I have one of the new U25 sound systems which did not work properly. I sent it to Aristo for service and it looks to me like they replaced what I believe is the voltage regulator and added a heat sink to it.
When I got it back I bench tested it and found that the system is much improved over the previous (pre2K) system. On the bench the sound was very good, once the balance was adjusted to my liking. However, the voltage regulator continued to get pretty warm. When the Voltage regulator over heats, it shuts down and then recovers, causing a pulsing or throbbing sound. This seem to be because the part is being forced to dissipate too much current which means that there must be a resistor that needs to be changed to a higher value or perhaps a resistor needs to be added to the input, to reduce the current. I don't know how this may affect the rest of the operation of the system.
The other thing I have found is, in real world operation, the sound is muffled. When I tried to figure out why it would be so different from bench to backyard, I read old information that, I think may be the problem (and solution) to this anomaly.
If you look at the way the speaker and sound system are installed in a U25 fuel tank, you will see that the speaker is not able to seat in the mounting position properly. Only the two side edges are touching where it is glued in place leaving large gaps forward and aft where the speaker frame does not touch. Further, in order to fit the circuit board into the fuel tank, there are several holes in the fuel tank cover.
MY THEORY is that the installation of the speaker and sound system have created a situation where the sound coming off of the back of the speaker, is canceling out a wide range of frequencies coming off of the front side of the speaker. Add this to the sound absorbing properties of the ground, which the speaker is pointed toward, and the sound that makes it to your ear has lost a considerable amount of energy.
I have heard from others that are extremely happy with the 2K RS3 sound boards and I need to get a couple of these. The speaker installation is totally different in the RS3 and should be adequate, making the sound much better. These new sound systems are very good units, it is just that there are a couple of things that need to be addressed on the U25 system. One is the overheating problem, the other is proper speaker installation, then they will be excellent
1. I installed a much bigger heat sink on the voltage regulator, which seems to have stopped the system from cycling due to excess heat.
2. I installed the soundboard inside the long hood of the U25 to get it out of the fuel tank, thus allowing the use of the original fuel tank and cover. This required an extended wire harness that I added a miniature connector to, for the speaker leads. The original (power) connection for the sound system, is a two pin connector mounted on a small circuit board which is then mounted with two screws and centered over a small hole in the bottom of the U25 frame. Removing the screws, holding this small board, allowed access to the hole. The battery harness can just barely be pushed through, followed by the reed switches and speaker harness. I reinstalled the power connector with the pins facing up and connected the sound system.
3. I modified the original equipment fuel tank by milling out semi-circular recesses into the sloped sides (of the interior) of the tank, allowing the speaker to sit much closer to the bottom of the tank. I removed about .03" of plastic from the boss (that is formed from the molded pocket which provides clearance for the weight mounting screws) in the fuel tank cover, directly above the speaker magnet. This allowed the original cover to be installed properly.
4. I glued the speaker in the fuel tank with silicone adhesive adding a bead of silicone all the way around the speaker frame to seal the front of the speaker from the inside of the fuel tank.
5. I glued .04" styrene over the holes left over from the (old) original sound system (molded in the bottom of the fuel tank).
6. I used mounting foam to secure the battery in the fuel tank, connected the speaker to the extended harness, installed the fuel tank cover and reassembled the loco.
This is a preliminary description of what I did to improve the sound of the new Aristo-Craft U25 sound system. I have not completed the modifications I have planned but I wanted to get some preliminary work posted for anyone looking for help with this system. When I complete my testing, I will formalize the techniques and add photos to help clarify the procedures.
Results:
The results are nothing short of fantastic. The sound outside is much improved. I could easily hear the motor sound 75 feet away but it is not overly loud from 8 feet away.
Future plans:
I will experiment with a few other modifications to this sound system to try and improve performance. My results and techniques will be forwarded to Aristo-Craft so that they can have some field notes to consider future mods to this otherwise fine system. One thing I will do is to add an additional speaker inside the engine hood and add wire screen in place of the plastic grills that are currently standard on the U25. I will post the results of these modifications as soon as I complete them.
Conclusion:
Buy a Sountraxx Sierra or Phoenix Sound Systems and save yourself some grief, but the speaker installation is still important. The new U25s are just starting to arrive at Aristo-Craft and they will have the open screens but I don't know about the speaker mount yet
Aristo-Craft dropped the PS Hobbies Line of Sound systems from their catalog shortly after I sent them my findings. Whether I had any impact on this decision is unknown. Aristo-Craft has been developing they're own sound system for a couple of years. Lewis told me that he has virtually stopped development and will be seeking another third party sound system manufacturer. I have also been told by others, not associated with Aristo-Craft, that PS Hobbies has discontinued their line of sound systems. RIP!
