#1
Hey UG!


I'm rather new on bass still and am beginning to play more and more on the Marshall JCM 800 bass series amp we've got here at home, but there are a few of the knobs I don't really know and can't seem to figure out what do. They are:


"Slope" and "Mid Sweep [ranging from 400Hz-1kHz]".


Mid sweep, I can imagine, has something to do with the "Middle" knob right next to it. Perhaps it be the range of frequencies, the middle knob ranges over?

And as for slope, I really don't have any idea... Only thing I figured out is, that there's more output when it's at 5 than when it's at 0 or 10, other than that I don't really know.


Thanks in advance!
#2
free bump

don't know. what I've learned so far is that they are kinda rare and now I want one

i don't have the actual answers unfortunately. My guess is that the Mid Sweep just give you further control of the 'Mid' middle frequencies (seems cool). Slope is probably sort of like presence or resonance that we have on some guitar amps, probably more like resonance based on where it sits in the curve there. But like I said, I really don't know I'm just giving you a free bump.

I will now summon the ol' mighty Cathbard. He is currently sleeping in his den, but I will give the messenger boy your conundrum and see if the ol' mighty Cathbard can comeith.

until then...

http://www.drtube.com/marshall.htm#JCM800-1992
http://www.marshallforum.com/marshall-amps/4556-jcm800-bass-series.html
http://www.youtube.com/watch?v=XUwo4kU_WHU
Last edited by 311ZOSOVHJH at Oct 17, 2011,
#3
Mid sweep is what frequency it is affected around. Slope is how sharp the filter cuts off. A low slope means the filter is operating over a wider range of frequencies.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#5
Slope is the same as Q. A high Q means the curve is narrower and taller. Low Q means the curve is flatter.


Fo is Mid Sweep
delta f is Slope (effectively)
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
Last edited by Cathbard at Oct 17, 2011,
#6
Quote by Mausmaus
Hey UG!


I'm rather new on bass still and am beginning to play more and more on the Marshall JCM 800 bass series amp we've got here at home, but there are a few of the knobs I don't really know and can't seem to figure out what do. They are:


"Slope" and "Mid Sweep [ranging from 400Hz-1kHz]".


Mid sweep, I can imagine, has something to do with the "Middle" knob right next to it. Perhaps it be the range of frequencies, the middle knob ranges over?

And as for slope, I really don't have any idea... Only thing I figured out is, that there's more output when it's at 5 than when it's at 0 or 10, other than that I don't really know.


Thanks in advance!



the slope is like another frequency adjustment. its called a q.

it can affect a narrow bandwidth, or a larger bandwidth.
i may be wrong, but i believe the slope acts as a form of "cut-off" or "gate". it affects how the mid sweep reacts. they are both intuitive to each other.


again, i may be wrong, so cathbard may need to chime in


edit: nvm. he chimed in.
#8
Quote by Cathbard
Slope is the same as Q. A high Q means the curve is narrower and taller. Low Q means the curve is flatter.


Fo is Mid Sweep
delta f is Slope (effectively)



Aha, thanks! Was a bit confused at first but I think I understood it now.

It makes perfect sense then, that there's more output when Slope is in the middle than when it's max or min then - since the curve's top is at the middle of slope?

What do Slopes of less and more than 5 then do, boost the low and high frequencies respectively?


Thank you for the answers and sorry for my ignoracy and inability to just hear this out myself - my ears aren't that trained concerning bass lows, mids and highs etc., yet!