Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Everything Else Anything related to audio / video / electronics etc) BUT remember- we have many new forums where your thread may now fit! .... Parts, Equipment & Tools, Construction Tips, Software Tools......

Spice Empire
Spice Empire
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Thread Tools Search this Thread
Old 8th November 2002, 02:04 PM   #1
stadams is offline stadams
diyAudio Member
Join Date: Mar 2002
Location: South MS
Default I hold at your neck the gom jabbar.


Is your attached picture implying that this is a painful discussion? Or possibly that only in the "Empire" does the "Spice" clarify issues through heightened sensitivity and prescience whilst in our world of electronics it seems to muddle and confound even the simplest of explainations?

  Reply With Quote
Old 8th November 2002, 02:11 PM   #2
Jiiim is offline Jiiim
diyAudio Member
Jiiim's Avatar
Join Date: Aug 2002
Location: England
Default English expression

There is an expression in England which goes along the lines of:

"Only a bad workman blames his tools".

  Reply With Quote
Old 8th November 2002, 02:17 PM   #3
jam is offline jam  United States
diyAudio Member
jam's Avatar
Join Date: May 2001
Location: Auburn, CA, USA
What do you say to the above, Harry! .....Er. I mean Fred.

  Reply With Quote
Old 8th November 2002, 02:54 PM   #4
Christer is offline Christer  Sweden
diyAudio Member
Join Date: Sep 2002
Location: Sweden
One big problem with Spice is, as Fred points out, is that the
transistor models are not very good. I have looked at a number
of manufacturers models of BJTs and none of them correlate
well with the data sheets. I have DIYed models for some BJTs
and I cannot find any way to make them correlate well to the
data sheets, getting about the same problems as the
manufacturers models have.

I am sure one can improve on the simulations by learning more
about how Spice works, tweaking the simulation parameters.
however, no simulation is better than its models, and this is
a weak link in the chain. The models can still work fine in many
cases, if you make sure that the transistors operate under the
conditions where the models are OK.

As for distorsion measurements, I have run a number of
large-signal analyses on some amps and FFt'd to get a
spectrum. I do not assume that this gives distorsion figures
that coincide with the real circuit. However, I think it can give
a good idea of the relative performance of two circuits. What
happens to the distorsion if I change a particular resistor value?
Which has the lower distorsion of two similar circuits? I think
even the relative change of even vs. odd order distorsion may
tell some truth.

All of us do not have spectrum analyzers or the time and money
to build hundreds of different amps. I think Spice can give some
help to choose what to build, but it cannot tell you how an amp
will sound of course (at least not without a lot of experience at
correlating real amps with Spice results).
  Reply With Quote
Old 8th November 2002, 03:35 PM   #5
mlloyd1 is offline mlloyd1  United States
diyAudio Member
mlloyd1's Avatar
Join Date: Feb 2001
Location: Northern Iliinois
I think the various simulators are NOT useful at all for determining actual distortion numbers, but can be VERY useful (when properly applied) for seeing effects of changes in a relative fashion.

The trick is "properly applied" implies some learning/understanding that takes a bit of time and practice to acquire.

  Reply With Quote
Old 8th November 2002, 03:41 PM   #6
Jocko Homo is offline Jocko Homo  United States
Join Date: Feb 2002
Location: As far from the NOSsers as possible
Default Thanks to Christer......

and yes......Phred. And I see my ol' buddy up north just jumped in.

Go read Bob Pease's book. Phred and I are not the only engineers out there that know better than believe the gibberish that Spice can spit out.

Yes, you have to know how to ask it the right question. You also have to be smart enough to know when it gives you the wrong answer. Something us old-timers learned how to do in the days before everyone started using, and believing, it without questioning it.

Now.....I want to see you argue with Bob Pease. That would be highly entertaining. I think we would all be amused by that.

  Reply With Quote
Old 8th November 2002, 03:49 PM   #7
fdegrove is offline fdegrove  Europe
diyAudio Senior Member
fdegrove's Avatar
Join Date: Aug 2002
Location: Belgium


Phred and I are not the only engineers out there that know better than believe the gibberish that Spice can spit out.
And I wouldn't even rely on the output of a simple spreadsheet as some MD's do oh sooo religiously.

If it looks a bit odd than check it out the old fashioned way and soon enough you realize something doesn't compute.

Now I'll have that glass of Claret,
  Reply With Quote
Old 8th November 2002, 06:12 PM   #8
Fred Dieckmann is offline Fred Dieckmann  United States
diyAudio Retiree
Join Date: Oct 2002
Location: Spain or the pueblo of Los Angeles
Default He who controls the Spice Controls the Universe

Folding space to travel without moving........ and now running Spice to design without measuring.

Again I say..... check your simulations against some real measured numbers.


I have used Spice since 1976 by the way. This was with punch cards and the school's (UofA, Fayetteville Arkansas) IBM 360! The first serious assignment was to design a single transistor amplifier with Spice. I proved that Hfe variations made a single transistor circuit a poor choice for the stated. This would have required measurements on a large group of transistors with sufficient Hfe spread. Spice is a wonderful tool.

A pair 6 inch Vise-Grip pliers is great tool, but I wouldn't try to hammer a nail with them.

The spice must flow,

PS Low distortion oscillators are pretty easy to build with an op amp and a light bulb. Aa sound card and a shareware FFT program makes distortion pretty easy to measure. You don't have to buy a bunch of expensive equipment to make good distortion measurements.
Attached Images
File Type: jpg guild_navigator.jpg (25.0 KB, 453 views)
  Reply With Quote
Old 8th November 2002, 08:00 PM   #9
Jocko Homo is offline Jocko Homo  United States
Join Date: Feb 2002
Location: As far from the NOSsers as possible
I've used a 6" pair of vise grips for a hammer. Sometimes ya gotta use wots ya got.

But only if I had to...........

  Reply With Quote
Old 8th November 2002, 08:15 PM   #10
Pjotr is offline Pjotr
diyAudio Member
Pjotr's Avatar
Join Date: Nov 2002
Location: Netherlands
Ok Fred, but what has these to do with the I/V converter the topic is about

Funny to see some old wise men hanging around here that seem to be arrived in DIY-audio heaven. Knowing all there is to know and in the end only be able to give their opinion by one-liners without proper reasoning and making no sense concerning the topic. Everywhere they appear in a topic, the topic gets lost in space.

Go ahead fellows, amuse yourself by spitting around your frustrations. I will go back to the music itself. There are funnier places to be.

Maybe later…

Click the image to open in full size.
  Reply With Quote


Spice EmpireHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Empire 400TC PTSOUNDLAB Analogue Source 1 10th February 2017 05:15 PM
Empire Turntable FS flocchini Swap Meet 1 30th March 2009 09:26 PM
My empire TT project randytsuch Analogue Source 2 3rd September 2005 09:10 PM
Empire 900? Zen Mod Analogue Source 0 2nd July 2005 11:06 PM
Empire 208 needs? tmaull Analogue Source 0 11th June 2005 07:33 AM

New To Site? Need Help?

All times are GMT. The time now is 10:29 PM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.79%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright ©1999-2017 diyAudio