Here are my new 6922 matched Tubes that I bought from a seller yesterday.
He gave me the opportunity to even to listen to a few, in DIY'ed PP and SE Phono-amps, and some other known good and even more expensive ones for over 100€. He even told about one that supposedly costs 800€, ofcourse we didn't test it
We listened to a few goodies of tubes and cheaper ones too, among those are the listed ones here below.
I still liked them, though he said they can be microphonic. But these here might not be as good as the best, but they are at least built like a tank and built to be portable so to speak. To survive transport from A to B.
I have one crucial question that is imperative to the designing process of my two Gain stages Mic preamp.
It's the TwinLine amp that I am trying to build, perhaps even prototyping first on wood by soldering point to point?
But some design question I have for you to get clarified to me beforehand please.
First let's have a look at my custom PSU transformer in process.

Please don't be dismayed by the exposed laminations of the Tx.
I wanted to show you a fully assembled picture but it's not imperative, it's somewhere on my phone probably.
It's a two legged core, capable of delivering 63W of Power and I am positive you can imagine the cubic vintage looks of it.
My question is this, like the title above:
Some commercial designs that are out there for mic preamps, have a switchable HT Voltage (I guess, I'll have to look up a single specific schematic) where you can switch the tubes running hotter or colder, right, don't get me wrong I am a beginner in tubes, and am currently learning the cathode bias, and the way how you can change the tube character.
Is this done also, in terms of higher HT voltage ( I guess) for hotter or lower HT voltage for perhaps even a starved plate operation, where you can switch from running the tube very hot, shorter life expectancy, to running the tube cooler.
My Question is this:
I have to know whether this is reasonable/feasable and done in this manner - just sanity checking here for the most part - to incorporate one more secondary, e.g. one that is for running both stages/or just one stage hot with an output Voltage let's say of 245V? (I dont know yet, or 185V?)
I faintly remember the limiting Anode voltage is around 300V for either the 5751 or the E88CC/6P23N, and I'll get to my available tubes now, I have a 12ax7 (chinese) a 5751 (TAD) as Mic stage and two matched 6P23N (russian) as line out stage.
I want to know this, do I have to accomodate a 4th secondary on the PSU, to achieve this above?
We have two options here, We can put out with 3 secondaries P1 280V, P2 48V for Phantom 100% certainly needed, 6,3V for heater 100% needed, and depending on your ansers tapping for a lower voltage., say 90V for starved plate design in parallel for example.
I apologize to you for my brief english and grammar mistakes, by chatting with you I improve myself in your language.
Because I want it to be in terms of driving the tube hotter or colder, switchable/selectable, for both gainstages, I don't necessarily want to change the headroom by changing the cathode bias, is that possible?
Or am I oversimplifying and misunderstanding the concept behind the switch that on some designs the lets the tubes run hotter or colder.
Do I need the HT Voltage and the lower HT voltage to come from tappings on the transformer or by a Voltage divider getting supplied by just one primary source?
If you can recommend to me Voltages at which those two stages can run at simultaneously that sound best that would be mega cool!
Because my schematic for the TwinLine amp IIRC doesn't mention the HT voltage, the tubes should be running at for recording vocals, because I have no clue, It's not ment as a distortion box.
I can probably look up on the internet what they recommend for the 12ax7, or 5751v as input stage and the E88CC in a system, and see where they overlap in their voltage ranges and that's the range how low and how high one can go with the HT rail.
I looks like nothing now, but it's just early, missing a lot of electronic parts that are about to get ordered, I don't want to make many small orders and pay 60€ just in delivery costs, makes not much sense to me.
It's a side project that is worthwhile, hopefully
Hopefully you understood what I want to achieve out of this project, and thank you for your replies.
Please tell me if you don't like this idea.
Thank you for your reply!
He gave me the opportunity to even to listen to a few, in DIY'ed PP and SE Phono-amps, and some other known good and even more expensive ones for over 100€. He even told about one that supposedly costs 800€, ofcourse we didn't test it

We listened to a few goodies of tubes and cheaper ones too, among those are the listed ones here below.
I still liked them, though he said they can be microphonic. But these here might not be as good as the best, but they are at least built like a tank and built to be portable so to speak. To survive transport from A to B.
I have one crucial question that is imperative to the designing process of my two Gain stages Mic preamp.
It's the TwinLine amp that I am trying to build, perhaps even prototyping first on wood by soldering point to point?
But some design question I have for you to get clarified to me beforehand please.


Please don't be dismayed by the exposed laminations of the Tx.
I wanted to show you a fully assembled picture but it's not imperative, it's somewhere on my phone probably.
It's a two legged core, capable of delivering 63W of Power and I am positive you can imagine the cubic vintage looks of it.
My question is this, like the title above:
Some commercial designs that are out there for mic preamps, have a switchable HT Voltage (I guess, I'll have to look up a single specific schematic) where you can switch the tubes running hotter or colder, right, don't get me wrong I am a beginner in tubes, and am currently learning the cathode bias, and the way how you can change the tube character.
Is this done also, in terms of higher HT voltage ( I guess) for hotter or lower HT voltage for perhaps even a starved plate operation, where you can switch from running the tube very hot, shorter life expectancy, to running the tube cooler.
My Question is this:
I have to know whether this is reasonable/feasable and done in this manner - just sanity checking here for the most part - to incorporate one more secondary, e.g. one that is for running both stages/or just one stage hot with an output Voltage let's say of 245V? (I dont know yet, or 185V?)
I faintly remember the limiting Anode voltage is around 300V for either the 5751 or the E88CC/6P23N, and I'll get to my available tubes now, I have a 12ax7 (chinese) a 5751 (TAD) as Mic stage and two matched 6P23N (russian) as line out stage.
I want to know this, do I have to accomodate a 4th secondary on the PSU, to achieve this above?
We have two options here, We can put out with 3 secondaries P1 280V, P2 48V for Phantom 100% certainly needed, 6,3V for heater 100% needed, and depending on your ansers tapping for a lower voltage., say 90V for starved plate design in parallel for example.
I apologize to you for my brief english and grammar mistakes, by chatting with you I improve myself in your language.
Because I want it to be in terms of driving the tube hotter or colder, switchable/selectable, for both gainstages, I don't necessarily want to change the headroom by changing the cathode bias, is that possible?
Or am I oversimplifying and misunderstanding the concept behind the switch that on some designs the lets the tubes run hotter or colder.
Do I need the HT Voltage and the lower HT voltage to come from tappings on the transformer or by a Voltage divider getting supplied by just one primary source?
If you can recommend to me Voltages at which those two stages can run at simultaneously that sound best that would be mega cool!
Because my schematic for the TwinLine amp IIRC doesn't mention the HT voltage, the tubes should be running at for recording vocals, because I have no clue, It's not ment as a distortion box.
I can probably look up on the internet what they recommend for the 12ax7, or 5751v as input stage and the E88CC in a system, and see where they overlap in their voltage ranges and that's the range how low and how high one can go with the HT rail.
I looks like nothing now, but it's just early, missing a lot of electronic parts that are about to get ordered, I don't want to make many small orders and pay 60€ just in delivery costs, makes not much sense to me.
It's a side project that is worthwhile, hopefully

Hopefully you understood what I want to achieve out of this project, and thank you for your replies.
Please tell me if you don't like this idea.
Thank you for your reply!
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