LE-300BXLS-SE

About the Emission Labs tubes and how to use them.

Re: LE-300BXLS-SE

Postby hlcs25 » Wed Oct 22, 2014 6:44 pm

Hi J.L.,

Thanks for your response.

1) I used star wireing of course. The sassie is connected only to the negative lead of C7 (ASC 40uF/800 VDC) no other places at all. From the lead of this capacitor one grounding wire runs to the central rail of the power suplies. No grounding wire hook is made.
2) RCA connectors are insulated from the sassie.
3) The schielded cables are connedted as your schematics shows it. Schielded cable used at feedback is grounded only one end as well. Feedback is switchable between 0 and 3 dB. No any changes in hum if I switch between them. Can be any difference if the schielded cable of the feedback is grounded from the output side instead of the input side?

If I connected the input to ground, that means the grid is connected to the ground though 4,7K parallel with 10K (together is 3,2K) the hum is nearly eliminated. I am puzzled.
I tried to ground the RCA ground to the grounding rail without any changes.

Have you got any other idea? Thanks in advance.

mfG. Gábor
hlcs25
 
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Re: LE-300BXLS-SE

Postby J. Leven » Thu Oct 23, 2014 5:51 am

Hallo,
zu 3) ich glaube nicht dass der Brumm daher kommt

ich würde folgendes testen :
- verbinde die 6,3V DC Heizung über die 2x 150 R direkt mit masse
- deine delay Schaltung im Eingang der 6SN7 komplett abklemmen, vielleicht ist dort eine Brummschleife eingebaut

Grüße J.L.
J. Leven
 
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Re: LE-300BXLS-SE

Postby hlcs25 » Thu Oct 23, 2014 5:31 pm

Hi J.L.,

Eureka. The delay timer circuit was not grounded! Elementary failure. It is perfect now. Your suggestion helped me a lot. Thanks once more.

mfG, Gabor
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