First Build Ideas for amp used for both bass and guitar

[Eulipian]

Looking for ideas/suggestions for a first build that will be used both for bass and guitar.  Was looking at the 5F6A here and the Weber 6S100.  Doug's system and parts seem straightforward to understand and use.  Not sure the Bassman is a good first build candidate, though. I'd appreciate any ideas as to any of the plexi clones or other amps here that might work with or without mods or anyone who's built the 6S100.  Must confess that having Doug's Bassman board pictures gives me more confidence than working from schematic and layout diagram.  However, I want to build something that works and any ideas on other amps would be welcome.  Want to finish this before my son, the bass/guitar player graduates (in two years).  A head might be better than a combo so he can take it with him when he goes to college, but I'm not wedded to any concept (as I have so few).  Thank you for your thoughts.

[triode]

I build and sell an amp that is explicitly a bass and guitar amp... I suppose my only suggestion would be that you have to choose a nice power point and speakers. You want efficient enough speakers on the bass end so that you do not need a 200W unit, and yet you want something that sounds good on the guitar end without killing you with db. I picked 70W, and for bass I drive a single 15" plus a 4x10" cab, for guitar you plug it into a different 15 for jazz or a 2x12 (not the super efficient ones) for everything else.

A note, you may find that something like a plexi50 preamp (or a bassman, pick your poison) on the guitar side and a "cleaner" preamp on the bass side works nicely. I did something similar, but not off the shelf preamp circuits. For the bass side you tend to want clean until later on the volume control... I find a lot of bass players really appreciate a nice breakup, but much later on than guitarists (how many studios use an Ampeg B15N 50W bass, into a JBL D130? A LOT of them, so you don't need 100-200W unless you are doing live. Then again, I have customers that do live gigs with my 70watter).

I am not familiar with the 6S100.  I will tell you this, and I will tell you this twice, and a LOT of people will always disagree with me on this (all the time), but you want a killer output transformer for a bass amp. A "regular" guitar amp will be 3db down under say 60-70hz... 3DB!! That is 1/2 the volume! You want a transformer that will do at LEAST 30hz at FULL POWER. I do 20hz at FULL POWER, as most people do not count all the harmonics that come out of the bass guitar as "real", but it eats power and it eats your bandwidth in the output transformer.
Again, get an output that will do full power way down low, at least 5-10hz under what your bass will put out, and account for things like people drop tuning the bass, or getting more strings later on.

Finally, are you sure you want to tackle a two-preamp amp as a first build? I would strongly suggest sinking some cash into a "practice" amp with one preamp at first, before you go purchasing large irons and large custom power trannies for a bass/guitar amp, but that is just my opinion.

[sluckey]

Long time ago I built an AB763 Twin Reverb but replaced the normal channel with the AA864 bass preamp. It was very useful back in the '70s. I sure would not recommend it for a first build though. Here's my plans for the amp...

http://home.comcast.net/~seluckey/amps/misc/76_Amp_Project.pdf

[Bub]

I can't comment on the technical specs but having done my second build, a 5F6-A, I can say that the simplicity of the layout plus all the documentation that comes with Doug's board does make it a great build.

Best of luck

Rob

[Eulipian]

I am not familiar with the 6S100. 

It's a modeled on the Sunn 100W.  Thanks for your ideas and for the caution on biting off more than I should on a first build.  I'm sure you're right about that and probably should try something more straightforward for a first.  I will reconsider. 

[Eulipian]

Long time ago I built an AB763 Twin Reverb but replaced the normal channel with the AA864 bass preamp. It was very useful back in the '70s. I sure would not recommend it for a first build though. Here's my plans for the amp..

Very cool, Steve, but too intimidating for me at this point.  Next lifetime maybe.

[terminalgs]

A head might be better than a combo so he can take it with him when he goes to college, but I'm not wedded to any concept (as I have so few).  Thank you for your thoughts.

If you are building it for your son,  you should figure out what he'd want in amp. Hhe probably won't have a lot of room for equipment.  will he be in a dorm?  If so, he'll probably have to make due with a single amp, and a combo would probably be better than head/cab.   Build him a small 1x12" combo.  something with a decent tone stack.  an SE 5w might be the trick.  or maybe a 12w push pull if you want.

Start with that,  and leave room in the chassis for another board if you can,,  after the amp is working,  maybe you can add the 1st half of a buffered effects loop with a level control and an 1/4" out or a 1/8" out so he turn can plug it into garageband or something that dorm life might require him to do...