Every time my furnace or water heater (gas, power vented) kicks on or off my DAC drops out momentarily. My audio system, furnace and water heater are all on separate dedicated ac lines. My AC panel was updated to a 200 amp service some years back. I checked all connections from the panel to each device and internally checked all electrical connections in the furnace and water heater, verifying proper hot, neutral and ground. I checked and tightened all wires in the service entrance panel. Has this happened to anyone else? If so what did you do to correct it? Any help will be appreciated.
If the audio system, the furnace, and the water heater are all on the same AC phase, I believe there is a good chance the problem would be resolved if you were to have an electrician move the system's dedicated line(s) to the other phase (i.e., to a breaker on the other side of the panel).
OK, so I started by changing the digital cable (it was the easiest). I had been using an Audio Envy cable that I really like. Had it about one month. After inserting it into the system I had an occasional drop out but didn't think a lot about it. However as the cold nights came I started having more and more drop outs. Which lead me to tracking down the cause. Thus I discovered that it was the furnace and water heater making the disruption. Prior to the cold snap, it was only the turning on and off of the water heater that caused the drop out. But now with the furnace in the mix the drop out rate was increased signifigantally. I replaced the AE cable with a Grover Huffman digital cable and last night experienced no drop outs. The AE cable is only one meter while the GH cable is 1 1/2M. Is it the length of the cable that could be the culprit or is it the design/construction differences? Either way, thanks for the suggestions to get the gremlins out. I will also look into the service panel today to check the wiring as to which leg of the mains might be in common.
The AE cable is only one meter while the GH cable is 1 1/2M. Is it the length of the cable that could be the culprit or is it the design/construction differences? 10-09-15: Jadedavid
Hopefully someone like Al, (Almarg), will chime in.
As for the AC power side of the equation when the furnace or hot water is turning on or off a transient spike is being sent out on the AC mains. Just guessing the transient causes a quick brief problem with the DAC or maybe even the transport. For some reason the AE digital cable is not capable of maintaining a good digital lock between the transport and the DAC. It's like the AE digital cable was just on the edge of maintaining the digital lock between the transport and the DAC before the transient spike event would happen causing the drop out.
Either way, thanks for the suggestions to get the gremlins out. I will also look into the service panel today to check the wiring as to which leg of the mains might be in common. 10-09-15: Jadedavid
You never said if the furnace or hot water heater are gas or electric. If electric my guess is they are fed by single phase 240Vac.
Length of the cable might or might not add to the problem. Longer cable allows to avoid first reflection adding/modifying shape of original transition (many factors involved). You GH cable might work better because of length or because of better characteristic impedance match. Most likely it is just a better shielding.
Good call on the cable, Jim (Jea48). I would not have guessed that. And your explanation sounds very plausible. I agree with Kijanki's comments as well.
Jadedavid, the reason that a length of 1.5 meters is often recommended for digital cables is further explained in this paper. It relates to the potential effects on jitter (short term fluctuations) in the timing of D/A conversion, that may result from the inevitably less than perfect impedance matches between the cable and the components that are being connected.
As Kijanki indicated, though, and as can be inferred from the paper, many system dependent variables factor into the likelihood of that length being optimal. A notable one being the risetimes and falltimes of the signal that is sent into the cable (i.e., the amount of time for the signal to transition between its lower and higher voltage states, and vice versa), which are generally unspecified and unknown. So while 1.5 meters may generally stand a greater chance of being optimal than 1 meter, that will not always be the case.
All of that relates to sound quality, though, and usually not to the kind of problem you have encountered. But I wouldn't be surprised if the characteristics of the shield relate to it, as Kijanki indicated. Given that two different appliances cause similar symptoms, though, my guess is that it is not differences in shielding against RFI pickup that are involved, but rather effects of the shield or other signal return conductor in the cable on a ground loop issue that may be occurring between the two components. A ground loop issue conceivably resulting in the marginal lock Jim referred to.
An interesting experiment, therefore, might be to temporarily put a cheater plug (a 3-prong to 2-prong adapter, with the safety ground connection not connected), on the power plug of either the DAC or the component that is providing the signal to it. That would break any ground loops between the two components. Then see if the problem still occurs with the shorter cable.
Thanks to all for the suggestions and info. After listening again tonight I have had no drop outs with the 2nd digital cable in place. However I think "Almarg" has hit on the root cause. I have been constantly fighting a ground loop hum that I cannot cure. I have tried cheater plugs on some/all pieces of equipment, plugging all the audio gear into one strip, isolation transformers ETC ETC. I have come to the limits of my knowledge of finding the source of the imbalance. Thanks for the ground/neutral info from "Cdrc". I think it"s time to call in an electrician. Hopefully I can find one who understands this type of problem.
I have tried cheater plugs on some/all pieces of equipment, plugging all the audio gear into one strip, isolation transformers ETC ETC.
What equipment in your system uses the AC power mains safety equipment ground? (Check all audio equipment with an IEC power connector for the safety equipment ground pin/blade. If only 2 blades the equipment ground is not used on the equipment.)
Are you sure you are hearing a hum or could it be a low level buzz?
It would help if you listed your equipment, ICs, speaker cables, and any after market power cords you are using.
By chance do you have a TV with CATV or a Dish connected to the system? .
FYI, I have found no correlation between length of USB cable (1m vs. 1.5m) and performance across brands. You are not assured superior quality/performance from a supposedly ideal 1.5m USB versus another brand 1m. It is also relatively easy to find a 2m USB which will outperform any given 1m or 1.5m alternate brand.
I have a few times found that 1m sounded better of the same brand than 1.5. So, you can say I'm not a believer in the idea that 1.5 is somehow magical for sound quality of USB.
I use a 2 meter digital coax cable myself. I don't think anyone here said a 1.5M was the magic length.
I think Al, (Almarg), and Kijanki offered a more technical reasoning why the digital cable made the difference and the fact that Jadedavid solved his dropout problem using a different digital cable tells others that are experiencing dropouts caused by the switching on or off of an AC mains load/s it might save them a lot of time to just change out the digital cable instead of spending maybe hours looking for an AC mains problem that may not be their problem at all. It might just be the digital cable. In the end that's all that matters. .
Jea48, Yes, I understand the flow of the conversation.
I was simply following up on Al's side comment about cable length. i.e. If someone has a choice between a 1.5m and 2m USB if possible one should try them, as opposed to thinking that the theorized ideal length cable would automatically be superior. I do, however, favor a shorter USB when I can obtain it.
I also have seen one or two instances in which a particular USB cable worked with some gear and not others. So, it is wise when experiencing a snafu with digital to consider that the USB cable may be incompatible with a particular component.
Doug, I should clarify my earlier comments about digital cable length by adding that they only pertain to electrical (non-optical) S/PDIF and AES/EBU cables. My comments don't apply to USB cables, in part because the risetimes and falltimes of USB signals are vastly different than those of S/PDIF and AES/EBU signals. As I had mentioned, and as further explained in the paper I linked to, signal risetimes and falltimes are key variables affecting what length will be optimal.
Also, I'll add that if a very short length is practicable, such as perhaps 8 inches or so, that can be expected to often be as good or better a choice for S/PDIF and AES/EBU than 1.5 or 2 meters. It is the intermediate lengths, such as 1 meter, which (depending on a complex and essentially unpredictable set of component-dependent variables), stand a somewhat lesser chance of being optimal than those other choices.
I later contacted the OP, through the Agon message system, with a question about the problem he had with drop outs. I asked him if he was still using the same 1.5M Grover Huffman digital cable. He responded no he had bought a new 1M Grover Huffman digital cable and was not experiencing any drop out problems with the 1M Grover Huffman cable.
Conclusion? Not all S/PDIF 75 ohm digital coaxial cables are created equal. Was it the RCA connectors used? Do the ends used by Grover Huffman have a closer better 75 ohm characteristic than the ones used by Audio Envy?
Was it how the RCA connectors were connected to the coax cable?
Is it the length of the cable that could be the culprit or is it the design/construction differences?
Or was it ???
-The characteristic impedance of the cable. That is why length is immaterial.
If the characteristic impedance of the cable is incorrect, there will be reflections that cause errors. This can lead to an inability for the DAC to lock onto the signal. The right cable is all that's needed. Not all high end cable manufacturers understand this, so you see a lot of variance. One cable manufacturer that does get this right is Purist Audio.