Cadorman
Ambassador of the Catocaster
How far are you guys from Benicia? I have a cousin there I need to go visit once I finish up with my vaccinations.
High Voltages After Headfirst Origin 50 Mod
- Thread starter Inspector #20
- Start date
syscokid
Ambassador of War & Peace
Benicia is just north of San Francisco and about another 4 1/2 hours from me and about 9 hours from El Roberto.
Amp Mad Scientist
Ambassador of Heresy
Well, if there was a schematic I'd probably do it.
But until we either get one or draw one I'm thinking probably not.
I mean how can I modify it without knowing what's being modified?
But until we either get one or draw one I'm thinking probably not.
I mean how can I modify it without knowing what's being modified?
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Thanks, Man!!! I didn't know that!
syscokid
Ambassador of War & Peace
I watched enough of the Headfirst loop install video, and it shows that the new fx loop board is added over the existing amp's pcb. The new fx loop pcb's input and output jacks are first removed then the new board is hardwired to the amp's original in and out fx loop jacks. There should be 4 more wired connections after that. One for grounding the new board's circuit. One for the power. One after the tonestack. And one before the phase inverter.
Might have to drill one new hole for the fx loop bypass switch... if you want to have one at all!
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OP
You guys are super smart....
I don't have bypass at all. The FX loop comes online when you plug in the footswitch. I would say that whichever is easiest would be best.
syscokid
Ambassador of War & Peace
Ah, ok then... Instead of wiring from the new loop board to the new bypass switch, I would think that you simply wire to the footswitch jack instead... maybe...
OP
Ah, ok then... Instead of wiring from the new loop board to the new bypass switch, I would think that you simply wire to the footswitch jack instead... maybe...
This is all I know for sure...you cannot use the FX loop (bone stock) unless the footswitch is plugged in. The footswitch has two buttons, FX and BOOST.
OP
@syscokid , @Amp Mad Scientist ...
I just reached out to the Headfirst fellow via email and asked some specifics about footswitch function, i.e., can gain still be reduced with the footswitch???
Also asked about the FX loop function after the Headfirst modification, i.e., is it still footswitch dependent???
Personally, I see no benefit to how Marshall made the loop non-functional unless the footswitch is plugged in.
I was thinking that, if the FX loop doesn't require the extra footswitch button, could that be used for something else???
I also asked his thoughts on shielding the box against EMI/RFI.
Also, since my amp runs pretty much all day long at work, I asked about the feasibility of a high performance, low noise PC fan.
I'll post up his responses in this thread...
I just reached out to the Headfirst fellow via email and asked some specifics about footswitch function, i.e., can gain still be reduced with the footswitch???
Also asked about the FX loop function after the Headfirst modification, i.e., is it still footswitch dependent???
Personally, I see no benefit to how Marshall made the loop non-functional unless the footswitch is plugged in.
I was thinking that, if the FX loop doesn't require the extra footswitch button, could that be used for something else???
I also asked his thoughts on shielding the box against EMI/RFI.
Also, since my amp runs pretty much all day long at work, I asked about the feasibility of a high performance, low noise PC fan.
I'll post up his responses in this thread...
OP
@syscokid , @Amp Mad Scientist ,
Question...what power tubes would you collectively recommend in this amp for longevity???
I've heard people say KT77 and/or 6CA7's are more durable, and others say none are any more durable than the other.
Thoughts????
Question...what power tubes would you collectively recommend in this amp for longevity???
I've heard people say KT77 and/or 6CA7's are more durable, and others say none are any more durable than the other.
Thoughts????
Amp Mad Scientist
Ambassador of Heresy
I would say tubes like Svetlana are made to last longer.
Tubes from China won't last very long...
The circuit may need to be changed to adjust the bias correctly, tubes are not easily interchangeable.
I have been disappointed in EHX tube matching many times...they have sent mismatched tube sets over and over again.
I probably won't buy any more of the EHX fake 6CA7s / EL34s.
I would prefer the bottom end of the 6L6 or 5881 (same basic tube). It sounds more hi-fi.
But again I need to re-bias the amp to accommodate a 6L6. Not interchangeable, without altering the bias circuit.
And when they start calling a 6550 the same as a KT88, it only makes me doubt them more.
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OP
I apologize for all the questions, but I know little about any of this and I'm eager to learn.
Cadorman
Ambassador of the Catocaster
I actually had the glass crack on a 90's Winged C a few months back. Bummed me out. I really liked the sound of those. I was lucky to find it right away. It was popping fuses every time I tried to come off stand by.
I mostly have the Mullard reissue EL34s in my amps. They seem to have good bottom end and bias easily. I used them in my Origin 50H when I had it.
I have a set of E34Ls as well. They are nice, but you may run out of bias adjustment with these.
I mostly have the Mullard reissue EL34s in my amps. They seem to have good bottom end and bias easily. I used them in my Origin 50H when I had it.
I have a set of E34Ls as well. They are nice, but you may run out of bias adjustment with these.
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I got these...
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Marshall Origin Stock Internal Images - 9 Photos:
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Headfirst Modifications Completed Part I - 6 Photos:
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Headfirst Modifications Completed Part II - 6 More Images:
