Matching sound to speed

[JWRStation]

Probably already in here but my word searches cannot find it.  So, is it possible to match the TTS sound to actual speed???  I have a number of A4 loco's, modern TTS fitted and also older tender driven models.  My older Guillimot has been fitted with the A4 TTS however, relative to the modern DCC TTS machines the older Guillimot seems to be about twice as fast for the 'same' speed sound...  Can this be adjusted??

Joe

[Chrissaf]

Chuff rates on Steam locos using TTS decoders has come up on the forum many times. Based upon previous answers from those in the know .... there is no adjustment capability in the cheap TTS sound decoders.

[96RAF]

Chris is right. There is no user synchronising adjustment. The chuff matching is done at the design stage at Hornby. BEMF is used to control when the chuff kicks in or coasts, but the actual number of chuffs per wheel rotatation is set and is at best a compromise for several reasons.

 

There can be as many as 18 separate chuff sound grabs, which are spliced together to play in sequence as throttle is applied and BEMF from the motor tells the decoder what rate the loco is going at and if under load or coasting.

 

You can test this by setting the loco going at any speed, then selecting F1 to light the sound up, which will kick in appropriate to the loco speed. If you listen carefully to the chuffs as you increase speed you will hear it is in distinct brackets, not infinitely progressive, so there will always be a point where the chuffs should match and another where they are disparate. Back off the throttle and the chuff will change to coast until the speed matches the throttle and the loco takes the strain again when chuffs will recommence.

 

Diesel sound is much easier to handle as it is recorded in notches and plays as such just like the real thing. Nor do diesels have spokes to watch so it is impossible to find any synchronising fault. You can also notch up a diesel at rest unlike a steam loco.

[JWRStation]

Thanks and I was 90% certain that is the case...It is not to match the chuff to rotation just the number of chuffs!!!  At the moment it is about one per rotation but for a twin should be two so it is noticable that the loco is going twice as fast as the others for the sound that it is eminating..  Problem with Tender drive machines as they do seem to 'hoof' it around the track for the same (DC) setting that makes more modern machines look just right..

[ColinB]

 I am amazed you got TTS to work on an old tender driven loco. The ringfield usually takes in excess of what the TTS can provide, so it keeps resetting. I tried using a class 66 one on an old Lima class 66 loco and it was terrible. 

[Howbi]

 At the moment it is about one per rotation but for a twin should be two

A 2 cylinder loco chuffs 4 times per revolution, each cylinder has twin chambers so chuffs twice and as the 2 cylinders are offset 90 degrees you hear the 4 chuffs but unfortunately TTS does not have this capability........I now only buy steam sound decoders with adjustable CV chuff rates........HB