Magnatone build

[Smokebreak]

I've been very inspired by all the Magnatone talk, pics and sounds lately so I'm putting together one based on the Titano/214/213/AmmoCan/Robophil schematic. I can't keep them all straight.
This circuit sounds wonderful , even without the vibrato. Warm and rich, like an unfettered octal preamp. Clean and dirty.
I used SS rectifier and Musical Power Supplies iron. I'd been waiting for the USA stuff, and Matt was super helpful. 275-0-275 and 335 plates loaded. 115 taps too if I want to bump it up, but at this point I'm not sure why I have ever put more than that on 6V6s.

The pics reflect the use of these new production varistors : http://www.mouser.com/Search/ProductDet ... EjFA%3D%3D
They sound like this : https://soundcloud.com/jeremyslemenda/n ... -magnatone

I also studied evhou812's awesome build and cascaded, but anything above 9oclock with both controls was a bit crazy for me, so I've got 470K series between stages, and I'll probably end up with a 470k/470K divider at least.
I'm always fickle about cranked sounds, but my aim here is to show the differences with the varistors. I ended up with some NOS varistors a couple days ago, and I am just now coming out of the hypnosis! They sound like this : https://soundcloud.com/jeremyslemenda/m ... -varistors

I'm not exactly sure what I'll do in the real world with this sound, but as a player it demands that I play nice and pretty. I like that....and I'll probably put them on a switch!

[xtian]

Hey, nice looking build!

I'm new to the idea of varistors in tremolo circuits. Schematic, please!

[Smokebreak]

layouts and schematics

[M Fowler]

Those NOS varistors sounded great nice work.

Mark

[evh0u812]

Awesome to see someone else get into this circuit.
Sounds amazing with the NOS varistors.
Regarding the cascaded circuit values, how much do they vary from what I used in the schematic I posted?
I found I could get both volumes cranked and still retain a useable sound.........It was like Angus Young on steroids, but still very useable.

So are you saying the trem is on all the time and not switched?
Footswitch is the go.

Also see you copied my layout.......I found this very quiet and quite sensible as far as component placement. Great build!

[Smokebreak]

Awesome to see someone else get into this circuit.
Sounds amazing with the NOS varistors.
Regarding the cascaded circuit values, how much do they vary from what I used in the schematic I posted?
I found I could get both volumes cranked and still retain a useable sound.........It was like Angus Young on steroids, but still very useable.

So are you saying the trem is on all the time and not switched?
Footswitch is the go.

Also see you copied my layout.......I found this very quiet and quite sensible as far as component placement. Great build!

Hey man! Yea your layout is spot on. I dinked around with more traditional layouts, but you got it right from what I could see in those 2 pics.

I cascaded with the same values you used, but only used 1 on/off/on bright switch for v1b for 100p/150p. Right now I've got 470K series between the first two stages, as it's just too much gain over here. I'm getting the Angus tones with both gains at "2" and after that it's just compressing too much for my taste. I'll likely put a ground leg with the 470K between the stages, and maybe lose a cathode cap.

I don't have a footswitch so I've just been turning the Vibrato controls all the way down, and shorting to ground to remove it, and found that you can nix the oscillator circuit at the 2M2 mixer, and still have the core tone, with no loss. Concerning my comment about the switch, I meant putting the new production varistors and the NOS varistors on a switch, to have the option of tremolo or vibrato, as the new production varistors produce tremolo, not vibrato, but still cool sounding.

I didn't put in the conjunctive filter but have some posts on the back panel for it.

Underboard wiring is pretty crazy, eh?

[Structo]

That sounds nice!

[evh0u812]

I ended up removing the conjunctive filter. rolled some nos tubes trough the amp and found a set that sounded great without it. Besides mine was to be top mounted in its headshell and i didnt like the extra heat the 10w resistor was radiating.

Footswitch is a simple and useful addition. The core tone of the circuit is just stunning as youve found out. Mine shipped to the customer last week and i miss it already.

[Smokebreak]

I ended up removing the conjunctive filter. rolled some nos tubes trough the amp and found a set that sounded great without it. Besides mine was to be top mounted in its headshell and i didnt like the extra heat the 10w resistor was radiating.

Footswitch is a simple and useful addition. The core tone of the circuit is just stunning as youve found out. Mine shipped to the customer last week and i miss it already.

Did you use any screen resistors or stoppers at the output grids? Upon closer examination of my cranked tone I seem to be getting some blocking distortion, or something else that's making things a bit farty splatty fuzzboxy

[Structo]

I think if it were me I would try screen resistors first then if that doesn't fix it, put some 1K5 grid stoppers in.

[Smokebreak]

I think if it were me I would try screen resistors first then if that doesn't fix it, put some 1K5 grid stoppers in.

Thanks Tom, i haven't implemented the resistors yet as it will be a few hours before I can crank it, so I've been dinking with voltages. I put in the 115V taps as plates jumped to 360, instead of 335 with the 120 primary taps. That's where I wanted to be originally, anyways, but I've found that one side of the OT sec(EDIT : PRIMARY) is jumping around 7 volts or so, from 360-367VDC, and the other is remaining a steady 360VDC. Problem doesn't follow the tube. Is this a tell-tale sign of something I should be concerned with? Screens are steady 350VDC. Cathode biased 6V6s.

[JazzGuitarGimp]

Hey Smokebreak. Cool clips! I have a few questions:

- Is the substitution of the varistor the only circuit change between the two clips?

- The clip with the NOS varistors sounds darker than the current-production varistor clip. Is this also due to just the change in varistors, or was the amp / recording chain different in the two clips.

Both clips sound great, but the NOS varistor clip sounds awesome!

[Smokebreak]

Hey Smokebreak. Cool clips! I have a few questions:

- Is the substitution of the varistor the only circuit change between the two clips?

- The clip with the NOS varistors sounds darker than the current-production varistor clip. Is this also due to just the change in varistors, or was the amp / recording chain different in the two clips.

Both clips sound great, but the NOS varistor clip sounds awesome!

Thanks Lou, yea the NOS varistors are super-trippy. I definitely prefer them also.

-yes, the varistor change was the only circuit change in the 2 clips

-i recorded both of those with my phone, a couple days apart, so there's no doubt some sketchy variables in there(mic placement, volume/tone settings). Same speaker though V30
Generally speaking, I wouldn't say the NOS varistors produced a darker tone( in normal operation or otherwise), just a much more hypnotic one
I also believe I was switching around bridge/neck pups to get a sense of that change too, but more than anything I thing I had the amp up louder and the tone backed off the amp for the NOS clips

[JazzGuitarGimp]

Thanks Smoke. Yeah the NOS varistors are very hynotic / trippy. It's a gorgeus sound: probably not well suited for all trem applications. For instance, if I were doing a cover of a CCR tune, I'd probably opt for a more choppy trem. But man, if you could have both options in the same amp, that would be awesome! Good work!

[evh0u812]

I ended up removing the conjunctive filter. rolled some nos tubes trough the amp and found a set that sounded great without it. Besides mine was to be top mounted in its headshell and i didnt like the extra heat the 10w resistor was radiating.

Footswitch is a simple and useful addition. The core tone of the circuit is just stunning as youve found out. Mine shipped to the customer last week and i miss it already.

Did you use any screen resistors or stoppers at the output grids? Upon closer examination of my cranked tone I seem to be getting some blocking distortion, or something else that's making things a bit farty splatty fuzzboxy

No screens just grid stoppers. 5k6 from memory. Howled like a banshee without them.