I do you can use JJC slaves with my system.....

Well they should be out on the market soon.
I have tried my hardest to keep the price the same as the JJC units (£40 for master), (£30 for slave), (£30 for AMP unit), (£3 for link cable and £3 for Splitter) , but there are lots more components evolved in my units plus a fan.

I don’t have a Master as such; it’s like the AMP unit and slaves. This is to give the users more flexibility.
So it’s looking like this:
Sound Module £30
Sound module and AMP purchased together £45 
Sound and motion Module £35
Separate AMP £30
Bearing in mind you DON’T need a £3 Y splitter or a £3 link cable .
I hope very much to hear your comments.

[Martin (Admin)]

Lot of work done there sir! 

We look forward to seeing hearing the prototype.

[david.harrison]

Guys, I would like to introduce my company - "Model Solutions of Canada Ltd." - www.modelsolutions.ca

We already have two different sound modules on the market and they are available today. They are WAY superior to anything else on the market, including those beloved JJC units!! There is no need for anyone to start developing a JJC replacement - we are already there!

They have a USB interface - you can download YOUR OWN sounds to them via a PC program that we supply with the module.

They use an extremely efficient Class D PWM power amplifier that delivers a full 12Watts of power into 8 ohms at 14V - i.e. a fresh 12V gel battery.

At 12V you can get 9 Watts and get this folks, NO heatsink, no fan, no heat - period.

Our current SFX4 series modules are 2.75" x 3.225" x 3/4"

They are at the higher end of the price spectrum CDN$169.95 and $139.95, but bear in mind what you are getting.

8 - 10 sounds
Total of six minutes of digital sounds
Full configurabilty via its PC interface
12Watts power - NO HEATSINK, NO FAN!!
Built in 16 channel R/C switch decoder
16 button keypad for the transmitter
8 auxiliary switched outputs
2 switched outputs can be configured to flash in sync. with any of the sounds
   (e.g. lamps in gun barrels) - completey user assignable.
USB cable
SFXPC application software + free sound editors - Audacity and others.

If you were to buy a 16 channel switch decoder from us , or other manufacturers, it would set you back CDN$150 just by itself.

The closest competitor to us is the Robbe unit at 135 Euros (CDN$203) and it only has six sounds, two aux outputs and IS NOT downloadable.

We are also developing some simpler, smaller, lighter, and cheaper units, our SFX5 series - availability May 2008.

Shipping costs to the U.K. CDN$56 - 5 business days, or CDN$30, 2-3 weeks.

1 CDN dollar is 50 pence.

Hope this helps.

David Harrison
Model Solutions of Canada Ltd.
www.modelsolutions.ca