"
From the latest LTspice "junkie" , I confirm that a modeled
amp works pretty close to the simulated one. The only thing
left to deal with is thermal issues and layout considerations.
OS
From the latest LTspice "junkie" , I confirm that a modeled
amp works pretty close to the simulated one. The only thing
left to deal with is thermal issues and layout considerations.
OS
cant you set device temperatures before a simulation? or is this not a practical way to test temperature dependance?
I just set the values of a "real world" amp (frugal 1)for the Vbias
components and hope that the simulation performs well.
I would assume most tranny models are created at room temp.
Also, In a simulation, only the OP's/ drivers/Vbias have a
temp. variable.(VAS is higher, but constant)
For my VAS a little trick I just started using is to change
the beta variable in the .model file to reflect the "real world"
For example, my MJE 350's show a 10% gain at 30+C,
so I increase this in the model to reflect the actual circuit.
As discussed earlier in this thread I would assume that
actually testing real world components to build your
own models would be the only way to insure better
accuracy.
OS
components and hope that the simulation performs well.
I would assume most tranny models are created at room temp.
Also, In a simulation, only the OP's/ drivers/Vbias have a
temp. variable.(VAS is higher, but constant)
For my VAS a little trick I just started using is to change
the beta variable in the .model file to reflect the "real world"
For example, my MJE 350's show a 10% gain at 30+C,
so I increase this in the model to reflect the actual circuit.
As discussed earlier in this thread I would assume that
actually testing real world components to build your
own models would be the only way to insure better
accuracy.
OS
cbdb said:
Yes you can set temperature before a simulation, however it is not as simple as it sounds. It is very unlikely that every component will be at the same temperature so you need to have an idea what the operating temp is for each part. For something like a preamp you could probably come close. For an amplifier the temp of most components varies considerably with output power. If you can design the circuit, not just copy one, then you can get pretty close but it is a lot of work.
Now all you have to do is have an accurate idea of the ambient temp where the circuit will be used, to what degree is the chassis ventilated, what heat sink you will use and a whole bunch of little things. I have found it easier to get accurate results by using thermocouples on a built project. If you change something you do it over. Of course you can just build and sell and hope for the best, but I wouldent plan a business that way.
Steve
SPICE FOR TECHNICIANS
Hi,
Im a tech.I have never used spice. Would it be helpful for troubleshooting audio? For example, could a schematic be fed into SPICE and analyzed?
Great forum.
Thanks.
Hi,
Im a tech.I have never used spice. Would it be helpful for troubleshooting audio? For example, could a schematic be fed into SPICE and analyzed?
Great forum.
Thanks.
Re: SPICE FOR TECHNICIANS
Yes, for sure. A schematic can be entered into SPICE and analyzed for dc operating points, ac frequency response and stability, and transient response, just for starters. The caveat is that you have decent models for the transistors used. However, even sloppy models can lend insight into how the design is supposed to work.
Cheers,
Bob
saj888 said:
Yes, for sure. A schematic can be entered into SPICE and analyzed for dc operating points, ac frequency response and stability, and transient response, just for starters. The caveat is that you have decent models for the transistors used. However, even sloppy models can lend insight into how the design is supposed to work.
Cheers,
Bob
Has any tech ever used SPICE for everyday shop repairs on audio?
Pro audio especially. Power amps, Mixing boards, Crossovers, Eqs etc.
Thanks.
Pro audio especially. Power amps, Mixing boards, Crossovers, Eqs etc.
Thanks.
The reason I have never been interested in SPICE its because most of what I have read on the net about it is from experimenters who just seems to be doing electronics as a hobby. Nothing concrete that would benefit techs who who like me who repair over 20 pieces of pro audio every week. Average 12 amps a week for over 15 years.
Most of what I have seen on the net is for amateurs and non professionals.
Most of what I have seen on the net is for amateurs and non professionals.
I have a strong feeling you might be right!
D, I dont often come across a tech who is into a lot of pro audio repairs. Maybe we could communicate directly by email and assist one another directly. Or through this same forum, so it would benefit others. CROWN, QSC, CREST, NUMARK, RANE, ASHLY, ALLEN AND HEATH, YAMAHA, ETC, ETC ETC, EVEN OLD SCHOOL LIKE MC INTOSH, DYNACO, ROTEL, KENWOOD PIONEER, SANSUI ETC, ETC. i could go on and on. You name it. I have repaired thousands.
Keep in touch.
D, I dont often come across a tech who is into a lot of pro audio repairs. Maybe we could communicate directly by email and assist one another directly. Or through this same forum, so it would benefit others. CROWN, QSC, CREST, NUMARK, RANE, ASHLY, ALLEN AND HEATH, YAMAHA, ETC, ETC ETC, EVEN OLD SCHOOL LIKE MC INTOSH, DYNACO, ROTEL, KENWOOD PIONEER, SANSUI ETC, ETC. i could go on and on. You name it. I have repaired thousands.
Keep in touch.
With the amount of time it takes to input the cct. into spice unless your stuck it would be quicker to use the service manual.
EKV in VDMOS
Here is what I want for Christmas:
An EKV model inside LTspice VDMOS as an option.
Maybe we can get Mike Engelhardt to play Santa for us.
Ho, Ho Ho,
Bob
Here is what I want for Christmas:
An EKV model inside LTspice VDMOS as an option.
Maybe we can get Mike Engelhardt to play Santa for us.
Ho, Ho Ho,
Bob
I would just like a good SPICE program.
Can anyone steer me towards a good package(or is there one program that does it all)? I have only used SPICE on a mac, with a program (MI-Sugar) that took cct diagrams and output graphs (it also lets you use other models). It works quite well but was never really finished. Also tried MacSpice but cant bare inputing text. I now have access to a PC and would like to use that for SPICE. Would also like to spend as little as possible, but am willing to pay(or ask Santa).
Thanks in advance.
Chester
Can anyone steer me towards a good package(or is there one program that does it all)? I have only used SPICE on a mac, with a program (MI-Sugar) that took cct diagrams and output graphs (it also lets you use other models). It works quite well but was never really finished. Also tried MacSpice but cant bare inputing text. I now have access to a PC and would like to use that for SPICE. Would also like to spend as little as possible, but am willing to pay(or ask Santa).
Thanks in advance.
Chester
LTspice IV is free http://www.linear.com/designtools/software/, everyone around here using it,it is huge, complex for novice, but you can get support at yahoo LTspice group http://groups.yahoo.com/group/LTspice/ as well as at this thread...I love it.🙂
Just checked LTspice out, Looks great. Not knew to spice, but still a bit of a learning curve, especially for running sims and outputing data.
You just made my Xmass merrier, leaving tommorow on a week road trip to visit the inlaws and now I have a great distraction(taking the laptop).
Thanks again and a Happy Holidays to all, talk to you in the new year (Im sure Ill have questions)! :frosty
You just made my Xmass merrier, leaving tommorow on a week road trip to visit the inlaws and now I have a great distraction(taking the laptop).
Thanks again and a Happy Holidays to all, talk to you in the new year (Im sure Ill have questions)! :frosty
I just let my ~400 day old version of LT spice run a "sync release" update (about 5 Meg).
After all that the program doesn't appear to be any different, with the exception of the error message attached, which appears each time the program is run.
Anyone have any idea what this means?
After all that the program doesn't appear to be any different, with the exception of the error message attached, which appears each time the program is run.
Anyone have any idea what this means?
