MTH 5v PS2.0 speaker replacement

giver me the item number of the engine, engine's in question, so i can look up the part numbers!

Alan

It's a 16-ohm speaker which is a bit problematic. I've been investigating using pairs of 8-ohm H.O. speakers in series as replacements. Some of them are pretty small and could possibly be squeezed into the space in the fuel tanks.

Do you have a source you're look at for these? That might be an option.

Alan,

I can work up a list, was hoping there was a one-size fits all solution to this issue, but perhaps not.

Here is a link to another thread and post by Dale H. It lists some suppliers of speakers. I don't know if they have the appropriate 16 ohm speakers, but something to look at.

Speaker sources

I looked at the above links and didn't find much, mostly 4 & 8 ohm. Here is one from Amazon 2"-16 ohm full range speaker Maybe someone will comment on it's usability for train sounds.

Why not buy them from MTH?

They usually have them in stock!

Living in Florida with the high humidity I find the paper speakers to fail far to often.......  here is a good replacement for the 2 inch size common to many MTH engines,  not all unfortunately as it works very well. 

Amazon link,  buy them in volume and they are pretty cheap,  less than $4 each:  http://www.amazon.com/dp/B00IK...oliid=I13ZJ3N9TPZHU8

Ohms at this size and wattage output does not matter at all.........  

Polypropylene (plastic) design has held up much longer than the paper,  been using these for 3 years now.  No more failures.........

Looks like the same VECO being discussed in the previos thread provided.....

Mark

Pat,

It might come to that, but the last round of parts I bought from MTH was three tiny plastic joiners for the spine cars, which break if one looks at them wrong (design failure) and it set me back $30.00. So I've been more than a little displeased with buying parts from MTH. Their service is great, but their prices not so much.

Just thought if there was a non-branded option it would be worth looking into.

Thanks Mark --

Much appreciated, the never dry Keys environment killed more than a few trains, before they were all resettled in Cincinnati.

JW

I was looking at Railmaster Hobbies in Bellflower, CA and Tony's Train Exchange. Both are DCC suppliers. The problem is the wattage. Most are only 1 or 2 watts.

Railmaster's Speaker Page: http://www.railmasterhobbies.com/Speakers.htm

Tony's Speaker Page: http://www.tonystrains.com/ (Site is down for maintenance)

Matt,

What wattage do the MTH speakers need to be, 4 watts?

The typical one is 3 watts, but I've seen 2 watt ones as well.

Your flaking speakers were the STAR 16 ohm 5 W speakers, They have been replaced by a different manufacture version.  It is BF-0000033 which was the original part number.  It is a 50mm x 17mm 16ohm 5W.

The PS-2 5V boards had a health audio amp and you can see .5amp fluctuations on a Z-4000 meter when sounds start up and whistle blowing.  Having said that many early engines used a .5W speaker, especially RTR.

16 ohm has become a much harder to get speaker, and I would not lower the ohms and hope it works.

I also have looked, and they are not available in the 5W or even 3 or 4 W version.  Maybe a direct buy from China with a higher minimum count, but even ebay doesn't show any other than one which is a little taller and lower watt rating.

You do want to check dia, at least a few models with Vanderbilt tenders used a 45mm speaker and even MTH does't have a replacement for that one.   G

What is the wattage rating of an MTH power amplifier? That will determine the minimum wattage rating required of a speaker. Using a speaker with a higher wattage rating than required might help it last longer but won't necessarly improve the frequency response or volume and may in fact reduce the volume.

Pete

I believe the amplifier was 3 watt!

Alan

The PS/3 amplifier is a WM9081 2.6 watt class AB/D amplifier.

The 3V PS/2 amplifier is a TPA2000D1 2 watt class D audio amplifier.

The 5V PS/2 amplifier is a TDA7056A 3 watt audio amplifier.

It is also worthy to note the sound file had the ability to control the db output.  There was at least 1 5V sound file that they had to rewrite to half the volume during start up because the audio was overloading the 5V power supply at startup.

Watching the meters on a PS-2 5V engine starting up is quite a treat, which also may have contributed to component failures over time.  It draws some current! 

I imagine sound files that limit output may have allowed some of the smaller wattage speakers to be used.   G

G, how many of the 5V audio chips have you had to replace? The data sheet for the TDA7065A indicates its has short circuit protection. This may expain why I was able to use a 4 ohm speaker with no apparent damage despite 30 minutes of run time.

This combo gave the best sound of any MTH engine I have heard rivaling the best Legacy engines.

Pete

I've replaced a couple of the 5V amps, I think they die because they get connected to frame ground, I know that's how one of them was killed.  They're obsolete parts, but I still have a few, and I expect that's a lifetime supply as the 5V boards drop there are less of them that will ever need amplifiers.

I have done around 30 or so.  4 sounds pretty low.  I saw an engine or two with 8 ohm.  G

Today, one of the engines with the above mentioned STAR 16ohm speakers got real quite, not no sound, just very low volume. I turned it off instantly to avoid any board damage.

Not good news. Any ideas on where I can find a replacement 50mm, 16ohm, 5watt more or less speaker to replace this on?

Thanks guys!

Best,

Jason

I have a number of those speakers removed from 5V swap-outs, you can have one for the cost of shipping.  Just email me your address to my profile email.

On the TDA7056A is that 3 watts into a 16-ohm load? Back when dinosaurs roamed the earth, a lot of audio amps listed two separate wattage ratings -- one for 4-ohm speakers and another for 8-ohm speakers. Of course the higher wattage rating under the 4-ohm load was the one used in the advertising.

Matt, it is indeed 3w into 16 ohms and 5.2w into 8 ohms with a 12v supply. It implies an 8 ohm speaker would be OK. John or George what is the supply voltage to these amps. The specs say it will work on 4.5 to 18 volts.

Pete

Thanks. 8-ohm speakers are a lot easier to obtain with more options. I have a couple of 5-volt locomotives with speakers that are going.

Here is a link to the spec sheet for the TDA7056A.

http://www.farnell.com/datasheets/809106.pdf

Hi john do you have the digikey part numbers for the ps2 3volt ps2 5 volt and ps3 amplifier ic part numbers. i looked up the one you listed for the ps3 amp and can't find a cross reference?

alan

PS/2 3V Audio Amp: TPA2000D1

PS/2 5V Audio Amp: TDA7056A

PS/3 Audio Output Amp: WM8081

Your assuming your controlling the input power and your not.  MTH designed the board to use 16 ohms.  So your going in the unsafe direction.

Early on speakers where only .5W and then they were upped to 5W.

Take you engine with smoke off on a test track and monitor current while operating the whistle and such on 5V engines.  Some draw a very hefty current.

In fact one engine, they had to program the start up sounds at reduced DB because it overloaded the 5V power supply during startup sequence.

Running 8ohms puts you at risk, because your not limiting the input signal.  Unless you crank the volume way down.   G

G, thats why I asked about the power supply. I figured it may be the weak link if the amplifier is in fact OK with 8 ohms. 

So these are called 5V boards. Does this mean there is one 5V supply for all the circuits? The audio amp is rated at 3 watts into 16 ohms with a 12 V supply. With only a 5v supply its power output would be considerably less. I would think there might be multiple power supply voltages using DC-DC convertors or optionally some regulated and some not regulated depending on track voltages.

Having never been to MTH training I don't have the luxury of schematics.

Pete

I'm sure that MTH gave due consideration to the loading on the amplifier when they designed the board, I'm sure the selection of the 16 ohm speaker wasn't by chance.

FWIW, I have a little sound module I'm working on that's rated to use speakers down to four ohms.  The difference between four ohms and eight ohms is an extra 60% current draw.  Of course, the sound is also considerably louder, that you would expect.

No one has schematics of the boards.  Just observations of what we see on the board and any backward engineering done.

Regardless, in the PS-2 design you have filtered Positive Voltage from the Main rectifier that can be upwards of 24VDC with 18-20VAC input, and then you have a 5VDC regulated power supply.

I am no audio genius, but my understanding would be that the amplifier is put into a circuit design based on its ratings.  While it can work with 8 or 16 ohms, the circuit would be different.  Unfortunately you cannot change the circuit and the software programming of the design.  So just swapping to a 8 ohm speaker could prove hazardous to the amp and the overall PS-2 board especially if done on an engine where the sound file really drives the output of the audio amp.  Shays/Climax, and some diesels come to mind.  They drive high currents during startup sounds and whistle blowing.   G

Would it be a problem using 16 ohm speakers in Proto 1,2 and 3 systems?

It won't hurt the later systems that use 4 ohm speakers, but it won't be as loud.  I've tried the 16 ohm speaker on PS/2 3V and PS/3, other than the reduced volume, it seemed fine.

Why would you try that?  I have had to use original 8 ohm on some Other manufacturer engines that were PS-2 upgraded, but never used a 16 ohm, that is a heavy DB in the wrong direction for good sounds. 

Why would I do that?  Curiosity.  I didn't leave it, I just wanted to see how much difference the sound level would be with the 16 ohm vs. the 4 ohm.