Fender Bassman 100, dating and stuff.

[trobbins]

Perhaps disconnecting the output feedback, and putting a resistor in parallel across the master volume to compensate or even dumb down the total gain so its easier to play cranked.

[Leo_Gnardo]

Thanks. Is there any way I could view your schematic on that presence wiring? I don't really understand how to do the presence-control wiring. Reversing the pot legs and using it "upside-down" is no problem for me. Seems like a good idea to use a pot as slope R as I don't know yet what value sounds good to my ears.

Add-a-presence:

[sibo]

Hi again guys, sorry for some unintentional inactivity. Life basically caught up on me . I just now saw those schematics and I'll definitely use them. However I just found myself in a position where I am not sure whether I should use them on this amp or go with a given deal, and then use them. This guy wants to trade me his ´66 blackface 50W bassman. He's a bass player and wants a more clean sound, that's why he wants the 100W one. What do you guys think? Does anyone have experience with how those amps compare (Bassman silverface 100W 70s vs 50W blackface)? How much volume will I be missing out on through my 8 Ohm cab? How will the sound be affected? Sadly I don't know what schematic it has until tomorrow, earliest.

Also, I noticed there is no master volume nor middle pot on that model. That can't be too hard to add, now can it?

On a side note I am now studying electrical engineering so I intend to pay back some help whenever I am able to!

[Chuck H]

I'd do it. The 50W bf Bassman head isn't really a collectable but IMHO they sound great. It's still not a grinder, but a clean amp that will nudge into some bluesy overdrive. Still... A good clean amp IS a good distortion amp with the right pedal! And the 50W rating makes some power amp compression more accessible. I think there are two things to consider...

Does either amp need tubes or any other work like a recap??? This is pretty important because it can significantly affect the actual, rather than perceived value of either amp. And...

If your willing to part with your amp why not finagle by sale or trade for something that does just what you want? Something like a mid era Mesa combo would do the sound your after very well (ask Carlos). They're reasonably priced and not hard to find. I'm not a big fan but that doesn't matter. Figure out what your price range is (your amps value plus whatever you think you could add) and then check out some used amps in that price range. If the bf Bassman still seems like your best option then go for it. And...

That bf Bassman can pretty much be turned into a mesa type amp without any really tricky mods. But that would mean hacking up a pseudo vintage amp. Your call.

[The Dude]

If your willing to part with your amp why not finagle by sale or trade for something that does just what you want? Something like a mid era Mesa combo would do the sound your after very well (ask Carlos). They're reasonably priced and not hard to find. I'm not a big fan but that doesn't matter. Figure out what your price range is (your amps value plus whatever you think you could add) and then check out some used amps in that price range.

+1 on that. I'm not a fan of hacking up perfectly good amps. There's someone out there who wants that Bassman for exactly what it is and will pay for it. Why not, as Chuck and others have said, pass it on and just look for the amp and tone you want? Of course, it is your amp and your choice.

[Chuck H]

pass it on and just look for the amp and tone you want?

True! But to be fair, even that is relative. Most of us here end up at least tweaking our amps a little anyway

[The Dude]

For the veteran tech, this is not such a big deal. My dislike of mods probably comes from having "un-modded" so many amps that have been severely bastardized. There seems to be a tendency these days to just randomly and automatically throw every mod you can find on the web at an amp regardless of whether it achieves the users tonal goal or not. And then to top it off, most of the mod work I see is horrible- often so poorly done that the resultant tone is worse rather than better. It's not uncommon to see incorrect resistor values (brown-black-whatever is close enough, right?), sloppy solder either not making an electrical connection at all or bridged where it shouldn't be, etc., etc.

I can understand slight mods to tweak in a tone, but I get questions like, "Can you make my Bandmaster sound like a JCM800?". Why? If you're looking for Marshall tone, buy a Marshall. It just doesn't make a lot of sense to me. I got in a Quad Reverb a while back that was so screwed up and had so many mods that nothing even worked right. I ended up borrowing a friend's Quad (no layout available) and just went left to right rebuilding it almost from scratch checking and double checking everything. The guy who bought it wasn't told about the extensive modification, wanted it original, and was willing to pay.

[Chuck H]

I hear you. I think in the case of a bf Bassman head you could do a channel stack mod and add a master volume WITHOUT drilling extra holes or creating difficult to reverse circuits. That amp would take easily to those mods and be pretty much exactly what the OP is after otherwise I wouldn't have mentioned it. But I do hear you.

[The Dude]

There's nothing wrong with mentioning it. For many it's a viable option. It's just my own personal preference to avoid mods. That doesn't make me right.

On a side note, and not speaking specifically about the amp in this thread, a lot can be done by simply changing speakers and/or pickups. Need more gain? Install hotter pickups. Want more of a power amp distortion sound? Use a speaker that breaks up easier.........and so on......

[Justin Thomas]

Hey Sibo, Chuck, and Dude,

Can I jump in? I own a 67 Bassman and a 74 100. Assuming the 50W is in good shape electrically, I'd trade straight up rigjt now! Let your bass player friend have the 100 and if you don't like the BF, sell it to buy something that meets your needs. The volume difference isn't very big, but the 100 is definitely cleaner longer, because it's not the same design as the 50W. I consider 50W Bassmans a secret weapon and would like to collect as many as I can play. I love them, especially the AB165 and later, till whenever. I've never played a Bassman 70, so I'll just say up til then. I love these amps, there's a guy in my town who loves them, they're still relatively cheap, and the ones from AB165 onward can have the channels bridged with no extra mods. This can make for some super-fat sounds, amd can be great for lap steel. That shared "gain" stage makes a lot of difference between the two amps. I love my 100 too, but more for the custom artwork my friend did on the faceplate amd the time I have in it learning. Id seriously have to think about an even trade for another BF Bassman, though. I'd just take the faceplate off, get a replacement, and hand the amp over. Try the BF out - you may fall in love. Should start crunching around 4 or 5 on the volume knobs. No headroom to speak of here, folks...

I'm not going to tell you what to do with your own amps, but a Fender BF ANYTHING that is in reasonable factory condition, love it or leave it.

One note about Fenders - they can fart pretty bad when you crank the bass up. Some like it,most don't. I'm in the middle. Start with the bass on zero and turn it up slowly. And I have a different definition of deafening than most. But if you want to get juicy tone in your bedroom or apartment, this is NOT the amp for you!

Chuck, I'm curious. When you say "channel stack," do you mean kind of run them one into the other sequentially so you've got four gain stages in a row, or do you mean just plug in the patch cable from #2 input into #1 input of the other channel? I just use the patch cable. Doesn't add any real "gain," but does make for an uber-fat sound for jazz and the like. I'm happy with what I've got, and am not looking to change mine. I was just wondering if we mean the same thing.

Dude, I came across a Bassman 50 w. Master Volume that someone had "Marhallized." A nice painful restoration to stock on my part made it a Holy Cow! amp. To this day, it's the only time someone ever said, I always hear your bass, but this time I <HEARD> your bass. My Bassman 100's cabinet is held together woth roofing nails and someone had scraped the "B" off the faceplate and it was pretty gouged up. So I had a friend paint it and now it's the Spaceman 1000. Electrically it's prettymuch stock. I'm with you - unless someone's already trahed it, a vintage amp is a love-it-or-leave-it deal. And as I get to play more, I even appreciate the "crappy" cheap tube amps (Silvertone, Dano, all of those ones, not the modern cheap tube amps) for what they are - soulful grind machines.

Justin

[olddawg]

My suggestion would be go into any big music store and play through a 5, 15, and 30 watt amp. Play something like an Epiphone Valve Jr, a Vox AC 4, a Fender Deluxe Reverb, etc. You will probably be surprised that you need less than 30 watts and can crank and push the amp. Also do not discount checking out some SS amps. I was pleasantly surprised with a Fender Frontman the other day. Not my favorite amp by any means, but very usable and very inexpensive.

[Chuck H]

I mean actually running the triode of one channel as the input to the other. That's pretty much Mesa origins and on an amp as sweet as the bf Bassman heads are it should make for a tone rivaling any Dumble for smooth gain with definition!!! I'm glad to have a backer on this because I've played through a few of those heads and they always surprise me. They all seemed to have that elusive quality of "grabbing the note" with all of the best bf "bell like" tone still intact. I'm not one to invest in vintage amps but I still regret passing on one of these. In fact, early in my growth as a guitar player it was another guitarists '66 bf Bassman head I played through that convinced me I needed to start looking into tube amps!

[sibo]

Thanks again for all of your insightful thoughts.

First of all, I love the sound of my main guitar, I recently did a big research and changed electronics and pups so nothing is gonna get changed there any time soon.
Cabinet - I got this used cheap Laney cab from a friend, it's got 4 12" Celestion rocket 50s. Those being the cheaper model they are meant to be changed once I get the dough for it. Considered substitutes right now are Celestion V30 and Greenbacks. I might even try and mix them. But like I said, that's going to happen down the road.

As of the going for a modern amp approach, I don't think I will. I really like tinkering with old stuff plus I've gotten used to the Fender sound now, I don't want to part with it. Going through a boost pedal and analog RE201 space echo into that sexy amp is just chills all the way down my back
That being said, of course there are things I'd like to add to suite my taste such as for example the previously discussed presence control mod.

Now, about this bf amp, turns out it's a 65(rubber stamp on tube chart says OI). I didn't try it yet and don't know what circuit it's got. Can you tell from the tube chart on that model? How do they compare sound wise? Most seem to like the AB165? There is some "direct current buzz" coming from the bass channel according to the current owner. He had it at a repair shop for 3 months and they still were unable to fix it.. Don't know what that's all about. Anyways, he's gonna cover the cost of fixing that.

To Justin Thomas, I know exactly what you mean about the bass. At first I bridged it and used the bass only from bass channel to try and get it to sound better. Lately I've just left the bass on like 2 or 3 only using normal channel. Also the thought is not to run it in my bedroom, although that would be fun!
I'm not into "Marshalling" it. Even though Marshall sound origins from Fender from what I hear, those fancy Marshall stacks never appealed to me.

I am so psyched to try it. Be back when I have..

[sibo]

So once again I am back!
That deal with the BF is now officially off (after over 4 months of back and forth with repair shops involved) ..so I intend to proceed with the mods on my Bassman 100 SF. This time also helped me decide to start off with the "marshalling" tone stack mod and mid pot, reworking the bass channel. At least for starters. Presence is next up I think. Is the marshall mod LeoGnardo describes the so much discussed "plexi-mod"? I will try to edit the original schematic just to show you how I think it should be wired up. Any advice on software for that particular task? It's been quite a while since this thread started so I have no intention of rushing anything, I'd rather do it once and do it the right way - taking all the boring steps.

[gui_tarzan]

It's nice to know my '73 SF Bassman 100 will be LOUD when I put it back together. I play bass in our band (and occasionally guitar on the side) and need the oomph. My intent is to refurb it and make it work and look like new again, then try it at gigs and see how it performs. The fiber boards were warped beyond usability so I'm going to rebuild them using PCB and eyelets. If it doesn't compare with my Ampeg I'll probably put it up for sale and use the proceeds to put together something low-watt for blues style guitar.