the home of the turntable

Hum from 1960 Electrohome Hi-Fi fitted with Garrard RC 88 TT

radio, tape, stands and accessories

Hum from 1960 Electrohome Hi-Fi fitted with Garrard RC 88 TT

Postby Beninski » 10 Jul 2010 01:30

Can anyone give me advice on the following. I recently purchased a 1959/60 Electrohome Hi-Fi console fitted with a Garrard RC 88 record changer. After some work, I restored the changer unit to decent working order. The issue I have is a hum that increases when turning up the bass. I don't get this hum when I hook up a tape or CD player to the inputs on the back, just with the record changer. To me it doesn't sound like a problem with the tubes or transformer but more of a grounding issue with the TT. This TT and amp don't seem to have ground wire receptacles. Do any of you have any ideas or suggestions about this. It is a beautiful unit made of solid wood (no press, particleboard or plywood here). I love everthing about it except for that hum. Please advise.
Regards,
Mark[/url]
User avatar
Beninski
member
member
 
Posts: 26
Images: 16
Joined: 08 Jan 2008 18:07
Location: Wallaceburg, Ontario, Canada

Postby pirca » 10 Jul 2010 02:31

:arrow:
You do not say if you use a MM or other type of cartridge. This can be important.
Please, put a wire from turntable "mass" (Any Iron metal part. Ideal of motor), to amplifier "mass" (Any Iron metal part of chassis).
Now, the Hum must disappear.
If not, then the arm wires are faulty and it must be "rewired".
pirca
 

Postby aardvarkash10 » 10 Jul 2010 02:57

further to pirca's q on the cart type, some carts are highly susceptible to EMF from the rest of the set-up. Also, phono side is VERY dependant on good quality filtering in hte power supply. A 1960's console (presumably valve based) will have a dodgy power supply from new - at 50 years old now, its practically lethal unless you have upgraded it.

Bass implies low frequency. Probably at 2x the line frequency yes? If so, start with the power supply...
User avatar
aardvarkash10
long player
long player
 
Posts: 1157
Images: 24
Joined: 24 Mar 2009 02:57
Location: Auckland, New Zealand

New Zealand

Postby sreten » 10 Jul 2010 17:16

Hi,

Hum increasing with turning up the bass is a fact of life with valve equipment.

If all inputs have some hum due to less than ideal power supply filtering
then it will be worst on the higher gain turntable input, compared to line
inputs. It could be power supply capacitors need replacing.
If this is the case disconnect the turntable, the pick up input will
still have the most hum, so its fairly easy to diagnose this case.

Hum from bad wiring is usually terrible rather than just annnoying.
Note that too much grounding can cause hum due to ground loops,
this usually does not sound as bad as no proper grounding at all.

The causes from a turntable can be myriad, mechanical or electrical,
e.g. mechanical motor hum can be sonically picked up by the cartridge,
poor shielding of the motor field can be picked up by average wiring.

But check your grounding and try and make sure you have a star system,
this star system should connect to the amplifier at the ground point of the
systems most sensitive input.

/Sreten.
sreten
 

Postby wintermute » 12 Jul 2010 19:10

Bad caps, most likely in the pre amp stage if the only hum is when you mess with the bass.

Contrary to the previous post, my tube amps, having been recapped exhibit no hum whatsoever.
User avatar
wintermute
senior member
senior member
 
Posts: 771
Images: 2
Joined: 09 Nov 2002 04:48
Location: Ajax, Ont

Postby sreten » 13 Jul 2010 06:17

Hi,

Allright, what I actually meant is its a fact of life with original typical
valve stuff, e.g. consoles / radios, not really good hifi equipment.

:wink:/Sreten.
sreten
 

Postby wintermute » 27 Jul 2010 18:25

Old unrestored stuff yea... But any tube gear, good or bad, with bad caps will hum...
User avatar
wintermute
senior member
senior member
 
Posts: 771
Images: 2
Joined: 09 Nov 2002 04:48
Location: Ajax, Ont

Return to Other Stuff


Design and Content © Vinyl Engine 2002-2014

faq | site policy | advertising