PC CPU fan
I'm getting a sort of 'beat' effect from my PC. It seems to have been
triggered (or maybe just increased to a level at which I've become aware of it) by adding a new (third) HD. I'm at my desk, and the PC is on the carpet 3 feet away, at the side of the desk. I can just hear this beat from here, behind the familiar high frequency fan and HD spinning sound. Kneeling on the floor with my ear by the PC case, I can hear the beat distinctly, at about 1 cycle per second. But my real gripe is that directly below, downstairs in the lounge, it's surprisingly distinct. By no means deafening, but it is intrusive. I'm aware of it even while watching TV. This is through carpet, underlay and 2 layers of plasterboard. I did also have mechanical noise from the fan (which itself may have been due to multiple causes, such as bearings, dust and one loose screw). But I've fixed that, and am left with this pesky beat. It doesn't appear to be anything I can stop by touching any PC panels, or even holding the fan itself. So I assume it's some sort of beat in the air itself, caused by the rpm speeds of various components being very close together? Rather like 'heterodyning' in radio terms? I'm not sure what the best approach is. Presumably I can take the beat frequency out of this apparently sensitive LF region by lowering the CPU fan speed rpm a bit? I could wire a couple of series diodes in the supply. Maybe as an initial step I should buy a new 60mm CPU fan, which is surely unlikely to be similar in rpm speed to the present one. Any advice would be appreciated please. Anyone else had similar behaviour? -- Terry Pinnell Hobbyist, West Sussex, UK |
On Mon, 03 Oct 2005 08:50:32 +0100, Terry Pinnell
wrote: I'm getting a sort of 'beat' effect from my PC. It seems to have been triggered (or maybe just increased to a level at which I've become aware of it) by adding a new (third) HD. I'm at my desk, and the PC is on the carpet 3 feet away, at the side of the desk. I can just hear this beat from here, behind the familiar high frequency fan and HD spinning sound. Kneeling on the floor with my ear by the PC case, I can hear the beat distinctly, at about 1 cycle per second. But my real gripe is that directly below, downstairs in the lounge, it's surprisingly distinct. By no means deafening, but it is intrusive. I'm aware of it even while watching TV. This is through carpet, underlay and 2 layers of plasterboard. I did also have mechanical noise from the fan (which itself may have been due to multiple causes, such as bearings, dust and one loose screw). But I've fixed that, and am left with this pesky beat. It doesn't appear to be anything I can stop by touching any PC panels, or even holding the fan itself. So I assume it's some sort of beat in the air itself, caused by the rpm speeds of various components being very close together? Rather like 'heterodyning' in radio terms? I'm not sure what the best approach is. Presumably I can take the beat frequency out of this apparently sensitive LF region by lowering the CPU fan speed rpm a bit? I could wire a couple of series diodes in the supply. Maybe as an initial step I should buy a new 60mm CPU fan, which is surely unlikely to be similar in rpm speed to the present one. Any advice would be appreciated please. Anyone else had similar behaviour? It is usually the sides of the case behaving like a drum. Try damping both sides with your hands, and see what happens. |
Michael Gray wrote:
It is usually the sides of the case behaving like a drum. Try damping both sides with your hands, and see what happens. That makes sense, but holding both sides doesn't diminish the beat. I can now *feel* it as well as hear it (~ 1 Hz). Any other ideas on stopping it? How about that rpm reduction I mentioned? -- Terry Pinnell Hobbyist, West Sussex, UK |
"Terry Pinnell" wrote in message ... I'm getting a sort of 'beat' effect from my PC. It seems to have been triggered (or maybe just increased to a level at which I've become aware of it) by adding a new (third) HD. I'm at my desk, and the PC is on the carpet 3 feet away, at the side of the desk. I can just hear this beat from here, behind the familiar high frequency fan and HD spinning sound. Kneeling on the floor with my ear by the PC case, I can hear the beat distinctly, at about 1 cycle per second. But my real gripe is that directly below, downstairs in the lounge, it's surprisingly distinct. By no means deafening, but it is intrusive. I'm aware of it even while watching TV. This is through carpet, underlay and 2 layers of plasterboard. I did also have mechanical noise from the fan (which itself may have been due to multiple causes, such as bearings, dust and one loose screw). But I've fixed that, and am left with this pesky beat. It doesn't appear to be anything I can stop by touching any PC panels, or even holding the fan itself. So I assume it's some sort of beat in the air itself, caused by the rpm speeds of various components being very close together? Rather like 'heterodyning' in radio terms? I'm not sure what the best approach is. Presumably I can take the beat frequency out of this apparently sensitive LF region by lowering the CPU fan speed rpm a bit? I could wire a couple of series diodes in the supply. Maybe as an initial step I should buy a new 60mm CPU fan, which is surely unlikely to be similar in rpm speed to the present one. Any advice would be appreciated please. Anyone else had similar behaviour? You'll need to isolate the cause of the sound. Try stopping the CPU fan briefly either by putting your finger on the centre hub of the fan or unplugging it. Don't worry about overheating, an idle CPU will be OK for several minutes without a fan before it gets uncomfortably warm. If the noise is still there, go through all the other spinning devices one by one. Disconnect hard drives and case fans and see if you can isolate the offending item. Still no luck? Disconnect the cpu fan, case fans and all the hard drives and power up. The only rotating item should be the power supply fan. If the noise is still there, that's the problem. I've seen quite a few noisy PSU fans, and the way they are mounted means they can transfer a lot of noise and vibration to the case so it acts like a resonating chamber. To confirm a noisy PSU fan, you can temporarily disable it safely by powering off, inserting a plastic rod carefully into the blades and powering back on. I've even stopped moving blades with a plastic implement without any damage, but it's unnecessary for your purposes. Never insert anything metallic or conductive. Don't run the PC for longer than absolutely necessary with a disabled PSU fan, they get very hot rather quickly! Dave |
"Dave D" wrote:
You'll need to isolate the cause of the sound. Try stopping the CPU fan briefly either by putting your finger on the centre hub of the fan or unplugging it. Don't worry about overheating, an idle CPU will be OK for several minutes without a fan before it gets uncomfortably warm. If the noise is still there, go through all the other spinning devices one by one. Disconnect hard drives and case fans and see if you can isolate the offending item. Still no luck? Disconnect the cpu fan, case fans and all the hard drives and power up. The only rotating item should be the power supply fan. If the noise is still there, that's the problem. I've seen quite a few noisy PSU fans, and the way they are mounted means they can transfer a lot of noise and vibration to the case so it acts like a resonating chamber. To confirm a noisy PSU fan, you can temporarily disable it safely by powering off, inserting a plastic rod carefully into the blades and powering back on. I've even stopped moving blades with a plastic implement without any damage, but it's unnecessary for your purposes. Never insert anything metallic or conductive. Don't run the PC for longer than absolutely necessary with a disabled PSU fan, they get very hot rather quickly! Thanks, I'll schedule that for when I don't need the PC for a while! But if this is a *beat*, presumably there are two components, not one? It may be coincidence, but I've only become aware of this since installing a third HD - a 200GB Maxtor Diamond, 7200 rpm, in addition to my two 60GB Maxtors. BTW, when it comes to disconnecting a HD to test its impact on the noise, can I just close WinXP, remove the power plug from it and reboot? On later reconnecting it, will WinXP have to go through any hardware wizardry? My experience of that is mixed, so I like to avoid it whenever possible! -- Terry Pinnell Hobbyist, West Sussex, UK |
"Terry Pinnell" wrote in message ... Michael Gray wrote: It is usually the sides of the case behaving like a drum. Try damping both sides with your hands, and see what happens. That makes sense, but holding both sides doesn't diminish the beat. I can now *feel* it as well as hear it (~ 1 Hz). Any other ideas on stopping it? How about that rpm reduction I mentioned? -- Terry Pinnell Hobbyist, West Sussex, UK You are an exceptional person to be able to hear 1 Hz! John |
"Terry Pinnell" wrote in message ... snip Thanks, I'll schedule that for when I don't need the PC for a while! But if this is a *beat*, presumably there are two components, not one? Not necessarily, it could be the natural resonance of the component/PC casing. It may be coincidence, but I've only become aware of this since installing a third HD - a 200GB Maxtor Diamond, 7200 rpm, in addition to my two 60GB Maxtors. Could be the new hard drive isn't fantastically well balanced. For example, I've had UW SCSI drives create quite a racket as they can vibrate a bit more than slower devices. BTW, when it comes to disconnecting a HD to test its impact on the noise, can I just close WinXP, remove the power plug from it and reboot? Yes, but you don't have to let Windows boot to test for noise, just hit pause at the POST screen, or hit F8 to stop Windows starting. On later reconnecting it, will WinXP have to go through any hardware wizardry? No. My experience of that is mixed, so I like to avoid it whenever possible! -- Best to not let Windows boot then. I've seen windows change drive letters under these circumstances, which may or may not be a problem for you. Dave |
"Dave D" wrote:
"Terry Pinnell" wrote in message .. . snip Thanks, I'll schedule that for when I don't need the PC for a while! But if this is a *beat*, presumably there are two components, not one? Not necessarily, it could be the natural resonance of the component/PC casing. It may be coincidence, but I've only become aware of this since installing a third HD - a 200GB Maxtor Diamond, 7200 rpm, in addition to my two 60GB Maxtors. Could be the new hard drive isn't fantastically well balanced. For example, I've had UW SCSI drives create quite a racket as they can vibrate a bit more than slower devices. BTW, when it comes to disconnecting a HD to test its impact on the noise, can I just close WinXP, remove the power plug from it and reboot? Yes, but you don't have to let Windows boot to test for noise, just hit pause at the POST screen, or hit F8 to stop Windows starting. On later reconnecting it, will WinXP have to go through any hardware wizardry? No. My experience of that is mixed, so I like to avoid it whenever possible! -- Best to not let Windows boot then. I've seen windows change drive letters under these circumstances, which may or may not be a problem for you. Dave Thanks a lot for the follow-up. -- Terry, West Sussex, UK |
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"Terry Pinnell" wrote in message ... I'm getting a sort of 'beat' effect from my PC. It seems to have been triggered (or maybe just increased to a level at which I've become aware of it) by adding a new (third) HD. I'm at my desk, and the PC is on the carpet 3 feet away, at the side of the desk. I can just hear this beat from here, behind the familiar high frequency fan and HD spinning sound. Kneeling on the floor with my ear by the PC case, I can hear the beat distinctly, at about 1 cycle per second. But my real gripe is that directly below, downstairs in the lounge, it's surprisingly distinct. By no means deafening, but it is intrusive. I'm aware of it even while watching TV. This is through carpet, underlay and 2 layers of plasterboard. I did also have mechanical noise from the fan (which itself may have been due to multiple causes, such as bearings, dust and one loose screw). But I've fixed that, and am left with this pesky beat. It doesn't appear to be anything I can stop by touching any PC panels, or even holding the fan itself. So I assume it's some sort of beat in the air itself, caused by the rpm speeds of various components being very close together? Rather like 'heterodyning' in radio terms? I'm not sure what the best approach is. Presumably I can take the beat frequency out of this apparently sensitive LF region by lowering the CPU fan speed rpm a bit? I could wire a couple of series diodes in the supply. Maybe as an initial step I should buy a new 60mm CPU fan, which is surely unlikely to be similar in rpm speed to the present one. Any advice would be appreciated please. Anyone else had similar behaviour? How many HDD's have you? I had a similar problem when I added a second 7200 HDD to my system. It was a complete ba£T@rd to solve the problem, eventually cured by moving the second drive into an external USB2 enclosure. |
"Terry Pinnell" bravely wrote to "All" (03 Oct 05 08:50:32)
--- on the heady topic of "PC CPU fan" Terry, I had a similar annoying problem with a freezer fan. It would knock like your computer at about 1 beat per second. What was happening was that the fridge was slightly tilted backwards and fan rotor was travelling up the bearing and then sliding back in one shot sharply against the backstop. Who would have thought!? Your solution may be as simple as leveling your computer's case the other way. As for the freezer fan I added a small spring on the shaft. A*s*i*m*o*v TP From: Terry Pinnell TP sci.electronics.design:511555 TP I'm getting a sort of 'beat' effect from my PC. It seems to have been TP triggered (or maybe just increased to a level at which I've become TP aware of it) by adding a new (third) HD. TP I'm at my desk, and the PC is on the carpet 3 feet away, at the side TP of the desk. I can just hear this beat from here, behind the familiar TP high frequency fan and HD spinning sound. Kneeling on the floor with TP my ear by the PC case, I can hear the beat distinctly, at about 1 TP cycle per second. But my real gripe is that directly below, downstairs TP in the lounge, it's surprisingly distinct. By no means deafening, but TP it is intrusive. I'm aware of it even while watching TV. This is TP through carpet, underlay and 2 layers of plasterboard. TP I did also have mechanical noise from the fan (which itself may have TP been due to multiple causes, such as bearings, dust and one loose TP screw). But I've fixed that, and am left with this pesky beat. It TP doesn't appear to be anything I can stop by touching any PC panels, or TP even holding the fan itself. So I assume it's some sort of beat in the TP air itself, caused by the rpm speeds of various components being very TP close together? Rather like 'heterodyning' in radio terms? TP I'm not sure what the best approach is. Presumably I can take the beat TP frequency out of this apparently sensitive LF region by lowering the TP CPU fan speed rpm a bit? I could wire a couple of series diodes in the TP supply. Maybe as an initial step I should buy a new 60mm CPU fan, TP which is surely unlikely to be similar in rpm speed to the present TP one. TP Any advice would be appreciated please. Anyone else had similar TP behaviour? TP -- TP Terry Pinnell TP Hobbyist, West Sussex, UK .... Modulation in all things... |
John - kd5yi wrote: "Terry Pinnell" wrote in message ... Michael Gray wrote: It is usually the sides of the case behaving like a drum. Try damping both sides with your hands, and see what happens. That makes sense, but holding both sides doesn't diminish the beat. I can now *feel* it as well as hear it (~ 1 Hz). Any other ideas on stopping it? How about that rpm reduction I mentioned? -- Terry Pinnell Hobbyist, West Sussex, UK You are an exceptional person to be able to hear 1 Hz! John Not at all, you can do it too. The beat he's hearing is the same as tuning a musical instrument. My question is: how accurate is the '7200' RPM? Would different models be phase locked or are they just 'close'? AND, is it a balance issue with the drives (or fans)? GG |
"Anna Daptor" wrote:
How many HDD's have you? I had a similar problem when I added a second 7200 HDD to my system. It was a complete ba£T@rd to solve the problem, eventually cured by moving the second drive into an external USB2 enclosure. This new one is the third. I had to buy a 5.25" tray for it, to install it below my DVD & CD drives. All 3 are 7200 rpm. -- Terry Pinnell Hobbyist, West Sussex, UK |
"Glenn Gundlach" wrote:
John - kd5yi wrote: You are an exceptional person to be able to hear 1 Hz! John Not at all, you can do it too. The beat he's hearing is the same as tuning a musical instrument. My question is: how accurate is the '7200' RPM? Would different models be phase locked or are they just 'close'? AND, is it a balance issue with the drives (or fans)? GG Thanks Glenn. All 3 of my HDs are Maxtors (2 x 60GB, and this latest 200GB), and all are 7200 rpm. Are you speculating that one might be spinning at 432.000 kHz, and the other at 432.001 kHz?! -- Terry Pinnell Hobbyist, West Sussex, UK |
I read in sci.electronics.design that Terry Pinnell
wrote (in ) about 'PC CPU fan', on Mon, 3 Oct 2005: I'm not sure what the best approach is. Presumably I can take the beat frequency out of this apparently sensitive LF region by lowering the CPU fan speed rpm a bit? I could wire a couple of series diodes in the supply. Maybe as an initial step I should buy a new 60mm CPU fan, which is surely unlikely to be similar in rpm speed to the present one. Any advice would be appreciated please. Anyone else had similar behaviour? Yes, with my old DIY computer with two hard drives. What is your computer standing on? If it's rigidly connected to the building structure, the beating frequencies will get into the structure and appear, amplified, in all sorts of strange places, as you found. Try standing the computer on a THICK (think 75 mm) of none-too-soft PU foam, that doesn't collapse under the weight. -- Regards, John Woodgate, OOO - Own Opinions Only. If everything has been designed, a god designed evolution by natural selection. http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk |
I read in sci.electronics.design that Terry Pinnell
wrote (in ) about 'PC CPU fan', on Mon, 3 Oct 2005: Thanks Glenn. All 3 of my HDs are Maxtors (2 x 60GB, and this latest 200GB), and all are 7200 rpm. Are you speculating that one might be spinning at 432.000 kHz, and the other at 432.001 kHz?! I think you multiplied by 60. 7200 RPM is 120 Hz. -- Regards, John Woodgate, OOO - Own Opinions Only. If everything has been designed, a god designed evolution by natural selection. http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk |
I read in sci.electronics.design that Terry Pinnell
wrote (in ) about 'PC CPU fan', on Mon, 3 Oct 2005: It may be coincidence, but I've only become aware of this since installing a third HD - a 200GB Maxtor Diamond, 7200 rpm, in addition to my two 60GB Maxtors. Try loosening its fixing screws. If that stops the beat, tighten slightly at random until the beat comes back. Reverse last step. Relax. -- Regards, John Woodgate, OOO - Own Opinions Only. If everything has been designed, a god designed evolution by natural selection. http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk |
John Woodgate wrote:
I read in sci.electronics.design that Terry Pinnell wrote (in ) about 'PC CPU fan', on Mon, 3 Oct 2005: Thanks Glenn. All 3 of my HDs are Maxtors (2 x 60GB, and this latest 200GB), and all are 7200 rpm. Are you speculating that one might be spinning at 432.000 kHz, and the other at 432.001 kHz?! I think you multiplied by 60. 7200 RPM is 120 Hz. Oops! That makes a lot more sense, thanks g. So is it plausible that a HD1 could be spinning at 120 Hz and HD2 at 121 Hz (7260 rpm) to cause such a 'beat'? -- Terry Pinnell Hobbyist, West Sussex, UK |
John Woodgate wrote:
I read in sci.electronics.design that Terry Pinnell wrote (in ) about 'PC CPU fan', on Mon, 3 Oct 2005: It may be coincidence, but I've only become aware of this since installing a third HD - a 200GB Maxtor Diamond, 7200 rpm, in addition to my two 60GB Maxtors. Try loosening its fixing screws. If that stops the beat, tighten slightly at random until the beat comes back. Reverse last step. Relax. OK, will try that, thanks. As the tray has to be removed to get at the screws, that potentially implies means a lot of rebooting though. It's too soon to be sure, but I think I've made an improvement by not using the 'locking knob' after attaching the side panel of this MESH UK Athlon 1800 PC. The LF hum is still there, but it sounds almost steady now, rather than beating. I may also try some self-adhesive insulation of some sort on that side panel. -- Terry Pinnell Hobbyist, West Sussex, UK |
John Woodgate wrote:
I read in sci.electronics.design that Terry Pinnell wrote (in ) about 'PC CPU fan', on Mon, 3 Oct 2005: I'm not sure what the best approach is. Presumably I can take the beat frequency out of this apparently sensitive LF region by lowering the CPU fan speed rpm a bit? I could wire a couple of series diodes in the supply. Maybe as an initial step I should buy a new 60mm CPU fan, which is surely unlikely to be similar in rpm speed to the present one. Any advice would be appreciated please. Anyone else had similar behaviour? Yes, with my old DIY computer with two hard drives. What is your computer standing on? If it's rigidly connected to the building structure, the beating frequencies will get into the structure and appear, amplified, in all sorts of strange places, as you found. Try standing the computer on a THICK (think 75 mm) of none-too-soft PU foam, that doesn't collapse under the weight. It's just resting on the carpet and underlay at the side of my desk. Then wood flooring and plasterboard lounge ceiling below. -- Terry Pinnell Hobbyist, West Sussex, UK |
I read in sci.electronics.design that Terry Pinnell
wrote (in ) about 'PC CPU fan', on Mon, 3 Oct 2005: So is it plausible that a HD1 could be spinning at 120 Hz and HD2 at 121 Hz (7260 rpm) to cause such a 'beat'? Maybe, but you don't need to know. I've given you two ways to tackle it. Try them. -- Regards, John Woodgate, OOO - Own Opinions Only. If everything has been designed, a god designed evolution by natural selection. http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk |
I read in sci.electronics.design that Terry Pinnell
wrote (in ) about 'PC CPU fan', on Mon, 3 Oct 2005: It's just resting on the carpet and underlay at the side of my desk. Then wood flooring and plasterboard lounge ceiling below. That's not effective sound insulation. Your wood floor will love to vibrate at 1 Hz, even if it's not tuned to that frequency. You need a THICK pad -- no, thicker than that! -- Regards, John Woodgate, OOO - Own Opinions Only. If everything has been designed, a god designed evolution by natural selection. http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk |
On Mon, 03 Oct 2005 08:50:32 +0100, Terry Pinnell wrote:
I'm getting a sort of 'beat' effect from my PC. It seems to have been triggered (or maybe just increased to a level at which I've become aware of it) by adding a new (third) HD. I'm at my desk, and the PC is on the carpet 3 feet away, at the side of the desk. I can just hear this beat from here, behind the familiar high frequency fan and HD spinning sound. Kneeling on the floor with my ear by the PC case, I can hear the beat distinctly, at about 1 cycle per second. But my real gripe is that directly below, downstairs in the lounge, it's surprisingly distinct. By no means deafening, but it is intrusive. I'm aware of it even while watching TV. This is through carpet, underlay and 2 layers of plasterboard. It's the resonant frequency of the floor itself. I'm ass-u-me-ing that you're talking about the beat frequency, which sounds like, wOwwwOwwwOwww..., is that accurate? If it's just going thumpa-thumpa-thumpa, then you need to fire your yard boy. ;-P Go either to a scrap yard or a construction site, and get something very massive, like a paving tile or slab of metal, put it on the floor where the computer is now. Put some kind of acoustic insulation on top of it, like get a discarded wet suit or some old inner tubes, and put the computer on top of that pile. Don't use "acoustical tile", because you want the opposite of rigidity here. Good Luck! Rich (of course, you could overwhelm it by playing that tape of the barking dog that seems to come up here periodically. ;-) ) |
On Mon, 03 Oct 2005 20:09:28 +0100, John Woodgate wrote:
I read in sci.electronics.design that Terry Pinnell wrote (in ) about 'PC CPU fan', on Mon, 3 Oct 2005: It's just resting on the carpet and underlay at the side of my desk. Then wood flooring and plasterboard lounge ceiling below. That's not effective sound insulation. Your wood floor will love to vibrate at 1 Hz, even if it's not tuned to that frequency. You need a THICK pad -- no, thicker than that! Apropos nothing, I once was renting a guy's basement. It was always uncomfortably cold, but there was a gas space heater, but all of the warm air, of course, floated up to the ceiling (which was the underside of the floor of the upstairs), so my feet would freeze, while my head would sweat. In lieu of walking around the apartment on my hands, I took one of those little fans - you know, the shaded-pole motor, with about a 3" (8 cm?) aluminum fan blade - and hung it from a joist to blow warm air downwards toward my bed and stuff. It went "THRUMMMMM!!!!" and my roommate/landlord didn't like the noise. Well, it turns out that he also had an old turntable (remember record players?) that he was going to toss, so he let me salvage it, and I took a couple of the suspension springs from the turntable, and hung my little fan from them. The silence was golden. :-) :-) Floors make surprisingly good sounding boards. :-) Good Luck! Rich |
On Mon, 03 Oct 2005 08:50:32 +0100, Terry Pinnell wrote:
I'm getting a sort of 'beat' effect from my PC. It seems to have been triggered (or maybe just increased to a level at which I've become aware of it) by adding a new (third) HD. I'm at my desk, and the PC is on the carpet 3 feet away, at the side of the desk. I can just hear this beat from here, behind the familiar high frequency fan and HD spinning sound. Kneeling on the floor with my ear by the PC case, I can hear the beat distinctly, at about 1 cycle per second. But my real gripe is that directly below, downstairs in the lounge, it's surprisingly distinct. By no means deafening, but it is intrusive. I'm aware of it even while watching TV. This is through carpet, underlay and 2 layers of plasterboard. Get an office that adjoins a machine shop/fab shop. I guarantee, you won't notice the noise from the computer! ;-P Cheers! Rich |
On Mon, 03 Oct 2005 20:20:01 +0000, The Cheese Machine wrote:
FWIW - Maplin's sound dampening kit (A48AK) works quite well, though not exactly cheap at 18ukp, especially against HD chassis-borne noise. Yup! Can't let them sounds dry out! -- Flap! The Pig Bladder from Uranus, still waiting for that hot babe to ask what my favorite planet is. ;-j |
On Mon, 03 Oct 2005 09:20:08 -0700, Glenn Gundlach wrote:
John - kd5yi wrote: "Terry Pinnell" wrote in message ... Michael Gray wrote: It is usually the sides of the case behaving like a drum. Try damping both sides with your hands, and see what happens. That makes sense, but holding both sides doesn't diminish the beat. I can now *feel* it as well as hear it (~ 1 Hz). Any other ideas on stopping it? How about that rpm reduction I mentioned? -- Terry Pinnell Hobbyist, West Sussex, UK You are an exceptional person to be able to hear 1 Hz! John Not at all, you can do it too. The beat he's hearing is the same as tuning a musical instrument. My question is: how accurate is the '7200' RPM? Would different models be phase locked or are they just 'close'? AND, is it a balance issue with the drives (or fans)? Well, drives shouldn't whine so much that they beat against each other's whine (there's gotta be a joke in that sentence somewhere - anyone?) - take the noisy drive back to the store, and get one that isn't eating its own bearings. Good Luck! Rich |
"Terry Pinnell" wrote in message ... I'm getting a sort of 'beat' effect from my PC. It seems to have been triggered (or maybe just increased to a level at which I've become aware of it) by adding a new (third) HD. I'm at my desk, and the PC is on the carpet 3 feet away, at the side of the desk. I can just hear this beat from here, behind the familiar high frequency fan and HD spinning sound. Kneeling on the floor with my ear by the PC case, I can hear the beat distinctly, at about 1 cycle per second. But my real gripe is that directly below, downstairs in the lounge, it's surprisingly distinct. By no means deafening, but it is intrusive. I'm aware of it even while watching TV. This is through carpet, underlay and 2 layers of plasterboard. I did also have mechanical noise from the fan (which itself may have been due to multiple causes, such as bearings, dust and one loose screw). But I've fixed that, and am left with this pesky beat. It doesn't appear to be anything I can stop by touching any PC panels, or even holding the fan itself. So I assume it's some sort of beat in the air itself, caused by the rpm speeds of various components being very close together? Rather like 'heterodyning' in radio terms? I'm not sure what the best approach is. Presumably I can take the beat frequency out of this apparently sensitive LF region by lowering the CPU fan speed rpm a bit? I could wire a couple of series diodes in the supply. Maybe as an initial step I should buy a new 60mm CPU fan, which is surely unlikely to be similar in rpm speed to the present one. Any advice would be appreciated please. Anyone else had similar behaviour? -- Terry Pinnell Hobbyist, West Sussex, UK I've had things like this happen when the hard drive bracket wasn't screwed down tightly, or the case just poorly designed so it's not as rigid as it should be. Sometimes if the floor is a little uneven and you set it a certain way, some metal part of the case will resonate, sometimes moving it, tightening screws, or sticking a piece of tape between whatever's vibrating and whatever it's attached to will help. |
On Mon, 03 Oct 2005 14:05:55 +0100, Terry Pinnell
put finger to keyboard and composed: It may be coincidence, but I've only become aware of this since installing a third HD - a 200GB Maxtor Diamond, 7200 rpm, in addition to my two 60GB Maxtors. I would think it unlikely that your two identical drives would spin at a speed that is different enough to produce a 1Hz beat. That's a difference of 1:120, or 1:360 if you consider a possible harmonic effect of the motor's three windings. AFAIK, the speed is crystal locked. Your observation in respect of the 200GB drive sounds more plausible since it could involve different crystal frequencies. -- Franc Zabkar Please remove one 'i' from my address when replying by email. |
On Mon, 3 Oct 2005 08:26:38 -0500, "John - kd5yi"
put finger to keyboard and composed: "Terry Pinnell" wrote in message .. . Michael Gray wrote: It is usually the sides of the case behaving like a drum. Try damping both sides with your hands, and see what happens. That makes sense, but holding both sides doesn't diminish the beat. I can now *feel* it as well as hear it (~ 1 Hz). Any other ideas on stopping it? How about that rpm reduction I mentioned? -- Terry Pinnell Hobbyist, West Sussex, UK You are an exceptional person to be able to hear 1 Hz! John The 1Hz is the amplitude modulated envelope (cos b) of a higher audible frequency (sin a). In other words, you are hearing a higher frequency signal whose volume fluctuates at 1Hz. sin (a + b) + sin (a - b) = 2 . sin a . cos b -- Franc Zabkar Please remove one 'i' from my address when replying by email. |
On Tue, 04 Oct 2005 15:20:02 +1000, Franc Zabkar
wrote: On Mon, 03 Oct 2005 14:05:55 +0100, Terry Pinnell put finger to keyboard and composed: It may be coincidence, but I've only become aware of this since installing a third HD - a 200GB Maxtor Diamond, 7200 rpm, in addition to my two 60GB Maxtors. I would think it unlikely that your two identical drives would spin at a speed that is different enough to produce a 1Hz beat. That's a difference of 1:120, or 1:360 if you consider a possible harmonic effect of the motor's three windings. AFAIK, the speed is crystal locked. Your observation in respect of the 200GB drive sounds more plausible since it could involve different crystal frequencies. -- Franc Zabkar Please remove one 'i' from my address when replying by email. Obviously, the near empty new drive is filled with a minimal amount of data, located on one side of the platter. This causes a considerable unbalance, causing vibration. Just put more stuff on that drive. And now I will go on with my design of a battery charger that cuts off the charging process based on weight increase of a charged pack. -- - René |
René wrote:
And now I will go on with my design of a battery charger that cuts off the charging process based on weight increase of a charged pack. Take a 12V, 100AH battery. That's 12*100*3600J = 4.32MJ. e=mc^2, so the mass gain from flat to full is e/c^2 = 5e-11N, or about 5e-12Kg. Piece of ****, but works better with bigger batteries. Paul Burke |
"The Cheese Machine" wrote:
FWIW - Maplin's sound dampening kit (A48AK) works quite well, though not exactly cheap at 18ukp, especially against HD chassis-borne noise. Thanks, I'll take a look at it. But I must say that I'm now into the 2nd day of *relative quiet* ! As described earlier, this significant change has come about simply by not using the 'locking lever' on the back corner of the PC case. In fact, I have to conclude that I must have had it in that unlocked state before installing my new HD. I can still hear *some* LF noise, but only downstairs in the lounge, not sitting here at the PC! -- Terry, West Sussex, UK |
Franc Zabkar wrote:
On Mon, 03 Oct 2005 14:05:55 +0100, Terry Pinnell put finger to keyboard and composed: It may be coincidence, but I've only become aware of this since installing a third HD - a 200GB Maxtor Diamond, 7200 rpm, in addition to my two 60GB Maxtors. I would think it unlikely that your two identical drives would spin at a speed that is different enough to produce a 1Hz beat. That's a difference of 1:120, or 1:360 if you consider a possible harmonic effect of the motor's three windings. AFAIK, the speed is crystal locked. Your observation in respect of the 200GB drive sounds more plausible since it could involve different crystal frequencies. Thanks, makes sense. Just under 1% is probably acceptable tolerance for an advertised speed of '7200 rpm'. Mind you, given that this new one is Maxtor too, and broadly same 'Diamond' range, I'd have expected the same crystal to be used. -- Terry Pinnell Hobbyist, West Sussex, UK |
"James Sweet" wrote:
"Terry Pinnell" wrote in message .. . I'm getting a sort of 'beat' effect from my PC. It seems to have been triggered (or maybe just increased to a level at which I've become aware of it) by adding a new (third) HD. I'm at my desk, and the PC is on the carpet 3 feet away, at the side of the desk. I can just hear this beat from here, behind the familiar high frequency fan and HD spinning sound. Kneeling on the floor with my ear by the PC case, I can hear the beat distinctly, at about 1 cycle per second. But my real gripe is that directly below, downstairs in the lounge, it's surprisingly distinct. By no means deafening, but it is intrusive. I'm aware of it even while watching TV. This is through carpet, underlay and 2 layers of plasterboard. I did also have mechanical noise from the fan (which itself may have been due to multiple causes, such as bearings, dust and one loose screw). But I've fixed that, and am left with this pesky beat. It doesn't appear to be anything I can stop by touching any PC panels, or even holding the fan itself. So I assume it's some sort of beat in the air itself, caused by the rpm speeds of various components being very close together? Rather like 'heterodyning' in radio terms? I'm not sure what the best approach is. Presumably I can take the beat frequency out of this apparently sensitive LF region by lowering the CPU fan speed rpm a bit? I could wire a couple of series diodes in the supply. Maybe as an initial step I should buy a new 60mm CPU fan, which is surely unlikely to be similar in rpm speed to the present one. Any advice would be appreciated please. Anyone else had similar behaviour? -- Terry Pinnell Hobbyist, West Sussex, UK I've had things like this happen when the hard drive bracket wasn't screwed down tightly, or the case just poorly designed so it's not as rigid as it should be. Sometimes if the floor is a little uneven and you set it a certain way, some metal part of the case will resonate, sometimes moving it, tightening screws, or sticking a piece of tape between whatever's vibrating and whatever it's attached to will help. Thanks for all the follow-ups. As per my earlier post, situation is now much improved. -- Terry Pinnell Hobbyist, West Sussex, UK |
I read in sci.electronics.design that René wrote
(in ) about 'PC CPU fan', on Tue, 4 Oct 2005: And now I will go on with my design of a battery charger that cuts off the charging process based on weight increase of a charged pack. Don't forget to correct for the buoyancy of the evolved hydrogen. -- Regards, John Woodgate, OOO - Own Opinions Only. If everything has been designed, a god designed evolution by natural selection. http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk |
I read in sci.electronics.design that Paul Burke wrote
(in ) about 'PC CPU fan', on Tue, 4 Oct 2005: René wrote: And now I will go on with my design of a battery charger that cuts off the charging process based on weight increase of a charged pack. Take a 12V, 100AH battery. That's 12*100*3600J = 4.32MJ. e=mc^2, so the mass gain from flat to full is e/c^2 = 5e-11N, or about 5e-12Kg. Piece of ****, but works better with bigger batteries. 5 nanograms? I'm sure Win could measure that in a force 8 gale. -- Regards, John Woodgate, OOO - Own Opinions Only. If everything has been designed, a god designed evolution by natural selection. http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk |
On Tue, 04 Oct 2005 15:20:02 +1000, Franc Zabkar
wrote: On Mon, 3 Oct 2005 08:26:38 -0500, "John - kd5yi" put finger to keyboard and composed: "Terry Pinnell" wrote in message . .. Michael Gray wrote: It is usually the sides of the case behaving like a drum. Try damping both sides with your hands, and see what happens. That makes sense, but holding both sides doesn't diminish the beat. I can now *feel* it as well as hear it (~ 1 Hz). Any other ideas on stopping it? How about that rpm reduction I mentioned? -- Terry Pinnell Hobbyist, West Sussex, UK You are an exceptional person to be able to hear 1 Hz! John The 1Hz is the amplitude modulated envelope (cos b) of a higher audible frequency (sin a). In other words, you are hearing a higher frequency signal whose volume fluctuates at 1Hz. sin (a + b) + sin (a - b) = 2 . sin a . cos b -- Franc Zabkar Please remove one 'i' from my address when replying by email. In audio(+) sometimes referred to as a difference frequency, and there are also sum frequencies...heterodyning, I think? It's been awhile... Tom |
"John Woodgate" wrote in message ... I read in sci.electronics.design that René wrote (in ) about 'PC CPU fan', on Tue, 4 Oct 2005: And now I will go on with my design of a battery charger that cuts off the charging process based on weight increase of a charged pack. Don't forget to correct for the buoyancy of the evolved hydrogen. Once it has evolved, does it turn into Helium? Have to be careful about fusing. Regards Ian |
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