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PL519 PP design

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#83
Look also for Soviet 6P45S. Those are very similar to PL509.

6p45s_02.jpg
 
#84
Soviet 6P45S is very close to EL509 and also to 6P42S. Svetlana made a version of this tube a couple of years ago, named EL509-03 with an octal socket and no top cap but they had some problems and a lot of tubes were out of spec. I've played with two pairs of EL509-03 and their sound is quite good. In UL- PP with a 3k3 Raa, Up=400V, Ug2=190V and -Ug=50V you can get around 75W loud and clear with THD less than 2%.
Working as a pseudotriode is not a good choice for this valve because of its Ug2 limitations, you better try UL mode with an adequate voltage on its second screen. Another possibility to take advantage of this valve linearity is to drive it on the second screen with an E80CC or even an EL84/83 follower, the results can be surprisingly good.
 
#86
I've used a simple regulator with a big Nmos and zenner diode for reference. So Ug2 was created from Up. Because Ug2 was half of the Up I decided the UL windings must be done interleaved with the primary(ies).
Those UL windings can also be used for KNFB instead of G2 local feedback if the winding wire is changed to support a bigger current.
I will draw the schematic later in the evening and I will post it if it is necessary.
 
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#89
I ran a pair of KT88 in triode mode in my original design of the LUXMAN MB3045 with 60 watts continous output. You do need grid current to achieve that.
The PL509 connected as a triode runing of 250 volt with about neg 50 volt bias will
achieve 30 watts through an output transformer.

I have been comercially using the PL509 for 40 years. I know and have used the russian 6P45 but they did become scarce. They have a high number that are slightly gassy. So I could only use about 50% of those bought.

I remind you of my Enhance Mode Triode amp circuit on this forum called the EAR859.
Published in HiFi News several years ago.
 
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#91
artosalo said:
Thanks. Please post the schematic, if possible.
Click to expand...
Here it is the schematic for one channel and here the Up and Ug2 regulator. Any Nmos which can handle 600V and at least 1A should do the job there.
For the preamp section and driver stage I don't have the numbers right now for each component but it depends on the tubes used there. In that configuration 6N1P, 6N2P, 6N3P, 6N6P or 6N23P will fit if a properly bias is achieved. A plus for this configuration is the DC coupled long-tailed pair. Output transformers are DIY wounded by a friend, having about 17 sqcm in section each grain oriented steel core. Building such an amp I've aimed a very low distorsion gear so at 50W on 8R I've measured a THD=0.35%@1kHz with a -1dB band 20Hz-25kHz and a TID about 0.1-0.2% (according to a 2tone CCIF standard) which was enough to listen to any kind of music and to enjoy every of its details.
 
#92
Thanks for the schematic.
Assuming I read your schematics correctly, it seems to be pentode connected with regulated screen voltage, but not UL.
In case of UL there should be the varying AC-component included. Now it is pure DC.
 
#95
Hi ,

Quote:
Originally Posted by Tony
TV horizontal sweep tubes were used here...... McIntosh MC 3500 MC 3500 Mono Amplifiers Used in Recording Studio | eBay

as pentodes, sure...
If someone wants power instead of the usually quite nice distortion spectrum of a quasitriode it doesn matter how useful they are in triode-connected.
Click to expand...

It´s quite a bit funny. The valves with the worst reputation at all will be used in one of the best sounding amp are ever made .

I made replicas of these beasts. And I´m not gutted with it. 😀


No matter which of these line output valves you are are obtained, they all will not work satisfactionally in a single ended circuit, even in triode mode. In PP -class B , they also tending to "run away" . They need to be burn in for several hours/days . Optimal results can be obtained with an bias servo control circuit.

I matched the valves for my MC-3500 replica 2x8 out of 90 valves purchased from a russia ebay dealer.

here a link to my hombrew amps.

http://www.diyaudio.com/forums/tubes-valves/139241-mcintosh-mc-3500-schematic-information-2.html

the pictures and descripions starting at post #14 transformer winding.

73
Wolfgang
 
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