Anyone build Matchless Hurricane/Tornado Tremolo?

[Mickey_C]

I dunno, I don't get how the Matchless Tornado/Hurrican circuits work. I've tried building that tremolo circuit into a self-biased amp, and it doesn't work.

I can faintly hear a trem, but turning the intensity really just kills the signal of the amp. It seems removing the grid leak resistors from ground creates a mixer circuit. Only by dialing the intensity so that it's straight to ground brings the signal back up. I tried it with both the matchless 220K grid leaks and the 18 watt 470K grid leaks. No dice!

One thing I noticed - on the hurricane schematic it looks like thee's two .1 caps in series... and they might actually be polarized, and reversed to each other? When I first looked, I thought they were non-polarized caps, and replaced them both with a singular .047 (two .1's in series = .05).

[Mickey_C]

I found yet another amp that does this same type of tremolo.

[Zippy]

One thing I noticed - on the hurricane schematic it looks like thee's two .1 caps in series... and they might actually be polarized, and reversed to each other? When I first looked, I thought they were non-polarized caps, and replaced them both with a singular .047 (two .1's in series = .05).

Yes, they are polarized and reversed to one another. Replacing them with a single value is not equivalent in this circuit.

[Mickey_C]

Wow - so what exactly does that do?

[johnnyfisher]

Micky,

I built that tremolo circuit my DC30 clone and it is fantastic, best tremolo I've ever heard. My buddy then built the circuit into his clone and had problems similar to what you have (very weak tremolo). He was using a hammond PT and concluded that it just did not have enough juice to get the tremolo twacking. He swapped the PT for a westlabs and the tremolo worked great. What amp are you putting it into?

[Mickey_C]

Hey - that makes some sense.

What voltage do you see on the plate of the oscillator triode?

Also, are you running this to the grid leak resistors? I have them lifted from ground, through the intensity pot (well, I did... I've moved on from this to a new idea, but I can try it again). When I did get some tremolo, it was near to grounded, and at other settings the output was severely castrated. Almost acted like a mixer circuit (I think at least, that it was mixing the two out of phase signals and canceling them).

I've moved on to a Randall Aiken tremolo oscillator:

[img:684:494]http://www.aikenamps.com/PhaseShiftOsc4.gif[/img]

I will implement this driving a cathode follower, which I will then use to modulate a preamp cathode, or (somehow) the phase inverter. That should have enough oomph to wiggle anything I would think.

Mickey

[Mickey_C]

WORKS AWESOME! Cathode follower wiggles that PT cathodes.

WOW WOW WOW WOW.

Or should I say WOW wow WOW wow WOW wow...

BTW - That oscillator as drawn really dies at the bottom speed. If you're going to do this, I would recommend the 18 watt oscillator values. It's more stable.

[johnnyfisher]

Micky, sounds like you solved your problem. Great work.

I do not remember what voltages I was seeing, I did this mod a long time ago. I also put a switch to lift the grid resistors from ground into the intensity pot so that I could turn the tremolo on and off. You can see the same bias modulation tremolo system used in 50's Fender amps like this
http://schematicheaven.com/fenderamps/t ... 9_d-fa.pdf

Also these guys http://www.area51tubeaudiodesigns.com/bmt60trem.htm
give a nice description of how it works and make a neat product.

[Mickey_C]

Well, it was in the wee morning that I tried it, and I had the amp power scaled to about 25%. But once you crank up the voltages, there's no way the 12AX7 can wiggle the PT. It can wiggle a preamp tube pretty well, though it does have a minimal effect on the tone when off.

The grid leak resistor method didn't work well for me. It really changed the sound of the amp, when the intensity pot is turned up.

[johnnyfisher]

which amp are you putting tremolo in? I just noticed that on the area51 site they say that the bias modulation method may not work well with cathode biased 6V6 amps and that you should convert to fixed bias if you want to use the method. I tried the circuit on a GA30 pre/deluxe power amp that I made and it did not work at all. I am going to convert the amp to fixed bias and see what happens. Good luck.

[Mickey_C]

SUCCESS!

Using the cathode follower, driven by the oscillator, through an intensity circuit, I managed to get this working excellently on the V1 preamp tube. The footswitch actually breaks the oscillator from connection to the follower, so there's no pop at all. I tried stopping the oscillator, but it's pretty ugly. Sometimes it wouldn't start up again right away. That's not good (though the slowing of the trem was kinda cool).

The amp's a combination 18 and 20 watt Marshall style amp. The first ones I had the 18 watt trem channel, but it's a bummer. It's just not super strong when you jumper the two channels, with the 18 watt trem, and the intensity really affects the tone and drive. Then there's the finickiness of the tube, etc. I didn't think it exuded the specialness the amp deserved.

Now it's just insane. The intensity lets you totally swamp the sound with trem, or go to extremely mild, the speed goes from about 2hz to about 8hz, so it does from credence to a great pink floyd machine gun, and it works against both channels, so you can jumper up the channels if you like. Due to the differences in the phase inverter in the two amps, the 18 watt mode is super super strong, and the 20 watt is a bit weaker, but still really nice (the amp has a phase inverter selector switch - basically a huge multipole multithrow rotary).

I will post the trem circuit here for folks to use if they like, of course! Just build it as is, and connect the cathode follower to your V1 cathode, at the junction of the cathode/Ck/Rk.

Mickey

[MarshallPlexi]

Question regarding the 2 0.1uF caps here. On the schematic for the Matchless Tornado, the same values of caps are shown but they are not polarized, thus in series they have a combined value of 0.05uF. Is there a reason for the two polarized 0.1uF caps?