Spring reverb

[martin manning]

Small update on this rack-mount SS spring reverb project... Picked up a bipolar power supply kit, https://www.vellemanstore.com/en/vellem ... supply-kit which is perfect for the Tape Op reverb. It's the same circuit shown in the TI LM137/LM337 data sheet with a few protection diodes added. The 34V CT flat-pack transformer already in hand provides the AC, and it doesn't need a large heat sink if the output voltage is toward the high end (reduced AC input voltage helps too). With little U-shaped heat sinks it seems to be running quite cool when powering the reverb, and it's quiet too. This is a handy thing to have around for breadboarding, so I bought a couple ;^)

[TUBEDUDE]

I hate to waste a power tube on reverb. When i built reverb circuits, i found a 12au7 driven push pull into a center tapped tranny much better than the paralleled stages. I used a hammond 125. Overkill for sure but it was here. The reverb was more powerful and livelier.

Tanks are inductive loads, and as such their impedance rises with frequency. Driving the tank with a solid state current source will nullify the rising impedance.

I no longer design reverb circuits, as with one tube i can have a fully buffered effects loop, and insert any effect including the three reverb/delay devices i own that do a better job than springs.

[martin manning]

Dude! Spring reverb is a thing! Lots of people like it!

[Phil_S]

I don't mean to sidetrack this terrific thread too much, but maybe we can also entertain a discussion about the tanks? I mean, it takes two -- the tank and the circuit.

A while back (several years) what I gathered from various posts was that the quality of the new tanks (two major sources: Accutronics and Mod) were inferior to the old tanks. Is this still the case or have folks just got over it? Also, there are old Gibbs tanks available on eBay from time to time at reasonable prices, however, does anyone know how to figure out what model numbers those are? I mean, why would you buy an old Gibbs if you couldn't identify it?

[TUBEDUDE]

Dude! Spring reverb is a thing! Lots of people like it!

I know, back in the '80's i builtt a reverb using 4 type 9 tanks. I used 2 short delay and 2 medium delay tanks in parallel. I drove each pair differentially, hoping to eliminate the "sproing" from driving too hard or from mechanical shock. I also expected a broadened spectrum with better dynamics and lower noise. It was huge and a big time suck but the results were.....underwhelming. It sounded like a good verb, but not much better than one type 9 tank current sourced.

The one thing i found that made reverb springs pop was to send the preamped spring output to the second input on the phase inverter. If you are a reverb junkie you will love this. Though it does require disconnecting the feedback, if your amp is so encumbered.

[dbeasley]

How much current handing can a tank itself handle?

I love me some spring, but I ended up getting a Strymon Flint and never looked back

There is also a great digital option - the Spin FV-1. Has a cool GUI you can use to create and download reverb patches that sound great. The tricky part is integrating it into a design.

To me though, the king of spring is the cap-coupled Ampeg V4 reverb circuit. Truly 3D sounding, and very clean. Almost like a studio effect.

Sent from my moto g(6) using Tapatalk

[TUBEDUDE]

Build your Own Clone has a reverb kit using the FV-1. Sounds great and is in a mini pedal case, about 1"x2".

[martin manning]

Progress pic on the rack-mount spring reverb. Old-school layout process; no CAD on this one...

[roberto]

I haven’t measured total current draw, but the data sheet says power amp idles at 70mA from +/-25V.

Thanks for your links Martin, great reading. So based on that you could drive it with up to 140 mA, and it means you must have maximum 180 Ohm on the usable spectrum (let's say from 0,15 to 6 kHz) due to voltage limitations. Isn't it?

[martin manning]

I haven't tried to compute how much drive current there is with +/-18V supply, and I don't see much information on limits in the tank data either. There is some discussion on that subject here: https://www.tubesandmore.com/tech-corne ... d-compared, but basically it says drive the input as hard as possible without saturating the transducer's core.

Here's another progress photo. It would have been finished today but for the IEC inlet. This chassis has an aluminum front panel, but everything else is mild steel. My plan is to use a jeweler's saw to finish that cut-out, but unfortunately I'm out of blades.

Circuit ground is floating at this point, not sure if I'll have to tie it to the chassis. It's sounding very good, and it does subtle to gnarly surf 'verb. I'm also quite pleased with the sound of the 4BB3C1B Mod tank.

[tubeswell]

... I love me some spring, but I ended up getting a Strymon Flint and never looked back ...

I also have a Flint as a permanent fixture on my pedalboard, but while is is one of the better digital reverbs out there, it just can't keep up with my 6G15 tank. The sounds are just so splishy.

[M Fowler]

Very cool project Martin and hope it goes together well for you.

Mark

[Mark]

Martin, keep us in the loop how the reverb sounds in comparison to other circuits.

[martin manning]

Update after a year in use. Still working fine, and sounding good. Circuit ground was left floating with no issues. I can recommend this Hamptone board and parts kit for anyone wanting a SS spring reverb. The Velleman bipolar power supply is fine too, and cheap! Here's a pic of the finished unit with retro-looking chicken heads and Dymo panel labels.