Turntable Hum


Any help appreciated!

Low pitched hum coming from TT input ...even when TT is not running . Hum is noticeable at about 1/4 volume & really bad at 50%

Manley Monoblock Snappers

VPI Scout w Hana MC cart right next to amp on table (moved TT away from amp to floor made 0 difference)

Allnic 1202 Phonostage grounded to VPI TT (on floor below JBL speakers & main speakers right to the left Tekton Encores)

Manley Jumbo Shrimp Preamp

Klark Teknik 32 band EQ

All cables (interconnects) recently replaced - Mogami

 

I tried ground lifting the TT motor - no change

unplugged tv & nearby laptop - no change

unplugged all lights nearby - no change

 

I suppose my next troubleshooting venture is to run a ground from phonostage to everywhere & start touching things? Phonostage seems to be the culprit....

😕

 

Thanks everyone!

128x128tommypenngotti

@millercarbon tried different outlet on phonostage & preamp , no change ...

could the power cables for any of my units be malfunctioning causing this? I could swap...

@rauliruegas Turntable & phonostage are grounded 

 

@aberyclark tried different RCAs from TT to Phonostage , no change...

Power cords themselves won't cause this except that they are the path to ground. So lifting the ground on one or both is another test. Use a cheater plug to test this. Then if that doesn't work I would try the Allnic somewhere else, another system, anything at all just to rule it out. 

Solving puzzles over the internet is a PITA because things that would be freaking obvious in person come in dribs and drabs online. Like I just noticed you said "high buzzing comes from the right side of the turntable." What are you talking about? Please be careful to discern between mechanical vibrations you hear emanating from the physical device itself and hum or other noise that is in the electrical signal and so is only heard coming from the speakers.

I'll try your suggestions, the only time the hum goes away is when the phonostage is out of the loop 🤷‍♂️

If nothing is connected to the input of the phono preamp, does it still hum? If yes, based on the statement above the problem is the phono section, which might have to be serviced.

Building on Ralph’s diagnosis— you have tubes in the Manley. Have u checked the phonostage tubes?or tubes anywhere else in the signal path.   Perhaps microphonic?  

@millercarbon thanks..when I disconnected the RCAs from TT to Allnic & inputted 1 by 1 I noticed on the right input a slightly higher pitched buzzing , nothing major , just slight...electrical , emanating from speakers for sure..I'll try moveing the allnic to anotehr system & see if its noisy....Arent these Phonostages kinda inherently noisy because they are boosting the signal so much? 

@swanny76109 The Allnic 1202 Phonostage is almost brand new...I do notice when I tap on the cylindrcal tube cases I get a fair amount of feedback through the speakers ...noisy...thanks