John Curl's Blowtorch preamplifier part II - Page 3148 - diyAudio
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Old 14th December 2012, 06:17 PM   #31471
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2SK389GR
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Old 14th December 2012, 06:36 PM   #31472
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Old 14th December 2012, 07:31 PM   #31473
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GR is best for the Siliconix mod.
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Old 14th December 2012, 07:31 PM   #31474
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Quote:
Originally Posted by gk7 View Post
Itīs the JC-2 (or ML-1, not JC-1 as I wrote before), and itīs not a wish list,
itīs what you can get with discrete. For IC opamps it seems you can never get
low noise, Fet input, high slew rate and a class A output stage in _one_ package.

John, thank you for the detailed explanation. I have mixed up JC-1 and JC-2. What I wanted
to say was "a JC-2 line stage built with modern (well modern, the P-channel part is already
out of production) Thoshiba Fets". Iīm not aware of a integrated solution that will match that.
The question was not about doing in ICs the same things (topology, biases, differential complementary stage, etc...) you can do with discretes, but to provide the same level of objective performance. When you evaluate a discrete solution vs. an IC solution you don't necessary know about topology (Class A) output stage bias current, etc... OTOH, knowing such details in advance and evaluating based on the "sound quality" only is equivalent to peeking in a blind test.

On the same note, you could argue there isn't any IC providing 200W in 4ohm load, so ICs must be inferior. As much as I can argue you can't build a 1000V/uS gain stage (or anything close to the THS4631, like 325MHz unity gain frequency and 80dB gain) with discretes on a regular PCB.

So, as I said, I see this going nowhere, therefore I'll stop here.
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Old 14th December 2012, 07:41 PM   #31475
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Waly you are interpreting things into my post I never said.
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Old 14th December 2012, 08:03 PM   #31476
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Quote:
Originally Posted by john curl View Post
The confusion is understandable. The JC-2 and the ML-1 were just different versions of the same preamplifier. Mark wanted to continue using the JC designation, and I threatened to sue him if he did, while not paying me my royalties. That is why the ML-1 came into being.
In hind sight , you should have let him, now he gets all the credit ......
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Old 14th December 2012, 08:04 PM   #31477
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Originally Posted by john curl View Post
Wayne and PMA, thanks for your inputs on the A21. I have one on my test bench right now, AND I am going to give it to my business partner, because it will NOT drive my WATT's properly, which are 4 ohms and below in drive Z. With 4 ohm and below, the limited number of output devices causes a small, but measurable amount of higher order distortion, which puts me off for MY set-up. My colleague is more relaxed, even though he also has a Vendetta equipped CTC Blowtorch that we made together.
What are you going to get now John, JC-1 's ...
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Old 14th December 2012, 09:32 PM   #31478
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I once built a 250W/channel power amp with a slew rate greater than 1000V/us. It CAN be done, if you care enough to do it.
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Old 14th December 2012, 11:51 PM   #31479
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Originally Posted by kgrlee View Post
That's a good reason.

What is a 3.6? What is a Big Bembeh? Yes please to your list.
I am assuming that the "3.6" refers to the Magneplanar 3.6 (a planar-magnetic/ribbon hybrid loudspeaker from Magnepan Incorporated (MG 3.7)), a loudspeaker that presents a fairly resistive, largely 4-ohm load.

Sorry, I have no idea what consitutes a "Big Bembeh"...

Good luck!
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Old 14th December 2012, 11:52 PM   #31480
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Originally Posted by scott wurcer View Post
Which basement in Hauppauge do these come from?
They've been around a while. More than 2 decades if I recall correctly.

Are the fet numbers of any interest? I know the rep, and could ask.

jn
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