preamp design using simulation

[ippisl]

Hi ,
I want to design a transistor based clone of a tube preamp(hiwatt). Since i don't have equipment , original hiwatt , or large knowledge in analog electronics , my plan is to simulate the hiwatt preamp on the pc, and simulate my clone , and compare them , until i get good results , and then build it. This way i can also learn a bit about analog simulation which i'm interested about.

What would be good , easy to use tools for this job ?
What kinds of simulation tests i need to run to compare both preamps ? esp regarding non-linear performance?
Where is a good place to get simulation models for tubes ,etc..?

Best regards ,
yaniv

[Top Top]

I could have the wrong impression about this forum, but I don't think there are a lot of people doing digital simulation here. You might want to try in the DSP subforum here.

[ippisl]

i was referencing to using analog simulation tool (like PSPICE) to simulate both circuits, not build a software to implement the preamp.

[alanlan]

I would recommend the student version of PSpice (if you can locate a copy that is).  If you can't find it pm me as I may have a copy of the original zip from a few years ago.  It's a great tool for learning and for studying non-linear behaviour too, but obviously the simulation is only as good as the models used.  Generally though I think they are good enough for you to get a much better understanding of circuit and component behaviour.

You should be able to find model libraries for just about anything - just google.

What they can't really do is tell you how something will *sound*.  You need to use a pair of Mk1 ears for that

[petemoore]

  It's worth noting that preamps don't 'sound' at all without being part of a chain which includes other things influencing tone.
  I'm not familiar particularly with these amps, sometimes a ~linear preamp is designed for use as driving output tubes.

[JKowalski]

LTSpice, for sure. Free download, and as versatile a Spice as many commercial brands. All the useful simulation commands, AC (freq response) and DC (transfer characteristics, VI curves) analysis, transient analysis, noise analysis, FFT, etc. Has a rather large library (Mostly LTspice IC's, because the point of the program is to make you familiar with their IC's and apt to use them in your products) but you can download and .inc components from all over the net.

Ive read that you can also send a .wav file through the circuit simulation, save the output wav and listen to how the signal sounds going through your circuit. I haven't gotten around to learning the commands to do that yet, but it's gotten good reviews on that.



As far as your specific analysis questions, frequency response would be a good thing to compare between the two, in addition to a transient (visual comparison) and FFT (hramonic distortion comparison) of the output signals.

As far as finding additional model files, join the Yahoo Group "LTspice". They have a rather large model download section, a ton of files you can use. Voltage controlled R/L/C, pentodes, triodes, CD4000 IC's, etc. LTspice has a very good selection of basic components in various forms, so you would only need to download very special items.

[CynicalMan]

LTSpice, for sure. Free download, and as versatile a Spice as many commercial brands. All the useful simulation commands, AC (freq response) and DC (transfer characteristics, VI curves) analysis, transient analysis, noise analysis, FFT, etc. Has a rather large library (Mostly LTspice IC's, because the point of the program is to make you familiar with their IC's and apt to use them in your products) but you can download and .inc components from all over the net.

Ive read that you can also send a .wav file through the circuit simulation, save the output wav and listen to how the signal sounds going through your circuit. I haven't gotten around to learning the commands to do that yet, but it's gotten good reviews on that.


As far as your specific analysis questions, frequency response would be a good thing to compare between the two, in addition to a transient (visual comparison) and FFT (hramonic distortion comparison) of the output signals.

As far as finding additional model files, join the Yahoo Group "LTspice". They have a rather large model download section, a ton of files you can use. Voltage controlled R/L/C, pentodes, triodes, CD4000 IC's, etc. LTspice has a very good selection of basic components in various forms, so you would only need to download very special items.

+1 for LTSpice. It takes a while to figure out everything but it's worth it. If you have trouble finding models, I know where to find some of them. That being said, you might have trouble with simulating tubes. I haven't tried a full amp but I know that low voltage designs don't simulate too well. Transformer models are also hard to find. The best place for tube and transformer models is http://www.duncanamps.com/spicemodels.html