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Post subject: Solid State Output Tube Driver for a SE guitar amp
Posted: Wed Nov 01, 2017 11:30 pm
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So nervous to post my question.
I'm looking up as I go once again. Consider this output stage segment from a guitar amplifier I physically built:
Image
The LND150 is an "depletion mode" MOSFET, whereas the IRF820 is a normal "enhacement mode" MOSFET. Their drains are connected to a 360vdc source (not shown).

The green section amplifies the line-level input from the FX_RCV to ~30vac. This is often called "Effects loop recovery" stage.

The red section forms a solid state "dc-coupled cathode follower" to be able to supply large amounts of current to the output stage. This helps reduce the tonality changes from using the RV7 master volume.

With guitar amplifiers, they sound incredible when the output stage is overdriven. There are several limits to how far you can push a stage though, one is blocking distortion. In this circuit, blocking distortion can be produced by the c15 capacitor discharging.

I'd like to eliminate the red section. Then, I'd like to have a transistor (or a pair of transistors) directly drive the grid on the output tube, without need coupling capacitors.

While I'm pretty new at analog design! I'm here asking this question because I don't know what I don't know! If I can get a bump in the right direction, that'd be very useful.

Thank you very much!

EDIT: The red section is actually in the amplifier to try and -prevent- blocking distortion, but eliminating the cap completely would be the most ideal solution!

EDIT: Maybe I got my terminology messed up on enhancement/depletion mode


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Post subject: Re: Solid State Output Tube Driver for a SE guitar amp
Posted: Mon Nov 06, 2017 9:50 am
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Looks like you posted same question this 5 months ago on another website. Are U a Bot?
The only other type of coupling device suitable would be an inter-stage transformer.


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Post subject: Re: Solid State Output Tube Driver for a SE guitar amp
Posted: Mon Nov 06, 2017 10:22 am
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Brings up an interesting and amusing question.
Would a bot ever admit it was a bot?

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Just think of how awesome a guitar player you could have been by now if you had only spent the last 10 years practicing instead of obsessing over pickups and roasted maple necks.


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Post subject: Re: Solid State Output Tube Driver for a SE guitar amp
Posted: Mon Nov 06, 2017 7:02 pm
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It's hard to take a post seriously when I search google images with the title of the post and its the first thing that comes up.
That site had this discussion 5 months ago. While I like helping, I'm wondering what's going on here.


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Post subject: Re: Solid State Output Tube Driver for a SE guitar amp
Posted: Mon Nov 06, 2017 7:29 pm
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BMW-KTM wrote:
Brings up an interesting and amusing question.
Would a bot ever admit it was a bot?

No,I'm a human.


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Post subject: Re: Solid State Output Tube Driver for a SE guitar amp
Posted: Wed Nov 08, 2017 10:18 am
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Oh, That explains everything!


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