I have a bunch of 6S19 and I have pondered series wiring for a OTL.
To be honest I like this idea best.
One could devise a suitable series parallel grouping, to minimise the risk to many tubes, and yet still drop the requirement for current.
I've gone through this thought process recently for that old Broskie 10 tube EL84 amp. Once you get the current and voltage to reasonable levels then you have many options without resorting to giant heat sinks, giant transformers etc.
So for 4A @ 31.5 volts any of the following could be built without unusual parts:
- A Meanwell SMPS (maybe 8-12 A to keep it from shutting down)
- Plain old AC (trimmed with a resistor)
- Plain old DC supply (trimmed with a resistor)
- A 5A "LMxxx" current regulator set to 4A (maybe with 2 paralleled LM devices to double the current)
- A 5A "LMxxx" voltage regulator set to 31 V (maybe with 2 paralleled LM devices to double the current)
- A capacitor multiplier linear supply (trimmed with a resistor)
I read somewhere that series heater strings prefer current regulation. I'm still deciding best way to heat 10 EL84's for the Broskie amp in one of his very early articles:
It would be nice to have a look at this amp and the schematic,
but sorry the Koonw account is "disabled" - whatever it means .
You can run 6.3V heaters in series, no problems, other than the need of matching the tubes pretty well heater-wise. I've done that. Same with P-tubes in parallel.
@as_audio, account disabled is self explanatory, you will not be able to contact him through the forum, you can try to search the forum for more info on his amp in question.
While not what the thread reviver asked, I actually don't like many of the answers to this thread, series string rated tubes were developed especially for mixing tube types in a single string. Using identical tubes in a string even if not series string rated should not be a problem.
Wow, just realized jean-paul's account was disabled, quite shocking for a former moderator! 😱
While not what the thread reviver asked, I actually don't like many of the answers to this thread, series string rated tubes were developed especially for mixing tube types in a single string. Using identical tubes in a string even if not series string rated should not be a problem.
Wow, just realized jean-paul's account was disabled, quite shocking for a former moderator! 😱
Off topic, for me it is hard to understand the precise meaning of
banned, account disabled, on hiatus and other terms like this, only
r.i.p. is easy.
banned, account disabled, on hiatus and other terms like this, only
r.i.p. is easy.
Today I even see a new phenomenon : "Deleted member xx" and you can not even find his old forum content. Where can I read about the rules ?
The forum rules are accessed by the pulldown on the top left for me as I view it on a mobile device using Chrome. Can't see a way to link to it.
Mods don't like discussing moderation but you can believe there is even more misbehaviour than is visible to us members as they have extra access and tools at their disposal.
Mods don't like discussing moderation but you can believe there is even more misbehaviour than is visible to us members as they have extra access and tools at their disposal.
series filament strings happened a lot on tube radios and tv sets, no mystery here. millions of these units were made and sold....just do it right and you are fine...