After tweaking the basic Ceriatone 18W TMB circuit I have finally achieved near perfection in sound.  Having built four amps in the past two years this amp gets it right sound wise.   Plexi sound at ear friendly volume.  A pleasure to play!

Enclosed is a schematic to share.  OT subbed with a Mercury full stack which gets better bass extension without a lot of fartiness.   Highs are smooth and not harsh.  Finally solved a too much gain issue in the TMB channel by substituting a 12AU7 in the tone stack driver (V3 cathode follower).   The uF signal caps were swapped with Sozo vintage and the plate resistors NOS Piher carbon film.  Line level FX loop allows the use of time domain effects (G Force in my case).  The rest is all Ceriatone and Nik's wonderful interpretation.  It sounds great!

Guitar Amp Schematic Microsoft Cloud Drive... Click below in a browser, choose "Ceriatone 18W TMB" directory, and download .pdf files.   "18Watt_TMB_Custom_A6.0.pdf" has all the changes made. 

https://onedrive.live.com/?id=636DC4E8060D66A1%21338&cid=636DC4E8060D66A1

I wired the lamp to the transformer as that was the closest place to do so.

Contact Nik about the transformer Earth gnd.  I believe my year old transformer had a wire or a connector lug for this.   

I've had good luck with PPIMV on my amps.  They sound best on the upper half of the control.  So everything is a trade off.   They are cheap and easy to install especially on the 18W amps.  Take a look in the mods section on the Ceriatone web site.  The 1M ohm pot across the power tube grids is all it takes for these amps.   If it doesn't work out two snips of a wire cutter and you are back to normal.  Scott

I have done it no problem!    You can certainly do so without damage to the amp.  Give it a try.  Scott

Without the 100 ohm resistor dialing the tone control all the way counterclockwise would shunt all the signal from this channel to directly to ground.   And you would get little or no output.  Addition of the resistor is meant to be a lower limit stop and prevent totally killing the channel when adjusting tone on the low end. 

Here's a schematic.pdf of the latest Ceriatone 18W TMB Layout 23.  The wire colors, component values, layout markers, and design are faithfully reproduced for this schematic.   The schematic is meant to be an aid for assembly and debug.

Guitar Amp Schematic Microsoft Cloud Drive... Click below in a browser, choose "Ceriatone 18W TMB" directory, and download .pdf files.  

https://onedrive.live.com/?id=636DC4E8060D66A1%21338&cid=636DC4E8060D66A1

You got the right idea.  The JTM45 was modeled after the '59 Bassman so connect the right speaker and play away!  Scott

I just recently built a Ceriatone 18W TMB and briefly had the TMB master volume control installed instead of the PPIMV.  I could not run the TMB preamp volume and TMB master volume above, like you say 9 o'clock, without a lot of distortion.  The problem is the TMB channel has two gain stages while the normal channel one.   So on my 18W TMB I took out the TMB master volume and made the control on the front faceplate a PPIMV (which I dearly love!).   To balance the normal and TMB channel I simply attenuated the tone stack output with a resistor divider feeding the PI.  I used a 7.5 to 1 attenuation which gives the TMB channel slightly more gain that the normal but not much.  I now have a lot of range on the TMB volume control plus before the TMB had a lot of noise   I can also jump channels with ease.

Anyway here is a schematic of my 18W TMB.   Take a look at the treble pot wiper.  There are two resistors: 649K and 10oK ohm to ground.  This is a voltage divider that is attenuating the TMB channel before it hits the PI.   

Scott

I just built a Ceriatone 18W TMB and wired the PPIMV control as shown in the Mods section on the main Ceriatone web site.  The PPIMV sounds great and get a great cranked tone at moderate levels. 

I did have to modify the TMB channel as there is an extra gain stage (cathode follower) to drive the tone stack.  So without the normal TMB channel master volume (PPIMV instead) there is way too much gain in the TMB channel.  I used a 7.5 to 1 resistor divider between the treble pot wiper and the PI coupling cap to bring the TMB gain down.  Now the TMB channel is more balanced and only slightly hotter than the normal channel.  Sounds great!   I have a hotplate but don't need it with this amp and the PPIMV.

Scott

Touche'.  Yes I mean (and you mean I'm sure) EL 34s.

Has any tried KT77s in place of the EL34s in a Ceriatone Plexi 50?  I think I understand the tonal differences but would appreciate your opinion.  Maybe a little more headroom before breakup and perhaps a little more rounded overdrive sound.   What about midrange drive, bass response, and treble clarity/harshness?

If you have sub them are the KT77s easy to setup as the EL84s?   Thinking if I don't like them I can always go back to EL84s.  Thanks, Scott

I just saw on the main Certiatone.com web site. 

"18 Watt, 18 W TMB & 18 W TMB EF86 Sale from 5 Nov 09 to 1 Jan 2010! 10% Off Across Board"

I received an Email from Nik with the dimensions.  The 18 watter heads will fit a small box.

{Nik} The chassis is 20 x 6.75 x 2.5", 21.5" with flanges.  This should fit small box, which is 26" long.  The cutout for the front is same at 16.5" but the back, youd need about 18" or so.

I also looked at some early posts and got some sources for boxes such as Gabkits, VintageHeadBox, Mojotone, and Ebay seller sourmashguitars I think.  Scott

P.S.  Nik sent me another Email to emphasize that the back needs an 18" cutout for the Ceriatone 18 watt.

P.S.S.  I went ahead and bought a Ceriatone head box.  It was only about $216.00 add on including shipping with the rest of my 18 watt TMB order.  No holes to drill, logo plate, and perfect fit.

Does the 18 Watt TMB chassis fit in a small Marshall style head box?  Are there any mechanical dimensions available on the Ceriatone web pages?  Does anyone know the width of the chassis?  Any help is appreciated.  Thanks, Scott