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#1
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KVM Worthwhile for audio switching?
I'm in need of a way to swtich audio between two different machines to
accomodate my wireless Sennheiser headphones. As of now, I use a radio shack RCA A/B switch, but this seems to degrade the signal. Also, I don't have to have RCA. In fact, 1/8" jack will do, given that I use an adapter to plug into the sound cards on the computers. My current set up is a Belkin Omni Cube 4 port to switch the keyboard and mouse between 2 different machines. I use the VGA and DVI inputs on a 2405fpw to share the monitor between the 2 machines. I've been meaning to check into new KVMs anyway. Do the new audio supporting KVMs maintain an acceptable audio swtching quality? I was thinking about the Belkin OmniView SOHO Series F1DS104T. Thanks for any info, Alex |
#2
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KVM Worthwhile for audio switching?
On Sat, 24 Jun 2006 15:43:55 -0500, "Alex Moreau"
wrote: I'm in need of a way to swtich audio between two different machines to accomodate my wireless Sennheiser headphones. As of now, I use a radio shack RCA A/B switch, but this seems to degrade the signal. I'm not sure where to draw the line here, since your wireless Sennheiser headphones also degrade the signal. Treble is just bad relative to Senns with a cord. What kind of degradation do you feel it is? If you wiggle the switch a little does that help, suggesting it's just not making good contact? Is the switch in a metal case and/or is it near a strong magnetic field such as next to a wall-wart or other psu? You could build your own A/B, as fancy as you want it... double sided copper clad, silver plated, silver/teflon wiring or all-on-pcb with gold plated jacks and blahblahblah, bling. It may not sound any different, than using more modest parts or regardless of the parts, depending on the cause of the degradation. Can you pop open the Rat Shack box and take a piece of jumper wire or similar (leaving box in the same location it's used in) and jumper between the switch input and output pins to see if that improves the signal? Also, I don't have to have RCA. In fact, 1/8" jack will do, given that I use an adapter to plug into the sound cards on the computers. Ok, and there are some that curse at RCA, but overall it's at least better than a bunch of 1/8" minijacks as minijack contacts tend to degrade over time. My current set up is a Belkin Omni Cube 4 port to switch the keyboard and mouse between 2 different machines. I use the VGA and DVI inputs on a 2405fpw to share the monitor between the 2 machines. I've been meaning to check into new KVMs anyway. Do the new audio supporting KVMs maintain an acceptable audio swtching quality? I was thinking about the Belkin OmniView SOHO Series F1DS104T. I wouldn't run an analog signal into a digital switchbox and expect it to be a "good" thing, not with the typical budget constrained designs put into PC parts. Even so, if all else fails it's worth a try to buy it from someplace with a good return policy, and just send it back if it degrades the sound too much as this is a very reasonable objection to product performance. |
#3
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KVM Worthwhile for audio switching?
"kony" wrote in message ... On Sat, 24 Jun 2006 15:43:55 -0500, "Alex Moreau" wrote: I'm in need of a way to swtich audio between two different machines to accomodate my wireless Sennheiser headphones. As of now, I use a radio shack RCA A/B switch, but this seems to degrade the signal. I'm not sure where to draw the line here, since your wireless Sennheiser headphones also degrade the signal. Treble is just bad relative to Senns with a cord. What kind of degradation do you feel it is? Volume degradation seems to be somewhat of an issue at times, but overall, I'm looking for the best way to retain the most quality. I'm not very knowledgeable regarding such devices, and perhaps the A/B switch is the best I can do. If you wiggle the switch a little does that help, suggesting it's just not making good contact? Is the switch in a metal case and/or is it near a strong magnetic field such as next to a wall-wart or other psu? You could build your own A/B, as fancy as you want it... double sided copper clad, silver plated, silver/teflon wiring or all-on-pcb with gold plated jacks and blahblahblah, bling. It may not sound any different, than using more modest parts or regardless of the parts, depending on the cause of the degradation. Yes, and I do have the ability for such endeavors, but not the time. Truth is, I'm busy most of the time, so buying a solution is better than building one at this point in time. Can you pop open the Rat Shack box and take a piece of jumper wire or similar (leaving box in the same location it's used in) and jumper between the switch input and output pins to see if that improves the signal? Also, I don't have to have RCA. In fact, 1/8" jack will do, given that I use an adapter to plug into the sound cards on the computers. Ok, and there are some that curse at RCA, but overall it's at least better than a bunch of 1/8" minijacks as minijack contacts tend to degrade over time. I don't mind using RCA. I just thought using 1/8" jacks rather than adapters or hybrid cabling might provide a lesser rate of degradation. My current set up is a Belkin Omni Cube 4 port to switch the keyboard and mouse between 2 different machines. I use the VGA and DVI inputs on a 2405fpw to share the monitor between the 2 machines. I've been meaning to check into new KVMs anyway. Do the new audio supporting KVMs maintain an acceptable audio swtching quality? I was thinking about the Belkin OmniView SOHO Series F1DS104T. I wouldn't run an analog signal into a digital switchbox and expect it to be a "good" thing, not with the typical budget constrained designs put into PC parts. Even so, if all else fails it's worth a try to buy it from someplace with a good return policy, and just send it back if it degrades the sound too much as this is a very reasonable objection to product performance. OK. So with the information I've given, what would you do, if anything, to limit signal loss? Any advice is welcome as long as it's not a solution that requires building. Thanks, Alex |
#4
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KVM Worthwhile for audio switching?
Alex Moreau wrote:
"kony" wrote in message ... On Sat, 24 Jun 2006 15:43:55 -0500, "Alex Moreau" wrote: I'm in need of a way to swtich audio between two different machines to accomodate my wireless Sennheiser headphones. As of now, I use a radio shack RCA A/B switch, but this seems to degrade the signal. I'm not sure where to draw the line here, since your wireless Sennheiser headphones also degrade the signal. Treble is just bad relative to Senns with a cord. What kind of degradation do you feel it is? Volume degradation seems to be somewhat of an issue at times, but overall, I'm looking for the best way to retain the most quality. I'm not very knowledgeable regarding such devices, and perhaps the A/B switch is the best I can do. If you wiggle the switch a little does that help, suggesting it's just not making good contact? Is the switch in a metal case and/or is it near a strong magnetic field such as next to a wall-wart or other psu? You could build your own A/B, as fancy as you want it... double sided copper clad, silver plated, silver/teflon wiring or all-on-pcb with gold plated jacks and blahblahblah, bling. It may not sound any different, than using more modest parts or regardless of the parts, depending on the cause of the degradation. Yes, and I do have the ability for such endeavors, but not the time. Truth is, I'm busy most of the time, so buying a solution is better than building one at this point in time. Can you pop open the Rat Shack box and take a piece of jumper wire or similar (leaving box in the same location it's used in) and jumper between the switch input and output pins to see if that improves the signal? Also, I don't have to have RCA. In fact, 1/8" jack will do, given that I use an adapter to plug into the sound cards on the computers. Ok, and there are some that curse at RCA, but overall it's at least better than a bunch of 1/8" minijacks as minijack contacts tend to degrade over time. I don't mind using RCA. I just thought using 1/8" jacks rather than adapters or hybrid cabling might provide a lesser rate of degradation. My current set up is a Belkin Omni Cube 4 port to switch the keyboard and mouse between 2 different machines. I use the VGA and DVI inputs on a 2405fpw to share the monitor between the 2 machines. I've been meaning to check into new KVMs anyway. Do the new audio supporting KVMs maintain an acceptable audio swtching quality? I was thinking about the Belkin OmniView SOHO Series F1DS104T. I wouldn't run an analog signal into a digital switchbox and expect it to be a "good" thing, not with the typical budget constrained designs put into PC parts. Even so, if all else fails it's worth a try to buy it from someplace with a good return policy, and just send it back if it degrades the sound too much as this is a very reasonable objection to product performance. OK. So with the information I've given, what would you do, if anything, to limit signal loss? Any advice is welcome as long as it's not a solution that requires building. Thanks, Alex if your switchbox is degrading quality or volume, its because its faulty. Its quite a challenge to build a device like this that will degrade headphone signals. Replace the switch or leads if necessary. NT |
#5
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KVM Worthwhile for audio switching?
wrote in message oups.com... Alex Moreau wrote: "kony" wrote in message ... On Sat, 24 Jun 2006 15:43:55 -0500, "Alex Moreau" wrote: I'm in need of a way to swtich audio between two different machines to accomodate my wireless Sennheiser headphones. As of now, I use a radio shack RCA A/B switch, but this seems to degrade the signal. I'm not sure where to draw the line here, since your wireless Sennheiser headphones also degrade the signal. Treble is just bad relative to Senns with a cord. What kind of degradation do you feel it is? Volume degradation seems to be somewhat of an issue at times, but overall, I'm looking for the best way to retain the most quality. I'm not very knowledgeable regarding such devices, and perhaps the A/B switch is the best I can do. If you wiggle the switch a little does that help, suggesting it's just not making good contact? Is the switch in a metal case and/or is it near a strong magnetic field such as next to a wall-wart or other psu? You could build your own A/B, as fancy as you want it... double sided copper clad, silver plated, silver/teflon wiring or all-on-pcb with gold plated jacks and blahblahblah, bling. It may not sound any different, than using more modest parts or regardless of the parts, depending on the cause of the degradation. Yes, and I do have the ability for such endeavors, but not the time. Truth is, I'm busy most of the time, so buying a solution is better than building one at this point in time. Can you pop open the Rat Shack box and take a piece of jumper wire or similar (leaving box in the same location it's used in) and jumper between the switch input and output pins to see if that improves the signal? Also, I don't have to have RCA. In fact, 1/8" jack will do, given that I use an adapter to plug into the sound cards on the computers. Ok, and there are some that curse at RCA, but overall it's at least better than a bunch of 1/8" minijacks as minijack contacts tend to degrade over time. I don't mind using RCA. I just thought using 1/8" jacks rather than adapters or hybrid cabling might provide a lesser rate of degradation. My current set up is a Belkin Omni Cube 4 port to switch the keyboard and mouse between 2 different machines. I use the VGA and DVI inputs on a 2405fpw to share the monitor between the 2 machines. I've been meaning to check into new KVMs anyway. Do the new audio supporting KVMs maintain an acceptable audio swtching quality? I was thinking about the Belkin OmniView SOHO Series F1DS104T. I wouldn't run an analog signal into a digital switchbox and expect it to be a "good" thing, not with the typical budget constrained designs put into PC parts. Even so, if all else fails it's worth a try to buy it from someplace with a good return policy, and just send it back if it degrades the sound too much as this is a very reasonable objection to product performance. OK. So with the information I've given, what would you do, if anything, to limit signal loss? Any advice is welcome as long as it's not a solution that requires building. Thanks, Alex if your switchbox is degrading quality or volume, its because its faulty. Its quite a challenge to build a device like this that will degrade headphone signals. Replace the switch or leads if necessary. That's all I need to know...thanks! Alex |
#6
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KVM Worthwhile for audio switching?
On Sat, 24 Jun 2006 16:30:44 -0500, "Alex Moreau"
wrote: OK. So with the information I've given, what would you do, if anything, to limit signal loss? Any advice is welcome as long as it's not a solution that requires building. Let me put my answer in context... I regularly participate in 3 different headphone oriented forums. I build my own headamps and happen to have transisters scattered all over the floor at the moment so I can match gain on them. The sound card I use for headphone listening has RCAs added to the card mounting bracket (tight fit, but on some cards it is possible to add them) and a few topology and parts alterations. The output goes directly to a headamp, I would not switch it between systems at all unless I had hand-built a switch. That's just "what I would do". I opened my prior post mentioning the minor degradation from the wireless(ness) of the headphones because I can't decide for you what degree of degradation is acceptible to _your_ ears... it is a subjective thing and I can't hear your resultant sound either way, though I have A/B compared wireless Senns. There are studio quality headphone distribution and/or amp boxes but they're not cheap. What would you budget and how often do you find you're needing to switch? Is it a problem that with a KVM, you will necessarily be switching the audio when you switch the rest... can't be using one system and listening to the other unless you did it manually which somewhat defeats the whole purpose. I would first determine what is causing the signal loss to more directly combat it. As I'd mentioned previously, opening up the switch and shorting it out of the circuit as well as considering it's location are a couple of thing to try. For all we know you could just buy another switch and swap it in for the (potentially) poor one currently in the Radio Shack box... or buy another box that looks pretty similar but doesn't have the problem. If on the other hand you had a very noisey environment and the extra cables were a problem (I've no idea if very long cable runs to the Senn transmitter could foul up transmissions), shorter cables, better shielded cables, or re-routing the cables might help (if not a combination of these). |
#7
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KVM Worthwhile for audio switching?
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#8
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KVM Worthwhile for audio switching?
kony wrote:
On 24 Jun 2006 14:37:11 -0700, wrote: if your switchbox is degrading quality or volume, its because its faulty. Its quite a challenge to build a device like this that will degrade headphone signals. Replace the switch or leads if necessary. It's not so hard to degrade low level analog signals. There was a time when a lot of Radio Shack gear was tailored towards simplistic kid's hobby use, the box could be operating as it was designed to, was never intended to be a "great" isolator of signal. but how would a switchbox degrade a headphone signal? Series R has no effect until it gets into fault proportions, capacitance ditto on a 8-35 ohm line, and parallel R again has no effect until it gets well and truly into fault territory. Higher impedance lines sure, but not headphones. NT |
#10
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KVM Worthwhile for audio switching?
kony wrote:
On 25 Jun 2006 07:06:05 -0700, wrote: kony wrote: On 24 Jun 2006 14:37:11 -0700, wrote: if your switchbox is degrading quality or volume, its because its faulty. Its quite a challenge to build a device like this that will degrade headphone signals. Replace the switch or leads if necessary. It's not so hard to degrade low level analog signals. There was a time when a lot of Radio Shack gear was tailored towards simplistic kid's hobby use, the box could be operating as it was designed to, was never intended to be a "great" isolator of signal. but how would a switchbox degrade a headphone signal? Series R has no effect until it gets into fault proportions, Define "fault proportions". theres really no need. headhones are routinely driven via many ohms series R, a functional switch will not get that into that order of magnitude of contact resistance. If it does its thoroughly stuffed. The statement is generally untrue. Series resistance causes a very easily detectable change in analog audio on any reasonably good (including consumer grade) equipment. In fact it is one of the reasons many people will use a separate amplification stage instead of using the headphone-out on a power amp (with the series resistance to the HP jack). 2 different things there. Series resistance of many ohms magnitude will change the frequency response since the phones dont have constant impedance at all freqs. But a switch of milliohms resistance is not going to make a detectable difference. capacitance ditto on a 8-35 ohm line, Where are you getting this *information*? Its what I'm qualified in. Capacitance isnt a problem because the impedance is so low. Different matter on high impedance lines, or at frequencies way above audio, or on very long lines. But a headphone lead is none of these. Cable capacitance is not only an issue but will make some outputs instable altogether. A series resistance here can help (not sound, but stability) or a ferrite bead, or other resolutions chosen in the design stage (given the target use) but capacitance is a significant issue. but this has nothing to do with degrading audio quality, so long as the amp is capable of driving the load sensibly. I've not come across any good quality kit that goes unstable when loaded with a headphone lead - if it did it would be junk grade. Novelty goods etc. Typical audio cabling is a trade-off of low cost and size, flexibility. plus durability/reliability and marketing considerations. and parallel R again has no effect until it gets well and truly into fault territory. Higher impedance lines sure, but not headphones. Define "fault territory". Will "some" audio signal get through? Yes, and you are observing that some does right now. Will the signal be preserved as much as possible (reasonably so)? No. Lets put numbers to it. A leaky switch might have 500k resistance, and this is across a line with load of 35 ohms and line impedance of anything from 35 ohms downwards. And this R consists of carbon, which is ohmic. The ratio of leakage R to line R is 14300:1, so the line level will be thus reduced to 0.99993 times its original voltage level. Since carbon is ohmic there is no distortion thus introduced. Now lets say the C is heavily contaminated with copper dust that has oxidised, forming a network of rectifying distorting resistance elements. In practice there will be more C than Cu, and the R of the C is much lower than that of Cu oxide. Lets be generaous and say there is 10% distortion of the current flowing across this leaky switch. This will give us a distortion of 0.0007%. No human being can hear that, and other system disortions will swamp this one. BTW I'm looking at the switch section of a catalogue, which for an ultraminiature switch, ie a cheap type, gives a min insulation of 1000 Mohms. Now lets spin numbers for series R. Again using low quality switches not intended for analogue use at all, contact R spec is 200mohms. With 32 ohm headphones fed via a 100 ohm R, typical of consumer audio amps, and amp output impedance of say 0.2 ohms, we get a line impedance of 100.2 in parallel with 32 = 24.254 ohms. Now when we add the flimsy switch of at worst 0.2 ohms, we get 100.4 ohms driving 32 ohms instead of 100.2 ohms. You only need look at the resistance vs frequency plot of any moving coil driver to see there wont be any detectable difference. A typical 8" 8 ohm LS has impedance that varies from 1.5-2 ohms upto 20 - 30 ohms, in series with voice coil R of typ 5 - 6 ohms. This can only be approx since they vary somewhat, but this is fairly typical. The effect of any switch resistance is lost orders of magnitude below the various types of distortion inherent in moving coil loudspeakers. If analog signal was so easily preserved there would be little point to digital transmissions. This doesnt back up what youre claiming above, as its not significantly related to it. Preseving analogue quality at af over a 2m 25 ohm line is elementary, preserving it over transmission paths is a very different matter with entirely different problems and solutions. NT |
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