Swamp Thang or a Cannibis Rex for MMB?

Trying to decide between the two for my MMB amp to get the most out of the amp. I play Country and Classic Rock some blues but not as much as the other two. I tell you the sound clips at the Eminence site really does not tell me much but then with computer speakers I suppose not. To me most of them clips pretty much sound the same. :roll:For those that have them what do you say .Both are rated at 102 DB but it seems like they are saying the Cannabis Rex is louder because it only takes a watt to push it to that DB but is it the same for the Swamp Thang too as they are both rated 102 DB though one is 50 watts (Cannabis Rex) and one is 150 (Swamp Thang) The MMB is 12 watts but looking at the ratings is the 50 better for this or does it matter is the 150 good as well. Reason I am asking is the 150 would be more versatile for me I could run my PA 100 into One 12 if I wanted to and use the MMB as a cab too. If I went with the 50 watter it would be just then for the MMB.

I think a Celestion Alnico Blue would be my 1st choice and then the Cannabis Rex

There are many ways to get more from a Musicmaster Bass besides speaker swapping. If you're speaker swapping go for the tone you like rather than volume. If you're going for volume get a Red Fang. It's both an incredible speaker and an incredibly expensive speaker. I thought it was expensive back when it was $170, then Eminence looked at the $300 Celestion Blue.


The MMB has the wimpiest power supply I've seen in a tube amp. The PT is 250-0-250 (volts) for the original MMB with 6AQ5s. For a while I thought Fender started with the 6V6 version then cheaped out to 6AQ5s. Nope, it was the other way around. Fender kept the wimpy "6AQ5" PT when they switched to 6V6s. 6AQ5s are cool if you don't want ear shattering volume especially with the oriignal funky CTS speaker those things came with. 6V6s have more potential but they're limited by the power supply.

If you have the 6V6 version there's more volume on tap with a transformer swap. Don't push the 6AQ5 version. Weber's low buck WO22772 "Champ" transformer has taps for 300-0-300 and 330-0-330. The 300-0-300 taps will wake that little sucker right up. Stick a 250 ohm 5 watt resistor in your shopping cart while you're at Weber VST. Replace the stock 220 ohm bias resistor if you do the transformer swap.

There's a more complicated trick for the 6AQ5 version (double the power!) but let's keep it simple.


A replacement output transformer may have an edge on the stocker. The Allen / Bill M TO20 is the pick of the litter. Way less expensive than a Red Fang and a good way to remove another impediment from the poor MMB.


While we're removing impediments remove the .0047 capacitor from the input. Replace it with a jumper. You might want to change the adjacent 470k grid leak to the standard Fender value of 1 meg while you're in there.


First things last: If you follow these steps in order you're beyond the limits of the wimpy stock filter caps. Replace 'em with 22uf / 450v and never worry about 'em again. There's no reason not to use a 47uf / 450v for the first filter.

Thanks muchxs thats very informative as ever. Ill take that info and run with it!

OK The Caps already have been done with F&M caps No way can I afford a Red Fang so that is why the speaker Change right now the speaker in there is an Eminence but not sure what model it is not one of the series speakers. I do have the 6v6 version. OK so your saying the OT is for the 6aQ5 and for the 6v6 which I have do the PT swap at 300 0 300 and change out the Bias Resistor and dp the input work.

OK Checked out the transformer I got a gig May 12th think I will take the money and buy the transformer so what kinda wattage increase are we talking about with the swap? I will contact you with any questions after I get the parts in hand.

OK Checked out the transformer I got a gig May 12th think I will take the money and buy the transformer so what kinda wattage increase are we talking about with the swap? I will contact you with any questions after I get the parts in hand.

"No name" Eminence speaker is likely a Special Design. Eminence makes speakers for Carvin, Randall... even Victoria and Peavey (and just about everyone else)! Yup. Buy a Victoria, it usually comes with an Eminence. Most of the OEM Eminence speakers put out at least 98db.

The hassle with the MMB PT is it's low voltage / low current. That's great if you want to keep it down so the neighbors don't complain.

Couldn't tell you what it makes for wattage with the transformer swap. Let's just say more than stock.

You can not go wrong with the CR, and it would be my first choice of the two for Blues, but for clean Country I would say Swamp Thing. I don't think either will disappoint.

OK Checked out the transformer I got a gig May 12th think I will take the money and buy the transformer so what kinda wattage increase are we talking about with the swap? I will contact you with any questions after I get the parts in hand.

The PT change might get you to 18w, 15 for sure. That is less then a 2db volume increase. If the current speaker is 98db as muchxs suggests, changing to a 102db speaker gives you twice that for about 1/3 more cost and a whole lot less work (not that the PT change is a whole lot of work).

Good to know Thanks Maybe both the speaker and PT would be a good choice.

Good to know Thanks Maybe both the speaker and PT would be a good choice.

Now you are talking. If you still need more, you could convert it to fixed bias for very little money and have a stripped down Deluxe. That could get you up around 22w.

I think the PT change and speaker change would make it pretty good.

I thought the MMB is already fixed bias?

Nope, the 220 ohm resistor muchxs suggests you replace with 250 is the bias resistor.

Remember, one of the ironies of tube power stages is that fixed bias is usually adjustable (so much for being fixed) and cathode is almost never user adjustable.

Actually, with the Weber PT, you could use the 330-0-330 windings and get your 22w in cathode bias, but that would require a lot more R&D on your part.

OK I looked and seen it was cathode bias. For now I think I would just go with the speaker change and then the PT.

The PT change might get you to 18w, 15 for sure. That is less then a 2db volume increase. If the current speaker is 98db as muchxs suggests, changing to a 102db speaker gives you twice that for about 1/3 more cost and a whole lot less work (not that the PT change is a whole lot of work).

The full package is a lot more than 2db.

You know how it goes... it's only as strong as its weakest link. I'm sure you know how that works (doesn't work) with hi-fi. Wimpy power supply = wimpy rig. Can't push the bass if the power supply is barely adequate.

Jumper the .0047 on the front end. That's more than 2db.


Fix the built-in "poor man's power scaling". I'm sure you know what an inadequate power supply does under hard transients. It might be "2db" (spl) on paper but improved transient response makes it feel like a lot more. I haven't run frequency sweeps on one, I just make 'em louder.


Last bottleneck to address, swap in the magic Allen / Bill M OT. Bill M can give you details of how it's built and what it does. I figure the stocker rolls off the bottom end (yeah, just what I want in a "bass" amp :roll:) while the TO20 keeps on goin'. Weak power supply plus wimpy OT makes an MMB do a Gibson GA18 impersonation. That's another amp that looks good on paper.

OK I will do the transformers first and change the input then go from there.

I bookmarked both the Weber and Allen pages so I can find them fast when I order.

Yeah, the 2db was a for the PT only, and for a 6V6 amp, that is the place to start. The bigger PS cap should do much for improved transients as well. But still, to get the most out of the PT, you need to change the OT as well. To get the most out of the OT, you need to change the PT. He said he was not able to afford a Red Fang (I got my first for $129 new delivered, boy was I shocked when I went to get another one) so price was a consideration. If the sound of the new higher efficiency speakers suits his needs, I still contend that a speaker change is the "most for least" option.

Then he said speaker and PT, Oh Yeah. And with the weber PT offering higher voltages, maybe the Allen Deluxe OT is a better choice if loud and clean is the target. It would be the next step.

Well with the transformers I can go one at a time ordering them if money is tight since both are around 50 bucks give or take.

Weber 12F150 sounds really good in one. The muchxs suggestions or Hasserl mods work very well too...and are cheap.

I will do the mods that Muchxs suggested first then maybe a speaker. I am not much for modding amps just to mod them, but I can see where what Muchxs said make sense. If the Trannies were for the 6AQ5 MMB then when they changed to 6V6s Fender should have upgraded the transformers as well. Cost cutting on Fenders part from what it looks like. So this is not as much a mod, but doing what Fender should have done. That works for me.

JH45gun, inspired by this thread I just dropped a C Rex into my MMB. Lots of extra volume and the tone much bigger to my ears too. Im not competent enough to carry out mods but may get them done in the future. Good luck with yours.. Im eager to gig this thing.

Good to hear it. I am thinking Muchxs mods or changes with the transformers and other input changes should make this amp better. Then add a efficient speaker will make it all the better. Should have a little rip snorter in a small package.

Last month I picked up a Fender Special Design (Eminence Legend) from a HRDX.
I always liked these speakers despite popular opinion. Got it brand new for $20, and .swapped it out in my MusicMaster Bass Amp. It sounds great!!! The improvement over the stock old speaker was so drastic, this has become one of my favorite amps. We be jammin!

Yea the Eminence speaker I put in mine made a difference also. We will see if it stays after the Transformer and input mods.

I have the 6v6GT version of the MMB. It came with an Eminence Legend(Fender Label) just like Rubyraes. It has plenty of volume and great tone. I have some low efficiency 12 inch speakers that I have swapped in there and that makes the tubes work harder so you get more tube distortion at lower volumes.

I am not looking for more tube distortion I prefer to keep it cleaner I use pedals for distortion.

Well gonna order the Transformers the first part of June when I get paid to cover the rest of the cost. I have 90 dollars put away so that covers most of the cost. With shipping cost for both transformers is around 116 dollars plus tax if any. I have the resistors on hand already.

Looking forward to seeing how it works out. After a couple of weeks with the c rex ive swapped to a weber alnico sig 12, even better in my opinion.. the top end sparkle is back.. just need to do the resistor mods as detailed.

I will post the results when I get the parts in hand and do the swaps.

Blah,blah, blah.. Snake oil sales...Don't waste your time and money for so little in return.. Buy another amp.

TDPRI member OaklandA gave me a heads up on another transformer I had previously overlooked. He suggested the Allen Amps TP24. Pretty sure it's another BillM Super Blues Junior upgrade. It is not a straight drop-in for the MMB, the rectifier circuit must be changed. If you can make it work (I can!) there's enough juice for 6L6s.

Pros and cons:

The Weber 22772 is $42. It has five more wires than you need so you need to deal with the extra wires. It will run 6V6s. Don't try to make it run 6L6s.

The Allen TP24 is $75. It still has a couple more wires than you need. Rectifier circuit needs to be modded.


I'm workin' on it... I have a cool "drop-in" rectifier from Fender's parts bin.


I thought OaklandA was talkin' about the Allen TP25 ($89). Tempting! But...

The TP25 is 310 volts on either side of the center tap. We'll use the quicky no load calculator for raw voltage. 310v x 1.44 = 446v with the MMB's SS diodes. That's way high for 6V6s and awfully close to the limits of 450v caps in the power supply. The stock caps are 300v.


I'm tryin' to point out easy low buck solutions.

In theory an MMB chassis is on its way to me. I'll post in Shock Brothers after it gets here.

...

Blah,blah, blah.. Snake oil sales...Don't waste your time and money for so little in return.. Buy another amp.

Changing the power supply from inadequate to adequate isn't "snake oil". Neither is converting a bass amp to work properly for guitar.

The idea is to take a $300 amp and make it work like something a lot more expensive.

Think I will stick with the original plan and keep it 6v6's. Because if I want 6l6's I have a 100 watts of goodness coming out of a quad of them in my PA 100.

Think I will stick with the original plan and keep it 6v6's. Because if I want 6l6's I have a 100 watts of goodness coming out of a quad of them in my PA 100.

Just sayin'. OaklandA pointed out the alternative iron, I looked into it and I'm passin' it on.

Allen says the TP24 gives 365v on the plates @ 150ma. That's 75v more than stock and enough for 6L6s. Just because it will run 6L6s doesn't mean that's your only option. It will run 6L6s or 6V6s.

I'm tempted to whip up a couple test mules to demo the various options. In my spare time. When I have spare money.

OK just for curiosity what are the changes you speak of with the Rectifier circuit? Larger Diodes?

Never mind I looked at the tranny and seen it asks for a Full Bridge Rectifier circuit.

Blah,blah, blah.. Snake oil sales...Don't waste your time and money for so little in return.. Buy another amp.

What Muchxs says makes sense with this amp I am not one for modding every thing I own I figure most things stock as designed are fine with the exception of speaker swaps maybe. But since this PT is under powered for 6v6's makes sense to fix that issue along with a beefier ot.