G Scale Loudspeakers

[electricity_bill]

Hello
I am upgrading both my USA Trains F Units and my LGB Queen Mary ALCO to sound using MRC decoders. Does anybody know a source for suitable loudspeakers? The fuel tank mounting in the F unit is about 65mm in diameter and the ALCO body mounting is about 45mm in diameter.
Bill

 

[ntpntpntp]

ebay worked for me last time I needed speakers. Loads to choose from so you can go for whatever will fit the space best (there are various styles/sizes of magnet on the back). Just make sure you get ones with the correct impedance to match what the MRC decoder expects.

 

[Gizzy]

The MRC decoder I fitted had a very small speaker, about 40mm I think?

I replaced it with a larger 8 ohm speaker (That MMTS had taken out of a similar LGB loco he'd converted to battery power) which has proved to be much better.

Massoth speakers can be brought from Dragon for around £10....

 

[electricity_bill]

How did you narrow down your search on ebay? There are 1000s!

 

[ntpntpntp]

Re:G Scale Loudspeakers

How did you narrow down your search on ebay? There are 1000s!

speaker size and impedance would be a good start, so try things like "speaker 65mm 8 ohm" or whatever it is you actually need. Try separate searches using both imperial and metric measurements.

As you say, loads out there so you should be able to find something suitable. Probably best to go for mylar cone rather than paper for better moisture resistance.

 

[Gizzy]

Re:G Scale Loudspeakers

Have a look here Bill....

http://www.dragon-gscale.co.uk/massoth-8241020-loudspeaker-57mm-3193-p.asp

http://www.dragon-gscale.co.uk/massoth-8241030-loudspeaker-70mm-3194-p.asp

 

[Zerogee]

Re:G Scale Loudspeakers

Probably a silly question that I really SHOULD know the answer to, if only I could remember a bit more of my school physics lessons, but I'm asking it to put my mind at rest and get a definitive answer:

Am I right in thinking that the thing that really matters for speaker compatibility is the impedance rating? The WATTAGE of the speaker is just its MAXIMUM handling capability, and as long as this exceeds the output of the sound decoder (or any other device driving the speaker) then it will work OK? So if I have a Massoth decoder which requires an 8ohm speaker and outputs (say) 2 watts, then effectively any 8ohm speaker rated at 2 watts OR MORE will be OK?

Jon.

 

[Gizzy]

Re:G Scale Loudspeakers

Probably a silly question that I really SHOULD know the answer to, if only I could remember a bit more of my school physics lessons, but I'm asking it to put my mind at rest and get a definitive answer:

Am I right in thinking that the thing that really matters for speaker compatibility is the impedance rating? The WATTAGE of the speaker is just its MAXIMUM handling capability, and as long as this exceeds the output of the sound decoder (or any other device driving the speaker) then it will work OK? So if I have a Massoth decoder which requires an 8ohm speaker and outputs (say) 2 watts, then effectively any 8ohm speaker rated at 2 watts OR MORE will be OK?

Jon.

CORRECT!

Have 5 stars and go to the top of the physics class....

 

[Neil Robinson]

Re:G Scale Loudspeakers

As Gizzy has said, higher impedances and power ratings are O.K.
This is true as lower impedances could overload the amplifier and lower power rating may damage the speaker, resulting in damage that may in turn overload the amplifier.
Another characteristic that influences my choice of speaker is speaker efficiency. Not so important as the above as no damage should be caused as a result of a less than optimum choice. However I feel that it's best to be able to get the most out of a sound unit as other considerations such as physical size and enclosure design tend to be restrictive.
If you can view the speaker specifications the efficiency is often quoted in dB per Watt at one meter, the higher the better. Even a small increase can make a difference as dB is a logarithmic unit, doubling in volume for every ten units increase. That is to say increasing from 100dB to 110dB is a 100% increase, not a 10% one!

 

[Zerogee]

Re:G Scale Loudspeakers

Thanks Gizzy and Neil..... so am I correct in understanding that a HIGHER impedance speaker can be used, eg: a Massoth chip requiring an 8ohm speaker could be safely connected to a 16ohm or 32ohm one, but definitely NOT to a 4ohm...?
What is the result of higher impedance - less volume?

Going back to the wattage issue, most of the Massoth sound decoders have output stages rated at either 2 or 3 watts - BUT Massoth themselves offer a small (28mm) round speaker only rated at 1 watt, with no warnings about any compatibility issues. Can I use one of these little speakers in very tight installation situations (eg a Feldbahn 0-4-0) - is it just a case of not turning the volume up too high and overloading it?

Thanks again!

Jon.

 

[Gizzy]

Re:G Scale Loudspeakers

Thanks Gizzy and Neil..... so am I correct in understanding that a HIGHER impedance speaker can be used, eg: a Massoth chip requiring an 8ohm speaker could be safely connected to a 16ohm or 32ohm one, but definitely NOT to a 4ohm...?
What is the result of higher impedance - less volume?

Going back to the wattage issue, most of the Massoth sound decoders have output stages rated at either 2 or 3 watts - BUT Massoth themselves offer a small (28mm) round speaker only rated at 1 watt, with no warnings about any compatibility issues. Can I use one of these little speakers in very tight installation situations (eg a Feldbahn 0-4-0) - is it just a case of not turning the volume up too high and overloading it?

Thanks again!

Jon.

This might help you understand Jon....


http://www.prestonelectronics.com/audio/Impedance.htm

 

[KeithT]

Re:G Scale Loudspeakers

Have look for Visaton speakers. They perform well above many of the competitors.

 

[Zerogee]

Re:G Scale Loudspeakers

Thanks Gizzy and Neil..... so am I correct in understanding that a HIGHER impedance speaker can be used, eg: a Massoth chip requiring an 8ohm speaker could be safely connected to a 16ohm or 32ohm one, but definitely NOT to a 4ohm...?
What is the result of higher impedance - less volume?

Going back to the wattage issue, most of the Massoth sound decoders have output stages rated at either 2 or 3 watts - BUT Massoth themselves offer a small (28mm) round speaker only rated at 1 watt, with no warnings about any compatibility issues. Can I use one of these little speakers in very tight installation situations (eg a Feldbahn 0-4-0) - is it just a case of not turning the volume up too high and overloading it?

Thanks again!

Jon.

This might help you understand Jon....


http://www.prestonelectronics.com/audio/Impedance.htm

Thanks Gizzy, that was a useful reminder of what I should have remembered about the basics!
Following a link from there took me to an even more useful bit about amp and speaker wattages - however it didn't so much answer my question as amplify (pun intended!) my concerns - specifically, it said:

"A properly designed amplifier/speaker system for sound reinforcement will have enough amplifier power that clipping distortion of the amplifier will never occur at any desired volume level, AND speakers that can handle continuous power near the rated output of the amplifier. Using an amplifier with twice the power rating of the speaker (or more) is inviting a trip to the repair shop."

Which just makes me worry a little about using (for example) a standard 2 watt Massoth-supplied speaker with one of their decoders that has a 3 watt output (like the S module)....

Jon.

 

[Zerogee]

Re:G Scale Loudspeakers

Have look for Visaton speakers. They perform well above many of the competitors.

Yep, I've used Massoth-supplied Visaton speakers in several installations already, including putting a honking great 70mm FRS7 into my 2095 BoBo - I swear the speaker weighs almost as much as one of the loco's ballast weights!!

Jon.

 

[Philbahn]

Re:G Scale Loudspeakers

I use Visaton FRS7 15 watt (impact audio) outside Crewe or C P C Farnell seem to have them.
Also don't forget to put a baffle box on the back, I use aerosol caps glued in place. Makes all the difference

 

[Doug]

Re:G Scale Loudspeakers

Running an amp at 2W output will be pretty deafening in a room. So a 1W speaker will be pretty loud, just don't turn the amp up so high.

 

[Martino]

Re:G Scale Loudspeakers

And try some micro fibre packing in the baffle. That really does the trick.

 

[electricity_bill]

Re:G Scale Loudspeakers

My experience is that using an 8ohm speaker with a decoder with a 4 ohm output impedance dramatically reduces volume. I seem to remember the theory that you get maximum power transfer when amplifier output impedance and load impedance match.

 

[electricity_bill]

Re:G Scale Loudspeakers

Good old car boot sale. Two mini speakers 50p. Sorted.