R1 value in Reverberation Machine + how to kill the dry signal?

[BassVD]

Hi guys,

Quick question: there is a resistor in the layout for the Death By Audio Reverberation Machine, but what does it change soundwise? It is suggested to test values between 1k and 10k, but does it change the sound or dynamics or something else? What are the pros and/or cons for a higher or lower value?

Also: is there an easy way to kill the dry signal while the effect is engaged?

Link to layout: http://tagboardeffects.blogspot.be/2015/10/death-by-audio-reverberation-machine.html

Thanks!

[Addy Bart]

The original value listed on the posted schematic was 100k but I (and others here) felt the sunshine setting didn't sound right - it was very tame. So I jumpered that resistor and it sprang to life. I settled on 4k7 as volume wise, it matches well with the dark star setting but you could probably lose the resistor altogether and just jumper it... All depends on your set up I guess.

If you want a more subtle reverb you could go higher than the suggested range, but imo this pedal isn't about hi-fi pristine reverb. That said, it's my favourite reverb, apart from the spring in my amp.

[BassVD]

Thanks! That's some useful info that should be added to the layout page. :)

Now, is there some way to kill the dry signal at the flick of a switch?

[Addy Bart]

I'm not sure if that's possible or not with the Belton bricks... Perhaps someone can say?
With the blend pot maxed out its really wet though :-)

[induction]

Killing the dry signal with the Belton reverbs is pretty easy. There's a wet-only path that goes from the input op-amp through the brick to the output mixer, and a parallel dry-only path that goes from the input op-amp to the output mixer. Just interrupt the dry path and you get wet signal only.

The two tricks to it are avoiding popping and working it into the vero. The simplest way I see to do both would be to make the input side of the 100k dry-path input resistor (the leg attached to the IN node) switchable between the IN node and a 2M2 to ground.

Here's how:
1. Put two cuts in the top row: one just to the right of R1, and another one directly above the voltage regulator.
2. Move the top leg of the 100k (the one next to the regulator) to the top row.
3. Attach lug 2 of an SPDT to the only remaining open hole on the top row between the two new cuts.
4. Attach lug 1 of the SPDT to the IN row (the second hole from the right is convenient).
5. Attach one leg of a 2M2 in the top row, just right of the cut above the regulator.
6. Attach the other leg of the 2M2 in the 5th row from the top, just right of the ground leg ('G') of the regulator.
7. Attach lug 3 of the SPDT just above the +9V wire.

There is no input pulldown resistor on the layout, so it might still pop when you switch to dry-kill. If so, you'll need to put another 2M2 between the input node and ground. You can fit one just to the left of the 100k dry input resistor, but it will have to stand unless you use a small one. A 1/8-watt one should fit laying down.

[Addy Bart]

Thanks for the detailed and informative reply, induction! If I make another one of these, I might give that a try :)

[BassVD]

Wow, thanks for the elaborate reply, induction! That probably couldn't have been any easier, haha!
Addy Bart: yeah I know, but for my purposes I like to have a kill-dry option on reverbs. I'm throwing an SPDT footswitch in, that way I can stomp my way into reverb-galore, haha!

I still have to get round to building the Reverberation Machine though (prolly at the end of the week).

[traktop]

The 100k resistor should be the one located at "sunshine" network path, (R12), not R1, which sits first at the dry path, right?

Does anybody know how to get more saturation with the altitude knob? I guess that must be something related with TLC27M4ALN U2 feedback loop network, but I couldn´t managed to figure it out.

I want to tame the dry signal low frequencies response as well. This effect works great on a twin reverb kind of amp, but was way too much for my el34 british hiwatt.
Maybe upping the 33nf input cap, (C1)...?

Here are some picture of the little monster I built:


I made a "dual control" mod which allows me having 2 different settings at a stomp switch, (actually 2 stompswitches, since I couln´t find a 6pdt stomp switch...)

[Addy Bart]

Yes, it's R12 in the schematic.

[traktop]

I thing I´m just going to cut the resistor body and solder a wire to both remaining legs, so I don´t have to mess with the board too much, thanks.

[Addy Bart]

I think you can even skip cutting the resistor and just jumper it with a small wire.

[traktop]

Really? I was on it, when I decided taking a look to this thread first, so not too late
Any idea about dry signal low frequencies attenuation and altitude pot giving more saturation?
Cheers, Gilberto.

[BassVD]

I'm also interested in knowing how to get more saturation out of it.
My telecaster doesn't have that much output. My guess is that something like humbuckers (with more output than your average single coil) will get more distorted sounds in combination with the altitude knob.

Also, about the R1/R12 thing: I jumpered that one. I tried a 5.6k resistor, but I really liked the superbright tone I got when I used a jumper. Result: I ditched the resistor. A solution might be to wire a 10k trimpot as a variable resistor to change it to your liking.

[traktop]

I´ve just jumpered the resistor and now I´ve got the sunshine reverb festival over here!!! Actually it´s too much as it starts distorting and oscillating past 10 o´clock. So maybe it would be interesting using trimmers even on the dark setting to fine tune both.
About the humbucker thing: My reference for this pedal has always been this video:
Look at this guy and his single coil jaguar... I don´t know about you, but with my strat and cranked altitude knob,  I´m not even getting what this dude is getting with the knob at 9 o´clock, (anyway, I thing a nice mod for this would be a linear taper for the altitude knob instead the antilog, since I find it don´t do much from 9 o´clock in advance...).
A

[Addy Bart]

Trimpots on both circuits sounds like a cool idea!
Jumpering the resistor made the pedal much louder but alas I didn't play around with the altitude pot for very long before I began trying out lower value resistors. When I get some time, I'll try again... Curious if it can get that dirty when jumpered? That particular YouTube demo sounded way more fuzzy than mine does at the moment.

[Addy Bart]

BassVD and traktop... Have you tried jumpering the 68k resistor? I think the saturation we are hearing in the YouTube link is coming from overloading the op amp and my hunch is that that is the resistor that limits the input level. I'm not able to try it myself for a week or so... If you can try it and report back, that would be great.

[BassVD]

Thanks for the tip, Addy Bart!
Will try it when I'm less busy, I'm just swamped with work and stuff these days.
I might have the time to do it next weekend.

Also, trimpots on both circuits are an exquisite idea.

[BetterOffShred]

I'm Glad I checked this out.. I was about to build this pedal.  Too bad they want $15 for a Belton brick.. Oh well.  It's still cheaper than buying the pedal and I get to build it myself right?  

Any other notable mods for this Pedal?  

-Brett

[Addy Bart]

Hi traktop! If you want to see if increasing the input cap solves your bass issue, try soldering another capacitor to the legs of the 33nf that's already there. Better still, use some crocodile clips to test it out. Should be pretty easy. Let us know if it helps. Cheers :-)

[traktop]

Addy Bart wrote

BassVD and traktop... Have you tried jumpering the 68k resistor?

Busy right now with a couple o muff builds. Will try it as soon as I´m done, thanks.
One thing: I thought that opamps maximum gain were obtained with zero negative feedback, so wouldn´t removing the 68k resistor do the opposite? (correct me if I´m wrong cause maybe I´m talking nonsense here...).
Cheers Gilbert.