Need more mids on my twin &nb

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Searing
Junior tube assistant
Posts: 71
(2/25/04 3:51 pm)
 Need more mids on my twin
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 I have a 65 reissue twin with Doug's AB763 board in it. I would like to get more mids, is there any way to do this?
Thanks
Chris
 
bluesbear
Hey get your own solder
Posts: 341
(2/25/04 5:55 pm)
 Re: Need more mids on my twin
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 Decide which channel you want to do. Change the slope resistor to 56K and the midrange pot to 25K. Change both tone caps to .022mF. That ought to do the trick. I always change those parts in any Fender I own. It really gives the amp balls.
Dave
 
Searing
Junior tube assistant
Posts: 72
(2/26/04 11:38 am)
 Re: Need more mids on my twin
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 Dave,
Thank you for the tip! Okay, is the slope resistor the 100k that is behind the two caps on Dougs AB763 board kit layout diagram? Also, are the tone caps the two that are connected to the mid pot itself? I am not sure what is what here?
Chris
 
Searing
Junior tube assistant
Posts: 73
(2/26/04 11:53 am)
 Re: Need more mids on my twin
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 Dave
Does the pot need to be linear or audio because I cant find an audio 25k but I can find a linear 25k pot? Thanks
Chris
 
ganzonimx
Hey get your own solder
Posts: 406
(2/26/04 12:05 pm)
 Re: Need more mids on my twin
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 Yes these are the parts. The slope resistor is the one that connects the 250p and the 0.047 cap, the tone caps are the 0.1 and 0.047 cap next to the 250p cap.

You could also try first just changing the mid pot to 25k. To get a idea how that sound you could leave the 10K pot and replace the wire that connects the mid pot with the ground bus with a 10 to 15K resistor. That gives you already a nice mid boost and slight volume boost. If you like it, change the pot to a 25K pot.

I never tried to change the slope resistor and the caps, but I'll try that as soon as I got my Twin on the bench.

Cris
 
Searing
Junior tube assistant
Posts: 74
(2/26/04 1:09 pm)
 Re: Need more mids on my twin
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 Can I use a linear pot instead of an audio pot for this?
Chris
 
ganzonimx
Hey get your own solder
Posts: 409
(2/26/04 1:15 pm)
 Re: Need more mids on my twin
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 generally the mid pot is linear.

Cris
 
Funkalicousgroove
Junior tube assistant
Posts: 1
(2/27/04 4:37 pm)
  Mid boost
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 Mids are subjective, If you're looking to increase your upper mids you can simply change your treble cap to 500pf or so, I use a B100k for my mid pots which takes the "scoop" completely out of the midrange. If you go to www.duncanamps.com you can download the tonestack calculator, at that point you can plug in different values for your pots, slope resistor, and tone caps. Changing your tone caps to .022uf WILL NOT boost your mid response, It will however decrease your bass response and give your amp a more hollow marshally response (Kind of defeats the purpose of owning a blackface fender if you ask me) Although it makes for a very cool tone on it's own.
 
Searing
Junior tube assistant
Posts: 75
(3/2/04 11:53 am)
  Re: Mid boost
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 Okay, one thing though, the schematics and the layout diagrams for a twin call for an audio taper pot for the mid not a linear. If I put the linear pot in will it work or would an audio pot be the way to go? Thanks!
Chris
 
Funkalicousgroove
Junior tube assistant
Posts: 7
(3/2/04 4:54 pm)
  Re: Mid boost
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 An audio taper pot woks on a logarythmic scale, i.e, the taper is scaled so that it "Sounds" better or more even from top to bottom. A Linear taper is just that, to human ears it will sound like very little change until about the last 1/3 of the rotation, and then you'll hear most of it. The important thing is that it is your amp, and you should use what sounds best. I suggest trying the linear taper drawing from personal experience, but if it's not gradual enough swap it out for the audio. Did you download that tonestack calculator? it's free and should answer all of your questions about how components will effect the frequency response.
 
Searing
Junior tube assistant
Posts: 76
(3/2/04 6:25 pm)
  Re: Mid boost
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 Funkaliciousgroove,
I tried but only found the tube info download. I will go there now and look around again. Thank you very much for your help!
Chris
 
Searing
Junior tube assistant
Posts: 77
(3/2/04 6:42 pm)
  Re: Mid boost
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 I got the tone stack calc. This thing is cool! I think I will start with just changing the mid pot to a 25kL for now. Again, thanks Funkaliciousgroove.
Chris
 
Funkalicousgroove
Junior tube assistant
Posts: 8
(3/4/04 11:17 am)
  Mid boost
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 Here is a cool trick: if you don't use your bright switch you can re-wire it for a mid-boost. Change your treble cap to a 1000pf orange drop and then wire the lead that would normally go to the treble pot to one of the lugs of the bright switch. wire a 500pf ceramic or silver mica between between both lugs and then connect the treble pot to the opposite terminal of the switch. when the switch is open you'll have roughly 330pf for your treble cap, in the closed position you'll have 1000pf providing a very musical and very useable mid boost
 
geoffreyreed
I will work on all amps
Posts: 323
(3/9/04 3:06 pm)
  Re: Mid boost
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 Searing,
with all due respect, I believe Funka, in some respects is incorrect, and Bluesbear and Ganzo are correct,...especially as I just did this mod or very nearly the exact mod, last week, incidently came up with almost the same values on my own. Funks mod will give you more mids but they will be on the treble control. The .02s suggested by Bluesbear will bring up the mid , and bass turn over points and the 56 k brings in more mids to temper the over bright "scooped" mid AB763 circuit. The twenty five K is great for the mid control not only giving you more mid in the center position, ( the original 100K and .047 cap control the amount of mid coming through. The mid control itself shunts the main signal to ground so the higher value this pot is the more mid there will be. If you replace the treb disc cap with a silver mica the high end will be less suseptible to feedback, the ceramic discs can be a little microphonic. Also linear pots are fine for tone controls unless you find log taper tone controls that are log either side of center. Tone controls are almost always linear as far as I know. Geoff  
 
Funkalicousgroove
Junior tube assistant
Posts: 16
(3/9/04 5:58 pm)
  Upper mids
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 What I was trying to illustrate is that there is no wrong answer, as long as you know what you're looking for. I wanted to Give options, and tricks I know instead of a Blanket cure all answer. Yes changing the tone stack to more of a tweed style works, that's only one option. I say use what works for your ears. I also Gave a link to a great tone stack calculator, which I reccommend everyone download. It shows in Black and White exactly what changing your component values do. My mods Add Upper Mids, I believe they help the guitar cut through the mix and keep your tone from getting muddy, But Like I said, Use your ears-It's YOUR amp
 
bluesbear
Hey get your own solder
Posts: 346
(3/10/04 12:38 am)
  Re: Upper mids
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 "What I was trying to illustrate is that there is no wrong answer, as long as you know what you're looking for. "

I'm with you! My way works for me, but maybe not for everyone. It's just one more option, one that works. I have an amp that I use for trying out ideas. A couple weeks ago, I gutted it and rebuilt it 3 times just to try things out. I didn't like anything I tried so I ended up exactly where I started.... except for the experience. I learn that way.
Dave
 
Searing
Junior tube assistant
Posts: 78
(3/15/04 11:17 am)
  Re: Upper mids
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 Thanks to all for enlightening me on this subject! I will try all of the options you guys gave.
Chris
 
 
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