Ok, so when I had my Onkyo Amp and pre amp connected, I had a hum in the Right Chanel. This is the same Onkyo Amp where I ended up burning the transistor and fuse because I was trying to eliminate this Hum issue.
It sounds like Vooohhhh. and it is constant.
I thought it was the Amplifier.
Now I have a Mitsubishi amp connected to a phase linear pre-amp and a separate tuner. The Left Chanel is clean and has no hum noise, when I switch the speaker wire (same speaker & wire) to the Right side I get that same hum again I was getting in the other setup.
This same hum was happening when I lived in a different city.
I don't understand what or why this is happening. I replaced components, wires, speakers, outlets where the components are plugged. I plugged everything into one power strip, different strips, into the back of the pre-amp and made no difference.
Why do I keep getting this hum in the R side Only ?
It is driving me nuts and don't know how to get rid of it. I grounded the system every which way, it made no difference.
Is this an XLR, or RCA setup? I've had both make a lot of noise. You've swapped everything out and you still have the noise? Speakers? Speaker wire (cable)? Power amp? Preamp?
I see you changed wire. Which wire, (cable) did you swap? How cheap is the cable? It's not to cheap or to long...
RCAs and XLRs the only thing I see you haven't mentioned..
I realize you have done a lot of stuff to find your problem, never the less if you haven't already done this I would highly recommend it. The easiest way to source a hum is to disconnect all of your sources from your amp. Turn the amp on - any hum? If not, then connect your next source to the amp. Any hum? Etc. When it starts to hum you have identified the source, now you can more easily solve your problem. The problem could be in the source itself or in its connectivity (wires, wire distribution etc.)
Without a speaker connected to the right side of the pre amp there is no hum. The hum does not come on by turning the amp or pre amp on if there is no speaker connected.
It is not the speaker because I tried different spekrs and wires. It is not the equipment because I tried different setup/equipment and still have the hum in the R. side.
Following up on my post, your speakers should be connected when you start with my suggestion.
1) First connect ONLY the amp and speakers. Turn on. No hum then on to step 2)
2) Add pre-amp with no sources connected, such as your tuner, phono, etc, connected do the pre-amp. Turn on. No hum then add your sources, one at a time, starting with the tuner. You should find a hum in one of these sources. Just a WAG, but I suspect you have a tuner with a bummer R channel.
Plugged pre amp and attached it to Amp. When I turned on the pre-amp the hum is back.
All is plugged into the same power strip.
My understanding is that I would not get a hum anyway by just plugging in the Amp since it needs a pre-amp to do anything.
So I doubt it is the pr-amp that is causing the hum.
Again...I was using a different pre-amp and amp before and I was still getting the SAME hum in the Right side....no matter what speaker or wire I used.
Have you tried using a ’cheater’ plug on the end of the preamp power cord? Some times it is good to have only one plug with the ground (on the amp cord) - the rest of the stuff benefits from that ground. It is safe, if not preferable, to use the cheater plug on the pre-amp (if that works) until you can source the ground issue causing (if it is) your hum.
Although I don’t think your problem is the power strip, to rule out one more possibility, you might plug them into separate outlets and see what happens. Another thing to consider is the placement of power cords and IC’s. If you can, be sure that they are not close to each other and if they must cross do so as close to crossing at a right angle.
And if you have used the same IC’s with all of your stuff make sure you have IC’s which are properly constructed to reject EMI. I had a right channel hum once that was the result of one IC passing too close to a transformer. (I recently saw a diagram of a Canary IC, LV-77s on Blue Jeans site which shows a high quality insulation/reject of EMI which is used in their own audio cables)
FWIW, there is no easy fix for your problem, I think. Since you have used different amps and preamps with identical results its got to be some where in the electronics preceding the preamp.
By the way None of these components have a 3 prong plugs. They all have 2 prong AC plugs. There is a Ground screw on the back of the pre-amp. Grounding it is making no difference.
IC’s (short for interconnects) are what you refer to as ’wires’. There are low quality ones (thin, uninsulated, and cheap - usually furnished with inexpensive audio/vidio components) and much better quality and insulated ones. This could easily be your problem (or not). I really have nothing further to offer you at this time except for kind wishes.
Ho Customersfirst, You mentioned that you changed all the wires etc. Did you mean that you changed them with same but new cables (wires)? Or are the cables the same original ones but swapped around? Are the speaker cables terminated with plugs or just bare wire? I noted the that you swapped the interconnect (IC) between the preamp and amp and heard that the hum followed. I am giving thought to this. It appears to me that (a possibility), one of your sources could be damaging the preamp. You did say that you bought a new amp and pre. Until later 🇦🇺
The hum could (I stress could) be damage caused by a source to the preamp. You mentioned that you changed the preamp and amp to new ones but nothing else. It seems unlikely to be cables after your experimenting, so, if the preamp has the same (right) channel damage as before in your old Onkyo, I would suggest that a source (same as connected to the Onkyo) is causing damage to the preamp. Have you connected the same original sources to the same inputs as you had them in the Onkyo? Obviously the turntable will be connected to phono. Other A’gon contributors with better electrical experience than myself might chime in here, but I was thinking that a source might be causing damage to the right channel of the preamp. 🇦🇺
Further to that thought, could a speaker feedback or amp feedback to the preamp be causing the hum? If you search this forum you will see various views on ac regeneration and batteries etc. Worth reading when you get too frustrated! 🇦🇺
Find out if there are any fuses In the circuits inside the amps or preamps, not in the main back. If so you may have one out in the preamp. I got a hum in my right channel last week. I’m running BAT monos each amp has 4 fuses, one was out in one amp. Change fuse no more hum.
Cold solder joints of Amplifier might cause a 50-60Hz hum.
If after all of the suggestions here are exhausted, with the amplifier unplugged and cooled down, carefully with a multi-meter check the resistance on the left side and right side channel inputs. Between signal and grounds, dry solder or cold solder joints can create hum issues. You could also Ohm it out, check resistance between the input contact and the solder joint on the next solder joint past where the connector is soldered to ensure continuity, and also Ohm to ground. I only suggest inputs because they are physically stressed by installing and removal of connectors.
This isn't fun, it takes a bit of time to pull it down and check it. I am only suggesting the input as it's easier than say a filter cap, or one along signal path. Do you know if it has a separate power supply for each channel in the amplifier?
This is all becoming too confusing and hard to follow.
Let me state (To simplify this hopefully) how this all started and where I am now:
I started out connecting an Onkyo large Amp and matching pre-amp. Had a hum in the R side. Grounded it every which way, sometimes it is better than others but the hum is never gone.
I noticed the Phono stage on the Pre-amp is often faint or fades away.
So I replaced the Onkyo pre with a Phase linear pre. I still have the hum.
So I removed the Onkyo Amp and replaced it with a Mitsubishi Amp. The hum is still there (NO matter what source or NO source).
This is also true with the Original set up (ALL Onkyo)
So just now, I did the following:
To complicate things further or maybe not:
I removed the Phase linear pre amp and connected the Onkyo pre amp instead. Connected to the Mitsubishi amp. I also connected a Tuner as a source.
The hum is gone but the Onkyo pre amp has issues with the phono stage and the L, R, Mono switch....as I mentioned above. I have cleaned the switches with the spray but the issue is not resolved.
And when I had the Onkyo amp connected to it I had the same hum issue.
So what does this mean ??
I guess the Phase Linear pre amp is causing a Hum ?
And the Onkyo Amplifier is also causing a hum ?
And I need to fix the Onkyo Pre-amp as a Minimum and maybe the Onkyo Amp if the hum doesn't go away.
Ok, I hope things are clearer now.
So I tried these different setups:
1- All Onkyo (Amp, pre-amp). Hum in R. side.
2- Onkyo Amp, Phase Linear pre-amp. Hum in R. side.
3- Mitsubishi Amp. Phase linear pre-amp. Hum in R. side.
4- Mitsubishi Amp. Onkyo pre-amp. Hum is gone. But there are the issues with the pre-amp that I stated.
I eliminated the signal source (Tuner) since it is not the issue here.
All cables and speakers were changed so those are not the issue either.
What are the odds that the Onkyo amp and P. Linear pre-amp needs repair in addition to the repairs needed on the Onkyo pre-amp ??
And would any of this cause the Hum ? I don't understand.
Hey Customerfirst, it would seem you have tested all the configurations. Your conclusion would seem unlikely, but possible. BOTH preamps with problems?
What models are the amp/preamps? How old are they?
I would also agree with rixthetrick that there may be a dry joint or component failing in each (you need to be unlucky).
If you were talking about some sort of room treatment of a dubious source, you might attract more notice and help.
If I can think of anything further I’ll pop my head in and see how you are doing. Good luck from me. 🇦🇺
Do you have a competent electronics repair service in your area, especially a service agent for reputable hifi brands? Perhaps you could get on Google and look for one, especially if you're in a highly populated area.
A good service agent should be able to with the correct tools identify the problem and give you ideas on costing to repair the device/s
Step 1: identify the culprit by a process of elimination.
If you swop the IC's from the source to the preamp over, does the hum change sides, or stay the same. If it stays the same, it's not the source.
Restore source to normal, and swop IC's over from preamp to amp. If the hum changes sides, it's the preamp, if it doesn't, it's not.
Restore IC's to correct positions. Swop speaker cables over. If the hum changes sides, it's the amp, if not then, well, it must be the speaker.
Step 2: experiment with different grounding of electrical supply to guilty component, dressing of cables, etc. etc. If nothing works, it's internal, and yes, you need to seek out a repair person.
Interconnects from CD-player/DAC/phono amp, whatever the source is. Leave the interconnects as they normally are at the source end, but change over L to R and R to L at the preamp end. Audition. Has the hum changed sides or not?
If not, continue on down the line, doing this same experiment at each stage of the chain. source-->preamp; preamp-->power amp; power amp-->speakers. If the hum changes sides at any point in this experiment, it's the component providing the signal at that point that's at fault.
If it never changes sides, you're SOL and need more expert help.
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