Sustain

Georg Sørtun · From: Mandal, Agder, Norway

Being late, and only having read the last few pages on this thread, I'm wondering if on the question of sustain you have covered the issues related to "charging a resisting mass"..?

To explain as short as I can: if the points the strings are vibrating against - bridge and bar, are too heavy to vibrate with the strings immediately but eventually will - time-delay, they get charged during the time they resist. Once enough kinetic energy is stored they will resist stopping, and will thereby keep the strings vibrating too.

Now, all string instruments have mass and resistance at/around the bridge, but not very much. This means the charge is minimal and so is the released energy. Steel guitars generally have more mass pr string than most other string instruments, but it's a mixed mass - different materials, and parts and connections are optimized for mechanical functionality so there's quite a loss of charged, stored and thereby also released energy.

Imagine nearly all energy from the vibrating strings got charged into, stored in and released from one homogenous resistive mass that is tuned for the purpose. The charge-loss will be much smaller when all the non-tuned parts are kept out of the equation, won't it?
Also, the heavier the mass, the longer it will take to charge it and the longer it will take to discharge it since it has more energy stored. So, all we need is a tuned mass that the strings can charge, isn't it?

Of course, this is only theoretical since PSGs are too heavy already and it is problematic to get a large tuned mass under the bridge. But, despite these problems and all the necessary mechanical compromises, PSGs do rely on having mass at the right places for sustain. Thus, theory and actual constructions are close enough for comfort in most PSGs, giving them a reasonable amount of sustain to play on.

Now, I have this prototype construction (I've mentioned now and then in other threads) that uses a tuned mass that resists string vibration, gets charged, stores and releases energy. Not just for improved sustain, but I'll leave out most other factors here to keep it short.

I didn't want to add much weight to the PSG, so I modeled and mounted the neck as a low frequency tuning fork and let it take up all pulling-force and kinetic energy from the strings instead of spreading it around through changer, body and mechanics. Same as in the grand piano; the vibration only reaches the body through a few connection points. Loads of energy gets released into the body through these connection points, but because the storage mass has one end connected to the body and the other end to the strings, loads of energy gets reflected into the strings too. This reflected energy gets tuned - wave-shaped - to the overtone vibration in the neck, so it ends up being all positive and in sync with the string-vibration - adding considerable sustain.

As for weight: the load-bearing, laminated and rigid aluminum neck didn't add much since it replaced both the existing wood-neck and parts that were supposed to do the same "resistive mass" job around the bridge/changer. It is the free-swinging tuning fork action of the right half of the neck that holds the bridge/changer that makes it behave as if it weighed a whole lot more than what it replaced, and the thin top-plate (the Dekley's original) the neck is connected to at the left half adds to its "heavy, resistive mass" behavior.

As Donny Hinson's last post in the thread before I started to write this mentioned vibrato as a mean to add sustain, may I repeat my point about "the neck as a low frequency tuning fork". The simple fact that its basic frequency is well below that of the strings, means it starts adding vibrato once it is well charged. This "much faster than a hand" vibrato has so low swing - volume - that it can't be heard as vibrato. It just "fattens" the tones ever so slightly, but quite audibly, once it kicks in after a few hundred milliseconds low frequency charging time, making them sound stronger and clearer. It is a very important part of what makes my PSG sustain the tone - any tone up the neck - for longer.

Hope that wasn't too boring Smile

Curt Langston · Posted 6 Oct 2009 6:28 am

Well Donny broke it down pretty well. Here is an even simpler test you can do.

Simply place the bar on a single string. Then mute any ring that occurred from the placment of the bar. Next apply some vibrato without picking a note.

You will create ring and sustain from your vibrato alone!

ed packard · From: Show Low AZ

Bravo Georg...not too boring at al (to me anyway).

I would take it from the context that by mass you do not mean weight.

Let's take one mass as lead, another mass as steel of the same weight...shape to suit. Can we agree that the sonic effect would be different?

Do different materials give different preferred resonances?

Would the Qs for these be different?

Would your "tuning fork" construction have preferred vibrational "modes"?

How do you measure the "sustain/sustainment"?

Given that most would agree that the higher harmonics in the vibrating string fall off first, and the fundamental (h1) lasts longest, it would seem that any use of the term sustain/sustainment (jolly good, what?) needs to be qualified re harmonic content.

The "few hundred milliseconds" charge time would seem to indicate that some of the high harmonic have already reduced in amplitude...to what extent can they be recovered?

I am tempted to fire up my Spectrum Frequency Analyzer, and chart out the harmonic behavior of some single string behavior vs bar vibrato and time...and other such, then provide the photos/charts here or on my Photobucket site for public discussion.

As you hinted at the end of your post, it might be too "boring" for many readers.

Edp

Richard Damron · From: Gallatin, Tennessee, USA (deceased)

Ed -

I could use a dose of boredom.

Respectfully,

Richard

Brint Hannay · From: Maryland, USA

Georg, is there any chance you could post photos of the design you're describing?

Georg Sørtun · From: Mandal, Agder, Norway

Ed, let's see if I can translate some of the variables into proper English (my third language so not always easy).

Georg Sørtun · From: Mandal, Agder, Norway

Richard Damron · From: Gallatin, Tennessee, USA (deceased)

Georg -

Visited your site and was fascinated by what I read and saw. You repeatedly refer to an improvement in sustain while alluding to the lack of instrumented measurements. Can you give us a ball-park approximation of the increase in sustain that you've experienced with your design? In particular, the higher strings. Would be most interesing.

Respectfully,

Richard

Rick Collins · From: Claremont , CA USA

...hope this helps:

Subject matter - not boring. To the contrary, it's very interesting.
Brevity, to express an idea is always better.
Be concise, use as few words or characters as possible.

Very Happy

Georg Sørtun · From: Mandal, Agder, Norway

Richard, as I remember the Dekley before compared to after - the new neck went on in 92, the time I can sustain a note was approximately doubled. The change above the 15th fret was most significant of course, as the original wasn't all that great up there.

More recently; I tried to play the long passages near/at the beginning of "Blue Jade" in one go, at approx. the same low speed as B.E. played on the "New Blue Jade" YouTube video. After a few attempts getting my rusty picking right, I could sustain all the way up without adding gain with the VP, introducing vibrato or using amp-feedback, and all the way down with just a little VP gain added near the end. I found that to be quite acceptable.

Another interesting change in characteristic is that I can pick relatively lightly or quite hard and get approx. the same attack-volume - only the attack-sound changes. The neck absorbs and gets charged faster by hard picking, interacts more audible with the body, resulting in more of that delayed body-tone, warmth and sustain.

Tracy Sheehan · From: Fort Worth, Texas, USA

As i have posted before i have listened and watched Chalker play in person and over the years he played on many different brand of steels.And always had that same great Chalker tone.I was watching again an old Wilburn Bros tv show and Chalker was playing an MSA and looked as if he was above the fret board and had more sustain than most can get down low on the neck.I believe it was in his hands and he was without a doubt a master of using the volume control.
My question would be.Why do so many who see a tv show,record or what ever and ask,does any one know what kind of steel was being played?
I don't want to start WW3 but without looking i doubt many could tell the difference between an old supro lap steel and a PP Emmons.
It really means nothing but as i have also said i was born with perfect pitch (which is a curse)and i could reconize a good sounding steel (tone)when i heard it but in no way could i tell the brand of steel.depended on the players amp settings and touch.
why do so many have to ask,what kind of steel was Emmons playing on what ever?Rest my case. Smile

Georg Sørtun · From: Mandal, Agder, Norway

ed packard · From: Show Low AZ

Georg; thanks for the expanded explanation, and the website...interesting stuff.

OK, I have been driven to formalize some of the vibration/sustain (attack/dwell/decay) work that is an extension of what we did at Jim Palenscar's shop a couple of years back. It will not be brief,or short on symbols/characters, but will have lots of photos and charts.

Because it will be extensive, and probably NOT what most would prefer, I will post it as a separate thread and alert to it in this thread so those that are interested can see, and those that are not interested can avoid it. This will probably be up next week.

It will cover both the internal and external influences on "sustain" AND spectral content (= tone)...not as "words", but as experimental data and the description thereof...most in chart form direct from the instruments of measurement.

Clete Ritta · From: San Antonio, Texas

On any stringed instrument that is picked, doesn't the sustain of the note decrease as you approach the bridge?

Georg Sørtun · From: Mandal, Agder, Norway

Richard Damron · From: Gallatin, Tennessee, USA (deceased)

Georg -

You know that you have my interest thoroughly piqued by your design.

I think that I understand the reasoning behind your two-piece laminated neck. Have you given thought to carrying it one step further and constructing it with three pieces of different lengths? I ask that rather naively while attempting (erroneously so?) to parallel that with a simple broad-band electronic filter in mind. Low Q with a large bandpass. Could a suitable configuration be achieved in milling it out of a single billet of aluminum thus eliminating whatever contribution the interface between the two might have?

Bear with me while I attempt to provide some elementary background for another question. If one wanted to study the characteristics of a vibrating string in the laboratory then one might construct a jig in which the string is stretched between two supports of an apparatus with considerable mass and no unwanted resonances such that, ideally, the entire assembly contributed neither damping nor aid to the oscillations with maximum sustain being limited solely by internal damping forces and the resistance of air. In your design, are you BEGINNING to approach that idealized laboratory model with the "floating" neck/changer assembly? Is this an intended factor which accounts, to whatever degree, for the dramatic increase in sustain? In part, it would appear so. Notice that I've conveniently ignored attempting to discuss any contribution of the cabinet, etc with regards tone and sustain in my question while knowing that you have the neck assembly firmly affixed to the top of the instrument. That might be a subject better left to the likes of Ed Packard and Jim Palenscar and answered in their further investigations into the "why's" of tone and sustain in the PSG.

I would urge you to continue with the evolution of your design and, perhaps - if you can sacrifice some "pickin'" time - to provide some quantitative measurements.

Respectfully,

Richard

Donny Hinson · From: Glen Burnie, Md. U.S.A.

Georg Sørtun · From: Mandal, Agder, Norway

Richard,

I packed as much knowledge as I could of what I've gathered over the years into that design. My starting point was "the perfect laboratory model" you described, coupled in a controlled way with with a resonating body to become an instrument.
The successful tonal coupling of the neck to the existing body was the most important stage, as it would otherwise end up as just another interesting experiment.

Lack of actual data meant I had to fall back on a lot of guesswork and what I deducted from a number of simple tests performed on my Dekley over a couple of years. For instance; the tunability came about because I couldn't pre-calculate the results for a fixed design with any degree of accuracy. I also had limited control over choice of materials and production processes, as no workshops in my area understood what it was all about.
I was lucky though, as when the time came to assemble and test, it sounded and behaved well within the intended range at each stage, with zero adjustments.

I sandwiched the neck for several reasons.
1: it stabilized the neck mechanically against the bending forces of the strings/mechanics/instrument-body.
2: the epoxy won't give along such large surfaces, so the two parts can't bend much when subjected to unequal temperature changes.
3: sandwiching of unequal masses eliminates standing waves/resonances, as the two parts can never "agree" on resonance-frequencies. An old trick used to dampen hard, resonating, materials, that I've used many times in other areas.
So, yes, in a sense the neck became a "low-Q broadband filter" or rather "two high-Q filters at different frequencies in series" = zero output (ideally). What's left is "dead mass", where the weight/length ratio coupled with the resonance frequencies in the top-plate, makes it a low-pass filter.

Milling the neck out of one piece would have compromised it both mechanically and tonally. Probably possible to configure a pattern that would work/hold reasonably well, but nothing beats sandwiching IMO.

Could probably have reduced the weight by cutting out large chunks along the neck, "tunnelling" in between the two parts before gluing, but would inevitably have reduced the neck's "deadness". I would have had to correct/compensate by precisely calculate the hollow shapes and filling them with dampening material. Not much to gain, IMO.

I'll release sound-bites when I have put all the necessary pieces to record on together, or before that if I'm satisfied with someone else in the area's recording equipment/solutions/result. I'm extremely picky when it comes to sound, so I rather just pick for myself and family/friends until I can make and release proper recordings.

Richard Damron · From: Gallatin, Tennessee, USA (deceased)

Georg -

Thanks for the near-instantaneous reply. Please keep us informed as to the status of your experiments and any developments of significance that may occur.

Respectfully,

Richard

Georg Sørtun · From: Mandal, Agder, Norway

Some loose notes (for those still interested)...

Compared my Dekley S10 with a pretty new Carter D10, last Friday, at a fellow steeler's place. My friend stroke my unconnected Dekley's strings lightly when we had it up on its feet, and commented: "Gosh, it's vibrating through the floor. My Carter doesn't do that at all."
Well, I checked, and his Carter did resonate through to the floor, but with the actual string-tone frequency and not by much and only when driven fairly hard. My Dekley resonated through with high-energy sub-frequencies at fairly constant levels whether it was picked relatively lightly or very hard - picking-intensity doesn't matter all that much.

Now, we didn't get together to compare steels, but to practice (my friend is a relative beginner with a little over a year behind his Carter, and I'm a rusty old-timer). So, the rest is pretty non-scientific...

The difference in tone-range, -characteristics and playable sustain became quite clear when our steels were connected to identical amps - NV-112s, set up in accordance with each player's preference.
The Carter was dialed in for fairly increased lows, slightly lowered mids around 800 Hz, and increased treble and presence.
The Dekley was set at neutral lows, 11 o'clock at 800 Hz, and neutral treble and presence.
Both steels were run through impedance matching units pre VP, and there were a moderately adjusted, barely audible, digital delay in the chain on the Carter.

- The Carter sounded and sustained just fine, but couldn't in any way hold/sustain the tone like the Dekley anywhere on the neck. As I've mentioned earlier; my Dekley kicks in and adds volume to the tone half a second after the attack, resulting in a smooth rise in tone-strength - "blooming" - that increases both perceived and actual sustain.
- The Carter didn't produce all that much volume in the lows - despite the increased eq'ing of lows. The Dekley OTOH produced clean and evenly distributed mids and lows, quite a bit "more massive" but not much stronger than the Carter in the lows.
- The Carter produced nice, ringing, highs, with no particular peaks, dips or other characteristics that couldn't be explained by the increased treble/presence eq'ing on the amp, and sustained well enough for comfort fairly high up up the neck.
The Dekley produced what I again will call "more massive" highs, with a more moderate but lasting ring - no eq'ing, and had quite a bit more sustain to milk than the Carter up in "Hughey land" - not very hard to make my Dekley "howl" between 15th and 30th fret although I usually don't play up there very much.

Overall, I'd conclude that my heavily modded Dekley can hold the pure tone nearly twice as long as my friend's new Carter - when played by me, and that my Dekley tends to "growl" a little and gain volume when called for, something that particular Carter didn't show any tendency to. It was an interesting comparison of two good steels, but, as mentioned, not very thorough and/or scientific - we were just having fun playing our steels for hours Smile

On another note: I've gone through a few scattered notes scribbled down while I was modifying my Dekley all those years ago. One is particularly interesting, as I tested the efficiency of the mechanical frequency divider I make use of to create those ultra-low resonances my Dekley exhibits. It's all simple physics, so thought I might as well share.

At one point I tested out tuning of the Dekley's "tone lip" - a free-vibrating part of the top-plate that the changer was mounted on originally. When fine-tuned as "a rattler", that tone-lip acted as a pretty efficient frequency divider and increased the body-tone and sustain quite a bit. Problem was; the tone-lip wasn't really tunable from the builder's hand, and having the changer bolted onto a flexible top-plate didn't help much on body-drop.
So, that part of the original design created more problems than advantages IMO, but it did lead me onto the track that ended with the present design - which behaves as a multi-step "rattler", but without the rattling noise and other problems.

Anyone who knows how "a rattler" works, and a bit about charging and discharging resistant masses, can build amplifying mechanical frequency dividers and use them constructively to make resonating instrument bodies become self-tuning resonant masses that increase "blooming" and sustain - perfect for PSGs.

From what I have learned through others; Emmons P/Ps can be nicely tuned as "rattlers", which may count for some of the increased sustain many players seem to get out of them. I have no personal experience with Emmons PSGs.

Of course; if "rattlers" are out of tune or the masses and their resistance are unbalanced, the result is just noise and decreased tone and sustain - quite the opposite of what most of us want in a PSG. Just thought I should mention it Wink

ed packard · From: Show Low AZ

The first of the "sustain/sustainment" Photos and charts are up in another thread = "Them good vibrations" Talk about "boring"!

Dick Sexton · From: Greenville, Ohio

Thank you Ed, I'm patiently waiting for the second installment.

Clete Ritta · From: San Antonio, Texas

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