CONVERTING: MESA BOOGIE 50 Caliber+ to DUMBLE

[ngw]

Hi all,
Last year I posted about finding a PCB/Cct board for a Mesa/Boogie 50 Caliber+.
https://tubeamparchive.com/viewtopic.php?f=6&t=33523
I had no luck finding anything and was going to build the owner a new replica amp on eyelet board, but he said he would wait until he decided on what he wanted to do with it. He has other amps to use.

Since then I have built him one of my amps which is similar to a Dumble topography, ie: Clean preamp cascading into the OD stages, but not Dumble circuit values.
This amp has a 3 stage Clean with good headroom and an OD that goes from semi-Clean to high-gain Distortion, with a few switchable Tonal variations.
It has a foot-switchable parallel Fx Loop and a dedicated parallel Reverb Loop using his choice of reverb pedal with a panel mounted master control.
He likes this amp a lot.

I modified one of my amps to being very similar, circuit wise, to a Boogie MK IIC+, to see whether he liked the sound, which he does, but not as much as a Dumble.
He has now asked if I could build a Dumble instead of a Mesa into his, still unrestored 50 Caliber+, using the cab, speaker, hardware and transformers from the Boogie.
These are all in good workable condition, so I see no reason not to do it.

I bought 2xPCBs from Andrea/frusciante 89 (I like these 1/8" PCB boards), which are a good size for the Boogie chassis.
Having never built a dedicated Dumble amp; I would now like to get the TAG Dumble Experts' advice on which Dumble to build.
The owner is a Pro Musician and he plays Rock, Blues, Pop, etc. and likes the sounds and music of Robben Ford, Joe Bonamassa, Larry Carlton, SRV, Steve Lukather, John Mayer and similar guitarists.
I suggested the #102 or #183 or Bluesmaster, or maybe Tony's 102-183 mod.

What would you blokes suggest?

Cheers, Noel

[rootz]

Sounds like a fun project Noel! For more rock oriented work, I mostly a low plate classic, like the #124 before the Skyliner tone stack update. I really like the cleans in combination with single coils on that amp. OD is a bit rawer in my experience than high plate amps, a bit less smooth. Imho that makes the amp somewhat better suited for rock and blues rock.

[ngw]

Thanks rootz,
I was thinking of building two amps, so we can compare low plate and high plate.
He mostly uses his Les Pauls or SG, but he also uses a nice Strat.
He likes the smooth OD of a Zendrive and also likes to add more OD as well, like the Boogie.
We may keep the Boogie Graphic EQ after the OD as well.

[jazzbass]

Hi NGW,

I am attaching some photos of an amplifier that I made for a friend who plays jazz. He was in love with the shape of the Mesa Boogie amp and found a well-sized wood cabinet with a sienna speaker cover.

The choice for the music that he plays went to a JM / Wonderland clone on a chassis bought from TubeTown that has the same measurements as the Mesa Boogie chassis.

Certainly for your customer and for the music he plays the choice indicated by rootz is more suitable and if you need a chassis you know where to order it.

What are the characteristics of the transformers of the donor Mesa Boogie?

Hello

Franco

[ChopSauce]

Great...

I'm pleased to see that you also use the ol'school way to metalworking - which is rather efficient for one shots - tracing by hand rather than taping CAD prints...

I use to do my tracing on white paint masking tape sticked to the chassis. It is closer to paper so you can have that little bit of extra precision...

[ngw]

Hi NGW,
I am attaching some photos of an amplifier that I made for a friend who plays jazz. He was in love with the shape of the Mesa Boogie amp and found a well-sized wood cabinet with a sienna speaker cover.
The choice for the music that he plays went to a JM / Wonderland clone on a chassis bought from TubeTown that has the same measurements as the Mesa Boogie chassis.
Certainly for your customer and for the music he plays the choice indicated by rootz is more suitable and if you need a chassis you know where to order it.
What are the characteristics of the transformers of the donor Mesa Boogie?
Hello
Franco

Hi Franco,
That is a nice looking amp build. Any demo clips?

Since my original post, my client has decided he likes the sound of #102, so I am building him one, using any of the parts from the Boogie that are relevant to a Dumble.
The Boogie is in good condition and was working OK, when he bought it. After some time, it failed and he brought it to me.
Then I discovered the dodgy repair work and mods; and the burnt, conductive PCB.

The Transformers are Schumacher.
PT: EIA606-804. 561052 (4th week '88)
OT: EIA606-905. 562051 (5th week '89). Someone has also scribed V2147 9168 on one of the bells.
(The chassis is marked 3/89)

Cheers, Noel

[jazzbass]

Hi Franco,
That is a nice looking amp build. Any demo clips?

Since my original post, my client has decided he likes the sound of #102, so I am building him one, using any of the parts from the Boogie that are relevant to a Dumble.
The Boogie is in good condition and was working OK, when he bought it. After some time, it failed and he brought it to me.
Then I discovered the dodgy repair work and mods; and the burnt, conductive PCB.

The Transformers are Schumacher.
PT: EIA606-804. 561052 (4th week '88)
OT: EIA606-905. 562051 (5th week '89). Someone has also scribed V2147 9168 on one of the bells.
(The chassis is marked 3/89)

Cheers, Noel

Hi Noel,

I found this data on the web of a power transformer for Caliber 50+:

B + at 369v per side (not under load)
Filament Ac at 7.2v total. @ 3.6v per side.
Bias supply at 52v

The Amplified Nation diagram shows a secondary voltage of 330V (B +). This was the reason why I asked you about the transformer voltages.

For the amplifier to sound like a JM you should have this secondary voltage value.

I am attaching two clips of one of my JMs, the one built for a friend who plays jazz.

One clip is the recording of the very first start up after construction while the other is a song played by my friend with the bass pot almost at zero and the mid pot at 2 o'clock ... he says that so is jazz you play but I think a lot of the sound is also due to the type of guitar and PU mounted.
Third is a short videoclip

[ngw]

Hi Franco,
That sounds good; very Jazz oriented Clean.
We are more into the sounds of OD & Distortion, but we also love having a good Clean sound.

I think this 102 amp will be very good for the owner, sound wise and the Boogie cab and parts will provide a suitable platform on which to build it.
We will see and hear.

We are thinking of adding a post-OD tone stack and maybe making it switchable, so he can have a choice of HRM or straight 102.
We are also going to add another (completely separate) Clean channel, to provide an alternative to the Dumble Clean.

If any of you other Dumble experts want to add any advice, I am always grateful to receive your suggestions.