Broadway Limited T1 Speaker Transplant

[jdcolombo]

Hi everyone.

Yesterday a friend of mine brought over his two BLI T1's to run on my layout.  The engines run superbly, and pulled both an 11-car Kato passenger consist and 40 freight cars without a hint of slipping on my flat-as-a-board NKP layout.  But I wasn't happy with the sound - to me, the sound was far too "tinny" for such a marvelous looking and running engine.  And the balance of the various sounds is awful.  From the factory, the horn is barely audible above the chuffs, and the bell is way too loud - along with the dynamo, which was REALLY annoying. 

So my friend left me one of his T1's to experiment with.  The first thing I did was alter the volume levels of the horn, bell, chuffs and associate steam sounds to get them in better balance.  Fortunately, the Paragon 3 decoder is simpler to program than the Paragon 2, and this didn't take long with the list of CV's (from BLI's web site) in front of me.  Everything comes from the factory set at 128 out of 255; I set the horn at 230; turned down the bell to 60; turned the dynamo down to 30 and turned down everything else (chuffs, background steam hiss; etc.) to 80.  These changes improved things considerably, but the sound was still "thin" to my ears.

So next I took off the tender shell, and found that a speaker replacement would be quite simple.  It turns out that the Paragon 3 decoder, unlike the Paragon 2, uses stock 8-ohm speakers.  So all I had to do was cut off the old speaker, replace it with a 13x18mm cell phone type in a custom enclosure, and glue the rear light LED to the back of that enclosure.  I'll let you all judge the results:

If you are interested in doing this yourself, it's really pretty simple.  Step 1 is to remove the tender shell.  You do this by unscrewing four screws: two at the very back, and two that are about a quarter of the way along the front truck (you'll have to swivel the truck to get to these).  However, when you are finished taking the screws out, the shell won't come off; it's a tight fit, and so you will need to "lever" it loose.  I did this by first sticking a hobby knife blade between the rear end of the shell and the tender floor, then once I created some space, used a screwdriver to lever the rear of the shell up.  Once the rear part of the shell is up about 1/4", you can pull the rear up and then pull off the front end.  This is what you will see inside:

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The speaker is at the far right.  To remove it, you'll need to take out two screws in the back and one in the front.  The front screw is hidden by the connector at the back of the decoder, so you'll need to take out the two screws holding the decoder in for access to the front speaker screw.  When you have the speaker out, replace the decoder screws.

Why this speaker doesn't sound good is something of a mystery.  The speaker itself is a pretty large oval, and it is inside a pretty large enclosure.  But the enclosure really isn't fully sealed (the back is taped on), the speaker itself is mounted inside the enclosure with a foam tape surround, instead of something like glue or silicone; and the speaker fires down into openings in the enclosure which are right up against the tender floor (which itself has no openings). Here's what it looks like taken apart:

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All of this is rather odd, and the speaker itself may not be all that great.  In any event, I decided to replace the whole thing with a 13x18mm cell-phone type speaker in a custom enclosure.  The enclosure sides are 9mm-wide .030 styrene and the bottom is .030 styrene, making the overall height about 10mm.  And I mounted it so that the speaker fires up into the tender shell, to take advantage of the shell creating a sort of reverb chamber (which is particularly noticeable on the horn, IMHO).  For the rear light, I just glued the small piece of circuit board with the rear LED onto the back of the new enclosure, and taped the wires to the sides.

Here are photos of the final installation:

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The whole process took about 30 minutes, including the time I spent making the speaker enclosure.  It's really a pretty simple substitution, and I think produces a worthwhile improvement in the sound. 

This is a great running and pulling engine.  But honestly - if BLI would have taken a bit more care regarding a speaker, it would sound a thousand times better.  And if taking a bit more care meant the thing cost $5 more, who cares?  Is anyone going to complain about $5 on a $300 loco?  C'mon man! (as the ESPN folks would say).  Manufacturers, if you are going to do sound, DO IT RIGHT, particularly in a steam loco tender where you've got enough space to put in a Space X rocket (relatively speaking . . . ).

John C.

[Chris333]

No holes in the floor from factory is strange.

[Point353]

So next I took off the tender shell, and found that a speaker replacement would be quite simple.  So all I had to do was cut off the old speaker, replace it with a 13x18mm cell phone type in a custom enclosure, and glue the rear light LED to the back of that enclosure. 

What is the inside width of the tender shell?

[peteski]

Super write up John!  I was planning on doing this and you saved me bunch of research. Thanks!  The chuffs with the stock setup sound terrible!  Like someone hitting a metal bucket full of ball bearings.

[jdcolombo]

What is the inside width of the tender shell?

I didn't measure it, but it is around 15 mm.  My 13x18 speaker with a .030 styrene box (.030 = approximately .75mm) just fit inside the tender floor rails with a tiny bit of wiggle room.  So I'd estimate 15mm (13 + 1.5 for the two box sides = 14.5).

The stock speaker enclosure is 40mm long, but it has rounded ends.  If you are using a square box, I wouldn't go past 35mm in length, because you need to clear the plastic posts in the tender shell that the screws attach to.

John C.

[Cajonpassfan]

Great write up John, what a difference, thank you!
The weird BLI "ohmage" has always been a problem. So how did you determine the Paragon 3 drives an 8 ohm speaker? Is it on their website somewhere? I looked before and didn't see anything...
Presumably, this would allow the Paragon 3 Diesel boards to be married to sugar cubes as well. (I actually like the Paragon 3 sound generator with its variety of ancillary sounds; it's the speaker/enclosures I find lacking).
Otto

[jdcolombo]

Great write up John, what a difference, thank you!
The weird BLI "ohmage" has always been a problem. So how did you determine the Paragon 3 drives an 8 ohm speaker? Is it on their website somewhere? I looked before and didn't see anything...
Presumably, this would allow the Paragon 3 Diesel boards to be married to sugar cubes as well. (I actually like the Paragon 3 sound generator with its variety of ancillary sounds; it's the speaker/enclosures I find lacking).
Otto

Hi Otto.

I cleaned off the back of the stock speaker, and found it was marked "CTI, 8 Ohms".  I don't know who/what CTI is, but the "8 ohms" was a revelation!

John

[peteski]

Hi Otto.

I cleaned off the back of the stock speaker, and found it was marked "CTI, 8 Ohms".  I don't know who/what CTI is, but the "8 ohms" was a revelation!

John

CTI? It seems that I have seen that name before. It is probably manufacturer's name.

[jdcolombo]

CTI? It seems that I have seen that name before. It is probably manufacturer's name.

Yes, I'm sure it's the manufacturer.  Haven't run into them before.  Soberton, CUI, PUI are the ones I've used since Knowles discontinued production.

John C.

[daniel_leavitt2000]

That's an improvement, for sure. Are all Paragon 3 decoders rated at 8 ohms? What about Paragon 2?

[jdcolombo]

That's an improvement, for sure. Are all Paragon 3 decoders rated at 8 ohms? What about Paragon 2?

Well, all I know for certain is that the speakers in my BLI PA-1's, which had Paragon 2 decoders (until I replaced them with ESU LokSound) were marked 50 ohms.  Many others reported seeing speakers marked 50 ohms in Paragon 2 installations.

The T1, on the other hand, has the new Paragon 3, and the speaker in the T1 was marked 8 ohms.  So I suspect that the Paragon 3's audio amp circuit is new, and works with 8 ohm speakers.  That would make sense - 8 ohm speakers are ubiquitous and made by a variety of suppliers.  50-ohms is a specialized product you'll never see on Digikey or Mouser or other supplier sites.  And all the "single-chip" audio amps I've seen on the electronics supply sites are rated at 4-16 ohm output.

ESU's old LokSound 3.5 used 100 ohm speakers; when they redesigned the LokSound to V.4 several years ago (and the Select), they went to an 8-ohm design.  Looks to me like BLI joined the crowd.

John C.

[Point353]

I didn't measure it, but it is around 15 mm.  My 13x18 speaker with a .030 styrene box (.030 = approximately .75mm) just fit inside the tender floor rails with a tiny bit of wiggle room.  So I'd estimate 15mm (13 + 1.5 for the two box sides = 14.5).

The stock speaker enclosure is 40mm long, but it has rounded ends.  If you are using a square box, I wouldn't go past 35mm in length, because you need to clear the plastic posts in the tender shell that the screws attach to.

Is there sufficient space (between the plastic posts and the circuit board) to accommodate a pair of those 13x18 speakers?

[Cajonpassfan]

Hi Otto.

I cleaned off the back of the stock speaker, and found it was marked "CTI, 8 Ohms".  I don't know who/what CTI is, but the "8 ohms" was a revelation!

John

Yes, quite! Thanks, John.
You would think BLI would note that somewhere. If they did, I can't find it.
I need to look into my diesel Paragon 3's...
Otto

[wazzou]

Replacement sound is excellent.  Nice job John.

[garethashenden]

I didn’t expect to really hear that much of an different in the video. I tend to miss a lot of sutble audio things that other people pick up on. But wow! The difference is really impressive.