Anybody build John Broskie's enhanced version of Rosenblit's T8 OTL? Find it here:
http://www.tubecad.com/articles_2001/totem-pole_output_stage_psrr/page18.html
What I'd like to do is replace the EL509 with something I have on hand, like 6KV6. I'm hoping someone out there has the technical knowledge and the generosity of their time to explain how I would go about modifying circuit values for a different output tube. Thanks for any input on this.
http://www.tubecad.com/articles_2001/totem-pole_output_stage_psrr/page18.html
What I'd like to do is replace the EL509 with something I have on hand, like 6KV6. I'm hoping someone out there has the technical knowledge and the generosity of their time to explain how I would go about modifying circuit values for a different output tube. Thanks for any input on this.
Don't have any info on swaping power tubes, or about Tube Cads version other than the obvious question: did he actually build an "enhanced" circuit, or is it on paper only? This was a hot topic on the Transcendent forum a few years back. I built Rosenblit's T8 & it's a fine amp the way it is.
Attachments
I've seen the schematic on The Internet somewhere, but I'm not about to post it. I think the idea is to buy Rosenblit's book "Audio Reality" available on the Transcendent Sound web site. It has the schematic & test procedure for the T8 as well as other stuff. The only mod I would do is add the chokes (low noise mod) to the power supply.
Please forgive me if I came across as impolite, I didn't mean to be.
Tube Cad used to have Rosenblit's T8 amplifier circuit with all the values, without the power supply, on his web site several years ago, maybe it's still there?
I'm not going to post it because it's a patented circuit & maybe considered intellectual property.
Tube Cad used to have Rosenblit's T8 amplifier circuit with all the values, without the power supply, on his web site several years ago, maybe it's still there?
I'm not going to post it because it's a patented circuit & maybe considered intellectual property.
5u4
I don't understand why you say "I'm not going to post it because it's a patented circuit & maybe considered intellectual property."
Well let's consider intellectual property:
Anything patented is by definition publicaly available, in the patent. The patent would only prevent commercialization of it.
Of course the schematic as published in a book is covered by the same copyright as book, but even then quoting small parts of copyrighted material is generally OK by virtue of "fair use" of the material.
If someone else has published it on the net where is the law that says one cannot point a link to it? That is not copying or publishing in anyway.
Might not be a good idea to use the same name if you want to manufacture someone else design for sale, that may violate a Trade Mark but that is not the case here.
If it was a trade secret, which it is not by virtue of being in the book, it is out of the bag anyway.
Basically "intellectual property" is a meaningless term. It is a broad brush covering patents, copyrights and trade marks and one should consider ones rights under each of those laws.
Me, I'd just post the link.
I don't understand why you say "I'm not going to post it because it's a patented circuit & maybe considered intellectual property."
Well let's consider intellectual property:
Anything patented is by definition publicaly available, in the patent. The patent would only prevent commercialization of it.
Of course the schematic as published in a book is covered by the same copyright as book, but even then quoting small parts of copyrighted material is generally OK by virtue of "fair use" of the material.
If someone else has published it on the net where is the law that says one cannot point a link to it? That is not copying or publishing in anyway.
Might not be a good idea to use the same name if you want to manufacture someone else design for sale, that may violate a Trade Mark but that is not the case here.
If it was a trade secret, which it is not by virtue of being in the book, it is out of the bag anyway.
Basically "intellectual property" is a meaningless term. It is a broad brush covering patents, copyrights and trade marks and one should consider ones rights under each of those laws.
Me, I'd just post the link.
CarleyBoy,
I don't know if this will help or not but you could pull up the original Patent #2,773,136 by J. Futterman filed July 30,1953 and issued Dec 4, 1956
References Cited in the file for this patent are as follows:
2,160,788 Riddle May 30, 1939
2,358428 White Sept 19, 1944
2,383,867 Koch Aug 28, 1945
2,428,295 Scantlebury Sept 30, 1947
2,659,775 Coulter Nov 17,1953
Looks like there is an article in the AudioXPress April of 2001
Maybe one could purchase a back copy.
I don't know if this will help or not but you could pull up the original Patent #2,773,136 by J. Futterman filed July 30,1953 and issued Dec 4, 1956
References Cited in the file for this patent are as follows:
2,160,788 Riddle May 30, 1939
2,358428 White Sept 19, 1944
2,383,867 Koch Aug 28, 1945
2,428,295 Scantlebury Sept 30, 1947
2,659,775 Coulter Nov 17,1953
Looks like there is an article in the AudioXPress April of 2001
Maybe one could purchase a back copy.
A lot of feathers flying around here.
The reason I don't file patents:
1) I am comfortable with myself... I don't need a big truck. And, I won't get the Nobel Prize anyway...
2) I don't want the rest of the world to know my secrets.
Processes and chemistry is where the real strength lies in patents these days. Topology patents grow weaker by the minute... so should they.
If someone has a schem... just PM it for crying out loud. After all, WHERE did YOU get it?
The reason I don't file patents:
1) I am comfortable with myself... I don't need a big truck. And, I won't get the Nobel Prize anyway...
2) I don't want the rest of the world to know my secrets.
Processes and chemistry is where the real strength lies in patents these days. Topology patents grow weaker by the minute... so should they.
If someone has a schem... just PM it for crying out loud. After all, WHERE did YOU get it?
Oh, for the love of... Here:
http://img204.imageshack.us/img204/8781/t8circuitkt2.gif
For what it's worth, I don't think the granting of a patent guarantees the excellence of a design. I'm basically a cheap guy by nature. EL509s are getting scarce and pricey. If I could modify the circuit for a different tube that I have on hand, I'd do it. I've got 6KV6s I'd like to try. Maybe someone else has other tubes. It's the knowledge I'm after. I think in this case it might just be the grid and cathode resistors values. I just don't know how to translate tube characteristics into circuit values.
Knowing the history of BR's responses to tube substitution questons in his products on the Transcendent message board, I thought I'd have more luck here.
http://img204.imageshack.us/img204/8781/t8circuitkt2.gif
For what it's worth, I don't think the granting of a patent guarantees the excellence of a design. I'm basically a cheap guy by nature. EL509s are getting scarce and pricey. If I could modify the circuit for a different tube that I have on hand, I'd do it. I've got 6KV6s I'd like to try. Maybe someone else has other tubes. It's the knowledge I'm after. I think in this case it might just be the grid and cathode resistors values. I just don't know how to translate tube characteristics into circuit values.
Knowing the history of BR's responses to tube substitution questons in his products on the Transcendent message board, I thought I'd have more luck here.
I would think the main concern would be the bias voltage.
The purpose of the 100k grid stoppers are to isolate each tube in case of a grid short.
Don't know of any reason to change the value of the 30K grid to bias resistors for a 6KV6 or due to the different driver...... or the 170V...... or the screen resistors. Perhaps one of the EE's will help out here.
The 2 ohm cathode resistors are to help prevent a tube from hogging current.
Perhaps you already know all this. If you do I appologize, just trying to help.
The purpose of the 100k grid stoppers are to isolate each tube in case of a grid short.
Don't know of any reason to change the value of the 30K grid to bias resistors for a 6KV6 or due to the different driver...... or the 170V...... or the screen resistors. Perhaps one of the EE's will help out here.
The 2 ohm cathode resistors are to help prevent a tube from hogging current.
Perhaps you already know all this. If you do I appologize, just trying to help.
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