Bass tube amp

[bassmasta17]

has anyone built one before. Me and my dad are considering making one with cabs. The cabs will be 1X18 and a 15 or 12 with a horn. i play thumb style but also alot of effects, play finger and pick style. I just need something loud and has a lot of bottom end. Any thing that will go along well with my
funk

[Ben N]

There are basically 3 things that make a generic amp a bass amp: power, eq and speaker/cabinet.  The amp design itself is not fundamentally different than any other amp.

Bass takes a lot of power--if you are playing out, don't think about less than a quartet of 6L6s or EL34s (or some scheme to get a lot of extra power out of a pair, such as the UL Bassman 70, various Musicmans or the Traynor Bassmaster Mark II). This is a pretty big project, especially if it is your first tube amp. It is also costly. You may want to consider buying something used and modifying it--you will save yourself a lot of grief and probably save $$.

Pretty much any amp that has the juice to drive your speakers without distortion can be tweaked for bass, as long as you have the right cab, by lowering low frequency cut offs (bigger coupling caps, cathode caps, phase inverter input networks) and adjusting eq ranges. This is pretty much a matter of tweaking values rather than changing designs.

[Ben N]

I should add that one thing a bass amp needs over a similarly rated guitar amp is big (and expensive) transformers. Take a look at pics of the transformers of a 50 watt Bassman versus similar 50 watt guitar amps, like a Bandmaster to get an idea.

Again, building a large tube amp from scratch is an expensive, difficult and possibly dangerous proposition if yu don't have some knowledge and experience at it. It is not comparable to building a Rangemaster or Tube Screamer, or even an Electric Mistress. Most amp builders start small and gradually work their way up. There are used amps out there (tube, SS and hybrid) that will fit your bill, and others that can be modified. I bought a working Music Man 65 Bass for $200 a little while back, and Traynor YBA-1As can be had for ~$300. To do it yourself, you'd probably spend that much on a cabinet, chassis, transformers and a circuit board, not to speak of tubes, sockets, diodes, resistors, caps, pots, jacks, switches and wire, and you would still be many hours away from a working amp. Since many of those amps are hand wired, they are easy to do maintenance on and modify, as you need or want.

[ItZaLLgOOd]

I spent around $350 on a simple 9 watt guitar tube amp from AX84.com.  If money isn't the issue and you guys like a challenge it sounds like a fun project.  I learned a lot when I did mine.  Definitely read up on the SERIOUS hazards that go along with high voltage tubes.  Be safe and have fun.

[Ben N]

John, would you agree that something like your 9 watt AX84 (relatively simple, with lots of resources and support available) makes a better place to start building amps than a 60-100 watt class AB fixed bias monster?

Maybe I am assuming too much about the OP--that his folks are new to this--but that is the impression I got from the post. If I am wrong, I apologize.

[ItZaLLgOOd]

Absolutely.  Projects as big as tube amps (even little ones) require a lot of different skills to be successful. They make it very easy to get good results over there at AX84. Maybe there is site for bass amps, not sure, but it would help greatly.

[drewl]

Check out the kits from Weber.
They offer a Sunn clone, orange and I believe Hiwatt. Any of those should be enough power for most gigs.

[runmikeyrun]

yeah man you're looking at a huge undertaking.  I second modifying an existing amp- i bought a peavey windsor new for $400 and just changed some coupling cap values in the preamp and PI.  Sounds a lot better.  Would probably sound even better than it does now with some JJ EL34Ls but i don't have the $75 for a quartet.  You could probably get a used Windsor for a good price, and it's basically a hot rodded 100w JCM 800 so it's a good foundation.  I suggest trying one first in the store, if you play funk, it might break up too much for you. 

Even better might be buying a peavey VB-2- $849 for a 225w all tube bass head.  If i get that kind of money i know where it will probably go

[8mileshigh]

I think you should try and assemble that simple fuzz circuit before diving blindly into amps.  You need to take baby stepswhen you're learning something new.  Have fun !

Chris

[bassmasta17]

well i have decided to build a tube preamp that will go into a power amp. I think that will be the better decision. Thanks for being so fast... all this in under 24hrs. my fender rumble 100 amp has a pre amp out and a pwr amp in in the fx loop. does that mean power amp? i would not use a power amp in that because i dont know what the handleing is on the woofer. it doesnt make scene.

[Ben N]

Good call on the preamp. There are a lot of good DIY options there. I don't really understand your question on the Fender, though. Maybe you can clarify. If you have a manual or schematic, they may help to determine if the FX loop return feeds into the power amp. They will also give you some ideal of the topology of the power amp to determine if it is bass amp material, although at 100 watts you should be fine as long as your cab is the right impedance.

[doug deeper]

webers s100 (or 100s?) is a great bass amp project!
works great for guitar as well.