Hi all, I've just taken delivery of a Parasound Halo P5 stereo pre-amp. I was previously running the turntable through my integrated AV receiver, and listening to vinyl via the headphone socket. I dont remember getting any hum. I was using a no brand, shielded RCA cable with ground wire. In anticipation of the P5 arriving I also thought I would invest in some better quality phono stereo leads, and after some research bought some QED Profile leads. I decided to strip the ground wire from the other phono leads I had and use that. When everything had arrived, I set it all up, but when I powered it up there was a very noticable hum, including regular 'tick-ticks' every couple of seconds, which for want of a better comparison, sounded like a record when the needle was left in the run out groove. It was dead silent on any other input, just the phono imput did this. I was trying to check connections, and noticed when my hands went near the phono connectors on the back of the P5, the hum increased. After checking the ground wire, and even disconnected it I thought I would try the old cables I was using, lo and behold the ticking was removed completely, and the hum was barely audible at normal listening levels, but audible if the volume was turned up. All of this even with the turntable powered off. So, have I received some duff QED profile interconnects? They cost £25, the existing ones were thicker but I would expect the shielding to be better, not worse to the point of unusable. Are they meant to be used for normal stereo interconnects (ie CD) and not phono? If so I will keep them for when I eventually connect up other stereo equipment. Lastly, would better (specialist) phono interconnects eliminate that hum, or is slight hum at normal listening levels normal and acceptable? If better interconnects, can someone please recommend some? Thanks! Mark
It may not be the cable. Sounds like you made a very big upgrade with your phonostage. If so, it could be revealing an electrical issue as well as improving the sound of your records. Better cables might help but it doesn't take very expensive cables to work properly. The first thing to do is check the ground (or earth in your part of the world), try it connected and not connected which you have already done. I will tell you this, I have had a refrigerator and a street light cause trouble in my phono stage in the last couple years. FLuorescent lights and dimmer switches can also be the cause of trouble. IF you are getting the noise when the turntable is off, is it still happening if the cables are removed from the turntable or the receiver? Are you getting the noise when you run a different source? Sure try new cables but very basic ones should do the trick. Try a different power outlet or try moving the equipment to another room and see if it keeps happening.
Is there anything with a wall-wart power supply or large transformer that is a bit close to your turntable? If so, rearrange your equipment so that it is farther away. I know things like the Rega TTPSU and amplifiers with large transformers can create interference that you'll hear through speakers. Re: cables, I would say the brand doesn't matter, but the fact that they are shielded does. Don't automatically assume that because a cable is thicker and/or more expensive that it has better shielding. Look at the specs of the cable. I would also check all wires and all connections that run from the phono cartridge down to the speaker wire. If anything is loose or not hooked up right, that could cause hum.
That's good, unplugged from the table or the receiver? If it is disconnected from the table and not the amp, it could be something in the table. Any two RCA cables and virtually any wire as a ground should work as a phono cable without a humm. If you can "prove" that the cables are sound then I would look at the connections to the cart and the wires in the tonearm.
These noises can be very frustrating. I won't carry on with a long story but I was literally using an AVR as a preamp and every so often with some critical listening I could hear a faint buzz in the background. I would ask people, "Can you hear that?" and it would be "I think so" I upgraded to a nice line stage preamp and that faint buzz became a show stopping trainwreck.
As soon as I took out the first cable from the back of the pre-amp the hum reduced, and when the second one was out it disappeared. When my fingers went near the QED cables when they were plugged in, the humming got noticeably worse, hence the question about those cables. Am I correct in thinking that some background hum is normal as you crank the volume? As I said, right now with the old, thicker, cables the ticking has gone and the hum only noticeable at all when the volume is increased to above normal listening volume. I don't want to be chasing the impossible, but if background hum is not normal or acceptable I will look some more. Re: cartridge connections, I get the same level of hum when the turntable is off, so I'm not sure it would still cause hum in that instance?
No, a hum isn't normal. IF we are talking about having the volume completely turned up and no signal coming from the source then yes, you are not going to get a completely black background and could hear a hum. I'm sure that Parasound has loads of power and that will push some of that forward. You have a nice amp, get some nice cables. You will at least eliminate that thought and there will be a benefit to the sound quality. If there is a distracting humm at every volume, the advice to move equipment for experimentation is pretty solid.
It sounds like you have some bad connections and shielding from the turntable. Check to make sure that the cartridge connectors are tight and on the right pins as they should be. Sometimes a cheap cable has better shielding. So just use what works. I'd also look at how close the phono stage is to other equipment. -Bill
Sounds like the cheap cable is better shielded than the QED, also sounds like you're routing the phono cable near some kind of digital gear or switching gear or cell phone or wifi router or something which would explain the occasional tick. The hum, I dunno, the trick is to diagnose where the hum is coming from -- some environmental source most likely: is the turntable near any power supplies or other audio electronics, esp. anywhere near the transformers, or near computers, are there fluorescent lights nearby?
I'm a bit confused about the reference to "I was using a no brand, shielded RCA cable with ground wire." So the ground wire is built into the ICs? Have you tried just taking a single conductor ground cable and running it from your TT ground to the grounding screw on the wall outlet? I've fixed more than one hum problem doing this. Working in general remodeling, I always had a coil of 12 gauge, green jacket solid strand cable around (you can buy it by the foot at the home centers and it is used for all general grounding purposes by electricians, TV cable contractors, etc). 12 gauge is certainly overkill but it's what I had for general wiring purposes and it's done the trick. It's worth a try if you can't get rid of the hum by other methods and it is certainly cheap enough to try.
No, when I bought the turntable I bought one of these, I just searched my mailbox to find the actual order and it was a lot cheaper than I thought. It has a separate 3rd wire for ground Twin RCA Shielded Phono Audio Cable Oxygen Free Copper & Tag Wire 2m - PSG00279 - kenable for HDMI Optical TOS Network Ethernet RJ45 Scart Audio Phono Jack USB Firewire 800 ADSL Cable Leads I pulled that off the cheap leads and used it with the QEDs. I could try 'better' ground wire, but I understood anything should be good enough, plus when I was trying to isolate the initial, very bad, problem I had those old cables connected before reconnecting the ground wire, and the current (better) level of hum did not change at all that I could here when the ground was reconnected.
The turntable is in the same position it was before adding the pre-amp, on a table about 3' from my AV amp, virgin media box, TV etc. It is also a few feet from same the power outlet, but I did also swap in a bigger, 8-way, extension lead. That lead is plugged directly into a wall socket, and the only equipment on it now is the pre amp and turntable. The pre-amp at the moment is sitting on a table in-between the TT and AV equipment. I could try moving the TT further away in case the proximity to the pre-amp is causing the hum, but I assumed a quality pre-amp shouldn't do that? I also assumed that if the TT was switched off, it would rule out any interference it was getting? As a reminder, if just the pre-amp is on and I have my headphones plugged in, on any other input apart from phono it is dead silent (I have nothing else connected). With just the phono leads connected, including ground wire to the TT, but the TT powered off, I hear the hum. As I've been woken up by the baby and probably wont get back to sleep, I am going to try it again, with the phono leads unplugged from the TT to confirm it is probably them picking up the interference. The phono leads run near power outlets, but it was worse before as they run directly past all the power outlets into the back of the AV.
No, the ticks came when the TT was switched off! It was as soon as the QED phonos were connected, hence the question as to whether either those cables are not suited for phono, or if there is a fault with them. Again I will try something, I will plug them into a different stereo input to see if they also do the same, I dont think they will.
Ok, I decided to both check what hum was present in my old configuration of TT -> AV amp, with the QED cables, and it was silent. With the P5 switched off. I was swapping headphones around, and noticed that the P5 switched on was causing my main speakers to hum even when it was not connected to anything - and picking it up and moving it away made no difference to the level of hum. I unplugged it and plugged it back into another socket across the room, and no interference even when the unit was moved next to the TT. If I connected up the TT to the P5 now the power was plugged in nowhere near the rest of the equipment, I still got similar levels of hum. The only thing I can think of therefore is that the power lead is causing some interference, if it were the psu within the P5 then I would have thought moving it away from the other components would have gradually lessened the hum. And the hum follows the P5 around when I hook the TT up to it, because it is tethered to that source. Now, the P5 is American, and came with the US 'kettle' lead, with 2 round prongs. I am using an adapter to convert to UK plug. Could THAT be causing the problem here?
Confirmed, I swapped over the lead with the one powering the TT and the hum was virtually inaudible at full volume, just some hissing. Having been googling this for the last hour or so, I am amazed this is not more well known or publicised. Anyone buying US audio equipment and using in the UK should be using a UK kettle lead, using an adapter will work for power, but introduce noise, especially noticeable for phono use! Now, will a high grade audiophile kettle lead we a worthwhile purchase!?
N No; you've sorted it out. Leave well enough alone. What is a P5? What table are you using? I don't recall seeing the make and model of any of this stuff, which doesn't help those who are reading and trying to offer help. Since you have the noise and hum gone, you know where things need to be connectd and with what cords. The only other bit of advice for you is that the leads from the turntable to the phono preamp should be as short as possible. If you need to run a longer cable set somewhere, run it between the preamp and the AVR. That will net you the absolute lowest noise connection. -Bill
Parasound Halo P5 pre-amp, as mentioned in the first post , the TT is a AT-LP5. The reason I asked about the better kettle lead is that there is still a very slight hum at max vol, but at normal listening volume there isnt any more.
Another development; so I went to find a UK kettle lead among my computer equipment, and found a previously unused one. Plugged it in and it was quieter than the US kettle lead I got with the P5, but the hum was noticeably louder than the kettle lead which came with my TT. Which kind of pushes me towards getting a 'audiophile' lead. Still odd that there isn't more about this on the net.
