Smallest Speakers for onboard sound with Loksound V5 Nano?

[ednadolski]

Has anyone used these (or similar) for onboard sound in a diesel (SD40/SD70/Dash9/etc)?    Are there any better options to use w/a Loksound V5 Nano?   Seems these ought to fit in an N scale diesel, but I am thinking at 6mm wide perhaps Z scale could be viable as well  (Probably one would need to mill out the fuel tank area for the decoder).

https://www.mouser.com/datasheet/2/334/AR01532MS-SC15-WP-R-1267018.pdf
https://www.mouser.com/datasheet/2/1628/cmr_12062s_67-3509165.pdf
https://www.mouser.com/datasheet/2/334/AR01232MS-SC12-WP-R-1267043.pdf
https://www.mouser.com/datasheet/2/1628/cmr_15062s_67-3509090.pdf
https://api.puiaudio.com/file/36160c17-2f6d-4aa1-9100-6bb6f149942a.pdf

TIA,
Ed

[GGNInNScale]

Hi  No, not this brand.  I get most of mine from DigiKey, OWS brand, many sizes.  Most of these little drivers have similar designs and similar performance.  Physics dictates how well they can perform, coupled with the effective volume of the back case.  These are like the AR speakers of old.  So called "Infinite baffle"- but there is a lot more to this than can be discussed here.  I started building speakers in about 1968 or so- infinite baffle, ported reflex, horn-loaded, etc.  The details of the respective materials and manufacturing processes (and retailer markup) determines the price(s) of the little speakers. 

[jdcolombo]

The speakers on your list are all rated at 32 ohms impedance.  The ESU LokSound decoders are designed for 4-16 ohm speakers, and a 32-ohm may be a problem for the audio amplifier output. 

I'd personally stick with a 4-16 ohm speaker, rather than take a chance on a 32-ohm.  It might work fine, or it might cause the audio amplifier circuit to fry.

While I don't know of any 15mm x 6mm speakers in the 4-16 ohm range, there are 8x12 and 9x16 speakers made by several different manufacturers (PUI, CUI, Soberton) that work well in N scale diesel installations, AS LONG AS YOU PROVIDE A PROPER SEALED ENCLOSURE.  By "proper," I mean something with an internal volume of about 500 cu. mm or more, which means an enclosure that is 6mm high for a 12x8mm speaker.  But you can play around with the enclosure design to get the appropriate internal volume - for example, if you make the enclosure longer, and offset the speaker to one side, then you can use less thickness.  For example, if you use an enclosure that is 15mm long (by 8mm wide), then you reach 500 cu.mm of internal volume with a 4.5mm-high enclosure (actually, you get 540 cu.mm, which is better than 500).  In general, enclosures with larger internal volume will sound better, up to a point.

John C.

[peteski]

32 ohm impedance will not cause  any damage to the decoder, but the maximum volume it can produce will be low since the amplifier's output stage is designed for current/voltage needed to  drive 4 and 8 ohm speakers.  Low impedance speakers require more amperage at lower voltage, while higher impedance speakers require higher voltage at lower amperage to produce the same sound levels.

Also as john mentioned, the size matters. Same with the air volume of a hermetic sound enclosure (baffle).  That is why home HiFi speaker systems have large drivers and large volume enclosures.  When producing sound waves a small size speaker membrane "cone" cannot move large volume of air like  larger speaker can.

[ednadolski]

The speakers on your list are all rated at 32 ohms impedance.  The ESU LokSound decoders are designed for 4-16 ohm speakers, and a 32-ohm may be a problem for the audio amplifier output.

Per ESU, the Nano can handle 32 ohms:  https://esu.eu/en/products/loksound/loksound-5-nano-dcc/

The LokSound 5 Nano Decoder can play up to 12 channels simultaneously. Each channel can be resolved with up to 16 bits / 31250 kHz and offers hi-fi quality on your system. There is virtually no difference to the original audible anymore. A Class-D audio output with up to 3W output power controls the speakers, which may have between 4 ohms and 32 ohms impedance. A 128 Mbit sound memory provides enough capacity.All individual noises can be adjusted individually in the volume. The super-flexible sound engine without a rigid schedule allows the exemplary simulation of all conceivable rail tracks.

In general, enclosures with larger internal volume will sound better, up to a point.

Also as john mentioned, the size matters. Same with the air volume of a hermetic sound enclosure (baffle).

Granted, It may well turn out that getting any sort of enclosure into a Z-scale diesel is problematic.  I can always resort to my stationary decoder+subwoofer thing if the sound needs more 'filling out'.   Esp. with Z, I suspect the challenge will be more about keeping the sound 'in scale' with the trains and the rest of the modeled scene.

In any event, it seems that these speakers may be technically feasible, while the quality of the sound will have to be determined by trial-and error.  I suspect the decoder's audio output level will need to be set pretty low.

Ed

[peteski]

In any event, it seems that these speakers may be technically feasible, while the quality of the sound will have to be determined by trial-and error.  I suspect the decoder's audio output level will need to be set pretty low.

Actually you will have to crank the decoder's audio volume higher (not lower) than with 4 or 8 ohm speakers to get acceptable volume level.  Since power amp's supply voltage is fixed, the speakers impedance (resistance) determines how much power will be available from the audio amp. As you said, experimenting will show what is possible.

[jdcolombo]

Per ESU, the Nano can handle 32 ohms:  https://esu.eu/en/products/loksound/loksound-5-nano-dcc/

Ed

Ah.  That's interesting.  I didn't know the Nano was designed to work with 32 ohms. The specs on that 15 x 6mm PUI look pretty good . . .

John C.

[peteski]

All the LokSound 5 decoders support speakers with 4-32 ohm impedance.

[GGNInNScale]

The speakers on your list are all rated at 32 ohms impedance.  The ESU LokSound decoders are designed for 4-16 ohm speakers, and a 32-ohm may be a problem for the audio amplifier output. 

I'd personally stick with a 4-16 ohm speaker, rather than take a chance on a 32-ohm.  It might work fine, or it might cause the audio amplifier circuit to fry.

While I don't know of any 15mm x 6mm speakers in the 4-16 ohm range, there are 8x12 and 9x16 speakers made by several different manufacturers (PUI, CUI, Soberton) that work well in N scale diesel installations, AS LONG AS YOU PROVIDE A PROPER SEALED ENCLOSURE.  By "proper," I mean something with an internal volume of about 500 cu. mm or more, which means an enclosure that is 6mm high for a 12x8mm speaker.  But you can play around with the enclosure design to get the appropriate internal volume - for example, if you make the enclosure longer, and offset the speaker to one side, then you can use less thickness.  For example, if you use an enclosure that is 15mm long (by 8mm wide), then you reach 500 cu.mm of internal volume with a 4.5mm-high enclosure (actually, you get 540 cu.mm, which is better than 500).  In general, enclosures with larger internal volume will sound better, up to a point.

John C.

  32Ohms will not hurt the decoder.  It will simply reduce the current, hence the apparent volume will be lower.  The current is Voltage/Resistance.  Thus, with the maximum drive voltage fixed by the decoder sound circuit, independent of the speaker impedance, the current demand will be less in the "32Ohm" case.  Power (approximation) is I^2 * R, so with the reduced current, there will be less sound energy radiated from the speaker.

[GGNInNScale]

I should have posted:  "The lowest resistance (impedance) is the key issue.  4 Ohms is a tough load.  Any speaker with a HIGHER impedance is fine, just the sound level will be reduced with higher impedance."  The other thing is that the amplifiers in the decoders are mostly running "Class D" (very efficient design), which is a switching-type amplifier that can handle the lower impedance.

[milw156]

Given that the sound levels produced by most decoders are too loud to begin with, and we end up decreasing the max volume anyway, is an impedance of 32 ohms really an issue?
Rick

[peteski]

Given that the sound levels produced by most decoders are too loud to begin with, and we end up decreasing the max volume anyway, is an impedance of 32 ohms really an issue?
Rick

Well, that is a matter of the environment where the model runs, and also personal taste.  Most N scale locos are barely audible when running on a layout during model RR shows. It is always good to have the extra volume available when needed.

[milw156]

agreed! I find myself upping CV63 when at shows so I can hear the thing, might end up using the "mute" functionality so I can toggle between show volume, home layout volume,  or quiet.

[GGNInNScale]

I have found that I have turned down the sound level(s) and re-balanced the relative levels of the horns, bells and engine sounds.  When I first started with sound I had CV63 pretty high.  Now after several years most of my diesels are running at CV63 less than 100.  An increase of CV196 helps a bit on the lower end of the sound.  I find that CV197 can make the sound a bit shrill to my ears, so I tend to decrease this value.