Technics SL1500C hum through external phono??

[Entrigo]

one ground/earth = no hum
two ground/earth - hums with multiple earth loops


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Ground Loop Hum

A ground loop hum occurs when there’s a difference in electrical potential (voltage) between different components in your audio setup. This difference can create a loop, leading to unwanted electrical interference manifesting as a low-frequency hum or buzz. Turntables, like many audio devices, are susceptible to ground loop hum.

Multiple Ground Paths: If your turntable and other audio components are plugged into separate power outlets or grounded differently, ground loop hum can occur

OK but how do you get out of it?

And could it be the preamp causing the issue? The turntable plugged into line in using its preamp is silent. Plugged into the Rega amp phono using line out is silent. But plugged into the Moon preamp with TT line out and into the Rega line in - hum...

 

[daytona600]

OK but how do you get out of it?

Take the technics back your dealer for advice or can you try another another phono stage or Turntable

 

[Entrigo]

OK but how do you get out of it?

Take the technics back your dealer for advice or can you try another another phono stage or Turntable

No need. Got a Rega Elex-R yesterday and as said above, the Technics through the Rega phono in is silent ... Save of course the obvious hiss.

So it wasn't the Technics after all. Returned the Moon today and right now really enjoying some low level Beethoven, after having played the White Album earlier on today at significantly higher volume (before playing some CDs and streaming - just to check the amp works as expected).

Now can't wait for tomorrow morning to blast some proper punky / rocky stuff.

 

[daytona600]

Glad you sorted out the hum

 

[Entrigo]

Glad you sorted out the hum

Thank you. I did for a few minutes consider digging a little deeper into the issue thanks to the very helpful diagram you shared. Out of principle, as I really wanted to get to the bottom of it.

But I honestly spent so many hours in the last couple of weeks on this that I just couldn't... So I packed up the Moon and posted it without looking back!

 

[Al ears]

OK but how do you get out of it?

And could it be the preamp causing the issue? The turntable plugged into line in using its preamp is silent. Plugged into the Rega amp phono using line out is silent. But plugged into the Moon preamp with TT line out and into the Rega line in - hum...

If you plug into a phono preamp then you should not be using line out on the turntable.
Is this actually what you are doing?
I am confused by this explanation of yours.

 

[Entrigo]

If you plug into a phono preamp then you should not be using line out on the turntable.
Is this actually what you are doing?
I am confused by this explanation of yours.

Sorry no, I got myself confused with all the various permutations.

It was of course TT line out to amp line in using the TT preamp and TT phono out to phono in of either preamp or amp to use an external phono...

 

[Entrigo]

Now I was reading that the Elex-R has 220pF capacitance and this is to keep hum at bay.

On the Moon I was using either 0 or 100pF to tty and remain within the 100-200pF recommended for the AT carts.

Could that have been the issue?

 

[Entrigo]

Now I was reading that the Elex-R has 220pF capacitance and this is to keep hum at bay.

On the Moon I was using either 0 or 100pF to tty and remain within the 100-200pF recommended for the AT carts.

Could that have been the issue?

P.s. I am probably at over 300 now but can't really hear this much increase in brightness.

So if it is about lower capacitance causing the hum, I would need to be very careful about buying an external phono and just be happy with my set-up...

 

[nopiano]

Now I was reading that the Elex-R has 220pF capacitance and this is to keep hum at bay.

On the Moon I was using either 0 or 100pF to tty and remain within the 100-200pF recommended for the AT carts.

Could that have been the issue?

I have never heard of capacitance in this context affecting hum. All it does is change the HF response of the cartridge.

See the graph in the second post here…

Quick Question About Preamp Capacitance

My preamp's capacitance can be set at 100pf or 200pf. I'm not sure how that relates to my phono cartridge or system? Any info would be appreciated.

forums.stevehoffman.tv

 

[Al ears]

I have never heard of capacitance in this context affecting hum. All it does is change the HF response of the cartridge.

See the graph in the second post here…

Quick Question About Preamp Capacitance

My preamp's capacitance can be set at 100pf or 200pf. I'm not sure how that relates to my phono cartridge or system? Any info would be appreciated.

forums.stevehoffman.tv

Quite so.

 

[daytona600]

Capacitance in phono stage + phono cables add together for total in Pf 100-400
Adjust loading on your phono stage to suit MM cartridge

Incorrect loading too much or too little can make HF sound brittle to Soft
MI moving iron cartridges - Grado , Soundsmith , Nagaoka are not affected at all by Capacitance

 

[Rui]

In this situation that i refer the turntable from Po-Ject that the non existance of a ground wire created a hum, of corse , like many other times in the past non wired ground turntables always had problems and that might be related with the standart electrical system provided in each country, i think, as after a ground wire installed none as this last Pro-Ject turntable had the hum efect of double ground wired , but the next model of the same design came with it, but all is good now, i also two years ago in December aquired a Rega turntable and i´m happy with it no noise under, maybe the quality of the building is related with that, also thankfull for all knowledge i wasn´t aware of before reading here in the coment section all information given`, thank to everyone that contributed with aditional information here in the forum.

 

[Entrigo]

Well. Hopefully final update.. Just got a Pro-ject S3B and it also sounds silent, just like the phono stage of my Elex-R.

So it looks like it was really a freaky coincidence of two faulty ex-demo units (the Rega Fono and the Simaudio Moon).

 

[Fandango Andy]

Hello wise forum-dwellers!

Going mad and would really really appreciate some expert tech advice!

Posted a week or so ago about this issue, thinking the problem was either with my amp or the phono stage but now I think it might be the turntable.

The lowdown:
Over the last couple of months, I ran my Technic TT through different phono options. All of this bar using the Technics own preamp produce a hum. This at full volume is roughly 40dB. As in, measuring around 75dB in total, with a background noise level of 35dB - measured in front of the speakers with a meter app on my phone (it's not scientific, I am a heathen etc so please bear with me).

Combinations tried follows:

• TT through Rega Fono MM into line in of my Marantz PM7200 amp - hum
• TT through Simaudio Moon 110LP into line in of Marantz - hum
• TT through Marantz phono in - hum (though quieter - but then the Marantz sounds MUCH quieter than any of the two external phono - whatever the reason, at the same volume knob position/distance/record playing, it reads nearly 30dB quieter than the Moon)
• TT through Moon into line in of a brand new Fosi mini amp - hum
• TT using own preamp into line in of Marantz - SILENT!

I also tried:
switching off all electrics, double grounding (extra metal wire from ground of Moon to ground pin of next electrical socket), moving away from amp, sitting on foam isolation pads, plugging Moon into extension from next door's socket, swapping RCAs around. Nothing. Also no hum from any of the other channels of the amp.

So:

1. Could it be the turntable phono out signal path or connections that is the problem?
2. Or some other issue in the connection between the TT and the external phonos?
3. Has anyone with a Technics SL1500C which has a similar issue?

I appreciate a proper answer is hard just on paper, but would really appreciate some insights before I take my 'baby' to my local shop - as they have a 4 weeks lead time - and I would rather avoid being without for 4 weeks and them saying "nothing wrong with this"...

Thanks!

Other than the "double grounding" you don't mention grounding. If you haven't already try this:

Unplug everything in the room. To ensure no interference. Plug the amp, preamp and turntable into the same extention lead. Ground the TT to the main amp.

If it works turn everything else in the room on one by one to see if the hum comes back.

 

[Entrigo]

Other than the "double grounding" you don't mention grounding. If you haven't already try this:

Unplug everything in the room. To ensure no interference. Plug the amp, preamp and turntable into the same extention lead. Ground the TT to the main amp.

If it works turn everything else in the room on one by one to see if the hum comes back.

My bad - I thought by saying "double grounding" would clearly imply I had single grounded it first. Obviously not, as keep getting asked if I have grounded it haha. Anyway did try that as well. Unplugged TV extension (TV PlayStation dvd player etc) and also the WiFi. No change.

Anyway, as per latest update,it is now solved. No hum through the Rega Elex phono stage and no hum through a Pro-ject phono stage either. So it looks like it was both ex demo units I tried that were faulty...

I shall now consider buying another Simaudio Moon 110LP, as liked it quite a bit (and as the Pro-ject S3B doesn't seem to add much than the Elex can't do). Even though I can set the capacitance to match closely the requirements of my cart, it's hard to tell them apart. The Moon was a night and day with my previous amp - curious to see if it gives the same improvement on the Elex.

 

[Rui]

I would disagree.
Manufacturers are not going to knowingly market a turntable that isn't correctly earthed.
I will admit some do earth them in some odd manner but they will be earthed.

ok , but the problem persists, since they released the first non earth cable turntable, this counting only from the 90´s or would be a endless number of turntables, if it was working perfect why destroy it

 

[Al ears]

ok , but the problem persists, since they released the first non earth cable turntable, this counting only from the 90´s or would be a endless number of turntables, if it was working perfect why destroy it

Sorry, that does not make sense.
Which turntable was not earthed and if what was working perfectly?

 

[Rui]

No need. Got a Rega Elex-R yesterday and as said above, the Technics through the Rega phono in is silent ... Save of course the obvious hiss.

So it wasn't the Technics after all. Returned the Moon today and right now really enjoying some low level Beethoven, after having played the White Album earlier on today at significantly higher volume (before playing some CDs and streaming - just to check the amp works as expected).

Now can't wait for tomorrow morning to blast some proper punky / rocky stuff.

i normally when the turntable doesn´t sound several times better than the cd player is because it is not a aceptable turntable as it happens with all technics and pioneer turntables i have since young also have some from other brands but technics kept using them as they sound good,

and having bought two turntables in the 80´s and one in the 90´s ,all were very good sounding but in need of repair, i just get one from the 70´s and always working perfect, also the cartridges are the ones that were bought with the turntables, being already very hard to find stylus for some even standart cartridges from technics(made by Nagaoka),

some years ago tried some new Nagaoka cartridges but the one that was almost as good as the one that came with the turntables was the MP-500 or similar reference, maybe NP not MP or the reverse, but the price is a no go and a very limited hours of use in all new stylus.

well i already have some new but avoid using them by two reasons , very limited hours of use and the price of a new one and some not even s good as the 70´s ones, the 2mBlack some years ago very well talked about i have it still closed in the box as it doesn´t seem that good but average like others i own,

the one that surprised me was the less expensive and bought it as when reading the specifications i thought that it had to be good, so i bought it from germany, where i buy all much cheaper the Grado prestige III Gold, and today even at a lower price,

but the one i liked this in a friends store was a grado made of some strange wood but after i hearing it and really liked it i was told the price and didn´t bought it ,it was around 5.000€, my intention is to buy new cartridge to my most used turntables but this new turntables and cartridges aren´t like they used to be,

they play records but with a very low quality ,unless one wants top spend from 50.000€ to 500.000€ in a new turn table with a good new cartridge that i already committed that crime, i have to post some photos of my two, now in use , systems at home, a 70´s one and in other room a more recent system.

Also two turntables from Gold Note with this brand cartridges they sound really good, one is the Pianosa other is the Bellagio, and have a nice design

 

[Rui]

Sorry, that does not make sense.
Which turntable was not earthed and if what was working perfectly?

well they were so many that i never thought of them again but were from known brands and all had issues because of the non earthed characteristic, "makes no sense" , what makes no sense is selling a 1.000€ Pro-Ject turntable and with a constant noise under this to do not refer them low quality of sound that was amazing low to what i was used to, and i have many turntables mostly from the 70´s those never fail or have any issue if correctelly mantained, but talking about the pro-ject from the moment we earthed it with a cable it stayed only a very bad sound quality turntable for a price that was ridiculous high and if disassembled was mostly bits of plastic (MDF they say), don´t know if you are from a time when turntables weren´t like this ....things sold today as the cartridges are good but only from several thousands of € up, the last i realy enjoyed was a gold note there was a blue and a red ,the blue was better not that the other didn´t sounded good and not that expensive but some have not a budget that allows them to buy this now good cartridges but with a very low hours of use stylus , another problem created to steal from people, as it happened a lot throught the last 25 something years

 

[Al ears]

well they were so many that i never thought of them again but were from known brands and all had issues because of the non earthed characteristic, "makes no sense" , what makes no sense is selling a 1.000€ Pro-Ject turntable and with a constant noise under this to do not refer them low quality of sound that was amazing low to what i was used to, and i have many turntables mostly from the 70´s those never fail or have any issue if correctelly mantained, but talking about the pro-ject from the moment we earthed it with a cable it stayed only a very bad sound quality turntable for a price that was ridiculous high and if disassembled was mostly bits of plastic (MDF they say), don´t know if you are from a time when turntables weren´t like this ....things sold today as the cartridges are good but only from several thousands of € up, the last i realy enjoyed was a gold note there was a blue and a red ,the blue was better not that the other didn´t sounded good and not that expensive but some have not a budget that allows them to buy this now good cartridges but with a very low hours of use stylus , another problem created to steal from people, as it happened a lot throught the last 40 something years

Perhaps I shouldn't have asked. Not one maker specified in that post just the normal rant as far as I can see.
You are, of course, entitled to your opinion.

 

[Rui]

Perhaps I shouldn't have asked. Not one maker specified in that post just the normal rant as far as I can see.
You are, of course, entitled to your opinion.

i´ll list you some but i´m in the countryside right now when at home i´ll check what turntables i did the earth/ ground myself as they weren´t sounding good with a loud annoying sound when playing a record, but could start with pro-ject turntables around 1.000€ non earthed, really bad turntables and some on youtube talk like it were perfect, only one conclusion they think we heard records in the 50´s with bad record players, as some Rega too, allthough i have one but not like this price range i refer to earlier, at start i thought that Pro-Ject was a brand for young teenagers as it had photos of artists or bands like one is going to hear only music from George Harrison only, that i respect a lot as he wrotte many good songs but his solo career wasn´t that good but like other Beatles a song here and there that desearves listening, only in Beatles i have to say that his songs are amongst the best of the beatles career more to the end.
Maybe you´re right Pro-ject isn´t a maker of turntables but things that can play records very bad

 

[Al ears]

i´ll list you some but i´m in the countryside right now when at home i´ll check what turntables i did the earth/ ground myself as they weren´t sounding good with a loud annoying sound when playing a record, but could start with pro-ject turntables around 1.000€ non earthed, really bad turntables and some on youtube talk like it were perfect, only one conclusion they think we heard records in the 50´s with bad record players, as some Rega too, allthough i have one but not like this price range i refer to earlier, at start i thought that Pro-Ject was a brand for young teenagers as it had photos of artists or bands like one is going to hear only music from George Harrison only, that i respect a lot as he wrotte many good songs but his solo career wasn´t that good but like other Beatles a song here and there that desearves listening, only in Beatles i have to say that his songs are amongst the best of the beatles career more to the end

Decks are normally earthed in one way or another they don't use separate earth wire as such, Rega for one but I have never in all my years come across a deck that didn't earth in some way.