I'm very close to buying a DCC system; in fact, my small N scale display layout (2 back to back 2x8 modules that disassemble for transport)has it's basic double loop mainlines complete and wired for DCC and analog operation is very good. I am favouring the Digitrax Radio Super Chief II. One thing I don't have a sense of is how loud the humming or buzzing of DCC engines is, caused by the frequency of the full-voltage pulses. Only Lenz now offers a "silent" decoder for N scale and none of Digitrax' N scale decoders offers ultrasonic or "silent" operation. So, subjectively, how much of an issue is it to those of you who use it, especially in N scale? Does it bother you, put you off at all, or is it really not that much of an issue? I eventually want to use sound-equipped engines, but will the basic noise of the DCC system be too much to make use of sound decoders? Appreciate your instinctive reactions to this, I hope I won't be in for a disappointment after spending all those $$, esp. using Canadian $! Thanks.
My N gauge Atlas GP38 has a lenz decoder in it and it does run very quietly about the same level of sound as I get from analog Atlas locos. I know you are asking about other decoders but so far, I have only had the Lenz experience. Now the hobby shop I frequent has a display and runs HO and N locos and so far, they all run quietly as do the locos that I have seen at shows. I have no idea what decoders they were using. My DCC system is Didgitrax Empire Builder with a DT400 throttle. I was advised by the hobby shop that DCC uses pure DC with no pulses so I believe all locos should run quietly. The reason he told me this is because Digitrax will run analog locos using address 00. He said some analog locos will not run as well because of the lack of pulses. [ 30 March 2002, 04:22: Message edited by: Robin Matthysen ]
Thanks for your opinion, Robin; it is somewhat of a relief since I have a couple of non-DCC Atlas GP38s (and a bunch of other Atlas/Kato engines, a few with decoders); my understanding is that DCC actually puts AC at full voltage on the rails (typically 12V or less for N), this is converted to DC within the decoder by diodes/rectifiers. Command stations send DCC packets to the track at around 200 times per second, each packet containing the data needed to control the engine. Within the packet, full voltage pulses at anywhere from 30-24,000 Hz and of variable length actually cause the motor to turn. Most decoders use 30-300 Hz which is audible and can cause buzz/hum; the "silent" ones use 16-24K which is outside most adult humans' hearing range.
It is AC on the rails. That is why when you just open the throttle one click you start hearing a hum. The hum quiets down the faster you go to the point where it isn't audible. I personally don't find the hum too bad. Again, once the train is moving I don't hear anything. If you are running an analog engine on channel 00 the noise is really noticable though from speed step 1 all the way to 128.
Well, DCC isn't straight DC or straight AC. DCC is Pulse-Width Modulation on DC. It is basically a Digital carrier signal. So if you looked at a plot of DCC voltage, it would look like a square wave (AC voltage is a sin wave). Analog locomotives still work because it makes a higher constant pulse when that is activated (kind of like turning an Analog throttle up). You are correct about the frequency part, because it is still a waveform. However, in order to get an accurate voltage reading from the rails with a multimeter, you must set it on AC. All that aside, I just installed two Digitrax DN149K2s in Kato SD40-2s, and did not notice any difference in the sound output of these locos. Digitrax certainly has silent running in HO scale, and they may not "announce" the addition of silent running to their N scale line. All NCE's decoders are now silent running as well.
Noise in engines? Haven't heard a bit off it. We run 75% DCC on my club layout and 100% DCC on the home layout. No noise that I can hear. If anything is going to heard on the layouts it is the sound of a train going thru trackwork. Most of my engines are steamers, with a few of those new-fangled diesels for show. I have more problems with engines and conductors arguing over how to switch a siding than noise coming from the engines.
Agree with Mark here. I run all steamers and none of them makes any kind of motor or electrical noise that I can here. The only time you will get a noise is if you run an analog loco on a digital layout. They whine like a SOB ........Mike
I agree with Mark as well.... can't imagine the benefit of a "silent" decoder. However, it doesn't matter what system you get, if Lenz becomes your favourite decoder then go with those decoders, even though you purchased Digitrax. I too have found Lenz seems to make a bit better decoder (smoother) but I too have the Digitrax chief (but not the two).
Add me to the list of folks who have no idea why "silent" decoders are needed. I have mostly Digitrax decoders, and a couple older Lenz. I have no noise problem. When I read in some forums comments about how wonderful the silent decoders are I wonder why others have a noise problem and I don't. Even the cheap DH121 are silent. They have other problems, but not noise! Gary
A "quiet" loco?!? I've yet to hear one. I've never bothered to try and make a loco quieter, always thought it was prototypical anyhow!
I've found a low hum with my Atlas decoders in Athearn engines. However, I think it has more to do with the Athearn motor than anything else. I have plans to Sagamize these units, so time will tell. Usin' Atlas and happy, I remain: B-Dubya
Well, I can answer my own question now that I have DCC (Digitrax Super Chief II Radio). An Atlas SD35 with the factory-installed decoder (Digitrax DN146A I think) has a definite hum/buzz at extremely low speeds, but it is not offensive and disappears beyond the creeping stage. A Kato SD90MAC with the PNP Digitrax decoder (I forget the no. of it ) makes no noise to speak of at any speed. So my worries about this issue are evaporating, along with my bank balance!
As a fellow Canadian I can relate to your bank balance problem. The big negative of DCC for Canadians is the increased costs. Have you priced decoders for the N SD90"s yet..... lol.
folks 92 of my 102 N scale locos are DCC equipped (91 Digitrax, 1 Lenz). Out of my 28 SD40-2 there's one that's a bit noisy. Also some older Kato and Kato-made Atlas units are noisy. SD90's and C44's for example are silent. So what's causing this noise ? It's the motor. Let's take a closer look. Power is applied to two terminals going thru two tiny copper springs going thru small brushes onto the contacts on the turning part of the motor (guess the word is commutator). There's an electric current which depends on some kind of mechanic (spring-brush-commutator). I used to race with electric R/C cars for a decade encountering similar problems. If you're engine is humming there could be three sources : - copper springs are either to soft or to hard (short or long respectively) - the brushes are worn out or dried out - the commutator is dirty or worn out Uh, brushes dried out ?? What's that ? Well, the brushes (these small round pieces of coal) are soaked with some fluid making them smooth and providing good contact. This fluid dries if the brushes become old or are over-heated. (I used to change them on my R/C car motors every 20-30 minutes of running time) Springs to soft ? There's a relationship between the spring and the brushes. Hard springs and hard brushes gives another motor characteristics as a soft/soft combination. If the springs don't match the brushes you have poor performance or noise. Also if overheated they become softer. Dirty commutator ? Clean it with some contact cleaner or a soft rubber. This three steps should help to reduce motor noises. My experience shows that older motors are noisier than the newer ones.
I have a small fleet of diesels with many different decoders and there is defintely a need for silent decoders with some locomotives. I have an atlas GP40 from the later run and the Atlas dual-mode decoder I install hums rather loudly up to 1/2 throttle. My atals U23B with a NCE silent decoder makes zero motor noise. My kato sd40-2 hummed loudly on a DH120, but runs silently with NCE silent decoder. Maybe those of you guys who can't hear the difference are running a better DCC system I'm using the Atlas Master DCC. Could it be the booster helping raise noise levels???
What'd you say??? I couldn't hear you! Actually, what I was wondering is if you have any pictures of your modules? I'd be very interested in seeing what you've done! Thanks
There are a few different noises associated with a DCC model train engine: One is gear noise and no decoder is going to do anything about that. This noise is mechnacal - generally a grinding sound and will usually get louder as the speed increases. The second noise is an electical humming sound. This is only noticable when you are close to the engine and it is moving very slowly, as the engine picks up speed it the hum sound will go away. This sound is not coming from the decoder but is coming from the motor itself (and is caused by the decoder.) Atlas Dual Mode decoders create this low speed hum - and the GP38s that I have seen (run at the club) also have a rather loud gear noise at speed - both can be fixed. BTW - Soundtrax decoders also produce motor hum at low speed but you usually can't hear it cuz the hum is drowned out by the sound!
The second noise is an electical humming sound. This is only noticable when you are close to the engine and it is moving very slowly, as the engine picks up speed it the hum sound will go away. This sound is not coming from the decoder but is coming from the motor itself --------------------- This is the best description of the noise problem. It is definitely coming from the motor at low speeds. This is where a good quality decoder can help. The higher the frequency the motor is driven with, the closer You get to a "flat" DC voltage. I know, some folks might not like to hear this, but Zimo is still the only manufacturer to my knowledge that builds a decoder that drives the motor at 32kHz to eliminate this noise. And no, the price is not higher than a comparable decoder from it's competition running at a lower frequency. OTOH, if the buzzing doesn't bother You, You don't need high frequency. Except of course if You want to run a core less motor, such as a Faulhaber, then high frequency is a must! Art mrsonline.net
Congratulations ART, you're the smart one. As I said in an earlier post about what DCC system do you use, if I went to DCC, Zimo is the only system I would consider. All the others are playing catchup. I'd spend my money on the system that is way out front of everybody else.
