Hiss not Hum help
I have two different outlets that are not connected, one has a Furman ac filter, the other has an APC H15. From the Focal towers, it has KK PR8 cables, to Emotiva or Parasound Amplifiers, that are fed by the Furman, then Mogamy XLR to the Anthem AVM60 fed by the APC H15, on the Anthem I have CD player, Bluray player, Chromecast, and all that. Changing the Amps, or the outlets does not help but I currently don't have multiple preamp and receivers available to test, but the hiss is noticeable only after a signal from the preamp is plugged into the amplifiers so either it comes from the wall or the preamplifier itself, but either I am super unlucky to get 3 or 4 different ones with some defect of something disturbs all the preamplifiers I had. |
I once had a hum in my tweeters. I placed a ISO-MAX ´´ 2 channels line input isolator ´´ between the HT processor and the power amplifier and the issue was solved. https://www.jensen-transformers.com/product/pi-2xx/ |
The "hiss" problem is usually because of a preamp that has an extremely "high gain" stage combined with ultra-efficient speakers. I'm not sure that your Focal would be considered ultra-efficient. These are typically the really high 98-99db speakers such as Tekton or Klipsch. I'm also wondering why you would get this hiss problem from the Anthem AVM60. Typically these HT processors have a resistor ladder volume adjuster on the output which would reduce any hiss as you turn down the volume. I would almost think something is wrong with the AVM60. It's too bad you don't have the ability to try a different preamp. You could try getting some RCA or XLR attenuator adpaters to put between your AVM60 and the amplifiers if you wanted. These will drop the signal level going into the amplifiers by something like 6db or 9db. I cannot guarantee that this would solve the problem, but it is something that people do when they have an ultra-efficient speaker. |
Doesn't the Parasound have a gain option. Turn it down. Disconnect EVERYTHING except the preamp, amp and one source. If you have tone control put them all in the flat position. A loudness option turn it off. When I say unplug, I mean from the Power supply and the RCA/XLR/EVERYTHING.. Cable boxes/routers and Laptops PS are the worst.. Go to a single outlet. If your speakers have LPads make sure they are in the 12 oclock or less position.. Turn the LPads CCW to decrease... Cable Art is something EVERY audiophiler need to learn. You CANNOT plug and drop cable runs... They have to be separated and cross at 90 degree (close) NO TOUCHING... Cables are everywhere in my house, 3 or 4 systems.. NO NOISE....BLACK as pitch background.. All behind routing cables correctly.. Cable Art... Regards |
I briefly tested today with a noise isolator and a 10db attenuator, and the 10db attenuator worked great, hiss is only audible a few inches from the tweeter, I am going to do additional testing to ensure sound quality was not degraded but I purchased a professional-grade microphone attenuator, it should be at least decent... will update further. |
The attenuator will basically reduce the entire signal level (which does include the hiss). The result is that you will have to turn up the volume control higher than normal on your preamp equipment to get the same amount of sound out. As long as you are able to get enough loudness out of your speakers to make you happy, this is a great solution. |
@auxinput, yes I understand the point of attenuators, they attenuate the voltage/amplitude of the entire signal, but I tested this at 0DB and compensated on the preamp by setting the sound to be +10DB, yet it improved and that is why I will do additional testing tonight. even if it lowers the overall top loudness I never went about -20DB if the sound is decent and hiss is inaudible at 1 foot away at 0DB, I will be happy at most levels. |
Hi all, just a quick update, I set my front speakers at +10DB on the preamp, and up to -10 DB on volume, the hiss is barely audible, for whatever reason, the preamp seems to be overdriving the amps, and the attenuator helped easy this connection. After listening to music the whole afternoon I can say the problem got solved for now. However, I will try to get "cable art" and an Anthem service to confirm no other noise source can be removed. |
In a lot of preamps, the "amount of gain" is fixed and is not really affected by the volume control. The volume control is a potentiometer or a resistor ladder circuit that lowers the signal level. The the signal is sent through a resistor circuit which drops the signal level again (this could be a large amount like 100 db). The it gets sent through the "gain circuit" which re-amplifies the signal and provides current to drive the output to the amplifier. On some preamps, there is a very large amount of gain in this analog circuit. When you combine it with a very effecient speaker, you will get a lot of hiss. It's weird that it would occur on your Focal speakers since they are a more conventional speaker, but maybe something is happening. In any event, it looks like you have resolved the problem. |
