7mm Rob Pulham's Work Bench - Back (again) to the LNER 06 (MOK 8F)

[Rob Pulham]

Hi Rob

Are you intending to put a sound decoder in your 8F? If so, then I'll take a couple of photos of the speaker I've put in the tender of my 8F. The sound from it is quite good and well worth the effort IMHO.

Regards

Steve

That's the long term plan Steve, photos would be appreciated.

 

[Rob Pulham]

Before going any further I started to make up the bulkheads which are made up from multiple layers. Here the instructions (or my interpretation of them) let me down again and I managed to get the overlay for the top of the front bulkhead out of sequence meaning that I had to cut a section out of it to prevent having to undo a lot of work meaning that it sits around the lockers not behind them (it was quite easy to do with scissors due to it being half etched). It isn't visible in the end result but I know I had to do it.

Front Bulkhead

Fire Iron Tunnel

 

[SteveB]

Hi Rob

Please see photos below. I got the idea of using Tang Band speakers from someone on WT, but I cant remember who. Sorry. I think it may have been Steve Cook, apologies to all concerned if I'm wrong.

If you're interested, I've only been able to get them from USA. Its quite a painless and surprisingly quick process. Here's a link to where I got them from.

www.parts-express.com/tang-band-t1-1942s-speaker-module-pair-5-1-4-x-2-1-8--264-932



I did wonder about just having the sound coming from the tender, but unless you get really close to it then its not too noticeable. A good friend of mine is investigating an option of adding a tweeter for the loco. The Tang Bands are already 4 ohms which is low as my Zimos will allow.

Hope this helps.

Regards

Steve

 

[John K]

Sorry for the interrupt Rob.
These Taiwanese speakers are good but while we are still part of the EU it may be easier to buy from Loudspeaker Freaks in the Netherlands.
See bottom line of this page.
TB speaker | Loudspeaker freaks
Best,
John

 

[daifly]

I did wonder about just having the sound coming from the tender, but unless you get really close to it then its not too noticeable.

I may be in a minority of one but I always find it very noticeable, and the bigger the loco, the worse it is. Surely it’s possible to find space in an 8F boiler for a reasonable speaker?
Dave

 

[Rob Pulham]

Thanks for the input gents, that is one big speaker

 

[Rob Pulham]

This is what it looks like with the overlays on the body. You get two options included in the kit either welded or riveted. I chose riveted because it adds a little more to the character.

These latter two show the front bulkhead now it's fitted and the fire iron tunnel which fitted perfectly.

 

[Yorkshire Dave]

Surely it’s possible to find space in an 8F boiler for a reasonable speaker?

There should be plenty of room if the speaker is mounted on the boiler/firebox ring. The boiler and smokebox become the sound chamber.

Ideally the speaker requires a response range of 105Hz to 20KHz and this is where the Tang Speakers score. Most speakers available have 150Hz as the lower response level which I have personally found is not low enough to provide the deeper WOOomph, WOOomph sound of a larger steam locomotive when it starts.

As an experiment I'll be fitting a Tang Band T1-1925S speaker at some point into one of my steam locomotives to test this theory (all my previous installations of this range of speakers have been in diesels).

Apologies for the diversion Rob .

 

[Steph Dale]

Ideally the speaker requires a response range of 105Hz to 20KHz

Dave,
Sorry mate, that's erroneous - where on earth did those numbers come from?

Steph

 

[SteveB]

I may be in a minority of one but I always find it very noticeable, and the bigger the loco, the worse it is.

Sorry to intrude on your thread Rob. Firstly I think I owe Dave an apology, I now suspect I learnt about Tang Bands from his posts.

I've just done a quick experiment with my 8F, my admittedly poor hearing can't really tell that the sound is coming just from the tender unless I'm closer than 3 or 4 feet and then I have to concentrate on the sound. I suspect it's less obvious where the sound is coming from because of the difference in the amount of bass. Really, what Dave was saying. Bass doesn't seem to be as directional as mid/high frequencies. I guess that's why even good surround sound systems only have one woofer.

I'm hoping that the 8F will be running at the Albury S7 meeting on the 21st, so if you're going then you'll be able to hear it for yourself.

Regards

Steve

 

[Yorkshire Dave]

Sorry mate, that's erroneous - where on earth did those numbers come from?

They came from the their spec sheet unless I've completely misunderstood for which I apologise.

 

[Steph Dale]

They came from the their spec sheet...

Aah - that makes some sense. The problem is that you said 'Ideally the speaker requires a response range of 105Hz to 20KHz', which to me reads as a specification. Or 'what you'd want your speaker to have under ideal circumstances'. Well, the CD standard was built upon a belief that human aural comprehension is about 20Hz - 20kHz, so your 'ideal' should be at least that, I'd propose. Tricky enough with lots of watts and cubic inches; in the milliwatts and square millimetres we're dealing with here nearly impossible...

I also cheerfully acknowledge that getting any sort of output down to 105Hz out of an enclosure that size is remarkable!

Steph

 

[farnetti]

In a previous life I was a recording engineer and so:

Steve, you are correct, mid high frequencies are more directional so a speaker near the front end of a stem loco is ideal. If there is room for a larger lower frequency speaker elsewhere so much the better to add some oomph.

Steph, the 20Hz-20kHz potential hearing range is very dependent on age. At 8Khz most people lose about 30DB at age 60 compared to age 20, presumably more at higher frequencies. As it is a gradual decline we don't tend to notice it and at age 60 or older 20Khz maybe below the threshold of hearing.

Ken

 

[Rob Pulham]

I had a very satisfying session on Friday afternoon finishing of fitting the pickups and getting the J79 for a run out at SHildon on Saturday. After a couple of minor hiccups including a crank pin bush and a wheel retaining stud coming undone she ran successfully in both directions. I do need to look at my springing of the centre axle though as there didn't seem to be any movement at all.

I took along a couple of items of rolling stock for a run out too - Connoisseur Midland Milk van and a Dragon S&D Horsebox.