danlrc

An assortment of exciters was delivered today. Will be trying them in my Tamiya KT.
Will have pics, results, and hopefully representative sound files to post.
Plan on mounting at various places in hull, in turret and maybe on a soundboard suspended under the hull.
Here are some lower hull options.

danlrc

Will be trying variuos speaker/exciter setup options today.
A key point: If the Tamiya speaker has 4ohm impedance, the total impedance of the exciter or any combination of exciters and speaker needs to have a total impedance no lower than 4ohms. Otherwise, the amplifier might be overloaded and blow out. If the load is higher than 4ohms, amplifier power will not be fully used.
So the trick here is to get the low power Tamiya amp put out more sound than the 4ohm speaker alone puts out. That means the exciter setup, still kept to 4ohms, has to be more efficient in putting out sound than the speaker. So trial and error in variuos setups will be needed.
Here are some links to calculate the impedance of various speaker/exciter combinations.
http://www.speakerimpedance.co.uk/?a...age=calculator
http://www.bcae1.com/spkrmlti.htm

Freaky Dude and Dan (YHR), you're the experts on all this - please correct me if i have any of this wrong (I probably do). Do you know the Tamiya amp max wattage rating? I wish tank sound was higher on my spending priority list - I know other systems are great and have higher power output. I 'll just focus on the Tamiya system to see what it can do with exciters.

Best,
Dan L

YHR

No expert on the Tamiya system but the Tamiya system is 4 ohms, so as long as you keep your exciter array at 4 ohms or more you will not damage the Tamiya amp. You will find that these exciters are very dependent on the size and density of the material being vibrated. The denser the material the more low end it produces. This low end though is inversely proportional to the volume. I believe a combination of material will give the best results. I have 15 watt amps available tt me and I will be experimenting with those when the high power exciters arrive. I am going to try hobby plywood speaker material and see what I get.

Directly to the plastic hull results in a good deep rumble.

Green Amphibian

Dan does attaching things to the plastic hull affect the sound?

Herman

YHR

No. Other then they will get a good rattling.

danlrc

Did some quick testing with small 13mm/4ohm/3W exciters. I think they are too small to add much sound effect if only one is used. Also tried the 19mm/8ohm/5W. That may be the size I use. YHR is going to test the 24mm size, but he has a more powerful amp than the stock Tamiya amp in my KT.
Since the total ohms for the speaker/exciter array has to be no less than 4ohms, I'll try adding a 4 ohm exciter in parallel to the Tamiya 4ohm speaker, and an 8ohm exciter in parallel to to those, for a total impedance of 4ohms.
The 19mm exciter fits exactly into the round fan opening on the KT rear deck, so I'll try putting it there. The 13mm will go in the turret.
There is no way to get an exciter on the floor with all the torsion bars in the way. An exciter with a panel would fit between the speaker and rear axle, but I have a smoker there.
Definitely lots of placement options to try.....

Green Amphibian

These are really sounding like a good thing. I am following this in anticipation of getting one in my Hetzer.

Herman

danlrc

Seems that judging sound effects in test installs is hard. The speaker volume seems to be lower with the 19mm/5W exciter added. But, again, hard to tell.
I have a smartphone and just downloaded a sound meter app called Sound Meter Pro. Cost was $1.50. Will try using the sound meter to make actual measurements of tank sound with different exciter setups.
Also has a vibration meter. Maybe that will work to measure deep bass rumble.
App is available for iOS and droid.
https://play.google.com/store/apps/d...oy.sound&hl=en

YHR

It would be interesting to see some actual data. Volume is an interesting thing for your brain to decipher. Ever ride in a vehicle all day with the radio on. You park your vehicle and then start it up in the morning, and the radio just about blasts you out of your seat, and yet the volume control is exactly where you left it. The brain auto compensates it seems.

Anyway with the exciters the material you are vibrating plays a huge role on the output, and the sound is very clean.

Having said that the 4 ohm Tamiya system is pretty loud, I found the foam board to create more volume then the hull plastic, but when attached directly to the hull it had more bass.. Both of the exciters you have and the one I have are limited to about 4 watts. That is why I went with the 20 watt , 24mm one I am hoping at 15 watts the volume from one attached directly to the hull gets me to the sweet spot on volume..

I believe ultimately it will take two exciters to get the best results. The big payoff is in the space savings these create.

Try using some foam board or a less dense panel then the plastic or metal of a tank hull.

Imex-Erik

So I think Traxxas is using exciters now too They may be speakers but until I get a test model to play with we wont know for sure. I was fiddling with them before they announced them this weekend and it seems ok. When you put your hand on the top body you kill the sound by half or so but it really vibrates your hand. I couldnt get too close for pictures but I would be interested to see if they end up being exciters! Here are a few pictures for you guys:

I'm not sure how much I can post yet, I know they are publicly announced but not sure if I can post the pictures I have. I'm sure plenty of them are already out, I just dont want to get in trouble

YHR

Yes those look like exciters. Interesting as I stumbled across a site that supposedly has a patent pending for use of exciters in a model. ( Not Traxxas) As a producer of exciters that last thing I would want to see is a patent granted on an application of my hardware that would limit my sales. The transducer is patentable, but an application on how it could be used seems to fall outside of patent law.

If it doesn't then I have dibs on using tissue paper to wipe ones behind.!!!!! Now there is an application of existing technology I could get rich off of.


The fact you are showing pictures of what Traxxis has out is just one more case of this being a natural progression of current sound technology. These ideas have been floating around for years. I was at a trade show a couple of years ago and I guy was selling transducers to change anything into a speaker, so nothing new here other then existing technology starting to makes its way into the modeling world.

Imex-Erik

I'm really surprised this wasn't done earlier actually. I mentioned this to my boss a few months ago actually. I had a way different approach of using a certain tank sound card though
I did a quick search and seen lots of other pics are out so might as well show you the unit...

danlrc

Made some measurements. Used the sound meter phone app, so values are not calibrated, but the relative values are a bit useful. But only a bit, because the decibel scale is so screwed up. Did a little research. The decibel scale is not linear. 1db is about a 25% sound increase, 3db is about double and 10db is about a ten-fold increase. And decibels are not additive, so two speakers at 90db each will not give 180db of sound, but about 93db. So the db numbers shown below are hard to interpret. But it's data, so here it is:

Reference values: thunderclap 120db, chainsaw 110db, blow dryer 100db.

Exciter test results (measured from 20" away):
1. Tamiya King Tiger, stock speaker setup, engine idle sound: 115db (very loud)
2. 19mm,4ohm,5W exciter mounted on 2 x 3.25" x 1mm styrene rectangle: 112db (noticeably less loud than stock speaker) Note: exciter in open air, not inside tank.
3. As #2, but 2 x 3.75" styrene: 112db (size of rectangle didn't increase sound)
4. As #2, but 2 x 4.25" styrene: 112db (again, no sound increase)
5. Exciter above, mounted on 2 x 4.25 x 1/16" walnut sheet: 114db (deeper and louder sound than with plastic)
6. 19mm exciter mounted directly to hull inside the KT rear deck ventilation fan opening (exact fit): 106db (only fairly loud, but good quality sound)

My general takeaways:
- Results will still be hard to share because the decibel scale is so wierd.
- The 115db level is very high, can harm hearing (when right next to source). 120db supposedly can cause instant hearing loss.
- "Quality" of sound is important, but decibels don't reflect the character or quality of the sound, only "loudness".
- The Tamiya speaker generates very high volume, and it will likely take YHR's 24mm exciter(s) testing to get comparable volume.
- The 19mm exciter I used will likely not be able to generate as loud a sound level, but I want to try two exciters, one in each fan opening.
- The KT rear deck vent fan openings are perfect for exciter placement - sound quality was very good. Maybe two 19mm's will generate enough volume. That's next for testing.
- I'm still thinking of exciters as additions to the stock speaker, but they can likely replace the bulky speaker if multiple 19mm exciters or the larger 24mm exciters are used.
- Mounting exciters to hull right under rear deck openings seems a good place to start experimenting. (See Erik's post on the Traxxas exciter mounting)
- Exciters in the turret need to be tried.
- I don't think vibration effects on tank structure/parts will be an issue. The tanks take a beating running over terrain anyway.

Just a start- a lot of potential...

ausf

Thanks for compiling that data.

It seemd like this is definitely a viable direction to take.

Imex-Erik

Wow! 115db really?? I know at 118db in my car I had to wear headphones or my ears would start to hurt! That was of course with 5000W though

Imex-Erik

Edit: double post

Lord Haw-Haw

I know, grew-up around race cars, 115db is loud. This is louder then a real tank. I'm going to replace my car's MB Quart Q system and get some Tamiya's! Damn could have saved me some money's!

YHR

Yes remember this is a downloaded app Dan is using. I wouldn't put much faith in the db number itself, but the comparative nature of the findings is useful.

danlrc

Really? I doubt it, but have no idea. The sound meter was my phone with an app called Sound Meter Pro. Totally uncalibrated. As I said, the value is likely only in measuring differences between the test setups.
The stock KT is really loud though - uncomfortable when it's on the bench in front of me. Any idea what the amp output is? One thing I did when I built it was use thru screws and nuts at the four top corners of the speaker box, right into the metal chassis. The normal setup was just screws in the plastic to hold the box lid on. I used the thru bolts not for sound, but to use the speaker box to stiffen the sides of the metal chassis.
The whole tank does vibrate and is loud. I wonder if the rigid speaker box mount helped sound?
Anyway, I'm thinking the Tiger sound is good enough for now. Will look at exciters in teh Pershing where I can use the speaker space for other stuff, and in my tugboat build.
Waiting to hear how Dan does with the 24mm size he has coming.

Strato50

I like the idea of mounting a slice of hardwood panel inside the tank, that's still versatile and slim enough to be a major space saver.

I'd like to see what happens when these are mounted inside the larger Tiger / KV turrets, directly or indirectly.

Imex-Erik

Yea I used to have a full Kicker system back when they were #1 and for a while I was rocking a 4k watt JL audio amp until it fried it. There was no way you could comfortably sit in it at even half volume. I thought it was top end until I went to a public show and had it tested (the competition guys all were in a totally different class). I did get like 8th place but MAN some of those guys were pushing 20K+ watts and that was about 10 years ago. I would be interested in seeing one of those MTX Jackhammers though... 22" subwoofer

Green Amphibian

22" subwoofers, I'd like to see you put those in a tank! ROFLMAO

Herman

Imex-Erik

Ha! I don't even have subs in the house anymore! I just have a nice set of DJ headphones I use now. My neighbors and I get along, I don't want to change that! But yea 22" subwoofer, it is pretty insane: https://www.mtx.com/jackhammer-car-subwoofer only 8k watts! Youtube has quite hilarious videos of them, I would love to see one in action. I've always been an audiophile and make sure I have great mids and highs to go with my bass. I can't imagine trying to pair something with that....

hiramekisama

Can someone post a video of their result?

I got a 8ohm, 25W exciter: http://www.parts-express.com/dayton-...8-ohm--295-210

My mini amplifier is also 8ohm, 10-50W. Comparing the exciter to my 3.5" Audio Pipe speaker, the exciter is very unimpressive lol. The bass is great, high vibration. The sound is about half as loud compared to my 3.5" speaker. I tried on styrene and cardboard surfaces.

YHR

As has been mentioned the best result might be a combination. I can't comment on the 25 watt exciter as I have not tested it yet. The bass response is great on the Exciters, but I agree the volume might not be as loud. I was hoping the 25 watt exciters being driven by an amp would help that. How many volts are you running to your amp. ? 12 votls to the amp will make a world of difference.

However to me loud isn't the only measure of performance. Quality of sound and the throaty throttle response is more impressive then a blarring tank. Unfortunatley Video does not capture this well.

But once I get my 25 watt exciters I will put together a video to show the results. I will place a glass of water in the tank to try and demonstrate the difference in bass response.