[sdiy] to banana or not to banana

[Stewart Pye]

Hi,

I've been considering building a "banana" modular too. The thing that 
concerned me is interference from RF and 240V mains supply due to using 
unshielded cables. Can this be an issue?

Regards,
Stewart.




Cynthia Webster wrote:
> Hi Derek!
>
> Many of your concerns are simply not an issue, for example, Summing is 
> exactly the same as with any other jack;
> The circuit behind the front panel has no idea what type of jack the 
> wire feeding it is soldered to.
>
> Once the ground is stripped (cut) from an external input  you simply 
> re-ground the signal on the way out.
> Even an "all banana" system has a few typical audio output jacks for 
> the final output to your board or amplifier.
>
> More info on banana system grounding can be found here:
>
> http://www.cyndustries.com/modules_powerdist-FAQ.cfm
>
> It's a simple connection required if you want to patch between 
> different synths and once made - no other grounding
> is necessary on all of the cables, (remember that synth signal levels 
> are strong and far less susceptible to noise.
> (some phd in electronics may argue this tooth and nail until blue, 
> but) it just ain't necessary to use shielded cables with bananas).
> It is true that bananas are not a switching type jack, however a 
> simple workaround is to substitute a switching potentiometer or 
> "pull-pot" if you need to add another switch, (and frankly this gives 
> more options than a switching
> jack, (unless you were to add yet another front panel switch to tell 
> the switching jack, "not to switch this particular time").  There is 
> actually a switching circuit for bananas possible, but I'd rather not 
> dedicate any pc board space to
> the circuity required.
>
> How might one "loose the possibility of individual input attenuation" 
> ?  Unless you are specifically talking about
> making little quarter-inch phone plug attenuator assemblies, which are 
> rarely practical and often either broken or lost.
>
> The early Buchlas utilized several power supplies of different 
> voltages, there were no LEDs at the time so
> incandescent lamps were used all over the front panels and these had 
> their own power requirements.  Also the
> control voltage were a mighty ten or even more volts in the system, 
> while the outside world was using the standard
> one volt peak to peak audio line level and Don adapted his audio chain 
> to those levels. The simplest way to keep
> all of that isolated was to use separate connectors.  It was probably 
> this necessary isolation between control and
> audio that lead to exploration with opto-isolators and the rest is Low 
> Pass Gate history.
>
> While Don Buchla was working with Morton Subotnick and Cal Arts, Serge 
> Tcherepnin arrived on the scene
> and made three changes/improvements to what Don had started firstly by 
> making sub circuits into modules so
> that a user might manipulate the cores of certain circuits to their 
> own uses, rather than accepting whatever fixed function the front 
> panel proclaimed.  Secondly, Serge wanted to lower the entry level 
> price of getting a synth in
> the first place and he did this by standardizing the panels by 
> drilling the same size hole everywhere, and using
> xeroxed paper for the front panel legends so they could be re-arranged 
> to each customer's liking.  Serge also
> eliminated the mini-phone jacks and went with banana jacks only for 
> the sake of the size of the holes in his panels,
> the savings of ordering one part in greater quantity, standardization 
> of the same voltage levels for audio and CV, and here it is...  for 
> the sake of complexity.
>
> Instead of wasting front panel space with a few pitiful mults, the use 
> of stacking banana jacks allowed the most  flexibility as the multiple 
> jacks were no longer necessary, allowing you to mult anything to 
> anything anytime and
> give your patch cords the versatility of a queen on a chessboard - 
> being able to go in any direction - any way that
> you like with impunity!  That is mightily empowered patching indeed, 
> and your sounds created can or will reflect this difference.
>
> I've read of supposed limitations of things that you should or 
> shouldn't do with bananas as they might tax the power supply, but this 
> is apparently due to the use of cheap or marginally rated power 
> supplies as I completely ignore this
> and never ever have problems, (of course my own brand of power 
> supplies are quite beefy, intentionally), just use
> a decent power supply and not a cheapie.
>
> STS Systems has carried the Serge torch on to new heights for years 
> using banana jacks.
> Bruce Duncan at Modcan was inspired by Serge and others and chose to 
> build his system with bananas
> I liked what Bruce had done, that I started making banana modules 
> too.  There were other systems in Europe that
> also used bananas.  Once you start using them you really get addicted, 
> and frankly it's a bit of a drag when you find
> yourself back in front of an audio-jack-only system because you're 
> stymied and unable to do so many of the favorite  patching tricks that 
> you've learned because the damn jacks just won't let you, and there 
> aren't enough mults, and
> you must simplify everything and give up all the wonderful feedback 
> loops that you like to do and well, it all  just gets more vanilla, or 
> more "east coast", or just not what the patch might have been if it 
> had had a lovely panel full of banana jacks in the first place.  I 
> think Mr. Therepnin got it right.
>
> Go Banana!
>
>
> Cynthia
>
> http://www.cyndustries.com/
>
>
>
>
> Derek Holzer wrote:
>> My latest monstular synth is underway, with a nod towards the Buchla 
>> and Serge classics. Which has led me to the question of whether or 
>> not to banana it.
>>
>> So I wanted to ask people's opinions, pro vs con.
>>
>> I like the stackability of banana inputs, but you lose the 
>> possibility of individual input attenuation.
>>
>> Also, how do people handle the signal summing with bananas?
>>
>> Does that mean an extra buffer on the output side of the modules in 
>> the system rather than a summing buffer on the input side?
>>
>> And, do people still keep grounded, ac-coupled inputs on the same 
>> modules for external audio signals? Or could an incoming audio signal 
>> get "stripped" of it's ground via some converter panel, and run via 
>> banana to the module? I see that the old and new Buchla stuff in 
>> particular still uses grounded minijacks for some stuff like audio 
>> inputs.
>>
>> What are people's compelling reasons to go banana over balanced 
>> minijack?
>>
>> In the end, will I have panels with both anyways?
>>
>> Best!
>> Derek
>>
>
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