Intact Audio

Hey, I never meant to imply that you might be acting without integrity. Sorry if you thought that. But you do know that this is a public forum, don't you?

I'm going to answer that question so that dave isn't put on the spot. The answer is: proprietary. In the end, there's much more to it than just the number of turns, but still, is there any reason for him to give away information that's helping keep his family fed? Really, he's FAR more liberal about...

According to the FAQ, a typical butt gapped autoformer can handle 8V @ 20 Hz. (I assume zero DC.) I don't know if it's 8V peak or 8V RMS, but it really doesn't matter because the number is so soft.

I don't know. When I see things on that time scale I start thinking thermal, but really I don't know.

Is that chip bolted to a heatsink or at least a big hunk of aluminum?

For what it's worth (or not worth) my intuition has always been that the curves should look like yours and not like the ones we sometimes see in the data sheet that resemble the Childs-Langmuir fit. In any case, it's reassuring that the general shape remains the same when you zoom in. I've always be...

Obviously you have a lazy tube. Try a more modern tube like a 6L6.

Seriously though, just out of curiosity, what's the sample rate.

Martin, some things you probably don't need to be told: You don't get any real voltage gain with a circlotron. But, it does have low output impedance, so you might get away with using a step up transformer. Maybe you don't need gain, I don't know ... You need two floating supplies. By symmetry, neit...

Hey dave, what do you see at the plates and cathodes? Whatever that wiggle is, there are only a finite number of sources for it. Either the tubes are oscillating (doubt it), it's being injected into the grids as common mode (is your balanced source grounded?) or it's being picked up by the coils the...

Sorry for not seeing this thread earlier... The way that I look at the output Z of power supplies is to load them with a current source setup for small signal AC analysis. Even though we don't normally think of loading an amplifier with an AC current source this method should work there just as well...

weekly quiz

What you get when you use am output coupling cap on your preamp: DC voltage at the output until the cap charges...

For what it's worth, I recently helped someone put dave's balanced attenuators into a system with a 2.5k source. He was initially concerned that they might not have enough inductance to preserve the bass, but once the attenuators were installed he completely forgot about all of that. I don't know th...

I agree, amazing as always; nothing boring from you! I have a question that is a little boring; nothing to do with the HE function: did you have trouble balancing the direct coupled PP stages? It seems that even a slight mismatch in the input pair would result in a relatively gross imbalance in the ...

like the panty line of history

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The most accurate model here is Duncan Munro's set of stuff (Which I believe Dave Cigna originated). Not me. Way back when I was a student at Ohio University and had that web site with tube data, either Francesco Piazza or Norman Koren asked me if I'd be interested in hosting spice models too. It s...

Someone on another forum suggested a possible DC offset.... It's a common first-glance reaction to this kind of supply, thinking that one half-winding draws more current than the other. Obviously, that's not the case; both half-windings contribute equally to both supplies just as they would with a ...

I ran the sim (the first one) and couldn't tell what I was supposed to be noticing when removing the little cap, etc. The sim ran painfully slow, but I'm not sure what burps you're talking about. Anyway, it hurts my head trying to figure out the current paths through the ps when used in a monkey. I ...

Rather than plot the equation for a straight line you want to plot the actual plate current v voltage while operating into a reactive load. The problem is that you're already using the tube to generate plate curves. Can you add a whole 'nother circuit (another tube, same type, same ground) and plot ...

Hi nick, no I haven't looked at more complex filters, though it is easy enough for anyone to do in SwCAD/LTSpice. The graphs do seem frightening, but I'm not sure they're as fierce as they look. The 10H/100uF case feeding a stage with a 10k load resistor would result in 0.07dB boost at 20Hz. The oth...

The impedance of a LC filter section in a power supply as viewed from the amp's perspective looking backwards up the supply. Assumes zero impedance upstream of the filter.

Steve, thanks for all of these great contributions! Really, I can't say enough. I know that your help has made spice practical for many people. And fun! What's the point if it's not fun? ... since the forum doesn't recognize .ASY files. All ya gotta do is ask. :) You should be able to upload .ASY fi...

dave slagle wrote:I'm hope cigna will jump in and correct any major errors.

Huh? Hey man, I learn from you! But, I think your analysis is spot on, especially the point about rp of the tube damping any likely resonances. It shouldn't be nearly as much of a concern as with a grid choke.

-- Dave

A page from Ghirardi, Radio Physics Course (a FUN book) outlining the Miessner 'tapped choke.' View Miessner's patent on Google Patents.

Huh? What's this all about?

Oy vey! Another hair brained speaker enclosure. Just what the world needs...

Frequency response and input impedance of a single-knob tone control for guitar amps.

Another way to lower line voltage.