Vintage Amp buzz help please...

bloodiedathame

bloodiedathame

bloodiedathame

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I have a Creek CAS4040 hooked up to Kef Q35s with the following:

1) Disc input: Rega Planar 3 with RB250 tonearm
2) Tuner input: My PC via lineout from Steelseries Wireless Receiver
3) Aux/CD input: A Pioneer PDM550 6 disc player

I get really bad hum noise on from my TT and from my PC, but none from my CD player.
What's weird is that the Disc/TT noise is uniform and gets louder as you crank the volume. I think the tonearm should have an earth but it currently doesn't have one. So maybe that's the solution for that.

As for the PC, the noise is apparent with the volume down at 7 o clock position. When turned up to about 10 o clock on the dial, the noise goes away, and then comes back getting louder all the way to max volume at 5 o clock position. I can also hear the CD output very faintly when Tuner/PC is selected with a CD playing. I get the same noise any symptoms from the PC even with the minijack going straight to the soundcard.

Is it time to scrap the amp for something a bit more modern? Any help would be gratefully recieved.
 
Possible mains hum? Do you get it with the pc disconnected? Is the amp running from the same mains outlet as the pc? The rega tone arm is grounded through the RCA plug, so unless it's modified you won't have a external ground lead.

Your cd player bleeding through is just crosstalk and quite common.
 
Thanks for your reply.

I just tested out a few things.

The pc and monitors are on an extension from one output of the double socket, all the hifi stuff runs off an extension on the other output of the double socket. PC off or on makes no difference to the hum on the disc input.

I did try the TT in another socket on the same outlet, same hum, and a socket in a completely different room. Same hum. When the TT is disconnected/unplugged the hum is much quieter.

As for the PC on the tuner input, when the mini Jack is disconnected I get a big hum. When I move my mouse I get an audible noise from the speakers. If I completely shut down my machine the high pitched hum goes and I only get a deep hum with the volume past 12o clock on the amp.

As the machine boots there's no high hum, then as it boots to windows and it loads up drivers etc the high pitched noise starts up again!
 
Have you tried setting the separates in a different room, on a different ring, completely isolated from your pc (unplugged from wall) to see if you still have issues? It's a ballache but it would help rule out ground issues. Also try a different extension lead.

Try setting your system up just cd amp speakers in a different room just to rule out dodgy grounding, see if you get noise with just the amp connected to the speakers no sources. Turntable noise can be mains hum, airborne interference or just a knackered cart. So a bit more of a pig to figure out, what cart are you using out of curiosity and has the amp ever been serviced?

The noise you experience with your pc running is RFI. The main reason lots of people go with external DACs instead of using onboard sound.
 
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gitbags said:
Have you tried setting the separates in a different room, on a different ring, completely isolated from your pc (unplugged from wall) to see if you still have issues? It's a ballache but it would help rule out ground issues. Also try a different extension lead.

Try setting your system up just cd amp speakers in a different room just to rule out dodgy grounding, see if you get noise with just the amp connected to the speakers no sources. Turntable noise can be mains hum, airborne interference or just a knackered cart. So a bit more of a pig to figure out, what cart are you using out of curiosity and has the amp ever been serviced?

The noise you experience with your pc running is RFI. The main reason lots of people go with external DACs instead of using onboard sound.
Click to expand...

I'll give it a go when I've got a bit of spare time as it's a fairly large operation.

Cartridge is a audio technica of some sort which is fairly new.
Amp has never been professionally serviced as far as I know but I replaced most of the fuses on it about 5 years ago when I got it.

I figured my USB Steelseries Wireless Receiver (that has a line out) was effectively a DAC but I figured it's still connected via USB to the motherboard so that could be why I get the same interference as I do when I mini jack from the mobo itself.

Andrew_McP said:
When faced with a similar issues plugging in a radio/CD player into my ancient Cambridge Audio amp, I gambled on one of these...
https://www.ebay.co.uk/itm/Ground-l...ound-System-/333306908036?hash=item4d9aa3cd84
...and it seemed to work. I am no electronics expert, and I wouldn't notice if it's degrading the signal as well as stripping the hum, but... well, something similar might be worth a go.
Click to expand...

I'll give that a go for the PC before I rip everything out! I might invest in some better multiways too as the ones I think are from Ikea.
 
bloodiedathame said:
I'll give it a go when I've got a bit of spare time as it's a fairly large operation.

Cartridge is a audio technica of some sort which is fairly new.
Amp has never been professionally serviced as far as I know but I replaced most of the fuses on it about 5 years ago when I got it.

I figured my USB Steelseries Wireless Receiver (that has a line out) was effectively a DAC but I figured it's still connected via USB to the motherboard so that could be why I get the same interference as I do when I mini jack from the mobo itself.



I'll give that a go for the PC before I rip everything out! I might invest in some better multiways too as the ones I think are from Ikea.
Click to expand...

Yeah unfortunately when dealing with hum and noise with separates it can become a big job swapping out cables and moving stuff about.

If the cart is new and a AT it should be fine, as for your amp it could probably do with recapping due to its age. But that's up to you whether you feel it's worth the money.

Fingers crossed you sort it all out.
 
I had a brainwave, the dac has an optical out so I've got a box that will do optical to phono. Hoping that will resolve the high pitched noise from the pc.

*Yup this worked.

Now to fix the TT buzz...
 
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Does your tt and amp have a ground terminal as you may need to use it. I’ve just added a Rega MM to my system- Cyrus 6xpd and Audio Technica Lp5 and that had started humming whdn it never used to. I ordered a ground cable and it seems to have worked so far
 
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