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Installing and using LTspice IV (now including LTXVII). From beginner to advanced.
Installing and using LTspice IV (now including LTXVII). From beginner to advanced.
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Old 24th July 2021, 05:01 PM   #2961
Mooly is offline Mooly  United Kingdom
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Installing and using LTspice IV (now including LTXVII). From beginner to advanced.
Your confusing me

Do you see the single text file that was in the zipped folder?

It should be slotted in somewhere amongst all the sims.

You only need that one file for all the sims to work.

If you can't see how it works then try this. The model file is called poundys models and the sim has been altered to suit.

Just extract the zipped folder and run the sim (it won't run from the zipped folder, you must extract the contents). Don't alter anything. The sim should run and it will take a few seconds to complete as it is a complex one. You can then see how it works and how the model file is identified.
Attached Images
File Type: jpg Pioneer A80.jpg (512.7 KB, 59 views)
Attached Files
File Type: zip Test LT.zip (78.9 KB, 5 views)
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Old 24th July 2021, 06:41 PM   #2962
poundy is offline poundy  United Kingdom
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Installing and using LTspice IV (now including LTXVII). From beginner to advanced.
ok got it all working, i couldnt get it to work keeping in in the file folder so i dumped it into 'c'
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Old 24th July 2021, 06:44 PM   #2963
Mooly is offline Mooly  United Kingdom
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Installing and using LTspice IV (now including LTXVII). From beginner to advanced.
That is very very strange but as long as you have it working OK. Models were (and are) one of the most difficult aspects of LT to me. It took me ages to get it to work at first.
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Old 25th July 2021, 01:49 PM   #2964
madis64 is offline madis64  Estonia
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First my apologies if this has been handled in the previous messages of this thread - but I cannot find any information with internet search either.

I stumbled across strange voltage values of the same signal when doing a simulation of Yamaha A-700 power stage (yes, with wrong component models but better these than nothing).

So I downloaded the zip file from

Installing and using LTspice IV (now including LTXVII). From beginner to advanced.

and tested it also on the Pioneer A80 model from there.

Same inconsistency appears - voltages in ac simulation are greatly different from voltages in tran simulation:
Pioneer_A80_ac_tran_plots_01.jpg

Am I doing something very wrong or thinking very wrong or using the software in a wrong manner here?
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Old 25th July 2021, 02:03 PM   #2965
jan.didden is offline jan.didden  Europe
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I can't see anything wrong here. The freq. response looks good and the time waveform looks fine too.
What is the problem you see? What is the level of test voltage you specified for the .ac?

Jan
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Old 25th July 2021, 02:04 PM   #2966
madis64 is offline madis64  Estonia
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Quote:
Originally Posted by jan.didden View Post
What is the problem you see?
240V as output on ac simulation plot seems strange.
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Old 25th July 2021, 02:17 PM   #2967
jan.didden is offline jan.didden  Europe
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Depends on the test voltage value you specified. If you change the scale to dB, does it look more like you would expect?
(Move the cursor in the scale area until it changes to a scale, right click, change to log).

Jan

Last edited by jan.didden; 25th July 2021 at 02:20 PM.
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Old 25th July 2021, 02:34 PM   #2968
madis64 is offline madis64  Estonia
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The simulation command is from the original file:
Pioneer_A80_ac_tran_plots_02.jpg

and ac voltage for input seems to be set to 1V.

Power line for output stage is 60V:
Pioneer_A80_ac_tran_plots_03.jpg

Result in db:
Pioneer_A80_ac_tran_plots_04.jpg

, same converted (in plot window) to V:
Pioneer_A80_ac_tran_plots_05.jpg

How can 240V output signal be obtained from +/-60V power rails?
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Old 25th July 2021, 03:58 PM   #2969
jan.didden is offline jan.didden  Europe
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.ac doesn't look at the actual circuit level capabilities. It simulates with the devices linearized around the DC point, really a very small signal, and the .ac level specified in the command is only used to set the scales of the graph.

240V if you set the .ac at 1V only tells you that the gain is 240x, about 48dB. What is the gain of the amp?

You set the test signal level for graphing in the top right corner see attachment.

Jan
Attached Images
File Type: png ac.PNG (27.1 KB, 52 views)

Last edited by jan.didden; 25th July 2021 at 04:08 PM.
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Old 25th July 2021, 04:16 PM   #2970
madis64 is offline madis64  Estonia
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Quote:
Originally Posted by jan.didden View Post
.ac doesn't look at the actual circuit level capabilities. It simulates with the devices linearized around the DC point, really a very small signal, and the .ac level specified in the command is only used to set the scales of the graph.
Ok, starts to make sense. So to have realistic values in amplifier ac analysis one should adjust the ac signal level so that the output voltage more or less matches the device actual (or designed) levels?

Regarding the gain of the amplifier - cannot tell, I just took the model from Mooly's package.
But technical specs are given for input sensitivity 150mV, power rails for output transistors seem to be around +/-60V.
Transient simulation shows that 150mV input corresponds to 35V output (P2P). Clipping (in the simulation) starts around 240mV input signal.
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