Modulus Amps Marshbar

[SpeedTrip]

I thought I'd post updates on the kit I've just purchased for Modulus Amps in Scotland as I noticed a couple of people asked about their kits.

I've only just opened the box of parts so Ill try and photo key stages as I go with the build. First impression are good. Micheal the owner of Modulus has been helpful both pre and post purchase. Ill keep you all informed

[SpeedTrip]

The kit is easy to dry assemble using the layout on the website ( you don't get schematic but you can work it out). I opted for combo version and Micheal the owner was happy to flip the faceplates. Only thing I had to do was reverse the toggle switch which I did by taking it apart.

The only other prep was to pop rivet the sides. It comes with holes on the out plates so it easy to square off and drill them.

I'll post more as build progresses.

[Bieworm]

Looking good!
You know it’s easier to wire the power supply and heaters with the turretboard out of the chassis?
Personally I don’t like the predrilled matrix boards. They limit the dimensions and look silly IMHO. But that’s mostly because I design my own layouts. They’re not inferior though!

[SpeedTrip]

Process was board out, wired up the main switch and circuit.

With board on the bench wired up cabling to board and I've just installed that now. All easy to do with a printed diagram by the side.

Next step is to wire the board connectors to the pots, valve bases and jacks ( though I'll leave the speaker jacks out while I wire heaters).

[Bieworm]

Process was board out, wired up the main switch and circuit.

With board on the bench wired up cabling to board and I've just installed that now. All easy to do with a printed diagram by the side.

Next step is to wire the board connectors to the pots, valve bases and jacks ( though I'll leave the speaker jacks out while I wire heaters).

Although I've been there too, building an amp without schematic, I wouldn't feel comfortable anymore without one. The layout looks like a no-brainer, but any mistake and you'll have a hard time finding it.
Is it an intentional strategy to pull the wires through the holes in the turretboard? Again, when there is a mistake in the wiring it will be hard to troubleshoot and correct things. If it's a "look" thing, there's nothing wrong with wires over the board IMHO.
I would not wire the heaters with the board in either. The heater wiring is a meticulous job and I need as much comfort as possible to wire those.
I don't want to be all negative about your build, I'm just stating that you might run into trouble and have a hard time solving it. I have no idea about your experience, so I might just as well be on the wrong track here...

[SpeedTrip]

To answer your questions comments

I worked out my own schematic from the circuit before buying and it is helpful to have one.

I used the through board very deliberately. The kit uses this process but I also noted one of this forum experts advises that you can use this technique to anchor the wires so even if the solder fails the wires will not come adrift. I also find it's very easy to trace this circuit across the diagram.

If there is a fault Michael does offer a fault support if you've built as per his kit. Other reason to keep it logical.

Experience, this is my second amp build. The last one was 20 years ago from a Guitar Magazine kit based on a Cornell design. But I'm more than happy fault finding and circuit tracing. Many happy hours commissioning H and V plants during my career.

Hope that answers your worries. I'll keep posting and look forward to comments

[SpeedTrip]

Oh while I think, what's your experience with the capacitor foil polarity. I was planning to identify the "direction" of the unmarked capacitors before install. Is it worth doing?

[Bieworm]

Oh while I think, what's your experience with the capacitor foil polarity. I was planning to identify the "direction" of the unmarked capacitors before install. Is it worth doing?

I always do that. There’s no downside on doing so. I tryto harvest the most success when building, and avoid regretting not doing it. And the fun of that process ofcourse

[SpeedTrip]

I wired up the board to the pots etc leaving the components off the board. This allowed me to complete continuity checks on the wiring as I went along.

Just about to start putting the components on the board.

You'll note the heater wires are parallel rather than twisted. Michael advocates either way but shows parallel in his wiring phones. So I decided to try it this way.

[JMPGuitars]

Twisted or parallel doesn't matter. What matters is that the wire can't move. I don't know if that's enough shrink wrap for that purpose, but you can add carefully placed zip ties if needed.

[SpeedTrip]

Wiring completed and I went through careful start up .
No humm being caused by heaters. Do get a little of the gain hum when you click the switch to change the cathode resisters and capacitors.

It's sounds great through a Jenson 10 inch 8ohm c10q but even better through marshall half stack 4x75watters @ 16 ohm.

Next stage is build a cabinet to house combo and probably investigate foot switching for the cathode switching

[guitarmike2107]

Process was board out, wired up the main switch and circuit.

With board on the bench wired up cabling to board and I've just installed that now. All easy to do with a printed diagram by the side.

Next step is to wire the board connectors to the pots, valve bases and jacks ( though I'll leave the speaker jacks out while I wire heaters).

Although I've been there too, building an amp without schematic, I wouldn't feel comfortable anymore without one. The layout looks like a no-brainer, but any mistake and you'll have a hard time finding it.
Is it an intentional strategy to pull the wires through the holes in the turretboard? Again, when there is a mistake in the wiring it will be hard to troubleshoot and correct things. If it's a "look" thing, there's nothing wrong with wires over the board IMHO.
I would not wire the heaters with the board in either. The heater wiring is a meticulous job and I need as much comfort as possible to wire those.
I don't want to be all negative about your build, I'm just stating that you might run into trouble and have a hard time solving it. I have no idea about your experience, so I might just as well be on the wrong track here...

Pulling the wires to the top side of the board means you can see where they are connected and inspect the quality of the connection once the board is in place.
Going through the hole provides support for the wire and prevents it breaking during the install process and the lifetime of the amp.

Don't make connections on the underside of a turret board, you may forget they are there when modding a few years later on and connect ground to b+ - Ask me how I know that.

The wires are colour coded, so cathodes are yellow, plates are blue etc. So it is very easy to follow the signal run and make sure wires are going to the right place with a quick inspection.

When running heaters like SpeedTrip has done it is better to do it last, if you are running them twisted in the corner then do them first.

I normally fit components on the board before installing the board in the amp, it make soldering connections easier.

[Bieworm]

“
Pulling the wires to the top side of the board means you can see where they are connected and inspect the quality of the connection once the board is in place.
Going through the hole provides support for the wire and prevents it breaking during the install process and the lifetime of the amp.”


Leo didn’t run wires through holes either. The last thing his amps can be blamed for is reliability issues or not passing the test of time. You should aim for short wire runs and they will probably stay where they are until they get moved manually. Builders better spend more time on making good connections and solder joints instead of focussing on optical properties. And whether thát’s better looking is debatable

[guitarmike2107]

Of course you can build your amps any way you want. I agree the quality of the connection and soldering is most important.

Leo did actually run some wires through holes in the board. Helps keep them in place.

Here is a Marshall 60s JMP50, wires through holes in the board.

[Bieworm]

Of course you can build your amps any way you want. I agree the quality of the connection and soldering is most important.

Leo did actually run some wires through holes in the board. Helps keep them in place.

Here is a Marshall 60s JMP50, wires through holes in the board.

Ain’t nothing wrong with the “through a hole” thing. I wouldn’t.. for a number of reasons. But I doubt that this is often the cause of trouble in an amp built with quality parts and dito soldering job. It might help for some though.
As for Leo doing this .. well yeah, but mostly for connections in the middle of his eyelet board, supporting a wire that starts far away.
I consider the “all wires through a hole” a nerdy manoeuvre. That’s not a bad thing though. I like nerdy stuff. That makes me feel more normal

[Tomten]

I thought I'd post updates on the kit I've just purchased for Modulus Amps in Scotland as I noticed a couple of people asked about their kits.

I've only just opened the box of parts so Ill try and photo key stages as I go with the build. First impression are good. Micheal the owner of Modulus has been helpful both pre and post purchase. Ill keep you all informed

Is it a high gain amp kit ? any plans for different type of mods on it ?

[SpeedTrip]

Here is the link to the sample sounds (Micheal the owner of Modulus having fun)

https://fb.watch/qiSisKh8QC/

Yep - high gain

No plans to do anything with it apart from build a cab

[EvilTed]

Just found this and the pics answered about 2 of my questions. Such perfect timing.

Fired mine up this morning and very impressed with this little amp. Love the sound.

[SpeedTrip]

I've very lucky. I've a friend who's built me a box to house it in. Hope I can do him justice with covering it

[Bieworm]

I've very lucky. I've a friend who's built me a box to house it in. Hope I can do him justice with covering it

Is it your first tolex job? You might wanna practice the corners and rounded cutouts on a scrap piece before doing the actual job. Good results take practice.