Which kit for me, a newbie?

[jchrisf]

Hi the kits from ampmaker are excellent with very good quality transformers. Ampmaker also give step by step instructions photos schematics layouts. Approx 30 pages! Down load able. You might find that helpful on your first build. Modulus amps also do very good quality kits but you will only get a schematic and a layout ( both companies UK based)

Best of luck

Thanks.. unfortunately they are not shipping to the US right now.. but by the time I make up my mind they might be.

[jchrisf]

I don't think you can go too wrong with any of the kits from Trinity. From what I can tell the 6V6 plexi models may be dual EL84/6V6 types? I think a lot of mojo in the 18W type amp comes from the EL84 so that is my general preference. The addition of 2 extra power tubes with a switch to rebias is nice in that you will have the noval and octal sockets ready to go but keep in mind an additional level of complexity for a first build.

The PLEXI tag is thrown around quite a bit with the 18W kits but take note that the traditional plexi circuit has solid state rectification, negative feedback and fixed bias on the power tubes, so all attempts to reproduce the true plexi vibe on a traditional 18W platform will fall a bit short in terms of expectation. Also keep in mind that some of the killer mojo in a traditional plexi comes from blending the 2 input channels using a jumper.

In my case I built the Trinity 18W plexi kit but at the end of the day I ended up modding the PI and post PI bypass caps to match the values of the classic 18W. To me it just sounds better that way. Again really easy to do, you just need some additonal resistors and caps on hand.

The 18W plexi that you linked is very nice sounding but definitely not the sound of a classic 18W. There are some VH tones in there. .. and beyond. He has a a second video with that amp that is more impressive. From what I can tell, that kit is from TubeTown (German) and it is the PX18 model. I had a look at the schematic and it is basically a plexi preamp mated to an 18W EL84 power section. It has solid state rectification, a presence control (negative feedback) and fixed bias on the power tubes so they are definitely trying to capture the classic "plexi" vibe here. A very different beast than the classic 18W. However, what you are hearing in the videos is clearly not a classic plexi sound ... way more distortion on tap. He mentioned Jose/Friedman mods so that will almost certainy involve 3 preamp gain stages plus CF with some hotrodding or the use of diodes to obtain some additional clipping (which is one of the Jose mods used on plexis where the original integrity of the amp needed to be maintained). It sounds to me even hotter than the Friedman PT-20. So my guess it that the kit has been modded to some degree. If you are into the 80s metal kind of sound then that particular chasis may be better suited to future modding since the layout of pots and inputs would be better aligned to introducing a new turret/tag board than the typical 18W TMB type chasis (just an opinion).

Anyway, interesting stuff but I will end it here since we are sliding away from a discussion on classic 18W circuits ......

Good to know. I'm amazed the knowledge you and others posting here have. Having a Plexi, JCM 800 and hot rodded (Jose Modded) version of both is my goal in the end. Those hot rodded tones are what I am going for but I also want the classic tone too. I'll have to consider TubeTown if their chassis are better suited.

[jchrisf]

Hi the kits from ampmaker are excellent with very good quality transformers. Ampmaker also give step by step instructions photos schematics layouts. Approx 30 pages! Down load able. You might find that helpful on your first build. Modulus amps also do very good quality kits but you will only get a schematic and a layout ( both companies UK based)

Best of luck

Never heard of Modulus before.. good to know. Their prices are nice but I wonder what shipping to the US would be? I wouldn't try one of these without the instructions until I knew what I was doing either through more research or building a kit with detailed instructions.

[jchrisf]

Some good perspective here. Whatever route you decide to take, I'd would highly advise avoiding Mojo. If you do a bit of searching you will find a recent slew of guys coming here after completing Mojo TMB 18W builds with oscillation and other problems. Their layouts are terrible and sometimes their layouts conflict with their schematics, causing further confusion for the inexperienced. Parts are selected for economy (making them money), not necessarily the best part for each location. In my opinion and experience, you would be far better off with a GDS or Trinity, if you must go with a kit, or simply take some time, review and compare schematics and layouts on this site (as well as Trinity's Plexi 18 build) and buy your own parts. You will gain a lot more experience and confidence in the process before you ever heat up your soldering iron. Soldering by numbers doesn't get you anything, and you will have no knowledge to troubleshoot if you make a mistake.

What matters most is the quality of the transformers. Don't be tempted to skimp there. GDS uses high quality Heyboer transformers wound to the proper specification. Trinity also uses Heyboer wound their own specification. You can buy an 18W head or combo chassis at Valvestorm or Modulus.

I didn't realize the transformers were the key to a great kit. I'll keep that in mind. Yeah, I might do Valvestorm or Modulus after I feel confident to fly on my own.

[crgfrench]

Keep in mind, some chassis are designed for a particular transformer footprint. e.g. my current build is in a Ceriatone chassis but I used GDS trannies and needed to do some chassis modification to make it work. Also, chassis selection will depend on whether you want to build a head or a combo, and where you want the controls to be (top or front) if it's a combo.

adapter.png

[JMPGuitars]

Keep in mind, some chassis are designed for a particular transformer footprint. e.g. my current build is in a Ceriatone chassis but I used GDS trannies and needed to do some chassis modification to make it work. Also, chassis selection will depend on whether you want to build a head or a combo, and where you want the controls to be (top or front) if it's a combo.
adapter.png

You should make more of those and sell them. They could work well to adapt as you have, or also to reinforce thinner chassis. .09 wouldn't need it, but some .06 could certainly use reinforcement.

[crgfrench]

I was thinking of asking Nik at Ceriatone and Graydon at GDS if they might want some to offer their clients. It's a nice combo but it also requires slightly drilling the 4 corners of the PT cutout in the chassis too, so it's not a perfectly simple drop-in...

Also if anyone cares, this setup fits perfectly in a Weber M18 1x12 cabinet.

[JMPGuitars]

I was thinking of asking Nik at Ceriatone and Graydon at GDS if they might want some to offer their clients. It's a nice combo but it also requires slightly drilling the 4 corners of the PT cutout in the chassis too, so it's not a perfectly simple drop-in...

Also if anyone cares, this setup fits perfectly in a Weber M18 1x12 cabinet.

You could always make them to order and list a few things in the marketplace here: viewforum.php?f=24

[dr redplate]

Hi my advice would be to select a 18watt kit with a proven track record and the best documentation you can get. Then build the kit vanilla flavour and get it working properly. Then you could introduce mods to make it sound like a "bigger" vintage Marshall.
To get your more hot rod sounds use it as a pedal platform. I would use a graphic eq pedal with clean boost to push the front end into distortion. You can set the tonal response using the eq to get a more more appropriate response for higher gain applications.
You would need to include a post PI master volume to give you some gain stage control. EL 84 valves are easily pushed beyond saturation into grid blocking distortion and I would recommend the ability to dial this back.
Modulus 18watt kits use a dagnall mains trx and and a replica RS output transformer.
Ampmaker get transformers made by relatively small suppliers and choose the ones to supply based on listening tests.
Get an appropriate speaker as well. since I live in the UK i use celestions. A 12inch green back or a g12H work well. Try and avoid using a speaker with a huge power handling rating. 30 watts is about right
I have only used kits from Modulus and Ampmaker so can only comment on these

To get a true "Plexi" experience you need to stand in front of 8 G12H speakers driven by four EL34 valves at full throttle! an experience to be remembered

[Bieworm]

I think Josh 's TMB tremolo gets pretty close to plexi territory. The hendrix vibe is definitely there...
https://www.dropbox.com/s/k4rlwdg0c64a9 ... 2.m4a?dl=0
Judge it for yourself...
The guitar is a jazzmaster . A les Paul is pure grind

[crgfrench]

Judge it for yourself...

Nice playing! What mic & interface did you record that with?

[Bieworm]

Judge it for yourself...

Nice playing! What mic & interface did you record that with?

Lol!!! A samsung s10 smartphone 's voice recorder