Basic Simple 50 watt Bass Head

[big_teee]

I want to build a basic 50 watt no frills bass head.
Something lean and mean with a Pair of 6L6 tubes.
What would you build?
How many preamp tubes, how many Pot Controls, are really needed for bass?
I want to build in Good strong simple tone?
Discuss away!
T

[Chuck H]

Do you want to build a known design or are you planning to design something from scratch? If you're going with a known design the control compliment isn't an issue because any amp you choose sounds good for it's own reasons just the way it's designed. The notorious Ampeg B15n comes to mind. Always a favorite when big power isn't needed and loved by many.

If your going to design this amp some considerations would be:

Over rated PT capability. Sag can be induced with resistance if you want that, but if you want dynamics the power supply can't be choking.

High-ish plate volts.

Big filters and low-ish resistances in the HV rail.

Choke fed screens.

Plan to use a little more NFB than you would for a guitar amp. Bias a little cooler and have lots of clean swing on the PI. It also helps to have a lower output impedance on the PI. A pair of cathode followers could be possible without a real high tube count since the preamp probably won't have a lot of stages.

I'd include a "deep" switch and a high cut control that work at either end of the tone stacks range as well as a mid cut control on a T filter that affects a center point other than that of the tone stack. I might even have it on a rotary switch with four options. (off or any of three voicings).

Tube compliment not withstanding it might be nice to have an effects loop.

JM2C

[loudthud]

The biggest decision to be made is if you want an Ampeg or Fender type tone stack. With the Fender you are limited to scooped mids. With the Ampeg you can add an inductor type mid control but it gets more complicated.

[olddawg]

Unless it is a labor of love, I would suggest checking out the new Fender Rumble 60 watt combo units just for the hell of of it. You might decide you don't need to go to the trouble and expense of building an amp for low volume gigs. Weighs very little, takes up less room, and sounds good.

[big_teee]

Unless it is a labor of love, I would suggest checking out the new Fender Rumble 60 watt combo units just for the hell of of it. You might decide you don't need to go to the trouble and expense of building an amp for low volume gigs. Weighs very little, takes up less room, and sounds good.

It is a labor of Love!
I Like to build my own Amps and Pickups, but thanks for the rumble idea.
I may just build up a 1986 circuit for bass.
Please Keep discussing it and thanks for the ideas.
This will sit in the shop next to the 2204.
Want something rigged up to test bass junk that sounds pretty good, and it must have tubes, and no PCB!
T

[Justin Thomas]

Going on "basic... no frills... lean... mean... pair of 6L6 tubes," I still thnk it's really hard to go wrong with a Bassman head... Love the late BF & SF ones especially! AB165 & later, if only because the channels are in phase & can be jumpered. Either 3 or 4 12AX7s (depending on channels) & 2x6L6. Tube recto optional. I know people deride them, but it's hard to beat as a guitar and/or bass amp for certain things. Hell, just do a single channel if you wanna K.I.S.S. Volume, Treble, Bass. That's all you need. It won't do everything, but it's damn good at what it does - small-gig/low volume bass, loud gritty bass, & loud crunchy guitar. I just find them to be a very good utilitarian amp. Does not play well with new-fangled uber-high-power bass speakers. My AB165 also has great sound for lap steel (I use a modified Lead II w. a P-90 & a Seth Lover). We've put a Dobro through it, mandolin, vocals, everything sounded good through an old Feder cab.

One warning - they have a LOT of bass - great for jazz guitar, not so great for loud guitar or bass - tweak caps in one or both channels to taste. Control pretty useless above 3.

Never tried an Ampeg SB-12... one channel, VTB. How close to B-15 is it? Put it throuh a bigger power section?

I'd say good luck, but I know you'll get a kickass amp built.

Justin

[big_teee]

Going on "basic... no frills... lean... mean... pair of 6L6 tubes," I still thnk it's really hard to go wrong with a Bassman head... Love the late BF & SF ones especially! AB165 & later, if only because the channels are in phase & can be jumpered. Either 3 or 4 12AX7s (depending on channels) & 2x6L6. Tube recto optional. I know people deride them, but it's hard to beat as a guitar and/or bass amp for certain things. Hell, just do a single channel if you wanna K.I.S.S. Volume, Treble, Bass. That's all you need. It won't do everything, but it's damn good at what it does - small-gig/low volume bass, loud gritty bass, & loud crunchy guitar. I just find them to be a very good utilitarian amp. Does not play well with new-fangled uber-high-power bass speakers. My AB165 also has great sound for lap steel (I use a modified Lead II w. a P-90 & a Seth Lover). We've put a Dobro through it, mandolin, vocals, everything sounded good through an old Feder cab.

One warning - they have a LOT of bass - great for jazz guitar, not so great for loud guitar or bass - tweak caps in one or both channels to taste. Control pretty useless above 3.

Never tried an Ampeg SB-12... one channel, VTB. How close to B-15 is it? Put it throuh a bigger power section?

I'd say good luck, but I know you'll get a kickass amp built.

Justin

I thought bassman's were basically guitar amps.
I'm just wanting to build a single chanel basic bare bones amp for Bass.
Have guitar amps.
Going to make a dedicated bass speaker cab for it too.
mojo has a basic 50 watt bass head for not too much, but don't know what is in it.
They don't list a schematic for it.
Enjoying the discussion anyway!
T

[Jazz P Bass]

The left hand side of a Bassman amp Is tailored for the bass guitar.

[Justin Thomas]

Yup. The tweeds might not be so great, but the heads sure are. I think either channel can work, depending on what you're looking for. I was just throwing it out as a stupid-simple effective tone machine. If you get a chance, try one out - you might be surprised. And isn't that 1986 just a twiddled tweed Bassman anyway?

Justin

[big_teee]

Ok, so sounds like take my pick between the various fender or ampeg circuit.
I am familiar with the tweed, marshall layout.
So I will look more at the blackface and ampeg circuit.
Or I may stay with what I'm familiar with.
I have the 87 sitting there but didn't really want to tear it up.
It's all modded out for gain.
I was mainly wanting to talk about what min. tone controls I could get by with.
But, I guess I can go back and look at all the fender tweed stuff with 2 and 3 knobs.
Thought maybe someone had been down this minimum road before.

[Justin Thomas]

What sound are you going for here? Are we talking Geddy Lee or Roger Waters? Admittedly, a Bassman won't do Nu-Metal on a five string... But any of the classic Ampegs and Fenders will do fat vintage and round for days. I just think the Fenders are the simplest of the lot, especially if you do one channel... The 15W head I made for my friend has twice as many fuses as knobs... I guess that's as minimalist as I've seen it.

Justin

[Jazz P Bass]

It also depends on what you are going to use the amp for.

A 50 watt bass amp is going to find it tough to keep up with a heavy drummer.

You need umph behind a bass signal.

[soundguruman]

The basic simple bass amp is the Fender Bassman.
There has never been a more popular or reliable design.

BUT a 50 watt is not usually enough power for modern music.
You will get too much distortion, when competing with drums and guitars.

Bass Amp: at least 3 times the power of the guitar amp, to keep it clean.
Preferably, 10 times the power.

[big_teee]

It will probably never leave my shop, and I'm going to use it to test basses and bass Pickup Junk I work on.
No Drummer.
Thanks guys I'll look and think it over.

[soundguruman]

Line 6 with headphones...