My precious post failed to ask the question I had intended. I have two pairs of J74, some reasons to suspect they are genuine Toshiba, each with IDSS=10.33. Assuming they will run above room temp in circuit, and that K170s will as well, is there any general propensity for the IDSS of either type to drift more? In other words, should I shoot for as close a match as possible closest to 10.33 or would higher be preferable? Or lower?
The K170s are cheaper and I have a larger pool so I have some flex here.
The K170s are cheaper and I have a larger pool so I have some flex here.
Does anyone know where to source boards for Blowtorch if they're available?
John, my congrats on the award!
Ciao!
Do
John, my congrats on the award!
Ciao!
Do
No Blowtorch boards available (unless John has a weak moment) and then there is the problem of finding the very high IDSS original devices and matching. The board was designed to use the thick aluminum chassis as heatsink and fully sealed case for EMI protection, and then thermal equalibrium that takes a while to reach. (I believe it's always powered to keep it in prime operating state).
The Blowtorch is also the sum of the board design, passive parts, the case, the silver internal wire they got from Bear, wire layout, connectors, Shalco switches, premium TKD 65 series attenuators, external power supply design etc.etc i don't imagine John wants us hackers devaluing the effort it took to design and make it, and the resale value of the roughly 40 something units in the field. (and all the questions we'll ask when get it wrong). it's John's intellectual property and how he earns a modest living and he kindly offers design and repair guidance here and often takes a ribbing or worse (especially when he remembers all of his contacts over the years). There's enough of his work on Ebay that he earns nothing on.
I hope i get a board set for this.......
The Blowtorch is also the sum of the board design, passive parts, the case, the silver internal wire they got from Bear, wire layout, connectors, Shalco switches, premium TKD 65 series attenuators, external power supply design etc.etc i don't imagine John wants us hackers devaluing the effort it took to design and make it, and the resale value of the roughly 40 something units in the field. (and all the questions we'll ask when get it wrong). it's John's intellectual property and how he earns a modest living and he kindly offers design and repair guidance here and often takes a ribbing or worse (especially when he remembers all of his contacts over the years). There's enough of his work on Ebay that he earns nothing on.
I hope i get a board set for this.......
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I'd like what he's hoping for, garcon
lemme know if you do and I'll (re)quote your entire post 🙂
lemme know if you do and I'll (re)quote your entire post 🙂
No Blowtorch boards available (unless John has a weak moment) and then there is the problem of finding the very high IDSS original devices and matching. The board was designed to use the thick aluminum chassis as heatsink and fully sealed case for EMI protection, and then thermal equalibrium that takes a while to reach. (I believe it's always powered to keep it in prime operating state).
The Blowtorch is also the sum of the board design, passive parts, the case, the internal wire, Shalco switches, TKD 65 series pots, external power supply design etc.etc i don't imagine John wants us hackers devaluing the team effort it took to design and make it. (and all the questions we'll ask when get it wrong). it's John's intellectual property and how he earns a modest living. There's enough of his work on Ebay that he earns nothing on.
The Blowtorch is also the sum of the board design, passive parts, the case, the internal wire, Shalco switches, TKD 65 series pots, external power supply design etc.etc i don't imagine John wants us hackers devaluing the team effort it took to design and make it. (and all the questions we'll ask when get it wrong). it's John's intellectual property and how he earns a modest living. There's enough of his work on Ebay that he earns nothing on.
I'm just saying... there could have been original boards he sold just like Nelson Pass.
Then I guess not...
Well, at least I have my JC-80 working for a year and they sound quite good!
Ciao!
Do
Then I guess not...
Well, at least I have my JC-80 working for a year and they sound quite good!
Ciao!
Do
Perhaps JC-80 would be a nice DIY project endorsed by John Curl.
His reaction to these eBay boards and his helping people out in this thread have been a positive surprise - he has all the reasons in the world to try and stop the sale of these boards and instead he helps out people who bought them.
But, IMHO, an "official" batch of boards (perhaps even sold on Diyaudio's Store) would be way better than helping a "clever" eBay seller get rich.
His reaction to these eBay boards and his helping people out in this thread have been a positive surprise - he has all the reasons in the world to try and stop the sale of these boards and instead he helps out people who bought them.
But, IMHO, an "official" batch of boards (perhaps even sold on Diyaudio's Store) would be way better than helping a "clever" eBay seller get rich.
Oh yes, a DIY preamp by John Curl, a DIY power amp by Nelson Pass and a DIY speaker by Joachim Gerhard ...
I am already working on it. See my ZDL thread. It was quiet for some time but it will continue.
Cool, will read the thread. I must have missing it somehow because I can´t build everything at the same time. (I´m only allowed to convert a part of the living room into a laboratory ;-) )
Let's make it happen
John has been GREAT. I was amazed when he offered to help. I would be the first customer. I currently have only a single pcb for the JC-80 and regulator anyway. I have a pristine regulator & caps pcb with the flex to allow DIY fanatics to use single or dual r-cores. I will put $100 into a project to defray iniitial pcb fixed costs as long as John gets royalties on the boards sold. We know the chinese boards work -- pinnocchio has used them. I would be a beta tester and use my parts on the first test batch of pcbs to prove them. For lack of expertise, I will not lead it.
Now for the reality. Is there demand for a quantity of these or should we reassess whether we are "helping a 'clever' eBay seller get rich" or Stanton is offering a genuinely good service for the limited volumes involved?
I do not know the answer, yet.
John has been GREAT. I was amazed when he offered to help. I would be the first customer. I currently have only a single pcb for the JC-80 and regulator anyway. I have a pristine regulator & caps pcb with the flex to allow DIY fanatics to use single or dual r-cores. I will put $100 into a project to defray iniitial pcb fixed costs as long as John gets royalties on the boards sold. We know the chinese boards work -- pinnocchio has used them. I would be a beta tester and use my parts on the first test batch of pcbs to prove them. For lack of expertise, I will not lead it.
Now for the reality. Is there demand for a quantity of these or should we reassess whether we are "helping a 'clever' eBay seller get rich" or Stanton is offering a genuinely good service for the limited volumes involved?
I do not know the answer, yet.
Hi Wolfsin,
I am totally in agreement with you on "I will put $100 into a project to defray iniitial pcb fixed costs as long as John gets royalties on the boards sold". I would too!
I would certainly buy 2-4 boards if they were available
Ciao!
Do
Thanks everybody, but I do not require royalties from NON John Curl supervised designs.
One reason that I do NOT give Blowtorch schematics here on this DIY website is because I do NOT want to be responsible for 'accidents'. You know, the implied warranty due to the fact that I published the schematic and somebody can't make it work.
The Blowtorch circuitry is marginally more sophisticated than the JC-80, mostly because it does not use global loop feedback to do the job. However, you MUST use V(high current select) Toshiba Jfets, in fact high V is all I ever used, to get it optimally right. Everything else is a compromise in some way.
Recently, I reverted to the JC-80 topology, a somewhat more complicated, and sophisticated approach, for my latest phono stage from Constellation Audio that we will be showing tomorrow at Las Vegas at the Venician (sp?) Towers. It was essentially as good as the Blowtorch approach, infinitely better measuring, and easier to build by 3'rd parties.
One reason that I do NOT give Blowtorch schematics here on this DIY website is because I do NOT want to be responsible for 'accidents'. You know, the implied warranty due to the fact that I published the schematic and somebody can't make it work.
The Blowtorch circuitry is marginally more sophisticated than the JC-80, mostly because it does not use global loop feedback to do the job. However, you MUST use V(high current select) Toshiba Jfets, in fact high V is all I ever used, to get it optimally right. Everything else is a compromise in some way.
Recently, I reverted to the JC-80 topology, a somewhat more complicated, and sophisticated approach, for my latest phono stage from Constellation Audio that we will be showing tomorrow at Las Vegas at the Venician (sp?) Towers. It was essentially as good as the Blowtorch approach, infinitely better measuring, and easier to build by 3'rd parties.
Hey John,
If ever you find some time, I'm sure most of us wouldn't mind buying the boards from you even if you had a disclaimer saying that you are selling as is without any explicit warranty and that we're totally responsible for making it work... 😀
Thanks for your great support, you're really a sport for supporting us even if we all know nobody is twisting your arm to do it.
Thanks
Do
If ever you find some time, I'm sure most of us wouldn't mind buying the boards from you even if you had a disclaimer saying that you are selling as is without any explicit warranty and that we're totally responsible for making it work... 😀
Thanks for your great support, you're really a sport for supporting us even if we all know nobody is twisting your arm to do it.
Thanks
Do
No more 'lifetime' guarantees'!
However, my board supply is limited, and they cost ME over $50ea, in quantity of 100, over 10 years ago.
However, if anyone of you is in the SF Bay Area, you might want to work with me on projects and then we can work something out.
However, my board supply is limited, and they cost ME over $50ea, in quantity of 100, over 10 years ago.
However, if anyone of you is in the SF Bay Area, you might want to work with me on projects and then we can work something out.
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