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Gold Member Username: DmitchellOttawa, Ontario Canada Post Number: 4863 Registered: Feb-07 | Hey guys, Just noticed something interesting tonight while down in my music room. When I put ear up to the tweeter on each speaker, like really close, I hear a hissing sound coming from them. 1) It only comes from the tweeters 2) It only happens when the amp is on (obviously) 3) It still happens with the DAC and CDP are unplugged 4) It still happens with the lights turned off 5) It is equal volume in either speaker I've never noticed this before, but then again I've never put my ear a 1/4" from the tweeters in this room. Is it the amp maybe? Or bad power? The outlet is running straight into the panel 3 feet away with very little else wired into that circuit |
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Platinum Member Username: NuckPost Number: 15699 Registered: Dec-04 | This is called "floor noise". |
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Gold Member Username: DmitchellOttawa, Ontario Canada Post Number: 4864 Registered: Feb-07 | I'd rather not have it... |
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Gold Member Username: Stu_pittStamford, Connecticut USA Post Number: 4496 Registered: May-05 | Is this with the volume knob at your normal listening level? Lower? Higher? I'm pretty sure there isn't an amp out there with zero noise floor. The higher the sensitivity of the speakers, the more apparent the noise floor. Not sure what you're running nowadays, amp and speaker wise. Unless you hear it during quiet passages of music, you're going to get this with any amp you use. |
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Gold Member Username: DmitchellOttawa, Ontario Canada Post Number: 4865 Registered: Feb-07 | Hey Stu. Yeah, that was supposed to be point #6 - the hiss stays constant weather the volume is at zero, or at 100%. I honestly never checked for this from the tweeters in my new room, but I did in fact check for it in my old rec-room (with a different amp, mind you), and had zero hiss. Totally silent. |
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Gold Member Username: HawkbillyNova Scotia Canada Post Number: 1427 Registered: Jul-07 | Nuck, is that you ? |
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Platinum Member Username: Jan_b_vigneDallas, TX Post Number: 16907 Registered: May-04 | . Esentially Nuck is right. The noise floor of the amplifier determines the amount of "hiss", or quiescent circuit noise, you will hear through the speakers. And Stu is also right, the higher the electrical sensitivity of the speakers - the more acoustic energy the speaker makes (transduces) of any electrical energy input, the higher the noise floor level will appear against the music signal as this noise signal is a constant and only another signal played higher in level will cover it up. The speakers themself have virtually no way to produce a signal on their own. The speakers in this case are simply doing what they are expected to do. About the only way to dispense with this noise today would be a chip amp run off a battery and through single driver speakers with a roll off of the very top end. Even there, should the speakers be very high in their sensitivity spec, there will be some level of quiescent noise as this signal is called "pink noise" in that it contains all frequencies but in varying degrees which step up or down in level per octave division. Usually It is a function of each component part of the gain stages in the amplifier - including even the solder points and temporary connection points - making their contributions - and deletions - from the signal. Excellent parts selection and top notch circuit layout - typically heading towards an absolute minimum of parts and solder junctions or doing away with circuit borads and using instead point to point wiring - will minimize but never truly do away with this noise. If you haven't done your regularly scheduled house cleaning duties on your system in a while, a good cleaning and de-oxidizing of all connectors and plug in devices in your system along with a re-routing of cables with proper cable dressing techniques as an end result might diminish the noise but it will never completely disappear. In most home systems the amount of cables and their winding together as a clump has increased expotentially with the complexity and number of components. This makes it even more important to do proper cable dressing. A regular go through of your system to clean connectors should be a mandatory function on any high quality system. I would recommend at least a once yearly regime for any high quality system As push on or non-gas tight (most bananas and RCA type) connectors age and oxidize, they form small micro-rectifiers. Each connection point then becomes what would be known as a crystal radio set as it terminates an electrical circuit. Each connection will slowly tune itself to a radio frequency and eventually, if nothing is done to stop the oxidation process, you will hear faint levels of a radio signal riding on your music. Gold plated connectors have been used in audio not for their ultimate sound quality - gold is somewhat down on the list as far as conductivity is concerned - but for the material's resistance to aging. This does not excuse you from doing maintenance on your system however. As my knee is proving this AM, everything ages. If you don't know how to go about system cleaning and cable dressing, ask and we'll give you the basic run down. Cable dressing can (should) mean elevating cables above paramagnetic materials. This means keeping power and signal cables several inches away from the metal legs of an equipment stand. Any cables running close to a wall can be influenced by AC lines hidden within those walls or under a floor. Cable lifters have come into vogue to raise cables above the synthetic materials found in most carpets. Remember, the pulsing signals though a cable - especially ones fitted wth a PVC dielectric - will create small electro-magnetic fields which ride along with the signal. Since the magnetic fields are mostly random in nature and multiple in frequency they have the potential to create noise which mimics the noise of the electronics though this noise is more of the "white noise" variety as you would hear from inter-station FM hiss. Before solid state came along tubes exhibited a fairly high quiescent noise flloor. Cheap tube amps were more obvious in this respect than were higher quality tube amps and the relative silence of McIntosh and Marantz components was a good selling point for their products. But even then, through a pair of 104dB @ 1 watt Klipschorns or similarly efficient speakers, the noise could often be heard from a seated listening position. For classical music lovers this could be quite annoying as the noise floor was easily heard in between movements or during quieter passsages. And, of course, once they knew the noise was there, it was all they could focus on. For many listeners this drove them to sell their tubes for first generation transistors which only proved to be a disappointment in other areas. When someone - usually a new speaker owner - complained about this noise they had detected by standing close enough to their speaker to be just 1/4" away from the tweeter, the best response was simply, "Is that where you intend to be while you listen to music?" The system is very likely to be normal, DM. But it would be a good idea to do the maintenance anyway. . |
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Gold Member Username: DmitchellOttawa, Ontario Canada Post Number: 4866 Registered: Feb-07 | Thanks Jan. I knew you would be along soon :-) Your point about cables is a good one. I am using rather short runs for my speaker cables, so they are not even touching the floor. The power cable is running parallel to one of the metal legs on my stand. I should address that. Do you think an upgraded power cable would be of any benefit? |
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Platinum Member Username: Jan_b_vigneDallas, TX Post Number: 16910 Registered: May-04 | . "Do you think an upgraded power cable would be of any benefit?" To minimize the noise? I wouldn't think so if everything else is set up properly and there are no other problems in your home's AC service. Do the house keeping and the cable dressing first. Then, if you still want to experiment with a power cable, you have a better chance of the system being transparent enough to show any improvements. People tend to get the cart before the horse with tweaks and mods. They invest in something and, if it doesn't perform as advertised, they feel the item isn't of value. That's seldom the case. First, just upgrades are generally cumulative. You might not get to the point where tweak A is really noticeable until you've also added mod 1 and tweak B and C. If each change results in a slight improvement, by the time you have all components upgraded you would more easily notice the improvement tweak A has made should you begin to remove each device. In other words, the system must attain a certain level of capacity to allow for slight improvements to become apparent. Improvements are at times most noticeable when they are removed from the system. And, finally, you must have on your priorities list those qualities which the device would affect. I would tend more towards a dedicated AC line first and then add a good power conditioner - not just a surge protector - and possibly something like the PS Audio Noise Harvesters before I added a new power cable. Power cables are all over the place as far as selling points go. There are a few shielded power cables which suggest they can lower the noise floor of a system. Ther are also cables which suggest they are constructed with superior materials and craftsmanship which would minimize noise issues. And there are cables which claim to be more immune to the effects of microphonics picked up through cables. In theory all of this is all but impossible as the AC voltage component is far too many times higher than any other signal in your system. However, theory is just theory and what you perceive is not predictable. The technically acceptable answer to your question is there shouldn't be any improvement. But, then, the purely objective and technically acceptable answer to changing power cords would be they cannot make for any improvement - period. That is, IMO, mostly hogwash taken as a hard and fast fact by those who prefer not to accept what is possible because it is too unsettling to what they have already determined to be what they are willing to think. Get the system in its best operating shape and then, if you care to, try a cable that suggests it will lower the noise floor of the component. . |
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Platinum Member Username: Jan_b_vigneDallas, TX Post Number: 16911 Registered: May-04 | . http://www.psaudio.com/ps/products/description/noise-harvester?cat=cables-access ories http://www.stereotimes.com/acc041007.shtml Recommended, but don't expect your jaw to drop. Just a nice improvement in the perceived noise floor and the ambient clues which exist when the noise floor is lowered. . . |
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Gold Member Username: HawkbillyNova Scotia Canada Post Number: 1428 Registered: Jul-07 | Another possibility..... http://ciaudio.com/products/XDC2 |
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Platinum Member Username: Jan_b_vigneDallas, TX Post Number: 16913 Registered: May-04 | . DM, have you experimented with AC line polarity? The ideal is to have each component at the same ground potential. While a variance from this will typically result in some degree of AC ground hum, one component with a reversed ground can also add some noise to the system. I have to say I'm ignorant of the Canadian wiring systems, so possibly nothing I will mention in this post can occur with Canadian outlets. However, if the information is adaptable, you might find a slight reduction in the noise floor of the amp by having each component wired to the same ground potential. The tool to use is very cheap and should be available from any home improvement/hardware store; http://www.amazon.com/Electrical-Receptacle-Outlet-Ground-Tester/dp/B0012DHVQ0 If I remember correctly, you did the wiring to your room yourself. It's still a good idea to check each outlet in the house as mistakes are too easy to occur when you get tired. Additionally, other outlets in the house which are wired incorrectly could add noise through the common ground. Buy a few ground lifts while you're at the store; http://www.filmtools.com/grliadco41.html and check a few components by reversing their polarity. Any US two pin plug/outlet will be polarized; http://www.ehow.com/facts_7701850_ac-power-plugs-polarized.html Since virtually all current building codes say all new construction/retrofit should be three pin, grounded outlets, many components still run on two pin cables. Noise can be picked up should one component be wired in reverse to another. If you have a multi-meter, you can determine correct or "preferred" polarity of the individual components by checking each pin on the plug with one probe while touching the opposite probe to any grounded screw on the component's chassis. Many components paint the screws which hold the back panel in place so try a bottom plate screw - possibly one that holds the feet on the component. Set the meter to "resistance" and the plug pin which indicates the lowest resistance should be the ground/neutral side of a two pin plug. If this is not the identical pin on all components, add a ground lift and reverse the position of the plug on the "incorrect" component. You'll have to cut the ears off the polarized pin of the lift so you can turn it around since polarizing is meant to insure the proper orientation of all devices if the outlets have been wired according to proper polarity. Any three pin plug can be checked also with a lift but you've eliminated the path for grounding surges and spikes to find a safe earth ground. Lifts are meant to be diagnostic devices and not permanent additions to the system. If you find a component that indicates lower noise when polarity is reversed, you should contact the equipment manufacturer. If you find an outlet with reversed polarity, it should be repaired. Also adding a good earth ground by way of a grounding rod is optimum for any high quality system. If you don't have a true earth ground or your AC wiring is only attached to a cold water pipe, an electrican should install a rod and make the appropriate connections. This is all part of the basic set up of a system and I seriously doubt what you're hearing is more than the noise floor of the amplifier. But getting things right in front of the amp is how you should begin. . |