Small problems

rogic · March 21, 2003, 7:50pm

Hi,

I have problems with jittering; Connected 16 pots to MB64, and when I finish moving pots, I let MB alone and after some 10 secs, last CC changed start jittering. Not much at all, something like:

105

106

105

106

105

106

So it only jitters a little; Not a real problem with applications but it can be pain in the ass if you want to use ‘learn’ function of host application. In some cases this doesn’t occur at all, but I was not able to figure out the reason why. Dynamic jitter filter doesn’t fix this. Pots are on 25 cm cables to AIN, and connected ‘starlike’, like shown on Tor Arne’s site. Pots are 10K.

Is there any rule or something for grounding unused pot inputs of the AIN, or any other tip regarding this? Thanx.

d2k · March 21, 2003, 7:55pm

Is there any rule or something for grounding unused pot inputs of the AIN, or any other tip regarding this? Thanx.

Yes! From AIN PDF:

if you leave out a 4051, clamp the appr. analog input (J5:A0, … J5:A3) to ground!

Also, if ur only using 1 AIN module clamp unused pins of J6 on the core (what the AIN goes to) to ground as well…

Best…

Dan

rogic · March 21, 2003, 9:20pm

I’ve done all that… if I haven’t done it, my midiox monitor screen will be filled within a second.

jerash · March 22, 2003, 4:50am

Pots are on 25 cm cables to AIN, and connected ‘starlike’, like shown on Tor Arne’s site. Pots are 10K

hello,

I’m on the way to solder my 64 pots… and wondered about the StarLike cabling for 0-5V.

There’s only one connection on AINx4 modules (J7), so one wire would go to the first pot and then make a bride to the second, then to the third ???

If someone could provide a picture of a working cabling, i’d apreciate :)

thanks, RAF

d2k · March 22, 2003, 6:22am

Hey RAF

This is the pic from the walkthrough on the site…

HTH

Dan

jerash · March 22, 2003, 1:49pm

thanks thorsten, but i’d previously seen this picture. In fact i meant a “Photography” :-[

Because As i see in this picture (drawing) it’s like there is a lot of cables leaving the ainx4.

would someone open his MB and take a detailed photo ?

sorry for the mess.

raf

jerash · March 22, 2003, 1:51pm

what confuses me is the term “8 pots in a bundle”

I don’t see how i could connect only 8 pots together while there is only 1 0-5V out on the ainx4.

i hope its clear enough

RAf

T.K · March 22, 2003, 6:11pm

Problem is that I don’t know how to visualize it better.

Let’s take a look under my MB64 case:

Best Regards, Thorsten.

rogic · March 25, 2003, 6:43pm

This is all great guys, but you haven’t told me what to do about jittering :-/

Should I shorten cables? Try to move them as far as I can from Power Supply? Any hint?

Ian_Hurlock · March 26, 2003, 12:53pm

How smooth is your PS.

Got some fat cat caps on him ?

Ian

rogic · March 27, 2003, 12:07pm

Hi,

my MB64 differs from others - PS is on another board and 5V is delivered to the CORE from circuit with 7805, etc. Capacitor is 25v 3300uF, and the voltage to the CORE varies from 5.02-5.03V. Is this ok?

Another thing: I selected ‘snapshot at power on’ in vmidibox; When I monitor in midiox messages sent by MB on startup, I receive this:

TIMESTAMP IN PORT STATUS DATA1 DATA2 CHAN NOTE EVENT               
     13621 GMe --    176     0    89    1  ---  CC: Bank MSB          
     13621 GMe --    176     1    98    1  ---  CC: Modulation        

     13621 GMe --    176     3    92    1  ---  Control Change        
     13621 GMe --    176     4    91    1  ---  CC: Foot Controller   
     13621 GMe --    176     5    55    1  ---  CC: Portamento Time   
     13621 GMe --    176     6    26    1  ---  CC: Data Entry MSB    
     13621 GMe --    176     7    43    1  ---  CC: Volume            

     13621 GMe --    176     9    47    1  ---  Control Change        
     13621 GMe --    176    10   105    1  ---  CC: PAN               
     13631 GMe --    176    11    83    1  ---  CC: Expression        
     13631 GMe --    176    12    71    1  ---  Control Change        
     13631 GMe --    176    13    28    1  ---  Control Change        
     13631 GMe --    176    14    11    1  ---  Control Change        
     13631 GMe --    176    15     0    1  ---  Control Change        
     13631 GMe --    176    16    86    1  ---  Control Change        
     13631 GMe --    176    17     0    1  ---  Control Change        
     13631 GMe --    176    18     0    1  ---  Control Change        
     13631 GMe --    176    19     0    1  ---  Control Change        
     13631 GMe --    176    20     0    1  ---  Control Change        
     13641 GMe --    176    21     0    1  ---  CC: 21 (E-MU)         
     13641 GMe --    176    22     0    1  ---  CC: 22 (E-MU)         
     13641 GMe --    176    23     0    1  ---  CC: 23 (E-MU)         
     13641 GMe --    176    24     0    1  ---  CC: 24 (E-MU)         
     13641 GMe --    176    25     0    1  ---  Control Change        
     13641 GMe --    176    26     0    1  ---  Control Change        
     13641 GMe --    176    27     0    1  ---  Control Change        
     13641 GMe --    176    28     0    1  ---  Control Change        
     13641 GMe --    176    29     0    1  ---  Control Change        
     13651 GMe --    176    30     0    1  ---  Control Change        
     13651 GMe --    176    31     0    1  ---  Control Change

Why I don’t get states of pots #2 & #8 ???

T.K · March 28, 2003, 2:29am

It seems that this is a bug in the “snapshot after power-on” feature. It has been implemented on a very dirty way - possibly values will not be sent when the saved pot positions were the same like the current positions. I will check this with the next release…

The voltage level is superb! It would be interesting if you also notice jitter when you increase or decrease the input voltage to the voltage regulator (@J1! – I don’t mean the 5V behind the voltage regulator). Does your PSU allow to vary the voltage?

Best Regards, Thorsten.

rogic · March 28, 2003, 1:36pm

Thanks TK for the reply; This snapshot ‘bug’ is not so important for me - two pots not sending their state is not a problem at all, I just thought it may have something to do with jittering… but that’s a total electronics newbie assumption.

About voltage: you suggest that I change voltage after 7805? I’ll go to my friend (an expert - not dummy like me! :)) and try this idea…

thanks a lot

d2k · March 28, 2003, 1:44pm

Hey Rogic

About voltage: you suggest that I change voltage after 7805?

Before the voltage regulator (7805), so from J1… the 2 pins (J2) behind the 7805 are a +5v output, that could for instance, be used to power another core in a multicosre setup - details on this are on the core page on the site…

Some wallplugs allow u to vary the voltage, from say 7.5v-12v via a trim pot on the plug itself - I’m assuming T means this…

Best

Dan

rogic · March 28, 2003, 8:01pm

you mean to amplify voltage before 7805?

T.K · March 29, 2003, 7:42pm

Hi Rogic,

yes — very important — the PIC supply voltage should never exceed 5V, thats the job of the 7805, it limits (and regulates) the voltage to this level

Best Regards, Thorsten.