New build ultimate dumble-based amp (2)

Dumble schematics, designs, pictures. Only members may post files here.

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fjonkman
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New build ultimate dumble-based amp (2)

Post by fjonkman »

Here some photographs.
Yet I don't have soundfiles. Maybe later.
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Colossal
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Re: New build ultimate dumble-based amp (2)

Post by Colossal »

Wow! Fantastic work on the point-to-point layout! That must have taken a lot of time and planning. Very nice!
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dreric
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Re: New build ultimate dumble-based amp (2)

Post by dreric »

Holy Shit! (heck of a first post)

Awesome!

How does it sound?

Thank you for your generosity in sharing!

Eric
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boldaslove6789
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Re: New build ultimate dumble-based amp (2)

Post by boldaslove6789 »

Wow, talk about a swiss army knife, Great job!!
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martin manning
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Re: New build ultimate dumble-based amp (2)

Post by martin manning »

Very nice fjonkman! Tell us about the topology...
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sonicmojo
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Re: New build ultimate dumble-based amp (2)

Post by sonicmojo »

And now for something completely different......


Sweet! It's refreshing to see something totally "out of the box" like this. Did you run into any wiring gotchas with your design, like with common grounds or noise issues around certain parts? I certainly can see the advantage of this layout for easy tweaking.
---------
Bryan
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SoundPerf
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Re: New build ultimate dumble-based amp (2)

Post by SoundPerf »

Whoa!! That's absolutely incredible. And that's saying a lot here where there are so many great builders and builds. :shock:

Would love some sound clips.
Chris
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sergio
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Re: New build ultimate dumble-based amp (2)

Post by sergio »

Nice!! but I think this can play different , Dumble lead-dress is important!
Bye
Sergio
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M Fowler
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Re: New build ultimate dumble-based amp (2)

Post by M Fowler »

Great looking amp and one heck of a nice build.

Mark
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fjonkman
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Re: New build ultimate dumble-based amp (2)

Post by fjonkman »

Some more about designing and building my amp.
Grounding and hum: In the layout you can see where grounding points are. Actually there are four: power supply, output-amp/PI and all the rest. I placed the transformers at a distance from each other; extra advantage is to make it easy to work on the chassis while it is in balance. I took used transformators from my first build. The power trafo has no shieldind cap and you can notice that if your guitar pickups are to close. And because pickups and trafo are normally at the same height (one meter) I have to be at least 30 cm from the amp. A minor issue: I don’t have plans for extra shielding. In the layout all thick white lines are shielded coax. My amp is dead quiet after all.
Chassis design: it’s indeed a hell of a job to place 8 tubes in line in a chassis of 50 cm width and leave enough room for all components so that they easily can be reached for tweaking. 8 tubes was the maximum and that was the reason for implementing ideas about a one tube reverb and the old solution for a bias-controlled tremolo. If I had to build a second amp with these specifications I would change some things: more space for the power section and also directly around the 6 smaller tubes.
Tone circuit: I did a lot of testing and tweaking around the tone-circuit in the pre-amp. It seemed to me that lot of schemes published had mistakes in the scheme itself or the layout. Or maybe that was the way it was meant to be. Anyway: this setup gives me the maximum tonal variations. In most of the schemes I saw PAB and Rock made no difference. May be a reason is that PAB normally has no switch at the front of the amp. By the way: it is very easy to change the functions on the footswitch if you have all switches also on the front. At first I had the tremolo on the footswitch instead of the mid boost.
Remote/footswitch: I had no room for an extra 6V or 12V trafo in the chassis and did not have an extra winding at my power trafo. Therefore I tried to use the 6.3V heater-winding. In this setup there are no problems with hum and it is possible to use only a four wire cable tot the footswitch. Don’t use DIN-connectors as I’ve tried. Eventually I ended up with Neutrix connectors NC4-MXX and NC4-FD-LX.
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martin manning
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Re: New build ultimate dumble-based amp (2)

Post by martin manning »

Thanks for the additional details, fjonkman. The D tone stack is quite effective and is correct as drawn in the schematics and layouts posted here. That can be verified, at least in the case of the Skyliner version as implemented on #124, using the detailed photos. The R-J switch definitely has an effect, but the PAB will be reduced as the other EQ controls approach full-on. Re using the heater winding for relay power, I guess it can be done then- unregulated, even... There were reports that doing so caused hum issues, but I can't imagine why. Really great work, and thanks for posting the detailed documentation!
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rogb
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Re: New build ultimate dumble-based amp (2)

Post by rogb »

Looks just great - well done!

Thanks for the layout too, I couldn't get my head round Visio, so - amazing too! :D
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Structo
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Re: New build ultimate dumble-based amp (2)

Post by Structo »

What did you use for the grill material on the cabinets?
Tom

Don't let that smoke out!
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fjonkman
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Re: New build ultimate dumble-based amp (2)

Post by fjonkman »

The grill material on the the cabinets is just perforated 1 mm alluminium from a local hardwarestore. It is easy to cut and bend around a frame of 5 mm plywood with black grill-cloth between alluminium and wood.
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Cantplay
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Re: New build ultimate dumble-based amp (2)

Post by Cantplay »

Excellent work.

I really like the way you sleeved all the component leads. I'm going to do that on my next build.

John
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