MM0141A

[Fowler4f]

I trust someone has fitted a sound decoder to this model. I haven’t removed the bodywork yet as I’m too busy. The paper work states it has a 21 pin decoder, but as photo shows on box it says 8 pin.

Could someone shine some light, 8 or 21 pin to save me time before I shell out over a £115 on a sound decoder. 
 

Thanks

[WRENNEIRE]

It has a 21 pin socket but no speaker
Ask whoever you plan to get your sound chip from for a suitable speaker for a 141, there are several but there is a bit of work involved in fitting one, I am sure it has been covered here somewhere

[Westcorkrailway]

If I had a DCC 141, would it run ok on DC layout or would it be benifical to remove the decoder? 

[Fowler4f]

14 hours ago, WRENNEIRE said:

It has a 21 pin socket but no speaker
Ask whoever you plan to get your sound chip from for a suitable speaker for a 141, there are several but there is a bit of work involved in fitting one, I am sure it has been covered here somewhere

Thanks WE, I have a few 141’s that I have fitted sound to already, it was the 8 pin on box that threw me. 

11 hours ago, Westcorkrailway said:

If I had a DCC 141, would it run ok on DC layout or would it be benifical to remove the decoder? 

It is fitted with a Blank 21 pin that allows it to run on DC. If you fit a DCC decoder , sound or non sound, you can set it to run on DC and DCC.

[irishthump]

22 hours ago, Westcorkrailway said:

If I had a DCC 141, would it run ok on DC layout or would it be benifical to remove the decoder? 

You can, but you need a DCC controller capable of reprogramming decoder CV's. Many decoders have this feature disabled as having it enabled when running DCC can cause erratic running.

[Westcorkrailway]

1 hour ago, irishthump said:

You can, but you need a DCC controller capable of reprogramming decoder CV's. Many decoders have this feature disabled as having it enabled when running DCC can cause erratic running.

Would it be a big job to remove the decoder altogether?

[irishthump]

1 hour ago, Westcorkrailway said:

Would it be a big job to remove the decoder altogether?

No. The hardest part is removing the body on the 141.

First remove the cab at the opposite end to the roof grill. this should just pull straight up with a little force. Remember to detach the ends of the handrails from the sides of the cab first, or they may well break. Many will tell you to remove the handrails completely before doing this but it can difficult (it's fiddley and sometimes they can be glued in place) and the body can be removed while leaving the handrails in place.

Working from the removed cab end  the rest of the body can then be levered up with some gentle pressure. Again, remember to unclip the handrails from the opposite end cab as that cab is attached to the body. Once the rest of the body is off removing the decoder and replacing the blanking plate is simple. Then simply replace the body and cab.

Here's and excellent tutorial that shows the process for installing sound which shows how to remove the body shell.

 

Edited July 17, 2022 by irishthump

[Joe Keegan]

On 17/7/2022 at 11:41 AM, Fowler4f said:

Thanks WE, I have a few 141’s that I have fitted sound to already, it was the 8 pin on box that threw me. 

 

This speaker is too long for a Baby GM as you will have to shorten the PCB and if you are not confident in modifying/shortening the PCB then do not modify/shorten the PCB.

The ideal speaker is the Baby Boomer which requires a small amount of filing the chassis/inside the hood and soldering the purple cables to the PCB marked SPK +/- . Polarity is not important in the Baby GM .

The Murphy Models 121 sound decoder is ideal for the Baby GM. 

[Sean]

17 hours ago, Joe Keegan said:

This speaker is too long for a Baby GM as you will have to shorten the PCB and if you are not confident in modifying/shortening the PCB then do not modify/shorten the PCB.

The ideal speaker is the Baby Boomer which requires a small amount of filing the chassis/inside the hood and soldering the purple cables to the PCB marked SPK +/- . Polarity is not important in the Baby GM .

The Murphy Models 121 sound decoder is ideal for the Baby GM. 

Polarity becomes important if double heading 2 or more sound units.

On 16/7/2022 at 11:46 PM, Westcorkrailway said:

If I had a DCC 141, would it run ok on DC layout or would it be benifical to remove the decoder? 

My recent experiences of this with esu chips;

The 121's actually ran a bit better than this without the hum but overall i found this mode very sensitive being particularly worse then DC or DCC over dirty track. Unless you are a tinkerer and have the means to regrogram loco's to tweak it I would probabaly just pull the chip out and run conventional dc

[Westcorkrailway]

35 minutes ago, Sean said:

Polarity becomes important if double heading 2 or more sound units.

My recent experiences of this with esu chips;

The 121's actually ran a bit better than this without the hum but overall i found this mode very sensitive being particularly worse then DC or DCC over dirty track. Unless you are a tinkerer and have the means to regrogram loco's to tweak it I would probabaly just pull the chip out and run conventional dc

I’ll have to ask the seller what DCC chip is in it…regardless I’ll still probably have to pull it out 

[Sean]

its a 5 minute job any road and the body has already been off once so shouldnt present any nasty surprises ie glued railings or overly tight clips.

[irishthump]

On 19/7/2022 at 3:38 PM, Sean said:

Polarity becomes important if double heading 2 or more sound units.

 

In what way is the polarity important?

[Sean]

Taken from ESU manual but also applicable to double heads. if a speaker is wired backwards it moves in the opposite direction and a positive sound wave becomes a negative one. audibly it will sound the same to us as humans however a speaker wired the other way around will be producing a positive sound wave and if both operate together then there is potential for destructive interference to the sound wave before it hits our ears and a good proportion of the sound will be cancelled out. it wont be perfect cancellation either and the sound and level of interference will change greatly as the loco moves around the room. (see recording studio example below for a more controlled scientific breakdown)

Most people tend to run double headers one with sound and one without due to the current cost of decoders which makes this a non issue.

 

In a recording studio, when recording drums, a microphone will be placed on the top and the bottom of the snare. the distance between the microphones and the drum must be the exact same on both sides so that the sound of the strike reaches both micrphones at the same time or you will hear 2 strikes milliseconds apart. the same phenomena occurs here. as the microphones are facing one another they will move in opposite directions and although a loud strike has been recorded it will barely be audible at all on the recording and all that will be heard is the sound of the room i.e. the decay and reverb from the strike.  To fix this we have a button to flip the polarity on each of the inputs. and if we forget to press that, we can always do it  afterwards during editing.

I am not sure how much all of this actually applies to us with model trains but I do know of at least one member on here who was reporting phase issues when attempting to double head with 2 sound decoders.

 

 

 

 

 

[irishthump]

19 hours ago, Sean said:

Taken from ESU manual but also applicable to double heads. if a speaker is wired backwards it moves in the opposite direction and a positive sound wave becomes a negative one. audibly it will sound the same to us as humans however a speaker wired the other way around will be producing a positive sound wave and if both operate together then there is potential for destructive interference to the sound wave before it hits our ears and a good proportion of the sound will be cancelled out. it wont be perfect cancellation either and the sound and level of interference will change greatly as the loco moves around the room. (see recording studio example below for a more controlled scientific breakdown)

Most people tend to run double headers one with sound and one without due to the current cost of decoders which makes this a non issue.

 

In a recording studio, when recording drums, a microphone will be placed on the top and the bottom of the snare. the distance between the microphones and the drum must be the exact same on both sides so that the sound of the strike reaches both micrphones at the same time or you will hear 2 strikes milliseconds apart. the same phenomena occurs here. as the microphones are facing one another they will move in opposite directions and although a loud strike has been recorded it will barely be audible at all on the recording and all that will be heard is the sound of the room i.e. the decay and reverb from the strike.  To fix this we have a button to flip the polarity on each of the inputs. and if we forget to press that, we can always do it  afterwards during editing.

I am not sure how much all of this actually applies to us with model trains but I do know of at least one member on here who was reporting phase issues when attempting to double head with 2 sound decoders.

 

 

 

 

 

When double heading locos that are each fitted with their own decoder the speaker the phasing issue only arises when running identical sound files in both locos. You can easily get around this with Loksound decoders by varying the playback speed function on each sound file.

[Broithe]

For anti-phasing to occur from speakers using two different sources, for more than a very short period, they would also have to start at exactly the same time and continue at exactly the same speed of delivery.

It's easy enough to cause it when setting up speakers on a stereo system, i.e., from one source - my local Dixons shop used to do it all the time. I fixed it for them a few times, but I don't think the lad ever really understood, and I gave up.

From two sources, you can get 'beating', but this will happen in real life anyway. It's usually more noticeable with the the lower frequencies.

 

Anti-phasing is how noise-cancelling headphones work, they listen to the noise and, if it's regular, drive the speaker in the opposite phase by an appropriate amount. I'd always fancied a pair, but I wasn't going to fork out for the Bose ones - then Lidl had them for under a tenner. They were surprisingly good, against a steady noise. Turning them on in the car was almost alarming, as it induced almost total silence, like I'd left the runway...

Edited July 21, 2022 by Broithe