THE SFA - 1W all tube guitar amplifier

Stompboxes circuits published in magazines, books or on DIY electronics websites.
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DarkRain
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Post by DarkRain »

Hello guys,

Long time no posts. Had a lot on my back and a lot of projects to be done, so after a while, i've managed to finish this project that was on my mind for some time now.
It's a small full tube practice amp that uses 6N16B double triode as an output tube (submini) and a 6N16B / 6N17B double triode as a preamp tube.
The schematic is based on Marshall 18W and the power stage is made in a self-split configuration.
Controls are: 1 volume and 1 tone knob and one switch that will enable a single or parallel preamp stage
For the HV it uses a SMPS module.

Project documentation is available here: https://dl.dropboxusercontent.com/u/152 ... %20SFA.pdf

Also the PCBs will be available for buying (the fist batch is sold out - 30pcs, but i will prepare a 2nd run if someone is interested). PCBs can be pre-ordered (no payment ahead required) on this topic or by an e-mail at: gtudoran@gmail.com
You can also get in touch with me on my FB page: https://www.facebook.com/dextersworkshop.ro (all updates are posted there)

Here you have some renders of the amp and also some views of the PCB

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Regards,
Gabriel Tudoran aka. DeXTeR
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tabbycat
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Post by tabbycat »

thanks darkrain, it looks interesting. do you have any soundclips or a yt video? would be nice to hear it running.
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Post by DarkRain »

tobbycat i do think that it will be ready soon (next week)

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Post by DarkRain »

@tabbycat there you go, the first fire-up

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Thomas_H
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Post by Thomas_H »

Nice project!

is this the same amplifier you were experiencing in an older thread? I guess I posted a lot in that thread...

I have some questions...that sound more like some suggestions...

as you're using the preamp triodes in parallel or only one triode, you could make it switchable to series too, right?
I made that with my 10W plexi amplifier. I guess it would only need separate plate and cathode resistors.

Would series give you more distortion when compared to the parallel arrangement you're using? As the voltage gain would be doubled...

I built a 3 tubes version with a cathodyne using this same tubes and was testing it with a cheap portable oscilloscope and the signal going to the speaker had assymetrical clipping, I guess I need to tune the cathodyne...

As you already posted a picture of your oscilloscope, could you post some pictures of the produced signal to observe how the self-split signal looks like?

One more time, congratulations for the nice work, the 3D cad version is really helpful, and I guess that professional boards are better to work with.

Thomas
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DarkRain
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Post by DarkRain »

Thomas_H wrote:Nice project!

is this the same amplifier you were experiencing in an older thread? I guess I posted a lot in that thread...

I have some questions...that sound more like some suggestions...

as you're using the preamp triodes in parallel or only one triode, you could make it switchable to series too, right?
I made that with my 10W plexi amplifier. I guess it would only need separate plate and cathode resistors.

Would series give you more distortion when compared to the parallel arrangement you're using? As the voltage gain would be doubled...

I built a 3 tubes version with a cathodyne using this same tubes and was testing it with a cheap portable oscilloscope and the signal going to the speaker had assymetrical clipping, I guess I need to tune the cathodyne...

As you already posted a picture of your oscilloscope, could you post some pictures of the produced signal to observe how the self-split signal looks like?

One more time, congratulations for the nice work, the 3D cad version is really helpful, and I guess that professional boards are better to work with.

Thomas
Hello Thomas,

Yes that is the amplifier.
I'm using single or parallel triodes (using a switch you can choose the configuration) - i choose this because i would like to have it as clean as possible and yes, a cascade configuration would push the signal more into overdrive.
I'm using a self-split configuration, so a PI is not needed, but the next project will have a dedicated tube for PI ( i will post some oscope pictures soon)
Thank you, as for the PCBs yes, as this project is intended as a KIT some good quality PCBs ware mandatory (had to order over 40pcs.)

Regards,
DeX
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Post by DarkRain »

Annnddd... done!

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