Building Modern Ground Schemes (JMPGuitars_18_Watt)

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Building Modern Ground Schemes (JMPGuitars_18_Watt)

Post by davemojo »

Hi All,

that seems a post directly for Josh but obviously is for everyone lol.

I'm nearly done with that MADAMP a 15 Watts project and expectations are not that great but it is ok for a practice amp for now.

I want to build now the exact project JMPGuitars_18_Watt layout.

To be able to do that I need to create a chassis myself to adapt that layout.

I only built out of a kit so far therefore chassis holes and everything else was already predrilled and ready to be used, but now is different and is going to be more challenging

1) Unless I am not aware but I don't think I can adapt a predrilled 18 watts chassis with the above project?

2) I would go for a chassis that is plain with no holes, what type of exact driller and driller tips would be needed and I bet I would need some specific driller that best suite this purpose? There are holes that are big like the one for the filter caps or potentiometers, any advise on how to best drill them out?

3) this is for me now the most difficult part the front and rear plates those must be custom made and there are Online shops such Tube-Town that can create custom plates, however that would require some software skills to design the plate first, that is something I have never done, what's the easiest way to accomplish this for someone that is beginner?

4) For the layout I have one silly question, but I am asking myself why was done this way, there seems to be two resistors with no written value but from the color band they seems 800k Ohms, see attached, is there a reason why those 2 are represented differently with no written value?

5) It is ok to build it and post step by step photos and you could check each step? I wouldn't do that if it was not the really first time doing so :-)
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Re: Building Modern Ground Schemes (JMPGuitars_18_Watt)

Post by JMPGuitars »

davemojo wrote:
Sun 10/31/21 8:55 am
I want to build now the exact project JMPGuitars_18_Watt layout.
Which one? Lite 2b(ish)? There's a lot of projects that start with that. ;)
1) Unless I am not aware but I don't think I can adapt a predrilled 18 watts chassis with the above project?
Most of the basic projects, including the Lite 2b(ish), will fit into a standard 18W chassis. Only my larger projects require a custom chassis. I do sell a custom chassis that accommodates the larger projects if you ever go that route, it's $150 for just the chassis, but international shipping won't be cheap. I do have custom faceplates for the Tremolo TMB to match the chassis, and I will eventually have other project versions available as well.
4) For the layout I have one silly question, but I am asking myself why was done this way, there seems to be two resistors with no written value but from the color band they seems 800k Ohms, see attached, is there a reason why those 2 are represented differently with no written value?

5) It is ok to build it and post step by step photos and you could check each step? I wouldn't do that if it was not the really first time doing so :-)
All of the layouts have an accompanying SCHEMATIC. The schematic has the values written clearly. Those plate resistors are almost always 100K in all of my projects (and most 18Ws), and this is no exception. Always have a schematic handy, and always pay attention to it. It's more important than the layout, though the layout has important info as well.

Thanks,
Josh
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Re: Building Modern Ground Schemes (JMPGuitars_18_Watt)

Post by davemojo »

JMPGuitars wrote:
Sun 10/31/21 9:56 am
davemojo wrote:
Sun 10/31/21 8:55 am
I want to build now the exact project JMPGuitars_18_Watt layout.
Which one? Lite 2b(ish)? There's a lot of projects that start with that. ;)
1) Unless I am not aware but I don't think I can adapt a predrilled 18 watts chassis with the above project?
Most of the basic projects, including the Lite 2b(ish), will fit into a standard 18W chassis. Only my larger projects require a custom chassis. I do sell a custom chassis that accommodates the larger projects if you ever go that route, it's $150 for just the chassis, but international shipping won't be cheap. I do have custom faceplates for the Tremolo TMB to match the chassis, and I will eventually have other project versions available as well.
4) For the layout I have one silly question, but I am asking myself why was done this way, there seems to be two resistors with no written value but from the color band they seems 800k Ohms, see attached, is there a reason why those 2 are represented differently with no written value?

5) It is ok to build it and post step by step photos and you could check each step? I wouldn't do that if it was not the really first time doing so :-)
All of the layouts have an accompanying SCHEMATIC. The schematic has the values written clearly. Those plate resistors are almost always 100K in all of my projects (and most 18Ws), and this is no exception. Always have a schematic handy, and always pay attention to it. It's more important than the layout, though the layout has important info as well.

Thanks,
Josh
Thanks Josh I am referring indeed to :

18 Watt Lite 2b (ish)

1) see attached this is what i mean, so where is it the Schematics belonging to it I am missing its schematic.
2) So would this one fit the normal 18 Watts chassis? The one I used and built so far are including the tremolo but this one has no tremolo so the predrilled chassis would have the holes and the plates for the tremolo included. Would you point me to a link or something online that shows me the chassis needed to just have a clear picture of what i need , just to avoid confusion :-)

3) So on this layout the two resistor I meant are 100K???? Of course I don't have the schematic to compare can you point me out to its schematic?
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Re: Building Modern Ground Schemes (JMPGuitars_18_Watt)

Post by JMPGuitars »

davemojo wrote:
Sun 10/31/21 10:11 am
Thanks Josh I am referring indeed to :

18 Watt Lite 2b (ish)

1) see attached this is what i mean, so where is it the Schematics belonging to it I am missing its schematic.
2) So would this one fit the normal 18 Watts chassis? The one I used and built so far are including the tremolo but this one has no tremolo so the predrilled chassis would have the holes and the plates for the tremolo included. Would you point me to a link or something online that shows me the chassis needed to just have a clear picture of what i need , just to avoid confusion :-)

3) So on this layout the two resistor I meant are 100K???? Of course I don't have the schematic to compare can you point me out to its schematic?
All the docs are here: viewtopic.php?t=24431
Schematic: https://18watt.com/files/JMPGuitars_18_ ... ematic.pdf

Yes, it will fit a normal 18W chassis. The Lite 2b is essentially a modified 1st channel of the standard 18W.

Thanks,
Josh
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Re: Building Modern Ground Schemes (JMPGuitars_18_Watt)

Post by davemojo »

JMPGuitars wrote:
Sun 10/31/21 10:42 am
davemojo wrote:
Sun 10/31/21 10:11 am
Thanks Josh I am referring indeed to :

18 Watt Lite 2b (ish)

1) see attached this is what i mean, so where is it the Schematics belonging to it I am missing its schematic.
2) So would this one fit the normal 18 Watts chassis? The one I used and built so far are including the tremolo but this one has no tremolo so the predrilled chassis would have the holes and the plates for the tremolo included. Would you point me to a link or something online that shows me the chassis needed to just have a clear picture of what i need , just to avoid confusion :-)

3) So on this layout the two resistor I meant are 100K???? Of course I don't have the schematic to compare can you point me out to its schematic?
All the docs are here: viewtopic.php?t=24431
Schematic: https://18watt.com/files/JMPGuitars_18_ ... ematic.pdf

Yes, it will fit a normal 18W chassis. The Lite 2b is essentially a modified 1st channel of the standard 18W.

Thanks,
Josh
That's great thank you.
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Re: Building Modern Ground Schemes (JMPGuitars_18_Watt)

Post by davemojo »

Ok so all the above points are clear

Just one more point of discussion

for my understanding and this was confirmed by Josh but some other folks do not 100% fully agree. the topic is resistors

I learnt and read that carbon composite R are noisy maker they will produce all sort of crackling and frying. Opposite to Metal film are the only possible no noise option. I would say then the following:

Carbon film resistors are a good compromise between the low noise and excellent stability of metal film and the subjective "warmth" of carbon composition?

Would that be correct? I read a lot and it seems that this is accurately correct but I am still curios to hear other opinions?

I also know that larger wattage resistors are quieter than smaller ones, due to the geometry of the part itself.

In other words shall I build this 18 Watts from Josh schematic with metal film or carbon film is also OK?
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Re: Building Modern Ground Schemes (JMPGuitars_18_Watt)

Post by JMPGuitars »

davemojo wrote:
Sun 10/31/21 11:37 am
In other words shall I build this 18 Watts from Josh schematic with metal film or carbon film is also OK?
I used to build with carbon film for that reason. But that reason is magic mojo BS. I exclusively build with CMF metal film resistors, and my amps sound amazing, no lack of warmth at all. My opinion on it can be summed up by this: I have a lot of stock of carbon film resistors that I'll probably never use unless specifically requested. The CMF metal film resistors sound great, with very low noise.

If I use Carbon Comp, they're exclusively on the PI plates (as pictured in the layout you posted). There's supposedly a benefit to them being there, but that's also the only place they benefit.

All that said, carbon film are fine if that's what you want to use, but don't expect them to be magically better than anything.

Thanks,
Josh
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Re: Building Modern Ground Schemes (JMPGuitars_18_Watt)

Post by davemojo »

JMPGuitars wrote:
Sun 10/31/21 11:44 am
davemojo wrote:
Sun 10/31/21 11:37 am
In other words shall I build this 18 Watts from Josh schematic with metal film or carbon film is also OK?
I used to build with carbon film for that reason. But that reason is magic mojo BS. I exclusively build with CMF metal film resistors, and my amps sound amazing, no lack of warmth at all. My opinion on it can be summed up by this: I have a lot of stock of carbon film resistors that I'll probably never use unless specifically requested. The CMF metal film resistors sound great, with very low noise.

If I use Carbon Comp, they're exclusively on the PI plates (as pictured in the layout you posted). There's supposedly a benefit to them being there, but that's also the only place they benefit.

All that said, carbon film are fine if that's what you want to use, but don't expect them to be magically better than anything.

Thanks,
Josh
Gotcha ya perfectly understood.

Thanks
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Re: Building Modern Ground Schemes (JMPGuitars_18_Watt)

Post by Bieworm »

JMPGuitars wrote:
Sun 10/31/21 11:44 am
davemojo wrote:
Sun 10/31/21 11:37 am
In other words shall I build this 18 Watts from Josh schematic with metal film or carbon film is also OK?
I used to build with carbon film for that reason. But that reason is magic mojo BS. I exclusively build with CMF metal film resistors, and my amps sound amazing, no lack of warmth at all. My opinion on it can be summed up by this: I have a lot of stock of carbon film resistors that I'll probably never use unless specifically requested. The CMF metal film resistors sound great, with very low noise.

If I use Carbon Comp, they're exclusively on the PI plates (as pictured in the layout you posted). There's supposedly a benefit to them being there, but that's also the only place they benefit.

All that said, carbon film are fine if that's what you want to use, but don't expect them to be magically better than anything.

Thanks,
Josh
Because you're my mentor, and you've always proven yourself to be right in situations I thought otherwise.. I always use MF resistors trough-out.. except maybe the PI plates. I find all of my amps really warm and articulate.. and silent noisewise.
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Re: Building Modern Ground Schemes (JMPGuitars_18_Watt)

Post by JMPGuitars »

Bieworm wrote:
Sun 10/31/21 12:50 pm
I always use MF resistors trough-out.. except maybe the PI plates. I find all of my amps really warm and articulate.. and silent noisewise.
I know you use different types of MF, which is fine. I dunno if the CMF are better than any others in reality or not, but I love that the values are generally printed clearly on them. That's honestly my favorite part about them (besides them performing well of course). 😂
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Re: Building Modern Ground Schemes (JMPGuitars_18_Watt)

Post by Bieworm »

JMPGuitars wrote:
Sun 10/31/21 1:31 pm
Bieworm wrote:
Sun 10/31/21 12:50 pm
I always use MF resistors trough-out.. except maybe the PI plates. I find all of my amps really warm and articulate.. and silent noisewise.
I know you use different types of MF, which is fine. I dunno if the CMF are better than any others in reality or not, but I love that the values are generally printed clearly on them. That's honestly my favorite part about them (besides them performing well of course). 😂
I know, but the dale MF are only 0.4W. I use 1W and 2W all over. That's my ignorance to safeguard all I solder... Maybe some day I know enough to use the right ones at the right spots.. but for now, 1W and 2W all over, except the B+ line and power amp.. that's at least 5 or 10W 😉
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Re: Building Modern Ground Schemes (JMPGuitars_18_Watt)

Post by JMPGuitars »

Bieworm wrote:
Sun 10/31/21 2:05 pm
I know, but the dale MF are only 0.4W. I use 1W and 2W all over. That's my ignorance to safeguard all I solder... Maybe some day I know enough to use the right ones at the right spots.. but for now, 1W and 2W all over, except the B+ line and power amp.. that's at least 5 or 10W 😉
The CMF series I get are all 1W, 500V. The only one that isn't is the 2.2M .5W, 250V in the tremolo. Those are available in 1W, but they haven't been in stock, and it doesn't matter for that location. I usually get 1% or better.
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Re: Building Modern Ground Schemes (JMPGuitars_18_Watt)

Post by davemojo »

Hey Josh

You mentioned:
Most of the basic projects, including the Lite 2b(ish) will fir an 18 Watt chassis
Is that meant as a basic chassis not predrilled?

https://www.tube-town.net/ttstore/tt-ch ... -x-65.html

Because the predrilled will have extra holes that are not needed for the Lite 2b(ish)

https://www.tube-town.net/ttstore/tt-ch ... 8watt.html
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Re: Building Modern Ground Schemes (JMPGuitars_18_Watt)

Post by JMPGuitars »

davemojo wrote:
Mon 11/01/21 9:26 am
Hey Josh

You mentioned:
Most of the basic projects, including the Lite 2b(ish) will fir an 18 Watt chassis
Is that meant as a basic chassis not predrilled?

https://www.tube-town.net/ttstore/tt-ch ... -x-65.html

Because the predrilled will have extra holes that are not needed for the Lite 2b(ish)

https://www.tube-town.net/ttstore/tt-ch ... 8watt.html
Extra holes don't matter. You can get covers or plugs for the tube socket holes if that bothers you. You would want a custom faceplate anyway, which would cover all the extra pot holes.

Or you can put in the time and effort and money for tools to drill the chassis out yourself, but that's a lot more work and money than it's worth, unless that's something you want to do again in the future, for a lot of amps. But from your previous comments, I don't think that's the case? Let me put it this way- I have the tools and such to do this, and I still don't like doing it. That's why I designed a proper chassis and paid a company do it with laser cutting.
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Re: Building Modern Ground Schemes (JMPGuitars_18_Watt)

Post by davemojo »

JMPGuitars wrote:
Mon 11/01/21 10:23 am
davemojo wrote:
Mon 11/01/21 9:26 am
Hey Josh

You mentioned:
Most of the basic projects, including the Lite 2b(ish) will fir an 18 Watt chassis
Is that meant as a basic chassis not predrilled?

https://www.tube-town.net/ttstore/tt-ch ... -x-65.html

Because the predrilled will have extra holes that are not needed for the Lite 2b(ish)

https://www.tube-town.net/ttstore/tt-ch ... 8watt.html
Extra holes don't matter. You can get covers or plugs for the tube socket holes if that bothers you. You would want a custom faceplate anyway, which would cover all the extra pot holes.

Or you can put in the time and effort and money for tools to drill the chassis out yourself, but that's a lot more work and money than it's worth, unless that's something you want to do again in the future, for a lot of amps. But from your previous comments, I don't think that's the case? Let me put it this way- I have the tools and such to do this, and I still don't like doing it. That's why I designed a proper chassis and paid a company do it with laser cutting.
Thanks feel exactly the same. I have some plans to actually build amps, however I wouldn't be the main guy doing that, I have someone that has more expertise in the electronics part, and eventually I would be his support, my role instead would be more into the Cabinet Combo Head shell creation since apparently I am handy on this.

Since I have created a small business only for guitar cabinets that seems to be working fine.

This was my latest creation we made 10 of them for a rock band here in the Netherlands
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Re: Building Modern Ground Schemes (JMPGuitars_18_Watt)

Post by Bieworm »

I like building cabs too.. but I use medium piping, I think it's more elegant..
20211023_235059.jpg
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