Bassballs schematic search

[Nikolay]

Hi friend, I search Bassballs schematic. Can anyone help me ?
Thanks

[cd]

http://files.bighosting.net/ab4177.pdf

[Mark Hammer]

A-HA!  So someone archived at least one of the postings from Ambrose Chapell's old "Clone Wars" site.  A hearty thanks to whomever it was.

IIRC, there may be an error in the PCB layout, but I leave that to others who have made it more recently to confirm or disconfirm.  Even if there is one (it was on ONE of his layouts, I know), I remember it as being trivial to correct.  The sort of thing that an X-acto blade snip here and a gracefully bent lead there could easily fix.  Again, I may be wrong about it having been THIS one, as opposed to his Blue Box layout, so don't get all antsy just yet.

Since we have the schem to talk about, and since some have inquired about it recently, note the following:

1) The Bass-Balls is essentiallya bigger, badder version of the Dr. Q.  You will note that the DQ uses a switch to reconfigure the filter into one of two topographies.  In this case, only one of the filter configurations is used, but that same bandpass filter type is duplicated using two "staggered" copies - one for lower freqs and one for mids and highs.

2) The trimpot on the DQ can be used to "tune" the filter sweep a bit.  It can be used in identical fashion here.  In fact, I recommend replacing the trimpots with chassis-mount pots so that the amount of stagger can be adjusted.  

3) Note that the tuning trimpots/pots not only set where the sweep for each filter section begins but also how far it can sweep, to some extent.  This means that some interesting qualitative feels can be achieved by playing with the tuning trimpots/pots.

4) The two filter sections are passively mixed via 2k7 resistors.  They do not HAVE to be eiher mixed in equal proportion or even combined.  You could set up another jack with its own 1uf cap and 47k terminating resistor and simply reroute the 2k7 resistor of one of the filter sections there, so that you have two outputs, one for each filter.  This will let you do some stereo tricks (e.g., fuzz/chorus one and leave the other as is) or let you use only one of the filter sections at a time for a more DQ-like sound.  For mixing in mono, I suppose the 2k7 resistors might be replaced with 1k resistors and a 10k linear pot for shifting emphasis.

5) Like the Doctor Q, I gather this one also relies on use of a 1458 dual op-amp for the envelope follower section (not for the filter sections themselves).  I suppose it *could* be modified to use another op-amp, like what Jack Orman did with the Doctor Quack, but then that particular design (both DQ's) essentially "slaved" the filter op-amp to whatever op-amp the envelope follower needed. In this case, it uses a pair of dual op-amps, so it is feasible to stick with the crappy one for envelope follower purposes and use a sonically "better" one for the filters.

6) Like so many other swept or sidechain-directed pedals, thisone also uses a simple half-wave rectifier, formed around the op-amp with the 220k feedback resistor and the diode on its output.  Like all such rectifiers/followers, overall sensitivity can be adjusted by altering the value of the feedback resistor (more resistance = more sensitivity/sweep) to cope with the dreaded "undersignalitis".  Note as well that the attack/rise time is set by the 100R resistor in conjunction with the 4.7uf cap to ground.  Increasing the resistance value will slow the rise/sweep, and increasing the cap value will slow the rise AND fall of the filter.  
One of the quirks of the Base-Balls is that the attack time is so quick as to seem like the filter ONLY falls.  In other words, while it *sounds* like it has reverse/downward sweep, that's only because the upward sweep is too fast to detect.  Neat.  If you slow down the attack time by means of series resistance or cap value, the rise starts to beome more detectable and it starts to go "wow", rather than "ow".  Because the series resistance reduces current and limits sweep, don't make any attack control more than about 1k in resistance (fixed+pot) overall.
The 330k resistor to ground sets the decay time; i.e., the time taken for the charge stored in the 4.7uf cap to bleed off to ground.  You can alter the decay time of the pedal by playing with the value of the cap to ground, OR the value of the resistor to ground.  Smaller caps bleed/decay faster.  Caps with smaller resistances to ground are discharged faster.
One of the things I've never tinkered with but which sounds intriguing is to run TWO diodes out of that op-amp and use slightly different itme constants for each filter section.  In such a case, I suspect that the 2N5088 that links the two filter sections to the same envelope follower could possibly be scrapped.  I'll bet having the upper filter fall back slower than the lower one would sound kinda neat.  To do that, simply connect two "copies" of the diode/cap/resistor networks you see after the op-amp (but before the trimpot), one to each trimpot.  For the filter section with the pair of .0047uf caps, use a 22uf cap instead of the stock 4.7uf cap.  Note that this will slightly retard the rise time as well.

Ready to keep going?

7) Trace the switch conections backwards and you'll see that the "Fuzz" function on the Baseballs uses the output of the overdriven envelope follower op-amp as its "fuzz" source.  While it accomplishes the goal, like most "something-for-nothing" features, it comes with some problems.  First, it is an appallingly bad distortion/fuzz.  Some may find it charming.  Personally I find it inadequate.  Moreover, the amount of "fuzz" you get depends on the setting of the sensitivity control adjusting input to that follower stage. This slaves/yokes fuzz amount to volume level to sweep amount.  If you want more sweep you WILL get more fuzz and more volume, with no way on board in the stock design to tame that volume level.
What I did on mine (and several others like Rick Lawrence have also done) is to replace the 100k/47k resistive attenuator network with something involving diodes to ground.  The resistors simply reduce the "fuzz" level proportionally.  Diodes set it at a fixed ceiling so that things can get fuzzier but not louder.  This way you can keep approximately unity gain between input and output jacks, no matter where you set the sensitivity control.  Alternatively, consider replacing the 100k/47k network with a 100k log pot, a 24k-27k input resistor on one leg of the pot, and a 24-27k resistor on the ground leg.  This will let you adjust the fuzz level independent of fuzz amount so you can egt unity gain, OR a volume boost if you feel like it.
Finally, note that there is no reason why you couldn't have a clean feed to one filter section and a fuzzy one to the other if you felt like it.  The two filters each go through 470k input resistors to a common .047uf input cap, but you could easily connect each filter to its own .047uf input cap, hook one up to the "clean" source" and the other up to the "fuzz" signal.


There.  Is that enough to keep all you sickos buys perfing and ordering parts for a little while? :lol:

This particular pedal has more than enough "points of entry" for mods to allow an almost infinite number of unique builds, and customize the pedal to your own needs and creative impulses.  That it uses, and only NEEDS to use, common garden variety components is just icing on the cake.

[new_winter]

I believe that I see in http://hammer.ampage.org

[blandoon]

(slightly off topic, but...)

I didn't know that thing was designed by David %^&*erell... he's something of a legend in the synth/effects industry. See http://www.akaipro.com/int/plugs/.

[Mark Hammer]

Yeah.  Dave has done lots of neat stuff, including, I think the Microsynth for E-H and plenty of analog synths in Britain as well.  Seems to me I heard he is still going strong and involved with E-H.

Ton seems to be busy at the moment, but perhaps either he (when a moment presents itself) or someone can confirm or deny this.

[puretube]

yep, Mark! (EMS ?) Small Stone?

That man got my greatest RESPECT!

(ok, along with a small handful of others...)

[Nikolay]

Thank you CD, thanks Mark
I try to make bassballs