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sweepable midrange control?

Discussion in 'Pickups & Electronics [BG]' started by ugo, Aug 6, 2005.


  1. ugo

    ugo

    Jan 8, 2005
    Northern VA
    Sound Design Coordinator, Camel Audio | Designer, Ugo Audio
    i was reading at the bartolini site that the NS2TMB-18 preamp can have a switch wired in that allows the user to select the midrange frequency between 250, 500 and 800hz.
    http://www.bartolini.net/instructions/electronics/ntmb/ns2tmb18.htm (html)
    http://www.bartolini.net/instructions/electronics/ntmb/Ns2tmb18_Db18.1.pdf (pdf)

    my modulus has an NSTMB-18 in it, which i am assuming is probably an older version of the NS2TMB-18. i like the idea of being able to select the mid frequencies but i dont want to drill a hole in my bass for the switch. i'd also prefer a sweepable range rather than a switch with fixed frequencies.

    so i was wondering if perhaps this arrangement could be modified so that i can replace one of the normal pots with another stacked pot, and wire one of those to the mid control.

    electronics is not a strong point for me. i can follow instructions, but im not always the greatest at figuring out alternate wiring schemes. so i was wondering if someone here might be able to let me know if this is possible and what i would need to do in order to have a sweepable mid on my bass.

    i'd ask bartolini but previous experiances with their tech support have been kind of inconveniant. (no email, no phone, fax only, they'll call you...but wont tell you when, and if you miss the call, they wont leave a call back number.) while i can usually get access to a fax on the weekdays, it is not a favorite method of communication for me. so, if need be, i'll see fax them...but if someone here knows how to do this, it would be preferable.

    so, has anyone here ever done this? what parts (caps, etc.) would i need and how should it be wired?

    thanks,
    -ugo
     
  2. im just going to jump in and listen on this one, i love the sweepable mid option too, my BTB got me hooked and i want to get one for my next bass
     
  3. Zebra

    Zebra

    Jun 26, 2005
    Me too. I played around on a Cirrus and twisted the mid selector while a note was ringing and it was like a wah built right in. Not really, but it's a convenient control.
     
  4. ugo

    ugo

    Jan 8, 2005
    Northern VA
    Sound Design Coordinator, Camel Audio | Designer, Ugo Audio
    actually, thats kind of what gave me the idea for this. i used to have a BTB too and, when i saw the frequency switch option, it got me thinking back to that control on the BTB.

    whatever the mid control is set to now sounds pretty good for when i want a little boost or cut (though its kinda extra beefy), but i thought perhaps a bit more flexibility could be cool. however, i currently have no idea if how easy it will be to dial this tone back in again once i install a frequency sweep. so i should probably also consider the old saying of: 'if it aint broke, dont fix it.'

    i turned the mid control while watching a spectrum analyzer but it looks like 150-250 or 300 hz were all getting pretty evenly boosted. so im not really sure what this mid is actually set to, but i think it would stand to reason that its probably around the 200-250 mark since that would be the aproximate middle point for that range.

    on the cirrus, or at least on my cirrus, the mid control is only a boost/cut at a fixed frequency. (it is a really musical mid control though.) with the addition of a frequency sweep for the mid range...when you boost the mid, then turn the frequency knob while playing...you really do get wah-esque sweeps.

    by the way, i just checked my cirrus on the spectrum analyzer too. it looks like thats doing its work mainly within the 250-450 range, so mabey its set somewhere around 300+? whatever the case, its definitely working in a higher frequency range than the modulus' mid control.

    -ugo
     
  5. David Wilson

    David Wilson Administrator Staff Member Administrator Supporting Member

    Oct 14, 2002
    Lower Westchester, NY
  6. billbern

    billbern

    Sep 11, 2004
    Daytona Beach, Fl
    Endorsing: Inearz In-ear Monitors
    I know just enough about guitar electronics to really get myself into trouble, but that being said, isn't a sweepable midrange control a variable resistor used as a rheostat?
    I'd also love to have the sweepable midrange as on my BTB, on my NTMB equiped 55-01.
    Anyone from Bart or Lakland around?
     
  7. ugo

    ugo

    Jan 8, 2005
    Northern VA
    Sound Design Coordinator, Camel Audio | Designer, Ugo Audio
    thanks for the replies.
    if a sweepable mid turns out not to be in the cards, then yeah, i may end up having to come up with some switching. however, unless someone makes a stacked control that had both rotary and a normal pot in the same unit, i dont think i can add one of those either.

    so i'd probably have to go for a couple of push pull pots to get the extra mid frequency switching without having to drill a hole in the bass. that would be easy enough to do. not quite as flexible, but it would extend the range and it might even make it easier to dial in, in the long run. i may have to consider that.

    -ugo
     
  8. it is my understanding that the Aguilar OBP-3 preamp has a switchable midfrequency 400, 800Hz...however, I've heard it said (read it, actually) that if you change the switch for a pot you can sweep it.

    Nino Valenti would be a good source of info on this subject.
     
  9. David Wilson

    David Wilson Administrator Staff Member Administrator Supporting Member

    Oct 14, 2002
    Lower Westchester, NY
    You can wire it so that it's sweepable between 400hz and 800hz. Unfortunately, it can be a pain to implement. The mid freq sweep needs it's own dual ganged pot, so you can't have one stacked mid freq/cut&boost knob
     
  10. Zebra

    Zebra

    Jun 26, 2005
    I know some Cirri have the sweepable mid control. It's an option on the website, too, but not all have it. I believe it's only the active ones.
     
  11. ugo

    ugo

    Jan 8, 2005
    Northern VA
    Sound Design Coordinator, Camel Audio | Designer, Ugo Audio
    ah, ok...i didnt know they offered that as an option. mine is an active cirrus, but its an older one.

    i could probably work out a way to configure the controls so that i could use that, but i see your point about it being a bit of a pain to implement.

    -ugo
     
  12. that sucks :( , no way about it at all ?
     
  13. You just need a 3 way ganged pot with the correct values and tapers.....

    Custom pots

    I haven't done it, but was looking into doing it. Don't remember how big these are, but it would have been a tight fit for my bass. Looked like you could get 2 sections ganged independent of a third section, maybe even add center detent for the boost/cut, although the extra section would make it deeper, maybe too deep to fit. Depends on how thick your bass control cavity is.

    The other option obviously is add another pot, go from vol, bal, bass, treb, mid to vol bal bass treb, mid, mid freq.
    Not so easy to retrofit on existing bass....

    Randy
     
  14. David Wilson

    David Wilson Administrator Staff Member Administrator Supporting Member

    Oct 14, 2002
    Lower Westchester, NY
    no, sorry
     
  15. :(
     
  16. Actually there may be a way around it. I saw this in another post somewhere.
     
  17. David Wilson

    David Wilson Administrator Staff Member Administrator Supporting Member

    Oct 14, 2002
    Lower Westchester, NY
    IF you can get a custom made 3 ganged pot, with a dual ganged portion plus a separate regular portion, then it is possible.

    There are no off the shelf pots I have ever seen to do that.
    The link shown is for a custom pot mfr, minimum order for these is usually 1000.

    If you get past all that, you then run into the cavity space issues described.
     
  18. Passinwind

    Passinwind I Know Nothing Supporting Member

    Those custom pots are really hard to get in single unit quantities, in my experience at least. You typically have to order 100-1000, for the values I wanted anyway. I talked to State about this sometime last year, maybe things have changed? Those are nice pots in any case, albeit pretty expensive.

    There is another potential solution though, one that Craig Anderton mentioned in one of his books. You can gang photoresistor optoisoltaors and control them from one pot section, so a dual pot could then do boost/cut plus frequency sweep. The matching may or may not be good enough, depending on how picky you are. That's true of ganged pots as well though. The extra circuit board you'd need might create space problems as well too though.