Spring Reverb Question

GuitarlCarl · Post by **GuitarlCarl** » 13 Jul 2012, 23:05

Hey I'm not an amp guy... I hotrod guitars and do odd wiring jobs for the local shop on the side. I have poked around a little and made minor repairs to a few amps, only obvious stuff, faulty jacks etc. Took some electronics, op amps and such, in college, long ago, no tube stuff, but I can read a schematic. Anyway, spring reverbs interest me, and I've seen nothing on them here. Sooo...

Can anyone give me a simple explanation of just whats going on in a reverb tank? Maybe something about building a stand alone unit. I have a few spring tanks donated to me and I swapped out the small one in my Musicman65, for a long tank from a Hammond organ, sounds different not necessarily better, hence my interest.

Dr Tony Balls · Post by **Dr Tony Balls** » 14 Jul 2012, 01:21

As far as tube builds, a stand-alone reverb is an excellent first build, so if you're thinking about that I would certainly encourage you.

As far as mechanics, the whole thing is setup like and amp, but instead of a speaker at the output there's a transducer connected to a spring. When you play, the transducer vibrates the spring, and another transducer at the end of the spring picks up that signal and mixes it back into your output signal. I like to think of it like a pulse going down a spring that is picked up later, creating an ultra short delay. Of course that pulse is also gonna bounce back and forth for a while adding extra delays. Not sure if that makes sense, but thats how I think of it.

ppluis0 · Post by **ppluis0** » 14 Jul 2012, 01:35

Hi Carl,

Everything you ever wanted to know about reverbs, and never dared to ask, you will find in this link: http://www.accutronicsreverb.com/

Just click the tab "How reverb works" , and enjoy you reading

Cheers,
Jose

phatt · Post by **phatt** » 14 Jul 2012, 11:25

This is about as good as it gets without valves;
http://sound.westhost.com/project34.htm

at least Build Fig 4 or similar.

Or this might work but you will need a transformer and note the polarity issue. (diodes reversed)
http://www.drtube.com/guitamp.htm#Gibson

Find *GA-3RV Reverb III* schematic on that page.

If you want dripping wet over the top reverb then my effort can be found here;

https://www.freestompboxes.org/viewtopic ... rb#p185025

But ESP circuit is your best bet if you are not sure.
Be warned a lot of spring rev circuits on the net are not so good and some are just a waste of time.

Cheers, Phil.

GuitarlCarl · Post by **GuitarlCarl** » 14 Jul 2012, 18:48

You guys are awesome, thanks brothers, I was thinkin' about tryin a stand alone unit... Carl

Dr Tony Balls · Post by **Dr Tony Balls** » 14 Jul 2012, 19:58

I built one that still need a faceplate...

ppluis0 · Post by **ppluis0** » 15 Jul 2012, 04:29

Hi Tony,

I think that you can employ a pair of pieces of plexiglass (similar as some H&K amps), and let everybody seen the tubes glow inside.

Congratulations for the enclosure of your reverb. It's very pleasant to me when I do some wood work from time to time, and is also pleasant to see a job well done by others.

BTW... can you post the schematic of this unit ?

Cheers,
Jose

Dr Tony Balls · Post by **Dr Tony Balls** » 15 Jul 2012, 18:58

yep. its the same as this one:

CHEEZOR · Post by **CHEEZOR** » 16 Jul 2012, 16:41

phatt wrote:Be warned a lot of spring rev circuits on the net are not so good and some are just a waste of time.
Cheers, Phil.

I just wanted to mention that I own 1 of these: http://www.guyatone.com/Fr3Kv.php and it is probably my favorite pieces of music gear I have ever owned/heard. It also has more control over the reverb sound than most other reverb units. The unit warms up your whole sound. You can actually turn the reverb volume all the way down and it acts like a nice warm tube preamp. I think it is based on the old Fender reverb units, but Im not sure. Its loaned out to a friend at the moment, but I could get it back in a couple weeks and take some gut shots if anyone was interested.

I also have some quick recordings that I did a long time ago that I could upload so you could get some sound samples.

CHEEZOR · Post by **CHEEZOR** » 16 Jul 2012, 21:39

Alright, I don't care if you want to hear them or not. Here are some clips anyways. lol

These are all super quick recordings that I did a long time ago just to either try out some equipment or remember a short riff. Very little if any post processing has been done and I messed up a few times in the recordings.

These were never really meant for anyone besides me, but you'll get an idea what it sounds like.

Esso28 · Post by **Esso28** » 18 Jul 2012, 20:01

How about my stand alone Reverb Tank

I put all the parts into the Tank.

https://www.freestompboxes.org/viewtopic ... 10&t=18503

GuitarlCarl · Post by **GuitarlCarl** » 19 Jul 2012, 02:19

yer bits in the tank as a stand alone is cool. I have a small three springer that I may do the same type of thing with using the PhAbb Maxiverb schematic... Thanx Phil!

I'd like to try a tube drive one too, but it never seems to me like the schematics are all there... I look at a tube schematic and the look at a tube circuit and there's a lot more going on then just what's in the schematic. And since I have no training in tubes, ya know "I'm not an amp tech..." first will be the Maxiverb.

I really appreciate all the links too, thanks guys for pointing a tube newb in the right direction...

phatt · Post by **phatt** » 19 Jul 2012, 13:42

Good on you Carl,
I'll try and get a zipped up short sound clip , might give you inspiration

.

Do read all you can on ESP site as it will all help to get your head around it.
If you can check the DC resistance of the input coil and output coil and write them up as that will give us an idea of any potential issues you might run into.

@ Cheezor, that Guyatone unit sounds great and BTW I was referring to sites that post schematics N

ot factory gear.
My Maxiverb is on the bright side tone wise more like early Fender Amp units as I found a lot of circuits I tested where too flat in the bandwidth and those lack sparkle.
It depends on your need I guess?
Cheers Phil.

CHEEZOR · Post by **CHEEZOR** » 19 Jul 2012, 18:18

phatt wrote:Good on you Carl,
I'll try and get a zipped up short sound clip , might give you inspiration .

Do read all you can on ESP site as it will all help to get your head around it.
If you can check the DC resistance of the input coil and output coil and write them up as that will give us an idea of any potential issues you might run into.

@ Cheezor, that Guyatone unit sounds great and BTW I was referring to sites that post schematics N ot factory gear.
My Maxiverb is on the bright side tone wise more like early Fender Amp units as I found a lot of circuits I tested where too flat in the bandwidth and those lack sparkle.
It depends on your need I guess?
Cheers Phil.

I would love to hear some sound samples!

I'll have to post some gut shots of the Guyatone when I get it back. It should be a simple one to trace out for anyone familiar with Fender reverb units or tube amp circuitry in general. I don't have much experience there...

phatt · Post by **phatt** » 20 Jul 2012, 06:55

As promised,,Demo of my PhAbb Maxiverb.

Recording process;
Direct Record (no mic) > normalize > convert to low quality MP3.
So wipe off some treble above 4kHz to replicate the sound through a Guitar speaker.

I hit the foot switch in a couple of places so you can hear the dry sound to make comparisons.
The dwell and Depth are set at 1 O'clock which is done to show the ability of the effect but for normal playing I only use it on 1~2.
At max it gets pretty crazy swimming which would rarely be used but nice to know it's there for some crazy surfin fun.

The reason I built this is simply because most Amps on-board spring reverbs are average at best and some are just worthless.

Even some Valve rigs today have barely working reverbs and they do not come close to the old units of years past.

The key to reverb (for guitar at least) is the freq response of the reverb unit/circuit itself. Most opamp powered units around are current drive and this seems to flatten out the response but I found you need a lot of voltage swing to get the *Driver end to push hard enough* to replicate the old Valve units. Opamps are incredible things but are limited when BIG swings are needed.

The Tank itself does play a large part in the final result but if you are using Accutronic type tanks with the right transducers then you will
be saving a lot of stuffing around. If you are lucky you may find some odd ball tank that works fine but some are really bad and resonate badly when driven hard like mine.

Remember the tank is purly mechanical and once the signal is converted to vibration on the spring the sonic result is totally dependent on the quality of the spring and the way it is designed.
Another subtle point that most miss is that more rows of springs will be of little use,,

You don't need many rows of springs for a good reverb. Most of them have the transducer/coil at one side of the iron core and the
spring closest to the transducer passes 80% of the sound so more than 2 rows of springs is overkill and wasting money.
With the top off it's easy to prove this by gently muting the springs one by one while passing a signal.

Note on digital reverbs;
Most can produce *longer reverb time* but very little effort is placed on frequency response.
Sure they claim 20/20 bandwidth but therein lies the eFup,, way too much bandwidth is most of the problem with modern digi gear.
That said the digi Belton brick setup has impressed me and might be easier to implement.
But hard to beat a good analog Spring Reverb

Anyway you folks can judge for yourselves if it's worth the extra effort,,

The Maxiverb unit is deathly quite and has given me trouble free use for close to 10 years now.

Have fun, Phil.