ERR Sound Commander, not that loud

Lou1985 posted:

Any idea what the wattage output is on any of those speakers you listed? I could probably fit that larger "full range" speaker inside the PA's shell easily. 

See for yourself, they have specifications listed.

https://www.parts-express.com/brand/visaton/502

For instance, for a typical one, this is part of the listing.  The green arrow is probably the real rating, the red one is the max power, but I suspect distortion is significant at that power level.

Since my TAS unit gave up and crashed on me, I have planned on putting an ERR system in to replace it.  I have installed several ERR system and they all seem to work well with the supplied speaker.  Now that 3rd Rail seems to have changed some I will go to my spares first.  I think with the electronics in the lead unit I am going to use the tether system for the speaker.  I have used it already for the light in the non powered unit to make it directional.

Currently I have reworked the AA units by painting the trucks silver, and adding dull coat and satin coat paint to the cowling.  I am now waiting for lights to come from Evans designs.  I think the unit looks great and hopefully will sound great with the PA sounds from the ERR units.

gunrunnerjohn posted:

Lou1985 posted:

Any idea what the wattage output is on any of those speakers you listed? I could probably fit that larger "full range" speaker inside the PA's shell easily. 

See for yourself, they have specifications listed.

https://www.parts-express.com/brand/visaton/502

For instance, for a typical one, this is part of the listing.  The green arrow is probably the real rating, the red one is the max power, but I suspect distortion is significant at that power level.

Thanks! I'll look into what I can make fit.

I use an ESU Visaton 41mm X 71mm rectangular speaker that fits in the fuel tank of all of my Atlas locomotives.

It's the same size as the factory installed speaker with the same impedance (8 ohms) and output (2 watts).

I install a 2nd speaker, TDS (formerly QSI) High Bass, that is 28mm diameter. It's also rated at 8 ohms and 2 watts.

Adding a 2nd speaker not only increases volume significantly but gives a richer, fuller sound. It's definitely the way to go.

Two 8 ohm speakers can't be properly matched to the RailSounds boards, you should have either two 4 ohm speakers or two sixteen ohm speakers.

John, Catnaps a 2 railer and ESU decoders run at 4 ohms so his comment doesnt mesh with the thread

Fortunately the Visiton site gives speaker specs. Looking over all the 2"'speakers this one stands out. The FRS-5X. Sensitivity is 86db/watt. Resonant frequency is 190 hz. Rare for a 2" speaker to be below 200 hz and most are 250 or higher. Below that number it begins to roll off. It actually looks very similar to Lionel's 50mm Fatboy though I have no idea if they are the same.

https://www.parts-express.com/...-5x-8-spec-sheet.pdf

Look at the spec sheets and compare frequency response and sensitivity. Lionel/ERR sound boards only put out about 1 watt so any speaker rated at 1 watt or greater will be OK. This one is rated for 5 watts so no worries here.

I may have try a some of these.

Pete

There are many other specs on the Visiton site for each driver. These can be used to determine the ideal enclosure size. For the FRS-5X above. These two graphs show how different enclosures can affect frequency response.

The ideal enclosure would be 23 liters to give an optimally flat response and then roll off gradually. The blue line in these graphs.

Note it is nearly flat to 300 hz but down 10db at 100 hz.

The volume of the enclosure that ERR used to provide is .04 liter. Using it with this speaker gives this response.

Note the peak now at 500 hz but at 100 hz response is down 28 db, barely audible.

Most who use an enclosure like this where none existed before will note an increase in volume, the peak at 500 hz but may not realize the loss of the lower frequencies. Maybe they were never recorded in the sound files. 

Maybe Rudy or Jon Z would comment if frequencies are deliberately cut to save memory or for any other reason.

I used this site to calculate the graphs. Just plug in the numbers.

http://www.micka.de/en/index.php#ideal

Pete

gunrunnerjohn posted:

Two 8 ohm speakers can't be properly matched to the RailSounds boards, you should have either two 4 ohm speakers or two sixteen ohm speakers.

I know there has been a lot of chatter about whether the speaker impedance matching matters for solid state amplfiers like it did for tube amps with a transformer. After some reading and thought on it, I am thinking what matters is the minimum allowable impedance for the solid state amp. What I don't know, is the minimum. So in this case, you're thinking that is 8 ohms for these sound cards. I wonder if say 4 ohms would be louder and not too low a load impedance.

I personally wouldn't push the amplifier on the RS Commander that hard.  While they have it running a 4 ohm load, the power dissipation goes WAY up, over twice what it is for an 8 ohm load.  That tiny chip can't really dissipate well over a watt without significant heatsinking, and it has none.  You're playing with fire running this with a 4 ohm load.

cjack posted:

I know there has been a lot of chatter about whether the speaker impedance matching matters for solid state amplfiers like it did for tube amps with a transformer. After some reading and thought on it, I am thinking what matters is the minimum allowable impedance for the solid state amp. What I don't know, is the minimum. So in this case, you're thinking that is 8 ohms for these sound cards. I wonder if say 4 ohms would be louder and not too low a load impedance.

Yes, it matters.  Look at automotive amps.  They are all SS, and you can blow them up if you try to push a 8 ohm amp at 4 ohms (I used to work at Rockford Fosgate.  Number one killer of amps was impedance mismatch.).  You want to match the RMS of the amp and speaker as well as the impedance.  Also make sure that the max rating of the speaker is pretty close to the max of the amp.  Having a 10 watt speaker on a 2 watt max amp isn't good.  You can damage speakers by under powering them too at loud levels.  An enclosure improves sound for any speaker, and sizing and shape (And porting.) of that enclosure will help you fine tune the sound to your liking.

There is a whole science to speakers, amps, and enclosures.  Sure it doesn't apply as much to us as we don't deal with 30+ watts (A base car setup is in the hundreds.) but we shouldn't just go dismissing it either.  We can get the volume and tone we want out of our little locomotives if we take the time and do it right.

gunrunnerjohn posted:

I personally wouldn't push the amplifier on the RS Commander that hard.  While they have it running a 4 ohm load, the power dissipation goes WAY up, over twice what it is for an 8 ohm load.  That tiny chip can't really dissipate well over a watt without significant heatsinking, and it has none.  You're playing with fire running this with a 4 ohm load.

Good info, thanks.

Lou, acoustic suspension speakers are sealed enclosures much like the small plastic cans most people use in toy trains.  They are never as efficient as vented cabinets such as base reflex or transmission line enclosures. With this puny amp one really needs a vented design. I have not tried to build a BR or TL enclosure  to fit inside a locomotive though I think one could fit inside an unpowered unit. What I do is mount the speaker at the top of a cardboard or plastic tube with the back of the speaker frame against the tube, speaker cone facing UP. I open the speaker holes in the floor of the loco as much as possible even to the point of cutting them entirely out.  One thing not to do if you need more volume is to mount the cone 4-5mm from the tiny holes in the floor of the loco. It's OK to mount it on the floor if you are willing to cut a hole the size of the speaker cone. You must let the cone breath to reach it's full excursion. Even if you are unwilling to cut the hole in the floor of the loco the speaker mounted at the top of the tube giving a 1.5-2" air space between the cone and the sound holes in the floor will add noticeable volume. When Lionel came out with RailSounds 1 in 1989  they used an amp that was far too weak and my quest for more volume prompted me to try dozens of ideas to get more volume and the speaker facing up at the top of a cardboard tube was noticeably louder than any fully closed enclosure I tried.  Sealing the body and any small holes in the floor of your loco may help a bit but not to any great extent that I can tell just by listening.  Most who have heard my modified locos find the volume much too loud including myself so I turn most of them down a bit.

Fully sealed speakers in music and home theater setups became popular when high powered amps became cheaper than shipping large speaker cabinets to the store. The smaller the enclosure the more power you need as well as more equalization (tone control) which again ups the power requirements. A friend of mine has the greatest sub woofers anyone has ever heard, not to mention the rest of his system . Two cabnets approximately two foot square each cabinet with two 16" woofers back to back facing out in a dipole fashion. He is driving each cabinet with a 500 watt amp on each one. He wanted to build the cabinets with twice the interior volume as it would cut the power requirements by 75% for a given sound pressure level.  However his wife would not stand for the larger cabinets so he bought the big amps instead. A sealed speaker cabinet is NOT an echo chamber but rather a spring that the speaker cone reacts against. The smaller the cabinet the stronger the spring and the more power it takes to drive the cone to full excursion against the spring. Your going to need vented enclosures or much larger enclosures with the small ERR amp.   j

gunrunnerjohn posted:

I personally wouldn't push the amplifier on the RS Commander that hard.  While they have it running a 4 ohm load, the power dissipation goes WAY up, over twice what it is for an 8 ohm load.  That tiny chip can't really dissipate well over a watt without significant heatsinking, and it has none.  You're playing with fire running this with a 4 ohm load.

John,  wondering. Do you think if heat sink fins were added to the top of that chip it would make any difference. Not the same as conducting the heat out through a metal lead but still able to move some heat away.  I have some experience in a similar situation with a film scanner.  The Minolta Dimage Scan MultiPro is a high end medium format film scanner long out of production. Many of them died an early death due to the chip (TI- TSB41AB3) that drives the FireWire port dying.   So with no factory provisions to cool the chip when we replaced the chip we also fashioned small copper fins and epoxied them on with JB weld, thinking the metal filled epoxy would conduct heat better than plain epoxy.  The owners who added the fins when installing the new chip have had no failures since adopting the strategy about ten years ago.  I'm convinced it is working to the degree needed for that application.    j

You can certainly add a heatsink with thermal epoxy to increase the dissipation of the amplifier chip, that's a widely used technique in industry.  I even have thermal epoxy for that very purpose.

JohnActon posted:

Lou, acoustic suspension speakers are sealed enclosures much like the small plastic cans most people use in toy trains.  They are never as efficient as vented cabinets such as base reflex or transmission line enclosures. With this puny amp one really needs a vented design. I have not tried to build a BR or TL enclosure  to fit inside a locomotive though I think one could fit inside an unpowered unit.

As was pointed out above, building speaker enclosures is a scientific endeavor. First off not all drivers will work in a ducted port, bass reflex, or transmission line box. Those designs require certain electrical and mechanical driver characteristics. The combination of which are listed as Qt on a spec list that shows the Thiele-Small parameters. That number has be below .65.

Secondly, designs that utilize the speakers back wave have to much larger than a close box design. To augment even a 100 hz wave that box has to have a chamber at least 25 feet long for a quarter wave to return in phase with the front wave.

Laws of physics are going to prevent a high fidelity system using a 2" or smaller driver. The speakers themselves are not capable of any real bass response and any enclosure that would enhance that response will not fit an any O scale piece of motive power or rolling stock.

Best bet is look for a driver with the greatest Sensitivity if greatest volume is your goal.

Pete

I agree that designing a ducted speaker baffle is way beyond the abilities of 99.9% of the folks here, including me, I have seen some amazing examples of very small speakers and baffles with outstanding audio output.  If you look at some of the higher end laptops, they have some amazing technology in the speakers.  I have some that actually do have ports, and they produce surprisingly good sound for such a small speaker, far in excess of what you'd expect.  The arrow points to the port on these.

With ported vs sealed, it also go for the type of music (Sound) you will mostly be playing.  Ported it good for a very specific frequency.  They are also good for a sustained sound.  Sealed have a better over all frequency range, but aren't as load.  They are also excellent for quickly changing sound.  When listening to music I like a sealed sound better over ported.  But with most locomotives' prime movers being about a small freq range a ported would make it louder.  But like said, we just don't have the room to do it right.  But also said, you can greatly improve it with experimentation.  Some is better then none.

But the short of it is, you need a speaker baffle, and you must match impedance of the speaker(s) to the amp.

So to follow this up I ended up coming up with a solution to the volume issue. I moved the RailSounds board from the powered unit to the dummy A unit. Doing this I had room to mount a 8 ohm, 1 watt, 2.25" speaker with a baffle made from a spray paint can lid. Then I marked the location of the speaker and drilled holes in the floor of the dummy unit to let the sound out. This resulted in MUCH improved sound volume. The sound output is now on par with my other factory Railsounds and PS2 locomotives.

Larger speakers typically yield better results, simple sound physics.  Glad you found a solution to your issue.