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Jim, I installed one of these 3" speakers from a company called "Futurelec" in my Bachmann Mogul:



The speaker has a HUGE /DesktopModules/NTForums/themes/mls/emoticons/wow.gif magnet; with a Phoenix P5 board driving it, this thing is LOUD!/DesktopModules/NTForums/themes/mls/emoticons/w00t.gif  If I crank it up, I can hear the Mogul's exhaust echoing /DesktopModules/NTForums/themes/mls/emoticons/laugh.gif off the neighbor's houses!  (But I usually DON"T /DesktopModules/NTForums/themes/mls/emoticons/whistling.gif run it that loud, to keep the peace with the neighbors!/DesktopModules/NTForums/themes/mls/emoticons/blush.gif).  Price is VERY reasonable!  Here's a link to it:

[url="http://www.futurlec.com/Speakers.shtml"]http://www.futurlec.com/Speakers.shtml[/url][/url]

It's the third one down the page, called "Large Speaker".;)  Although rated 4 ohms, you shouldn't have any real problems driving it.

Tom
 

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Tom's speaker looks good and he does know what he is talking about. I normally go with Phoenix speakers but have gotten speakers from Johnathon of Electric & Steam ModelWorks. He has some really good speakers with huge magnets. Here is the link to his site. http://www.rctrains.com/Parts and Access 2.htm. He is also a sponsor of the RC Battery Forum.
 

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I don't think the size of the magnets is really all that important. It matters in terms of the wattage the speaker can handle, but we're not talking here about high wattage applications--you want to be heard outside, but really, how loud does it need to be? I have a 1 watt amp in a small scale railway soundcard--it's more than loud enough. More power equals more volume without distortion, but in my experience 1 watt has been plenty. Getting a bigger magne tisn't going to make the sound "better," though it might make it louder. I actually doubt that it will make it much louder, as it does not take a huge magnet to handle the what--10 watts?--that a phoenix card puts out. It's often said here that "bigger magnet=better sound" but I'm skeptical.

What's lacking in g-scale sound is bass, and that's always going to be true. I'm a bass player--getting a lot of low frequency takes bigger enclosures and bigger speakers. look at almost any band--the bass player will have an amp and cabinet twice the size of the guitar player. The bigger the speaker (not the magnet) the better the bass response is likely to be. But the way to improve sound in these things would be to work on the enclosure. People who design bass speaker cabinets are always working on ported vs vented vs sealed. The size and length of a port can make a huge difference in the sound of a bass cabinet.  There are a set of formulas for figuring the size of ports  relative to the size of the enclosure. I've been tempted to figger out the interior volume of an Aristo USRA tender, and see if I can tell what kind of port would work. I have one of those Kloss Model 1 radios, which has a 3 inch speaker in a small enclusre and gets remarkably good bass response:



Hey, it's about the size of an Aristo tender! Honey, let me just borrow that radio for a bit....

Rather than looking for big magnets, I think the thing to do would be to go to a speaker like Kloss uses, designed for hi-fi, and put a port in the tender. The port is often just a carboard tube of a given diameter and length
 

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Also I think most of the time the speaker--often called the "driver" in audio-speak--is much less important than the cabinet design. Or rather, the thing you need to get right is the fit between the driver and the cab. The makers of audio speakers will just look at the specs for a driver and design a cabinet around it.

I'm thinking that the boiler of a big steam loco might make a nice enclosure, but it'd be hard to hide.
 

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lownote is spot on about what makes a speaker sound good. Let me add to that, having worked in high fidelity and stereo business for about 11 years back in the 60's and 70's (audio physics hasn't changed much since then) and having built many speaker enclosures in a variety of installations (albeit none as tiny as a G scale tender). The audio amplifier in the sound card even at 1.0 or 1.5 watts (what kind of watts I would ask- that's a whole 'nother discussion..) must have sufficient frequency range so as to be able to reproduce the full range of sound - including the bass - and pass it to the speaker with relatively low (inaudible) levels of harmonic distortion.

There are several other issues at work as well - amplifier "damping" (the amount of control it exerts over the voice coil when it vibrates in and out of the magnet's field which generates back-emf and can muddy up the sound), speaker cone resonance (has to do with the material it's made out of and the suspension used around the edge of the cone, and speaker efficiency (determined somewhat by the stiffness of the cone suspension and precision of the voice coil assembly - how narrow the gap is between the coil and the magnet opening and ferrite core).

When all is said and done, many of the best sounding speakers in small applcations have relatively small magnets. If you take apart that Kloss radio, you may be surprised at the speaker. But the enclosure significantly affecst the sound quality - and to get the most from it, it should be "tuned" to the particular speaker you have selected, based on certain specs like cone resonance and surface area and other factors. Whether tuned port, sealed enclosure, labyrinth (part of Bose's "secret") or what ever, there are ways to max the frequency response from these small speakers. Problem is....if we have to mount all of the R/C, sound cards, and batteris in the tender...that doesn't allow us to build a tuned enclosure. Enter the trailing car "woofer"......
 

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I have two Phoenix P5 systems. One uses the 3" that comes with a the "complete" Phoenix system and one is the special 3" from Jonathan at rctrains.com. The one from Jonathan is clearer at higher levels.

I don't know the specs or who makes the ones that Jonathan sells.

I believe the P5 can put out up to 6 watts.  It is fun to crank it up once in a while :D
 

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jeepersinco:

You did not specify what sound system is to be used.  If running a Sierra SoundTraxx system, do NOT run a 4 ohm speaker load (regardless of what others may have said).

If you want to run the specified 4 ohm speaker, you will need to put two in series (for 8 ohms), or use at least a 3 ohm  1 watt resistor in series with the speaker.  The Sierra will not tolerate less than about 6 ohms or it starts to "motorboat"  (sounds like someone doing a "raspberry" sound) as it can't put out enough current to sustain the load.
 

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Some speakers are more efficient than others. With the P5 sound system, that isn't much of an issue. With the Soundtraxx systems, efficiency really counts.

I have some 2" speakers that are much more effective at producing bass sounds but they are not ass efficient as the Phoenix speakers Therefore, I won't use these speakers with a Soundtraxx system.
 

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Discussion Starter #10
I'm using a QSI DCC sound and control card which requires a 8 ohm speaker. RC Trains thought that the speaker they had with a larger magnet might not fit in the Connies tender. It was too deep and would interfere with the curcuit board. I'm going to try and measure this weekend. 

Has anyone else installed one of their speakers in a Connie tender?
 

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Someone else also was experimenting with the tubes.  Wonder how they turned out.  Later RJD
 

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Hey guys.   

I'm glad to hear some folks (that seem to know about it) discussing just how critical the rear enclosure is.  I spent hours messing around trying to improve the sound on my speakers and found by accident that an simple tube open on the end resulted in incredible sound volume and quality gains.(regardless of the speaker type)   I mean the difference was stunning.  The longer the better 6, to 8 to 10 inches or a little longer providing if I remember right, optimal sound gains.  All this of course if you have the room in the tender.  If  you have the room and are just sticking a small sealed rear enclosure, you aren't getting the sound you could out of it.  (But If you don't have the room, you don't have the room so...)   But, all of my MTH engines have had their speakers replaced and open tube enclosures installed the full length of the tender.   I have a video (#21) on my DCS installs page under the Mallet section that demonstrates the difference in sound between the stock MTH setup and the new speaker with full rear enclosure.  I don't know how it comes across to others on the video but in real life the effects are simply stunning.   On the Mallets I used tubes (I use PCV in the vandy tenders) on, if I can vent a little of the sound from the inside of the tender out the sound is even that much better.  I agree with others that have said in the discussion long ago that creating good sound is a 'black art'. 
I converted an Aristo Mikado and Pacific (with long tenders that have the speaker I use and the tube enclosure) to MTH DCS for Nick Savatgy .  You can ask him how they sound.  :) 

Raymond
 

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I have been making sealed boxes for my speakers. I make them as big as the available space will permit. In one engine, I used a very nice speaker with a 2" cone. Foe an enclosure, I put the face of the cone into a 1 1/2" PVC end cap. This way, the sound comes off of the back of the speaker. It does porovide much better bass than you can get without an enclosure.

Very large enclosures are not very practical in many cases because I also have to get batteries, radio and sound boards into the same space, usually the tender.
 

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Rayman, that's very cool--thanks for sharing that.

Did you do any experimenting with the length and width of the tubes? There is a standard set of formulas for "tuning" ports: you adjust the port size to empasize certain frequencies
Here's a chart:


www.homerecordingconnection.com/news.php?action=view_story&id=33

There's a more elaborate link with calculators here:

www.bcae1.com/spboxnew2.htm

Where is your port exiting? Aimed down at the ground would be the least obvious, but you'd get more length if the port opened, say, on the "front" of the tender where it faced the loco cab.

I don't think capping the speaker will have muc effect. The issue in a small enclosure like a tender or a boxcar is always going to be bass. If you ported the enclosure you'd get more bass and more efficiency (more volume)

A bass guitar's low "E" string is 41 hz..  Most people can't hear a pure 41 hz. tone very well and ost cabinets don't actually aim to produce a lot of sound that low: they aim to produce that harmonics of that frequency and your ear "fills in" the missing frequencies. Most of human hearing is in the midrange frequencies, say 400 to 1000 hz. You want to bump the low midrange, which people hear as "bass."

An Aristo USRA Long tender is roughly 14x3x4. That means 168 cubic inches, roughly a tenth of a cubic foot. Very small. The chart in the link above desn't go that low. To do this right you'd need some specs from the speaker manufacturer, the "Q" and the "V" ratings. But absent that we can make a guess: I'd bet a 1 inch by i inch port would mke for a much "fuller" sound
 

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Ray, can you show a diagram or picture of your speaker in the tube?

My dad was a tinkerer, but never a finisher. I remember a radio box he started with 2 speakers mounted in cardboard tubes of different lengths. The speaker was at the back end of the tube. It sat around in the basement for years but he never built the radio for it. When I was 12, I hooked it up to a little tape player. It really sounded great!
 

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Awesome information Lownote!   Your last bit on the 1 by 1 inch port being about likely optimal I think is exactly right.  I currently vent (port) the sound from the inside of the tender currently by raising the coal load on my Mallet vandy tender so there is some air space between the tender and the back of the coal load.  It sounds best lifted to at a certain point, but not all the way off.  I haven't experiemented with porting on any of the tenders, but now that we've talked about this I think it's resparking my interest in this area.

Here is what I build for the vandy tenders.  This is using a stock MTH speaker.  I have to work the cut PVC elbow quite a bit and leave the back of the tube open.  For the other tenders I use paperboard tubes.  It's very tricky to get in the tender.  On the diameter and length, it all depends on the tender.  I use the largest I can up to the diameter of the speaker itself.  Since the engines sounded so good with just this (and I say just this as converting and getting tubes in all the tenders was a lot of work as it's not as easy as it might first appear to get a full length tube in the tender itself  and then have it seal against the speaker properly.  

Basically the sound from the end of the tube is then released into the remaining airspace in the tender.  Somehow this makes a big difference when compared to small sealed enclosures or just the speaker by itself just relying on the tender as the rear enclosure. 





Hey Torby.  Really interesting that it sounds like he was putting a speaker at the end of a tube facing into the tube.   I need to try that to see how that works.

The way to test this tube effect is to take rolls of duck tape and add them behind a simple 3" speaker one at a time effectively creating an ever longer tube.  From there you can try and cover the back of the tube with your hand to vary the 'port' to see what difference it makes.  I've found for my ear it was best to leave the back just left wide open.

Hope this helps some and thanks for sharing your info and experience!  Great discussion!

Raymond
 

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I think the way to do this would be to set the speaker in the tender, then set th port, the tube, in the tender so it's facing out somewhere--basically you'd have to drill a 1 inch hole in the tender somewhere. I'm very tempted to try it, although I've been on a run f terrible luck with locos lately--I've been knocking thing dow ad burnign components and just generally messing up. I need to let the stars realign or something
 
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