In the case of the Kato fuel tank, poor output results from front and rear air pressure combining. I agree as designed this will cause distortion with thin material diaphragms. Placing the speaker in a sealed enclosure in the locomotive gives better performance because of the improved isolation. The spring effect from a sealed enclosure will always provide stable output with low distortion. I do not dispute this. But there are other factors to consider. Poor low frequency response in a tight space is one of the trade-offs. Many customers may not miss this. Some will appreciate the difference when using other options.
BTW I install professionally; 30 years audio tech experience; taught electronics for 8 of those years. I only put this in so you know I'm not a novice or dabble for fun.
To be fair, there are situations where a sealed enclosure produces the best, loudest sound. Especially in narrow hood locomotives with limited air space and lots of places for air to escape.
The challenge when using an infinite baffle is to make sure the front air pressure has no way to mix with the rear air pressure. In some cases that means turning the body and chassis into a larger sealed enclosure OR creating a large isolation enclosure such that the "reach" of the front wave cannot extend to the back wave's area; in other words the rear wave chamber ideally extends beyond the wavelength. While this is easier to achive across the board with O gauge and larger scales, many HO scale large locos (E-units for example) have better than satisfactory results. I should mention isolation and sealed are very similar in this respect, because the preventing front and back air waves are the goal. Sealing is the easiest, simplest way to create isolation. Place a high-bass speaker in a sealed enclosure vs a GS4 tender and the results are quite noticeable. Place the same speaker in the end of a foot long tube sealed only at the mounted end and the results are also noticeable.
My concern is the idea that there is only one practical way to "skin this cat" so to speak. I contend there are other methods that give loud clean output with deeper richer tone. Brand of speakers, diaphragm material, power rating all are factors. The speakers sold by TTX ,AHD, Digitrax, etc., are not the only options. This not about your integrity. I'm sure your customers are quite happy with the results of your experience and ability. But many people read this forum and many opinions are based on what is read. Let's give everyone the opportunity to experiment using theories from all sides. I'm sorry the other methods have not given you good results. It does not mean they do not work at all.
Carl in Florida - - - - - - - - - - We need an HO Amtrak SDP40F and GE U36B oh wait- We GOT THEM!
davidmbedard Ill say it again. Speakers in the fuel tank is a bad, bad idea. I have seen and fixed the result of the magnet-next-to-everything issues with this arrangement. Not to mention the magnet/magnet issue when crossing over an uncoupler magnet. In our hobby a baffle needs to be sealed, we are not hooking up a guitar here, we need all the help we can get. David B
Ill say it again. Speakers in the fuel tank is a bad, bad idea. I have seen and fixed the result of the magnet-next-to-everything issues with this arrangement. Not to mention the magnet/magnet issue when crossing over an uncoupler magnet.
In our hobby a baffle needs to be sealed, we are not hooking up a guitar here, we need all the help we can get.
David B
Isolation can be achieved sucessfully without a sealed enclosure; sealed enclosures are recommended because it greatly increases the success rate of an installaton; It reduces the need to engineer a taylored enclosure.
In addition, most of the speakers use a mylar cone or similar material as opposed to coated paper; mylar cone speakers used have a rating of 0.1 watts to 0.5 watts and are very efficient. A sealed enclosure allows high output while protecting the speaker cone with a cushion of air inside the enclosure. This reduces distortion and extends speaker life. The problem with speaker failure on the BLI F-units was related to high output with poor baffling.
However, not all installations in HO scale and scales larger require a sealed enclosure. The other less efficient speakers used in our hobby are used typically in notebook computers. These speakers are not in a sealed enclosure in this application. The speaker cone is less prone to damage due to flexing and have a rating of 0.5 to 1.5 watts. An infinite baffle is used because it provides a richer tone while taking advantage of the resonant quality of the notebook's casing. Steam locomotive tenders and covered wagons with large spacial bodies benefit greatly from this approach.
Sealed enclosures are typically have small area, hence reduced lower frequency output; when using older Soundtraxx decoders (pre-Tsunami) there was little low frequency output, especially with a coupling capacitor rated at 33 microfarads. You would not need a larger enclosure because there was'nt much content at the low end to exploit. The newer decoders (QSI Revolution, Soundtraxx Tsunami) with direct coupled amplification and low frequency response have a wider frequency range and can produce lower tones. In addition the greater air pressure produced by direct coupled amplication (3db loss with capacitor coupling at the factory-supplied value) with certain locomotive bodies can experience increased output due to its resonance.
In some cases you can have the best of both worlds; i.e., placing the speaker in a sealed enclosure and directing the open cone toward the loco body (try this with you next F unit install point the speaker assembly up instead of down toward the track. This creates a sort of acoustic dipole, increasing output while enhancing frequency response.
I encourage anyone to try different baffling methods; each locomotive is different; chassis, body density, shape, available air space all play a part. In some cases there is very little room for an enclosure or more importantly, you are forced to use a smaller speaker to include the enclosure. Larger speakers with a proper infinite baffle design (successful air isolation from front and rear speaker air pressure) will sound better than smaller ones with a sealed enclosure.
While I know we are not connecting a guitar, the laws of sound acoustics still apply here. Just ask the engineers that design locos with sound. Isolation of front and rear air pressure is the key, I am stating there is more ways to achieve this than one.
Hi David,
I read your post on painting superliners and learned from it. Want to say that I met modelers at a club that had sound in their 1:87 engines. They took their engines apart so visitors could see the electronic parts inside. All of them had the speakers facing down. One of the modelers told me that tonys trains owner hooked it up that way based on his method. tony the owner who is a sound expert. In O scale most of our sound engines had the speakers in the fuel tank pointing down too.
davidmbedard jbinkley60 davidmbedard 2 things.... 1. Never put speakers in the fuel tanks. They are magnets and will pick up anything lying around. 2. Even High Bass Speakers require a baffle to operate properly. There is no room for a proper baffle in the fuel tank. David B The Katos have a baffle built into the fuel tank. No.....a baffle is an air-tight enclosure behind one face of a speaker. Kato has included a speaker holder, in my opinion, not a proper baffle. Again, I strongly suggest that you do NOT put speakers in the fuel tank. Over time, the sound will become more and more distorted. There are much better options for speaker locations. David B
jbinkley60 davidmbedard 2 things.... 1. Never put speakers in the fuel tanks. They are magnets and will pick up anything lying around. 2. Even High Bass Speakers require a baffle to operate properly. There is no room for a proper baffle in the fuel tank. David B The Katos have a baffle built into the fuel tank.
davidmbedard 2 things.... 1. Never put speakers in the fuel tanks. They are magnets and will pick up anything lying around. 2. Even High Bass Speakers require a baffle to operate properly. There is no room for a proper baffle in the fuel tank. David B
2 things....
1. Never put speakers in the fuel tanks. They are magnets and will pick up anything lying around.
2. Even High Bass Speakers require a baffle to operate properly. There is no room for a proper baffle in the fuel tank.
The Katos have a baffle built into the fuel tank.
No.....a baffle is an air-tight enclosure behind one face of a speaker. Kato has included a speaker holder, in my opinion, not a proper baffle.
Again, I strongly suggest that you do NOT put speakers in the fuel tank. Over time, the sound will become more and more distorted. There are much better options for speaker locations.
In audio electronics, the definition of a baffle is a partition that checks (isolates) the front sound waves of a loundspeaker from the rear sound waves. Case in point - ever seen a guitar amplifer /speaker combo? the rear is open. Old radios and televisions from the early days were designed the same way. A sealed enclosure is a different type of baffle. The reason they are so popular in model trains is they ensure isolation between front and rear waves. The small areas we deal with have more opportunity for front/rear air mixing due to air pressure. Infinite baffle designs also work in our hobby; greater care is taken to create isolation. One of the benefits of infinite baffle design as it relates to us is it can produce deeper richer sounds. In some cases such as in sound outfitted E units and F units the shell's resonance can result in a richer louder sound than is produced with just a sealed speaker. To reinforce my statements read the tech paper from QSI Industries: http://www.qsisolutions.com/pdf/loco_acoustics_design.pdf
On the issue of Kato locomotives, I agree the fuel tank install can cause the problems described. However with someone passionate about keep the roadway clean and devoid of debris will not have the magnet pickup problem. Taking steps to seal the speakers with hob-e-tac, photo mounting putty or similar will result in improved results without damage to the speakers as a result of mechanical overextension.
jwhitten The second half of the clip, which you have marked as "high bass" definitely has a deeper, throatier sound. I asked my wife to listen to see which one sounded "better" without telling her anything about it-- she just heard the sound without seeing the video. She also said the second half was better.
The second half of the clip, which you have marked as "high bass" definitely has a deeper, throatier sound. I asked my wife to listen to see which one sounded "better" without telling her anything about it-- she just heard the sound without seeing the video. She also said the second half was better.
Thank you both
Nice to have an outside opinion
TerryinTexas
See my Web Site Here
http://conewriversubdivision.yolasite.com/
davidmbedardIn fact, with the Tsunami, you can adjust the equalizer to match the speaker. The decoder you have in there is made for smaller speakers in the high frequency range.
I agree. Most sound mixers automatically cut off some bass to help prevent distortion and wasted energy. If you will note, the QSI decoders often have two sets of files for the same engine. One set is often the files mixed for larger speakers.
For a Tsunami, boost the lower end of the eq, or set the CV for speaker size.
If this is the older DSD-100 series, then try dropping the capacitor on the speaker lead and see what happens. This acts as a high pass filter.
Don - Specializing in layout DC->DCC conversions
Modeling C&O transition era and steel industries There's Nothing Like Big Steam!
Engineer Jeff NS Nut Visit my layout at: http://www.thebinks.com/trains/
Does anyone know if the high bass speakers will fit into the fuel tank sockets that Kato provides now on its newer diesel HO units ? Based upon the dimensions, it appears the high bass speakers may be too deep. I am wondering if anyone has tried this ?
davidmbedard The issue isnt the speaker, it is the decoder. If you had a Tsunami in there, then you would hear a difference because it supports the lower ranges. In fact, with the Tsunami, you can adjust the equalizer to match the speaker. The decoder you have in there is made for smaller speakers in the high frequency range. David B
The issue isnt the speaker, it is the decoder. If you had a Tsunami in there, then you would hear a difference because it supports the lower ranges. In fact, with the Tsunami, you can adjust the equalizer to match the speaker. The decoder you have in there is made for smaller speakers in the high frequency range.
Well that would explain the small difference in sound
This loco has a early model soundtraxx decoder
C&O FanI use my first High Bass Speaker I was so impressed i bought 2 more ... However after testing and comparing it really made very little difference
I was so impressed i bought 2 more ... However after testing and comparing it really made very little difference
I would think that since the tender was not sealed, just adding a baffle on the existing speaker would have made just as much difference.
I use my first High Bass Speaker on my Rivarossi F-19 Pacificin a DCC sound Conversion
http://cs.trains.com/trccs/forums/t/150663.aspx
I was so impressed i bought 2 more
and put one in my Berkshire
Replacing the normal speaker
With a High Bass Speaker and a circular baffle enclosure
I thought the baffle would really help since before
the tender body was the baffle and was not air tight
because of the large slot opening for the tender draw bar
However after testing and comparing it really made very little difference
The whistle sounds the same to me
there may be a slight improvement in the chuff tone and the bell sound
See what you think
http://www.youtube.com/watch?v=w_TmnO62QUk