mod al boss bf-2 flanger

[TheSatch]

ciao ragazzi,si può moddare il bf-2?in giro non ho trovato nulla se non qualcuno che lo modifica a pagamento,guardandosi bene dal dire cosa cambia   
vorrei renderlo un pò più flangioso...vorrei migliorare l'attacco e rendere i controlli un pò più sensibili. 
secondo voi che si può fare?

questo è lo schema

http://www.schematicheaven.com/effects/ ... langer.pdf

[Gila_Crisis]

si che si puo', io l'ho fatto è il risultato non è male, eccoti le mod fattibili
ho fatto a), d), e), funzionano bene,ma non mi ricordo piu' i valori che ho messo ma potrei controllare. interessante sembra la mod in fondo di cambiare C8 e C9 per avere un suono simile al MXR. ma non l'ho provata.

a) C27 and C28 make up a non-polarized 16.5uf capacitor which sets the speed range.  If the capacitance value is reduced, the speed range goes higher.  Faster speed can produce an effect that sounds very much like a ring modulator.  I would suggest a pair of 4.7uf caps, back to back, as a suitable replacement.

b) Maximum flanging effect needs a 50/50 balance between delay and clean signal, but sometimes you want just a taste of flanging.  If the value of R29 is increased, the balance is shifted in favour of clean.  If you replaced R29 with a 22k fixed resistor, and a 100k pot, wired as a variable resistor (2 lugs, not all 3), you would be able to get everything from a *perfect* 50/50 balance to a much softer flanging effect, even with very high regen/res.

c) R11, D3, and D4 form a soft limiter, to keep high regeneration/resonance signals from overloading the delay chip.  If you shunt/short R11, the clipping of D3/D4 becomes "harder" and introduces more harmonic content.  If you want to experiment with more interesting high regeneration signals, solder in a wire bridge across R11 on the copper side of the PCB, turn up VR5 a bit higher (VR5 is normally set so that turning up the RES control all the way puts you just below the point of oscillation).

d) C7 sets the lower bandwidth point (bass rolloff) of the regeneration signal.  If you make it smaller in value, this will make high regen/res settings sound less metallic.  A value of .01uf might be a good place to start.

e)  The depth contol (VR2) adjusts the balance of voltages coming from the LFO and the Manual control to drive the clock (IC4).  VR7 is used to adjust or fine tune the delay time by adding (or maybe subtracting) a small DC voltage on top of whatever comes through VR2/R48.  C30 sets the delay range of the clock circuit.  Values larger than 47pf will set the minimum delay time much longer.  Smaller values will reduce the minimum delay time.  You can change the sound of the pedal by changing the range of delays it can produce.  Try a cap of 39pf and see if you like it.  If there are problems with the sweep, you may be able to fix them with VR7.  Alternatively, if you are able to find an MN3209 chip somewhere, you can take the MN3207 out and replace it with the MN3209 for shorter (X/4) delay times and more of a "jet plane" sound.

f) Vibrato is created when you use ONLY the delay signal, and leave out the clean signal.  If you lift one end of R28, that will prevent the clean signal from being mixed in with the delay signal, and give vibrato.  Unfortunately, because of how bypass is done in this pedal, this means that when you try to bypass the pedal, there will be NO sound coming out.
Solution: In modulation effects where dry and wet are combined, you can cancel the effect bi simply lifting the connection between the wet path and mixing stage.  In the BF2, Q4 fulfills this function.

This means that while the "flip" part of the circuit is used to enable/disable the gate of a FET and an LED, the "flop" part of the circuit does nothing.  We *can* put this section to work, though.

To produce vibrato, lifting one end of R28 will kill the dry signal and get you vibrato.  When you hit the footswitch, though, there is no "flop" action to restore the bypassed/clean signal....but there COULD be..

Imagine that there is a second 47k resistor and a FET in series with each other, and in parallel with R28.  Now, also imagine that there is a 1M resistor, .047uf cap, and diode connecting the gate of that FET to the junction of R55 and Q9, exactly the same way a resistor, cap, diode combo connects the gate of Q4 to the junction of R56/Q10.  Step on the footswithc once, and the led comes on and Q4 goes low resistance.  Step again and Q4 and the LED go off and our new added FET turns on and provides a low resistance path for the clean signal to the added parallel resistor and the mixing stage.  More importantly for our purposes, that path exists independent of the toggle switch.  So, if the toggle is closed, the added FET/resistor simply duplicate what is already there when you step on the footswitch.  If the toggle is open, then cancelling the wet signal also results in providing a dry signal.

FYI, the C7, C21 mods have no effect at all when the res/regen is off.
I suggest you look at the BF-2B which does have less metalic sound.  Roughly,
- a delay chip with less (512) stages.  this reduces the delay time
- C7 mod (47nF to 10nF)
- C6 is reduced from 47nF to 15nF.
Now reducing the delay time can significantly reduce the metalicness.    One way to approximate this is to reduce C30 (47pF).  Unfortunately the clock frequencies are already pretty high so it's probably unwise to use a small C30 like 22pF to drop the delay to the BF-2B level.  You could try 33pF and cross your fingers.
Tune the C6 mod first to your taste with res/regen off - try say 22nF or 33nF.
Then Tune C7 using some res/regen.
Another mod is to play with C8 and C9.  For example you can get the filters to be quite close to the mxr flanger by changing only two caps:  C8 from 12nF to 2.2nF, and change C9 from 150pF to 1nF.

In case you are still interested in attemping the mod on the BF-2, I studied the schematic available from the Free Information Society and came to the following changes in order to achieve the increased sweep after replacing the BBD for a 512 stage MN3204:
1) IC5 needs to be replaced with a full rail-to-rail output opamp like the TLC2262, TLC2272 or MAX492, to name some.
2) Then, resistors R36 (180k) and R37 (220k) need to be swapped with each other to increase the output voltage range of the LFO.
The use of a rail-to-rail output opamp is necessary, otherwise the LFO won't work with the extended output voltage range.  Eventually, but not necessarily, VR7 might need a slight adjustment in order to center the new range of the sweep.
In summary, the required changes are pretty simple, except for the difficulty in getting the MN3204 and TLC2262 ICs  (WHICH YOU HAVE ALREADY DONE!)
:

[TheSatch]

grazie delle info! l'ho aperto,ma ci sono tanti di quei componenti che non si capisce una mazza  i nomi sn tutti comperti?non è che ti trovi un layout,dove ci leggono i nomi dei componenti e dove posizionati?

si che si puo', io l'ho fatto è il risultato non è male, eccoti le mod fattibili
ho fatto a), d), e), funzionano bene,ma non mi ricordo piu' i valori che ho messo ma potrei controllare. interessante sembra la mod in fondo di cambiare C8 e C9 per avere un suono simile al MXR. ma non l'ho provata.

a) C27 and C28 make up a non-polarized 16.5uf capacitor which sets the speed range.  If the capacitance value is reduced, the speed range goes higher.  Faster speed can produce an effect that sounds very much like a ring modulator.  I would suggest a pair of 4.7uf caps, back to back, as a suitable replacement.

b) Maximum flanging effect needs a 50/50 balance between delay and clean signal, but sometimes you want just a taste of flanging.  If the value of R29 is increased, the balance is shifted in favour of clean.  If you replaced R29 with a 22k fixed resistor, and a 100k pot, wired as a variable resistor (2 lugs, not all 3), you would be able to get everything from a *perfect* 50/50 balance to a much softer flanging effect, even with very high regen/res.

c) R11, D3, and D4 form a soft limiter, to keep high regeneration/resonance signals from overloading the delay chip.  If you shunt/short R11, the clipping of D3/D4 becomes "harder" and introduces more harmonic content.  If you want to experiment with more interesting high regeneration signals, solder in a wire bridge across R11 on the copper side of the PCB, turn up VR5 a bit higher (VR5 is normally set so that turning up the RES control all the way puts you just below the point of oscillation).

d) C7 sets the lower bandwidth point (bass rolloff) of the regeneration signal.  If you make it smaller in value, this will make high regen/res settings sound less metallic.  A value of .01uf might be a good place to start.

e)  The depth contol (VR2) adjusts the balance of voltages coming from the LFO and the Manual control to drive the clock (IC4).  VR7 is used to adjust or fine tune the delay time by adding (or maybe subtracting) a small DC voltage on top of whatever comes through VR2/R48.  C30 sets the delay range of the clock circuit.  Values larger than 47pf will set the minimum delay time much longer.  Smaller values will reduce the minimum delay time.  You can change the sound of the pedal by changing the range of delays it can produce.  Try a cap of 39pf and see if you like it.  If there are problems with the sweep, you may be able to fix them with VR7.  Alternatively, if you are able to find an MN3209 chip somewhere, you can take the MN3207 out and replace it with the MN3209 for shorter (X/4) delay times and more of a "jet plane" sound.

f) Vibrato is created when you use ONLY the delay signal, and leave out the clean signal.  If you lift one end of R28, that will prevent the clean signal from being mixed in with the delay signal, and give vibrato.  Unfortunately, because of how bypass is done in this pedal, this means that when you try to bypass the pedal, there will be NO sound coming out.
Solution: In modulation effects where dry and wet are combined, you can cancel the effect bi simply lifting the connection between the wet path and mixing stage.  In the BF2, Q4 fulfills this function.

This means that while the "flip" part of the circuit is used to enable/disable the gate of a FET and an LED, the "flop" part of the circuit does nothing.  We *can* put this section to work, though.

To produce vibrato, lifting one end of R28 will kill the dry signal and get you vibrato.  When you hit the footswitch, though, there is no "flop" action to restore the bypassed/clean signal....but there COULD be..

Imagine that there is a second 47k resistor and a FET in series with each other, and in parallel with R28.  Now, also imagine that there is a 1M resistor, .047uf cap, and diode connecting the gate of that FET to the junction of R55 and Q9, exactly the same way a resistor, cap, diode combo connects the gate of Q4 to the junction of R56/Q10.  Step on the footswithc once, and the led comes on and Q4 goes low resistance.  Step again and Q4 and the LED go off and our new added FET turns on and provides a low resistance path for the clean signal to the added parallel resistor and the mixing stage.  More importantly for our purposes, that path exists independent of the toggle switch.  So, if the toggle is closed, the added FET/resistor simply duplicate what is already there when you step on the footswitch.  If the toggle is open, then cancelling the wet signal also results in providing a dry signal.

FYI, the C7, C21 mods have no effect at all when the res/regen is off.
I suggest you look at the BF-2B which does have less metalic sound.  Roughly,
- a delay chip with less (512) stages.  this reduces the delay time
- C7 mod (47nF to 10nF)
- C6 is reduced from 47nF to 15nF.
Now reducing the delay time can significantly reduce the metalicness.    One way to approximate this is to reduce C30 (47pF).  Unfortunately the clock frequencies are already pretty high so it's probably unwise to use a small C30 like 22pF to drop the delay to the BF-2B level.  You could try 33pF and cross your fingers.
Tune the C6 mod first to your taste with res/regen off - try say 22nF or 33nF.
Then Tune C7 using some res/regen.
Another mod is to play with C8 and C9.   For example you can get the filters to be quite close to the mxr flanger by changing only two caps:  C8 from 12nF to 2.2nF, and change C9 from 150pF to 1nF.

In case you are still interested in attemping the mod on the BF-2, I studied the schematic available from the Free Information Society and came to the following changes in order to achieve the increased sweep after replacing the BBD for a 512 stage MN3204:
1) IC5 needs to be replaced with a full rail-to-rail output opamp like the TLC2262, TLC2272 or MAX492, to name some.
2) Then, resistors R36 (180k) and R37 (220k) need to be swapped with each other to increase the output voltage range of the LFO.
The use of a rail-to-rail output opamp is necessary, otherwise the LFO won't work with the extended output voltage range.  Eventually, but not necessarily, VR7 might need a slight adjustment in order to center the new range of the sweep.
In summary, the required changes are pretty simple, except for the difficulty in getting the MN3204 and TLC2262 ICs  (WHICH YOU HAVE ALREADY DONE!)
:

[Gila_Crisis]

per capire dove è cosa guarda qui:

http://www.godiksennet.com/images/sch/BF2PG2.jpg

c'è un disegno della pcb con marcati tutti gli elementi 

[TheSatch]

per capire dove è cosa guarda qui:

http://www.godiksennet.com/images/sch/BF2PG2.jpg

c'è un disegno della pcb con marcati tutti gli elementi 

grazie ancora! 
non è che conosci anche qualche mod al ch-1?

[SghioHV88]

io invece posso cadere totalmente dalle nuvole?

siccome volevo comprarmene uno anche io, quale flanger mi consigliate?
il boss l'avevo provato ed in effetti ci sarebbe da migliorarlo un pò...ma siccome non so distinguere una resistenza da un diodo mi devo accontentare...o per lo mendo quale secondo voi sarebbe la miglior base di partenza?

PS se qualcuno ha una buona occasione per le mani ci si può mettere d'accordo...

[TheSatch]

io invece posso cadere totalmente dalle nuvole?

siccome volevo comprarmene uno anche io, quale flanger mi consigliate?
il boss l'avevo provato ed in effetti ci sarebbe da migliorarlo un pò...ma siccome non so distinguere una resistenza da un diodo mi devo accontentare...o per lo mendo quale secondo voi sarebbe la miglior base di partenza?

PS se qualcuno ha una buona occasione per le mani ci si può mettere d'accordo...

dai,il bf2 è carino!  poi è analogico a differenza del bf3 quindi lo puoi moddare 
altrimenti prendi l'mxr e stai a posto
se non ne sai niente ci sn degli ottimi tutorial  su questo sito e poi io ho imparato un sacco di cose potando qui   

[Boss]

Non sapevo il bf3 fosse digitale... comunque dove sta finendo il mondo dei pedali!!!
Comunque a sentirlo non pare, pensa che lo volevo comprare...

[Gila_Crisis]

modifiche per il CH1 non ne conosco. prova a cercare su diystompboxes, magari li troviqualcosa

[TheSatch]

-ho fatto la mxr mod e va bene 
-ho messo in C7 un cap da 4.7 nF in poliestere e non fa più quell'effetto metallico con res e manual al massimo 
-ho messo un cap da 56pF in C30,molto jet plane 
-la modifica in c27 e c28 l'ho fatta e sn tornato indietro, secondo me è peggiorativa

dopo ho fatto un regolata ai trimmer ed il suono miglira ancora e dopo ho sostituito questi condensatori elettrolitici con condensatori in poliestere di uguale valore :
-C2,C24 =>1uF poliestere
-C17,C20  => 0,22 uF poliestere

poi ho messo :
C1 => 0,1 uF poliestere
C3 => 10nF poliestere

dopo ho cambiato i 2 jrc4558 (IC1 ed IC2) con:
-IC1 => TL072
-IC2 => TL062

fine modifica
l'ho chiuso per evitare che mi venisse in mente qualcos'altro 

[Gila_Crisis]

fikus!
ma che ci guadagni a cambiare gli opamp???? cambiando C1 e C3 che risultato hai ottenuto?

uh uh.... mi sa che devo riprendere in mano sto pedale pure io... ci sono ancora 2-3 modifichette da fare