Intact Audio

Will never have to make a real amp again. In the periodic official "training sessions" for LTSpice, they point out that you can feed a music file into the sim, go through the simulation and capture the music file output. Thus in a wierd sense, you can listen to your circuit without buildi...

me thinks the schematic floting ion the web kinda got waterlogged. There are a couple mistakes in your "sim" schematic... The .01u (C6) you have returned to source, and in the net schematic it is returned to ground, and C5 ought to be 100u not 100p. It doesn't make too much sense to bypass...

Hi Lars, I get a duplicate pin number when I open that "assembly" file. It netlists like.. Version 4 SymbolType CELL LINE Normal 0 -48 0 -21 LINE Normal 0 48 0 21 LINE Normal 20 8 12 8 LINE Normal 16 12 16 4 LINE Normal 19 11 13 5 LINE Normal 13 11 19 5 CIRCLE Normal 32 32 -32 -32 CIRCLE N...

Hi, If you open STANDARD.DIO (in the cmp subdirectory... path something like ---> program files/LTC/LTspiceIV/lib/cmp/standard.dio and append the following to it, you get a few tube rectifiers and voltage regulator tubes. If you then place a diode on your schematic, these parts will appear in your d...

If you wanted to keep the impedance low, why not simply scale the C6 capacitor value? For instance, shorting out R10 (97.6k--> 0 ohms) and changing C6 to 119nF, and changing R12 to 26 ohms gets you there. You can tweak R1 to 634 ohms, R4 to 9.15k, and L to 2.92H to get a really flat response out to ...

A bit better.... Changing the biasing on Lars' circuit slightly... I changed R5 to 12k and V3 from 2.5 volts to 2.15 volts. This provides us with about 120 volts and 15 mA bias point on the 6DJ8. Incorporating the measured transformer resistance changes the driving impedance to the filter to 260 ohm...

What's the DCR of the inductor. I get that it can be adjusted from 2 to 3Hy.

Given that inductance, I'd be inclined to rebias the 6DJ8 towards 15mA and 120 volts.

Let's see what we can do with that.....

Later

Stephie <3

Actually, there's more of a problem. If you temporarily replace the load on the secondary of the transformer with a resistor , and allow Spice to find the output impedance, you'll find it's 860 ohms not 100 ohms. That in and of itself is a problem, since with a 1 Hy inductor (and even a 3 Hy inducto...

LTSpice is a full featured Spice available FREE from the Linear Technology folks. Download from their site. See the SIM section of Dave's forum. I've added a bunch of tubes in drop down menus etc. It's not vitally important to have zero impedance, so long as the values end up being physically realiz...

Sure thing. Here 'tis

Stephie <3

This gets a little tricky, but with some "simplifications", it's not too bad. Consider the network: source---RS--+--IND---Rind----+----output . I I . +----Rpole--------+ . I . Rzero . I . ground Where the source is perfect, RS is the effect of source resistance IND is a perfect inductor Ri...

Just had the chance to try the E280F in LTSpice. Tried it at Ua150V, Rk100ohm, meaning to reach Ug150V with Ia just above 20mA. Unfortunately something happens when I go under Ug160V. Over 160V it works OK, though. Could you post the .ASC file? I am not seeing anything bad happening under 160 volts...

I've redone the 7721/D3a. Added grid offset, redone the mu (G1-G2 mu was too low), fixed the screen grid current (it was too low), fixed the A-G1 capacitance, and added the limit condition for saturation current to better model the knee (like I did on the recent additions. I have left the old model ...

For D3a, the g2 current in the model is slightly lower than it ought to be. In addition, the effective G1-G2 mu was a little too low. The grid to anode capacitance was wrong. While I was at it, I added the same saturation limiting I put on the parts I recently added, which better models the clip poi...

Hi All, OK here's another update. This one does have the 7722/E280F added. The curves I had didn't have g2 current "curves" (superimposed on the anode current curves) so I guessed a bit at that, but both pentode and triode connection reasonably match the published curves. Enjoy, Stephie <3

Here's the latest I've got for the drop down tetrode files I called tetrode.txt. It has the following devices in it: 2E24, 6AC7, 6AK6, 6AN8P, 6AQ5, 6AU6, 6BH6, 6BM8, 6BQ5_EL84, 6CA7_EL34, 6E5P, 6KG6_EL509, 6L6, 6L6GC, 6SJ7, 6V6, 12BY7, 12GN7A, 807, 813, 6146, 7754_7695, 7788_E810F, D3a, EF86, SV83. ...

This seems to be considerably closer to the published curves note I've edited this. Left off the .subckt line when i cut-and-pasted the file. .SUBCKT 6E5P 1 4 2 3 + PARAMS: MU= 44 EX= 1.40 KG1=212 KP=200 ; KG2= 4500 kg2 isn't used, kg1 models overall gm + KVB= 20 VCT= 0.00 RGI=1000 ; kvb models plat...

P.S. Anyone have a good set of curves for that critter?

The other problem with that model (which IIRC is generated from a java script) is that it doesn't really model grid 2 very well. I had to modify that model to make it at all useful.

Let me see if I can do anything useful on it.

Stephie

Here's a slightly more refined version. The input stage is closer to what we would like, I think. Adds a little more sensitivity. Removes the 250 volt supply. Same power available, but I've detailed a little bit better what happens as you add tubes. The 5.1 ohm output impedance (with 4 6AS7's) ain't...

Here's an interesting little concept to amuse you on those snowy eves... A DC restorer is simply a RC coupled circuit that has a diode hanging on it. With no AC, the output DC level is simply the return point of the resistor. As you insert AC signal, the diode pervents one side of the signal from ch...

For the initial conditions to work right, do a DC analysis, noting where the operating point IS, then set the voltages and currents with an .IC statement. Then you don't need to worry. On the VR Tube. Getting the bias right is going to be very tricky. As the D3a bias point shifts (if only by volts, ...

Dave
Post the .ASC file. The DC is creaping due to clip at HF. Please annotate the nodes, it helps figure out what you're measuring. Here's a slightly altered spice file. Note that R11 is a lot higher.

Stephie

Pops and ticks will be more pronounced for certain. The problem is partly gain distribution. At 10kHz, Dave's circuit, as shown, runs out of drive somewhere between 100-200mV at 10kHz applied to the inverse RIAA input. That's reasonable HF headroom, but not spectacular. You can gain back more HF hea...

You're right. Steve doesn't get around here much. He doesn't exist any more. On the other hand, you can never tell about Stephie. She might just occasionally show up. The bias point is being altered by injecting a second harmonic signal (sort of like a "push-push" (sic) frequency doubler. ...

Hiding on Linear Tech's site is a full (207 page) user manual for LT Spice. Here 'tis.

Have to go look at the #. IIRC, it is a 320A. 1mv to something like 300v out to better than 1MHz. True RMS for crest factors of up to 20:1. Old instrument, though: 19" rack mountable. My approach is rather different for test equipment: most of the "guts" inside the instruments has alm...

A lot of different techniques and equipment. Most of the distortion curves I do that show the distortion separated by component in Excel spreadsheets come from "specialized" equipment: 1. Sources are highly modified "Heathkit" oscillators with passive LC tuned circuits that net m...

Sorry been tied up. One way is a variation of what Dave C mentioned... Build 2 circuits. Same source. Open circuit one of them, short circuit the other one (this will suggest some simplifications, depending on the topology). Plot Voc/Isc for an AC run. There are probably several more elegant ways......

At present, out of PCBs.