Something never seen before (I think)...
 

Before I get into this, I want to say that this is NOT a serious project by any means. It was just one of those whimsical things that grab me from time to time.

A while back, I was driving my Revo around the yard while listening to headphones when a car went by with a booming stereo. So, I figured: Why not install a stereo in the Revo? An idea was born.



And just in case you think you didn't read that right: Yes, a stereo in a Revo.



First, I started by tearing apart a set of old computer speakers that had a blown internal amplifier. So, now I had a 2.5" full-range driver. Not exactly deep bass material, but whatever.

Since the Revo doesn't have much room on the inside, I thought I'd make a speaker box that would sit in the rear "bed". After making a few measurements and a trip to Lowes for fiberglass resin and some thin wooden dowels, and a trip to Wal-Mart for some fleece, I started assembling the box. The pics below show some of the various stages of the fabrication.


The wooden frame made of 1/4" square dowels with fleece wrapped around it:
http://scriptasylum.com/forumpics/rcstereo_1.jpg


Several layers of fiberglass inside and out and a bit of sanding:
http://scriptasylum.com/forumpics/rcstereo_2.jpg


Test fitting the driver. Perfect fit!
http://scriptasylum.com/forumpics/rcstereo_3.jpg


After a little textured paint (to emulate speaker carpeting), a speaker gasket, and some port tubes:
http://scriptasylum.com/forumpics/rcstereo_4.jpg


I didn't have any Theille-Small parameters for the driver, but I figured I'd make the box as big as I could and then port it for a little extra 100Hz response. The result was adequate at best. Oh well. Can't make a hi-fi out of junk I guess.

So, now I need a car amp.... but to scale. So, an I found a small and cheap 7W mono amp circuit. The amp chip is really designed for low-power car headunits, but an amp is an amp right? The IC will work well from ~8v all the way up to 18v+, but needs at least 14v to get the rated 7W out on a 4ohm load. Easy enough on 14 NiMH cells I think. After some assembly and shoe-horning into a RadioShack enclosure fitted with appropriate connectors:


Internals. Pretty basic stuff. You like the blingy gold heatsink?
http://scriptasylum.com/forumpics/rcstereo_5.jpg


The amp all buttoned up:
http://scriptasylum.com/forumpics/rcstereo_6.jpg


The amp and "subwoofer" box together for size comparison:
http://scriptasylum.com/forumpics/rcstereo_8.jpg


So, a little velcro to hold down the box in the Revo truck bed, a little power wiring to my batteries, and hookup to a tiny flash-based MP3 player is all that is needed to have tunes while zooming around! Please don't mind the poor Crowdpleaser paintjob - artistic flair is not my strong suit!


A last pic showing the box mounted in the truck
:
http://scriptasylum.com/forumpics/rcstereo_7.jpg


Yeah, the sound isn't the best, but is surprisingly loud when running around. Of course, you wouldn't want to race or bash with this stuff on there, but it was a fun project nonetheless. :)

Maybe with a nicely painted hummer body, a true stereo would be an interesting project. Maybe even have a true subwoofer. :)

I have got to hand it to you, that that thing is sweet!!! I didn't think that it would fit in the bed that well, but it doesn't look like it doesn't belong there. You seem to be the first to try so many different things.

You wouldn't happen to have a movie of the revo driving witht he music on,. would you?

Awesome job again.

Thanks! Mainly, it was a combo of me being bored and looking for a project while waiting for my next conversion. :)

No, no video.... yet. I may snap a quick one sometime.

Man Brian, how can you mock us like that... telling us about a new conversion, but not telling us what it is? Shame... :)

Maybe a hint? :027:

Someone has WAAYY too much time on their hands!!lol Nice job too though, (i am also a car stereo nut).

RC: Actually, I had done this before I got the CRT.5. So that was my next conversion, and it still isn't truly done since I'm now waiting for a spur...

bdebde: lol, tell me about it! Boredom is a bad thing. My actual 1:1 vehicle stereo sounds a "tad" better.

Man that is dope! Now you just need to record the sound of a nitro engine and play that through it.oh no,hang on..:007:

Well, since nitro sounds like a loud mosquito, I'll just take some recordings of my backyard tonight and boost the volume. :)

lol. That's gotta hurt battery runtimes.

Brian,

You are a trip! I was in tears reading this thread! You are a genius. Whacked, but a genius!

Excellent work! I loved it!

I'm a pro-audio & video engineer by trade so I totally appreciated this "whimsical field trip".

Thanks for making me smile & laugh this morning!!!!!

Brian,

Heres a crazy though t for you.

How about a nitro "noise cancellation system'????

Add a mic & signal inverter and perhaps you'll have the first silent nitro truck!!!!!

(p.s. don't forget to credit me for the inspiration!!! LOL!)

Well, 7w is only 0.5A at 14v, but you NEVER see that kind of average current draw unless playing a non-varying sine wave. Average output is more like 2-3w. At any rate, I won't be running it in a race so it hardly matters. May make a shelf queen someday with a real stereo complete with sub. More a conversation piece than anything functional. :)

Procharged: lol! I think it would take a bit more power than 7w to cancel that noise! Probably be easier to make a true muffler. Or better yet, just keep it BL and have more power and quiet to boot!

Yes, It would take much more than 7watts! Fun to think about though.

I helped an automaker several years ago design a cancellation system for one of their premier cars.

That must have been fun to work on! Did the transducer mount inside the exhaust driveline, or near the exhaust opening? If inside, it must take special materials to handle the heat! I imagine the system consisted of a microphone, an amp with phase control, and a special speaker?

Multiple mics, multiple transducers, a digital signal priocessor and lots of critically placed damping material on the chassis to minimize NVH plus some alterations to the sheetmetal structure to enhance rigidity and minimized resonance. Quite a few alterations really. And nothing plumbed directly into the exhaust, the concerns were noise radiating from the exterior of the pipe.

Also....

I use "quite steel" in some of my designs/alterations. Are you familiar with quiet steel?

No, never heard of it.

Quiet steel consists of two sheets of high grade maleable carbon steel with a sheet of polymer laminate "laminated in between".

The result is virtually resonance free steel. Somewhat sound absorbing even.

I have samples here that are credit card sized. The steel sample when thrown on the table sounds like a plastic credit card. It's amazing.

Ford started using the material in valve covers to reduce emission of valvetrain noise, and they've added it to some parts of their trucks and cars now. The newest F150/F250 is amazingly quiet!

You must be joking, haha - excellent!

I got the perfect little amp for that and it's stereo the heatsink might be a little big though it's good for about 15 rms a channel.

Jeff

Whoa! A whopping 15w rms/ch would blow my tiny speaker. :smile:

Oh no you just need more speakers..........and stronger springs.:yes:

Jeff

Thats so cool! but really you have too much time on your hands. Reminds of back in 1986 when I had 2 15" pyle pros and a kenwood 1020 bridged in the back of my 1976 toyota corolla station wagon. Stereo was worth more than the car. But It was the loudest in town. Now I cant stand those kids with the loud systems now now I guess I am getting old.

Wow a 1020 that was SOTA back then high steppin! I remember when my mom bought a 84' Caprice Estate Wagon it had a Yahama YCT800, and a set of proton 3 1/2's with a Proton 222 and in the rear were a set of A/D/S 300I plates driven by a Power Plate 120.

Jeff

What funny you dont see many amps now that had as low of a harmonic distortion as that amp did. It was anextremly clean amp. Not much power though. I think back then it was over $1000. I picked it up for ~$600.

Pretty cool Brian, I like it.

It's been a while since I was really into car audio but I was there when the stuff first came out and got to watch the progression until the DB Drag stuff started then I was pretty much out. Everything seems optomized to run at 2 ohms and in some cases even lower so I think that had a lot to do with it, that and the poor quality of the designs. I remember when you opened up an amp it was full of componets then a lot of cheap manufacturers would use IC amps like in Brians design to drive their output stage directly and the specs on those are not the greatest the quality suffered as well. The only one I knew that had anything close to a quality amp was Matts they used the LM10 and 12 to drive their output stage and they were pretty good. About a year before they came out I was looking through the Digi Key catalog (when it looked like a magazine instead of a phone book) and ran across that chip and was like that would be great to run straight to the output stage. Well that IC was about $75 and I didn't have the money to get one (If I knew about samples back then :party:) I would have taken that and the TIP 35/36 and made an amp while I was still in highschool. I ended up making an amp when I went to tech school, but that one used 2 2N3055's for the output stage.

Ahh memories.

Jeff

waterproof-ed?

Now that is serious extra time but the thought did cross my mind for a rc to ride withe music but it was funny what if it played music to actually do it is awesome great ingenuity Only on RCM you find stuff like this to see it created. Next I would like to see an amphibian RC so who is going to make it? Brian:whistle:

Wow, this thread somehow got brought back from the dead!

j57ltr: Those "amps on a chip" have their advantages and disadvantages. The good thing about them is that 90% of the circuit is integrated, so it takes less space, can have better noise rejection, and is simpler. The bad thing about them is that the heavy current stage is also on there, is generally pretty weak, and you might run into thermal issues since it's so compact. However, you could use the chip to replace the differential input, voltage amplification, and pre-output stages, and use outboard transistors for the final stage.

edep345: No, not waterproofed. Although, it wouldn't be all that difficult to do. A little silicone around the various openings of the amp, and a weatherproof speaker would be all that's needed.

swiftneed: You mean like a boat with wheels?

No, a truck that floats!:lol:

Boat with wheels...

Truck that floats! i dont live in a swamp, so there is more land than water:yes:. How bout this, i will make my Blizzard float, tracks and floats!, beat that!:na:

I had a high lift that was completely waterproof. I could run it in 4ft of water, or if I could still see it... Even had 3rd channel lights so if I lost it I could switch them on...

Yeah Brian perhaps a sealed case, that would allow the RC to be taken into water from land, as if you want to put your brushless boat into water you just roll it right in but I believe the brushless would be to much power

Ok a BoatRunner OK a TruckfloaterRunner OK I will leave the names up to the guys dont forget the cooler for the beer:intello:

Ask Nick ( Rummy ) about floating trucks...

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:mdr: