buff and blend that runs off 12 volts ?

[petey twofinger]

going to be doing a mini amp with a spring reverb in it . using the esp tank driver and i figured i would go with a buff and blend for a mix control .

this amp runs off 12 volts , the buff and blend here is 9 volts .

http://www.aronnelson.com/gallery/main.php/v/Toneys-Album/Buff_n_Blend.png.html

what would i have to change in the circuit to run it off of 12 volts ?

the esp reverb driver circuit uses 15 volts so i was thinking of trying a charge pump for that ...

http://sound.westhost.com/p34-fig3.gif

figure 3 on this page

http://sound.westhost.com/project34.htm

not really sure on any of this though , if the gain is gonna "match up" , and also if i need bipolar 15 volts . it appears to me just 15 volts should work , but ...

any recommendations or "you are doing it wrongs" would be much appreciated 

[Mark Hammer]

Technically, if its the buff-n-blend I'm thinking of (can't see the schem from work, but I'm assuming its Sean McLennan's), you don't have to do anything other than assuring the caps are rated at least 16v.  The TL074 will happily run off 12v, and the Vref is derived by simply dividing the V+ in half.  15V will also work just fine, but you'll want caps rated at 25v for that.

[petey twofinger]

thanks for the info , although i haven't found that layout yet , i will look forit , its just that i do not have extra tl074 and i do have plenty of j201 / mpf102 which is what is in the link up there .

the link i have is a vero only , although i would like to see a schemo for this , just so can see whats "goin on" .

[kaycee]

Jfet Buff'n'Blend by Joel Purkis will run fine off of 12 or 15volts with just the same provisio on capacitor voltage ratings. You won't find a vero for Sean's one (at least i couldn't), there is a perf/PCB layout in the vault - you can do it on perf but its kind of messy - I speak from experience here!

[Toney]

Here you go:







   


Note, achtung warning etc.
I made this a few years ago but  have never build it.
Please check it against the schem.

[Mark Hammer]

Sean's circuit works great.  I made one recently for a buddy, who needed to mix an effect with clean, but also wanted to be able to compensate for overall level reduction created by notches.  I gave the output stage a bit of gain (4x, I think), and stuck a 100k volume pot on the output.  Normalizing the send and receive jacks, so that the one automatically feeds the other, if nothing is plugged in, turns it into a clean booster (though with modest boost).  It has a 3PDT master bypass, which allows him to use it as an A/B/Y if he feels like it.  How?  Well, in bypass mode, you g straight from input to output.  When engaged, if you only use the send jack, that can be your alternate output.  Depending on how the output volume knob is set, that alternate output can co-occur with no signal from the "mix/blend" output jack (i.e., fully attenuated), or it can be a second output of equal or even greater level.

VERY flexible signal routing.  Kudos to Sean.

[karter2000]

Yep, big +1 to the B. Blender.  I've built a few, and they always work great.  A question for you Mark.  How did you increase the gain of the output stage?  Even though the circuit works great, I've always been confused by the notch issue, and what to do about it.  I've always thought it was a phase issue between the effect and dry.

Thanks!

Sean's circuit works great.  I made one recently for a buddy, who needed to mix an effect with clean, but also wanted to be able to compensate for overall level reduction created by notches.  I gave the output stage a bit of gain (4x, I think), and stuck a 100k volume pot on the output.  Normalizing the send and receive jacks, so that the one automatically feeds the other, if nothing is plugged in, turns it into a clean booster (though with modest boost).  It has a 3PDT master bypass, which allows him to use it as an A/B/Y if he feels like it.  How?  Well, in bypass mode, you g straight from input to output.  When engaged, if you only use the send jack, that can be your alternate output.  Depending on how the output volume knob is set, that alternate output can co-occur with no signal from the "mix/blend" output jack (i.e., fully attenuated), or it can be a second output of equal or even greater level.

VERY flexible signal routing.  Kudos to Sean.