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Personally, i wouldn't do this. If you want to do this and keep both me and your gear happy, i would suggest using a "dummy load" or "resistive shunt" on the unused channel. If your Wadia has RCA outputs as well as XLR's, the simplest way to do this would be to place a resistor across a cheap RCA and be done with it. So long as you use something over 10,000 ohms, you should be fine. The parts will cost you less than $5 at Radio Shack.
As a side note, one can "break in" line level gear like this too. By using "dummy loads", you can put in a disc and let it play on repeat for as long as you like. No harm to the gear and no noise in the background while you enjoy your main components. Sean
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PS... DO NOT try this with power amp outputs unless you are certain that you have resistors that are MORE than capable of handling both the power and heat dissipation. |
Sean, I would like to hear your reasoning on this. What harm can possibly come from running a line level device unterminated? |
Thanks for your replies. I need to run out for the day, but will check back in later. Thanks, Jim |
Signal is still being passed and amplified without the proper load terminations. The amplitude of signals is reduced due to the lack of current flow, but that doesn't mean that the devices aren't sustaining some type of wear and or damage.
Try taking an amplifier and running it with no load with rated input. Theoretically, there is no voltage or current flow due to the infinitely high impedance it sees as a load, so there should be no problems. Wait a while and see what happens. While you might say that this is not a fair comparison, it is. It's just that the results that occur are far more visible / easier to measure with the amplifier. The same results / circuit degradation is taking place in the line level gear, it just isn't as evident or abrupt. Kind of like a slow and punishing life rather than a more timely death. Sean
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Sean, while I usually find your responses to be well reasoned, I find nothing in this one to support your position. Just what do you mean by " circuit degradation?" You state that it occurs, but offer no explanation of how it occurs or what form it takes.
What characteristic of any component will change? I can see the argument for power amps if the speaker is part of the feedback circuitry (very unusual), or in the case of inductive kickback from unloaded output transformers in tube amps, but for line level devices there is nothing I can see that is affected. Too low of an impedance can cause degredation of components due to heat, what can too high do? I say nothing.
The overwhelming majority of line level pieces use an emitter follower output stage. That puts the input impedance of the following stage in parallel with the emitter resistor. Without the load, it is driving current through a 600 ohm or so emitter resistor. With the load, add the input impedance of > 10k ohms in parallel, which is insignificant. Other circuit topologies can be analyzed in similar fashion. |
Not all components are built to the same standards of construction or use similar circuitry. As such, i was promoting a "low cost / common sense" approach that guarantees safe operating conditons for ANY type of device.
When making suggestions / comments on forums like this, we have to think about those looking for answers in the archives too. While we may know the specifics of this given situation in terms of product make / model and design integrity, someone else may be using a very different product and assume that the answers given here would apply to their situation just as well. By suggesting that someone spend $5 to protect their gear under any given circumstances, i don't think that i was out of line. I was simply thinking ahead and offering a truly "universal" answer. Sean
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Herman and Sean,
Thank you both for your input. With gear that has xlr and rca outputs, I wonder if the two unused are "active" while the other two are in use? If so, I wonder to be safe, if it would not be prudent to put a dummy load on the unused, same things with amps. I suppose it depends on the design of the make and manufacturer. I will send an email to Wadia and see what they have to say; there was nothing in their manual. Thanks again, Jim |
very unscientific answer. |
Hi All,
I spoke with John at Wadia. We are ALL CORRECT. He said there would be no issue with running one channel. And further suggested to not put a dummy load on the un-used side. However, IF dummy loaded PROPERLY, that would be no issue, but not necessary, so don't risk it. I did not ask what proper dummy loading would be. Also, all four outputs are "buffered" ??? for the same load - I probably am relaying this incorrectly, but that you can actually use all four at once.
Thanks again for everyone's thoughtful ideas and insights,
Jim |
Of course, that assumes that John is correct. I guess I need to understand a little more about my equipment and electronic principles. If I was unable to get through to Wadia (they called back), I probably would have investigated dummy loading. FWIW, for those folks reading this in this archives, who are looking for input on running a single channel from their CDP, I would get in touch the manufacturer, and if unreachable, investigate a dummy load to be safe (but make sure it's done correctly). I wasn't so confident that Wadia would get back to me as quickly as they did; This has not always been my experience.
Thanks again,
Jim
Jim |
