DEMO Marshall Tube Pre-amp build 🤘🏼

This post contains an audio or video demo

Dan0h

Well-known member
Success! After building my last tube preamp box for the Blackface sound I thought it would be only fair to do a Marshall build as well. And it does not disappoint.

Using Rob Binette’s JCM 800 schematic I just built the pre-amp section on one of @PedalPCB protoboards and used one of the Hv power supply boards. I really like these Hammond 1456 enclosures. Just enough room to work with. Obviously this would look much cleaner with a plug and play pcb but I like the challenge of laying things out by hand it’s like a puzzle maze to get it all together. This thing is a spaghetti fest inside lots of room for improvement but absolutely zero oscillating and sounds really nice.

Anyway, hope it inspires someone to build something fun. I will try to record a more in-depth demo but for now here is a quick comparison between my Golden Falk and this. Both very awesome sounding pedals. This just has that 5-10% more goodness that tubes seem to give in the low-mid warm ness and clarity. Only changes I’d make is adding some more attenuation at the output. It’s so FALKing loud but it plays very well with the other pedals on my board. I stuck with 9volts as 12volts sounded cool but only by a touch and the tubes ran much hotter at 12v. Oh and about 240v for the tubes.

🤘🏼Quick sample 🤘🏼
BA5FA11C-EA13-4C54-B9D4-EC1CAB888339.jpeg AF3577D7-5059-48F1-9F61-D36FDD0678F2.jpeg 34517814-CFC4-416E-8B03-A0305AC017F4.jpeg 22F73037-5D6A-45B1-A05D-E1F5C9C816A7.jpeg 58CEC916-CF30-48DD-889F-2A4F7DA2DE28.jpeg 731512CB-504E-4CF7-9FCF-881085AE44DD.jpeg 88D8C287-C347-4C3E-98D0-D5C2E3EEA65A.jpeg 642A26B3-7B82-4E76-86B4-B8B523DFE9CE.jpeg
 

Attachments

  • 36FCE4A8-5052-4439-AC6F-3A0A054FB21B.jpeg
    36FCE4A8-5052-4439-AC6F-3A0A054FB21B.jpeg
    387.2 KB · Views: 67
  • 37C09642-0078-4F64-8A38-AA56EF376E38.jpeg
    37C09642-0078-4F64-8A38-AA56EF376E38.jpeg
    892.5 KB · Views: 65

Brett

Well-known member
This is awesome @Dan0h! It seems that between this and the BlackVibe, you're going to have a pretty nice range of tone covered!
 

Dan0h

Well-known member
This is awesome @Dan0h! It seems that between this and the BlackVibe, you're going to have a pretty nice range of tone covered!
Thank you, and agreed. They both do their specific sounds really well. And they both have a lot of flexibility.
 

Synchrony Pedalworks

Well-known member
Do you think an AC30 preamp could be adopted to this format? I have wanted to build an AC30, but don’t have the room for another amp. This type of set up might give the feel of the AC30 with out the bulk!

It also looks fantastic and inspirational!
 

Dan0h

Well-known member
Do you think an AC30 preamp could be adopted to this format? I have wanted to build an AC30, but don’t have the room for another amp. This type of set up might give the feel of the AC30 with out the bulk!

It also looks fantastic and inspirational!
I don’t see why not. These are just the preamp sections (color and tone). I’ve always wanted to try a Vox but haven’t tried one yet, so I don’t know how much of their color and tone comes from their preamp section or if it comes from the power amp section.

Because Marshall was founded on the Fender platform and I have a Fender tube power section (my amp) both of these builds have worked really really well with my rig. They are no different than any other amp in a box pedal. But they use tubes instead of transistors and have 200+v instead of 9-12.

I’ve said before you can get pretty close to the same thing using just normal components, and there are an endless supply of straight forward PCBs available to search and find what works best. These types of builds are more for the love and fun of it. They have satisfied my GAS to build a full amp, at least for now….
 

Dan0h

Well-known member
Very cool. What other pedals do you have on your board?
Thanks. This is my daily driver board and it brings a shit load of happy to my day.

From top left to bottom right in that photo:
Sproing
Total Recall -DMM
JCM 800
BlackVibe
Golden Falk- replaced with a Trembling Loon
Mojito
Pro-10 Blue side
Parentheses.
 

chip

Active member
That's cool. I've never messed with tube stuff, figuring I'd zap myself. And from the size of those parts, it looks like they're running at "real" voltage. How do you keep the tubes cool in there? Or is that not a huge deal?
 

Dan0h

Well-known member
That's cool. I've never messed with tube stuff, figuring I'd zap myself. And from the size of those parts, it looks like they're running at "real" voltage. How do you keep the tubes cool in there? Or is that not a huge deal?
The enclosure has vent cutouts on the back and the bottom so enough air flow gets through. The plates are getting 240volts but the heaters are at 9v. They are warm but not hot enough to cause any issues. When running at 12volts they get considerably hotter to the point that it might cause issues for anything close to the tube and this enclosure might not fly. Not sure and not wanting to test that out since the sound difference is almost non-audible. Photo of the back vents.
58B62C3B-5134-4EE3-9CC4-700F76318E0C.jpeg
 

Vurguuz

New member
Does the true bypass wiring generate a popping noise when working the 3pdt switch? The designer of Kingsley pedal preamps doesn't use true bypass, citing this reason.
 

Attachments

  • Capture.JPG
    Capture.JPG
    109.1 KB · Views: 12

Dan0h

Well-known member
Does the true bypass wiring generate a popping noise when working the 3pdt switch? The designer of Kingsley pedal preamps doesn't use true bypass, citing this reason.
Neither this build or the Blackvibe I built have popping and both are wired true bypass.
 

Fizz

Active member
Success! After building my last tube preamp box for the Blackface sound I thought it would be only fair to do a Marshall build as well. And it does not disappoint.

Using Rob Binette’s JCM 800 schematic I just built the pre-amp section on one of @PedalPCB protoboards and used one of the Hv power supply boards. I really like these Hammond 1456 enclosures. Just enough room to work with. Obviously this would look much cleaner with a plug and play pcb but I like the challenge of laying things out by hand it’s like a puzzle maze to get it all together. This thing is a spaghetti fest inside lots of room for improvement but absolutely zero oscillating and sounds really nice.

Anyway, hope it inspires someone to build something fun. I will try to record a more in-depth demo but for now here is a quick comparison between my Golden Falk and this. Both very awesome sounding pedals. This just has that 5-10% more goodness that tubes seem to give in the low-mid warm ness and clarity. Only changes I’d make is adding some more attenuation at the output. It’s so FALKing loud but it plays very well with the other pedals on my board. I stuck with 9volts as 12volts sounded cool but only by a touch and the tubes ran much hotter at 12v. Oh and about 240v for the tubes.

🤘🏼Quick sample 🤘🏼
View attachment 40849View attachment 40850View attachment 40851View attachment 40852View attachment 40853View attachment 40858View attachment 40857View attachment 40856
So cool... my reason for learning to build pedals was to eventually build amps. I never thought about anything like this.. it will have to be my logical next step when I get good at building pedals to then move here to building pre-amps before I start building amps. The 800 is my favorite.
 

simonbratton

New member
Success! After building my last tube preamp box for the Blackface sound I thought it would be only fair to do a Marshall build as well. And it does not disappoint.

Using Rob Binette’s JCM 800 schematic I just built the pre-amp section on one of @PedalPCB protoboards and used one of the Hv power supply boards. I really like these Hammond 1456 enclosures. Just enough room to work with. Obviously this would look much cleaner with a plug and play pcb but I like the challenge of laying things out by hand it’s like a puzzle maze to get it all together. This thing is a spaghetti fest inside lots of room for improvement but absolutely zero oscillating and sounds really nice.

Anyway, hope it inspires someone to build something fun. I will try to record a more in-depth demo but for now here is a quick comparison between my Golden Falk and this. Both very awesome sounding pedals. This just has that 5-10% more goodness that tubes seem to give in the low-mid warm ness and clarity. Only changes I’d make is adding some more attenuation at the output. It’s so FALKing loud but it plays very well with the other pedals on my board. I stuck with 9volts as 12volts sounded cool but only by a touch and the tubes ran much hotter at 12v. Oh and about 240v for the tubes.

🤘🏼Quick sample 🤘🏼
View attachment 40849View attachment 40850View attachment 40851View attachment 40852View attachment 40853View attachment 40858View attachment 40857View attachment 40856
This build looks awesome! I've been toying around with the idea of doing something similar with either a JCM 800 or OR120 preamp so this has given me the push to finally do it. Quick question about the presence control. How did you go about wiring it up given that it's usually tied into the negative feedback loop? I've seen some implementations on JCM 800 JFET pedals, but not sure how it's translated to this preamp build. Would love to hear your thoughts as I couldn't tell from the photos. Also, have you found the Nixie power supply pretty stable and not introducing any noise? Would love to not have to include filter capacitors to the HV rail.
 
Top