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John Curl's Blowtorch preamplifier part II
John Curl's Blowtorch preamplifier part II
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Old 27th April 2013, 09:56 AM   #38631
jacco vermeulen is offline jacco vermeulen  Netherlands
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Quote:
Originally Posted by iaxxaxxai View Post
Forget about it
If you and a million others were willing to pay $25 for a JFET pair every time, it wouldn't be an issue.
You skipped the most vital criterium, the fact that vacuum valves still is a multi billion dollar business.

(two decades ago, the situation was reversed : folks got out of tube amps and into SS, as it became harder to find valves and/or decent OPT's)
 
Old 27th April 2013, 10:09 AM   #38632
EUVL is offline EUVL  Europe
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You can still use BF862, 2SK3557, 2SK209, 2SK2145, ......

I do not see any problems.
You just need to start building circlotrons, or Linsley-Hood-type quasi-push-pull's.


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Old 27th April 2013, 10:12 AM   #38633
EUVL is offline EUVL  Europe
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And progress is iphone, 256GB USB sticks the size of a finger nail, ..... not analog electronics.
Why? Analog does not sell in 3-digit millions a quarter at 3-digit USDs.

Sad, but true.


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Old 27th April 2013, 10:32 AM   #38634
godfrey is offline godfrey  South Africa
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And yet 741 opamps and 2N3055s just won't go away. I guess they're good for industrial stuff.
 
Old 27th April 2013, 10:36 AM   #38635
SY is offline SY  United States
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John Curl's Blowtorch preamplifier part II
Quote:
Originally Posted by jacco vermeulen View Post
If you and a million others were willing to pay $25 for a JFET pair every time, it wouldn't be an issue.
I would IF they were as close to nominal spec as a pair of tubes are. The problem is the three or four to one spread in gm and idss, meaning that I have to buy twenty FETs to get two I can use optimally (if I'm lucky and they're not all clustered over to the wrong side of the spec limits). In many circuits, you can design around this, but not in all- and unfortunately, not in the circuits where I like to use FETs.
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Old 27th April 2013, 11:27 AM   #38636
jacco vermeulen is offline jacco vermeulen  Netherlands
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Likely the reason I run a semi museum.

(afaih, there are still folks ready & willing to pay dearly for mil-spec matched 6SN7 pairs)
 
Old 27th April 2013, 11:29 AM   #38637
dadod is offline dadod  Croatia
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Quote:
Originally Posted by Steve Eddy View Post
Funny isn't it how tube circuits can sound absolutely fantastic, yet there are no complimentary devices in the tube world.

se
Sorry, but as not native Englesh speaker I would like to know if "complimentary" has same meaning as complemetary in American English?
 
Old 27th April 2013, 11:35 AM   #38638
SY is offline SY  United States
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John Curl's Blowtorch preamplifier part II
No, it's a common writing error. "Complementary" is the right word unless the devices are telling you that you're a handsome and intelligent fellow.
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Old 27th April 2013, 11:49 AM   #38639
jacco vermeulen is offline jacco vermeulen  Netherlands
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Buy a valve, get a transistor for free. (complimentary towel of the tube hospitality world)

Speaking of semi's and tubes : hybrid folded cascode (bad boy JC Morrison)

Last edited by jacco vermeulen; 27th April 2013 at 11:52 AM.
 
Old 27th April 2013, 12:28 PM   #38640
EUVL is offline EUVL  Europe
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> The problem is the three or four to one spread in gm and idss, meaning that I have to buy twenty FETs to get two I can use optimally

I am sure Jacco can help you out.

But serious, you can still get matched pairs with specific Idss at reasonable price (less than tubes).
And tubes also need matching, not true ?


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