High Voltages After Headfirst Origin 50 Mod

syscokid said:
Yeah, it's a little different than the Origin 20. In this video, Jason never did post the new voltages hitting the first two preamp tubes. Maybe at his website there'll be more documented info on modding the Orgy 50. And if a new fx loop board needs to be added, the module for the loop will be located about a 1/2" different compared to the O-20 modding tutorial.
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I believe that there will be a "proper video" when the amp is done.
 
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Just found this over at the Marshall Forum.

Seems to be correct as I remember my amp.

Question: Has any tech here checked part values in the PI and around the EL34s?
Hopefully "standard Marshall values" but as we've seen with the Origin Series one never knows...
 

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Best high gain mod of the Origin 50 H that I've heard this far.

Don't know the specs of the mod but I'd guess that it's similar to the Headfirst mod with the added diode clipping.
I know that he adds a 2:nd gain control (instead of the tilt control) and tweaks the presence circuit as well as the pi/power section a bit.

Not a sound that I really need myself, but damn it sounds impressive!

 
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Polifemo said:
Just found this over at the Marshall Forum.

Seems to be correct as I remember my amp.

Question: Has any tech here checked part values in the PI and around the EL34s?
Hopefully "standard Marshall values" but as we've seen with the Origin Series one never knows...
Click to expand...
As far as I know, the PI is half tube / half mosfet.
The mosfets are used to scale the power output limit. I don't know what the schematic is exactly.
Apparently the head first modification disables the power scaling, but why that is without a schematic we may never know.
 
Amp Mad Scientist said:
As far as I know, the PI is half tube / half mosfet.
The mosfets are used to scale the power output limit. I don't know what the schematic is exactly.
Apparently the head first modification disables the power scaling, but why that is without a schematic we may never know.
Click to expand...
Regarding the 50 watt head the power amp is said to be "basically standard Marshall values" but of course the power scaling components are in there "somewhere".
 

Attachments

Polifemo said:
Best high gain mod of the Origin 50 H that I've heard this far.

Don't know the specs of the mod but I'd guess that it's similar to the Headfirst mod with the added diode clipping.
I know that he adds a 2:nd gain control (instead of the tilt control) and tweaks the presence circuit as well as the pi/power section a bit.

Not a sound that I really need myself, but damn it sounds impressive!

Click to expand...

@Don O
 
Robert Herndon said:
@Don O
Click to expand...
Yeah, I’m using the Origin comparison (the Ivanberg vs stock) to motivate me to get my DAW hardware and software operational. I spent Saturday trying to get my RME interface to talk to Reaper but no joy. So I started with the basics and got the Mackie mixer through its ASIO driver to record a track but I couldn’t get the playback out to the JBL powered monitors connected to the Mackie.

Meanwhile I’m hanging mural wallpaper sections (honey dos). The wife is gonna be involved in a charity event Thursday and Friday so I should have some studio time coming up to sort the DAW out. Stay tuned !
 
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Amp Mad Scientist said:
Apparently the head first modification disables the power scaling, but why that is without a schematic we may never know.
Click to expand...
The power scaling is not disabled. But trying to use it at less than 100% is useless. Half of V2 used to set up the amp's original fx loop circuit. The HF mod reconfigures that "half" into another gain stage instead. The amp's power scaling is incompatible with the modded circuit.


Polifemo said:
Regarding the 50 watt head the power amp is said to be "basically standard Marshall values" but of course the power scaling components are in there "somewhere".
Click to expand...
We would need to see Marshall's schematic of the power supply. Unfortunately, none of these attachments show this. Does Marshall release their current schematics to authorized service techs?
 
syscokid said:
The power scaling is not disabled. But trying to use it at less than 100% is useless. Half of V2 used to set up the amp's original fx loop circuit. The HF mod reconfigures that "half" into another gain stage instead. The amp's power scaling is incompatible with the modded circuit.



We would need to see Marshall's schematic of the power supply. Unfortunately, none of these attachments show this. Does Marshall release their current schematics to authorized service techs?
Click to expand...
OK...the power scale is useless...because of incompatibility.
The only way to get the schematic is to draw one.

They are not releasing the schematics because they don't want Behringer to copy their design...

Eventually there will be schematics.
But the Marshall One Watt design was the same way, no schematics.
 
67plexi said:
I think Marshall needs to address the major design flaw issues first on the Origin amps.


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I have seen this video...
and I don't think there is any major design flaw.

The volume does not go to "0"
when the volume is turned down. That is true for many amplifiers including several fender amps.
That is normal.

I think this guy at Pisonic is assuming a lot of things, based purely on assumptions and imagination.
 
I like my Origins the way they came from Marshall, yes I use a pedal for more dirt. If I need higher gain I use my Dsl40c’s, no mods needed.
 
See?
In tube amps:
when 2 sections of a 12AX7 are used for audio, sound can bleed from 1 section to the other section.
That is why the volume won't go to zero.

2. When 2 circuit tracks are side by side, audio can bleed between the circuit tracks.
That is normal.
That is why audio bleeds through.

3. When 2 capacitors are side by side, audio can pass between the spaces on the board.
Audio can transfer from 1 capacitor to the other, through the air space.
This happens all the time in tube amps.

Two capacitors side by side -
a third capacitor forms in the air space between them. The closer they are, the more bleeding can occur.

Many amplifiers do not go all the way to "zero" volume.
Many of them bleed audio when the volume is set to zero.
I do not consider this a design defect.
It happens because of the circuit layout.
 
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syscokid said:
The power scaling is not disabled. But trying to use it at less than 100% is useless. Half of V2 used to set up the amp's original fx loop circuit. The HF mod reconfigures that "half" into another gain stage instead. The amp's power scaling is incompatible with the modded circuit.



We would need to see Marshall's schematic of the power supply. Unfortunately, none of these attachments show this. Does Marshall release their current schematics to authorized service techs?
Click to expand...
I’m guessing here, but I don’t believe that they are sharing the schematics with anyone...
 
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