Intact Audio

Finally, here's a progression of the lowly 6L6GC in push-pull Ultra-Linear mode from pure pentode (beam power) operation to pure triode operation (screen voltage tapped so that the screen swings from 0 to 2x the quiescent voltage. Notice how rapidly the curves linearize in push pull mode as you incr...

Now, what load line plotter would be complete without Ultra Linear operation? Here's a mod to allow you to do either single ended or push pull ultra linear load lines. You can program any value of insertion of the plate signal from 0 (Pure pentode) to 1 (pure triode operation). You may use separate ...

Awww. Thanks! Enjoy. There's a lot to be learned in those pictures. Although I didn't explicitly point it out, the inductance of the coupling transformer, of course, can add phase shift at lower frequencies. You'll see it by running a set of curves at 20Hz or so. If you "reasonably" approx...

Some additional notes... The SE and PP curves have the grid bias lines set up so that the middle (5th of 9 lines) is at the bias point. So, it you pick a bias of -40 volts, the grid lines are 0, -10, -20, -30, -40, -50, -60, -70, -80. In running the program, if you see VERY slow execution times, cha...

OK. You asked for it. Here's a Spice Transient analysis load line analyzer that supports triodes, pentodes, single ended, push pull, AC and DC load lines. The AC analysis (elliptical load lines) supports different drive levels and frequencies.

Enjoy,
Stephie

I would agree that reactive loads need to be handled correctly by the amplifier in order to sound good. If an amplifier presents a low impedance inherently, it's probably reasonable. Varying impedance as part of the overall operating cycle is problematic. Quads sound wonderful when driven with an am...

The classic example would be 2A3 operated at PP with 3k load, 62 volt bias. Notice this produces 15 watts, following the datasheet operating conditions. It looks like this...

Stephie

Quick answer, YES. Note that since triode curves are lower Z (current increases rapidly with voltage) the LIMIT function is really helpful. I indicated that on the schematic notes.

Spice lets you do a voltage sweep. Ideal for plotting tube curves. But you can also alter it slightly to allow you to manipulate push pull operation, thus allowing you a really easy way to create and manipulate a push pull load line. The only thing you need to remember is that as the anode voltage o...

Continuing on, let's consider an example. For this first example, let's set up a simple 2A3 single ended output stage. Nothing fancy (yet - we'll talk about that in later examples. But in this example, I simply want to show a nice vanilla output stage. 255 volts (well, 250V behind the resistance of ...

But wait! There's more... If you call within the next 3 minutes.... No, no, no. Where did that come from? More seriously. Since we have a THD module, we could add a bank of very sharp, narrow bandpass filters, and get not only a measure of THD, but individual distortion components as well. It's just...

To create a distortion measuring module is relatively easy in Spice. Let's assume a 1kHz driving source. What we need is a very sharp high pass filter just below 2kHz. It has to be sharp enough that 1kHz driving signal won't get thru. A 0.2dB chebychev filter at 1.995kHz, 11 pole is down a bit over ...

I'm still around and kicking. At least for a while. First, I'd just like to say hi to all. Although I'm not actively doing tube work, I use LTSpice all the time and have gleaned a few tricks over the years. LTSpice provides two methods of obtaining distortion information about your pet circuit. (The...

Indeed, you never know who is going to be lurking on this forum. Indeed my favorite amplifier is indeed the 813 Matrix. Thank you for the kind words. Although I still work a full time job, I do not have a full time lab set up at home. In my mid 70's, I've found iron gets heavier every year. Smile I ...

Indeed, you never know who is going to be lurking on this forum. Indeed my favorite amplifier is indeed the 813 Matrix. Thank you for the kind words. Although I still work a full time job, I do not have a full time lab set up at home. In my mid 70's, I've found iron gets heavier every year. :-) I do...

Try .model 6CD3 D(Is=8.8e-2 Rs=18.4 Cjo=15p N=276 Bv=6000 type=vacuum) You can either add that into LTSpice's diode file (under components) in which case it will appear in your list of diodes in the drop down menu, or just add that statement to your schematic page. If you do that when you call up a ...

Hi, I'll work on that one in about a week. Sorry for the delay but my sis's mom (my step mom) just passed away unexpectedly and we are heading to Ohio for the funeral. (Taking the red eye from San Diego to Philly to Dayton Ohio tonight). I'll probably use one of the "new models" that I am...

I am not particularly happy with ANY of the models in the tetrode file. Koren's basic models are pretty good for specific applications, but you'll notice they don't change screen current as a function of plate voltage, which is a flaw. I had tweaked some of those models to get around that limitatio...

Hi, Yes, I will help with any questions. As I think I mentioned, a lot of my energies these days are focused in other areas, but I do support this Forum. Right now I am in San Francisco with my sister who just had 12 hours of surgery, so I'm helping her with her recovery. So please bear with any de...

Thanks. Actually it's pretty easy to create any tube using that model. It has one limitation that I will correct before releasing it, having to do with triode mode and A2 operation... need to add one parameter, but I may defer it... want to work on triode mode using pentodes more, but I need to imp...

Hi Ray and all. I've completed the model and added a 7199 as its first instantiation. I reran your Dynaco file with the new tetrode.txt and it seems to bias properly now. The anode voltage was 150 volts and transient analysis produces a reasonable results, so the model is behaving properly. I also ...

No, I haven't forgotten. I started to get into the "tetrode" model files and found SO many inconsistencies and limitations. (including the ones I added too). I am in the process of coming up with a reasonably universal model, and will put a "Build Tetrode" file similar to the &q...

I have again updated triode_nh.txt to correct and add s bunch of devices. Here’s the header file: * triode_nh.txt Oct 16, 2012 Stephie * * Note: This collection has a lot of devices modelled by a lot of different people. In no way do I intend for anyone to think * that this is solely my work. I'v...

Thanks. I've currently got the triode models "open" since I am adding several devices into the library (Using build_triode). Also, the library as a hodge-podge of several sources had inconsistent set of functionality. I have added in grid current capability into all the devices in the dro...

Norman Koren has done a wonderful thing with his models. A lot of the devices modeled in your included library I do not have in the drop down. However, the pentode model used for that part and most of the ones using that model have a fatal flaw (in my opinion) in that the screen grid current does n...

I will get to ETF again, as I want to dance with some of you handsome guys too. :D I'm preparing for my sister's upcoming surgical visit, so saving days off and conserving $$$. We'll both probably come next year. The attached picture is both of us with a friend of ours in Houston TX. (We were visit...

Hi C, You typed in model HLMP-6000 (IS=93.2P RS=42M N=3.73 BV=4 IBV=10U CJO=2.97P VJ=.75 M=.333 Iave=0.04 mfg=Avago type=LED) What is missing is the "D" before the parenthesized data. I was able to reproduce your results, and when I added the D to make your model model HLMP-6000 D(IS=93.2...

Hi All, Triode_nh.txt has again been modified to include 2 46 models: The 46 is a dual-grid device, but intended only for triode operation. Connecting the g2 to the anode provides s low mu (5.6) triode while connecting the g2 to g1 forms a high mu (>50) triode intended as a Class B push pull amp. Si...

Hi Piotr and all, I will be adding two more tubes into the triode drop-down files to cover the 46. This tube is called a "dual-grid power amplifier". Inteed, it is not intended to act as a tetrode, but rather as two distinctly different triodes. Grid 1 is the control grid, as is usual. Gr...

Hi Paul, Piotr, and all, This version now includes the 12BH7alt in it. I added a reasonable grid current into it, so in addition to behaving properly when you forward bias the grid, it will actually work in A2 reasonably accurately. Please note that the old model, as well as some of the other "...