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 Post subject: Hum issues
PostPosted: Thu Jul 06, 2017 7:08 pm 
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Joined: Fri Dec 27, 2013 7:46 pm
Posts: 44
Location: Surrey, BC, CA
Hi folks,

I am having troubles getting rid of hum in my system:( I am running a Mcintosh C48 pre amp connected to a Psvane TC5 integrated tube amplifier powering Focal Aria 936's. I am getting a constant lower hum tone that is only affected slightly by the volume knob on the Psvane. It is constant with all my sources and completely disappears when I disconnect my rca I/C (audio quest golden gate) from the Psvane.

I have used the C48 with a few SS amps and never had and noise at all. And when the Psvane is used on its own it is dead quiet. A fellow Cam'r suggested I may be dealing with an impedance issue and I should try my Rec out instead of my pre outs but I still got the hum. The Mac and the Psvane sound great together but whenever the music passages get quiet all I hear is that dam hum:(

So is it an impedance issue or does it sound like a ground loop issue? Any input would be much appreciated!

Here are the specs of my components:
C48
TOTAL HARMONIC DISTORTION
0.002%
FREQUENCY RESPONSE
+0, -0.5dB from 20Hz to 20,000Hz
+0, -3dB from 15Hz to 100,000Hz
MAXIMUM VOLTS OUT (BALANCED / UNBALANCED)
16/8 V RMS
INPUT IMPEDANCE (BALANCED / UNBALANCED)
44K ohm, 22K ohm
PHONO VOLTAGE GAIN
60dB
HIGH LEVEL VOLTAGE GAIN
15dB
SIGNAL TO NOISE RATIO
100dB
DUAL MONO POWER SUPPLY
No
DUAL MONO, FULLY BALANCED
No

Pavane TC5
Specifications:
 Input impedance: 100 kohm
 Input voltage: <=450mV
 Output power: 2 x85W
 Power consumption: 200 Watts
 Output impedance: 4 ohm and 8 ohm
 Frequency Response Range: 20 Hz to 20kHz
 THD: <=1.2%
 S/N Ratio: 88 dB
 Power supply: AC115V 50/60Hz +/-10% or 230V 50/60Hz by modification
 Fuse: 250V 8A slow blown for 115V or 250V 4A slow blown for 230V
 Netsize:161/8"Wx131/8"Dx81/4"H
 Net weight: 23kg / 51 lbs
 Vacuum tubes: 4 x KT120, 4 x 6SN7(6N8P), 1 x 6N9P
 Operating temperature: 0-40 Celsius
 Operating humidity: 20-80%
 Storage temperature: -20 to 70 Celsius
 Storage humidity: 20-90%


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 Post subject: Re: Hum issues
PostPosted: Thu Jul 06, 2017 7:46 pm 
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Joined: Sat Jan 11, 2014 12:47 pm
Posts: 27
Location: Montreal, QC, CA
could be lot of things, even your actual component..

Can you try using another preamp than the C48? just to see if it is the preamp feeding the hum to the psvane and not the psvane itself ?

If you suspect RCAs /ground could be the issue try this out,

http://www.jensen-transformers.com/product/ci-2rr/

ive had annoying hum and tried so many things, only thing that fixed it was that Jensen goodness! they go on ebay sometimes for almost half the retail price used...

worth a try


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 Post subject: Re: Hum issues
PostPosted: Thu Jul 06, 2017 8:23 pm 
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Joined: Fri Dec 27, 2013 7:46 pm
Posts: 44
Location: Surrey, BC, CA
f18inch wrote:
could be lot of things, even your actual component..

Can you try using another preamp than the C48? just to see if it is the preamp feeding the hum to the psvane and not the psvane itself ?

If you suspect RCAs /ground could be the issue try this out,

http://www.jensen-transformers.com/product/ci-2rr/

ive had annoying hum and tried so many things, only thing that fixed it was that Jensen goodness! they go on ebay sometimes for almost half the retail price used...

worth a try


Unfortunately I do not have any access to any other preamps. I will keep a eye out for one of those Jensens. It's definitely worth a shot!


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 Post subject: Re: Hum issues
PostPosted: Thu Jul 06, 2017 11:07 pm 
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Joined: Sat Aug 25, 2007 2:00 am
Posts: 1221
Location: Guelph, ON, CA
Are you connecting a preamp to the preamp side of the integrated? You normally hook up sources to preamps and preamps to power amps. Not usually preamps to integrated amps unless the integrated has "Main In" jacks. (My wife woke me up at 3am to take the dogs out so I hope I'm not groggily misreading your OP)


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 Post subject: Re: Hum issues
PostPosted: Fri Jul 07, 2017 5:38 am 
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Joined: Fri Jan 08, 2016 6:15 am
Posts: 64
Location: Kingston, ON, CA
I feel your pain - hum can be a really challenging thing to pin down and resolve.

I would suggest starting here:

PS Audio How-To

Scroll down the How-To list and you'll see a couple of excellent articles that talk about hum and how to isolate the issue so you can ultimately chase it out of your system... which isn't always possible, I will warn.

Report back after giving the How-To's a read.


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 Post subject: Re: Hum issues
PostPosted: Fri Jul 07, 2017 6:32 am 
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Joined: Fri Dec 27, 2013 7:46 pm
Posts: 44
Location: Surrey, BC, CA
noway wrote:
Are you connecting a preamp to the preamp side of the integrated? You normally hook up sources to preamps and preamps to power amps. Not usually preamps to integrated amps unless the integrated has "Main In" jacks. (My wife woke me up at 3am to take the dogs out so I hope I'm not groggily misreading your OP)


The psvane does not have main in jacks. I was told by the distributor that I could use it with a preamp. I was told to put the psvane volume at about 70% and control the volume with the c48.


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 Post subject: Re: Hum issues
PostPosted: Fri Jul 07, 2017 8:32 am 
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Joined: Fri Dec 27, 2013 7:46 pm
Posts: 44
Location: Surrey, BC, CA
bumperdoo wrote:
I feel your pain - hum can be a really challenging thing to pin down and resolve.

I would suggest starting here:

PS Audio How-To

Scroll down the How-To list and you'll see a couple of excellent articles that talk about hum and how to isolate the issue so you can ultimately chase it out of your system... which isn't always possible, I will warn.

Report back after giving the How-To's a read.


I did read that psaudio article and tried a few of the suggestions with out any success. I also read an article on audioholics and they recommended trying a Hum-X but that device seems a bit gimmicky.


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 Post subject: Re: Hum issues
PostPosted: Fri Jul 07, 2017 8:54 am 
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Joined: Thu Jan 13, 2011 11:29 am
Posts: 425
Location: St.Catharines, ON, CA
Could try a PEC (parallel earth conductor).
Heavy gauge wire(larger gauge than IC shield) between amp and preamp chassis.
Provides a lower impedance path for ground currents.

Gary


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Last edited by sasquatch on Fri Jul 07, 2017 8:58 am, edited 1 time in total.
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 Post subject: Re: Hum issues
PostPosted: Fri Jul 07, 2017 8:57 am 
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Joined: Thu Sep 30, 2010 9:28 am
Posts: 22
Location: Crossfield, AB, CA
Try setting Mac at 40% & use volume control on yer amp.


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 Post subject: Re: Hum issues
PostPosted: Fri Jul 07, 2017 9:48 am 
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Joined: Sat Aug 25, 2007 2:00 am
Posts: 1221
Location: Guelph, ON, CA
RayRay83 wrote:
noway wrote:
Are you connecting a preamp to the preamp side of the integrated? You normally hook up sources to preamps and preamps to power amps. Not usually preamps to integrated amps unless the integrated has "Main In" jacks. (My wife woke me up at 3am to take the dogs out so I hope I'm not groggily misreading your OP)


The psvane does not have main in jacks. I was told by the distributor that I could use it with a preamp. I was told to put the psvane volume at about 70% and control the volume with the c48.


I wouldn't do that myself in spite of what the distributer said (call McIntosh and see how they feel about using their preamp like that?) but if I was forced to and I got hum I would try different interconnects and see if that helped and if necessary experiment with different grounding schemes and gain settings.


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 Post subject: Re: Hum issues
PostPosted: Fri Jul 07, 2017 10:12 am 
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Joined: Fri Jan 08, 2016 6:15 am
Posts: 64
Location: Kingston, ON, CA
RayRay83 wrote:
I did read that psaudio article and tried a few of the suggestions with out any success.


Some systems just hum... sorry bud.

RayRay83 wrote:
I also read an article on audioholics and they recommended trying a Hum-X but that device seems a bit gimmicky.


Nor familiar with the Hum-X, but I have used the PS Audio version known as the Humbuster. It's an interesting device that can remove hum in certain situations - I've got one. Hard to find though.


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 Post subject: Re: Hum issues
PostPosted: Fri Jul 07, 2017 1:28 pm 
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Joined: Thu Aug 03, 2006 4:43 pm
Posts: 545
Location: Ottawa, ON, CA
Sadly, I suspect the solution to your problem is going to be sell the integrated amp, and buy a proper power amp...
The thing is, you have a pre-amp in the Mac amplifying the signal, then you reduce it with Mac's volume control. The you have the pre-amp in the psvane amplifying it back up again, only to be reduced by the psvane's volume control... You've got twice the noise and distortion adding amount of circuitry in the signal path then you need, and with (probably) more than twice the amount of gain you need. Hum and noise are going to be an issue with that sort of arrangement....


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 Post subject: Re: Hum issues
PostPosted: Fri Jul 07, 2017 5:32 pm 
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Joined: Fri Dec 27, 2013 7:46 pm
Posts: 44
Location: Surrey, BC, CA
dcrooks wrote:
Sadly, I suspect the solution to your problem is going to be sell the integrated amp, and buy a proper power amp...
The thing is, you have a pre-amp in the Mac amplifying the signal, then you reduce it with Mac's volume control. The you have the pre-amp in the psvane amplifying it back up again, only to be reduced by the psvane's volume control... You've got twice the noise and distortion adding amount of circuitry in the signal path then you need, and with (probably) more than twice the amount of gain you need. Hum and noise are going to be an issue with that sort of arrangement....


Yeah I completely agree with everything you have said it is the most likely thing I am dealing with. I do have have a couple of power amps but they do not sound nearly as good as the mac/psvane combo. They don't have the hum but they also don't have that wall of sound I get with the psvane.

I guess you'll see the Psvane up for trade/sale soon or I might look into having it modified to bypass the pre amp stage. Its a bit of a shame because I do enjoy both pieces of equipment very much.

Thanks
Ray


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 Post subject: Re: Hum issues
PostPosted: Fri Jul 07, 2017 6:42 pm 
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Joined: Tue Aug 24, 2010 9:19 pm
Posts: 43
Location: kamloops, BC, CA
I second the Jensen transformers I have been using them for a couple years. The would be worth a shot


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 Post subject: Re: Hum issues
PostPosted: Fri Jul 07, 2017 6:55 pm 
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Joined: Thu Aug 03, 2006 4:43 pm
Posts: 545
Location: Ottawa, ON, CA
RayRay83 wrote:
Yeah I completely agree with everything you have said it is the most likely thing I am dealing with. I do have have a couple of power amps but they do not sound nearly as good as the mac/psvane combo. They don't have the hum but they also don't have that wall of sound I get with the psvane.

Ya, I understand it when you get a sound you really like! So now the fun part is to find an amp, with the sound of the psvane, that you can run with your Mac. I'm sure there's something out there, it'll just take some experimentation to find it!

Good luck! Dave


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