passive mid cut

[dub]

Does anyone have a design for a passive mid cut control for bass?
I've seen the rothstein guitars one which looks OK but I would like to keep my standard hi cut tone control separate.

[Al Heeley]

I'm looking into an onboard simple passive mid cut via a mini switch mounted on the bass body, for my warmoth Gecko. It's Seymour Duncan Basslines active(but quite low output) pickups, other than that its wired standard jazz, one vol knob per pickup and a master tone. I want to be able to scoop the mids with a flick of the switch. Anyone looked into one of these Rothstein or Torres passive mid cut/boost circuits?
I'm assuming its a variable resistor, 2 pairs of caps and resistors plus a small inductor, but I'd need some steer on the schematic and the component values.

[lettsguitars]

Not sure about this. We had a request for a passive mid boost/cut button but had to go active in the end. The only way we thought it could work was if the pickup had seperate different shaped coils. Didn't work. The pups ended up too quiet and the tonal difference was inaudible. If anyone has an answer i'd love to know the secret.

[nugget]

[url="http://www.geocities.jp/dgb_studio/index_e.htm"]http://www.geocities.jp/dgb_studio/index_e.htm[/url]

Been looking into this a lot for a very interesting upcoming project..... Above link is the diagram and the same site has a cool LC calculator for working out values etc.

The gibson ripper bass has a 5 position mid cut and schematics are available on internet.

A lot has been written on passive mid cut and the concensus is it's not really viable/useful. The use of bandwidth filters cuts output significantly and there is a lot of interaction between std 'tone' cut and any mid cut imposed.

A GOOD transparent preamp should sound exactly the same with controls flat as in passive mode (not many preamps do!!) and therefore a GOOD active mid boost/cut wont loose any tone??

[lettsguitars]

[quote name='nugget' timestamp='1328547516' post='1528862']
[url="http://www.geocities.jp/dgb_studio/index_e.htm"]http://www.geocities...dio/index_e.htm[/url]

Been looking into this a lot for a very interesting upcoming project..... Above link is the diagram and the same site has a cool LC calculator for working out values etc.

The gibson ripper bass has a 5 position mid cut and schematics are available on internet.

A lot has been written on passive mid cut and the concensus is it's not really viable/useful. The use of bandwidth filters cuts output significantly and there is a lot of interaction between std 'tone' cut and any mid cut imposed.

A GOOD transparent preamp should sound exactly the same with controls flat as in passive mode (not many preamps do!!) and therefore a GOOD active mid boost/cut wont loose any tone??
[/quote]Active mids are gooood. Especially mid freq which is a lot of fun to twiddle.

[nugget]

[quote name='lettsguitars' timestamp='1328547673' post='1528868']
Active mids are gooood. Especially mid freq which is a lot of fun to twiddle.
[/quote]

Sorry to steal the thread - Mr Letts - Your mate at IMP (or is it you?) has some preamps (and tasty pups) shown but no details, specs and prices, any plans to update the website??

[lettsguitars]

[quote name='nugget' timestamp='1328548904' post='1528900']
Sorry to steal the thread - Mr Letts - Your mate at IMP (or is it you?) has some preamps (and tasty pups) shown but no details, specs and prices, any plans to update the website??
[/quote]Tell me about it. I keep tellin him but, what can you do? I'll mention it, again. Thanks.

[Davebassics]

I can in detail explain a active filtering system I adopted for my preamp designs.

In short, summing a inverted band passed signal with the input so the 'mid cut' frequencies cancel each other out. You also can adopt pots and extras to make it parametric.

I have no answers for passive designs unfortunately.

[Al Heeley]

wondering if anyone's fitted a bass with the torres system, the push-pull pot with an inductor and a few caps and resistors soldered to it - someone MUST have done so, but I'd assume the cap and res values would need tweaking.
http://www.guitar-mod.com/rg_passive.html

[deepbass5]

Slightly left field, but I installed the bass version on my passive schack and really loved the result; their new 3 pos switch must be another useful addition that may come close to what you are after worth checking if they can do the onboard version with the switch.

http://www.stellartone.com/Page.asp?NavID=273

[LawrenceH]

There is a varitone jazz plate available on ebay that incorporates a mid scoop, somewhere or other there is a youtube video (I think it's the same one as on ebay) where it sounds pretty usable. I guess these things work by using an RLC bandpass filter that bleeds the mids to earth, but calculating component values for your own, wouldn't that be dependent on impedance of the particular pickups used? That would make it more complicated

[Al Heeley]

$99 for a passive control is[b] outrageous![/b] Thx for the link but I need to find somewhere on the internet the circuitry for this. It should be no more then £10 for parts and 10 mins soldering.

[nugget]

[quote name='Al Heeley' timestamp='1328562264' post='1529235']
$99 for a passive control is[b] outrageous![/b] Thx for the link but I need to find somewhere on the internet the circuitry for this. It should be no more then £10 for parts and 10 mins soldering.
[/quote]

As above quoted above here's the link to the schemes
[url="http://www.geocities.jp/dgb_studio/index_e.htm"][color="#0f72da"]http://www.geocities...dio/index_e.htm[/color][/url]


Yes $99 is outrageous [u][b]unless[/b][/u] they have done extensive practical research into the component values rather than just going from the calcs.....

[nugget]

[quote name='Davebassics' timestamp='1328550710' post='1528952']
I can in detail explain a active filtering system I adopted for my preamp designs.

In short, summing a inverted band passed signal with the input so the 'mid cut' frequencies cancel each other out. You also can adopt pots and extras to make it parametric.

I have no answers for passive designs unfortunately.
[/quote]

I wanna know more - I'll send you a PM rather than clutter this post

[Al Heeley]

[quote name='nugget' timestamp='1328562736' post='1529249']
As above quoted above here's the link to the schemes
[url="http://www.geocities.jp/dgb_studio/index_e.htm"][color=#0f72da]http://www.geocities...dio/index_e.htm[/color][/url]


Yes $99 is outrageous [u][b]unless[/b][/u] they have done extensive practical research into the component values rather than just going from the calcs.....
[/quote]thanks nugget 4558 op amp circuit would make it an active control, the passive ones i was looking at earlier were just a pot, inductor, 2 caps, 2 resistors. Thats the Torres/Rothstein unit

Edited February 6, 2012 by Al Heeley

[Al Heeley]

Change of plan - decided to try out a cheap 3-band bass pre-amp to have a play around. one of the [s]cheap[/s] cost-effective Artec SE3P-A units with a mid cut/boost and freq sweep. This is 9V, i already have 9V powering the pups, is it better to use same battery to power both or put in a second separate battery for the pre-amp?

[Davebassics]

I've never used Active pickups but I would imagine it would depend on where in the chain the power is decoupled from the signal. If the circuit is decoupled at the tone pot then you should be able to get away with using a single battery. However I would imagine the signal coming into your active preamp will be biased back at 0V and will need a second supply for it to operate.

I'm sure someone will be able to give a much more certain answer but I think thats how it would work.

[MoonBassAlpha]

Kent Armstrong Tone Choke.
It's fitted as part of U.S. Masters Multi Voice Passive circuit option: [url="http://www.usmasters.com/basselectronicswht.htm"]http://www.usmasters.com/basselectronicswht.htm[/url]
It quite different and a bit subtle, but I noticed the difference a lot more when I added a tweeter box to my Barefaced Compact cab.
I quite like it.

[Al Heeley]

I have a circuit:

[Al Heeley]

found some more useful torres stuff here:
http://www.jpbourgeois.org/guitar/microsbis.htm#Midrange%20Modification

[Mog]

Wouldn't a fender TBX do something similar? May be worth looking into.

[BigRedX]

What's wrong with the tone controls on your amp?

[Al Heeley]

What? Move across the floor to get to my amp? Guitarist would steal my mic spot. Really.
TBH also farting around with a 10-band eq mid gig to get a scooped tone is a pain compared to turning a knob on the bass.

[nugget]

[quote name='Al Heeley' timestamp='1328709298' post='1531444']
found some more useful torres stuff here:
[url="http://www.jpbourgeois.org/guitar/microsbis.htm#Midrange%20Modification"]http://www.jpbourgeo...%20Modification[/url]
[/quote]


Thats good stuff !! Thanks for posting that

[Al Heeley]

My £36 parametric 3-band pre-amp came yesterday evening, duly fitted to the Gecko, will give it a good trial at tonights practice.
[url="http://www.artecsound.com/pickups/electronics/se3p.html"]http://www.artecsound.com/pickups/electronics/se3p.html[/url]