IM SO CONFUSED

[ivan H]

In general, is there a difference in performance between these two types of power tubes?


So, most of us EL34 users are operating these tubes as tetrodes? Now I feel like I've been short-changed for the last 40 years...

Yes, same with EL84's. With a good many amps (fixed bias types), it's relatively easy to wire them to actual pentode operation though. The power tube sockets just need to be rewired to seperate the suppressor grid's pin from the cathode's pin (which stays grounded). A negative voltage derived from the negative bias supply is then connected to the suppressor grid pins on the sockets. Check bias. It will alter power amp characteristics

In this configuration, EL34 is a pentode. The bias negative voltage is tied to the suppressor grid.
This decreases the efficiency of the tube.

Other way 'round. With the suppressor tied to the cathode it does nothing to suppress secondary emission (it's inactive). The whole purpose behind adding the suppressor grid is to suppress secondary emission (this is why it's called a suppressor grid), which it does by carrying a potential that is negative with respect to the electrons (& thus the cathode) passing through the valve. Cheers
Edit:
Think about it,,, an element in a tube (the suppressor grid) won't repell electrons that have the same potential as it. Electrons carry a negative charge, so to repell them the suppressor grid must be "more" negative than them, just as the control grid has to be "more" negative than the electrons to repel them. Cheers

 

[Amp Mad Scientist]

Gotcha, appreciate that! So by that logic then, a Traynor could operate with something like a KT77 since its a pentrode as well, but a Kt66 would not work either since its a beam tetrode like the 6CA7?

You can only use pentode tubes, with a separate suppressor grid.

 

[Clockworkmike]

And that is why i am no tech guru by any stretch nor would dare ever claim to be! lol i really do have the utmost respect to guys like you all here that know the inner workings of these things. I pretend to play them but wont even try to put on a facade of how to build or properly service one minus changing a tube or biasing it lol

 

[eSGEe]

this.............DSL 15H ...........has a switch triode/pentode ...........a la mode

 

[eSGEe]

Yes, same with EL84's. With a good many amps (fixed bias types), it's relatively easy to wire them to actual pentode operation though. The power tube sockets just need to be rewired to seperate the suppressor grid's pin from the cathode's pin (which stays grounded). A negative voltage derived from the negative bias supply is then connected to the suppressor grid pins on the sockets. Check bias. It will alter power amp characteristics

Other way 'round. With the suppressor tied to the cathode it does nothing to suppress secondary emission (it's inactive). The whole purpose behind adding the suppressor grid is to suppress secondary emission (this is why it's called a suppressor grid), which it does by carrying a potential that is negative with respect to the electrons (& thus the cathode) passing through the valve. Cheers
Edit:
Think about it,,, an element in a tube (the suppressor grid) won't repell electrons that have the same potential as it. Electrons carry a negative charge, so to repell them the suppressor grid must be "more" negative than them, just as the control grid has to be "more" negative than the electrons to repel them. Cheers

and I thought I was CONFUSED in the first friggin post ............................................................................

 

[Clockworkmike]

this.............DSL 15H ...........has a switch triode/pentode ...........a la mode
View attachment 55700

Wouldnt that be easier for everything to do that from the get go? Lol i know the DSL100H/HR does that too and it can cut the power from 100w to 50w by doing so ( DSL40Cs have this too i believe?). The Silver Jubilees have a 3rd switch on the front that does that too and cuts the power in half as well.


But im guessing you'd have to have a pentode tube from the start to pull this off?

 

[eSGEe]

theres a winkie joke in this thread someplace -------

 

[Clockworkmike]

theres a winkie joke in this thread someplace -------

Got it: the dreaded tube called a 9NCHR Penetrobe. Unwieldy beast

 

[chilipeppermaniac]

Can contain every known amp type in the world.

View attachment 55677

Just add a Kemper play back unit

Dono, HEY, My sweety got me some Sony Blue tooth headphones. I tried to link it to my laptop but it apparently does not have bluetooth.

I saw a Blue tooth USB adapter thing, do you or anyone know if it is basically a plug it in and it works type thing? Or will I need to add software or some other hurdle to jump through to make it work?

 

[chilipeppermaniac]

I am sure you know the answer, Bdon. What say you?

Oh yeah, and to the rest of our members, WHERE the heck did I put my OEM Epi Humbucker pups I took out of my EPI LP Standard way back around 2014 -2016 when I installed the T Tops in it?

 

[Thatbastarddon]

Dono, HEY, My sweety got me some Sony Blue tooth headphones. I tried to link it to my laptop but it apparently does not have bluetooth.

I saw a Blue tooth USB adapter thing, do you or anyone know if it is basically a plug it in and it works type thing? Or will I need to add software or some other hurdle to jump through to make it work?

View attachment 55708

View attachment 55709

Most are just plug and play....I’ve only sought connection in the opposite direction. I like to beam from my phone to the PA....not so much the other way.

 

[Don O]

Agree, blue tooth adapters are pretty much plug and play. You do have to “pair” them to the headphones to communicate.

 

[Amp Mad Scientist]

Gotcha, appreciate that! So by that logic then, a Traynor could operate with something like a KT77 since its a pentrode as well, but a Kt66 would not work either since its a beam tetrode like the 6CA7?

Important consideration:
I know it's confusing, so follow along step by step.

Some 6CA7 is a Tetrode. The cathode is tied to the suppressor inside the bottle.
Some 6CA7 is a Pentode ! The suppressor grid and cathode are separated / not tied together inside.

[A True 6CA7 (IMHO) is separate, and is not tied inside the tube. This is a pentode.]

If you install the Tetrode 6CA7 in a Traynor or PV Windsor, it will short the bias voltage to ground.
Because the Traynor and PV Windsor was designed for the pentode output tube.

Now watch out for this, and check your manufacturer data sheets !

 

[Clockworkmike]

Important consideration:
I know it's confusing, so follow along step by step.

Some 6CA7 is a Tetrode. The cathode is tied to the suppressor inside the bottle.
Some 6CA7 is a Pentode ! The suppressor grid and cathode are separated / not tied together inside.

[A True 6CA7 (IMHO) is separate, and is not tied inside the tube. This is a pentode.]

If you install the Tetrode 6CA7 in a Traynor or PV Windsor, it will short the bias voltage to ground.
Because the Traynor and PV Windsor was designed for the pentode output tube.

Now watch out for this, and check your manufacturer data sheets !

View attachment 55719

View attachment 55721

Seriously appreciate you explaining that! I toyed with the idea of trying these out in a Marshall just to see what it sounded like but im glad to know there's different ones to look out for as clearly shown here. Didnt know that there were in fact 2 versions: tetrode and pentode!

 

[chilipeppermaniac]

Agree, blue tooth adapters are pretty much plug and play. You do have to “pair” them to the headphones to communicate.

Thanks guys, I already learned about the bluetooth pairing from my phone to my headphones. Tried to do that with the Laptop first but without the "features" it was a no go.

 

[chilipeppermaniac]

Most are just plug and play....I’ve only sought connection in the opposite direction. I like to beam from my phone to the PA....not so much the other way.

Thank you Bdon

 

[Amp Mad Scientist]

Seriously appreciate you explaining that! I toyed with the idea of trying these out in a Marshall just to see what it sounded like but im glad to know there's different ones to look out for as clearly shown here. Didnt know that there were in fact 2 versions: tetrode and pentode!

In a Marshall, pin 1 is tied to pin 8 at the socket.
You can check this with your ohm meter. Cathode and Suppressor are tied to ground in a Marshall amp at the socket.

Therefore you can use tetrode or pentode output tubes in a Marshall.
The bias supply is never hooked to the suppressor in Marshall. -------(unlike Traynor or PV)

London Power Scaling:
The suppressor is used to control the output power.
Therefore, you must always use a true pentode.
The suppressor cannot be tied to the cathode for LPS to function.

 

[Clockworkmike]

In a Marshall, pin 1 is tied to pin 8 at the socket.
You can check this with your ohm meter. Cathode and Suppressor are tied to ground in a Marshall amp at the socket.

Therefore you can use tetrode or pentode output tubes in a Marshall.
The bias supply is never hooked to the suppressor in Marshall. -------(unlike Traynor or PV)

London Power Scaling:
The suppressor is used to control the output power.
Therefore, you must always use a true pentode.
The suppressor cannot be tied to the cathode for LPS to function.

Very cool of you clearing this up! So from what im gathering here, Marshall typically connects the suppressor grid ( pin 1)
to the cathode (pin 8) in the base, where as someone like Traynor doesnt and goes with a negative bias to the suppressor grid? ( hoping im getting this right, im not savvy in this but just find it interesting honestly) What would be the advantage to something like that?

 

[chilipeppermaniac]

The suppressor cannot be tied to the cathode for LPS to function.

AMS, what is LPS?

 

[jtcnj]

I never got on well with suppressor grids; they're just always so,... negative.....

Anyway, I think it was touched on but a lot of what I have read is that power tube "sound" is more due to the circuit design it is used in, rather than the "sound" of the model of tube.

I say "more due" - the tubes themselves probably sound a bit different from one another in the same type of circuit topology (and adjusting the values to similar operating points).