Wanting to build a bass amp from scratch

[mooreamps]

But since I prefer to play loud it works in my favor

Sounds like problem solved to me... Now, what you say we build this guy a smoken bass amp ?

-g

[hasserl]

It's only my opinion, but I think everyone overplays the need for excessive power in bass amps and excessive volume from the bass rig. It's when the bass rig gets cranked up that everyone else has to turn it up to to play over the top of the bass. But I play classic rock and blues, and the bass guitar is 1/2 of the rhythm section. Together with the drums they form the foundation that the solo instruments play on top of. Far too many bassists THINK they need more power, the truth is they need to turn it down a little, because they're TOO FRIGGIN LOUD. I don't know where you all are playing at, but in the bars and small clubs I play at, when you play too loud you antagonize the patrons, and that pisses off the owner, and you'll get your band barred from return engagements. People are tired of going home with the ears ringing. It aint the 60's anymore, and all the baby boomers have been there and done that and now they like the music, but they want it at lower volumes.

I own a Peavey Max 115 bass combo amp that I supply on the backline of the blues jams I host, and it easily keeps up with the 15 watt Blues Jr's or even the 40 watt Hot Rod's or my 5E5A tweed Pro clone or 5E3X2, no problem. And those amps are way more than enough in the hands of a hamfisted player to piss off a bar owner, even the little Blues Jr.

Outdoor stages are a little different, and you can crank it up quite a bit and most of your sound dissipates into the sky, and if you're elevated the amps projection doesn't hit the audience square on, so you can get away with a lot more; or in fact you often need more. But the bass and drums still set the volume floor that everyone else plays on top of. I just don't see the need for all this power. Back it off and save everyone a lot of grief.

[Chuck H]

Sounds like problem solved to me... Now, what you say we build this guy a smoken bass amp ?

-g

I think this thread has devolved into a more general discussion of the issue because the OP only has the three posts on this thread and went MIA on the subject half a year ago.

[mozwell]

I have a hybrid amp that i have used for the last 10 years.
it has the valve pre from a SVT-2, and a solid state power amp.
I am happy to send the pcb files & schematics. If you can get a prototype pcb made for you & drill it yourself, it can work out fairly cheaply.
the hardest thing to fins will be a transformer with a low current 200VAC winding, a 6.3VAC 1A winding & a 15-0-15VAC 0.2A winding. You may be able to to use separate small transformers to get the required secondaries.
The inductor is wound on a RM-8 ungapped ferrite core set, so you will need some very small insulated wire to wind this.
hotmail andymac1962

You can then get a second hand power amp, for any power you want, & a second hand speaker.....

[olddawg]

I do something like that. I'm a guitar player that occasionally plays bass. A while back I picked up a Gorrilla bass amp that was DIA for nothing. I fixed it and upgraded the 10" speaker to a 12" JBL I had laying around. It's great for acoustic sessions. It has a built in compressor an a DI and line out. If I need to play loud with it just run a power amp (another DIA I fixed) and a 2x15 cab I got for $150. I can also DI to the PA if needed. I'm sure it isn't the latest and the greatest, but it is very flexible and cost very little and sound pretty damn good.

[J M Fahey]

Agree.
Although I make some loud amps for Stadium playing customers , which is good because it raises the perceived value of my stuff, the bread and butter amp that keeps me alive, pays the bills, etc. is an SS one, 100W, compressor, 2x12" .
Light and portable, fits most car trunks (worst case the back seat) , and can be used *anywhere*.

It can be easily be shown to be true onstage: it matches perfectly any normal drummer, with a little extra power to spare, and where "it´s not loud enough", such as a bigger stage, then *everybody* needs help from a PA system, not just me.
After a lot of live experiments I settled on 2x12" instead of the classic single 15" which in no way matches their presence and projection.
2x10" sound very good, but are less efficient than 2x12".


EDIT: as usual , I talk too much
In a nutshell, what do I mean after all this rant?
Simply: that even a humble 100W SS bass amp is often more than enough onstage.

[Steve Conner]

Interesting that you settled on 2x12". I've heard this said before, that it's a great speaker choice for bass, but for some reason bassists are prejudiced against 12" speakers. Well, except for Geezer Butler and his Marshall stacks stuffed with EVM12Ls.

I agree on the lower power comments. I've caused surprising amounts of damage/annoyance with a 60W tube amp and a 2x15" cabinet.

Also, that was exactly what I meant, the difference between "just plain loud" and "extremely loud".

[J M Fahey]

In fact, originally I settled on 12" because when I started making my own speakers, the *big* ( as in BIG $$$$) problem is the dies needed to press the speaker frames.
I had to settle on one size to begin with, 12" was chosen because it was the most flexible and cost-efficient solution:
a natural for guitar, they reach high enough so a couple Piezos supply enough highs for PA/Keyboard/Acoustic cabinets, and 2 of them surpass a single 15" cone area.
A real Jack-of-all-trades.
Not as deep bass as what 15" speakers provide, but still reasonable, and careful cabinet tuning makes up for that.
My surprise came when I started running them against 100W, 15" Acoustic 126 amps, the bass amp "Standard" way back then in Argentina (mid 70's), my 2x12" beat them on stage and in rehearsal rooms any day.
Now, almost 40 years later, they regularly beat the typical 1x15" Fender/Laney/Crate/Marshall/Peavey combo.
Fender BXR300 and Peavey Combo (300W) are in another class and not to be compared to these.
Besides , they cost 5X more !!!

And yes, there´s prejudice, whenever I mention 12" speakers everybody screams "Guitar Speakers" !!!!
Oh well.

[mooreamps]

So, if I built up my 813 project as a bass amp, the consensus being it would be too big for most venues ?

-g

[Chuck H]

So, if I built up my 813 project as a bass amp, the consensus being it would be too big for most venues ?

-g

I guess that would depend on how big it is. You didn't say.

And to be sure, what's happening here now is a shared opinion that is contrary to the general concensus. The general consensus is a 400W bass amp.

[Steve Conner]

With the right custom OPT and a 2000V B+, 500W.

With any OPT you can buy off the shelf, you'll be lucky if you get 150W.

JM, do you make your own speaker frames in-house? The press must be huge. Or do you own your own custom dies, but they live at a metal factory. We have a similar arrangement with injection mould tooling.

I know 400W is a sort of consensus, but it eliminates the Ampeg SVT, the B15N, the Marshall Major, all of the Acoustic amps, all of Trace Elliot's tube gear, even the mighty Fender 300PS. I can't think of one classic bass rig that was 400W or over, except maybe the Fender 400PS with three cabinets, but that never really caught on.

[mooreamps]

I guess that would depend on how big it is. You didn't say.

And to be sure, what's happening here now is a shared opinion that is contrary to the general concensus. The general consensus is a 400W bass amp.

No, I did not say.. Currently plate voltage is 1.4 kV ; screens at 750, running combination bias class A/B.

-g

[GregS]

I know 400W is a sort of consensus, but it eliminates the Ampeg SVT, the B15N, the Marshall Major, all of the Acoustic amps, all of Trace Elliot's tube gear, even the mighty Fender 300PS. I can't think of one classic bass rig that was 400W or over, except maybe the Fender 400PS with three cabinets, but that never really caught on.

My guess is there's no need for any more than 300W in any practical situation. The amp itself simply has to provide enough stage volume to act as a monitor. The PA fills the venue however large. I don't know what's required to provide stage volume in a really large venue because I've never played one. I've used a 200W combo bass amp in bar gigs and outdoor parties and have never come close to running out of volume or headroom. I've even managed with my 14W home built amp in some bar gigs and the band wasn't quiet either. When you have a line into the PA it's possible. More wattage than that is certainly better though.

[Bruce / Mission Amps]

I played with a bassist a few months ago who used a little bass amp with two 8" speakers and he says around 75-80 watts... it was killer.
Another time I played with a bass player who had a 100 watt amp with the cabinet elevated about 2-3 inches and the little 10" speaker facing down at the floor!
That was a great sound too... guitar amps were all in the 12-20 watt range.

[mooreamps]

Oh, I suppose I should just cobble up some kind of a preamp for it, just to see what it would sound like.
Besides, I don't like to see it half finished just sitting there in my lab.

-g