Spring Reverb Understanding

[tim_ado]

hey guys

i posted on here a while ago about this spring reverb project i was doing. ive found what looks to be a good start on what i want to build but ive got no idea where to start. ive got a spring tank and some electronics experience but not much knowledge.

any thoughts on this project http://gaussmarkov.net/wordpress/circuits/spring-reverb/ ?? theres schematics and diagrams on the right hand side.

thanks heaps

[davee5]

Tuuuuuubes!

Seriously, though, my take is if you're going to go through the hassle of wiring up a big ol' analog spring tank, go the full distance and copy a fender unit. There are a bunch of schematics, tweaks, and useful posts over here:

http://ampgarage.com/forum/ (Think project guitar forum, but for amps)

Another useful site for reverb stuff:

http://roymal.tripod.com/

Enjoy!

Dave

[tim_ado]

sweet im getting some sweet info off the roymal site.

just wondering is there any site that had a build of a unit kinda step by step like a tutorial?

[davee5]

I don't know of any full walk-throughs off hand, but there are a few models that get DIY'd more than others:

Fender 6G15 and Fender 5G15 stand out in this regard, and copies of the original Fender layouts can be found to supplement the schematics (which helps a TON).

These guys have kits that include the kitchen sink if you want to make your life easier (but slightly pricier). I dunno about their documentation but you can find both schematics and layouts on the site for free, presumably to supplement the box of parts you receive in the mail.

http://taweber.powweb.com/store/kits_50a.htm

I'll bet someone out there has blogged their experience in building one, but I only did research to try and add a one-tiube layout to my homebrew amp so I haven't dug in that deep.

Best of luck,

Dave

[tim_ado]

sweet

im just reading up on everything to try and absorb as much info as i can

im looking at making something that i can put in amoungs my pedals rather than in my amp. so id need to have a pre before the pedal right?

[tim_ado]

a very primitive version of this is exactly what im thinking

Edited August 11, 2010 by tim_ado

[davee5]

The old fender units were more like small reverb amps, if you will, with all the pre-amps and so forth built into what looks like a very small head unit. That wouldn't exactly make it a "pedal" per-se, but it is not a retro-fit your amp project. (That's what I'm personally doing but only because I already built the amp and I like combo units without too many externals.

That unit you've posted probably drives the springs just like the old standalone units do, but likely uses op amps instead of tubes to do so. (He notes that he uses "analog devices" op amps at that...) It's probably not "primitive" at all, and it's more than likely almost exactly the same thing as the first link you posted (i.e. the schematic here: http://www.solorb.com/elect/musiccirc/reverb2/)

As I understand it a spring reverb unit works as follows (note this is NOT an authoritative account):

- One amplifier (tube half, op amp) takes your dry signal (from an effects loop or a divider in your amp) and boosts it down the line to your tank. This typically involves a transformer taking the signal and sending the tank-ready version to the actual unit.

- A transducer (voice-coil) in the tank starts vibrating your dry signal down a set of springs at various tensions and/or lengths (i.e. decays).

- Another transducer at the other end of the springs collects/reads the bouncing, reflecting, vibrating, and otherwise spring-reverb wet version of that sound on the other side of the tank and sends a weak signal of the wet sounds up the line.

- A second amplifier boosts the weak, wet signal to a usable level and sends it through a mix pot/divider where you control wet/dry signal levels.

- Out comes that lush, surf-ready tone you've been looking for.

Using op amps vs tubes for that amplification is up to you, though the anlalog version will be much more space hungry if not the preference of tube-loving tone-o-philes. I personally lack the electrical engineering skills to convert a tube schematic into a solid-state one, so you've about maxed my knowledge on this front. I expect the schematics above are as close as you're going to get with the solid-state version. This is often why I just build from the schematics I can find or parse together, and why I actually find big, physical things like tubes easier to work with.

For your own edification, consider the simplest layout I've ever seen: the "Single Tube Reverb" you can find on the Amp garage forums. This is what I'll be dropping into my amp, because it's all I have space for, but it also keeps the schematic very very simple and you can probably see what's actually happening along the signal path for yourself. <a href="http://ampgarage.com/forum/viewtopic.php?t=569" target="_blank">http://ampgarage.com/forum/viewtopic.php?t=569</a> (<- will require registration, but there's a fount of knowledge in here, so do it anyhow.) This should be a good way to wrap your head around this stuff, and the discussion helps as well.

Keep at it!

[tim_ado]

oh no i ment that i wanted to make a primitive version of that pedal. i dont really think im up for adding all the things he has.

do you have any links reffering to op amps and tubes in regaurds to driving the springs? will i need a power supply somewhere to drive it as its going before my amp.

sorry for all the questions im just trying to gather alot of info before i attempt anything.

cheers

[tim_ado]

something like this?

http://ampgarage.com/forum/files/anderton_...b_drive_543.pdf

[davee5]

That circuit looks good to me, at least at a very casual glance by an inexpert eye.

Just dig up an op-amp equivalent (there have probably been a few model rollovers since 1976, but I'm sure you will find replacements to drop in), toss it all on a breadboard to make sure it works the way you expect, and then hard wire the exact same layout onto perf... or something like that.

Truly, without being humble, you have now pretty thoroughly exhausted whatever knowledge I can provide (especially since I've provided the references from which I learned it in the first place).

Good luck, and keep us posted on the progress!

Dave