Any good simple 12xx7 mini-guitar-amp schematics?
- Thread starter Ethan
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asm
Well-known member
ever seen AX84.com?
got tons of small-er watt stuff over there.
t
got tons of small-er watt stuff over there.
t
It isn't clear from that picture, but the Marshall MS-2 Mini Amp (Musiciansfriend.com Product #482812) is $34.99 and 5.75 inches (14.6cm) tall, about 4 inches/10cm wide. This image is just about life-size:
I have calculators bigger than that!
I don't think it is impossible to put a tube in there... but even just a 12AX7 with speaker transformer and power supply will fill the cute case, and probably melt it.
And from the reviews, it is a damm-fine pocket-amp the way it is.
And its key shortcoming may be its diminutive size, its acoustic projection and balls. You can't change the fact that it is a 3" speaker in a 4" box. A gitar amp should be at least as big as an acoustic guitar body, to be impressive.
I'd have to dig through the boring pages of the tube manual to pick a low-watt 7-pin output tube. You could fit that plus a speaker transformer, but the case would get soft from the heat, and the power supply has to be external (or hot-chassis, but I love you too much to allow that). Adding a preamp tube to bring pickup level to power-tube level would be a real tight fit, and probably make the case sag from heat.
You could keep the existing power-amp, there can't be much wrong with it, and add a hearing-aid tube as the preamp. Still needs external power, though it could be a C-cell and five 9V batts.
As a Very Advanced Project, you could maybe develop a push-pull parallel quad-array of hearing-aid tubes to make nearly the same audio power without an impossible amount of heat. Plus three more tubes for preamp, driver, phase-splitter.
Or were you thinking of putting the tubes on top? That would reduce the heat issues.
I still think the joke isn't worth the effort.
I have calculators bigger than that!
I don't think it is impossible to put a tube in there... but even just a 12AX7 with speaker transformer and power supply will fill the cute case, and probably melt it.
And from the reviews, it is a damm-fine pocket-amp the way it is.
And its key shortcoming may be its diminutive size, its acoustic projection and balls. You can't change the fact that it is a 3" speaker in a 4" box. A gitar amp should be at least as big as an acoustic guitar body, to be impressive.
I'd have to dig through the boring pages of the tube manual to pick a low-watt 7-pin output tube. You could fit that plus a speaker transformer, but the case would get soft from the heat, and the power supply has to be external (or hot-chassis, but I love you too much to allow that). Adding a preamp tube to bring pickup level to power-tube level would be a real tight fit, and probably make the case sag from heat.
You could keep the existing power-amp, there can't be much wrong with it, and add a hearing-aid tube as the preamp. Still needs external power, though it could be a C-cell and five 9V batts.
As a Very Advanced Project, you could maybe develop a push-pull parallel quad-array of hearing-aid tubes to make nearly the same audio power without an impossible amount of heat. Plus three more tubes for preamp, driver, phase-splitter.
Or were you thinking of putting the tubes on top? That would reduce the heat issues.
I still think the joke isn't worth the effort.
ethan-
ax84 is the best low watt guitar site I know of. Im sure you probably want to build something, but if you get the hankering to spend money, check out the zvex nano amp, that thing looks interesting, although Ive never heard one. I use some of his other stuff and its all very well made for what it is. Ive been working on a record for the last couple of months and have used pretty much all low wattage amps and am sitting on the biggest guitar sounds of my life. The badcat minicat is an incredible monster of an amp and its a single ended el84. totally amazing amplifier. had to put in my plug for that one...
dave
ax84 is the best low watt guitar site I know of. Im sure you probably want to build something, but if you get the hankering to spend money, check out the zvex nano amp, that thing looks interesting, although Ive never heard one. I use some of his other stuff and its all very well made for what it is. Ive been working on a record for the last couple of months and have used pretty much all low wattage amps and am sitting on the biggest guitar sounds of my life. The badcat minicat is an incredible monster of an amp and its a single ended el84. totally amazing amplifier. had to put in my plug for that one...
dave
Marik
Well-known member
Ethan,
Check these links. Subminiatures might have right size to fit:
http://www.harmonicappliances.com/powerman/powerman.html
http://www.freewebs.com/amp_build/powerman.htm
http://amps.zugster.net/projects/micro-old/index.html
Check these links. Subminiatures might have right size to fit:
http://www.harmonicappliances.com/powerman/powerman.html
http://www.freewebs.com/amp_build/powerman.htm
http://amps.zugster.net/projects/micro-old/index.html
Probably won't fit in there, but sounds great:
http://home.cfl.rr.com/dbhammond/ff.htm
EDIT: please ignore the links below, i need to test some things and don't want to start a new thread for it.
onepage http://www.groupdiy.com/index.php?topic=26218
xyz blafasel onepage gnarz http://www.groupdiy.com/index.php?topic=5957
onepage http://www.groupdiy.com/index.php?topic=27348 http://www.groupdiy.com/index.php?topic=27811
onepage http://www.groupdiy.com/index.php?topic=28159 onepage http://www.groupdiy.com/index.php?topic=28146
http://home.cfl.rr.com/dbhammond/ff.htm
EDIT: please ignore the links below, i need to test some things and don't want to start a new thread for it.
onepage http://www.groupdiy.com/index.php?topic=26218
xyz blafasel onepage gnarz http://www.groupdiy.com/index.php?topic=5957
onepage http://www.groupdiy.com/index.php?topic=27348 http://www.groupdiy.com/index.php?topic=27811
onepage http://www.groupdiy.com/index.php?topic=28159 onepage http://www.groupdiy.com/index.php?topic=28146
Thanks guys.
Yeah I figured at the least I would have to have the tube hang outside the box, but I didn't even think about the power supply it might require, which would definitely not fit in this thing...
BUT, I think I just might take on a guitar amp project very soon since I have a bunch of preamp tubes and left over Hi V parts. If I could only find a good small combo chassis or maybe just an empty head (other than the one resting on my shoulders, har har :green
BTW PRR, I couldn't find any 1K, 10K or 100K pots, So I think I'm going to rig a switch to try out different resistance values there and see what's going on. Any tips on how to accurately note the ratio relative to the threshold? I know that sounds counterproductive to rig a switch to then find out what kind of pot modification would work, but the strange things I do to try to learn something...
Yeah I figured at the least I would have to have the tube hang outside the box, but I didn't even think about the power supply it might require, which would definitely not fit in this thing...
BUT, I think I just might take on a guitar amp project very soon since I have a bunch of preamp tubes and left over Hi V parts. If I could only find a good small combo chassis or maybe just an empty head (other than the one resting on my shoulders, har har :green
BTW PRR, I couldn't find any 1K, 10K or 100K pots, So I think I'm going to rig a switch to try out different resistance values there and see what's going on. Any tips on how to accurately note the ratio relative to the threshold? I know that sounds counterproductive to rig a switch to then find out what kind of pot modification would work, but the strange things I do to try to learn something...
Aharon
Well-known member
Hey Ethan,not likely that you could fit this amp into that MArshall ministack but if you are into small amps that pack a punch check the Firefly:
http://home.cfl.rr.com/dbhammond/ff.htm
and listen to the samples!!.
I built one into a computer modem case the size of two packs of smokes:
http://pg.photos.yahoo.com/ph/liv_energy/detail?.dir=5919&.dnm=1f36.jpg&.src=ph
http://pg.photos.yahoo.com/ph/liv_energy/detail?.dir=5919&.dnm=50de.jpg&.src=ph
one of my favorite amps and a blast to build.
TAke care
Aharon
http://home.cfl.rr.com/dbhammond/ff.htm
and listen to the samples!!.
I built one into a computer modem case the size of two packs of smokes:
http://pg.photos.yahoo.com/ph/liv_energy/detail?.dir=5919&.dnm=1f36.jpg&.src=ph
http://pg.photos.yahoo.com/ph/liv_energy/detail?.dir=5919&.dnm=50de.jpg&.src=ph
one of my favorite amps and a blast to build.
TAke care
Aharon
those minimal circuits like the original champ rely more on the tube brands and speaker selection and a good cabinet, since the circuit is so small.
so it's tweak city once you figure out what your going to fly with.
whatever that means.
so it's tweak city once you figure out what your going to fly with.
whatever that means.
Kev
Well-known member
We have had a few small guitar amp ideas and links here.
Kent was working on a small project ... smaller than his 18 watter and there was the amp unit I spoke of back in a Group DIY up-date ... used a TV amp tube.
???? mini block ??? ... do a search and get some ideas. I do think that the question you need to answer is whether you want this unit as a DI effect box or if it need enough power to run Headphones or a little more to run a small Speaker.
I found that the 12xx was probably OK up to light headphones but could NOT seem to get anything useful out of a speaker ... BUT my push pull double tube output never did work ?? still on the back burner.
Yeah some of Kev's projects don't work out, especially the tube ones.
you get that :roll:
Kent was working on a small project ... smaller than his 18 watter and there was the amp unit I spoke of back in a Group DIY up-date ... used a TV amp tube.
???? mini block ??? ... do a search and get some ideas. I do think that the question you need to answer is whether you want this unit as a DI effect box or if it need enough power to run Headphones or a little more to run a small Speaker.
I found that the 12xx was probably OK up to light headphones but could NOT seem to get anything useful out of a speaker ... BUT my push pull double tube output never did work ?? still on the back burner.
Yeah some of Kev's projects don't work out, especially the tube ones.
you get that :roll:
[quote author="Kev"]???? mini block ???[/quote]
There's a "MiniBlok" on the server in my workshop (Fred Nachbaur's design) - is that the one?
http://dogstar.dantimax.dk/tubestuf/miniblok.htm
Best regards,
Mikkel C. Simonsen
There's a "MiniBlok" on the server in my workshop (Fred Nachbaur's design) - is that the one?
http://dogstar.dantimax.dk/tubestuf/miniblok.htm
Best regards,
Mikkel C. Simonsen
dukasound
Well-known member
www.ax84.com
Best
Duka
Best
Duka
AMZ-FX
Well-known member
I helped hash out the original design of the AX84... here is the page with some pix of my prototype:
http://www.muzique.com/ax84.htm
regards, Jack
http://www.muzique.com/ax84.htm
regards, Jack
G
Guest
Guest
I've got one of these little babies, and it sounds great! Definetly not a real guitar amp, but a very neat sound when used as an effect... or just to practice... :wink:
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