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Old 6th February 2013, 01:32 PM   #31
generg is online now generg  Germany
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Thank you Semisouthfan for your further explanations to work with less appropriate DMMs......I will report success!
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Old 6th February 2013, 04:00 PM   #32
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Originally Posted by Semisouthfan View Post
Yep, that devilish OAP (one atmospheric pressure) glow discharge in air will fill a room with O3 if you aren't careful. The well known "Hill Type 1" fixed this problem using Helium. "Fixed," that is, if you think re-ordering a bottle of helium to keep your tweeter running is practical.

But helium, besides controlling the O3, has another crucial advantage. If you read my paper, you'll see what I mean.

My paper was inspired by Alan Hill, whom I had the pleasure of meeting in person and talking plasma speakers with way back when. He told me to look up his patent. I did. It was amazing and the paper I wrote was based on a derivation that he published in the patent. (Most unusual...)
I apologize for digressing from the theme. I'll read your paper. The patent by Hill is US 4,219,705. May I introduce you to another Beast. It is an amp by Mr. Pass which he named the "Beast with a Thousand Jfets". Please visit www.firstwatt.com which has its attendant DIY article. Mr. Pass has a large following of students [DIYers] who have built his offering of DIY amps and will continue to do so for years to come. Except; the Jfets used in his Beast are becoming rare and may have the production status of EOL. DIYers would love to get their hands on low cost and equivalent Jfets. I hope that you, and your Industrial position [Co-founder of SemiSouth] can help DIYers with find such fresh supplies. Also, please visit the Thread in the Pass Labs Forum which is entitled " Article: Beast with a Thousand Jfets" for ongoing dialog.

Best regards.
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Old 6th February 2013, 04:11 PM   #33
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Originally Posted by jackinnj View Post
Did SemiSouth tank as it was "sole-source"?
The short answer is "no." While that was an issue that came up with some customers, the company was achieving it's goals for large accounts for the SiC transistor. Sales was not the problem. The failure of the company was due to a complex set of factors including operations and financing.
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Old 6th February 2013, 04:30 PM   #34
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Originally Posted by Antoinel View Post
I apologize for digressing from the theme. I'll read your paper. The patent by Hill is US 4,219,705. May I introduce you to another Beast. It is an amp by Mr. Pass which he named the "Beast with a Thousand Jfets". Please visit www.firstwatt.com which has its attendant DIY article. Mr. Pass has a large following of students [DIYers] who have built his offering of DIY amps and will continue to do so for years to come. Except; the Jfets used in his Beast are becoming rare and may have the production status of EOL. DIYers would love to get their hands on low cost and equivalent Jfets. I hope that you, and your Industrial position [Co-founder of SemiSouth] can help DIYers with find such fresh supplies. Also, please visit the Thread in the Pass Labs Forum which is entitled " Article: Beast with a Thousand Jfets" for ongoing dialog.

Best regards.
Thank you Antoinel for your confidence in me.

As you know from my article "Is it a SemiSouth?", I referenced Nelson Pass' Beast paper. I am sufficiently connected to the rest of the SiC transistor community to have an idea of what is coming. I am seeking access to a few parts to see if they have the "right stuff" to be an alternative to the SemiSouth JFET. But the first question that should be asked is, what is it about a SemiSouth JFET that makes it deliver the performance that you and your fellow DIY mates seek? I promise, I have put some thought to that question, originally inspired by Nelson's writings and suggestions on the topic.

As a result, my next article will be a two part discussion on the connection between the terminal properties of a SemiSouth JFET and the circuit performance that audiophiles seek. I will include "DIY Audio" friendly methods for analyzing that connection that I use myself because, frankly, I am no expert in audio amplifier design.
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Old 6th February 2013, 05:12 PM   #35
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Thank you Dr. Mazzola for replying, and for your correction above which follows from your article. " Thus, every R100 is an example of a “massively parallel” JFET assembly long before Nelson Pass used the term in his latest article “The Beast with a Thousand JFETs” (see http://firstwatt.com/articles.html)."


I look forward to your future articles. Your writing style is clear, educational and entertaining.

Best regards.

Last edited by Antoinel; 6th February 2013 at 05:25 PM.
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Old 6th February 2013, 06:33 PM   #36
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In that regard: Refrences to the Vds vs. Ids from N.P. elude to a triode like behaviour, along with lower Drain impeadance, seem most important and confusing to me. Manipulating the load line to attempt to operate in the most linear region, as triode tube circuits can easily do, see FIRST WATT the F3(or the Zen V9), is understandable but not obtainable in semiconductors so easily. I'm thinking the lower Vds, like the LU1014 part has, can get us closer to that linear transfer curve in your parts also, albeit nwith maybe 6 or 8V? and with loadline canceling performance while deviating from that ideal operating point. This likely would involve cascoding the device but we are fearless DIYers. I live in the New England, electricity is still cheaper than oil. He has also eluded to the 085 device having promise in this rergard also with even lower drain resistance.
Additionally, the input load the signal source sees is a major distortion causing functoin due to the rediculous C curve rising with lower Vds below 50V.
I would think you have all the access you need to papa to learn more of the details. I would bet since you are helping the DIY community so much he would be happy to give you all he knows to help. Give him a call
I should try to find an affordablbe curve tracer myself, 675 was it?
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Old 6th February 2013, 08:33 PM   #37
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Dr. Mazzola; Mr./Dr. Casady and yourself have joint US patents regarding ICs made with/on SiC which date back to 2002. Is R100 and its manufacture patent-protected? In your article, "Is It a SemiSouth?" of post #2, you dwelled on the possibility of an illegitimate; but functional copy of R100. Thus, your simple and effective test method may not differentiate between them. The ultimate acid test for the DIYer is to drop the devices in an F6 DIY amp. If the impostor device is an NPN BJT, the amp will not speak [or sing softly] because the bias and signal drives [for the base-emitter circuit] are inadequately low. The DIYer and equipment are protected from physical harm. But; if the devices are JFETs, how will a DIYer tell whether they are authentic or copies from the performance of the diy F6 amplifier? This question may be important for some and irrelevant to others.

Best regards
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Old 6th February 2013, 08:47 PM   #38
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Looking forward to reading more...
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Old 6th February 2013, 09:44 PM   #39
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Originally Posted by flg View Post
In that regard: Refrences to the Vds vs. Ids from N.P. elude to a triode like behaviour, along with lower Drain impeadance, seem most important and confusing to me. Manipulating the load line to attempt to operate in the most linear region, as triode tube circuits can easily do, see FIRST WATT the F3(or the Zen V9), is understandable but not obtainable in semiconductors so easily. I'm thinking the lower Vds, like the LU1014 part has, can get us closer to that linear transfer curve in your parts also, albeit nwith maybe 6 or 8V? and with loadline canceling performance while deviating from that ideal operating point. This likely would involve cascoding the device but we are fearless DIYers. I live in the New England, electricity is still cheaper than oil. He has also eluded to the 085 device having promise in this rergard also with even lower drain resistance.
Additionally, the input load the signal source sees is a major distortion causing functoin due to the rediculous C curve rising with lower Vds below 50V.
I would think you have all the access you need to papa to learn more of the details. I would bet since you are helping the DIY community so much he would be happy to give you all he knows to help. Give him a call
I should try to find an affordablbe curve tracer myself, 675 was it?
Quote:
Originally Posted by Antoinel View Post
Dr. Mazzola; Mr./Dr. Casady and yourself have joint US patents regarding ICs made with/on SiC which date back to 2002. Is R100 and its manufacture patent-protected? In your article, "Is It a SemiSouth?" of post #2, you dwelled on the possibility of an illegitimate; but functional copy of R100. Thus, your simple and effective test method may not differentiate between them. The ultimate acid test for the DIYer is to drop the devices in an F6 DIY amp. If the impostor device is an NPN BJT, the amp will not speak [or sing softly] because the bias and signal drives [for the base-emitter circuit] are inadequately low. The DIYer and equipment are protected from physical harm. But; if the devices are JFETs, how will a DIYer tell whether they are authentic or copies from the performance of the diy F6 amplifier? This question may be important for some and irrelevant to others.

Best regards
I should not be surprised that I have stimulated questions before I laid out my thoughts in a cogent article. That will teach me to post a what-I'm-going-to-do-before-I-do-it post. We'll call it testing the waters. I'm glad you all are interested. And why not? Making an amplifier "sing softly" is what you all do so well. If a SemiSouth JFET helps, then you are by definition interested. If it doesn't help, this should be a thread of one poster (me). Again, we can thank Nelson for bringing to all of us the fact of the usefulness of the SemiSouth JFET for these types of amplifiers. The question of why they are useful is what I want to write about. And in that context, my background as a practicing engineering professional and educator gives me a starting point for my thinking. But, as I said, I am not an amplifier design expert so I will be very upfront in my article to say what I am not considering in the analysis. The reader will need to evaluate this information (and point of view) in the bigger picture, and I see that process has already begun.

But to answer a couple of specific questions:
1. What we need is a simple method to capture the effects of the dependence of Id on both Vgs and Vds, and to make if feasible to allow for part to part variation so that custom models for the specific parts in your inventory can be captured and analyzed with relatively simple hardware and software tools (to include freeware Pspice and spreadsheets) that are within the reach of the DIY community. I'm fortunate to work at a large university and to be using a Tektronix 370B, the cost of which probably does not qualify as "within reach" unless you are really really serious about your DIY Audio hobby. I will cover that in my article.

2. Yes, the company would have maintained that the R100 is covered by one or more patents. I would look to U.S. Patent No. 6,767,783 as the core patent.

3. In my article, I cast doubt on the likelihood of any SiC part being passed off as a copy of a R100. I do not consider a silicon npn BJT to be a functional copy of a R100, but I will concede that a reader could interpret what I said that way. Sooo, let me say it differently: You can measure the terminal characteristics of each and every SemiSouth JFET in your inventory and prove beyond a shadow of a doubt that it is not a silicon npn BJT. A BJT is not a "copy" of a JFET, but instead it is a fake that has only superficial resemblance to a SemiSouth JFET. If you put a BJT sold as a fake R100 into an F6 I do not know if the BJT would sing well enough to get away with the fraud. Who knows? You might end up liking the BJT better than the SemiSouth JFET! After all, there are a lot of BJTs in the world and they have a significant reputation for linearity. It's an interesting thought, but an altogether different topic.
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Old 6th February 2013, 10:12 PM   #40
Zen Mod is offline Zen Mod  Serbia
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if biased ( meaning of U"gs" as SS , bjt will go to flame , or PSU , or just fuse ;

and there is no way that xformer secondaries will be happy with pulsating current , feeding hungry base


well - at least comparing with Jfet , performance will suffer
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