Can I get more volume from this circuit?

[jghfslk]

I just finished a pedal with a splitter and blend so I can put effects in series and parallel.  
I used this splitter:
schematic   http://www.muzique.com/lab/splitter.htm   
layout   http://tagboardeffects.blogspot.com/2014/08/amz-2-channel-splitter.html
and this mixer:
schematic   http://runoffgroove.com/splitter-blend.html
layout   http://www.sabrotone.com/?attachment_id=3039
I would like to get some more volume out of either the splitter or the mixer.  Is it possible without adding an additional circuit like an lpb-1?  I seem to get unity gain when using my effects in parallel but in series there is a noticeable drop in volume compared to bypass.
Anyone have any ideas?
Thanks!

[nocentelli]

Increase the 220k in the feedback loop of the mixer opamp (replace with a 100k + 500k pot in series)

[jghfslk]

Thanks for the reply!  Which 220k should be replaced?  I was thinking it was R6 but I have limited knowledge of how a lot of circuits work.  Would increasing the resistor in the feedback loop give me more volume for both outputs or just one?  Would I be better off changing the resistors just before the output on the splitter?

[nocentelli]

Increasing R6 will increase the level of whatever is in the loop: You cannot easily increase the level of the dry buffered signal without adding a few more components to the dry path buffer circuit.

I'm unclear what you mean about the volume level of parallel versus series: This splitter mixer blends dry signal with another effect in parallel.

[jghfslk]

My idea was to build a box that can have the option of having the effects in either series or parallel.  First my signal goes through the splitter.  Then I used this diagram to switch between series and parallel.  Finally I used the mixer to blend the effects and have the option to flip the polarity.  If I have effects plugged into the box in parallel mode and the effects are in bypass I get the same volume as when the whole circuit is in bypass mode.  If I am using the effects in series mode I get a noticeable volume drop I think because I am only using one of the outputs of the splitter.  I am thinking I will try to get more output from the outputs of the splitter but wasn't sure if that would give me any distortion.

[nocentelli]

jghfslk wrote

I used this diagram to switch between series and parallel.

You might need to share a diagram of how you did that.

[jghfslk]

Whoops..  I forgot to paste the link.  Here it is:  http://www.rhythmanddetonation.com/wp-content/uploads/2011/01/SERIES-PARALLEL.jpg

[jghfslk]

I think I will be good if I can get more volume out of the splitter:  http://tagboardeffects.blogspot.com/2014/08/amz-2-channel-splitter.html

Is it possible to get more volume out of this without major clipping?  Or is there a splitter that might be better suited for what I have in mind?  Would an op amp based circuit be better for achiving a higher clean volume?

[nocentelli]

jghfslk wrote

I think I will be good if I can get more volume out of the splitter:  http://tagboardeffects.blogspot.com/2014/08/amz-2-channel-splitter.html

Is it possible to get more volume out of this without major clipping?  Or is there a splitter that might be better suited for what I have in mind?  Would an op amp based circuit be better for achiving a higher clean volume?

The JFET used to split the signal is just a buffer, so can only be unity gain: You could change the layout to make it be a gain stage, but that requires some extra components, and it's not always easy to bias a JFET for lots of clean headroom and some gain, so opamps my be a better route.

[jghfslk]

I found one on this page that uses a TL072:  http://guitar-fx-layouts.42897.x6.nabble.com/Recommended-Simple-Splitter-td33403.html;cid=1501954657418-99#a33437

With there only being 2 resistors, would this circuit be capable of increased volume at the outputs? The description indicates that decreasing the resistors will reduce the brightness.

[nocentelli]

No, no extra gain available with that one either: For an opamp stage to have again of more than 1, there is usually a feedback resistor between inverting input and output.

[jghfslk]

Rats.. Do you happen to know of any splitters that use an op amp with a feedback resistor?  Or is it possible to mod one to add in a feedback resistor?

[strassercaster]

How much more gain do you need? Seems pretty complicated. I noticed subbing a jrc4559 was louder than a jrc4558 or tl072

[nocentelli]

jghfslk wrote

Rats.. Do you happen to know of any splitters that use an op amp with a feedback resistor?  Or is it possible to mod one to add in a feedback resistor?

 Something like the mxr microamp would make a decent booster/splitter, it's a pretty simple circuit.

[jghfslk]

I don't need a whole lot more..  The difference when using one of the outputs and bypass isn't massive but definitely noticeable.  I'll try to find a jrc4559 and give it a shot.  Thanks for the advice!

[jghfslk]

I'm looking at the layout for the microamp and I only see one output.  Do I need to modify the circuit to achieve 2 outputs for use as a splitter?

[nocentelli]

jghfslk wrote

I'm looking at the layout for the microamp and I only see one output.  Do I need to modify the circuit to achieve 2 outputs for use as a splitter?

Yes, but you would just need to add a second output cap along with the 470r and 100k pull down. You could alter the compact layout for the mxr here:

http://tagboardeffects.blogspot.co.uk/2010/10/mxr-microamp-compact-layout.html

...by adding a column on the left hand side, two extra cuts and those three extra components:



You would still have to deal with the issue that the gain control affects both outputs equally. You could alter the layout to have the gain fixed quite high (replace pot with a jumper or 10-22k resistor and add a separate volume pot for each output so you could adjust them independently. This would mean maybe not installing the 100k resistors and instead using two 100kA volume pots on each output.

I'm still unsure how you have integrated the splitter, mixer, series/parallel switch and bypass switches, and this is why I'm not 100% sure on the best arrangement for all this. Am I right that you have the guitar going straight into the splitter (no bypass) then the two separate outputs feeding.... what? The series parallel diagram has only a single input. I don't understand how you can have a series setting if the guitar is split into two parallel paths before it entounters the switch, or how you can have bypass at all if you've wired the two outputs of the splitter direct to EFFECT A in and EFFECT B in. If you could sketch a layout of the arrangement of the separate parts (MS paint is fine) that would help a lot.

[jghfslk]

I built the microamp and that gave me the extra volume I need!  I used a trimmer instead of an output pot for the microamp.  Here is how I wired everything:  

http://s1126.photobucket.com/user/jghfslk/media/Series%20Parallel_zpsptvlda2h.png.html

Sorry for the poor quality drawing. I hope it isn't too difficult to follow.  I also forgot to draw it on the diagram but I put a volume pot between Return 1 and the series/parallel switch and Return 2 and the ROG Input.  I also a standard offboard wiring to bypass everything.

Thank you for all of the help!