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New TT new hum


Harleywood

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It's not uncommon to have a bad cartridge and this is what sounds like is going on and why you only have it in the right channel now. Before you had the noise in both channels and you moved the tone arm wiring to the cart or something and the noise vanished in the left but stayed in the right. You might want to get a magnifying glass and take a very close look at all the connections to see if it's something you can fix. If no luck doing that you very well could have just got a bad cartridge that has an intermittent issue with the coil magnet wire, it's so insanely thin you wouldn't believe it.

 

Time to contact the seller is my vote also as it appears you do not have a ground loop problem.

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5 hours ago, babadono said:

It is certainly sounding like there is something wrong with the new TT like others have posted. Or the cartridge as you have stated. Anyway to try the cartridge from the old TT on this new one? Are they both MM or MC?

Have not swapped carts yet. Going to local shop tomorrow to pick up a new headshell so I can swap between the two without having to align cart again each time. 

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I'd like to thank everyone for offering up ideas. Good stuff here. This whole thing has me flustered and I  don't think I mentioned what got me to where I'm at so....

 

The sl1200gr is brand new from Best Buy. Don't ask I got lucky one day and the add to cart option was there so I did and four days later it was at the door. 

As of right now the TT is plugged into its own wall outlet using the three prong plug with the small ground wire running from TT ground lug to the amps built in phono stage ground lug. The Amp has a two prong plug as does the sub so both of those are plugged into a power strip from a different wall outlet located 8 feet away. Same circuit breaker I'm sure. This gives me least amount of buzz and only in right channel. Ground lift the TT power cord with a cheater and that yields the same result. I've plugged the A/C cords in every imaginable way and this setup is the quietest and any other combination results in very loud buzz at low volume especially when the amp and TT share an a/c outlet or strip. I've tried three pairs of RCA cables as well and moved my amp down in the rack so there's an empty shelf between amp and TT. I'm at a loss.

Going to get an extra headshell tomorrow so I can mount the old cart and try that. The way I'm feeling though I might just lug the whole table up to his shop so we can verify it either is or isn't the table using his system.  I'll keep y"all posted. Thanks again guys. 

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16 minutes ago, Harleywood said:

As of right now the TT is plugged into its own wall outlet using the three prong plug with the small ground wire running from TT ground lug to the amps built in phono stage ground lug. The Amp has a two prong plug as does the sub so both of those are plugged into a power strip from a different wall outlet located 8 feet away. Same circuit breaker I'm sure.

 

Fingers crossed for you!

 

That the R/L channels have different amounts of hum suggests it's not grounding issue .  ..Still, I would - as a matter of good TT hygiene - ensure that the TT/AMP/Pre are ALL plugged into the same outlet.  That the outlets are part of the same circuit may not be enough.  My TT hummed even though all outlets were (of course) part of the same circuit.  ...Only when they were plugged into the same 4-way receptacle did the hum disappear.  Maybe a more experienced member can explain why this should matter.

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When you pop the headshell off you can check it with multimeter.

 

Measure resistance between white and blue (left channel) then green and red (right channel).  You should get a DCR of around 800 ohms. This will rule out the headshell wiring and cartridge coils and point the problem in the direction of the wiring through tone arm and down to the left output RCA connector. Which you can also check by measuring the same connections from the end of the tone arm where the headshell connects to and the RCA out jacks. The sleeve is - and tip is + for the jacks. This last test you don't measure between the two colors, you need to check each wire individually for continuity. Example, white wire at headshell connector to tip of left RCA jack and blue to the sleeve of the left RCA jack. Repeat for the other channel.

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A search brought up a thread from 2005 in the Technical/Modifications section, started by Dr. Bill.  On September 16th, 2005, Dr. Bill posted:

 

"With the phono leads unhooked from the preamp, do you get hum?  If so, it is a preamp problem.  But if it only hums when the phono cables are attached to the preamp, it would have to be the TT, cartridge, or cables."

 

That sounded pretty decisive, so I thought it might be useful.

 

Here's the link to the thread:

 

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15 hours ago, captainbeefheart said:

When you pop the headshell off you can check it with multimeter.

 

Measure resistance between white and blue (left channel) then green and red (right channel).  You should get a DCR of around 800 ohms. This will rule out the headshell wiring and cartridge coils and point the problem in the direction of the wiring through tone arm and down to the left output RCA connector. Which you can also check by measuring the same connections from the end of the tone arm where the headshell connects to and the RCA out jacks. The sleeve is - and tip is + for the jacks. This last test you don't measure between the two colors, you need to check each wire individually for continuity. Example, white wire at headshell connector to tip of left RCA jack and blue to the sleeve of the left RCA jack. Repeat for the other channel.

Good information to have. Thank you!

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Update. TT was dead quiet in the local shops system. Kevin and Sound Exchange in Houston are the best. He loaned me a headshell and cart to bring home and try and that solved the buzz in my system. So it's either cart or headshell that my system doesn't like. Im guessing cart.  So relieved it's nothing major with the table. Heading back up to the shop to purchase new headshell. Boy, what an introduction into Technics and in general good turntables. 

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New $29 AT headshell with the new VM750sh cart, dead quiet. Technics headshell that came with table with old Ortofon cart, dead quiet. I guess the VM cart did not like the Technics headshell. It will remain a mystery. 

 

Big shout out to all of you! Always get good advice here. Appreciate all of you. Will post video of table up and running when I have time. Thanks again!!

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Virgin run with headshell tool yielded so so results with the new shibata stylus. No skips or tracking errors accross four LPs played just some groove distortion and pretty sure that can be fixed with a better cart alignment. My eyes aren't the greatest so going to pick up a lighted magnifying glass to help me see better. Thinking of buying a protractor as well. Any recommendations for one? Looking at the DB Systems protractor. I like that one only because it's not paper and I don't have to punch a hole in the spindle location which in my opinion leaves room for many errors. 20220318_225358.thumb.jpg.b831e5b47dfe1a3ed56ad0e0f6df4daf.jpg

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On 3/16/2022 at 5:05 PM, Harleywood said:

New $29 AT headshell with the new VM750sh cart, dead quiet. Technics headshell that came with table with old Ortofon cart, dead quiet. I guess the VM cart did not like the Technics headshell. It will remain a mystery.

 

the Mystery  could be the Technics Headshell lead wires  , since they connect  into the Tonearm wiring 

 

the TT is under Warranty ,  Technics should send you a New Headshell  replacement ,   no reason why a 30-40 $ Technics Headshell would have such issues , while there is nothing wrong with the VM750sh AT phono cartridge or the AT Stylus -

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Update,

Ordered a 4x lighted magnifier on a stand and I had missed the overhang using the jig by a longshot on the initial setup. Corrected that with a big improvement in sound but still seemed it was  lacking full soundstage. Played with VTF first and settled on 1.92g for now, 2.0g recommended.  A little better. The big improvement came with VTA. The vm750 cart is 17.3mm tall with a tracking angle of 23⁰ not the usual 22⁰. The chart in manual says set VTA dail to "0" since that is the minimum cart height without modifications.  Arm was still not level and still to high in back. Bass was very broad and open not tight and punchy like it should be so I added a 3mm thick leather mat on top of the stock rubber and wow, there's an orchestra under all that and all the instruments fell into their proper place with correct VTA.  That's the warmth and soundstage the Shibata is known for. 

I had to work at the setup compared to my previous tables but  the effort is definitely worth the reward. I have to say the Technics jig is pretty good. It sounds good. Can it be better? I'm about to start that endeavor and so begins the perpetual tweak, In Search of the Lost Chord. 

Screenshot_20220326-115018_Gallery.thumb.jpg.b85c4a489474500e5b8105c91cb97d5c.jpg

 

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