I have some of those amplifier modules, they'd be a good choice. If you use the amplifier, you can probably stick with the 8 ohm speaker in the master and not sacrifice volume if you don't run with the slave.
That's a good point about running alone. This also puts the kibosh on the two 4-ohm series method since you'd have no audio without the slave speaker present.
And going the other way, the nice thing about the amplifier is you could have more than 1 slave each with amplifier/speaker so volume would increase proportional to number of engines...rather than audio power being split (inversely proportional to number of engines).
I'm liking the amplifier idea more and more Stan. Adding a little power module and the amp isn't a big issue. 
Id thought about doing that to my williams EMD E-8..Would be nice to add speaker in the B unit and End A unit..
Here is an interesting Dallee speaker page that I linked some time ago. It addresses the size issue in most cases.
I did a conversion to a MTH Gas Turbine that used the dual speaker. Frankly it did not sound much different. Could have been the acoustics of the tanker. Did have a baffle. Each individual speaker still gets the same lower current if you have to raise the speaker impedance.
So anything that can keep the same impedance speaker is a better choice in my opinion. G
The amplifier is a good option, it doesn't impact the primary installation, just adds more volume in the other unit(s).
Wow! So much information. I need to spend some time and find the parts to make this happen. Thanks for all the help and great information you guys have provided. I'll be I touch if I have any more questions. Thanks again!
I've been searching "adding speakers" treads for info. This one from 2014 was very interesting with a lot of great input. Questions I would like to add are: Where is the best place to hi-jack the sound from, in an MTH, lead A unit when using an amplifier and speaker in the trailing units? After completing a project like this and hi-jacking the sound off of the lead A units speaker, then connecting that into the trailing units amplifier, I've notice the sound isn't as "clean" as the original source. Is it because along with the sound is fluctuating wattage from the speaker working? If it is, is it possible to hi-jack the sound off of the circuit board before the amplifier, or if that would be too difficult, is there a component that can be added to the wires coming off the lead A units speaker that would clean up the signal before reaching the secondary amp? I am using Craig rechargeable mini speakers with Bluetooth or aux input that have an unbelievable sound quality when used with Bluetooth or an mp3 player plugged into them.
Easy way to add a speaker to a diesel . . .
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Thanks Scrapiron, that looks like a political speaker, though. Impossible to clean the sound up from them. LOL
Dave Zucal posted:... hi-jacking the sound off of the lead A units speaker, then connecting that into the trailing units amplifier, I've notice the sound isn't as "clean" as the original source. Is it because along with the sound is fluctuating wattage from the speaker working?
Are you connecting the 2 speaker wires in the lead A to the AUX IN of your amplifier? What is the power source for the amplifier?
How does it sound if you disconnect the lead A speaker and only drive the trailing amplifier?
Is this PS2 5V, 3V, or PS3?
Stan2004, Yes the 2 speaker wires are plugged into the aux input. The speaker is battery powered. A charge last about 2 hours. Eventually I will and a 5 volt DC charging circuit from track power after I install pickup rollers. This is a PS-2, 3 volt board. The sound starts to become scratchy at about 3/4 volume. It's not extremely noticeable but I know it can be much better because of the quality of the sound that is produced out of these little speakers, from an un-amplified source, like an mp3 player. I believe the mini speaker's circuit is picking up the wattage driving the PS-2 speaker. Is there a way to filter that out of the line going into the aux input of the mini speaker so that I only have un-amplified signal? Or is it possible to solder 2 wires onto the PS-2 circuit board somewhere before the sound gets amplified?
I would not personally recommend attempting to tap into the audio on a PS/2 board. First off, the low level audio goes into an audio amplifier IC, so there's no place to really get to it without most likely creating more issues than you solve.
I was thinking it may be risky. Thank you for your input John. Do you know of a device that will dissipate the wattage and only allow signal to pass through so that I only have pure clean signal going into the aux input of the mini speaker?
I don't see the need to dissipate wattage. One of the issues may be the gross impedance mismatch between the PS/2 amplifier output and the aux amplifier input that is driving the secondary car.
Good point John. There may be an advantage then to going wireless with an FM transmitter to the FM cube speaker, or a bluetooth transmitter to the bluetooth in this speaker. I would rather not have the tether, but worry I would have to "pair" the bluetooth devices every time they were powered up. The FM may not be as clean as Bluetooth but at least they would begin to work upon power up.
So will the charger circuit operate while the amplifier is active? Most DC-powered mini-amplifiers connect one side of the audio input to DC- or local ground. If you use a bridge rectifier to convert track AC to DC, that audio input pin is 1 diode away from track voltage. The problem is neither side of the PS2-3V audio amplifier signal is at local ground. So if you connect 1 of the 2 speaker wires to you mini-amplifier when it is powered from a bridge-rectifier, I think this is akin to a short (one diode) between the speaker output wiring and the chassis which causes bad things to happen like blowing up the PS2-3V audio chip.
Next issue. The PS2-3V audio amp is of the so-called class-D ilk which means it is pulsing at a high frequency (250 kHz). The speaker essentially filters out these pulses so you only "hear" the audible content. As to that scratch sound, I'd want to put if up on an oscilloscope but what I'm thinking is the coupling capacitor in your mini-amp is creating spikes that somehow affects its behavior. I think virtually all mini-amps have coupling capacitors. If you feed digital pulses like from a class-D audio amp into a coupling cap it will generate spikes after the cap and into the amplifier circuit. If this is what's happening, you can filter/smooth these pulses using a low-pass filter. There is some math involved and if I were doing it I'd want to confirm this is indeed what's going on...but a filter might be a few inductors/capacitors and about $1 or so.
I realize this doesn't help you, but if I were doing it I'd consider an audio-transformer (a couple bucks). A transformer breaks the DC connection so you don't have the issue with grounds (unless you stay with battery-only power in the trailing engine). And since you're only coupling the low-level signal (rather than Watts of power) it gives a lot of flexibility in designing a filter to whack the class-D 250 kHz pulses from the PS2-3V amplifier chip.
Note that if you pursue the FM (or Bluetooth) wireless-tetherless approach, you still have the issue of those class-D pulses feeding your transmitter. Not all transmitters are equal since if I recall correctly the wireless FM transmitter mentioned earlier that willygee used worked just fine when driven by the speaker wires in a PS2 engine.
Thanks Stan, you may have just saved me a PS-2 board. I will stay away from charging from track power. It looks like a lot of research needs to be done here so I'll just have to be content with the sound I have. On a scale of 1 to 10 I'd give it a 7. My main concern was for video shots as the A-B-B-A rolled by the camera, to give all units sound as they rolled by.
stan2004 posted:So will the charger circuit operate while the amplifier is active? Most DC-powered mini-amplifiers connect one side of the audio input to DC- or local ground. If you use a bridge rectifier to convert track AC to DC, that audio input pin is 1 diode away from track voltage. The problem is neither side of the PS2-3V audio amplifier signal is at local ground. So if you connect 1 of the 2 speaker wires to you mini-amplifier when it is powered from a bridge-rectifier, I think this is akin to a short (one diode) between the speaker output wiring and the chassis which causes bad things to happen like blowing up the PS2-3V audio chip.
Next issue. The PS2-3V audio amp is of the so-called class-D ilk which means it is pulsing at a high frequency (250 kHz). The speaker essentially filters out these pulses so you only "hear" the audible content. As to that scratch sound, I'd want to put if up on an oscilloscope but what I'm thinking is the coupling capacitor in your mini-amp is creating spikes that somehow affects its behavior. I think virtually all mini-amps have coupling capacitors. If you feed digital pulses like from a class-D audio amp into a coupling cap it will generate spikes after the cap and into the amplifier circuit. If this is what's happening, you can filter/smooth these pulses using a low-pass filter. There is some math involved and if I were doing it I'd want to confirm this is indeed what's going on...but a filter might be a few inductors/capacitors and about $1 or so.
I realize this doesn't help you, but if I were doing it I'd consider an audio-transformer (a couple bucks). A transformer breaks the DC connection so you don't have the issue with grounds (unless you stay with battery-only power in the trailing engine). And since you're only coupling the low-level signal (rather than Watts of power) it gives a lot of flexibility in designing a filter to whack the class-D 250 kHz pulses from the PS2-3V amplifier chip.
Note that if you pursue the FM (or Bluetooth) wireless-tetherless approach, you still have the issue of those class-D pulses feeding your transmitter. Not all transmitters are equal since if I recall correctly the wireless FM transmitter mentioned earlier that willygee used worked just fine when driven by the speaker wires in a PS2 engine.
Here is a link to my setup to what Stan2004 is referring to. It is an absolute game changer.
