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DIY Bass Amp


basey
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I have almost no knowledge of how tube amps work.

But nonetheless I want to try and build one from scratch. :D

I have been looking on line for a kit or step by step instructions (for dummies) but I can't find anything that is even close to the wattage I need (350 - 500)

Does anyone know where I could get plans for a amp like this. It doesn't need a preamp, just a poweramp.

Any help would be greatly appreciated.

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tube amps. hmm

here for marshal diagrams (in the nav bar on the left) as well as tube datasheets and schems for other amps/companies

fender amp fieldguide has lots of schematics as well chasis diagrams and specs/pictures of a lot of fender amps

as well as here for fender amp schems (a lot of them, but not too many bass ones)

and finally here for tube datasheets (tons of them),

maybe you should read up on tubes, i got my basic (very) knowledge of amps and tubes from my grandpa over the summer, also unlike guitar schematics, just wiring plans for amps are rare (most likely non exsistant), since they are all writen in schematic form, so learning to read schematics will help,

Edited by truerussian558
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The biggest problem with answering your request is the power you're looking for - even the old Marshall Major series was only about 200 watts! To get close to the power levels you're asking for, you'd need at least a quad of high-powered tubes (6550s, or maybe KT88s?), or 8-12 standard power tubes like 6L6s or EL34s (Mesa's Bass 400+ uses 12 6L6s). The transformers will be very expensive, and might prove hard to track down - you may even have to have them custom-wound. Might I suggest that you build a 50-100 wat bass amp, and spend the rest of your cash on a couple of kilowatts of solidstate power and a good pair of subwoofers for the PA so you can mike it if you need to? It would be less expensive, and you could actually use the amp in venues smaller than the Grand Canyon without causing internal bleeding. Just my two cents! :D

For an idea of what you're up against, cruise over to Tubefreak's Mesa page, and take a look at the Bass 400 schematic.

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THIS IS MEANT TO BE BIG AND LOUD. TUBE AMPS WILL DO MORE THAN JUST KNOCK THE CRAP OUT OF YOU, ANYTHING MUCH OVER 30MA AND OVER 240 CAN TAKE A DEFIBULATOR TO RESTART YOUR HEART. BE VERY CAREFULL. START SMALL THEN WORK YOUR WAY UP.

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Is there a way of making an amp save. I've heard about people dying from a shock they got from the amp so isnt there some kind of thing you can put between your guitar and the amp that makes sure nothing can happen?

If course you can go wireless but at the moment that costs to much money.

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It would be less expensive, and you could actually use the amp in venues smaller than the Grand Canyon without causing internal bleeding

I'm not sure how different tube amps are from solid state, But I do know that 350 watts is not overkill on a bass amp. It takes a lot more power to get the volume on a bass amp comparable to a guitar amp. It's not unusual for a guitar amp to be 50 to 100 watts. A 300 watt bass amp could not put out half the volume of a 50/50 guitar amp. The idea is to have more power than your going to use, so your signal doesn't clip as much and ruin your tone/ speakers. I use a 450 watt mosfet amp currently with the preamp volume at about half. the signal is always clean and the tone is never compromised. I hope that makes sense. I've learned about this the hard way.( $1200 in blown/ damaged speakers from clipping)

The reason i'd like to build a tube power amp is to get the (warm tones) but I don't want to have any preamp on it at all(svt, mesa)

If the wattage in tube amps works differently, that would be great, but I was not aware that they were.

I think you guys are right though. Maybe its too ambitious of a project.

I probably better leave this one to the pros. :D

Thanks for all the advice, and concern.

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a 50 watt tube amp is roughly as loud as a 100 watt solid state just to give you an idea

what?

i cant see how much of a difference it would make if the power to drive a speaker came from a tube or a transitor unless of course other specifications (besides power) are different., if not please enlighten me

also i would think about going solid state, not only is it quite unusuall to find a 400watt tube bass head, it will be overly expensive (the tubes would be much over $100 and maybe over $200) unless you have tubes scavengeed from some old radio or something. and you will lose the risk of getting hit with lethal voltages.

its a pity my grandpa threw out a crate of old tubes, i could have used them :D

Edited by truerussian558
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Tube amps are NOT louder than Solid State they just distort more and make things sound louder. The issue is: driving a tube amp into distortion sounds nice but driving a solid state into distortion sounds horrible!

For Bass I don't think you would want any distortion so go with a solid state and don't drive it as hard as you would with a tube amp!

Keith

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The transformers will be very expensive, and might prove hard to track down - you may even have to have them custom-wound. Might I suggest that you build a 50-100 wat bass amp, and spend the rest of your cash on a couple of kilowatts of solidstate power and a good pair of subwoofers for the PA so you can mike it if you need to? It would be less expensive, and you could actually use the amp in venues smaller than the Grand Canyon without causing internal bleeding. Just my two cents! :D

For an idea of what you're up against, cruise over to Tubefreak's Mesa page, and take a look at the Bass 400 schematic.

There's a bit of a way around that...sort of.

Use a standard preamp section, and from there, split your signal into 2 quads of EL34's.

From there, you can either set each quad into it's own output tranny, and then re-couple the signal on the secondary side, before the output to the speakers...

OR

Wire up the two output trannies in series so that you've literally got a primary and secondary of twice the resistance of a single tranny...

That's my best guess...

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Tube amps are NOT louder than Solid State they just distort more and make things sound louder. The issue is: driving a tube amp into distortion sounds nice but driving a solid state into distortion sounds horrible!

For Bass I don't think you would want any distortion so go with a solid state and don't drive it as hard as you would with a tube amp!

Keith

Yes and no...Tubes are capable of distorting earlier, and in a more linear sense than SS electronics. Further, that distortion is harmonic in nature, which sounds GOOD to our ears, as opposed to the massive clipping that an overdriven SS amp will produce.

Tubes overdrive to produce a very nice, smooth waveform, with slightly flattened peaks and valleys. Solidstate overdrives into a very square wave shape.

Tubes don't really "make" anything sound louder...it just seems that way to our ears, based upon the type of distortion produced.

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I build a 100-watt tube amp over the period of January-June of this year...

Firstly, you should have a decent knowledge of electronics; soldering, reading circuit diagrams, and safety wiring are all essentials here.

Also, I dunno what part of the world you're living in, but you're gonna wanna be a bit careful...if your country runs 220 or whatever volts, be CAREFUL. Nobody's died in North America from a tube amp, as far as I know, but in Jolly ol' England, that might be a different story...I've taken 447 vDC from my amp during the build process, and lemme tell you, it ain't good times!

Also, make sure you've got a good range of tools handy...if you're indeed doing this from scratch, get a good chassis made from aluminum, it's easier to work with! Buy a good bi-metal hole saw set, a couple of step bits, a GOOD solder iron (can't stress this enough!) and get ready for some major squinting! lol

Gimme a shout if you need any more info!

-Kev

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a few things to consider

use an old computer case to make your own chasis as its more work but cheaper that buying and just as sturdy.

i wire up my powersupplies two ways. the first way is on a seperate table with dedicated filter caps and a dedicated diode rectifier and i am working on a tube rectifier. this has a seperate meter that is used for just that purpose only.

i wire it up turn on the meter and walk away from it. then walk to the switch. [when i first got into this i had a remote controled stereo that was broken and i used it to power on and off the circuit via remote control across the room] then i flip the breaker on. from where i stand i can see if it smokes catches fire blows up. burns the meter and what the voltage is if its working properly.

from there it gets completely discharged via a 100watt light bulb that is connected to the capacitors. then it gets completely dismantled and unbolted from the table. then it sits and waits till i hook it to the chasis and wire it to fresh caps and rectifiers. and i plug in the board.

i am now trying to convert over to Molex type connecters. so the 12ax7 type sockets can be replaced quite easily.

the more tools [and the better quality ] the better.

also knowledge about what you are doing is best. start small with cheap low voltage parts. then increase the actuall working voltages.

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use a high voltage neon designed for a flash system.

i have a 1000v one. and i put it on a plastic shaft momentary switch to ground.

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the AA964. i thought of doing the wide faced princeton (5b2 is it?), but it was a bit too simplistic, so i went with the black faced (non reverb) princeton, plus i got the whole push/pull tube workings (of the power section) explained to me by my grandpa (i thinks its called something like working mode b (sorry russian to english translations can get confusing :D ))

also ive decided to call it "stanford" B)

Edited by truerussian558
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An excellent choice! There are some cool mods for sweetening the phase inverter up in that setup for a smoother overdrive, PM me if you want 'em and I'll track them down. There's also a pretty good layout over at Schematicheaven.com, but you probably already have that. Are you going tube rectifier or solid state?

Sorry, didn't mean to hijack the thread, I just love little 6V6 amps - you'll really enjoy it!

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as i am making a fender princeton amp in my electronics class (its electronics 1 and i know msot of the stuff we will be doing), i was wondering what is the best way to discharge the caps quickly after you turn off the amp

1. Screwdriver --> short the capacitors to the ground. Quick, simple, makes for interesting sparks. On the bad side, the capacitors WILL "regrow" some of their voltage...

2. Switch that runs the capacitors directly to the cathode resistor on one of the preamp tubes. This drains the caps off a bit more gently, and is a helluva lot safer. Uses existing resistors, and will require only 2 wires and a switch. Prevents "regrowth" voltage from becoming an issue. Just remember to turn the switch to the "open" position next time before you power up!

-Kev

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as it wont affect the sound, im leaning towards going for a solid state rectifier (2 diodes), as it will give me one less thing that is rediculously over priced

also id love those mods. and i got the schematic from fender field guide.

Um...wouldn't a full-bridge rectifier be 4 diodes??

And if you're replacing an amp's tube rectifier with diodes, keep in mind that the voltages seen after the rectifier WILL be different, sometimes by a large margin!

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