Planning my first build

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djpj1977
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Planning my first build

Post by djpj1977 »

Hey all, I signed up here last week because I want to build my own amp and I think an 18 watt TMB should be cool for a first build. I'm new to amp building but I've put 10 pedal kits together and mostly all worked with no troubleshooting. I've swapped tubes and done biasing in my amps, done some electrical troubleshooting on my vehicles and other equipment, and took a lower division electromagnetism class in a calculus level physics series. I'm interested in learning the inner workings of tube amps and feel competent enough to complete a build with guidance.

So I've been looking at the 18 watt kits out there and I'm leaning towards the Mojotone TMB because it has a JCM 800 style preamp and I'll be playing a mix of classic rock, hard rock, and metal. Before I pull the trigger I'm hoping you guys can help me out with a few questions.

I notice that most kits don't list all the brands of parts included. Is anyone familiar with the MT kit? Are there any components I should consider upgrading? I don't mind spending more to get the best sound and dependability.

Without getting too complicated, are there any design upgrades I should make right out of the gate? One thing I've noticed looking at the layout- (https://www.mojotone.com/kits/BritishAm ... lifier-Kit) It looks to me like the master volume feeds the input of the PI from what I've read it's far better after.

I've read a few people complaining about mistakes in the MT build docs (mainly leaving out shielded wires iirc). All of these 18 watters are based on the same circuit right? Could I use a different source for build docs? I heard one company gives 50+ pages instructions with some theory. Can't remember who, but I'll find it. Like I said, I want to learn what's going on.

As far as mods, is it worth doing these? Like I said, I'm not that familiar with these amps so maybe some of these don't even make sense to do. I'm assuming it would be best to do any mods after the build is tested and complete to make any troubleshooting easier (unless there's too much disassembly involved). Here's what I would like to have someday:
FX loop
Footswitchable channels
Switchable to solid state rectifier
Variable voltage
Onboard reverb (I may build a 'rack' unit that the head can sit on since I don't have any other rack equipment or my musikding 3verb has a good sound for digital).

Finally, I'm getting ahead of myself here, feel free to ignore. How hard would it be to add a super clean preamp channel (fender comes to mind). Initially I was thinking of just building a second amp for cleans and A/B switch them, but was curious how much of a PITA combining the circuits would be.

Thanks for any input.
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Re: Planning my first build

Post by JMPGuitars »

Welcome to the site!

Regarding the mojotone kit:

NO! Run away!

Seriously, it's the worst kit available. There are significantly better docs available in our downloads section here, which you can source the parts yourself for.

If you prefer a kit, you should look at GDSamps.com, Trinity, or Ceriatone.

I like a lot of mojotone's stuff, and their cabinets are great. But their kit design is utter garbage. Save yourself the headache, and look at others.

Do yourself another huge favor and look at the soldering and grounding schemes in my signature.

Thanks,
Josh
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Re: Planning my first build

Post by djpj1977 »

Thanks for the response Josh. I've read through some of your threads and I've got to say, your builds look and sound great! I respect what you do so I'm definitely planning to look closer at your links. Do you have a specific recommendation for a high gain 18 watt? I play a range of music, from old school Metallica, Ozzy, Pantera, AC/DC Red Hot Chili Peppers, to Led Zeppelin for example. I've even tackled a couple classical pieces. I like the idea of having extra gain on tap for my first build, that's why I was leaning towards Mojo's jcm 800 style preamp.

I thought of sourcing my own parts if I can find the right design, but it seemed overwhelming being my first build. If I can find build docs, a parts list, and some discussion walking me through best parts selection, I may go that route. But I want to get started and that prep work is going to take time...
Thanks,
Dean
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Re: Planning my first build

Post by JMPGuitars »

djpj1977 wrote:
Sat 03/27/21 2:50 pm
Thanks for the response Josh. I've read through some of your threads and I've got to say, your builds look and sound great! I respect what you do so I'm definitely planning to look closer at your links. Do you have a specific recommendation for a high gain 18 watt? I play a range of music, from old school Metallica, Ozzy, Pantera, AC/DC Red Hot Chili Peppers, to Led Zeppelin for example. I've even tackled a couple classical pieces. I like the idea of having extra gain on tap for my first build, that's why I was leaning towards Mojo's jcm 800 style preamp.

I thought of sourcing my own parts if I can find the right design, but it seemed overwhelming being my first build. If I can find build docs, a parts list, and some discussion walking me through best parts selection, I may go that route. But I want to get started and that prep work is going to take time...
Thanks,
Dean
Thank you.

Don't be afraid, and don't be in a rush. Yes, you will enjoy playing this amp for years and years...but for now, enjoy the process of building it.

For your first build, I would say a Superlite TMB is the best option. It's simpler than a lot of builds, and it has a cascaded preamp so you get some extra gain from it. It's pretty tasty- an overall great sounding amp.


The best circuit for what you described would be one I haven't released yet, but shouldn't be your first build anyway. It's called the "TMB Xtra" - which has a switchable preamp between cascade or parallel, and can go from moderate to high gain (and obviously has a TMB tone stack). I will be releasing a PCB version of this eventually. If you want a simpler version that would be better as a 1st build, take a look at my "EF86 Xtra" circuit in the downloads section. That can get pretty mean.

I like Heyboer or Mercury Magnetics transformers. I think the GDS version of the Heyboers are best because they have solder tabs on the PT instead of leads. PTs with leads are annoying, because you might want to make a change and then be forced to splice a wire. With the solder tabs you can just replace the whole wire.

For general resistors, I like CMF 1Watt metal film. I typically use series 150 or Mallory 150 capacitors. I'm sure other people would have some opinions on parts too. Whatever you do, don't get caught in magic mojo B.S. Good parts are good parts.

One note though, if you don't have an oscilloscope, SoZo is the best brand for capacitors because they mark the outside foils, and nobody else does anymore. If you do have a scope, then you can find the outer foils yourself.

Thanks,
Josh
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Re: Planning my first build

Post by djpj1977 »

JMPGuitars wrote:
Sat 03/27/21 3:19 pm
Thank you.

Don't be afraid, and don't be in a rush. Yes, you will enjoy playing this amp for years and years...but for now, enjoy the process of building it.

For your first build, I would say a Superlite TMB is the best option. It's simpler than a lot of builds, and it has a cascaded preamp so you get some extra gain from it. It's pretty tasty- an overall great sounding amp.


The best circuit for what you described would be one I haven't released yet, but shouldn't be your first build anyway. It's called the "TMB Xtra" - which has a switchable preamp between cascade or parallel, and can go from moderate to high gain (and obviously has a TMB tone stack). I will be releasing a PCB version of this eventually. If you want a simpler version that would be better as a 1st build, take a look at my "EF86 Xtra" circuit in the downloads section. That can get pretty mean.

I like Heyboer or Mercury Magnetics transformers. I think the GDS version of the Heyboers are best because they have solder tabs on the PT instead of leads. PTs with leads are annoying, because you might want to make a change and then be forced to splice a wire. With the solder tabs you can just replace the whole wire.

For general resistors, I like CMF 1Watt metal film. I typically use series 150 or Mallory 150 capacitors. I'm sure other people would have some opinions on parts too. Whatever you do, don't get caught in magic mojo B.S. Good parts are good parts.

One note though, if you don't have an oscilloscope, SoZo is the best brand for capacitors because they mark the outside foils, and nobody else does anymore. If you do have a scope, then you can find the outer foils yourself.

Thanks,
Josh
Cool, thanks for the info. I'll check your suggestions out. Do you know if Graydon from GDS is here? I tried going to his site, but it looks like there's a redirect hack so I end up at some shady pharmacy site. Turns out we're both in Michigan so I'm interested in seeing what he has.
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Re: Planning my first build

Post by JMPGuitars »

djpj1977 wrote:
Sat 03/27/21 3:40 pm
Cool, thanks for the info. I'll check your suggestions out. Do you know if Graydon from GDS is here? I tried going to his site, but it looks like there's a redirect hack so I end up at some shady pharmacy site. Turns out we're both in Michigan so I'm interested in seeing what he has.
Are you sure you went to the right site? I just checked and didn't get redirected anywhere. Here's a direct link: http://gdsamps.com/parts/ If you click order now it brings you to paypal, so you should be secure.

Graydon was one of the founding member of this site, but he hasn't been active in years. You can email him directly to see about picking stuff up: http://gdsamps.com/contact/

Thanks,
Josh
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Re: Planning my first build

Post by Bieworm »

Forget super clean on an 18 watt. To get the grind you're looking for you'd have to crank the amp.. that means power tube overdrive. Clean was waaayyyy before that 😉
I built a dual channel amp that started out as a tone king imperial clone. After months and months of troubleshooting and tweaking I ended up with another PI, tweaked the clean channel until it finally had mids and gutted the entire OD channel to resemble a marshall type circuit. The tone king OD circuit was absolutely unuseable. Now it's really nice, that amp.. but it took eons to get there...but it still ain't a marshall though. So I think I know what you're after... I don't think those 2 circuits (marshall+fender) will blend in 1 amp. It's the holy grail everybody's after... no one succeeded so far, although some claim they did...
I've come to realize that I don't need the fender clean anymore.. since I play 18 watts that's all I need. So, like Josh said... build a simple amp to start with. If the building bug bites you, you're going to build more amps after that. And by then you understand them more and more. You'd be surprised how much gain you can get from a simple 18 watt superlite TMB when cranked!!! And for earlier OD you can boost it with a pedal...
Enjoy the trip and be careful. Welcome to the site!!!
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Re: Planning my first build

Post by djpj1977 »

JMPGuitars wrote:
Sat 03/27/21 4:09 pm
djpj1977 wrote:
Sat 03/27/21 3:40 pm
Cool, thanks for the info. I'll check your suggestions out. Do you know if Graydon from GDS is here? I tried going to his site, but it looks like there's a redirect hack so I end up at some shady pharmacy site. Turns out we're both in Michigan so I'm interested in seeing what he has.
Are you sure you went to the right site? I just checked and didn't get redirected anywhere. Here's a direct link: http://gdsamps.com/parts/ If you click order now it brings you to paypal, so you should be secure.

Graydon was one of the founding member of this site, but he hasn't been active in years. You can email him directly to see about picking stuff up: http://gdsamps.com/contact/

Thanks,
Josh
Yes, I'm sure. Looks like it's only a problem while clicking on a google search links. Your links and other search engines get me there no problem.
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djpj1977
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Re: Planning my first build

Post by djpj1977 »

Bieworm wrote:
Sat 03/27/21 4:24 pm
Forget super clean on an 18 watt. To get the grind you're looking for you'd have to crank the amp.. that means power tube overdrive. Clean was waaayyyy before that 😉
I built a dual channel amp that started out as a tone king imperial clone. After months and months of troubleshooting and tweaking I ended up with another PI, tweaked the clean channel until it finally had mids and gutted the entire OD channel to resemble a marshall type circuit. The tone king OD circuit was absolutely unuseable. Now it's really nice, that amp.. but it took eons to get there...but it still ain't a marshall though. So I think I know what you're after... I don't think those 2 circuits (marshall+fender) will blend in 1 amp. It's the holy grail everybody's after... no one succeeded so far, although some claim they did...
I've come to realize that I don't need the fender clean anymore.. since I play 18 watts that's all I need. So, like Josh said... build a simple amp to start with. If the building bug bites you, you're going to build more amps after that. And by then you understand them more and more. You'd be surprised how much gain you can get from a simple 18 watt superlite TMB when cranked!!! And for earlier OD you can boost it with a pedal...
Enjoy the trip and be careful. Welcome to the site!!!
That makes total sense. Since the tone I'm looking for from an 18 watt amp requires power tube distortion the amp can't share the power stage with a clean channel. At least not without adjusting levels every time you switch channels. So I'll take your advice and start with a simple 18 watt build. Maybe just rolling back the volume on my guitar will clean it up enough for my taste. If not, I'll build a fender style amp.
Thanks Bieworm, glad I found you guys!
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Re: Planning my first build

Post by Bieworm »

Smart to start simple.
I'm building my 6th amp right now.. a 36W tremolo TMB reverb with 6L6 power tubes. .
It's my 3rd tremolo TMB 😃😃😃 ...It's the best amp ever..to my taste at least.. if you like Jimi and Page... that's the sound I hear
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Re: Planning my first build

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djpj1977 wrote:
Sat 03/27/21 4:37 pm
Yes, I'm sure. Looks like it's only a problem while clicking on a google search links. Your links and other search engines get me there no problem.
Oh, then it sounds like Google has some bad links to his site. That happens unfortunately. Stupid Google. 🙄

If you're building the Superlite TMB, make sure you use the latest docs I posted. Those are the best version. viewtopic.php?f=25&t=24430
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Re: Planning my first build

Post by zaphod_phil »

Bieworm wrote:
Sat 03/27/21 5:26 pm
Smart to start simple.
I'm building my 6th amp right now.. a 36W tremolo TMB reverb with 6L6 power tubes. .
Why did you chose 6L6 tubes? 8O
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Re: Planning my first build

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zaphod_phil wrote:
Thu 04/01/21 4:12 pm
Bieworm wrote:
Sat 03/27/21 5:26 pm
Smart to start simple.
I'm building my 6th amp right now.. a 36W tremolo TMB reverb with 6L6 power tubes. .
Why did you chose 6L6 tubes? 8O
Merely out of curiosity. I will be trying el34 too
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Re: Planning my first build

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Bieworm wrote:
Thu 04/01/21 9:46 pm
Merely out of curiosity. I will be trying el34 too
6L6 and EL34 need output transformers with different primaries. It's not really possible to compare the two types unless the transformers are changed with them.

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Re: Planning my first build

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TriodeLuvr wrote:
Thu 04/01/21 10:10 pm
Bieworm wrote:
Thu 04/01/21 9:46 pm
Merely out of curiosity. I will be trying el34 too
6L6 and EL34 need output transformers with different primaries. It's not really possible to compare the two types unless the transformers are changed with them.

Jack
is that so? If I look for output transformers there is always the tube type specified in the datasheets. It always says both 6L6 an EL34.
I have a 36W OT with 4k prim...
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Re: Planning my first build

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Bieworm wrote:
Fri 04/02/21 1:11 am
TriodeLuvr wrote:
Thu 04/01/21 10:10 pm
Bieworm wrote:
Thu 04/01/21 9:46 pm
Merely out of curiosity. I will be trying el34 too
6L6 and EL34 need output transformers with different primaries. It's not really possible to compare the two types unless the transformers are changed with them.

Jack
is that so? If I look for output transformers there is always the tube type specified in the datasheets. It always says both 6L6 an EL34.
I have a 36W OT with 4k prim...
The 4K primary (sometimes 3.5K or 3.8K) is suitable for a pair of EL34s. 6L6 variants perform best with a higher impedance primary, typically 6.6K.

The chart below is from the 6L6WGB datasheet. The loss in output power when the two tubes drive a lower Z transformer is typical of all the 6L6 series. Whose datasheets are you reading that don't make this distinction?

Image
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Re: Planning my first build

Post by Bieworm »

I was referring to the datasheets of OT's with 4k prim. I'm not worried about the loss in power because it will still be plenty powerful. And like I aready stated, the 6L6 adventure is merely out of curiosity.. ofcourse there will be put in EL34 tubes eventually ;)
but who knows I might like the 6L6 's so much I won't even bother to go the EL34 route :D :D :D
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Re: Planning my first build

Post by JMPGuitars »

TriodeLuvr wrote:
Thu 04/01/21 10:10 pm
Bieworm wrote:
Thu 04/01/21 9:46 pm
Merely out of curiosity. I will be trying el34 too
6L6 and EL34 need output transformers with different primaries. It's not really possible to compare the two types unless the transformers are changed with them.

Jack
That's not accurate. As your other post shows, the output level changes with 6L6, but that doesn't matter unless you're trying to target a specific wattage. With a 4K primary, he can hit the 36W to 40W range with either tube set pretty easily.
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Re: Planning my first build

Post by Bieworm »

I'm not out on a specific wattage. I'm only wondering how the extremely sublime preamp of the tremolo TMB combines with the 6L6 power after it. Josh has the EL34 area covered...I think this design deserves the research and expansion. 6L6 tubes tend to beef things up in their own way, different from an EL34. I know it robs some marhalliness in the end, but that isn't per se a bad thing. And I'm convinced Josh is going to look at the new born tremolo TMB with parentlike pride😄
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Re: Planning my first build

Post by TriodeLuvr »

What can I say? You can use any tube with any transformer if performance isn’t important. Operating 6L6s in AB1 with a 4K load is inefficient, and the power lost in the mismatch is dissipated by the anodes. This means the tubes run hotter for a given output, and their tone will be different as well. Can you compare the sound of a properly terminated pair of EL34s to improperly terminated 6L6s? Of course, but that’s not what I think of when someone says they’ll compare two tube types. It’s like comparing a 4 ohm speaker to a 16 ohm speaker without changing the transformer taps. Josh, extracting more power from a pair of 6L6s mismatched with a 4K transformer is only “easy” if higher B+ voltages are available and higher anode dissipation can be tolerated. Let’s be clear - I’m not attempting to tell anyone what they can or can’t, or should or shouldn’t do in this matter. I’m only pointing out the facts of operation as they pertain to these two tube types.

Jack
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