Building a DIY Spring Reverb: Part I

[@ronfreeman1691]

The blend pot has to be grounded on one of your grounding lugs on the pot, otherwise it's dead when you go to center on blend. So ground your input and output together and wire to ground lug on blend. Either top right or lower left.

[@musicalmiscellany]

That's probably what I did wrong. No worries though. If you watch Part II, you'll see I came up with a different solution. I'll remember that if I try again though.

[@c1ph3rpunk]

Back in the mid 80’s I picked up an obviously homemade rack mount spring reverb. Used it for many years, loved it, but ended up selling it with that rack to help fund a minivan when my ex was pregnant with my eldest. Was the best sounding reverb I’ve ever had, that was 1985 and it looked beat up then, had to be made in the 70’s. Been searching for that tone since, which is what landed me here.

[@musicalmiscellany]

Sometimes those makeshift effects are some of the best. Thanks for checking out the vid and for sharing your story. It sounds like you had a one of a kind piece of gear there.

[@goodun2974]

A while ago I watched a KZbin video where somebody had built a recording studio style plate reverb in miniature with a metal shelving unit!

[@davidglynnguitars8119]

Just a thought. If you used a stereo amplifier and ran the dry signal through the left and the right. Then use one side for the reverb and the other for the dry, you could control each side with separate potentiometers to balance the levels and send that to the single output. That might eliminate the blend pot issue. I use small 5VDC amplifiers to make practice amps that run off USB power banks.

[@musicalmiscellany]

That's a great suggestion. Thank you.

[@tysonbrown9531]

Thanks for this video! I’ve been wanting to build something along the lines of this for a while! On a different note, it’s always awesome to see fellow DFW Citizens YouTubing!

[@musicalmiscellany]

Thanks for checking it out man. Make sure you check out Part II when I fixed the blend control. Teaser... Part III is coming soon. And yes... I'm trying to rep more local businesses as you see here with the ReVolt t-shirt. Thanks for checking it out man.

[@DEEP_PRACTICE]

Great video, spring reverb is just so cool!

[@musicalmiscellany]

Thanks for checking it out. Be sure to check out Part II and III. I'm really happy with the final product.

[@RevvyTone]

Glad you're doing this. Last winter I bought a bunch of parts including transducers to make one very similar...and forgot about it. Over the weekend I actually found the transducers. I've had the same issue with trying to wire those blend posts on other effects... so I'm hoping you've solved it in part 2.

[@musicalmiscellany]

Thanks for checking it out. Ironically, Part II just posted this morning. Check it out.

[@alanc6752]

Pretty rad i think i will give one a go. Great video.

[@musicalmiscellany]

Thanks. I'm pretty impressed by how it came out... just a random idea but it worked.

[@MarcoPono]

Thank you for making this video!

[@musicalmiscellany]

Thanks for checking it out. I hope it's helpful.

[@stevesstrings5243]

Very interesting project!

[@musicalmiscellany]

Thanks Steve. It was a crazy idea but it worked.

[@jfrankcarr]

Interesting project. I tried something similar in a CBG build. I built the "spring reverb" into the box hooked up to a piezo separate from the main pickup. When I wanted the built-in reverb I had a mini-toggle to activate it. It was muddy though. Maybe I'll revisit it.

[@musicalmiscellany]

Yeah. That's exactly what I was trying to avoid. A straight reverb spring loses a lot of definition and ends up sounding really muddled. I was hoping to blend the original signal back in to keep things sounding musical. Stay tuned for Part II cuz I've got some ideas. Thanks for check ing it out.

[@goodun2974]

​@@musicalmiscellany, You need to bandwidth-limit the drive signal to the reverb tank, to filter out the bass and low midrange so that it doesn't reach the drive transducer. In a Fender tube amp with reverb, this would take place because of the low-microfarad-value capacitor that feeds signal from the driver tube into the reverb transducer, as well as some lpw frequency roll off caused by the small output transformer used to match the high impedance of the driver tube with the 8 ohm. Your solid state driver's circuit, however, is designed for audio fidelity and has high frequency bandwidth.

[@musicalmiscellany]

@@goodun2974 Thanks for that feedback. It makes sense. However, any time you add 100% wet reverb signal you're going to lose some definition. You need to mix the clean signal back in.

[@goodun2974]

@@musicalmiscellany , not surprisingly, 100% wet signal is rarely desirable; and yes, a "mix resistor" arrangement is necessary so that the two signals can be blended and level-adjusted without totally killing the signal. The reason I mentioned bandwith limiting the input to the reverb transducer is so that you won't waste energy shaking up the spring with low bass notes, which causes intermodulation distortion to take place in the spring itself as well as when the wet and dry signals are blended. BTW, I looked at your part 2 schematic and it appears to me that the 100k pot for the dry signal will introduce a relative low resistance, and variable loading, to the guitar's pickups; 100k is much lower than the potential owner values typically found in the guitar which are usually 250 to 500k or even higher, which affects frequency response and tone from the guitar. Also, you haven't wired the pot like a proper voltage divider and so the impedance load that the guitar sees will vary greatly as you adjust that control. You may find it interesting to Know that multi instrumentalist David Lindley, who passed away last year, used to play a highly modified mutant bouzouki that he built from a bouzouki neck grafted on to the body of a Vox "teardrop" Bill Wyman bass, with piezo *earthquake sensors* inside the body as additional pickups that could be blended in with the magnetic pickup. There are videos of him on KZbin with his band ElRayo-X where you can see him play that thing!

[@rock2blues59]

Looks like a fun project. Can't wait to see part two. Think I'll try it with a Booker's Bourbon box cause I know by the time I empty the bottle to get to the box. I will be happy with any outcome of the project. lol Really great video.

[@musicalmiscellany]

What? Did someone say Bookers??? LOL. A Bookers box would work perfectly BTW. Thanks for checking it out.

[@jonr4651]

If you're looking for surface exciter/transducers Dayton Audio has the best selection I have found.

[@musicalmiscellany]

@@jonr4651 thanks for that comment. I know they can be difficult to find. I appreciate it.

[@ronfreeman1691]

The pot more than likely is not defective. On the blend pot try soldering a small wire from top right lug to bottom left lug. Then solder a small piece of wire from top left lug to bottom right lug.Ground either top left to bottom right or top right to bottom left onto pot. Then ground that to output ground lug. Use center lugs for each input and ground each. It should work right then.

[@musicalmiscellany]

Thanks for checking out the video. I may need to try a blend pot again. I obviously did something wrong in this project.

[@ronfreeman1691]

@@musicalmiscellany ok. One thing I did leave out though. Some companies build pots different. If what I told you doesn't work, switch ground wire on pot to opposite connection. In other words ground opposite wires to pot. I've been building guitars and basses using blend on active/passive circuits in my preamps for years and have found this out the hard way! Have a good day.

[@Live.At.The.Garage]

Would also be pretty damn cool to wire up a snare throw or something to have variable tension on the spring. Cool project man!

[@musicalmiscellany]

Cool idea. Thanks for checking it out.

[@shawnlennon1947]

you are the best! thank you!!

[@musicalmiscellany]

Thanks for checking it out. I always hope these videos are helpful to someone else.

[@JohnBassarcticsoundstudios]

Cool I'm from Oak Cliff also. Nice Shirt.

[@musicalmiscellany]

Always good to find a local. Thanks for checking out the vid.

[@rolandocaraballo]

I believe you need to disconnect the ground that coming from the dry side

[@musicalmiscellany]

That could be. I'm not sure but I found a workaround. Thanks for checking out the vid.

[@bobyk87]

It might happen that the reverb preamp inverts the phase, so when summing with the dry it cancells it out, you may try an extra inverter stage (single transistor or opamp), on the dry or the reverb signal. You should also see overall opamp theory.

[@musicalmiscellany]

@@bobyk87 thanks for the suggestion and also for watching. I appreciate it

[@bobyk87]

​@@musicalmiscellany i literally burned my vox combo (china), with speaker and the reverb can; but the chassi is waiting to become a head... that reverb was ok.

[@Cyphera59]

Fun project! just a thought using the 250K ohm pot, when you reach the top of the the taper profile the full 250 k in affect shunts the signal? If you have an oscilloscope, you could verify that. What we need in Texas is some rain, I'm down the road here in Clyde it was 110 yesterday. Looking forward to part two.

[@musicalmiscellany]

Yeah, I think it's just a bad pairing for the circuit. I'm gonna fix that though. I should get part II up soon. Thanks for checking it out.

[@pierpa_76pierpaolo]

1:44 Could you tell me how this capsule works, I had bought them but was very disappointed. Help.

[@musicalmiscellany]

I have no experience with those mic capsules. I opted for going the piezo route on this project and have not purchased any capsules to date. Thanks for watching the video.

[@pierpa_76pierpaolo]

@@musicalmiscellany Ah ok. I am following your idea to be able to build myself a surface contact microphone and this reverb might come in handy (but I was thinking of a metal cylindrical shape ... ). I 'd tried piezos too but was not very satisfied with the poor result. But I had to apply 5V. I will try again.

[@rubenestradaglz.4735]

You can use a regular pot and ground both signals to the middle and the positives on the sides and it should work as you intended but I'm not entirely sure

[@musicalmiscellany]

So if you put an input to each side and ground in the center, where does the output go?

[@LunarCascader]

Could the silence at the center of the blend pot be caused by phase cancelation? Anyway, thanks for the cool video. I recently came into a box of 24 little weighing scales that have nice, delicate springs in them, and this was the first thing I checked out to get an idea of how to make a reverb from some of them. Instead of a transducer, Ima try different materials to make a membrane overtop of some laptop speakers with huge magnets, which also have a bunch of.

[@musicalmiscellany]

@@LunarCascader good luck with your project. I hope it comes out great I’m still a little bit baffled by why that dual gang pot didn’t work. Some folks have chimed in below to explain their ideas. In any case, it works great with the two pot set up. Thanks for checking out the video.

[@davidcoates4852]

I know, this is 2 years old but you might get a stronger pickup signal if you mount the piezo similar to the transducer, supported around the circumference with a hook glued to the middle 🤔🔧👍

[@musicalmiscellany]

Thanks for checking out the video. I actually thought of that during the prototyping but I was afraid it would ruin the piezo. If you've ever looked closely at one, the center disc is made of paper thin ceramic. Just a slight crack in the ceramic and it can stop working (or at least not work as intended). I decided to go the safe route. I'm wondering if a larger mount that somehow covered the entire ceramic disc might provide enough surface area to stop it from cracking. It would be a fun thing to try. Thanks again.

[@davidcoates4852]

@musicalmiscellany Thanks for the reply. I love improvised stuff. I have never made a spring reverb or even used one (disclaimer), but I have messed about with piezos. The ceramic is only on one side, could you not put the glue on the other side, the plain brass side? I think the brass would be pretty strong if supported all the way around its cercumference. Besides piezos are cheap or even free. Worth a try 😀🔧👍

[@smellymala3103]

Aw man I know what I’m going to do with the eq hardware in that broken acoustic that Jimmy dropped off yesterday

[@musicalmiscellany]

I'm glad this vid gave you some inspiration. Thanks for checking it out.

[@fearlessfreddy1000]

Hi Kale, I can hardly wait 'til the next installment of Dr. Frankinverb & the Magic Box. When you get the idea perfected will it fit inside a CBG? Blessings from the Emerald City.

[@musicalmiscellany]

Hmmm... you probably could fit this whole thing inside a CBG. To tell you the truth... I didn't think of that. It would be a lot of wiring but I think it would work.

[@suedelacy]

Can we get an IR?! This is awesome!

[@musicalmiscellany]

Thanks for checking it out. I'm not sure what an IR is though.

[@paradiselost9946]

piezos... you need extremely high input impedances to get a decent signal... they form an RC high pass filter. a standard preamp wont cut it. need 10Meg or better for a nice full range signal... blend is better done with two devices feeding a common load resistor. 12ax7 type tubes are ideal, twin triodes... not everyone does tubes though. whatever. can use regular transistors or fets. this stage only has to be low gain, an impedance buffer... can feed an opamp or other preamplifer from there. the real issue is the way the spring is driven. better to use small DC motors. most commercial reverb units, ie, the "accutronic", amongst others, use TORSION. they TWIST the spring, rather than tension/longitude waves, or transverse/up and down waves... if you tear down the transducers, you find its far more like a "synchronous AC motor" than a speaker coil. diametrically polarised magnets held between the two poles of an electromagnetic. a submersible pond pump or stepper also works... means they are a lot less prone to external noises.. vibrations... theres a bit, but far less than you get with the two more "conventional" modes of propagation. meaning the amplifier stage can have way more gain as theres far less chance of howling feedback loops. it also means the springs can have far less tension on them. i only clicked as the thumbnail looked like it was using a motor drive... nope. just a piezo operating in tension... sigh.

[@musicalmiscellany]

@@paradiselost9946 Thanks for the detailed explanation. It makes sense.

[@tanz5229]

what was the signal path for the reverb? (guitar to reverb to amp to cab) just as an example

[@musicalmiscellany]

That's more or less correct. The signal went from the guitar into the reverb and then to a small combo amp. Make sure to check out Parts II and III because I made some improvements.

[@tanz5229]

@@musicalmiscellany ok thank you will definitely check those out

[@iBorsch]

Hello. I have a Harley Benton GA5 guitar amp into which I would like to build in a spring reverb. Which I'll take from an old Laney PL50 Reverb Can you tell me where to attach it according to the diagram? I want to build it into the body and mix in the sound of reverb.

[@musicalmiscellany]

Thanks for checking out the video but I wouldn't be able to tell you how to do that. Adding an internal reverb to an amp is not an easy task. It requires and analysis of the circuit and you'd have to splice into the circuit board (if there's even a place to do that). I understand the want to add a spring reverb to a small tube amp. I had a similar situation with my Vox AC4. I ended up getting a small reverb pedal and some velcro and just velcro'd it to the back of the amp. Then I used a pedal patch cable to plug the pedal into the amp's input and I always plugged the guitar into the pedal's input. To be honest, after a while, I forgot the reverb wasn't built-in.

[@goodun2974]

​@@musicalmiscellany , Kley De Jong made a KZbin video about a one-tube add-on spring reverb circuit that can be added to virtually any tube amp. The circuit itself is pretty simple but tapping into the power-supplies and existing tubes in the amp would require a good knowledge of tube circuits.

[@musicalmiscellany]

@@goodun2974 I'll check out that vid. Thanks for the suggestion.

[@id.unknown1283]

You should reach out to Richard of Brand Noise as he makes musical gadgets (here in Dallas) and he might have some tips on getting the blend pot to work or something else that might be helpful.

[@musicalmiscellany]

Holy moly. Are you psychic? I literally just talked to him. I should have a review of one of his products up next week. That's uncanny. In any case... thanks for checking it out and yes... Richard is a super cool guy.

[@id.unknown1283]

@@musicalmiscellany look forward to seeing the review I have a couple of the instruments he makes, they are super fun.

[@musicalmiscellany]

@@id.unknown1283 I think they seem like a really cool company and good folks. I hope I can help to promote them. Video coming soon... stay tuned.

[@mirkoskender4418]

Are pot A250K ore B250K???

[@musicalmiscellany]

I think it was a B250. I can't remember for sure. However, I ended up going to a different setup in Part II of this series.

[@E-BikingAdventures]

Instead of buying those expensive components, you could have used an LM386 driving an actual little half watt speaker with most of the cone removed and attaching the spring to it.

[@musicalmiscellany]

There's obviously a lot of different ways you could accomplish this. All of my DIY videos are made to be templates and you modify as you see fit. Thanks for checking it out.

[@goodun2974]

​@@musicalmiscellany, another piezo driver could possibly be used as the drive transducer, since larger piezos are used as tweeters. The high internal capacitance of a piezo would provide bandwidth limiting and filter out most of the bass and low midrange frequencies so that they never reach the springs.

[@musicalmiscellany]

@@goodun2974 That's a great idea.

[@goodun2974]

@@musicalmiscellany , The Silvertone amps that were built for Sears by Danelectro in the 60's had a cheesy one-spring reverb using what may be *Rochelle salt* crystals as a piezo type transducer for both the spring driver and recovery pickup. These reverb tanks fail and drop-in replacements aren't available (Fender style tanks won't work in Silvertone amps without major modification to the circuitry); and they never sounded much like a surfy Fender reverb anyway (very lo-fi and distorted, which some people like for effect). I've been wondering if those little piezo discs could work as substitute transducers to rebuild and hopefully improve the reverb in those Silvertone amps. BTW, Rochelle Salt crystals were used in the earliest crystal mics, sometimes found in old Astatic, Turner and even Shure mics. Blues Harmonica players love em, but original crystal mics rarely work at this point because the crystals absorb moisture and disintegrate. If you shake an old vintage crystal mike, It'll often sound like a salt shaker because of the pieces of crystal rattling around inside. Rochelle salt crystals can actually be grown to a very large size and some people grow them strictly for ornaments because of their beauty. I've seen videos on this done being in somebody's kitchen!

[@goodun2974]

@@musicalmiscellany , have you ever watched any videos from the Museum of Everything Else channel, aka This Museum Is Not Obsolete? The British guy named Sam who runs the channel did a video a few years ago of a vintage reverb device he found that used a 6x9 speaker to mechanically excite a quad set of springs mounted above the speaker cone. The wet signal was mechanically generated by the springs vibrating in sympathy with the music or tones coming from the speaker, had didn't have any drive or recovery transducers. Even sweeping test tones through it sounded very interesting. It might be on his original Look Mum No Computer channel.