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Re: Tightening up a loose sounding low end


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2/8/2004 4:42 PM
Chuck Re: Tightening up a loose sounding low end
Thanks again for straightening things out Bruce. I assumed that "B+ resistors" was enough info to know that I meant the B+ rail and not the plate resistors.  
I'm gonna have to slow down and try to be more clear before someone blows up thier stuff :(  
 
Chuck
 
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2/9/2004 5:35 PM
dazco

I went to 150 plates which may or may not be right. But i found some other tweaks that totally changed to entire amp's sound. It now sounds un-freaking-real ! No exaggeration. I can't even believe what i'm hearing. Low end is now very tight, but thats only a small part of the overall improvment that has the amp sounding litrerally infinatly better. I've never owned an amp that sounds this good, and i've owned a boatload. Thanks for your help, both of ya......
 
2/10/2004 1:42 AM
Chuck
Wow! What the heck did you do that made such a radical improvement?  
 
If by "150 plates" you mean plate load resistors, I would think that would make the amp fuzzier and less defined by itself. If you change the cathode resistors as well thats a different story.  
 
So tell us...What tricks helped create the worlds best 18 watter?  
 
Chuck
 
2/10/2004 6:51 AM
dazco

Well, yes i did change the cathode resistors among other things. I know that the way i have the tubes biased is not correct, and i intend to try and learn how to get it right for the cleanest tone. But it sounds so good i don't wanna mess it up by changing too many things. Gotta remember what i change. In any case, the things that seemed to make the biggest change were a 1 meg volume pot on the gain channel, a 680pf coupling cap from 1st to 2nd stage, and bypassing the cathode on the final stage where it goes into the tone stack with a .047. I'm sure thats not an electronically sound thing to do, but little of what i do seems to be. *LOL* Heck, i'm just learning this stuff.  
 
But in any case, it seems all of the things i did contributed because today i began removing them one at a time and testing the amp after each one to see where the improvements were. I didn't try everything, but i did swap back the original plate and cathode resistors and cathode bypass caps. I ended up butting the mods back because thats where it sounds the best. But when i clean up with the guitar volume it doesn't do that as well as i'd like, (not badly, but not as good as i want)so i'm pretty sure i need to bias the tubes correctly. Unfortunatly i'm not exactly sure how. I know now i have to adjust the cathode bypass resistor to do so, but i have no way of knowing when it's right. One guy told me it's right when it's at 1/2 of the B+ voltage, but Randall Aiken said what i THINK was 1/2 plus about 50 volts. I say "think" because i don't speak or understand his language !! *S* thats not a slam but a compliment to his vast knowledge. However, he could take a lesson from Wild Bill in how to explain things to an electronic moron like myself ! *LOL*
 

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