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Guitar Answered

Well all of you welcome to my little group, heres our first topic, Should there be an instructible about how to create an amplifier? I think so because they are always expensive to buy, to build one though would be fun as well as useful, now you tell me and everyone else your opinion.


how much would a tube for an amp cost?

Tube costs vary wildly. There are generally three classes of tubes in guitar amps: rectifier, preamp and power tubes.

Rectifiers are fairly common, and not super expensive ($15.) Some modern amps forgo the tube rectifier, as the most common audio effect of a tube version is "sag," which can be simulated easily.

Both the preamp and power tubes are absolutely necessary for that sound. Nearly all modern amps use the 12AX7 dual-triode tube for preamps. A 12AX7 could run as little as $10 for currently-manufactured Chinese or Russian version, or if you're a crazy audiophile, over $1000 for a pair of NOS tubes (NOS, or New Old Stock is always more expensive.)

Power tubes usually run $15-20 per tube, but "matched pair" power tubes will be more expensive (per tube.) Matched pair tubes have very similar characteristics, which is helpful when setting a fixed bias. Again, for NOS tubes you may pay far more.

Since the number of tubes in an amp varies (# of preamp stages, reverb, tremolo, etc.) a single cost amount can't really be given....

I find the majority (possibly all?) of the tutorials/schematics/How-To's are for tube amps. I would like to be able to make a non-tube amp, but I'm hard pressed for finding what types of speakers guitar amps use (I would guess a Bass guitar would use a sub woofer, but what about electric guitars?). Point is: We need instructables on guitar amps (non-tube). At the moment, I'm just going to look at the circuitry of my current amp and remake that lol.

I know Celestion high-fi speakers are popular made-for-guitar-amp speakers. I suppose they're just normal speakers, but the resistance can vary. 8 ohm is common for both dedicated amp speakers and home stereo speakers. When I wanted to build a permantent cabinet to put my second-hand head unit in, I used a 12-inch 8 ohm speaker from my high-fi set, and it worked just fine.

If you search instructables for "amplifier", you'll find many more solid-state projects than tube amps. Not all are guitar-specific, but almost all could be used, or modified for guitar.

"Make" had a 386 audio IC practice amp recently, and the Little Gem and Ruby amps are very common, and easy to build. The 386 audio chip is a very easy to find part...

More info?

BGmicro's audio IC page, and the PDF datasheet for one of those chips. Because you can use these cheapo ICs, solid-state amps are extremely easy to build and much, much less expensive than tube projects. The basic schematic is in the PDF, just waiting for someone (such as yourself) to build it....

Of course, when you're done, you've got a SS amp, not usually prized for their tone :-( But it's a matter of taste. I'd like to see more FX stompboxes, myself...

Also you don't see much modding of SS amps--they are almost always PCB designs, where tube amps are point-to-point, or "turret board" -- very easy to modify. Doesn't mean you can't mod SS (go for it!)

Re: guitar amp speakers, search for "jensen MOD" or "weber speakers" to find some decent and relatively inexpensive speakers (yeah, they are different than stereo speakers, and actively contribute to the "guitar sound...")

Their are plenty of documents on the web explaining how to build amps. their are also a plethora of documents lying around, almost always with a detailed schematic. Someone should make a instructable! I might make one in the new year, but i just bought a nice Vox valvetronix, so i am not in need of one quite yet. I beg someone who wants to build a nice 120 Watt, Tube, with lots of effects to do so My idea is to build a nice tube amp, and just run a big effects pedal/preamp to make the effects. Making digital effects on board needs a lot of microporcessor experience and no offesne to any one, but i highly doubt any one person is smart enough and rich enough to afford to do that. So thats my two bits BTW go onto google and search "Little gem amp" you'll get a page that outlines some amps with .5 to 3 watt range. They use simple 386 Chip (From memory) THe larger ones use them in parrel, so yea, its definitly do able. I'm currently having my pieces shipped in for building the original .5 amp lil gem. I'll post a instructable.

How to build an amp? Great idea! This would be good for me because My band can't play unless we all have proper equipment and if an expensive amp breaks...Then pull out frankenamp!


10 years ago

Sure! (ref: Kiteman's Law)

Make had a nice LM386 cracker-box amp recently (I can't find the link.) Here's a similar one, the Ruby amp.

If you're thinking tube amp, there are several instructables for those, also. But I wouldn't recommend tube projects for the inexperienced...

> chokes on coffee <

Kiteman's Law??

I have said it before, and I shall doubtless say it again...

Good grief!

No hypothesis, no theory, it went straight to physical law :-)

Kiteman's First Law, perhaps?

Hehe. It was referenced by the link so often lately, a proper name was needed.

... good ... grief ...

I'm doooomed!

Kiteman's Second Law:
Always use gewd proper grammar and spelling.

(This one's a Law like... no killing people. Its not like the Law of Falling Things Gravity)

Ach, all I need is a Third Law and I'll be like Sainted Isaac...

. OK. St. Kiteman's Law it is. Anything else to say? ROFL

...reaches for convenient sharp things...

But there are none around. St. Kiteman's second law ;-)

Oh wait, you already have two. This can be third then. OR: Always give in to urges to build things at 2am.

... sheesh ...

If you, Nacho and Zach ever end up in the same room, we may all live to regret it...

I think it's time this thread got back on topic. Somebody should say something about guitars or amps.

Unless you'd like to join "Thread Hijackers United Group"? You work out the acronym ;-)

Kiteman wanders off, shaking his head in resignation...

By the way -- I re-ordered the law based on the 3 4 laws of thermodynamics. The first law is now the Zeroth, and the second one is now the Thrid.

And Kiteman -- you should know, talking like this hides it from the admin's eyes (see T3h_Muffinator's logs)
So do one, or the other!

For every action, there is an equal and opposite reaction. Spell poorly, Kiteman corrects it ;-)

Apparently -- you missed my rambling on the other thread >_>

And those are the laws of motion -- I'm talking about the ones of Thermodynamics. (The first law of thermodynamics is do not talk about thermodynamics is not a real law of thermodynamics)

That law that you described of his is his Third law.

I have to check this thread with my eyes closed. Can I open them yet? Has the horrible dream gone away?

Wow, you're good at typing with your eyes closed! I usually make a lot of typos... Acutallly, I just did that and this with my eyes closed, and I didn't make... any! Heh... my backspace key is smoother than my enter key :P (That means it has had more use) All we need is your First law, and then we can write essays on you!

Fingers in my ears, I can't hear you, lalalalalalala!

Hmm, guitar tips eh? How about: never strike your guitar against anything that is harder then a balloon or softer then butter ?

Never eat guitars. They may look nice, but they don't taste very good.

Never pronounce 'guitar' as geee-taar' in mixed company...

Okay, now that Kiteman has let his guard down -- KITEMAN LAWS: 0 - You will exchange information with instructables until the knowledge of both is equal 1 - Don't talk about Kiteman's Laws. 2 - The effects of denounced spammers on Instructables will increase over time, approaching maximum value when they are completely denounced. 3 - As the apparent meaning of a post approaches zero, the lack of meaning approaches infinity All based on the laws of thermodynamics. The first law is based on the ~~fake~~ real first law, which is "Never talk about Thermodyanmics" -- since it fit better than anything I could think up for the real one.

Is this entire topic not in violation of rule 1 then? Does that not make us all hypocrites? OH MY GOD! *BOOM*

We never said we'd follow them, its just... thats the laws :P

As in, far over on the page? Yeah Its fun to scroll down quickly -- its like a logramithic curve. If all our post lengths were the same, it'd be a perfect one -- but some are longer than others. The bump in the curve is when Kiteman says "Kiteman wanders off, shaking his head in resignation..." -- its shorter than it should have been.

Tis not the day after the 31st of Oct yet LOL

Um, that is like a sublaw to the first one.

This is as good a third law as any: I think it's time this thread got back on topic.

. I stole it from gmoon. From this very thread, no less. He gets the credit, not I.

Nice use of internal documentation (I recently learned all about it for my research paper in English class)