Ankunft in Dortmund und Bitte um Isolationstrafo-Hilfe

[Kurorin]

Entschuldigung Freunde noch keine deutsche Sprache.
Ich wohne jetzt in Dortmund; Ich komme aus Chile.
Just arriving two weeks ago.
I´m presenting my LCR RIAA pre-Amplifier, Röhrenverstäarker. The engineer who made this gear for me in Japan told me about this Forum.
I need an Isolation Trafo 230V>230V because I have Ground noise in the electrical net; old building. Measurement shows 1.16V in Ground.
I don´t have my trafos with me because they were to heavy to bring.
Do you know who can made an isolation Trafo for me? Best audio quality and noiseless. 
I´m a valve sound lover.
Danke schön
Victor

   

[hoeberlin]

Hi, Victor,

normally there schould be no Problem with this.

As far as i understand, the whole System consists of Amplifier, Record Player, and Speakers?

Then You schould use one single Wall Outlet, and a multiple 230 Volt Adapter. There schould only be one single point connected to Ground, which normally is the Power Supply Cable of the Amplifier.

As long as the Power Supply Cable of the Record Player goes exactly to the same 230 Volts, and also gets Ground from there, there schould be no Problem.

If the Record Player has a Power Line without Ground, then You may need to run a single wire from Ground / Chassis Amplifier to Chassis of the Record Player.

Please also try to rotate the Plug 180 Degrees, either the Record Player, or the Amplifier, or both.

Please be aware, that if you have a second Point to Ground somewhere else, like Antenna Wall Outlet to a connected Radio Tuner, this indeed might cause a Problem. In that case You need to by a " Mantelstromfilter", that is a short Antenna Cable with Capacitors for inner Wire and shield of the Antenna Cable. That isolates the Antenna Ground from the Tuner.

Hope this helps,
Best Regards,
Henning

[Kurorin]

Ohhh Danke schön Henning.
I´ll follow your recommendations and I´ll report.
This is my system:

-Röhrenvorverstärker RIAA LCR 220V (new and just arrived).
-Röhrenverstärker 100V (valve Radiotron UX245)
-Plattenspieler Victor TT-81 100V (for Japanische market)
-Plattenspieler JVC QL Y3F 220V (for Deutsch market)
-Trafo 220V>100V Sanyo TSD-N11LES, with japanese cable plug; ground is apart, in the chassis.

Ground noise happens with both Plattenspieler at the moment.
With my other vorverstärker RIAA (Sutherland Ph3D working just with batteries, no ground noise at all).

I´ll do like you say, paying attention in every detail. Hopefully works.
Very appreciated your help. I´m ignorant in electrics and electronics just advanced user and lover of SET Röhrenverstärker and Schallplatten.
I think I can´t add another picture here... not sure.

Unluckily the Trafo 220V>100V what I bought here at ebay.de is very noisy, but still no options (I had a good technician in Chile not yet here). I´m looking for a dedicated handmade Trafo 220V>100V. I´m not sure if I can fix mine (really very noisy). Or just maybe change the Power Trafo to the amplifier.

Victor

[Kurorin]

Hi, Victor,

normally there schould be no Problem with this.

.....

No luck 
The connection at the moment is the next:

- Röhrenverstärker 100V plugged to Trafo 220V>100V Sanyo
- Trafo 220V>100V Sanyo connected to outlet wall; it has a japanese cable with plug without ground but ground connection in the chassis, so chassis of Trafo 100V connected to outlet wall ground (first option) and second option connected as well to metal pipes from the wall (heater). Third option is without any ground from the Trafo chassis.

Then...

- Röhrenvorverstärker RIAA is 220V so is connected in different outlet wall plug than Röhrenverstärker. I tried with ground and without ground from the electric net. Anyway Röhrenvorverstärker RIAA has not Ground connected to the Power Supply Cable: its Ground needs to be connected from its chassis. So is connected to the Röhrenverstärker. I tried direct to another Grounds as well like a test. I mean, both chassis are connected.
- Plattenspieler is 220V and no Ground in Power Supply Cable but is joint with interconnection cable RCA, what is the usual. In addition I did a direct connection from its chassis but no good results. Anyway the Plattenspieler is just no possible to use without its Ground because the noise in this case is even dangerous noisy for the speakers. Is connected in the same trip than Röhrenvorverstärker RIAA.

So all the system is working with just one Ground. I checked that all the Power Supply cables are in the right position Line-Neutral.
I don`t have any other gear connected in the same trip. No switching trafos like mobile chargers or similar. I have a filtered trip to isolate them, but anyway at the moment everything is disconnected. My DAC is with batteries and even a small lamp is with batteries as well, paying attention to not to contaminate with any switching trafos around.

This is a very sensitive equipment, autobias, Röhrenvorverstärker RIAA lift a small signal from 2mV to 2V so could elevate as well whatever another noisy electrical signal around. I have very well protected power supply cables in both amplifiers (RIAA and Power).
So my idea is the loop Grounds interconnected due a lot of another electric gears in an old building, is producing noise. With regular modern gears is not possible to hear.

The technician in Chile say that is not allow to connect some sensitive machines to the electric net if the Ground voltage is over 1V and specially for these kind of equipment is very bad. His recommendation was to make an special dedicated electric line to this outlet wall or to use an Isolation Transformer special for my requirements. This is a rented place so I think much better just the Trafo. I was using it before and in my experience Trafos are absolutly helpful and in this case looks is a must. I think.

Whatever advice to make an audio isolation transformer is very appreciated. Or another advice as well  
   
Victor

[Kurorin]

Ground voltage test

   

[hoeberlin]

Hi, Victor,

maybe you have seen the PN, that i have sent to You ( see Private Nachrichten in upper Part of Page ).

What You measure here, is the Voltage between Neutral and Earth, which schould not be the Reason, why you have a Problem.

The Ground in the AC Outlet schould not have a significant Difference to another Ground ( Metal Parts of Heating Pipes etc. .

I had a Tube Amplifier ( The Fisher X101D ) in use some Years ago, also with Record player, and had absolutely no Problem. ( The X101D has an included Mag Preamp ).

BR Henning

[Kurorin]

Hi, Victor,

maybe you have seen the PN, that i have sent to You ( see Private Nachrichten in upper Part of Page ).

What You measure here, is the Voltage between Neutral and Earth, which schould not be the Reason, why you have a Problem.

The Ground in the AC Outlet schould not have a significant Difference to another Ground ( Metal Parts of Heating Pipes etc. .

I had a Tube Amplifier ( The Fisher X101D ) in use some Years ago, also with Record player, and had absolutely no Problem. ( The X101D has an included Mag Preamp ).

BR Henning

Thank you very much Henning. So nice.
Now I saw your message. I´ll do what you recommend.
Best regards!
Victor

[Kurorin]

Danke schön to everybody.
I would like to report the solution to my problem in the classic old style:
- To decouple the audio signal from the chassis; what is necessary to do when the voltage Ground is over 1V (and no working well).
Anyway in my experience isolation Trafo helps to clean the electric signal; old clean classic style to filter, at least for Single Ended with 0 NFB and most modern designs.
Not that much information I think but maybe this link could help: https://nekolab.it/2021/03/23/ground/
Kuro