EL509 (JJ) or PL519?

[Simply Audio]

A couple of other operating points to 4.8K load PL519 El509

 

[Simply Audio]

As ECC83 and ECC82 are easily available the Synola schematic seems the easiest option for the EL509 PL519

 

[timgrindell]

I would suggest building the EAR859 amplifier.
The design is in the public domain and many many have been built.
I built the amplifier and can recommend it
tim

 

[Francois G]

I would suggest building the EAR859 amplifier.

Tim, I spent some time searching for the schematic on the internet. All I could find was a fuzzy “psuedo schematic” without power supply voltages and transformer details. Do you have a clean schematic to post here, please?

 

[timgrindell]

Hi Francois,
It took me only a moment to find the schematic on this forum.

https://www.diyaudio.com/forums/tubes-valves/27132-ear-859-questions-2.html#post316531

https://www.diyaudio.com/forums/tub...transformer-300b-shootout-12.html#post4289564

The B+ is shown (500V) and if you search you'll find where TdeP says the OPT impedance is 4.8K.
There are photos of the commercial amp innards to give you ideas for the layout.
It is a very stable reliable design.
best
tim

 

[Francois G]

Thank you very much!

 

[timgrindell]

Oh yeah, I forgot.
The 519/509 runs at 80mA.
So your load-line was not far off.
(and of course the 4k7 input is wrong--it's 47k as you'd expect)
I'm no expert but feel free to ask any questions.
t

 

[Francois G]

Thanks again. What is R in the schematic in the power supply as well as on top of the driver (cathode follower) tube? If the two R’s are to be connected it would short circuit half of the power siupply.

 

[timgrindell]

R = Right channel
t

 

[Simply Audio]

Hi , I notice the PCL82 heaters are lifted by 100K-33K resistor from ground to protect the heater / cathode potential .
Any issues if both the PCL82 and EL509 both have DC heaters ?
Anyone free to comment

 

[TonyTecson]

id dc coupling, dc lifting the filaments is mandatory..

the input tubes can benefit from dc heating, the power tubes, not so much..

 

[Simply Audio]

Sorry only DC to the PCL82 heaters not EL509

 

[Simply Audio]

To qualify my comments , its people who have built Single Ended EL509 who have tried AC verses DC heaters on the PCL/ECL 82 tube in the Bob Danielak design - SE EL509

 

[Kay Pirinha]

As shown in the schematics previously, my build features plain AC heating for all the valves, without any issues. That's all the tubes involved are designed for. Remember we're talking about line levels at least.
Best regards!

 

[Simply Audio]

thanks Kay, for the feed back , but will DC heaters on the PCl/ECL82 work regardless if the EL509 are AC heaters

 

[Kay Pirinha]

Of course. Why shouldn't it? You need two separate heater windings anyway with your set of tubes.
Best regards!

 

[Simply Audio]

PCL82 Cathode to heater Voltage Max 200v , so if there is less than 200V across the tube no need to lift the heater potential with 100K>33K to ground

 

[TonyTecson]

if that is a concertina phase splitter dc coupled to the pentode plate, then that means the cathode will be at a dc potential of more than 6vdc, perhaps 100vdc or there abouts, i will use a dc lifter anyway...

 

[Simply Audio]

single ended DC coupled PCL82>EL509
350 B+ > 47R> 349V on plate of the PCL82 160v on cathode -10K cathode R > 20mA

 

[TonyTecson]

any way, you do not have to make up your mind now, but make provisions for a ground dc lifter, when the amp is running listen for spluttering noise on your speakers, if you hear none, then congratulations, you do not need to do anything more....

but if you did hear some noise, connect the dc lifter on the first tube and that should clear the noise..

there is an unwritten rule with tube circuits, that is never leave any element floating however if unused.....filaments included...thus we see in many cases, one side of the filaments connected to ground...