The new version V 4  (not that new now, I suppose), Loksound decoders prefer an impedance of 4 Ω, so I use two 8 Ω sugar cubes in parallel (gives 4 Ω).  It seems to give me a louder result - especially if I can mount them in phase and opposite each other.  Some people call this a hyperbaric effect.

I find that, just like my TV or stereo, the volume knob is about 1/4 to 1/2 up; and the sound is rich and plenty loud enough.

Isobaric, hyperbaric (not really a recognized term in speaker design, seems to be coined by the folks at SBS),these are all attempts to get 11 foot long wavelengths (100 hz) from 1" speakers with not enough cone movement. 300-600 Hz as the lowest output is more realistic. Probably better off using 2 amplifiers driving 2 different speakers with different frequency ranges (mega bass and regular rather than 2 identical ones), and cutting the ranges with a cross-over circuit. The only DCC controller in HO/OO I know of of with 2 amplifiers on board that are independently variable are from QSI. I'm putting one of these in my EMD E7A.

"Mega bass" speakers have a lot more cone movement, and get lower bass output. 

Anybody interested check out https://sites.google.com/site/markgurries/home/dcc-projects/two-way-speaker-system

It's a pretty simple circuit that can be tuned . There are many more.

Nigel

I knew that I'd be wrong.   :roll:

I've tried those so called bass boost speakers.  A waste of money.

My system works for me.

Hi Jeff. Thank you. I went for the easy option? And sent the Loco to Bif , as my " close up soldering/ small  job " eyesight doesn't come up to standard anymore . Which was my reason for my thread on " Magnifying Specs/Loupes"That way I will never learn, but, I thought this time it would be better to be safe than sorry. After waiting so long for the late arrival of the DJM Class 71
All the best. Kevin

I know what you mean, Kevin. I have been using an Optivisor knock-off more and more for the close up work.

Where expensive sound decoders are involved I don't blame you for being cautious. For the 8-pin versions of the LokSound decoders which have the speaker wires already soldered to the decoder (and usually come with a standard 23mm round speaker), I play safe by cutting the wires half way along, so that any soldering of wires or joints is done away from both decoder and speaker(s) - keeping the heat away from them as much as possible, and also allowing a safe margin for any cack-handedness.
 

Hi Jeff.   Thank you for your reply, how do you find the "Optivisor, knockoff" ? Is it a bit top heavy or clumsy?? That is where I find the iPad comes in handy, just open up the image with a finger and thumb. I sure that my eyesight started to fail with the purchase of a computer . But it is so convenient.   Kevin

Kevin, are you relying on a built in cam in your iPad ? I'm wondering if a web cam display on a 23" monitor would work, must try it, I'll report back later.

Hi Mike.    Yes. And I managed to get some photos on "YMRC" taken with my iPad , but  Technology is another "Country" to me, and my passport is out of date.   Kevin

Jeff, Max, Kevin,

Good point about cutting the wires. Rather than use solder to reconnect, use 2 pin connectors (Miniatronics or similar), and a metal heat sink between the join and decoder (I have some metal clothes pegs with flattened ends that clamp on the wire). One thing I've found useful when fitting multiple speakers is to lay them out, face down, and all in the same orientation. Mark one terminal with a red felt-tip. That way you ensure that they are wired in phase. Two speakers sounding louder than one? - I have a feeling that could be subjective. What you can do with 2 speakers is to up the output, given that we normally drive one speaker at 30-50% power. I know with the QSI board it is louder, but that's with 2 amplifiers.
 
"Mega bass" speakers. Max, I agree with you, WOT as most of the time they sound distinctly muddy. There is a reason for that. They need a crossover to make sure they are only receiving the lower frequencies (below 1-2 kHz). and the other speaker is only receiving above 1-2 kHz. That's why audio speakers have crossovers, bass speakers are useless when it comes to higher frequencies. Bass speakers also tend to be non-directional. I'm tempted to try a crossover design on one of the brass coffee grinders (4-6-2 Pacific) which has a really big tender with room enough for a dedicated crossover circuit and a large bass reflex speaker, and plenty of space in the boiler for a "tweeter". The brass Tenshodo SD7 (C-C) also has plenty of interior space for the circuitry and speakers. Rule 1 applies here, as audio is highly subjective.

We hear between 20 Hz and 20 kHz, which is a wavelength of 56 feet to around 0.6 inches. I'm amazed that the designers of small speakers can get them down to 300-600 Hz by messing around with the cone throw and/or air mass throw via baffles or porting. Way beyond me. One problem with cheap sound decoders is that they also come with cheap and often inappropriate speakers. Swap them for a decent one and the sound is much better. Something to watch for with the forthcoming Hornby entry-level sound decoders.

I see DCC supplies has a bass reflex speaker which is a ported design, and is supposed to achieve lower frequencies. Looks to be a Zimo product. No specs that I can find, so who knows. Zimo also do hyperbaric speakers. Watch the power requirements for these specialized speakers, they can be relatively inefficient and need 3 watt drivers. OK for the O scale folks, tenders only for us common mortals in HO/OO as the decoder boards are big. Which rules out most diesels with that big lump of metal chassis inside.

Kevin - good decision, if in doubt get somebody to do it.

Nigel

Hi Nigel, Jeff and Max.  You have hit the nail squarely on the head. After waiting so long for my class 71, the best part(Or worst) of Two Years I didn't want my first Loco sound fitting to go so badlywrong and regret my decision, maybe I should go for a cheap? preowned loco, otherwise I will never be able to do it. All this talk about Bass makes me think of Angling.
I am still looking for a "Man Cave" with a house attached, and that is really distracting me from doing much with my layout plank(proving ground work) and all the other jobs.     All the best. Kevin

The extra volume may be subjective, but also due to my sealing the speakers and their enclosures as well, so down to a combination of factors.

Anyway, in trying to get smoother and quieter (no chattering!) low speed running on E5003 (my non-sound fitted 71) I have played around with the settings on the Lenz Silver+ 21 decoder through Decoder Pro on the computer. I turned off the BEMF completely, then tweaked the start voltage to a value of 14 (after several experimental values ranging from 1 to 15). There is a bit of a delay on moving off when the throttle is opened but the slow running is absolutely dead silent now, as it should be.

After all of this, though, having temporarily tried a TCS EU621 decoder which gave beautifully smooth running through the whole speed range but messed up the lighting functions completely, I have ordered a Zimo MX634D, and when that arrives I'll pop that in to see whether I can improve things further.

Now, to the other problem with E5003's lighting; I had worked out that by remapping a function to work aux 3, the headcode lights could work even with the four function ESU decoder. It seems that Dave Jones designed the PCB so that it allows for logical outputs too (it has an amplifier circuit to allow power to be fed to anything attached to the aux 3 output). However, when I set it up, the headcode lights went out when I selected the cab lights at one end. I solved that by rereading the function mapping sheet in JMRI, and worked out that I must have gone a bit cross-eyed when I ticked the box for F20 on line 28 … what I had actually ticked was the 'off' part of F19. Having now corrected that, the headcode lights work as they should when F20 is selected for the ESU LokSound decoder. JMRI Decoder Pro makes it so easy to do these things without ever having to know which CVs you are changing or the values needed.

The lights were a bit bright so I dimmed all of them a bit while setting up the profiles in Decoder Pro, but after the photos were taken I dimmed the lights even further.





​

Hi Jeff.  Thank you for your explanation, but, that is too technical for me by half. I must take the Powercab manual to bed with me, trouble being, I although I learned to read a long time ago I don't read enough now. I did notice that one of your Loco's had a different number,are they both DJM Loco's? Do you prefer the look of the one with the valance fitted? I made an error and ordered two Thumpers with identical numbers, I was thinking about changing one of them, is it an easy job and  can I get a set with the same font? All the best. Kevin

Not necessarily in any order:

Both class 71s (or HAs, if you prefer) are DJM models. E5004 is in early green with red and white stripes, E5003 is in the later, slightly darker green with small yellow panels and no stripe. Neither has the full front valance fitted, although they are included in the bags of bits. Both have tension lock couplings, as supplied, fitted at both ends.

Bachmann and Hornby locos and units are not too difficult to renumber. I remove existing numbers with any of a number of different methods.:
1. T-cut (or many other equivalent car cutting polishes will do the job). They do remove a layer of paint so don't rub too hard but be patient and get a little off at a time.2. Wooden cocktail sticks. toothpicks or lolly sticks will abrade the numbers. Again, be patient and take your time.
3. Track rubbers or ink rubbers will remove the numbers quickly, and also a layer of paint. These can leave a rough, slightly discoloured patch, but a quick, very light polish with T-Cut fixes that.

I use waterslide transfers available as complete sets from ModelMaster, but Fox Transfers also offer similar styles.

I haven't any handy photos of renumbered units, but if you look back a few posts, you'll see Bulleid light pacific 34072 that was renumbered using these techniques and ModelMaster transfers and etched plates. I had to remove the top layer of weathering over the numbers as well on this particular model.

I have also been a bit lazy on some renumberings in the past, changing only one or two numerals, but if the colour, typeface and size don't match exactly, they do show up the differences. A touch of weathering can sometimes help, but not always. This can be seen if you look carefully at my SLW class 24, renumbered by taking off the last numeral only from D5016 and replacing it with a '7' from an HMRS sheet of BR numbers; the '7' is very slightly shorter and whiter than the other numbers. I may correct this some day.

Hi Jeff.    Thank you. Perhaps I better leave well alone? But, if I can find a suitable trailer for one of the Thumpers  from a 4 CEP or similar and have a three coach set? That "Will do nicely", and then I will not bother with numbers .All the best. Kevin 

Give it a go, Kevin. Once you have removed the original numbers (not all that difficult), the replacements are easy, particularly if you use waterslide transfers.
In the unlikely event you mess up the new ones, they'll come off again even more easily so you can have another go. It'll be good practice for your modelling skills and also give you a sense of achievement when you successfully finish the model; you will have something that is unique to you and your collection.

:cool:

Hi Jeff.   Thank you for your reply, but I will have to sort out my close up work first. If I can finish one of my many part built kits? Then that will give me something to paint and then apply transfers to, if only for practice??Top of the shopping list a secure " Man Cave", then a "Magnifier" , everything else will fall into place.All the best. Kevin
PS Jeff did you ever have or look for an 0-6-0 P Class, especially in DCC?

Mine is a fairly low speed layout, with the intention being to allow viewers to see the trains glide and snake past. When the upper level is eventually operational, the trains have a length of viaduct to wend their way along too.

Even so, with the discussions elsewhere on top speed at the back of my mind, I decided to video trains running at what I consider "reasonable" speeds for my layout. 

Using my NCE Power Pro system with a 15 V power supply, the two DJM class 71s are seen here with E5004 with Lenz Silver+ decoder on a Pullman train with lights on speed step 91 (out of 126), while E5004, with ESU LokSound v4 decoder is on a milk train at speed step 43.

While they could both go a little faster than this, it wouldn't look particularly comfortable in my layout's setting. I'll let others be the judges of what would suit their wants or needs.

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Hi Jeff as you know I didn't want to take any chances with my DJModels class 71, and I returned everything including the Loco which the postman delivered today. I did receive an email confirming everything was working and it was on its way to me. There is something that is puzzling me in the box as one would expect is the blanking plate, but with it there is a speaker( I am awaiting a reply about the why's and wherefores) but before I run the Loco , can you guess why if I have purchased a speaker? Only to have one returned, what this one is all about?   Kevin

Sorry Kevin. You'll have to ask the person who included the speaker.

Hi Jeff.  Thank you. In the meantime I received a reply to my email, the speaker was the original speaker in the Loco and was returned to me (because it was my property).   Kevin