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Post by JohnH on Feb 22, 2006 1:34:13 GMT -5
It is time to move up from my little 10W Marshall practice amp, and I decided to start with a good cab, so that I can experiment with various amp designs. Step one was to get little Marshall to drive big cab. So this is my ‘MasterBlaster’ stack, so named after the double character in ‘Mad Max’, who comprised a miniature dwarf sitting on the shoulders of a large but stupid giant.  Its so strange looking that it is kind of appealing. I don’t think this is what Jim Marshall had in mind however, when he invented the 'Marshall Stack'. I installed a switched jack socket in the back of little M, such that plugging in the cab disengages the internal speaker. It was intended purely as a temporary measure. But the surprising thing is, it really works, it sounds pretty d@mn good and gets really really loud! The cab is a Marshall 8412 4x12 cab (a ¾ size cab), with 12” Celestions, all made in old England. It’s 8 ohm resistance, which matches the internal speaker in the Mg10. Plus most importantly, all the styling cues match – from the grill fabric, to the tolex, corner reinforcements, and also…… those Marshall logos. John |
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Post by night0wl on Feb 22, 2006 4:27:45 GMT -5
Nice one John!  I had one of those cabs with a valvestated 100 watt head a few years ago but it wasn't looked after and the head was playing up, aswell as the coverings coming off so I traded it in for a multi effects unit (Korg). Stupid really, I should have kept it! Cheers, Shane |
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Post by Ripper on Feb 22, 2006 12:08:15 GMT -5
Who runs barter town now huh?
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Post by UnklMickey on Feb 24, 2006 0:28:56 GMT -5
John,
i've always liked the idea of a combo amp and a cabinet or 2. lots of flexibility. very portable with just the combo. if you want things to "breathe", having 4~8 12s is the way to go. that "little" 10w amp isn't short on power, but not so much for tone. a 1w tube amp would be quite slick with that cabinet. you could get into the crunch zone without rediculous volume. of course there aren't many 1w amps out there. but i've seen a few DIY projects on the net. check out ax84.com if you're into that sort of thing.
unk
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Post by JohnH on Feb 24, 2006 1:21:53 GMT -5
Unk - you have read my mind. My plan is a small tube amp, to get me into tube circuitry, and have something I can crunch with without involving a visit from the police. Then build something a bit larger if needed. In the meantime, I'm all plugged in, and it impresses my 14 year old son.
It sounds a lot better than I thought it would, possibly due to some tube emulation circuitry that Marshall built in, called 'Frequency Dependent Damping'. Could be hype, but it seems to work.
John
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Post by RandomHero on Feb 25, 2006 2:36:38 GMT -5
John, I am terribly curious to know... what do all those shiny switches and knobs on that DIY Deity of a Hondo Strat copy do, exactly?
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Post by JohnH on Feb 25, 2006 6:35:56 GMT -5
RH - that guitar is the ToneMonster2, as on the schematics page. The three main knobs are volume, tone and blender. The switches are an on/off for each pup, an overall system series/parallel, and a neck phase reversal. Plus theres one more knob, not in the schematic, it has three positions and drives my built-in active circuit for clean buffer and two stages of JFET overdrive. Its a space rocket.
John
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Post by dunkelfalke on Feb 25, 2006 7:16:19 GMT -5
tone monster mod is great, works even with active pickups although some people in guitarnuts1 thought that it is impossible
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Post by JohnH on Feb 28, 2006 6:41:41 GMT -5
Further to the above, heres a view with the Marshall cab with the back off. Does anyone know the purpose of the wooden post in the middle? It is screwed to the front baffle, but not anchored to the back panel. I cant see what it does. If there was a screw anchorage to the back panel, I could believe it had a stiffening function, but there is no sign of one.  I have also seen a similar post on the larger and more mighty Marshall 1960 4x12, per this recent ebay listing: cgi.ebay.com.au/Marshall-Lead-1960A-Cabinet_W0QQitemZ7391971935QQcategoryZ10171QQrdZ1QQcmdZViewItemwith thanks John |
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vroom
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Post by vroom on Feb 28, 2006 9:05:06 GMT -5
I have the same post in my 5150 combo between the two speakers. It is also only attached to the front. Don't exactly know its full purpose.
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Post by UnklMickey on Feb 28, 2006 9:56:23 GMT -5
...If there was a screw anchorage to the back panel, I could believe it had a stiffening function, but there is no sign of one. ... is the post tall enough, so that when the back is on, there's pressure on the post? |
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Post by Ripper on Feb 28, 2006 12:01:54 GMT -5
It looks like just a brace.
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Post by UnklMickey on Feb 28, 2006 13:41:01 GMT -5
maybe it's "tonewood".
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vroom
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Post by vroom on Feb 28, 2006 14:06:00 GMT -5
I suppose (on mine, at least) it could act as a brace, to prevent the back from bowing in.
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Post by JohnH on Feb 28, 2006 14:45:24 GMT -5
There doesn't seem to be any positive pressure on it, so I cant see it being effective as a brace for stabilizing the resonance of the front If that was the intent, it would surely be better if there was something to attach it positively to the rear panel. It could perhaps help to reduce mechanical damage if you kicked the front. I don't plan on testing that however.
J
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Post by UnklMickey on Feb 28, 2006 14:57:34 GMT -5
if it touches, or comes close to touching, the back, without serious pressure or anchoring, that would be kinda lame. when the vibrations in the front and back are out-of-phase, that post would be hammering against the back panel. i guess it would keep you from melting down your speakers. it would sound bad long before you got to a level that would harm the speakers.
i wonder what J.M. has to say about it's purpose.
unk
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Post by Runewalker on Feb 28, 2006 22:34:36 GMT -5
John, I am pretty sure it is a "floating brace" engineered by same countrymen who comandeered the superb electronics of Lucas in Jags.  I gotta go with Unk's Tonewood, because there has not been enough spurious debate on tonewood in the forum lately. |
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Post by UnklMickey on Mar 1, 2006 18:00:36 GMT -5
...Does anyone know the purpose of the wooden post in the middle? It is screwed to the front baffle, but not anchored to the back panel. I cant see what it does.... found some info for you: www.18watt.com/Storage/1960A-Slant-Cab_rev1.pdf |
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Post by JohnH on Mar 2, 2006 4:25:53 GMT -5
Thanks Ukl, that explains it. So it is a brace from front to back, that relies on pressure to keep it in contact. If so, it would be effective, since as the front pushes back the back would push forward, and the brace would link the two, keeping the cab more solid. Ill see if mine is in fact, bearing as it is supposed to.
+1
John
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Post by dunkelfalke on Mar 2, 2006 7:21:46 GMT -5
of course there aren't many 1w amps out there. but i've seen a few DIY projects on the net. check out ax84.com if you're into that sort of thing. this reminds me of something: www.madamp.biz/g2.htm89 euros for the kit, substract 16% vat when shipping outside eu. |
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Post by UnklMickey on Mar 2, 2006 17:14:42 GMT -5
Falke,
that amp looks a bit too limited, just one tone control. and the chassis looks wimpy. but hey whaddaya expect for 90 euros! a similar low powered amp kit from doberman (ax84) costs $195 US!
the transformers and tubes would cost as much as the G2 kit here. it sounds like a decent place to start, maybe add one more tube in the preamp and use a bax tone circuit.
bottom line: it doesn't cost much, so value/$ is still high. good find!
John,
i'd stretch a string across from the edge where the back panel sits. if that post doesn't stand at least 5mm proud of the line, consider adding a rubber pad and/or running a screw through the back into the post.
unk
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Post by dunkelfalke on Mar 3, 2006 1:35:48 GMT -5
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Post by UnklMickey on Mar 3, 2006 4:21:49 GMT -5
hey Falke, this looks like pretty good value too.
either one looks like a decent platform to start from. this one has lots more room to work with.
the tone-stack is likely fender of marshall (with the middle control that is actually a contour control). but that could be easily changed and configured to a bax.
5 watts is too much for power amp distortion at low volumes. but, there are ways of downsizing that design.
in general, i think these guys give you a lot for the money.
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Post by JohnH on Mar 3, 2006 17:19:35 GMT -5
Dunkelfalke - those madamps look like a very good option for a homebuild, without needing to do everything from raw materials. Good value too When i get to this - I will see what it would cost to ship to Australia.
Unk - my 'floating brace' makes slight contact with the back panel. Its engaged but no more than about 1/2mm overlength to cause positive pressure. A small pad will be added, maybe a screw also - which should lock it in even if the speakers are inflating the cab at high volume. Without this, an inward pump of the speakers will push the back back and the front forward, releasing pressure on the brace and causing a nasty noise on the return. I havnt heard this happening, but I also like to have design that I can believe in!
Or maybe all the hype about the 'Marshall sound' was missing the point. It wasn't about overdriven tubes driving stacks full of vintage Celestions. It was really just a stick of 2x2 rattling on a sheet of plywood.
John
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Post by UnklMickey on Mar 3, 2006 17:34:30 GMT -5
John,
that's funny!
my guess is, the reason you haven't heard any hammering yet is, you respect the neighbors. with some serious volume and/or low frequencies, that cab would likely make some ugly sounds. improving the linkage can't be anything but good.
this discussion has made me wonder what sort of strange sonic variations one might come up with, by simply adding mass to the midpoint of the rear panel and also to the midpoint of the front. instead of stiffening the system, you would be changing the resonant frequency of the panels. might be an interesting experiment on a shop-worn cabinet. i wouldn't recommend it on anything of value. could cause some structural weakening of the panels do to serious flexing at resonance.
unk
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Post by dunkelfalke on Mar 3, 2006 17:51:55 GMT -5
will by me a madamp too some day (when i have the money, now a custom neck is a higher priority), but i would buy me this one: www.madamp.biz/a15mk1.htmeven if i only play at home - will play it through a dibox and a hybrid combo ;D |
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Post by JohnH on Mar 4, 2006 15:45:30 GMT -5
I put a 2mm layer of closed-cell foam on the end of the brace, and fixed the back down. With that, there is now definitely some panel flex induced in doing up the screws, locking the front panel positively to the back. The foam may also add some damping to higher resonances. It is hard to compare the sound before and after, but I can believe (or am willing to imagine) that the bass is a bit tighter.
John
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Post by UnklMickey on Aug 16, 2006 11:12:39 GMT -5
...So this is my ‘MasterBlaster’ stack, so named after the double character in ‘Mad Max’, who comprised a miniature dwarf sitting on the shoulders of a large but stupid giant.
... hi John, i see you have finally started using an avatar. you were definitely the most prolific poster without one. (now that "honor" goes to Mini-Strat_Maine.) i see that the "MasterBlaster" has a new mid-section, your D ieS eL 401  so what do you call this thing? the D ieS eL powered MasterBlaster ? the snowman stack? unk |
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Post by JohnH on Aug 16, 2006 22:18:27 GMT -5
Its called the 'Three Bears' - and I can tell you that Mommy Bear is 'b!tchin'!. Baby Bear has nothing much to do these days except to sit up there.
BTW - as you can tell from the guitar, the whole stack (or more accurately, 'pile'), really is 10 feet high.
John
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