Very straightforward. No crappy intro music blasting in your face, no hyper video production making you dizzy, no maniac narrative insulting your intelligence. In other words, excellent!
Picked up a broken FMMB. I had built a head unit for my Rivera-era Champ II chassis(that I found without the cab) when the FMMB came along. Decided to put the Champ II in the FMMB cabinet and let the FMMB go into the head unit. I'm pulling the FMMB board and installing a Riveria-era Bassman 20 board and tone stack instead. Keep the FMMB interstage transformer for phase inverting in the bassman 20 circuit. Remove the FMMB faceplate and replace it with a generic champ faceplate so I can drill out room for Mid/Bass knobs. I'll screw it into the inside base of the head unit so they stay together. Heads up about the FMMB fiberboard. Check for voltage leaking across the waxy surface. I think after 1972, fender went overheard spraying the fiberboard with wax. Over time it gets contaminated and begins to conduct. Acetone and naptha can wipe off some excess wax if you find voltage on the board. I liked all the suggestions in this video. I noticed that the input jack wiring was overlooked in forums but is an obvious place to increase gain. Adding a fuse holder is a great safety feature. Add a reverb and tremolo pedal and you're there already!
The use of an interstage transformer in lieu of a PI (as Gibson did in several amps in the '60s) was an effective cost saving device, but in that, it also could sound very good. Had budgetary constraints not ruled the day here, and another pre-amp tube added (along with more tone controls), this might well have been a great platform for a budget line of amps..but that possibility was lost many years ago...
Nice mods for this little amp. The price has gone up for these over the past few years. I have a Bantam Bass amp and I removed the rectangle Yamaha speaker and replaced it with 4-10's. After a cap job, the Bantam Bass really sings.
I did the tone stack mod and a Jensen C12N on my 69 Musicmaster and it sounds great. Sweet natural final stage overdrive without blowing your head off.
I hate the stock ‘65 Deluxe Reverb RI Jensen C12K. But in the ‘72 MusicMaster Bass Amp it sounds great. What an overkill at 100W, but it’s destined for repurposing in the ‘72. I put a 3-prong with MOV surge protectors and fuse holder and fast blow 1A fuse for safety.
Thanks for describing the mods, and providing a sound demo. I have a few questions though: 1) Since this is a bass amp, why was it modded into a 5F2 Princeton, and then demoed with a guitar? 2) The clean tone (e.g. 12:33 to 12:54) actually sounds bad to me. It has a rough, random "tremolo-like" quality to it. Could this be due to a faulty tube?
The point of modding this little tube amp is FOR better guitar tone! The arguably best tube guitar amp ever made was a bass amp! As for the Tremelo like tone you hear… I used a Strat… with a Tremelo… I would judge the nuances of ANY amp or guitar from a TV, PC or phone speaker!
Thanks for your reply, and clarification 🙂 Although the tweed Fender Bassman did indeed make a great guitar amp, I initially thought that the mods for this amp were done so as to make a better *bass* amp. When you mentioned "tremolo", were you referring to the "tremolo" (actually vibrato) arm on the Strat, or a tremolo pedal? Even so, to my ears, whatever the cause, it didn't sound right. Sorry! 🤷🏻♂️🙄
How much do you charge to do these mods? I’m in Columbia SC and have had one sitting for ages. It has a pretty decent speaker and for high gain lead I’m ok with it as I prefer a dark sound, but without the mods it’s terrible for cleans. Thanks for the video!
Thank you for posting this. Very helpful! I'm about to tear into my MMB amp. I'm curious -- when you are replacing the caps and such, is it best practice to remove the fiber board / circuit board? Or do you make the changes with the board left in place? Thanks in advance.
I did your mods based on this video, and the only problem I had, that I can't solve, is that after adding the 1M ohm resistor, one channel has great volume and the tone control is very good, but the other channel has a much weaker volume. I've checked and wired and rewired but no luck, regardless of the jack I install the resistor on. Any suggestions? Thanks.
As a Musicmaster is a single channel amp, I’m guessing your problem is with the second input, which is wired for a slightly weaker out put from the factory. The 1 meg resistor in the #1 input prevents signal from shunting to ground. Without one in #2, some signal does, hence less volume.
very interesting any way to get more than 12w out of it - i mean your princeton would be pushing 16-18w right ? and is that a 12 inch speaker - would it be possible to fit 2 x 10 inches
do you know what years the musicmaster had the tube rectifiers? I learned that at some point they used ss rectifiers, but before that they had a tube rectifier.
@@recycledsound I like amplifier mods but right now I use it also with effects pedals. Having a really good, strong efficient speaker made 1000 percent difference in my amplifier. I put some good quality Tubes into this GEM and it also make a great difference.
I’ve never opened up a Musicmaste amp. The interstage transformer always intrigued me. Enough so that I may build one some day. My blackface Princeton Has analog pots from the factory.
i imagine it was voiced for bass ? also i think that speakers that came with budget fenders from the 80s were pretty poor so maybe the late 70s too.. i suppose the classic fender guitar speaker is a jensen
Not sure what makes these amps so great if they have to be so heavily modified. It would have been a valuable video had you recorded the sound before the mods.
My MMB has a push-pull on off volume pot. Did you change this to and on off switch? I'd like to change my volume pot to 1meg, but it has the on off switch mounted to it and no chassis holes for an on off switch.
Well, its actually a turn clockwise to 'click on' pot and there is nothing out there like that. I wanted to somehow change the guts of the existing pot with a 1 meg and re-assemble it but the old original pot/switch cant be dis-assembled.
Bill Kasper are you sure! I've used them many times! As you can see in vid, our example has a separate power switch. If you can't find a switch pot, you can easily add a power switch to the rear of the chassis. Drilling a hole there won't hurt anything and I doubt seriously it would have any impact on value. Just keep it as close as you can to same area as where the power cord comes in.
Very straightforward. No crappy intro music blasting in your face, no hyper video production making you dizzy, no maniac narrative insulting your intelligence. In other words, excellent!
Picked up a broken FMMB. I had built a head unit for my Rivera-era Champ II chassis(that I found without the cab) when the FMMB came along. Decided to put the Champ II in the FMMB cabinet and let the FMMB go into the head unit. I'm pulling the FMMB board and installing a Riveria-era Bassman 20 board and tone stack instead. Keep the FMMB interstage transformer for phase inverting in the bassman 20 circuit. Remove the FMMB faceplate and replace it with a generic champ faceplate so I can drill out room for Mid/Bass knobs. I'll screw it into the inside base of the head unit so they stay together.
Heads up about the FMMB fiberboard. Check for voltage leaking across the waxy surface. I think after 1972, fender went overheard spraying the fiberboard with wax. Over time it gets contaminated and begins to conduct. Acetone and naptha can wipe off some excess wax if you find voltage on the board.
I liked all the suggestions in this video. I noticed that the input jack wiring was overlooked in forums but is an obvious place to increase gain. Adding a fuse holder is a great safety feature. Add a reverb and tremolo pedal and you're there already!
The use of an interstage transformer in lieu of a PI (as Gibson did in several amps in the '60s) was an effective cost saving device, but in that, it also could sound very good. Had budgetary constraints not ruled the day here, and another pre-amp tube added (along with more tone controls), this might well have been a great platform for a budget line of amps..but that possibility was lost many years ago...
Yet… these little sleepers can sound pretty good!!
Nice mods for this little amp. The price has gone up for these over the past few years. I have a Bantam Bass amp and I removed the rectangle Yamaha speaker and replaced it with 4-10's. After a cap job, the Bantam Bass really sings.
I've got One with the sane mods but with a 50's Jensen alnico...pure Heaven!
I did the tone stack mod and a Jensen C12N on my 69 Musicmaster and it sounds great. Sweet natural final stage overdrive without blowing your head off.
I hate the stock ‘65 Deluxe Reverb RI Jensen C12K. But in the ‘72 MusicMaster Bass Amp it sounds great. What an overkill at 100W, but it’s destined for repurposing in the ‘72. I put a 3-prong with MOV surge protectors and fuse holder and fast blow 1A fuse for safety.
What a great video. A very late thank you for this.
...if you're the repair shop in AR, those Ibanez pros are sweet...I remember them from back in the day...peace!...
I am..... I really like the Scruggs! Picked up an early Ibanez Byrdland copy that I like better than my real Byrdland!!
I wish this explained what each change was supposed to accomplish sound wise.
good video , it sounds bright
Thanks for describing the mods, and providing a sound demo.
I have a few questions though:
1) Since this is a bass amp, why was it modded into a 5F2 Princeton, and then demoed with a guitar?
2) The clean tone (e.g. 12:33 to 12:54) actually sounds bad to me. It has a rough, random "tremolo-like" quality to it. Could this be due to a faulty tube?
The point of modding this little tube amp is FOR better guitar tone! The arguably best tube guitar amp ever made was a bass amp!
As for the Tremelo like tone you hear… I used a Strat… with a Tremelo…
I would judge the nuances of ANY amp or guitar from a TV, PC or phone speaker!
Thanks for your reply, and clarification 🙂
Although the tweed Fender Bassman did indeed make a great guitar amp, I initially thought that the mods for this amp were done so as to make a better *bass* amp.
When you mentioned "tremolo", were you referring to the "tremolo" (actually vibrato) arm on the Strat, or a tremolo pedal?
Even so, to my ears, whatever the cause, it didn't sound right. Sorry! 🤷🏻♂️🙄
How much do you charge to do these mods? I’m in Columbia SC and have had one sitting for ages. It has a pretty decent speaker and for high gain lead I’m ok with it as I prefer a dark sound, but without the mods it’s terrible for cleans. Thanks for the video!
What is the benefit to changing the values of the filter caps and coupling caps?
Thank you for posting this. Very helpful!
I'm about to tear into my MMB amp. I'm curious -- when you are replacing the caps and such, is it best practice to remove the fiber board / circuit board? Or do you make the changes with the board left in place?
Thanks in advance.
Yeah, absolutely leave it in place!!
Thank you for that excellent video!! I have one question: that radial cap, still 20uf 300V?
Clément Robitaille actually used a 20uf/450vdc, I believe!
Ok thanks a lot!! :D
I did your mods based on this video, and the only problem I had, that I can't solve, is that after adding the 1M ohm resistor, one channel has great volume and the tone control is very good, but the other channel has a much weaker volume. I've checked and wired and rewired but no luck, regardless of the jack I install the resistor on. Any suggestions? Thanks.
As a Musicmaster is a single channel amp, I’m guessing your problem is with the second input, which is wired for a slightly weaker out put from the factory. The 1 meg resistor in the #1 input prevents signal from shunting to ground. Without one in #2, some signal does, hence less volume.
very interesting
any way to get more than 12w out of it - i mean your princeton would be pushing 16-18w right ?
and is that a 12 inch speaker - would it be possible to fit 2 x 10 inches
do you know what years the musicmaster had the tube rectifiers? I learned that at some point they used ss rectifiers, but before that they had a tube rectifier.
I like my FMMBA it is just like this one but with the really good Eminence. NO MODS FOR ME.
I mention the speaker change as being the single best thing you can do!
Thanks for watching and your comment!
@@recycledsound I like amplifier mods but right now I use it also with effects pedals. Having a really good, strong efficient speaker made 1000 percent difference in my amplifier. I put some good quality Tubes into this GEM and it also make a great difference.
I’m curious why the Princeton schematic and your Musicmaster used linear pots on the volume.
jonathan horne good question! Apparently some engineer didn’t like the audio taper curve or purchasing got a deal on them???
I’ve never opened up a Musicmaste amp. The interstage transformer always intrigued me. Enough so that I may build one some day. My blackface Princeton Has analog pots from the factory.
after the mods does using this to amplify bass make it sound thin or different?
Does using a 20uf and 30uf as opposed to two 20uf caps make an improvement in tone?
No
I just bought one of these! Can you advise why you removed the original Fender speaker?
Matt Kerwin Changing the speaker is the single BEST and easiest change you can make to this great little amp!
@@recycledsound Do you prefer a Eminence 50w or so speaker or anything else you can specifically recommend? Thanks!
i imagine it was voiced for bass ? also i think that speakers that came with budget fenders from the 80s were pretty poor so maybe the late 70s too.. i suppose the classic fender guitar speaker is a jensen
Not sure what makes these amps so great if they have to be so heavily modified. It would have been a valuable video had you recorded the sound before the mods.
David Head Guitarist these things actually sound pretty good PRE mod....
just got done with one of these, had some fuzz on the output waveform which we fixed>
groupdiy.com/index.php?topic=71824.msg911699#msg911699
My MMB has a push-pull on off volume pot. Did you change this to and on off switch? I'd like to change my volume pot to 1meg, but it has the on off switch mounted to it and no chassis holes for an on off switch.
1 meg pots with an on/off switch ARE generally available. A Google search should turn one up for you pretty easily.
Well, its actually a turn clockwise to 'click on' pot and there is nothing out there like that. I wanted to somehow change the guts of the existing pot with a 1 meg and re-assemble it but the old original pot/switch cant be dis-assembled.
Bill Kasper are you sure! I've used them many times!
As you can see in vid, our example has a separate power switch.
If you can't find a switch pot, you can easily add a power switch to the rear of the chassis. Drilling a hole there won't hurt anything and I doubt seriously it would have any impact on value. Just keep it as close as you can to same area as where the power cord comes in.
Yes, its an older 6aq5 model with the turn to click pot. I might just put an on off switch on the rear panel.Good Idea!