True bypass looper

[TomLoux]

Okay so it's my first post here and I tried to use the search... I guess somewhere someone already asked this.

I'm in the middle of sourcing my parts for a true bypass looper and after reading up on some stuff on the interwebs.
Apparently adding in a buffer in the looper is better for the sound preservation, with the addition of cables.

I'm not 100% sure how it works. If I make 10 inputs and put a separate buffer pedal in the first looper slot is the problem fixed then ?
Or is it better to use a PCB like this one : http://www.musikding.de/The-Buffer-Buffer-pcb and wire it in.

Now if I would go for the second one (pcb) how would I go about wiring it into the looper layout ?

So I'm using this layout from another part of the forum:


Thank you !

[Nocentelli]

A buffer should generally go at the start of a signal chain, it produces a low impedance output that reduces treble loss due to cable capacitance. So if you had a 3 metre cable, a string of true bypass pedals into a buffer into some more pedals then to an amp, the treble loss would only be reduced downstream of the buffer and the cable and pedals before the buffer would still shave off some high end. If you have a BOSS or other buffered bypass pedal first in your chain, any other buffer is not necessary as the signal will be low impedance already.

If you put a buffer in the first loop, every other active loop will be buffered IF the first loop is on. It would make more sense to place the buffer between the output of the master bypass and the input to the first (order switcher) foot switch, so when you activate the whole looper pedal by switching the master switch, anything downstream is buffered. This also means your true bypass looper is actually true bypass (if that's important).

[TomLoux]

Great, yeah that was what I was thinking. I would love to build it into the layout I gave above.

Any idea how I should wire this http://diy.musikding.de/wp-content/uploads/2013/06/bufferwire.pdf buffer pcb into the schematic. I'm guessing
i'm right about choosing this buffer type? Another question is the fact that they state that there are 3 types of variations ,you can build it as a germanium-, silicon-, or FET-Version.
Which one should I take?

Thank you for the help

I'm from belgium so any other pcb kit that is available for shipping to Belgium is ok for me !

[Nocentelli]

I think a FET buffer has the lowest impedance output, but a silicon BJT circuit is probably good enough. Opamp buffers are also popular. I've no idea why anyone would use a germanium transistor for a buffer, unless you had loads spare and wanted to use them up. If you use a PCB like the you posted, just omit the jacks, wire the "send" from the master bypass switch to the input pad of the buffer, and wire the output pad of the buffer to the input of the order switch. If you're not bothered about an order switch, you could just omit it entirely and wire the buffer output direct to the input of the first loop bypass switch instead. You also need to connect the power wires to the power, of course.

[TomLoux]

Okay,

So I get all you are talking about. But the only thing I don't know where to wire the in and the out now.
One other thing I'm not sure about is of the ground on the right side of the pcb is wired okay.

I'm going to leave the led out anyway. As you said I would like to wire the buffer to the master bypass switch...

3-loop-w-tuner-out-master-bypass copy.jpg

thank you !

[Nocentelli]

My apologies, i couldn't read the layout labels on my phone: i have confused you by referring to a loop order switch that doesn't exist. i meant instead the tuner/mute switch. The guitar jack input sends the purple wire carrying the guitar signal to the master switch. This switch either a) sends the guitar direct to the output (true bypsss and the switch simultanuously grounds the "send" lug that goes to the tuner/mute switch and all the loops to kill induced noise) or b) sends the guitar on to the tuner/mute switch. it's at THIS point you break the connection and insert the buffer.

[TomLoux]

So I'm guessing the PCB should go in In Between the tuner mute and the master bypass ?

If you have any time could you maybe do the wires in paint. Right now I'm a bit confused
I'll try to make a quick photoshop of what you are saying but I'm going off on a limb that its going to be wrong

[TomLoux]

I'm guessing this should be the right position ?

From what I understand you are saying is the buffer should be there. The master switches wire going to the tuner 3PDT should first go into the IN from the buffer and the out should go where the original wire went ? Or am I completely wrong on this ?

No the only thing i still need to know is where I need to put the ground wires in this layout and the 9V + I guess The 9V+ just has to go to the red wire and the grounds should be connected into the ground loop ?
Only thing is is I'm not sure where the ground wires should go in that loop. Or is that quite irrelevant. 4

3-loop-w-tuner-out-master-bypass not wired.JPG

[Nocentelli]

[edit] Spot on, that's it. [edit/]

true bypass but buffered_tuner_mute_looper.png

this is a nice little set-up, thanks for the idea. i made a much simpler, three footswitch job with just two loops but with a bypass each, and a switch in the middle that swaps series order A->B or B->A: You should maybe think about including at least one of these, it can be very useful. Mine's not buffered though, i'm now thinking about putting a jfet buffer on a toggle switch on each loop - not worth doing on 10 individual loops, though i imagine.

[TomLoux]

Gotta love the good old forums and sharing the information on the interwebs !
Thank you for the input !!

You made my day ^^

[TomLoux]

One more thing, now I'm gathering all the parts and the 10k resistors are that are used on the leds is the only thing i'm doubting a bit.

I am looking in the musikding shop http://www.musikding.de/Resistors

And i'm guessing it is the first tab ? an then the 4th tab 10 k0hm ? right
10k is 10 k0hm ?

So I want to select the first ones ? 10k metal film 1%

Am I right about this ?

[Nocentelli]

10k = 10 kOhm = 10 kilohm

The 0.6W 1% metal film ones will be fine, the're overkill in a pedal really. 0.25W are usually used in pedals, more because they're a bit smaller and cheaper and have the power rating sufficient for a 9 volt circuit but if you're not buying hundreds and don't need to squish them into a tight pcb it's not an issue. metal film are more expensive than carbon film, but supposedly quieter and have a better tolerance, none of which is at all relevant for use as LED current limiting resistors though.