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Ami B hum
Posted: Thu Oct 04, 2012 5:05 pm
by wingnut049
Hi Group (especially Ron and Rob) - I have an AMI B that's drving me nuts. There's a low hum only when a record is playing. As soon as the needle lifts off it stops. I've moved the ground wire to several spots and even removed it. That didn't work. I've replaced the 6L6 and 5U4 tubes. Still hums. I've just ordered a pair of 6N7 tubes. Will the 6N7's eliminate the hum? Any advice?
Re: Ami B hum
Posted: Thu Oct 04, 2012 5:33 pm
by ami-man
Do you think that there may be some form of rumble being picked up from the turntable or motor?
You say that the hum goes if the needle is removed. I would check the cable from the cartridge for any shorts etc and maybe try an input into the ampfifier from another source as a quick test.
I may be barking up the wrong tree because I have never worked on this mechanism.
Regards
Alan
Alan Hood
ami-man
UK
Re: Ami B hum
Posted: Thu Oct 04, 2012 6:09 pm
by wingnut049
Hi Alan - Never thought about that. Good idea. I'll give it a shot. Thanks.
Re: Ami B hum
Posted: Thu Oct 04, 2012 8:51 pm
by Ron Rich
Guy's,
It would be my guess that it is related to the tone arm -- either its picking up "rumble" from the motor( check motor supports!), or the tone arm needs grounding/"un-grounding"--- ("earthing" to you Alan) Ron Rich
Re: Ami B hum
Posted: Fri Oct 05, 2012 1:15 am
by wingnut049
Hi Ron - I moved the ground wire to different spots on the box to ground and then completely removed it. No difference. I'm beginning to think Alan may be right. There isn't much else it can be.
Re: Ami B hum
Posted: Fri Oct 05, 2012 1:29 am
by Ron Rich
I think so also---did you dis-connect the tone arm wire at the amp--
If no hum then--it's picking up rumble from the TT--Did you check the motor mounts ? Ron Rich
Re: Ami B hum
Posted: Fri Oct 05, 2012 1:39 pm
by DoghouseRiley
This problem of picking up a background noise caused by turntable motor vibration due to hardened motor mounts is pretty common, I had it with one of my Rock-Olas, but the plus side is that they are easy to change and cost little.
A "test" is to put your finger lightly on the tip of the gripper arm whilst a record is playing to see if you can feel the vibration.
Of course you problem is not necessarily this but it's worth changing the grommets anyway.
Re: Ami B hum
Posted: Fri Oct 05, 2012 8:15 pm
by wingnut049
I bought the B from Freddy Bailey who restored it. It just ocurred to me that there's a dime stuck in between the cartridge and the tone arm (I'm assuming for added weight). Could this be the culprit?
Re: Ami B hum
Posted: Fri Oct 05, 2012 8:23 pm
by wingnut049
Eurika!! It's the wire from the cart to the amp. I took the dime out and it still hummed. I just touched the wire and the hum stopped. YEA!
Re: Ami B hum
Posted: Fri Oct 05, 2012 10:29 pm
by Ron Rich
Funny-don't understand why you mentioned it, but I was just thinking of Freddy--have you seen/heard from him lately ?
Ron Rich
Re: Ami B hum
Posted: Sat Oct 06, 2012 8:33 am
by ami-man
Hi Ron,
I used to buy video games off of Freddy in the early 80's when he had a company called Gameworld in the UK.
Regards
Alan
Alan Hood
ami-man
UK
Re: Ami B hum
Posted: Tue Oct 09, 2012 9:51 pm
by wingnut049
Haven't heard or seen anything of Freddy for several years. He took down his website and I can't find any information. Don't think he went back to England.
Re: Ami B hum
Posted: Wed Oct 10, 2012 6:54 pm
by Ron Rich
Last I heard, he was in England--maybe 2-3 years ago--my memory does not work too well, on "past time"--
Ron Rich
Re: Ami B hum
Posted: Thu Oct 11, 2012 2:28 pm
by ami-man
Hi Guy's
The last time I saw any information for Freddie: he was still on your side of the pond, orhe was in June of this year.
Regards
Alan
Alan Hood
ami-man
UK
Re: Ami B hum
Posted: Tue Oct 30, 2012 4:32 pm
by wingnut049
SON OF AMI B HUM - Still have the annoying hum. The tonearm wire has no breaks, all the tubes have been replaced, and the ground wire doesn't seem to make a difference. I contacted Denny at Victory Glass and he suggested switching the leads off of the cartridge which I did with no results. I'm going to order motor grommets and hope that the problem is solved. Other than that I don't know what else to do.