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Old 25th May 2012, 09:53 PM   #781
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They seem to have very high plate current ratings- 1.4 Amps!
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Old 25th May 2012, 10:29 PM   #782
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While the PL519 have 1500mA cathode peak current ( according to Philips data ) .
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Old 25th May 2012, 11:58 PM   #783
banat is offline banat  Serbia
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Hi
My experience with PL519 tube is that specified Philips data is valid but for only very short time of peak cathode current , of few milisecond duration , in real life tube PL519 will blown internal cathode to tube pin link easy and fast , that is actually the weak point of this tube , similar case is with tubes PL509 , EL519 and El509 , regardless to tube manufacture brand .
PL504 tube don`t suffer from this internal over current peak contact link failure , it is pretty rugged tube .
Best Regards for all !
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Old 26th May 2012, 08:44 AM   #784
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Quote:
Originally Posted by atmasphere View Post
They seem to have very high plate current ratings- 1.4 Amps!
According to the Sylvania datasheet this also means peak current!

Best regards!
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Old 26th May 2012, 10:35 AM   #785
M Gregg is offline M Gregg  United Kingdom
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Quote:
Originally Posted by banat View Post
Hi
My experience with PL519 tube is that specified Philips data is valid but for only very short time of peak cathode current , of few milisecond duration , in real life tube PL519 will blown internal cathode to tube pin link easy and fast , that is actually the weak point of this tube , similar case is with tubes PL509 , EL519 and El509 , regardless to tube manufacture brand .
PL504 tube don`t suffer from this internal over current peak contact link failure , it is pretty rugged tube .
Best Regards for all !
Do you know to any good PL504 OTL schematics?

Regards
M. Gregg
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Old 26th May 2012, 03:17 PM   #786
banat is offline banat  Serbia
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Hi Mr.Gregg !

The best PL504 OTL Amp solution for everyday 24/7 use will be small amp with triode connected 4xPL504 per channel driving 4 x 8 ohm speaker = 32 ohm , or even little higher impedance , based on Atmasphere M60 topolology only !
For higher output power and lower speaker impedance just insert more PL504 tube in parallel .
Special want to point Atmasphere driver DC coupled circuit which is the best solution for full control over PL504 power tubes , but for best possible Amp sonic to .
Atmasphere input voltage gain stage is OK to , but there is only small place for modification and tweaking to .
Best Regards !

Last edited by banat; 26th May 2012 at 03:20 PM.
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Old 27th May 2012, 02:07 PM   #787
M Gregg is offline M Gregg  United Kingdom
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Thank's for the reply,

Where can I get a look at the M60 circuit?
What is the optimum number of pl504's for 16 Ohms or is 8ohm not viable?
I guess the DC coupling stops capacitor blocking?

Regards
M. Gregg
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Old 27th May 2012, 02:49 PM   #788
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Hi banat , or PL36 triode connected too

Last edited by Dimitris AR; 27th May 2012 at 02:54 PM.
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Old 27th May 2012, 04:30 PM   #789
banat is offline banat  Serbia
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Quote:
Originally Posted by M Gregg View Post
Thank's for the reply,

Where can I get a look at the M60 circuit?
What is the optimum number of pl504's for 16 Ohms or is 8ohm not viable?
I guess the DC coupling stops capacitor blocking?

Regards
M. Gregg
M.Gregg

Complete Atma-Sphere M60 DIY article with full DIY support from Mr.Ralph Karsten ( Atmasphere ) you can found here :What tubes for a tube amp?
For 16 ohm speaker you need about 6 or 8 PL504 tubes .
Yes DC coupling driver avoid effect of blocking distortion , but permit A/A2 class of operation for output power tubes with superb sound performance.
BTW , universal good solution for optimum match to relative low output power OTL Amp is to connect 4 or more standard 8 ohm speaker in series , since today is possible to by very good quality speaker unit for relative low money , before 30 or 40 year ago that was not possible .
Best Regards !
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Old 27th May 2012, 04:40 PM   #790
banat is offline banat  Serbia
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Originally Posted by Dimitris AR View Post
Hi banat , or PL36 triode connected too
Yes !

BTW , I prove the excellent quality of PL36 tube on output RF power stage for AM Pirate transmitter , the PL36 stand 1KV B+ with no problem for years , PL504 up to 1,3KV , and PL519 up to 1,5 KV , but PL519 very often flash & burn the cathode to tube pin link , PL 36 & PL504 never .

Best Regards !

Last edited by banat; 27th May 2012 at 04:43 PM.
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