Hi All,
I want to build a basic Valve guitar amp that has about 1/2 to 1 watt output.
Basic simple design and cheap to build as a starter project to tube valves.
I've seen these "Little Bear" kits on ebay but they're headphone amps with a combination of tubes and transistors.
Is there a kit or "How to" walk through for a:
low voltage
Low output 1/2 to 1 watt
simple design
guitar valve amp
I have zero knowledge on how valves work but I know reputation speaks for itself.
I want to build a basic Valve guitar amp that has about 1/2 to 1 watt output.
Basic simple design and cheap to build as a starter project to tube valves.
I've seen these "Little Bear" kits on ebay but they're headphone amps with a combination of tubes and transistors.
Is there a kit or "How to" walk through for a:
low voltage
Low output 1/2 to 1 watt
simple design
guitar valve amp
I have zero knowledge on how valves work but I know reputation speaks for itself.
Lots of info on AX84. look up the "firefly" amp.
AX84.com - The Cooperative Tube Guitar Amp Project
Cheers,
Mike
AX84.com - The Cooperative Tube Guitar Amp Project
Cheers,
Mike
Agree on the firefly - easy to build & nice sound. A lot louder than you might think...
Here's a direct link to the project:
AX84.com - The Cooperative Tube Guitar Amp Project
Here's a direct link to the project:
AX84.com - The Cooperative Tube Guitar Amp Project
Agreed on the Firefly - but it can be tricky to prevent oscillations. Also, without a tone control or master volume its use may be limited.
I built a Firefly but then modified it to a different, more typical, preamp topology. It is perfect for livingroom use, loads of distortion if you want, nice cleans. The tone controls are important for low volume playing. (AX84 Firefly-style build – Tristan Collins)
Merlin High Gain Preamp + Firefly Output – Tristan Collins
Schematic:
I built a Firefly but then modified it to a different, more typical, preamp topology. It is perfect for livingroom use, loads of distortion if you want, nice cleans. The tone controls are important for low volume playing. (AX84 Firefly-style build – Tristan Collins)
Merlin High Gain Preamp + Firefly Output – Tristan Collins
Schematic:
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Why low-voltage?
Most of the 'tube' devices like guitar pedals and headphone amp that use low voltage are solid-state amps with a tube adding a bit of 'tubey' color to the sound... like that headphone amp you mentioned.
I haven't seen any tube headphone guitar amp kits.
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I missed the "low voltage" part the first time around.
Take a look at Sopht amps - some fun low volt designs that are easy to build and sound pretty nice too:
Sopht amps - all tube 12v amps
Rich
Take a look at Sopht amps - some fun low volt designs that are easy to build and sound pretty nice too:
Sopht amps - all tube 12v amps
Rich
Rich-
Thanks for that link to Sopht amps.
I'd better download that stuff, since the website has been around for a while and I don't want it to disappear before I get the schematics and info!
Low voltage switching power supplies are easy to find (and pretty cheap), or I can use some of those power transformers that came out of cheap solid-state components. Something for the 'to-do' list, 2017 version!
For headphones, Sopht's 'Headphone box' looks like a nice little project:
Sopht amps - Headphone Box
I think that most of those amps using a 600 ohm output transformer could just go straight to headphones (replacing the transformer with a capacitor to block any DC on the phones) ??
Thanks for that link to Sopht amps.
I'd better download that stuff, since the website has been around for a while and I don't want it to disappear before I get the schematics and info!
Low voltage switching power supplies are easy to find (and pretty cheap), or I can use some of those power transformers that came out of cheap solid-state components. Something for the 'to-do' list, 2017 version!
For headphones, Sopht's 'Headphone box' looks like a nice little project:
Sopht amps - Headphone Box
I think that most of those amps using a 600 ohm output transformer could just go straight to headphones (replacing the transformer with a capacitor to block any DC on the phones) ??
I really like my Vox Lil' Night Train for this application. I believe it eeks 2w into 16ohm out of a 12AU7 valve, used as a pair of triodes push-pull. The rest are 12AX7, though I have played with swapping 12AU7s in for less gain.
Those valves are easy to use, and commonly available. Might be worth a look.
Chris
Those valves are easy to use, and commonly available. Might be worth a look.
Chris
Not for the OP, low voltage supply around 50V. Just breadboarded it and in no way refined it. Maybe up to a half watt.
Oh right, the cap going to ground in the LTP should be connected to the grid and not to the top of the 3.9k resistor. Did an oops in the schematic once and copied it into others without even thinking about it. Don't really use a schematic when I build so never did the mistake on an amp.
An externally hosted image should be here but it was not working when we last tested it.
Oh right, the cap going to ground in the LTP should be connected to the grid and not to the top of the 3.9k resistor. Did an oops in the schematic once and copied it into others without even thinking about it. Don't really use a schematic when I build so never did the mistake on an amp.
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i operate signal chain with symmetrical power +24 -24 and fixed bias.
the +24 also powers tpa3116 pbtl.
it works perfect, measured.
have tested 12au7 and 6sn7 so far.
doing a pre board as we speak.
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the +24 also powers tpa3116 pbtl.
it works perfect, measured.
have tested 12au7 and 6sn7 so far.
doing a pre board as we speak.
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