A Spring Reverb using the ROG Splitter-Blend?

[Uma Floresta]

So I was thinking, the ROG Splitter-Blend would make a good platform for a spring reverb. Say, on the "green" side, send and return are simply connected. On the "red" side, send goes into an LM386N driver, which has a low impedance output to drive the springs. From the springs it goes into a simple recovery stage, and then into the "red" return, so you could mix the dry and reverberated signals.

And of course pre and post reverb filtering and tone controls could be added to the heart's content, as well as a volume control for the strength of signal sent to the springs.

Thoughts?

http://www.runoffgroove.com/splitter-blend.html

[Uma Floresta]

Any thoughts? Does this seem feasible, or am I missing something?

[sean k]

Totally feasible, two loops and a phase reverse switch with a mix pot thrown in.

I built this years ago and recently found it again, the ROG looper, and lent it out to a guy who said it didn't work. Once I got it home and pulled the back off I didn't know the schematic but with your promp I now know where I got it from. Thanks for that!

[Uma Floresta]

Totally feasible, two loops and a phase reverse switch with a mix pot thrown in.

I built this years ago and recently found it again, the ROG looper, and lent it out to a guy who said it didn't work. Once I got it home and pulled the back off I didn't know the schematic but with your promp I now know where I got it from. Thanks for that!

Cool!

[Uma Floresta]

Here's a Frankenstein schematic, stitched together from various designs:

[Uma Floresta]

I'm sure many of these non ROG values might need tweaking.

[johnadon]

I did something similar just this week did just this with the Splitter/Blend although I have a discrete reverb unit based on the project at Elliott Sound. ( http://sound.westhost.com/project34.htm ) I put a switch into the Elliott Sound project to take the dry signal in or out. It's quite fun with the Splitter/Blend and I imagine having it hard wired into the circuit would be equally fun.

[Uma Floresta]

I did something similar just this week did just this with the Splitter/Blend although I have a discrete reverb unit based on the project at Elliott Sound. ( http://sound.westhost.com/project34.htm ) I put a switch into the Elliott Sound project to take the dry signal in or out. It's quite fun with the Splitter/Blend and I imagine having it hard wired into the circuit would be equally fun.

Cool! How do you like the  sound of that reverb?

[sean k]

I think the only thing I'd do is use the top opamps for an FX send/return seeing that you have the phase reversal there otherwise I'd figure what kind of phase ended up at the mix pot and either invert one opamp at the top and remove the phase thing and the j-fet and forget about send and return. As well I'd try and simplify the gain recovery and Ub2 by having a simpler passive high pass straight off the tank and maybe a little gain on the feedback of Ub2 to do your recovery or why not just use Ub2 with a tone control accros the top of the feedback.

What you've got should work by why not make things a little easier and simpler and learn a bit as you go. I'd look at the first gain stage in an 808 with it's bass roll-off and use that as a straight recovery stage. I think they mid boost with a bass roll-off and the pico cap so I'd use the bass roll-off and scrape the cap and diodes and then make the gain pot smaller and have it's wiper with a pico cap to ground... or maybe it's to bias votage. That way you have bass roll-off and treble boost in one.

But take this advice with a big pinch of salt because it's a long time since I've been near the 808 schematic but from memory there's lots of info in these forums about tone shaping the first stage in there.

[johnadon]

I love the sound of the Elliot Sound circuit and it's pretty tweakable. I was thinking earlier, though, about the fact that it requires a bipolar power supply. I don't know much about power supplies, so I don't know if it would work with a unipolar power supply as the Splitter/Blend if it's all in one circuit.

And to demonstrate my lack of understanding of power supplies, I'm getting ready to post another thread on just that subject. 

[Uma Floresta]

I love the sound of the Elliot Sound circuit and it's pretty tweakable. I was thinking earlier, though, about the fact that it requires a bipolar power supply. I don't know much about power supplies, so I don't know if it would work with a unipolar power supply as the Splitter/Blend if it's all in one circuit.

And to demonstrate my lack of understanding of power supplies, I'm getting ready to post another thread on just that subject. 

Would the bipolar power supply have anything to do with the transistors? I don't know anything about bipolar power supplies, really.

[johnadon]

I really don't want to say too much about power supplies, especially right at the moment, considering a problem I'm having trying to eliminate a transformer from a - you guessed it! - bipolar power supply. My unsuccessful attempt to do this indicates a genuine deficiency in my knowledge of power supplies and I don't want to lead anyone down a path that shouldn't be taken. There's nothing inherently scary about bipolar power supplies (transformers running off mains, yes, but bipolar supplies in general, no), but I'm just not qualified to say much. There is a good article on RG's site about power supplies: http://www.geofex.com/Article_Folders/Power-supplies/powersup.htm

Can anyone else help?

[sean k]

Wallvoltage is a bit dangerous but once it hits that 12V its a baby so just cover your ass on the wall voltage side. I used to put switches and fuses on the wall voltage side but these day I just have the HV wires straight into a plug and don't even do switching... and haven't had any problems.
It's not too tricky to covert a +/- schematic to single plus supply if you realise where the circuit needs to be at half supply. What the link to this elliot thing that runs on +/-?. Is it somewhere on the ESP site? Is that what you mean by Elliot?

[sean k]

This is pretty straight forward.
But do you mean this one.

On the top one all you need to do is bias the + inputs on the 5532 to half supply so R7 and the + input of U1a would go to 4.5 volts where on the schematic they go to ground. Then you'd put some caps in to get the outputs offa ground. A cap between the point where pin 7 meets the volume control and R9 then another on the output of U1a.

U1a is set up for unity gain with the 100k resistor, R2, in its feedback path so if you want more than untiy just bring that up some. 200k would give x2 gain. As for the schematic with the headphone amp as the reverb driver... It could be made for a single supply but it'd take me ages to work that one out.

The mixing stage, on a reverb return is very similar to the setups used in delays except the rolloffs for HF and LF are just a little different.

[johnadon]

Heya, Sean, sorry for the delayed reply. The first schematic is indeed the one I was referring to. The link in my earlier post wasn't very clear  since Elliott Sound doesn't have 'elliott' in the domain name.

I hated to be a weenie and not venture an answer to the question from Uma Floresta about power supplies, but right at the time I was feeling particularly incompetent with them.

Thanks much and I appreciate your help. I've been wondering for quite awhile how one would interface circuits requiring a bipolar supply with ones that require single supplies.  I hope to play around a bit this week with my soldering iron.

(BTW, if you knew what a klutz I can be, you would understand why I want to keep the transformers away from me. I'm okay with what comes out on the fun end of a transformer, but don't trust myself on the mains end.  As an aside, I found a commercially produced 24 volt a/c wall wart in my junk box to use at the front end of the power supply for the reverb driver, so I've managed to get rid of my last self-installed transformer. True happiness.)