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.

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wazupwiop9 years ago
how much would a tube for an amp cost?
gmoon wazupwiop9 years ago
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....
Treviun9 years ago
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.
Rishnai Treviun9 years ago
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.
gmoon Treviun9 years ago
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...")
mondaymonkey10 years ago
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.
tmd931410 years ago
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!
gmoon10 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...
Kiteman gmoon10 years ago
> chokes on coffee <

Kiteman's Law??
Goodhart Kiteman10 years ago
Nacho's dubbing here: Kiteman';s Law
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