Bachmann Class 37 with a pair of 23mm "mega bass" speakers

[buggerlugs]

Greetings.

After reading all the positive reports about "mega bass" speakers I thought I would modify another Bachmann Class 37 to accept a pair and compare them with the 1st install I did on a Class 37 which used a 40 X 20mm speaker under the fan and a 58 X 22mm speaker in the fuel tank. (see pics posted on 19-08-2011)

I modified the chassis to accept a pair of these speakers which I fitted into "home made" enclosures, as I was told that enclosures for the 23mm speakers are not available to buy. After reassembling and checking all was well on the "programming track" I fired her up (By the way I used another Zimo "multi drive"sound decoder) Mmm,sorry not impressed with the results. Even after playing around with different volume settings I have not been able to achieve the "growl" I get from my 1st install (and yes I have tried the speakers is different positions i.e. both up or both down) So as soon as time allows I will be removing the "down" facing speaker and replacing it with a 58 X 22mm in the fuel tank. Hopefully this will sort things out.

I hope the above will be helpful to those of you who are thinking of fitting a sound decoder to a Class 37 and can't decide which speakers to go for. I am currently working on my Heljan "Lion" into which I am fitting a pair of 40 X 20mm bass speakers and if they sound as good as the Class 40 I've already done using the same speakers, I will be really pleased.

Thanks.

[pauliebanger]

Great photos of your machining prowess, thanks for posting.

 

I must say I am surprised that after all that work on the machining and enclosures the results were disappointing. I've had good results from them, but more especially the 28mm version.

 

Maybe the small volume of air in the machined enclosure is restricting/dampening the cone? Some of the enclosures I have fabricated are about the same external dimensions as the one's you have made, but with a larger volume internally.

 

Whatever the reason, it's a good lesson for us all that there is no 'one size suits all' so this is really useful info.

 

I am building a test rig with a variety of speakers/enclosures, so if it ever gets finished, I will be able to demonstrate how each performs using the same sounds.

 

BTW did you know that there is a 'test tone' of 200Hz sine wave built into Zimo chips for testing?

 

Kind regards,

 

Paul

[tractor_37260]

Like Paul, I'm rather puzzled also by your dissapointing sound quality. I fitted a pair of exactly the same speakers, facing down, in the fuel tank recess of a Bach 37, using thin plasticard for a lid, to form a sealed box directly under the motor, used with a 21pin Digitrains Multi Drive decoder. I'm OTM with the resulting sound, especially the much deeper "growl" making my other loksound fitted locos sound rather thin & tinny almost. I've yet to experiment with 28mm speakers as suggested by Paul/Cassey Jones, but would expect some further improvement to the sound.

 

BTW superb work on the chassis block

 

Regards

Ken

[buggerlugs]

Hi Paul & Ken,

 

Thank you both for your comments. I think before I give up on the M.B.speakers I will make up another pair on enclosures.

I will make them as big as possible whilst still being able to get the body back on and see if that makes any difference?

It's all got to come to bits again anyway, to put in the lighting loom. I will let you know how I get on.

 

Paul, can you tell me if it is possible to increase the "air brake release" volume on the Class 37 file, as compared to my Class 40 it is very quiet.

If yes how do I do it? Thanks.

 

Regards B.L.

[pauliebanger]

Hi Paul & Ken,

 

Thank you both for your comments. I think before I give up on the M.B.speakers I will make up another pair on enclosures.

I will make them as big as possible whilst still being able to get the body back on and see if that makes any difference?

It's all got to come to bits again anyway, to put in the lighting loom. I will let you know how I get on.

 

Paul, can you tell me if it is possible to increase the "air brake release" volume on the Class 37 file, as compared to my Class 40 it is very quiet.

If yes how do I do it? Thanks.

 

Regards B.L.

 

BL

 

Sorry, I have to ask a few questions first. Is this the Digitrain's Multi-Drive Class 37? If so, is the sound too quiet in all the sound sets? Are you asking about the automatic air release made before moving off? Or the manual air release on F keys 5 or 13 (depending on the set in play)?

 

The sound sample is not particularly quiet, and the default 'as programmed' setting is -0dB, ie full volume.

 

It is possible to change the volume setting of each sound sample on Zimo decoders using only a DCC controller. However, it is not possible to change volume above 'full volume'.

 

When I have your answers, I'll explain how to set the sample to full volume. If this does not work (because it is already at full volume) there are two other routes that I can suggest.

 

Paul

[pauliebanger]

Like Paul, I'm rather puzzled also by your dissapointing sound quality. I fitted a pair of exactly the same speakers, facing down, in the fuel tank recess of a Bach 37, using thin plasticard for a lid, to form a sealed box directly under the motor, used with a 21pin Digitrains Multi Drive decoder. I'm OTM with the resulting sound, especially the much deeper "growl" making my other loksound fitted locos sound rather thin & tinny almost. I've yet to experiment with 28mm speakers as suggested by Paul/Cassey Jones, but would expect some further improvement to the sound.

 

BTW superb work on the chassis block

 

Regards

Ken

 

Ken,

 

Do your twin 23mm speakers physically touch each other, side by side? Or are they mounted separately within the tanks? How have you arranged for the sounds to leave the tanks?

 

Paul

[buggerlugs]

 

BL

 

Sorry, I have to ask a few questions first. Is this the Digitrain's Multi-Drive Class 37? If so, is the sound too quiet in all the sound sets? Are you asking about the automatic air release made before moving off? Or the manual air release on F keys 5 or 13 (depending on the set in play)?

 

The sound sample is not particularly quiet, and the default 'as programmed' setting is -0dB, ie full volume.

 

It is possible to change the volume setting of each sound sample on Zimo decoders using only a DCC controller. However, it is not possible to change volume above 'full volume'.

 

When I have your answers, I'll explain how to set the sample to full volume. If this does not work (because it is already at full volume) there are two other routes that I can suggest.

 

Paul

 

 

Hi Paul,

 

The Zimo "multi drive" I have in my Class 37 is from Digitrains. I was talking about the automatic brake release when setting off in "multi-drive", but have just tried it on "normal" function (CV 265 set to 103) and on the "notching" function and they all sound the same with the exception of F13 (notching) and strange as it might seem this appears to be a bit louder? As I said before I am comparing the Class 37 brake release to my Class 40 which also has a Digitrains Zimo sound file fitted but as you are aware this is not a "multi-drive".

 

Thanks again B.L.

[pauliebanger]

 

 

Hi Paul,

 

The Zimo "multi drive" I have in my Class 37 is from Digitrains. I was talking about the automatic brake release when setting off in "multi-drive", but have just tried it on "normal" function (CV 265 set to 103) and on the "notching" function and they all sound the same with the exception of F13 (notching) and strange as it might seem this appears to be a bit louder? As I said before I am comparing the Class 37 brake release to my Class 40 which also has a Digitrains Zimo sound file fitted but as you are aware this is not a "multi-drive".

 

Thanks again B.L.

 

BL,

 

It's possible. It is the same sample in each case, but the decoder can play it at different sound levels according to CVs assigned. If one is louder, then there is a possibility that some of them have been 'turned down' (or attenuated).

 

Let's try the automatic release before the loco moves off. This sound is allocated to the 'Start Whistle' sound slot so that it triggers automatically.

 

We are going to use the pseudo programming mode, CV300. You need to follow this exactly as there is no information displayed to help you unless you are fortunate enough to be using a Zimo hand set, MX31 or MX32.

 

Turn off all sounds, and put your controller into programming mode.(either should work). Call up CV 300 and enter the value 132. This ensure we are going to vary the volume of start whistle only. Do what you need to come out of programming mode.

 

Your controller will no longer operate the loco in the usual way. This special Zimo mode allows the decoder to react differently to normal commands fom your controller. When you have finished and saved the changes, the controller reverts to normal operation again.

 

Press F key 0 and you will hear the sound, in this case air brake release. Do not touch any other keys yet. Your throttle control is now a volume control. Use it up and down to obtain the maximum sound level possible. You may need to press F key 0 to play the sound again during this process, that's OK. (if you hear a 'cuckoo' jingle, you have hit the wrong key).

 

When you have the max volume, you can save the value by pressing Fkey 8. You will hear the 'confirmation' jingle, a sort of electronic warbling sound. This stores the value and ends pseudo-programming for now. Your controller is back to normal and you can run the loco to test the change.

 

If you are happy with the result, you can repeat the above for each of the sound sets. (CV 265, values 101,102,103 and 104).

 

(If you use Decoder Pro from JMRI you will find a tool, written by Nigel Cliffe of this parish, to make these changes graphically.)

 

If it's still not loud enough, we need to make more sweeping changes.

 

Let me know how you get on.

 

Paul

[buggerlugs]

Hi Paul,

 

Many thanks for that, I will of course let you know how I get on.

 

Regards B.L.

[ian-p]

Hi Paul, could you point me in the right direction for this tool in decoderpro? I have downloaded the new 2.13.1 version and have two of these Multidrive decoders.

 

Many thanks, Oh sorry for Hijacking your thread BL

[buggerlugs]

 

Hi Paul,

 

Many thanks for that, I will of course let you know how I get on.

 

Regards B.L.

 

Hi again Paul,

 

I have tried adjusting the "air release" volume as per your instructions but it must have already been set at max volume as you suspected, because when I tried to increase the volume the sound level actually went down.

Thanks again for your help I think I will leave things as they are.

 

Regards B.L.

[pauliebanger]

Hi Paul, could you point me in the right direction for this tool in decoderpro? I have downloaded the new 2.13.1 version and have two of these Multidrive decoders.

 

Many thanks, Oh sorry for Hijacking your thread BL

 

Ian,

 

No problem.

 

This is a Jython script. From the Decoder Pro start page select 'Panels' menu then 'Run Script...'

 

From the alphabetical list that appears, scroll to the end and select 'Zimo_pseudo_programmer.py'

 

All the instructions you need are then on screen.

 

Behind the scenes, the script runs the sequence I described, but the gui makes it easier to avoid mistakes.

 

Paul

[pauliebanger]

 

Hi again Paul,

 

I have tried adjusting the "air release" volume as per your instructions but it must have already been set at max volume as you suspected, because when I tried to increase the volume the sound level actually went down.

Thanks again for your help I think I will leave things as they are.

 

Regards B.L.

 

I hope you were able to put it back to where you started!

 

To complete the answer, the other two methods I can think of are:

 

1. Increase the total volume for all sounds, then, using the technique outlined above (but different CVs of course) reduce the volume of every other sound. This would be tedious and difficult to maintain a good balance between all sounds, but it would be possible 'in extremis' to make any sound relatively louder in the mix.

 

2. Have the decoder re-blown with a customised sound project where the above has been done within the project before loading.

 

Kind regards,

 

Paul

[pauliebanger]

Hi again Paul, I have tried adjusting the "air release" volume as per your instructions but it must have already been set at max volume as you suspected, because when I tried to increase the volume the sound level actually went down. Thanks again for your help I think I will leave things as they are. Regards B.L.

 

BL

 

Just occurred to me. When you press Fkey0, the file plays at max volume, whatever is set in the project. Any movement of the throttle will produce a lesser volume setting until you reach max again.

 

For example,

 

Say the sound is set at 80% in the project, using pseudo programming, when you press F0, the file plays immediately at 100% (ie louder than set in the project). When you move the throttle control (from zero) the sound will begin to play at Zero volume, progressively up with upward throttle movement to maximum. it is possible to save a new setting at either extreme or at any point in between.

 

This is a bit academic if the sound is already set at max.

 

Paul

[buggerlugs]

Hi Paul,

 

Thanks very much for your input,and yes I was able to get it back to how it was. Like I said I think I will leave it well alone for now.

How's it go "if it ain't broke don't mend it" !

 

On another topic, how are you getting along with your "Deltic / Class 55 file?

 

Regards B.L.

[pauliebanger]

No further progress on that, sorry. Too many irons in too many fires at the moment..

 

I'll let you know.

 

Paul

[tractor_37260]

 

Ken,

 

Do your twin 23mm speakers physically touch each other, side by side? Or are they mounted separately within the tanks? How have you arranged for the sounds to leave the tanks?

 

Paul

 

 

Hi Paul

After cutting holes in the tank bases, the speakers were araldited in, one in each tank, separated by the step/ridge in the tank base. An piece of plasticard was used, to cover over the tank area of the chassis, forming a sealed box, with glue also around the protruding wires/holes. I would normally just drill a series of holes in the tank base, as this also helps to protect the speaker. However with the MB speaker, and the larger possible movement the cone/diaphram which could ? hit inside the tank base and cause distortion etc, I decided a large ACCURATELY CUT clearance hole for each speaker a was better option.

 

One point that did concern me with this fitment, one of the speakers is very close to the motor armature, on trial fitting the magnetism effect was very apparent, the speaker "latching" on to the motor casing at any opportunity. Question is, will this effect the performance of the speaker/s ?

 

PS A small tip for anyone trying this mod: for the hole size use a 1p coin - perfect for the 23mm MB speaker.

 

Ken

[Nigelcliffe]

This is a Jython script. From the Decoder Pro start page select 'Panels' menu then 'Run Script...'

 

If using the DP3 window, the "Run Script" command has moved to the "Actions" menu.

 

Note that you have to be on the running track, not the programming track, regardless of whether you use the manual method or my script.

 

 

From the alphabetical list that appears, scroll to the end and select 'Zimo_pseudo_programmer.py'

 

All the instructions you need are then on screen.

 

Behind the scenes, the script runs the sequence I described, but the gui makes it easier to avoid mistakes.

 

Indeed, there is nothing magical, just a computer remembering the button pushes made so far, putting meaningful labels on the buttons, and only offering buttons which do something useful at that stage of the sequence.

 

 

 

- Nigel (script writer)

[Nile_Griffith]

 

 

Hi Paul

After cutting holes in the tank bases, the speakers were araldited in, one in each tank, separated by the step/ridge in the tank base. An piece of plasticard was used, to cover over the tank area of the chassis, forming a sealed box, with glue also around the protruding wires/holes. I would normally just drill a series of holes in the tank base, as this also helps to protect the speaker. However with the MB speaker, and the larger possible movement the cone/diaphram which could ? hit inside the tank base and cause distortion etc, I decided a large ACCURATELY CUT clearance hole for each speaker a was better option.

 

One point that did concern me with this fitment, one of the speakers is very close to the motor armature, on trial fitting the magnetism effect was very apparent, the speaker "latching" on to the motor casing at any opportunity. Question is, will this effect the performance of the speaker/s ?

 

PS A small tip for anyone trying this mod: for the hole size use a 1p coin - perfect for the 23mm MB speaker.

 

Ken

 

 

Hi there!

 

I don't play around with speakers in trains I must admit, but do spend a lot of time with speaker drivers in cabinets for large P.A. systems, so this advice is down scaled somewhat.

 

Any kind of magnetic field in close proximity to your driver is going to effect it. In simple terms the magnetic field from the motor will damp the physical movement of the speaker driver. So at low volumes particularly at mid to high frequencies the speaker is not provided with sufficient "ummph" (very technical term) to overcome the damping effect.

 

As for placing the driver in a sealed enclosure you run the risk of creating further damping. If the speaker drivers movement or excursion, increases or decreases the volume of the enclosure by a certain amount, then the movement of the speaker diaphragm will be damped. In a nutshell. When the speaker diaphragm moves backwards, it will compress the air within the enclosure. If the air can not move out of the enclosure then the increased air pressure may stop the speaker diaphragm from reaching it's full excursion. Opposingly as the speaker diaphragm moves outwards and away from the enclosure this will cause a drop in pressure. In a small diaphragm the lower pressure at the back of the diaphragm will allow the normal air pressure on the front of the diaphragm to push it back. Essentially you speaker enclosure needs to be ported to allow air out when under pressure from the backward movement of the speaker and air in to maintain equal pressure each side of the speaker when it moves forward.

 

Sealed enclosure speakers generally have quite limited frequency responses and also require, for want of a better expression. More power to mechanically overcome these air pressure problems. With teeny tiny speakers fitted to Loco's their strength of mechanical movement would be quite weak so as to allow for better frequency response.......... if that makes sense.

 

Hope this helps.

 

p.s. In my world Sub speakers kick off at about 18 inches. 23mm would be considered a high frequency driver.... lol

[tractor_37260]

Interesting comments, I did suspect the closeness of the motor's magnetic field could/would effect the sound quality. Plan to try the removing the "lid" from above the speakers, the front of the speakers still being separated from the rear by the chassis/body etc, the same idea in reverse as fitting/sealing a speaker directly under the roof fan grill. A hole (port) is an alternative, but just how big does one make the hole ? AFAIK, port sizes are based/tuned to the overall volume of the box/enclosure at the design stage.

 

As for sealed inclosures requiring more power, my shoe box sized Hi Fi speakers (Linn Kans) provided they are driven by a proper amp (Nap 250) can make some much bigger speakers sound wooly/boomy etc in comparision, with very poor definition.

[cassey jones]

 

As for sealed inclosures requiring more power, my shoe box sized Hi Fi speakers (Linn Kans) provided they are driven by a proper amp (Nap 250) can make some much bigger speakers sound wooly/boomy etc in comparision, with very poor definition.

 

 

Ken,

Nice sounds, I know what you mean .... put a Sondek on the front end and wow!

[buggerlugs]

Hi again to all,

 

I made another pair of enclosures for the 23mm MB speakers.I have made them as big as I possibly can to fit into the available space.To gain another couple of mm I machined a bit more out of the chassis so the speaker/enclosure is

just clear of the drive shaft when fitted,so in total I have gained about 3mm in the internal depth in the second pair of enclosures.

Not a lot but what a difference! I would say that this loco's sound is now on par with the first one I did where I have a larger bass speaker in the fuel tank and a 40 X 20mm under the fan.Oh I also tried drilling holes in to the enclosures to act as ports but I'm afraid this didn't work and the holes are now sealed up.

Thanks for looking. B.L.

 

[pauliebanger]

Thanks for posting your results. We can breathe a sigh of relief now.

 

Kind regards,

 

Paul

[trisonic]

I suppose that both speakers are actually in phase with each other? Out of phase and you will get frequency cancellation issues i.e. they will sound weak.

 

Best, Pete.

[boxbrownie]

I guess if your worried about issues with the magnetic fields interferring, how about just placing a small sheet of soft iron between the speakers and the motor, that will give isolation between them.