Amazing! What are the output impedances of the transformer? 3 ~ 5 kOhms 8 works well? V1 is a 12AX7 and one 12AT7 V2? The project should give a 0.25 watt rms ... correct?
+Alexsander Bittencourt Vieira da Silva The Output impedance is 22k, it's a fender reverb transformer. V1 is a 12ax7 and V2 a 12au7, I think the 12AT7 would require more current, but would also work. The total power is something like 0.25 W, but I think this value considers undistorted, with gain maxed it is quite too loud for an appartment.
I don't understand why you choose an IC and a lot of component to get 12v power supply if you can get 12v from a LM7812 with 2 capacitors... Why did you choose that power supply? Thanks
The amplifier is powered with a 12v wall wart, the IC and the components are for the SMPS that boosts the 12v to 240v. This is not a 12v pedal/amp like the valvecaster, the tubes are running at 240V, like in a real tube amplifier.
Amazing project, Thomas! What speaker are you running it with? I can imagine that driving a small speaker at the rate of x2-x4 of the amp's wattage, if possible, in a well tuned cabinet would make this amp shine, tonewise! Great stuff! :)
In this video I'm using a 12" greenback, haven't played it through a good tuned small cabinet, even the cab I'm using in the video has an open back, which makes the lows sound kind of loose.
@@ThomasHafemann True thing about the bass response, and the amp's wattage is a bit low for driving the Greenback to its expected excursion for 'revealing' the speaker's character... A 4" or 6" speaker would be perfect IMHO! :)
This was a design available on diystompboxes: www.diystompboxes.com/smfforum/index.php?topic=84832.0 There you will find the original build. I’ll have to check how I can make the dropbox links work again. Cheers
12AU7 connect in parallel as power output tube? and 12AX7 connect parrallel as voltage driver to drive 12AU7? I 'm thinking similar circuit , 1 12AU7 and 1 12AX7 to make a stereo SE output.
That is a nice idea for a clean amplifier. Here I used 3 gain stages (the 12AX7 in series followed by one 12AU7 triode )and a single 12AU7 triode as the power output stage.
+bare bones I made a schematic/ layout for it and Tim Xie tested it. dl.dropboxusercontent.com/u/10420127/Layout%20miniamp.pdf But it's a difficult build mostly because of the SMPS.
Here you can find the schematic for this amp: www.4shared.com/office/Uow2PNITca/Layout_miniamp__1_.html If you're only interested in the SMPS, take a look at this one with a separate board: www.4shared.com/office/9NyWpeb3ei/RussianJTM__1_.html
www.dropbox.com/s/6jo4ip73msw5d5k/Layout%20miniamp.pdf?dl=0 This build is old, and the board has some noise issues. I would suggest you use the 555 SMPS instead, and on a separate board.
Great job Thomas !
Amazing! What are the output impedances of the transformer? 3 ~ 5 kOhms 8 works well? V1 is a 12AX7 and one 12AT7 V2? The project should give a 0.25 watt rms ... correct?
+Alexsander Bittencourt Vieira da Silva The Output impedance is 22k, it's a fender reverb transformer. V1 is a 12ax7 and V2 a 12au7, I think the 12AT7 would require more current, but would also work. The total power is something like 0.25 W, but I think this value considers undistorted, with gain maxed it is quite too loud for an appartment.
@@ThomasHafemann Please, send me the eletrical schematich for me. email: alexsander.bittencourt.vieira@gmail.com Tks! So Much!
I don't understand why you choose an IC and a lot of component to get 12v power supply if you can get 12v from a LM7812 with 2 capacitors... Why did you choose that power supply? Thanks
The amplifier is powered with a 12v wall wart, the IC and the components are for the SMPS that boosts the 12v to 240v. This is not a 12v pedal/amp like the valvecaster, the tubes are running at 240V, like in a real tube amplifier.
yay Priest!
Amazing project, Thomas! What speaker are you running it with? I can imagine that driving a small speaker at the rate of x2-x4 of the amp's wattage, if possible, in a well tuned cabinet would make this amp shine, tonewise! Great stuff! :)
In this video I'm using a 12" greenback, haven't played it through a good tuned small cabinet, even the cab I'm using in the video has an open back, which makes the lows sound kind of loose.
@@ThomasHafemann True thing about the bass response, and the amp's wattage is a bit low for driving the Greenback to its expected excursion for 'revealing' the speaker's character... A 4" or 6" speaker would be perfect IMHO! :)
Any gut shots of this amp? BTW none of the links work. Can you post a new link to the schematic or layout? Thanks!
This was a design available on diystompboxes: www.diystompboxes.com/smfforum/index.php?topic=84832.0
There you will find the original build. I’ll have to check how I can make the dropbox links work again. Cheers
12AU7 connect in parallel as power output tube? and 12AX7 connect parrallel as voltage driver to drive 12AU7? I 'm thinking similar circuit , 1 12AU7 and 1 12AX7 to make a stereo SE output.
That is a nice idea for a clean amplifier.
Here I used 3 gain stages (the 12AX7 in series followed by one 12AU7 triode )and a single 12AU7 triode as the power output stage.
super cool. where did you get the plans or schematic to build this?
+bare bones I made a schematic/ layout for it and Tim Xie tested it.
dl.dropboxusercontent.com/u/10420127/Layout%20miniamp.pdf
But it's a difficult build mostly because of the SMPS.
ever tried a low wattage EL84 SE?
Really nice build! I sent you a message on facebook a month ago. It might be in the spam-folder. Would be nice to have a little chat if you want (:
Just aswered your message! Nice build by the way!
Could you reupload the schematic please? I'm mostly interested in the smps part, would save lots and space and money in my future builds lol
Here you can find the schematic for this amp:
www.4shared.com/office/Uow2PNITca/Layout_miniamp__1_.html
If you're only interested in the SMPS, take a look at this one with a separate board:
www.4shared.com/office/9NyWpeb3ei/RussianJTM__1_.html
Thomas Hafemann Do I have to register to download the files?
you can also use facebook, google+ or twitter accounts. If you really don't want to sign in you can see a preview and print it with a pdf converter.
I want learn mais this amps.
Do you help me, um this project? Show me, how to make?
Please
Thiago, vai no grupo "Amplificadores e Equipamentos Valvulados" no face. Lá o pessoal ensina muito!
Obrigado vou sim vlw
Bonjour pouvez vous me donner le schéma merci beaucoup Thierry
www.dropbox.com/s/6jo4ip73msw5d5k/Layout%20miniamp.pdf?dl=0
This build is old, and the board has some noise issues. I would suggest you use the 555 SMPS instead, and on a separate board.
diagram?
Schematik please.......