Re: Re: Re: Re: Re: Re: Re: LT1166
I can't believe you don't understand what comparing two circuits means: schematics, results, numbers (even by simulation). Everything else is personal bias BS.
I don't have your P about (and, if you don't want or can't post it here, I don't intend to spend a penny on that) so I can't RTF.
I have your WW paper on bias and it doesn't tell squat about LT1166 other than blank statements as above.
Edmond Stuart said:
I can't believe you don't understand what comparing two circuits means: schematics, results, numbers (even by simulation). Everything else is personal bias BS.
I don't have your P about (and, if you don't want or can't post it here, I don't intend to spend a penny on that) so I can't RTF.
I have your WW paper on bias and it doesn't tell squat about LT1166 other than blank statements as above.
Would you please stop whining about irrelevant details.
Nobody is interested in your personal biased BS (your words).
BTW, I'm still waiting for your H(s) function for the NFB-OPS. Perhaps too difficult?
Nobody is interested in your personal biased BS (your words).
BTW, I'm still waiting for your H(s) function for the NFB-OPS. Perhaps too difficult?
Re: Re: Re: Re: Re: Re: Re: LT1166
Hi Edmond,
Your assumptions were wrong. I never heard of D2S and still don't know what it stands for. Maybe I will after I read the article.
In the meantime, it appears that you have not done much with the LT1166, and apparently not built anything with it. You need to think a little more out of the box in regard to using and understanding the LT1166. Read the app notes carefully, then just think of using it purely as a dynamic bias spreader.
Cheers,
Bob
Edmond Stuart said:
Hi Edmond,
Your assumptions were wrong. I never heard of D2S and still don't know what it stands for. Maybe I will after I read the article.
In the meantime, it appears that you have not done much with the LT1166, and apparently not built anything with it. You need to think a little more out of the box in regard to using and understanding the LT1166. Read the app notes carefully, then just think of using it purely as a dynamic bias spreader.
Cheers,
Bob
D2S means difference of two squares, a concept proposed by Ian Hegglun to minimize power MOSFET transfer function nonlinearity.
Re: Re: Re: Re: Re: Re: Re: Re: LT1166
Hi Bob,
True, I've never built anything with it. And I've no intention to do that. Understanding the LT1166... don't worry, I did read all the app notes and I fully understand the underlying principles, i.e holding the product of source currents at a constant level, or -using your words- see it as a dynamic bias spreader. I did just that.
I've simulated dozens of circuits based on this principle, but in all cases, holding the bias spreader at a fixed (but temperature dependent) value gives better results. Okay, not that much, but, together with the caveats of an additional loop, enough reason to stop further investigations into this chip and its applications.
BTW, do you know why this chip has a slight positive tempco? (see below) Is it a feature or a flaw?
Cheers, Edmond.
Bob Cordell said:
Hi Bob,
True, I've never built anything with it. And I've no intention to do that. Understanding the LT1166... don't worry, I did read all the app notes and I fully understand the underlying principles, i.e holding the product of source currents at a constant level, or -using your words- see it as a dynamic bias spreader. I did just that.
I've simulated dozens of circuits based on this principle, but in all cases, holding the bias spreader at a fixed (but temperature dependent) value gives better results. Okay, not that much, but, together with the caveats of an additional loop, enough reason to stop further investigations into this chip and its applications.
BTW, do you know why this chip has a slight positive tempco? (see below) Is it a feature or a flaw?
Cheers, Edmond.
Attachments
Re: Re: Re: Re: Re: Re: Re: Re: Re: LT1166
In your readings, apparently you missed the device synopsis. Nobody said this IC is "better" (AC performance wise) than a fixed bias spreader. However, this IC solves very real practical problems, outlined in the circuit description:
- Eliminates Adjustments
- Eliminates Thermal Runaway of IQ
- Corrects for Device Mismatch
- Simplifies Heat Sinking
- Programmable Current Limit
All these for $2 and with a minimal AC performance impact. Of course, all of the above are non-issues in simulations.
Edmond Stuart said:
In your readings, apparently you missed the device synopsis. Nobody said this IC is "better" (AC performance wise) than a fixed bias spreader. However, this IC solves very real practical problems, outlined in the circuit description:
- Eliminates Adjustments
- Eliminates Thermal Runaway of IQ
- Corrects for Device Mismatch
- Simplifies Heat Sinking
- Programmable Current Limit
All these for $2 and with a minimal AC performance impact. Of course, all of the above are non-issues in simulations.
Re: Re: Re: Re: Re: Re: Re: Re: Re: Re: Re: LT1166
Because of this:
http://www.diyaudio.com/forums/showthread.php?postid=1478092#post1478092
Quote: "Perhaps I wouldn't recommend this solution for the ultimate performance (where cost and complexity are non-issues)<snip>"
I have published some preliminary results on an LT1166 + LM4702 + power bipolars based amp, 14 months ago, on this forum. This solution is the foundation for my current 7x home HT amp - and I'm very happy with.
Edmond Stuart said:
Because of this:
http://www.diyaudio.com/forums/showthread.php?postid=1478092#post1478092
Quote: "Perhaps I wouldn't recommend this solution for the ultimate performance (where cost and complexity are non-issues)<snip>"
I have published some preliminary results on an LT1166 + LM4702 + power bipolars based amp, 14 months ago, on this forum. This solution is the foundation for my current 7x home HT amp - and I'm very happy with.
Re: Re: LT1166
Under 0.01% THD20 and about the same for IMD 19+20. To me, its not bad for a $30/channel 100W amp (in parts and PCB). All measured in the case with tghe lid on. The amp is actually 5x2 channels configurable for independent, bridge or multi-amping.
I'll post some pictures next time I'll pull it from the rack and pop the lid. The final schematic could be also slightly different.
Don't bother, there are no models for the LM4702. You may better use your time in designing the 4 layer PCB for your PMP amp. I'm sure you'll have fun building it and don't forget to enlighten us with some THD and IMD measurement results.
Edit: $30/two channels!
Edmond Stuart said:
Under 0.01% THD20 and about the same for IMD 19+20. To me, its not bad for a $30/channel 100W amp (in parts and PCB). All measured in the case with tghe lid on. The amp is actually 5x2 channels configurable for independent, bridge or multi-amping.
I'll post some pictures next time I'll pull it from the rack and pop the lid. The final schematic could be also slightly different.
Don't bother, there are no models for the LM4702. You may better use your time in designing the 4 layer PCB for your PMP amp. I'm sure you'll have fun building it and don't forget to enlighten us with some THD and IMD measurement results.
Edit: $30/two channels!
Re: Re: Re: Re: Re: Re: Re: Re: Re: Re: LT1166
Well put.
It does not just prevent thermal runaway, but also reduces the impact of fast-changing junction temperatures under program conditions that can lead to an output stage being way sub-optimally biased on a dynamic basis.
When properly used without dependence on its through amplification path, I don't think it compromizes fidelity at all.
Cheers,
Bob
syn08 said:
Well put.
It does not just prevent thermal runaway, but also reduces the impact of fast-changing junction temperatures under program conditions that can lead to an output stage being way sub-optimally biased on a dynamic basis.
When properly used without dependence on its through amplification path, I don't think it compromizes fidelity at all.
Cheers,
Bob
Re: LT1166
Indeed, when properly used .......... Do you know how?
edit PS: Any idea of the tempco of this chip.
Bob Cordell said:
Indeed, when properly used .......... Do you know how?
edit PS: Any idea of the tempco of this chip.
Re: Re: Re: LT1166
So that's a real PMP amp. I'm afraid of having to change the name of my little baby. Any suggestion? Perhaps pseudo poor man's power amp (PPMP).
syn08 said:
So that's a real PMP amp. I'm afraid of having to change the name of my little baby. Any suggestion? Perhaps pseudo poor man's power amp (PPMP).
PMA said:
Normally, people call me Edmond. Egmont was an earl and slightly more famous than me
, as you probably know.Cheers.