Hello tubes folk,
I am looking for my first tube work, a cheap but good enough stuff for the circa 70V/circa 12 mA plate of an Philips E188CC. This low microphonic tube will be used for the cool nice Thosten Losch I/V stage, for the TDA1541A.
I want the easiest and cheapest way: no expensive power transformer with center tape. No rectifier tubes, no Tango choke for the plate. Foun a 240/0.1A 6,3V/2A power traffo and also one with 235V/0.05 A but R Core with no screen.
As the tube is a non used pretty cool NOS from 1974, 10 000 h rated, my goal is to include some life span protection, i.e. soft start and CCS. Reg for the filament.
A friend advices me the Moglia gyrator pcb for instance for the plate but it is a litle complicate to import things in continental Europe today and the christmass period is not enhancing that, uh.
I also read about CCS coupled with caps multplier which is a litlle less efficient on the ripple than a gyrator but much better for the noise. It has also a lower output impedance than a gyrator if I understood what I read from Elvee, Prasi, Mark Johnson and numerous skilled members. But my understanding is a tube is sounding better if powered by a higher impedance so the gyrator being more the logical choice ? PSRR only and get rid of the noise floor needed with 16 bits DAC (around 95 to 100 dB ???) ?
Seems also a IHT tube does't need sota low noise for the filament but a soft start for a solid state rectifier circuit is a goodn dea for the tube life spam though. Danger being the filament being hot enough when the plate is powered.,..counterproductive for the tube health. This a 6,3 V/375 mA filament.
Better to use it 6,20 V for example if the life span comes before the sound quality target?
How would you proceed, please ? Two power switch one first for the filament with a soft start to avoid the inrush voltage/curent and a second power switch for the plate ?
What would be your choice for the non choked plate, a CCS gyrator, a reg & cap multiplier with tamed peak voltage at start on? Something else ?
Is anyone aware about gerbers or cheap pcbs for that ?
The game being to stay cheap but good enough. Could you please illustrate Loesch shematic about its power supply please. I will use just one tube only, one half for each Channel, no buffer. So not wo tubes as the pdf. But would like beginn with his cheap power stage. Found already a Hamond 159P for the choke loaded voltage rectification
Many thanks for your help.
I am looking for my first tube work, a cheap but good enough stuff for the circa 70V/circa 12 mA plate of an Philips E188CC. This low microphonic tube will be used for the cool nice Thosten Losch I/V stage, for the TDA1541A.
I want the easiest and cheapest way: no expensive power transformer with center tape. No rectifier tubes, no Tango choke for the plate. Foun a 240/0.1A 6,3V/2A power traffo and also one with 235V/0.05 A but R Core with no screen.
As the tube is a non used pretty cool NOS from 1974, 10 000 h rated, my goal is to include some life span protection, i.e. soft start and CCS. Reg for the filament.
A friend advices me the Moglia gyrator pcb for instance for the plate but it is a litle complicate to import things in continental Europe today and the christmass period is not enhancing that, uh.
I also read about CCS coupled with caps multplier which is a litlle less efficient on the ripple than a gyrator but much better for the noise. It has also a lower output impedance than a gyrator if I understood what I read from Elvee, Prasi, Mark Johnson and numerous skilled members. But my understanding is a tube is sounding better if powered by a higher impedance so the gyrator being more the logical choice ? PSRR only and get rid of the noise floor needed with 16 bits DAC (around 95 to 100 dB ???) ?
Seems also a IHT tube does't need sota low noise for the filament but a soft start for a solid state rectifier circuit is a goodn dea for the tube life spam though. Danger being the filament being hot enough when the plate is powered.,..counterproductive for the tube health. This a 6,3 V/375 mA filament.
Better to use it 6,20 V for example if the life span comes before the sound quality target?
How would you proceed, please ? Two power switch one first for the filament with a soft start to avoid the inrush voltage/curent and a second power switch for the plate ?
What would be your choice for the non choked plate, a CCS gyrator, a reg & cap multiplier with tamed peak voltage at start on? Something else ?
Is anyone aware about gerbers or cheap pcbs for that ?
The game being to stay cheap but good enough. Could you please illustrate Loesch shematic about its power supply please. I will use just one tube only, one half for each Channel, no buffer. So not wo tubes as the pdf. But would like beginn with his cheap power stage. Found already a Hamond 159P for the choke loaded voltage rectification
Many thanks for your help.
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I am trying hard to promote a very simple idea able to solve any class A tube preamp or amp easily.You only need a 12v switching power supply ( i chose a sony play station 2/3 or xbox360 12v ps which are pretty low noise for audio .You can modify them easily to give 12.6 v instead of 12 , but 12v is good enough for fillaments.Then you can to build a 4 transistor baxandall resonant converter for the anodes raising the 12v to whatever voltage you need like i did here for my Luxman cl34 clone following Davekni advice which proved to be really usefull so all credits to Dave for the schematic: Baxandall converter strange output
Attachments
You welcome...for both topics.You may ask a moderator to merge them both together...Luxman cl32-34 schematic showed me the best way to use a cap multiplier for fillament noise reduction, but then i needed a 390vdc for anodes and i didn't have the money to buy an R-Core transformer which still is the best solution for supplying a low noise circuit, so i tried to be a little bit creative with the components i had at hand.
Merging the two threads....hm I don't know as some tubes guys are allergic to sand and solid state rectifiers.
Ah looked on the luxman shematic...classic multiple CRC for small ripple, small noise, delay start on the B+...simple but HT caps are expensive. Anyway I have to simulate it it in PSUD2 to try to understand..
A simple LM317 should be enough for the heater, these little tubes have solid enough filament. Seems the little 2200 uF // caps are slowing things? Does Loesch uses 3 because it is 3 times 90° phase =270° ? Or it is just the smaller values in // give enough noise filtering while limiting inrush peaks with the help of the small 0R68 VS two standalone bigger cap with same resistor in between? My concern about filament slow start is not so about filament life span but sudden heat cause the low resistance of the cold filament from a SS rectification by inrush current that could stress tube materials and create small leaks with the time ? Or one just doesn't care cause a LM317 or LT reg serie slow things enough?
For the B+ I assume the final resistor that load the plate plays also a role in the slow start ? I will swap it for a gyrator or a CCS cap multiplier with mosfet, perhaps.
However I have no idea of the parts values needed for it to acheive around 70 V from the 210VDC? Is it just the cooling of the mosfet or darlingtons that acheive that by heat loss ? Or do I need a serie reg before the CCS of the B+ to drop the 210-70 VDC ?
Ah looked on the luxman shematic...classic multiple CRC for small ripple, small noise, delay start on the B+...simple but HT caps are expensive. Anyway I have to simulate it it in PSUD2 to try to understand..
A simple LM317 should be enough for the heater, these little tubes have solid enough filament. Seems the little 2200 uF // caps are slowing things? Does Loesch uses 3 because it is 3 times 90° phase =270° ? Or it is just the smaller values in // give enough noise filtering while limiting inrush peaks with the help of the small 0R68 VS two standalone bigger cap with same resistor in between? My concern about filament slow start is not so about filament life span but sudden heat cause the low resistance of the cold filament from a SS rectification by inrush current that could stress tube materials and create small leaks with the time ? Or one just doesn't care cause a LM317 or LT reg serie slow things enough?
For the B+ I assume the final resistor that load the plate plays also a role in the slow start ? I will swap it for a gyrator or a CCS cap multiplier with mosfet, perhaps.
However I have no idea of the parts values needed for it to acheive around 70 V from the 210VDC? Is it just the cooling of the mosfet or darlingtons that acheive that by heat loss ? Or do I need a serie reg before the CCS of the B+ to drop the 210-70 VDC ?
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