Can someone school me on the Studio Series/Caliber amps?

Pre Recto days. Boogie modified Fenders, Mark I-IV, Dual Calibers, etc

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Bottle Rocket
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Can someone school me on the Studio Series/Caliber amps?

Post by Strat_Lover » Tue Dec 14, 2021 9:47 am

Hello all,

First post to the forum, and the title pretty well says it all. I'm interested in getting one of these old Boogies. Here is my use case:

-Pretty low volumes, playing in duos. Currently use an old Princeton Reverb at about 3 with the volume dial, and up to about 5 with the bands I play in.
-A serviceable clean/edge of breakup sound, and a singing lead tone. For reference, I'm using an Angry Charlie with the gain at about 10 o'clock into the Princeton for this sound now.
-Seeing this new amp as a grab and go for jams/gigs with limited space. Ease of set up also important.

In my initial research, it seems the Studio 22+ w/EQ is what I'm looking for. I like the idea of separate channels on the Dual Caliber series stuff, but I've read these have a Recto based lead channel, which has never been my bag.

So, hopefully this will be a thread to share any and all experiences with these old amps!

Bottle Rocket
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Re: Can someone school me on the Studio Series/Caliber amps?

Post by Feedbacker » Mon May 09, 2022 2:36 pm

Just bumping this thread; Wiki has a great write up on the various Boogie 'Mark' amps and their tweaked versions, but I can't find much detailed info on the Studio 22.
I seem to find images of some with seven control knobs, some with eight. And of course with, and without, the Eq sliders.
Some have plastic rocker switches on the far right, others have the traditional chrome flick switches.
Some have the lower case 'Boogie' nameplate on the speaker grille, others have the 'MESA/BOOGIE' style (purely cosmetic, i know)
It's all very confusing - is there a guide or breakdown of the various models anywhere?

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Bottle Rocket
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Re: Can someone school me on the Studio Series/Caliber amps?

Post by HighWattGuitars » Thu May 12, 2022 5:29 am

Early models came with EL84 power tubes operating in class A and metal toggle switches. The Studio 22 was equipped with an EL84 duet and the 50 Caliber with a quartet. The tube sockets were mounted directly to the circuit board, even for the EL84 power tubes, which was probably not ideal. A couple years or so later, the 50 Caliber was re-designated at the "50 Caliber +" and its power tubes were switched over to a duet of 6L6-GC from the original quartet EL84, and I think they may have added a deep switch. Plastic (dielectric phenolic?) rocker switches replaced the metal toggle switches on all models in the series. I can't recall whether it was the rack mounted Studio Preamp or the powered combos that came out first. The Studio Preamp is basically the same circuit, with a couple extra switches to further adjust tone and gain. Other cosmetic differences involve the use of "Studio Series" on the early models and "Caliber Series" on the later models, or something like that. The combos commonly came with the 50 watt Eminence built "Vintage" speaker, Mesa model designation VS-12, which has since been discontinued. Interestingly, the Mesa Boogie brochure mentioned 3 models- 22, 38, 50, although no 38 Caliber was ever produced, outside of rumors. I spoke with an amp tech who swears having a 38 Cal on his bench, so there could be a few of them out there, and if so, I speculate that it's simply a rebranded 50 Cal with the EL84s. The 50 Cal was available as combo and head, but the 22 as a combo only, as far as I am aware. Personally, I don't believe that any of the 50 Calibers deserve the 50 watt rating, regardless of which power tubes were in use. Their output transformers were small compared to the Mark series 60 watt models. Tonewise, I can report only on the EL84 equipped 50 Caliber head. Compared to the Mark III, the 50 Cal's Lead channel is similarly aggressive, yet a bit smoother in the gain structure, slightly leaner low end, good mids, with the highs being "sweet", extended, and gently rolled off. Plenty of usable overdrive/distortion with nice "bounce" and dynamics. Rhythm channel is very usable, with good pure string tone at moderate gain settings, "sparkle and warmth", and a plenty of "bark" when turned up. The 5 band graphic EQ is very useful in further shaping the tone and achieving a good mix with other instruments. Overall, I deem the Mesa Boogie 50 Caliber head to be suitable for Metal, Rock, and Blues.
MkIII black
MkIII purple
MkIII red
MkIII blue
MkIVa (2nd of 2)
Quad (with FU-2)
Quad (with FU-2A)
50 Caliber (EL84)
Mk series 4x12 (4 cabs)
High Gain Amp Switcher
MkIIa Series 300 Imbuya
MkIVa (1st of 2)
MkIII Coliseum

Bottle Rocket
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Re: Can someone school me on the Studio Series/Caliber amps?

Post by quadboogie » Thu May 12, 2022 2:20 pm

Most 50 Cal's use a Mesa spec'd Celestion C90 (aka Black Shadow MC90)

There is a lot of confusion/bad info saying the + indicates a model has the GEQ (which is wrong). The plus is the mod with the lead master.

Another history thread: viewtopic.php?t=44396

IMHO, the 6L6 50 Cal+ is more than loud enough. Perhaps not as loud as the 60w Mark series, but louder than many 50W amps from other brands.

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Re: Can someone school me on the Studio Series/Caliber amps?

Post by wildschwein » Fri May 13, 2022 12:16 am

I had the Calibre 50+ during the '90s. Very loud, good enough reverb. Was a heavy beast for a 1x12. It's was good amp for me at the time. It sounded a lot better when you put it through a 4x12 cab.

Bottle Rocket
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Re: Can someone school me on the Studio Series/Caliber amps?

Post by Feedbacker » Fri May 13, 2022 8:31 pm

Thanks everybody for the replies and excellent info! Just what I was after... :mrgreen:

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