retro fit digital sound.

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gromit54
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retro fit digital sound.

Postby gromit54 » Mon Oct 04, 2010 8:56 pm

Just been looking at my class 37's and class 40's and was wondering how easy it is to fit sound to then. Any body out their tried it and are their kits you can get or are you best getting factory fit locos?
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piemanlarger
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Re: retro fit digital sound.

Postby piemanlarger » Thu Oct 07, 2010 1:09 am

done many class 37 but not a 40. presume you mean bachmann

http://www.youtube.com/watch?v=mj_qRg3_Uhc
A loco with no sound chip? Might as well be unpainted!
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gromit54
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Re: retro fit digital sound.

Postby gromit54 » Sat Oct 09, 2010 10:05 am

yes, all bachmann. :)
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gppsoftware
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Re: retro fit digital sound.

Postby gppsoftware » Tue Oct 12, 2010 4:02 am

gromit54 wrote:Just been looking at my class 37's and class 40's and was wondering how easy it is to fit sound to then. Any body out their tried it and are their kits you can get or are you best getting factory fit locos?


I did mine like this: http://www.mrol.com.au/Articles/DCC%20Sound/DCCSoundClass37.aspx

Graham Plowman

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piemanlarger
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Re: retro fit digital sound.

Postby piemanlarger » Tue Oct 12, 2010 8:15 am

With all due respect graham, fitting a speaker without the sound chamber / baffle box will produce far poorer sounds.

I think the best option with the backmann 37 iseither 2 x 23 ml speakers plus the sound boxes locted int he Fuel tanks, or a single Base reflex plus a 20 x 40 under the fan.

I have posts somewhere on how its done, but I think they are on RMWEB?
A loco with no sound chip? Might as well be unpainted!
EWS sound loco depot viewtopic.php?f=22&t=7263
Olivers Road RMD viewtopic.php?f=22&t=18867&start=30

gppsoftware
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Re: retro fit digital sound.

Postby gppsoftware » Tue Oct 12, 2010 10:26 am

piemanlarger wrote:With all due respect graham, fitting a speaker without the sound chamber / baffle box will produce far poorer sounds.

I think the best option with the backmann 37 iseither 2 x 23 ml speakers plus the sound boxes locted int he Fuel tanks, or a single Base reflex plus a 20 x 40 under the fan.

I have posts somewhere on how its done, but I think they are on RMWEB?


Unfortunately, there is great misunderstanding about the use of speakers and unfortunately, this is commonly perpetuated in erroneous myths!

The use of two identical speaker will NEVER gain anything except perhaps, increased volume. It does NOT improve sound quality. So you are wrong on that part.

The second part you are correct on: The ONLY way you will get "better" sound quality is by having two DIFFERENT speakers such as a 23mm and a bass reflex because the two speakers handle different frequency responses. Why do you think that all car stereo and hi-fi systems have multiple different sized speakers in their speaker units ? It is exactly for that reason: that each speaker responds to different sound frequencies, thereby giving a breadth of frequencies, improving sound quality. Quality also has a number of other parameters relating to the amp and as you say, sound chambers and mountings.

The particular loco in the video was actually done a long time ago and it is also one of the versions prior to Bachmann creating space for a speaker. It does indead have a bass reflex in it now, however, I always take a pragmatic view on this: different locos make different sounds. Some have a lot of lower (bass) frequencies while others have a lot of higher frequencies. You have to be selective on the speakers chosen: if a bass reflex is used on a loco with high frequencies, it may not make much difference. Conversely, a loco with low frequencies will loose sound if a bass reflex is not used.

The SWD 37 recording mostly has high frequencies, although a bass reflex does improve things. You can't assume this on all locos though, for example, the SWD class 50 works very well with a single 20 x 40 in a box under the fan.

Graham Plowman

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piemanlarger
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Re: retro fit digital sound.

Postby piemanlarger » Tue Oct 12, 2010 10:36 am

gppsoftware wrote:
Unfortunately, there is great misunderstanding about the use of speakers and unfortunately, this is commonly perpetuated in erroneous myths!

The use of two identical speaker will NEVER gain anything except perhaps, increased volume. It does NOT improve sound quality. So you are wrong on that part.

Graham Plowman



We shall have to agree to differ then. :D
A loco with no sound chip? Might as well be unpainted!
EWS sound loco depot viewtopic.php?f=22&t=7263
Olivers Road RMD viewtopic.php?f=22&t=18867&start=30

gppsoftware
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Re: retro fit digital sound.

Postby gppsoftware » Tue Oct 12, 2010 11:41 am

piemanlarger wrote:
gppsoftware wrote:
Unfortunately, there is great misunderstanding about the use of speakers and unfortunately, this is commonly perpetuated in erroneous myths!

The use of two identical speaker will NEVER gain anything except perhaps, increased volume. It does NOT improve sound quality. So you are wrong on that part.

Graham Plowman



We shall have to agree to differ then. :D


That's up to you. Evidently, you've been indoctrinated with incorrect information from RMWeb where no-one is allowed to correct misunderstandings and consequently, erroneous myths perpetuate!
There's no point in arguing because if you were right, we would find every car stereo and hi-fi manufacturer producing speaker cabinets containing multiple identical speakers. The reason we do not is because this does not give best sound quality because it results in a single range of sound frequencies being handled. The only way you will get better sound quality is by having multiple different speaker sizes all handling different frequency ranges - exactly what all hi-fi does.

Our DCC sound is no different: multiple different speakers is the way to get best sound, notwithstanding the need for baffle boxes and mountings.

I suggest you try taking your argument for multiple identical speakers to any online hi-fi forum or to any hi-fi professional and see how far you get!

Graham Plowman

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piemanlarger
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Re: retro fit digital sound.

Postby piemanlarger » Tue Oct 12, 2010 3:58 pm

gppsoftware wrote:
piemanlarger wrote:
gppsoftware wrote:
Unfortunately, there is great misunderstanding about the use of speakers and unfortunately, this is commonly perpetuated in erroneous myths!

The use of two identical speaker will NEVER gain anything except perhaps, increased volume. It does NOT improve sound quality. So you are wrong on that part.

Graham Plowman




I suggest you try taking your argument for multiple identical speakers to any online hi-fi forum or to any hi-fi professional and see how far you get!

Graham Plowman



No need, they come to exhibitions with me and have been doing so for several years now, where in at least 9 out of 10 occasions, twin 23 ml speakers in the tanks has been the prefered output on class 37 compared to the 37 i fitted with base reflex!
A loco with no sound chip? Might as well be unpainted!
EWS sound loco depot viewtopic.php?f=22&t=7263
Olivers Road RMD viewtopic.php?f=22&t=18867&start=30

Martin71
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Re: retro fit digital sound.

Postby Martin71 » Tue Oct 12, 2010 6:14 pm

Hi

I 100% agree with piemanlarger on the following:

With all due respect graham, fitting a speaker without the sound chamber / baffle box will produce far poorer sounds.


I have done a few sound installs and I would never consider putting in a speaker without a fully sealed housing.

That's up to you. Evidently, you've been indoctrinated with incorrect information from RMWeb where no-one is allowed to correct misunderstandings and consequently, erroneous myths perpetuate!


Graham the link to your website shows a neat install of a loksound. Thats good and nicely done but its not correct, see above. In this case you are the one putting out incorrect information. I would prefer if you didnt post links to your website that provide incorrect info.

The use of two identical speaker will NEVER gain anything except perhaps, increased volume. It does NOT improve sound quality. So you are wrong on that part.

Graham thats not correct their is a special technique you can use with 2 of the same speakers in parallel which will give you at least another 6dB and you will get a slightly broader frequency range.

We can argue whats right and what wrong but I know for sure that if you add a sealed box your sound will greatly improve.

Cheers

Martin

gppsoftware
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Re: retro fit digital sound.

Postby gppsoftware » Wed Oct 13, 2010 12:13 am

Guys (pieman, martin),

As I said in my previous message, the installation I showed was a very old one and has been changed to have baffle boxes and a bass reflex - yes, the article does need updating.
The issue of speakers and sealed sound chambers/baffle boxes is not at issue. I certainly agree that their provision will improve sound quality (although my Hymek actually sounds more reallistic without one than with, which is against my own rule of having them). We are in agreement on that one and don't need to discuss further.

Where we are not in agreement and where I picked up on pieman is the provision of two identical speakers improving sound quality.

This comes down to basic high school wave theory in physics. Let me do my best to explain.

A speaker is manufactured to respond to and render a range of sound frequencies. This range does not normally cover the entire audible sound frequency range. If you want to improve sound quality, then you need to extend the frequency range (a baffle box prevents distortion and reverberation caused by sound waves from the front of the speaker meeting those from the back - see http://en.wikipedia.org/wiki/Loudspeaker_enclosure for more info). To increase the frequency range, you need an extra speaker which is manufactured to respond and render the required frequency range. That is why people add a bass-reflex speaker to the standard ESU speaker - the latter is manufactured to handle higher frequencies and the former is manufactured to handle lower frequencies. When you put the two together, you get better quality sound because you have a better range of frequencies covered.
In evidence of this, I present the Howes class 52 and 42: if you use a standard ESU speaker, you will get sound, bit it is rather 'tinny' because it is lacking the bass tones. If you add a bass-reflex speaker, the bass tones are suddenly audible and in actual fact, there is a whole range of humming noises, fans, pumps etc which you cannot hear with just the standard speaker. Once the bass-reflex is fitted, you can hear them.
So what I am saying is that a single speaker type will only give you a limited range of frequency coverage, normally cutting off the lower bass-tones and killing sound quality.

The reason why the use of two identical speakers will NEVER give better quality sound comes back to our high-school physics lessons.
Two identical speakers will output identical sound waves at identical frequencies. If they are wired in phase so that the peaks and troughs of the sound waves are in sync (ie at the same time - martin calls this 'a special technique'), the effect is that the amplitutude of the sound waves produced by the two speakers is added together (ie the amplitude is double). Doubled wave amplitude to the listener is observed as increased volume, which martin indicated as an extra 6db.
Decibels are a logarithimic measurement of wave 'loadness' and 'sound pressure', usually at a certain frequency ie 'volume' in our space. It is not a measure of 'quality' or frequency range. You will never get greater sound quality or frequency responses from a speaker that isn't designed to render them, no matter how many of them you use! Adding identical speakers does not increase the frequency range. It just increases the amplitude.
Increased wave amplitude is not increased sound quality. Increased sound quality is achieved by a greater range of frequencies - quite different to amplitude.
I think we may have different understandings on what we as individuals consider to be 'better sound quality'. From his comments, it appears that martin, like most people, considers 'better sound quality' to be 'increased volume' but this is incorrect. For example, if identical speakers were used in the Howes 52 and 42 above, they would produce higher volume, but we would still get a 'tinny' result and we still wouldn't hear all those bass tone hum noises - effectively, we've lost a proportion of the sound recording because we've cut off a whole load of frequencies - a loss in sound 'quality'. Add a different speaker type (bass reflex) to extend the frequency response range and you get all the hum noises and the sound is no longer 'tinny' because there are bass tones as well.

All of the above is why car stereo and hi-fi manufacturers install a variety of different sizes of speakers in their speaker cabinets.
The fact that they don't use identical speakers (ie supporting your argument), I would have thought would be enough evidence to prove my case.

A few years ago, when working for an airline client, I had a hearing test using a highly sophisticated sound booth. I was told that my hearing capability went down to incredibly low frequencies and to very high frequencies. I was told that less than 5% of the British population have hearing this good. I can tell you that it has both advantages and disavantages, but as a result, I can easily tell the difference between a DCC sound loco with a single or identical speakers and one which has multiple different speakers. I'm sorry, but I cannot accept that two identical speakers gives as good as or better sound quality than a setup with multiple different speaker types - my hearing simply tells me that the different speakers always give better results, just as they do in stereo/hifi systems.

I can't really say any more than that. If you want to continue to believe that the addition of identical speakers improves frequency range and that your school physics lessons were wrong, that's up to you.

Graham Plowman

Martin71
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Re: retro fit digital sound.

Postby Martin71 » Wed Oct 13, 2010 3:18 am

Hi

In principal I agree with what you have said Graham and 99% of the time I will use 2 different speakers to work over a broader frequency range.

You will get no argument from me on speaker theory but sometimes when we apply this to a practical application you can end up with different results. Take your 2 x 23mm speakers both have 100 ohms impedance......not necessarily so. They are manufactured to a tolerance and I believe it is + 5%. On top of that cone membranes also can change eg some are clear and some are black with the clear membranes having a slightly broader frequency range.

I have plenty to choose from so I find the maximum difference in impedance in my 2 "identical" 23mm speakers, mount them in the same housing no more than 1mm apart and seal it fully. In this combo the efficiency has being increased. How do you think I got such good sound (well I think so) out of my n gauge locos I have done? Thats my special technique..... when I use 2 of the same speakers.

From his comments, it appears that martin, like most people, considers 'better sound quality' to be 'increased volume' but this is incorrect.

Please dont assume this Graham you are wrong. I actually go a little further than your average person. I have tested my speaker combos on a oscilloscope looking for the best range to suit Diesel or Steam.

Thats why you will never see a "20x40 bass reflex" in one of my loco's. A well sealed 20x40 ESU speaker will do a far better job, but this is just my opinion, mind you my tests back this up. I'm certainty no expert like you Graham but I know what works and plenty of people I have built locos for keep coming back for more.

Martin

gppsoftware
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Re: retro fit digital sound.

Postby gppsoftware » Wed Oct 13, 2010 5:32 am

Martin,

I really cannot say any more. I too have done lots of sound installations for people (and a couple of dozen of my own) and my own hearing confirms better results (especialy when compared to prototype) with a combination of a bass reflex and a 23mm or 40x20mm. I tend to use the 40x20 as a replacement for the 23mm wherever possible, but they are not designed to produce the low bass sounds that the bass reflex does, so I would suggest that while the 40x20 does give better sound than a 23mm, it is not handling the low end bass that the bass-reflex does so it is still chopping off part of the audible frequency range and therefore, loosing quality. Having said that, optimal speaker choice needs to be made on the basis of the recording on a loco by loco basis: some recordings consist mostly of high frequencies while other have bass-end as well.

If you were using an oscilloscpe to measure db, then you would be measuring amplitude (volume). If you were using it to measure frequency, then you would be getting a measurement of 'quality', assuming speakers designed for those frequencies were used.

Note: It was pieman who suggested that 2 identical speakers gave better sound quality, not me.

Once we get into 'subjective' opinions on what 'better quality sound' is, we really have no unit of measure on which to compare or discuss!

Graham Plowman

cassey jones
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Re: retro fit digital sound.

Postby cassey jones » Wed Oct 13, 2010 8:58 am

Hi,
Just to add my bit, I have all my 37's fitted with a bass refex in the tanks and a 40x20 on the chassis - I have tried all other permitations with speakers and this one is spot on -with 37 sounds.
SWD 50 sounds work best with a bass reflex plus 23mm, why I do not know?
SWD Class 40 sounds very good with a bass enhanced plus 23mm.
Class 31 [both SWD and Howes] sound best with bass reflex and 40x20.
At the end of the day your ears have the final say - on what sounds good to you.

C.J

Martin71
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Re: retro fit digital sound.

Postby Martin71 » Wed Oct 13, 2010 9:23 am

Hi Graham

Note: It was pieman who suggested that 2 identical speakers gave better sound quality, not me.


He also suggested a bass reflex and more importantly sealing the speaker.

With all due respect graham, fitting a speaker without the sound chamber / baffle box will produce far poorer sounds.

I think the best option with the backmann 37 iseither 2 x 23 ml speakers plus the sound boxes locted int he Fuel tanks, or a single Base reflex plus a 20 x 40 under the fan.

I have posts somewhere on how its done, but I think they are on RMWEB?



Anyway as you said sound it is subjective I have my methods Pieman has his and you have yours. I try to stay out of sound discussions and only added my part after following the link you posted which I consider an unacceptable method for speaker installation.

Cheers

Martin


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