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O'Conner "Power Scaling"


 
3/11/2004 1:52 AM
Jason
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O'Conner "Power Scaling"
Hello,  
I am building a JCM900 amp head. I would like to incorporate some sort of power scaling into the amp for home use also. The thing is, I hear the Kevin O'Conner power scaling sounds good in use. However, I also heard his books were really excellent and was greatly dissapointed. I haven't read anything in them I didn't already find on the net.  
Soo..I am wondering:  
 
1. Is the kit worth $120? Thats already about the cost I've spent for all the parts already, so it would double my building cost.  
 
2. Is this something I'm not able to find anywhere else?  
 
3. Is enough information given to be able to apply this to any amp without having to repurchase the kit again?  
 
The last one is really important.  
 
Thanks everyone.
 
3/11/2004 4:54 PM
Geoff Gross
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Doesn't he explain how he does it in one of the 'tut' books? (I only have vol 1) If so, that'd only run you $40 + whatever the parts cost is.  
 
Geoff
 
3/11/2004 5:06 PM
Jason
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I actually emailed Kevin O'Connor a while back about this. He just told me to buy the kit and some other condescending things. Power scaling is not explained in any available books. Vol. 4 is supposed to available in "~ Available early 2004 ~" and will cost $100 !!!
 
3/11/2004 5:43 PM
jaysg
email

quote:
"I haven't read anything in them I didn't already find on the net.[/QUOTE]Which book(s)? TUT is dense with ideas, circuits, minor boo-boo's ;), etc.[QUOTE]Power scaling is not explained in any available books. Vol. 4 is supposed to available in "~ Available early 2004 ~" and will cost $100 !!!"
Power scaling is outlined piece-wise in TUT v2, but not named. I initially balked at the $100 price he announced ~2 years ago. However, I wish he'd get it out. A lot of techs are going to make a lot of these mods once that book is available. Once he lets it go, it's gone and he knows it. It will probably cut his own amp sales measurably. I have one or two amps it's going into.
 
3/11/2004 5:44 PM
Ben
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He tends to be curt and condescending if you don't just want to buy parts from him at an inflated rate. He was rude to me so I will never buy any of his books or kits. I didn't get into this to make anybody profit. I do it for fun and education(of myself).  
 
FWIW  
 
There is a patent that describes this circuit in its basic form. I do not have the # on me but I have it at home. I'll try to look it up and post it.  
 
Ben
 
3/11/2004 10:30 PM
Ben
email

OK here's the patent number  
 
4286492  
 
 
There are a couple patent look up web sites but I like the US patent office site.  
 
Control for electronic amplifiers  
 
"""Abstract  
A circuit which allows for the simultaneous control of the bias voltages applied to the screen grids and control grids of output tubes while maintaining the ratio of said voltages, thereby providing a method for selectively varying a single plate characteristic (Power Output) of a tetrode/pentode vacuum tube. In the case of musical instrument amplifiers, it is a desirable effect to drive the power amplifier (output stage) beyond the point that said power amplifier is able to reproduce its input signal accurately, hence causing output distortion. Said point is known as the "Clipping Point". A clipping point is most usually achieved at high sound pressure levels which are uncomfortable and difficult to work under. By varying said voltages in the previously stated manner, one varies the clipping point accordingly, and therefore is able to obtain output distortion at variable sound pressure levels. """  
 
SOund like what you were looking for???  
 
 
Ben
 
3/12/2004 6:27 PM
jaysg
email
Patent # 4286492
Patent # 4286492 was issued to Claret; Guy P., September 1, 1981. It a) did not lower B+ one iota, so it's not that useful b) pre-dated the development of really good high power/high voltage mosfets(Hexfets) by a bunch of years c) has expired
 
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