There is both under the chassis , 100K-33K heater DC lift approx 90v above ground or not if needed .
+- 8 v .
The Connection is on the B+ after the first choke/cap ( for the heater ground ) before splitting into two additional DC chokes one for each EL509 ( channel ) split rail gives better channel separation .
Will see what transpires
+- 8 v .
The Connection is on the B+ after the first choke/cap ( for the heater ground ) before splitting into two additional DC chokes one for each EL509 ( channel ) split rail gives better channel separation .
Will see what transpires
Heaters worked well without lifting them above ground.
Think I will look at 6SL7 DC coupled to a EL84 , cathode drive the EL509 next
Think I will look at 6SL7 DC coupled to a EL84 , cathode drive the EL509 next
OK built the SE EL509 with both PCL82 and ECL82 .
Did not need to lift the heater potential above ground for the PCL82
Bob Danielak design needed work on the input stage so modified the circuit for the input tube .
Bias is set to 1.5v on the triode section of the ECL82 now , still 25mA on the cathode of the Pentode/ triode strapped section .
The top caps on the EL509 contain 100mA -350v DC so some care needs to be taken with these , preferably a tube cover of some description min 45mm internal diameter.
These tubes run stinking hot so the tube cover will need to be isolated from the top plate of the chassis , PTFE washers will suffice on both sides of the chassis.
The Russian Ceramic 9PIN B9D MAGNOAL top mounted helps keep the heat of the chassis.
There is considerable tweaking of resistors needed to bias correctly both stages on the input driver tube to achieve an even balance even with closely matched tubes.
Sound wise into a 5k / 8ohm load the Amplifier is very nice IMHO .
Very fast,dynamic, revealing good frequency extension, lovely midrange.
Better to my ears than a SE300B which i have built quite a few of .
A 2A3 objectively sounds more extended in the bass region but obviously lacks the power of the SE EL509
Did not need to lift the heater potential above ground for the PCL82
Bob Danielak design needed work on the input stage so modified the circuit for the input tube .
Bias is set to 1.5v on the triode section of the ECL82 now , still 25mA on the cathode of the Pentode/ triode strapped section .
The top caps on the EL509 contain 100mA -350v DC so some care needs to be taken with these , preferably a tube cover of some description min 45mm internal diameter.
These tubes run stinking hot so the tube cover will need to be isolated from the top plate of the chassis , PTFE washers will suffice on both sides of the chassis.
The Russian Ceramic 9PIN B9D MAGNOAL top mounted helps keep the heat of the chassis.
There is considerable tweaking of resistors needed to bias correctly both stages on the input driver tube to achieve an even balance even with closely matched tubes.
Sound wise into a 5k / 8ohm load the Amplifier is very nice IMHO .
Very fast,dynamic, revealing good frequency extension, lovely midrange.
Better to my ears than a SE300B which i have built quite a few of .
A 2A3 objectively sounds more extended in the bass region but obviously lacks the power of the SE EL509
As shown in my posting #70 EL509 (JJ) or PL519?, I also had to tweak many components to achieve at least 9 watts of maximum output power. With new tubes, mind you! Bob Danielak's 12 watts are way beyond the capability of his circuitry, I think, unless the Svetlana EL509, which is nothing else than a 6P45S, differs considerably from the European one.
Best regards!
Best regards!
I achieved more than 9 watts , but 11 watts is only a 0.87dB increase and unlikely to add to the listening experience , 1dB seems to be the human threshold for most folk to notice even a slight increase in level. Now 3dB is useful.
Then comes the vexed issue with a single ended tube to achieve 20 watts .
6C33C or GM70 maybe , not a big fan of parallel single ended designs .
The former with low voltage and high current , or the later with high voltage low current.
Time for a new thread i think.
Then comes the vexed issue with a single ended tube to achieve 20 watts .
6C33C or GM70 maybe , not a big fan of parallel single ended designs .
The former with low voltage and high current , or the later with high voltage low current.
Time for a new thread i think.