High Voltages After Headfirst Origin 50 Mod

@syscokid now has all the resistors, diodes, capacitors and switch(es) from Mouser in stock.

I have the PCB FX board on order from Headfirst Amplification in Australia.
 
Robert Herndon said:
Transformer brand makes absolutely no difference to me. Here's a week's earnings from a Marshall Origin 50 watt head...

Could you earn more with a more expensive Transformer???

Nope...

View attachment 67742
Click to expand...
I can verify that most transformer "upgrades" don't accomplish anything.

This has numerous reasons...but mostly because the way that the circuit of the amp is designed, you have to change the circuit to get anything more out of a transformer.
It's not just the transformer that does it....it's the circuit of the amp that makes far more difference than a transformer alone.
(most people said that the transformer upgrade didn't make any difference.)
And while some transformers "are" better, the circuit limits the performance- making many transformer swaps pretty useless.
 
I was "absent" for the duration of this thread, for which I apologize.
Great job researching this Robert, you've done well.
One thing I've noticed about the Headfirst Amplification mods, from this Origin mod & other of his amp mods on the web is that they are pretty standard "tried & proven" fare & not his design per se. Of course, a good many people do this.
This Origin modification is relatively simple stuff. Aside from converting the V2 circuitry to the commonly used Marshall gain stage & cathode follower (slightly modified with a (V2a) cathode 22uf "fat cap" bypass & (V2b) cathode load 470pf bypass), then relocating the tone stack to be cathode follower driven, the rest pretty much has its origins in the often copied Josse mods.

Again, great job researching this Robert. For anyone wanting to do this modification, all the necessary info is contained within this thread.

Robert Herndon said:
@syscokid now has all the resistors, diodes, capacitors and switch(es) from Mouser in stock.
Click to expand...
If our good buddy @syscokid is doing the modifications for you I'm sure he'll do a great job with decent soldering, without scorching the C42 capacitor with the soldering iron (as seen in one of the pics you posted), & most likely with the amp not having the extraneous noise level heard from the amp in the video clip posted.

Early in this thread @Robert Herndon asked "what is fixed bias," or something to that effect.
As I don't feel this has yet been properly answered, here goes;

Fixed bias indicates that a negative voltage is applied to a tube's control grid in order to obtain the tube's quiescent, or "no signal" operating point, or "bias".
Whether that negative voltage's "supply" is adjustable (by means of a trimpot etc, to facilitate tube changes) or not, is irrelevant.
Also irrelevant (at least as far as guitar amps go) is the "class" of operation (single ended class A, class A push pull, class AB1).
Just because "most" class A amps are "cathode biased" does not at all mean tubes operating in class A HAVE to be cathode biased (class A most definitely can be fixed bias), & likewise, just because an amp is a class AB1 type does not mean it HAS to be "fixed bias".
A classic example of the latter is the Vox AC30, a cathode biased class AB1 type amp.

As a side note, tubes operating in class AB2 & class B cannot be cathode biased, but the doesn't apply to the greatest bulk of guitar amps. Cheers
 
Last edited:
ivan H said:
I was "absent" for the duration of this thread, for which I apologize.
Great job researching this Robert, you've done well.
One thing I've noticed about the Headfirst Amplification mods, from this Origin mod & other of his amp mods on the web is that they are pretty standard "tried & proven" fare & not his design per se. Of course, a good many people do this.
This Origin modification is relatively simple stuff. Aside from converting the V2 circuitry to the commonly used Marshall gain stage & cathode follower (slightly modified with a (V2a) cathode 22uf "fat cap" bypass & (V2b) cathode load 470pf bypass), then relocating the tone stack to be cathode follower driven, the rest pretty much has its origins in the often copied Josse mods.

Again, great job researching this Robert. For anyone wanting to do this modification, all the necessary info is contained within this thread.


If our good buddy @syscokid is doing the modifications for you I'm sure he'll do a great job with decent soldering, without scorching the C42 capacitor with the soldering iron (as seen in one of the pics you posted), & most likely with the amp not having the extraneous noise level heard from the amp in the video clip posted.

Early in this thread @Robert Herndon asked "what is fixed bias," or something to that effect.
As I don't feel this has yet been properly answered, here goes;

Fixed bias indicates that a negative voltage is applied to a tube's control grid in order to obtain the tube's quiescent, or "no signal" operating point, or "bias".
Whether that negative voltage's "supply" is adjustable (by means of a trimpot etc, to facilitate tube changes) or not, is irrelevant.
Also irrelevant (at least as far as guitar amps go) is the "class" of operation (single ended class A, class A push pull, class AB1).
Just because "most" class A amps are "cathode biased" does not at all mean tubes operating in class A HAVE to be cathode biased (class A most definitely can be fixed bias), & likewise, just because an amp is a class AB1 type does not mean it HAS to be "fixed bias".
A classic example of the latter is the Vox AC30, a cathode biased class AB1 type amp.

As a side note, tubes operating in class AB2 & class B cannot be cathode biased, but the doesn't apply to the greatest bulk of guitar amps. Cheers
Click to expand...
Schooled... :cheers:
 
ivan H said:
I was "absent" for the duration of this thread, for which I apologize.
Great job researching this Robert, you've done well.
One thing I've noticed about the Headfirst Amplification mods, from this Origin mod & other of his amp mods on the web is that they are pretty standard "tried & proven" fare & not his design per se. Of course, a good many people do this.
This Origin modification is relatively simple stuff. Aside from converting the V2 circuitry to the commonly used Marshall gain stage & cathode follower (slightly modified with a (V2a) cathode 22uf "fat cap" bypass & (V2b) cathode load 470pf bypass), then relocating the tone stack to be cathode follower driven, the rest pretty much has its origins in the often copied Josse mods.

Again, great job researching this Robert. For anyone wanting to do this modification, all the necessary info is contained within this thread.


If our good buddy @syscokid is doing the modifications for you I'm sure he'll do a great job with decent soldering, without scorching the C42 capacitor with the soldering iron (as seen in one of the pics you posted), & most likely with the amp not having the extraneous noise level heard from the amp in the video clip posted.

Early in this thread @Robert Herndon asked "what is fixed bias," or something to that effect.
As I don't feel this has yet been properly answered, here goes;

Fixed bias indicates that a negative voltage is applied to a tube's control grid in order to obtain the tube's quiescent, or "no signal" operating point, or "bias".
Whether that negative voltage's "supply" is adjustable (by means of a trimpot etc, to facilitate tube changes) or not, is irrelevant.
Also irrelevant (at least as far as guitar amps go) is the "class" of operation (single ended class A, class A push pull, class AB1).
Just because "most" class A amps are "cathode biased" does not at all mean tubes operating in class A HAVE to be cathode biased (class A most definitely can be fixed bias), & likewise, just because an amp is a class AB1 type does not mean it HAS to be "fixed bias".
A classic example of the latter is the Vox AC30, a cathode biased class AB1 type amp.

As a side note, tubes operating in class AB2 & class B cannot be cathode biased, but the doesn't apply to the greatest bulk of guitar amps. Cheers
Click to expand...

Anything you see in the mod strategy that you might recommend we do differently????
 
So, dumb question, but is the Origin 20 actually any good?

Bear in mind, I care next to nothing for super high-gain sounds, so the Origin’s ability to do that is not really on my radar. But, how does it sound as a medium to hard rock platform?
 
actually @smitty_p I been playing my Origin 20 most the last couple hours....... its a stellar amp for the OLD marshall tone plexi "ish" (lord the real plexi owners are going to have a :poo: fit) ....
ISH people settle DOWN!

it doesnt do metal modern -- as a MATTER OF FACT I traded the DSL40head for this Origin 20 head ....becasue -- frankly I dont do a lot of high gain modern metal ... more blues rock and improve jazz...... the origin is AWESOME for that --
you can throw a metal pedal in front of it and "get there" ......but why you have a BANDIT if you want punch your face out gain

Im really JUST delving into the origins tones.....

I have a Marshall Master LEad 12 that has SPOILED me on vintage 70's Marshall yumminess.......... (man that amp sounds good)
 
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