What have I done?

[Davros59]

Ok, so here's the story so far. Pain and suffering follows. Audiophiles enter with caution.

Had a few vinyl LPs lying around and no working TT so as a gentle reintroduction picked up a decent deal on an Audio Technica LP-120 because I loved the Technics 1200 in the day and decided this would be a good start. Mmmmm I hear you saying, very suspect choice. So yes, the direct drive rumbles and it has some functions a DJ might find "sick" (sorry, I promise not to regress ever again) but for my listening it sucks (ok, that was the last).

Fine I said, decision was a poor one but how can I move forward? New cartridge! Couldn't afford anything flash so picked up a reasonably priced AT440. To my ear, a definite improvement so I'm heading in the right direction.

Then I read about a modification someone had carried out on their LP-120 by removing the dreaded internal phono amp. Scratching my head I said to myself, phono amp? What's that? Anyone laughing at this stage can leave the room please. Time for a bit of research. Better late than never right? Eventually there was a dim light starting to dawn. I proceeded with the mod because I believed I had a really viable alternative. In fact 2! A Proton D540 which I am emotionally attached to and a Harman Kardom PM655 with what appeared to be a really nice big phono stage. Bigger is better right? The light is still very dim at this stage but don't laugh yet.

Ok, proceeding I ripped out the Audio Technica phono amp. Haha, take that you cheap imposter! I held it up to the light like I had just pulled Excalibur from the stone. I carefully attached the little delicate wires coming from the cartridge directly to a pair of bear RCA cable ends. The excitement was really intense, small victory coming. I put it all back together and plugged it in, and in stupendous anticipation poised my finger on the amplifier go button ready for Nirvana. Nothing. Oh dear. Thinking. Homer moment. I plugged into one amp and turned on another. Everyone does that right? This time for sure, turned it on and the low level buzzing blistered my ears. Quickly turning that off I decided to watch all of the instructional video. Oh, I may need an Earth connection? Why? It didn't have one before I made the modification? Fine, fine, pulled it all apart and connected a small wire very neatly to the exact spot mentioned, routed it out of the unit and put it all back together. Here we go. Finger poised. Silence! Sweet, sweet silence. Now for the real litmus test, a record. Even better, sounds similar to popular music emanating from my speakers with no discernible buzz or unnecessary squeak. Happier at this stage.

After a few days of listening I thought I'd try the original cartridge. can't hurt right? AT440 out, ohhhhhh ummmm forgot to turn off the amp and caused a really (no, seriously) loud and not pleasant sounding thump and BUZZ (bigger than before). I stood slightly comatose for a moment. Ok, retrace my steps and put the cartridge back. What idiot makes the same mistake twice right? Amp was still on. Corresponding thumb and BUZZ. No, sorry, reverse order, BUZZ and then thump this time.

I'm the first to admit my diagnostic skills are in need of improvement.

Now I have a constant buzzing. I'm intensely unhappy at this stage. I turned everything off. Counted to ten and then turned everything back on. Still buzzing. Really not a nice buzz either. Bees buzz very pleasantly, almost dolefully, but this was anything but. I took a deep breath and removed the Earth wire. The buzzing stopped. Everything quiet and very peaceful. Litmus test, record on. Nice sounds, no buzz, no squeak. Or squawk. I'm a genius I proclaimed.

Genius aside. What exactly happened? Why and how is this remotely possible?

I have many more perplexing questions to ask the broader and perhaps smarter Stereonet public, but let's start here.

[lovetube]

Ok, so here's the story so far. Pain and suffering follows. Audiophiles enter with caution.

Had a few vinyl LPs lying around and no working TT so as a gentle reintroduction picked up a decent deal on an Audio Technica LP-120 because I loved the Technics 1200 in the day and decided this would be a good start. Mmmmm I hear you saying, very suspect choice. So yes, the direct drive rumbles and it has some functions a DJ might find "sick" (sorry, I promise not to regress ever again) but for my listening it sucks (ok, that was the last).

Fine I said, decision was a poor one but how can I move forward? New cartridge! Couldn't afford anything flash so picked up a reasonably priced AT440. To my ear, a definite improvement so I'm heading in the right direction.

Then I read about a modification someone had carried out on their LP-120 by removing the dreaded internal phono amp. Scratching my head I said to myself, phono amp? What's that? Anyone laughing at this stage can leave the room please. Time for a bit of research. Better late than never right? Eventually there was a dim light starting to dawn. I proceeded with the mod because I believed I had a really viable alternative. In fact 2! A Proton D540 which I am emotionally attached to and a Harman Kardom PM655 with what appeared to be a really nice big phono stage. Bigger is better right? The light is still very dim at this stage but don't laugh yet.

Ok, proceeding I ripped out the Audio Technica phono amp. Haha, take that you cheap imposter! I held it up to the light like I had just pulled Excalibur from the stone. I carefully attached the little delicate wires coming from the cartridge directly to a pair of bear RCA cable ends. The excitement was really intense, small victory coming. I put it all back together and plugged it in, and in stupendous anticipation poised my finger on the amplifier go button ready for Nirvana. Nothing. Oh dear. Thinking. Homer moment. I plugged into one amp and turned on another. Everyone does that right? This time for sure, turned it on and the low level buzzing blistered my ears. Quickly turning that off I decided to watch all of the instructional video. Oh, I may need an Earth connection? Why? It didn't have one before I made the modification? Fine, fine, pulled it all apart and connected a small wire very neatly to the exact spot mentioned, routed it out of the unit and put it all back together. Here we go. Finger poised. Silence! Sweet, sweet silence. Now for the real litmus test, a record. Even better, sounds similar to popular music emanating from my speakers with no discernible buzz or unnecessary squeak. Happier at this stage.

After a few days of listening I thought I'd try the original cartridge. can't hurt right? AT440 out, ohhhhhh ummmm forgot to turn off the amp and caused a really (no, seriously) loud and not pleasant sounding thump and BUZZ (bigger than before). I stood slightly comatose for a moment. Ok, retrace my steps and put the cartridge back. What idiot makes the same mistake twice right? Amp was still on. Corresponding thumb and BUZZ. No, sorry, reverse order, BUZZ and then thump this time.

I'm the first to admit my diagnostic skills are in need of improvement.

Now I have a constant buzzing. I'm intensely unhappy at this stage. I turned everything off. Counted to ten and then turned everything back on. Still buzzing. Really not a nice buzz either. Bees buzz very pleasantly, almost dolefully, but this was anything but. I took a deep breath and removed the Earth wire. The buzzing stopped. Everything quiet and very peaceful. Litmus test, record on. Nice sounds, no buzz, no squeak. Or squawk. I'm a genius I proclaimed.

Genius aside. What exactly happened? Why and how is this remotely possible?

I have many more perplexing questions to ask the broader and perhaps smarter Stereonet public, but let's start here.

 

ok right . yes i heard you mate.

when it come to turntable / phono stage , cartridges . hum / buzz . most of them is to do with earthing arrangement . some system don't need earth at all where the other will hum like an airplane without proper earthing .

 

for now you just enjoy your self mate .

 

cheers

Duc

[LogicprObe]

SPEAK UP!

I'M A BIT DEAF TOO!

[Telecine]

Wise advice from Duc. If it is working fine, without any hum, be grateful as these problems can take a bit of solving.

[Toma Audio]

Hmmm methinks you suffered from the dreaded earth loop. It is known to strike all of us that dare to use vinyl at anytime....... sometimes more than once. But Duc nailed it, if you have no hum be at peace.

[davidsss]

Yep, sounds like an earth loop. Using a better phono stage will improve things a fair bit. On the topic of earthing, I just attach the earth and disattach the earth to work out which sounds better and reduces the hum, simple method and it works. I have also swapped around between earthing on an amp and on a step up transformer on a previous system, again, just use which sounds best and has the least hum.

 

Good luck, no doubt you will be sucked into the vortex and be looking to upgrade soon

 

DS

Edited January 7, 2013 by davidsss

[Newman]

Could be one of the cartridges has one of its pins strapped to ground and the other doesn't.

 

In which case one cart needs the external earth wire to earth it and avoid hum, and the other needs it removed to prevent a ground loop.

[Davros59]

Thanks for the feedback.

 

I am Zen like this morning.

 

-_-

[djb]

Great OP more please

Newman your deductive thinking is impressive, I'd never have come up with that.