[Roger A. Modjeski]

This is the first in a series of videos that intend to cover the entirety of tube preamp design. Starting with a single stage we will build on basic concepts to multistage amplifiers and their power supplies. Here is the link to the video: http://youtu.be/mrMGGHp8yLk and please follow our channel. We will post on AudioCircle when we put up new videos.

[Ericus Rex]

 

[Ericus Rex]

Can we discuss the video (and preamp design) here in this thread?  You said something in it that has blown my mind and I'd like some clarification.  You said the current flows through the tube from plate to cathode (when you were discussing cathode bias and Rk).  How is this possible if the electrons only flow in one direction (cathode to plate)?!?!

[tubegroove]

Very good learning especially for newbies to tubes like myself. 

Thanks for sharing and look forward to subsequent videos

[Roger A. Modjeski]

Can we discuss the video (and preamp design) here in this thread?  You said something in it that has blown my mind and I'd like some clarification.  You said the current flows through the tube from plate to cathode (when you were discussing cathode bias and Rk).  How is this possible if the electrons only flow in one direction (cathode to plate)?!?!

Rex,

Its just a convention to talk about current flowing from positive to negative. Certainly the electrons go the other way but the convention was well established well before tubes were invented. As some may recall, the British made cars with positive ground for many years, but not anymore. Perhaps they were more concerned about the electrons but they lost out.

Whenever an electron leaves a site it leaves a hole. Positive currents are the flow of holes. We can't see the electrons or the holes, only the effect of them.

[gbeard]

Roger,

This is really a terrific idea. Especially for folks (like me) who have built or rebuilt a little bit of gear and can follow a schematic, but don't always understand the what/why of the circuit design. (Until it is necessary that is  )

Thanks!
gary

[Rclark]

Very good learning especially for newbies to tubes like myself. 

Thanks for sharing and look forward to subsequent videos

+1

[cheap-Jack]

Hi.

This is the first in a series of videos that intend to cover the entirety of tube preamp design. Starting with a single stage we will build on basic concepts to multistage amplifiers and their power supplies.

Single stage line preamp as in the video is not a big deal. Any high school kids can build one after school.

Ever consider the challenge of building a one-single stage RIAA phonostage (or phono preamp)??
Many many say no way - technically impossible.

YET, I've built one & have been using it for a few years now as I am a LP vinyl advocate! Being Open, airy & musical sounding that blows any mult-staged phono-preamps out of the way, IME.

c-J

[Ericus Rex]

Hi.

Single stage line preamp as in the video is not a big deal. Any high school kids can build one after school.

Ever consider the challenge of building a one-single stage RIAA phonostage (or phono preamp)??
Many many say no way - technically impossible.

YET, I've built one & have been using it for a few years now as I am a LP vinyl advocate! Being Open, airy & musical sounding that blows any mult-staged phono-preamps out of the way, IME.

c-J

    Why don't you start a company and market your superior product since you're an expert in the field.


Keep 'em coming, Roger!

[cheap-Jack]

Hi.

   Why don't you start a company and market your superior product since you're an expert in the fiel

Keep 'em coming, Roger!

Why should I???  I am making good money in the electrical engineering industries I have engaged for decades.

IMO, audio to me is a leisure to sooth my business stress. It is NOT a business to make decent money easily.

That said, I still make some casual bucks acting as a free-lance sound consultant.
I build & sell to order, 4N pure silver interconnects & power cords for a premium price.

c-J

[pehare]

there one in every crowd isn't there:)  anyway thanks Roger for taking the time to do this & starting at a basic level for folks like myself.  Can't say I'll ever build my own gear but I already learned a few things.  cheers!  patrick

[richidoo]

That is fantastic. I love how you make it seem so simple.

[Ericus Rex]

Can these same design parameters be used in designing the input stage of a power amp?  If not, what would change?

[Roger A. Modjeski]

Can these same design parameters be used in designing the input stage of a power amp?  If not, what would change?

Yes, this would be a fine input stage for a power amp. It is also typical of a single stage line preamp. Just put a volume control at the input and you have a line preamp.

As to phono preamps mentioned earlier, most phono preamps have two stages to get the required gain and low output impedance. The EQ can be either passive between the stages or active in the feedback loop. I have certainly considered a single stage phono preamp. It's no big deal to do with a high gain pentode however it will have certain limitations such as output drive capability (loading) and noise issues. Anyone who has done one is welcome to share it here.

[cheap-Jack]

HI.

 I have certainly considered a single stage phono preamp. It's no big deal to do with a high gain pentode however it will have certain limitations such as output drive capability (loading) and noise issues. Anyone who has done one is welcome to share it here.

No, even using one pentode may or may NOT obtain enough gain to any power amp without any active linestage.

But I only use 1/2 twin triode to drive direct my tube power amp. Of course, the O/P voltage is way way less than 2V to drive any tube power amp to full rated power.

BUT, but do we really NEED to drive our power amp to FULL power at all time???? I don't think so.

So my 1 tube 1 stage RIAA stereo phonostage is now driving direct my brandname tube power amp via my
DIY passive linestage with volume pot setting from 2 O'clock for high level rock/pop music to sometimes max volume setting for low level classical LP recordings.

The music sounds so open, so elegant & transparent. Also very quiet background at full volume pot setting & TT spinning. Of coure, one should never expect chest punching heavy sound levels due to its low O/P voltage. But the quality of music is totally something else, not those mult-staged phono-preamp can touch...... until one listen to it.

We want quality music, NOT quantity music like a juke box, right?

Guss what triode I used????? NO pentode, please, which sounds "aweful" vs triode.

c-J

[Roger A. Modjeski]

HI.
No, even using one pentode may or may NOT obtain enough gain to any power amp without any active linestage.

But I only use 1/2 twin triode to drive direct my tube power amp. Of course, the O/P voltage is way way less than 2V to drive any tube power amp to full rated power.

BUT, but do we really NEED to drive our power amp to FULL power at all time???? I don't think so.

So my 1 tube 1 stage RIAA stereo phonostage is now driving direct my brandname tube power amp via my
DIY passive linestage with volume pot setting from 2 O'clock for high level rock/pop music to sometimes max volume setting for low level classical LP recordings.

The music sounds so open, so elegant & transparent. Also very quiet background at full volume pot setting & TT spinning. Of coure, one should never expect chest punching heavy sound levels due to its low O/P voltage. But the quality of music is totally something else, not those mult-staged phono-preamp can touch...... until one listen to it.

We want quality music, NOT quantity music like a juke box, right?

Guss what triode I used????? NO pentode, please, which sounds "aweful" vs triode.

c-J

Well, show how it's done Jack.

[guest78998]

HI.
No, even using one pentode may or may NOT obtain enough gain to any power amp without any active linestage.

But I only use 1/2 twin triode to drive direct my tube power amp. Of course, the O/P voltage is way way less than 2V to drive any tube power amp to full rated power.

BUT, but do we really NEED to drive our power amp to FULL power at all time???? I don't think so.

So my 1 tube 1 stage RIAA stereo phonostage is now driving direct my brandname tube power amp via my
DIY passive linestage with volume pot setting from 2 O'clock for high level rock/pop music to sometimes max volume setting for low level classical LP recordings.

The music sounds so open, so elegant & transparent. Also very quiet background at full volume pot setting & TT spinning. Of coure, one should never expect chest punching heavy sound levels due to its low O/P voltage. But the quality of music is totally something else, not those mult-staged phono-preamp can touch...... until one listen to it.

We want quality music, NOT quantity music like a juke box, right?

Guss what triode I used????? NO pentode, please, which sounds "aweful" vs triode.

c-J

 

[cheap-Jack]

Hi.

 

What do you WANT to tell?

c-J

[guest78998]

Hi.
What do you WANT to tell?

c-J

Hey, I'm just a new young guy here looking to learn, but there is no need for negativity in this forum.

[rbwalt]

better get use to it. it abounds just about everywhere in the world of high end audio. some for the best and some for the worst.