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PostPosted: Sun Jan 17, 2016 1:18 pm 
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Bottle Rocket
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Joined: Fri Jan 15, 2016 10:47 am
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As a long time lurker, I sought information about 1x12 combos that would be suitable for my regular out of town gig, 1.5 kilomiles north of my usual haunts. Found one and signed up to post about it (and other stuff).

Here's my notes and some pictures:

Mesa Son of the Original Boogie
Arrived 1/16/16 to FedEx Office after trying to get it delivered since 1/14/16

Inspection on arrival:
Non-original snakeskin tolex peeling because glue is not holding. Needs repair or I will strip and recover some time. OK for now.
Non- original plastic corners installed on rear top. One is broken, perhaps due to blow in shipping. Will replace with metal corners.
Checked tubes. All intact.
Mesa branded Celestion MC-90 8 ohm 90W Black Shadow said to be Kurt Mueller 444 recone obtained by seller.
SOB fired up OK.
Pots were a bit scratchy.
Volume 2 (lo input) OK up to 5, but amp started to cut out and get what sounds like blocking distortion with the master up all the way. When vol 2 was dialed below 5, sounded ok, but noisy.
Volume 1 (hi) relies on vol 2 as well. This channel sounded unhealthy. Likely microphonic v1 Sovtek 12AX7wB.
Presence control said to be not working. Noticed it intermittently cut output to zero after above 2 on the knob. Suspect this is no presence...likely Limit control (current limiter at PI).

Initials and names in chassis: Tina near main board, LJ by OT, BA by power supply board
Markings on chassis rim: SOB, JC, J2
Markings on both chassis ends: SOB
Markings on chassis top - between V1 and V2: 12AX7, at V3: 12AT7, between V4 and OT: LJ then J1382
Might this be an early 1982 build?
Serial number stamped by speaker jacks: S404

Tubes look new or low hours.
V1 Sovtek 12AX7wB
V2 Sovtek 12AX7wB
V3 EH branded 12AT7
V4 GT branded GT6L6B Sovtek 5881WXT stamped 98
V5 GT branded GT6L6B Sovtek 5881WXT

Observations from under the hood:
Replaced electrolytic caps in power supply. Cannot see marking of values. Bundle of caps on board proximal to controls replaced with one on board JJ 47M/500VDC and one off board and unsecured multi section radial can supported only by soldered leads near rear of chassis. Not stock. Main filter caps unknown make and specs (clearly electrolytic, though marked PET which I usually see associated with plastic caps...). Two smaller electrolytics on PS board replaced axials with Xicon radials (47M/160VDC?).

Presence (Limit?) has wiper to ground and A (1) to a transistor-like component, likely a diode, marked from top to bottom:
?? TC
?508
8121
Where ? Indicates uncertainty of the making
There is also an unused socket for a transistor with the middle leg disconnected but also possessing a solder ball. Looks like it could have held the Limit diode but currently unused. I heard that this was used but in the chassis shots I have seen, this socket was either absent or not located at this precise point on the board.

Some orange peeling on the Sprague 0.1/400VDC caps on V2.

Sprayed out pots with Deoxit and ran wiper back and forth ten times. Need to chase with CaiLube, but I'm out at the moment.
Sprayed jacks out with Deoxit and plugged/unplugged TS plus ten times.
Sprayed out switches with Deoxit and flippped switches ten times.
Sprayed out tube sockets with Deoxit, waited 2 min, chased with Deoxit Gold, plugged and unplugged tubes ten times.
Cleaned chassis.
Removed knobs from pots and reinstalled so they lined up with the markings except for Master control which was frozen to the the shaft, so I left it alone.

Play testing:
Reinstalled chassis, plugged speaker into 8 ohm jack and turned on power. Tubes lit up OK. After 5 min warm up, flipped standby and started working knobs. Diming the master led to hiss and high pitched hash. Turning up volume 2 added hum. Turning up 1 did not add as much noise and found that using input 1 with volume 1 at 9 o'clock and volume 2 at 3-5 on the dial sounds pretty good for big clean tones (as I prefer). Needed to keep master down to 2 to keep neighbors in my beach condo happy, but turning it above 4 added unwanted noise anyway. Was able to get a gigable volume :twisted: before the neighbors howled in protest :lol: . Need to dial in the EQ, but looks like with humbuckers on my Axis SS rosewood, a setting of 777 for Treble Bass and Mids is OK. More time at volume needed to get the Strat in the ballpark, but shouldn't be tough on the gig. The Limit knob now works, since I lifted the middle leg of the unused transistor socket that was up soldered but contacting the board.

Except for tolex peeling up and the corner being broken, I am satisfied. I will likely replace the corners with metal corners and try to glue down the tolex better before I schlep it up to New England. Will roll tubes to see if I can get the noise down. Will try a excellent NOS 5751 in V1 for sure. Must secure power supply cap that is not mounted to chassis before I gig this!

tldr, right? :lol:

As soon as I get the pictures up in my account, I'll post them here. I want to thank the many of you that provided content that helped me hunt this puppy down and get it sussed out swiftly. I hope the info I posted (and pics to come) will assist somebody else some time. I will also try to help out around here as I can. I have been performing and recording for a few decades, built a couple amps, maintain my amps, and might be able to share a few things that are useful.

DS


Last edited by dexter.sinister on Sat May 21, 2016 1:16 pm, edited 2 times in total.

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PostPosted: Sun Jan 17, 2016 3:58 pm 
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Bottle Rocket
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Joined: Fri Jan 15, 2016 10:47 am
Posts: 12
Some pics (weird how they got flipped between Picturetrail and da Boogie Board! Look fine when I open on the hosting site...):

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PostPosted: Tue Jan 19, 2016 6:03 am 
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Mark III

Joined: Tue Sep 20, 2011 11:15 am
Posts: 191
Man!The power supply section of that amp has been butchered.You should have it repaired/returned to how it should be.


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PostPosted: Tue Jan 19, 2016 11:58 pm 
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Bottle Rocket
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MK IIB wrote:
Man!The power supply section of that amp has been butchered.You should have it repaired/returned to how it should be.


Word. The seller told me that the guy that did the work makes his own amps, but is "impatient" about repairs. I'd love to have a better schematic of the SOB and a layout. Failing that, I am likely to draw mine own up from what I see and from photos.

Considering swapping in Solens ("fast caps") for the PS electrolytic because I have them, and have used them in my own "Dumbloid" builds in the past and liked the result.

Willing to keep the Limit for now, though I will nuke the unused socket for the "transistor" diode.

Definitely rolling tubes and contemplating rolling neo and alnico speakers to 1) reduce mass and 2) dial in the tones at the level I perform at on the northern gig (marimba, kora, acoustic guitar, percussion of various sorts, traps, voice). Loud enough but not rawk. Y'all feel free to toss idears thisaway fin you wanna.

Tx. DS


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PostPosted: Thu Jan 21, 2016 7:12 am 
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Mark III

Joined: Tue Sep 20, 2011 11:15 am
Posts: 191
I've also got a SOB 60 watt Combo.I mainly got it as I wanted the MS-12 speaker that was in it for my Mark IIB and I got a good deal on it.Once I got used to it I really liked the tone.I mainly used channel 2 with the volume up full for a nice slightly broken up "clean" sound and then pushed that with an overdrive pedal into sweet ovedrive.
Channel 1 with a les Paul got me that Boogie singing overdrive sound no problem.
Here's a couple pictures showing the stock power supply section and a schematic of the SOB.




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PostPosted: Sat Mar 19, 2016 8:17 pm 
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Bottle Rocket
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Joined: Fri Jan 15, 2016 10:47 am
Posts: 12
i picked up an Alessandro/Eminence neo 12 and a home brew pine combo cab for my SOB. Did a little repair on the power supply, popped the chassis in the new cab, hooked up the new speaker, and I now have a gigmeister combo that is 37.8 pounds and gets whats I likes going on for the Taxachusetts band. I will be schlepping it north next month for rehearsals and we start touring in May.

Not a bad little amp for the price and barks like a big dawg. I love big iron, but cartage is a be-yatch, so I think the neo/pine reboot will be fine so long as the orangutans keep their mitts off my gear.

Having fun!


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PostPosted: Sat May 21, 2016 11:40 am 
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Bottle Rocket

Joined: Sat May 21, 2016 11:21 am
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Nice, but yeah, yours is definitely not original. I bought my SOB new in 1986 directly from the factory...it was $650.00 new btw, and that included reverb, shock mounted chassis, and Celestion speaker...each of those options added $50...it was $500.00 for the base model...I do remember all that...
It actually didn't come with instructions or anything, but I did get a manual of sorts later, which has suggested settings and the like, and I believe has a schematic as well...but it seems like you have all that by now. And the original tubes are made in USA, and say "Mesa Boogie" on them...

I don't have many pics of it, but here's one...well, behind the guitar anyway...the Tolex covering and shock mounted chassis were actually a combined option...they came together for $50.00...

I have the Reverb knob on mine instead of the Midrange...and my last knob says "Limit"...

Image


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PostPosted: Sat May 21, 2016 12:39 pm 
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Bottle Rocket
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^^^

Nice guitar! What is it?

Hey, do you use your limit? I haven't found it to be useful, especially since I play my SOB wide open (ch 2 vol 6-7, master dimed) into a Freyette Power Station to dial it to the room (no attenuation in the rock bars and for sessions, choked back a few clicks for the bar/restaurant gigs). No verb, so I use the Power Station post OT loop and drop in an EQD Dispatch Master delay/verb for a little atmosphere as needed.

Just picked up a Mark V 35 for a gig a couple thousand miles north (sitting at the airport with my fly rig right now, in fact). Planning on leaving it there until the summer festival/tour thing dies down and then cart it back. Won't be able to compare the SOB and V:35 until then. Should be fun.

d.s


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PostPosted: Sat May 21, 2016 12:54 pm 
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Bottle Rocket
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Joined: Fri Jan 15, 2016 10:47 am
Posts: 12
This is the daily driver:

'73 Strat hardtail with a bridge bucker
SOB rehoused in a pine combo cab with an Alessandro neo 16 ohm
Freyette Power Station to match the 16 ohm speaker to the 8 ohm amp and to provide a post-OT effects loop
The loop has a Suhr MiniMix with an EQD Dispatch Master in its loop, so the delay/verb is in parallel to the straight SOB output

Cranked amp, dialed back with the PS to match the room.
POW!

Image


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PostPosted: Sun Sep 03, 2017 7:16 pm 
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Bottle Rocket

Joined: Sat Apr 29, 2017 8:07 pm
Posts: 9
I want that cabinet!!


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PostPosted: Tue Feb 06, 2018 11:48 pm 
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Bottle Rocket
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Joined: Fri Jan 15, 2016 10:47 am
Posts: 12
Craigslist score. Between the neo speaker and this cab, I made cartage work way more better(er). Gotta keep touring costs down to make it work for regionals...


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