Resonator guitar experiments

[Steverino]

Hello, this is my first post here Sorry that it is a long one...

Recently I began playing lap steel guitar, after an overseas friend bought an old Richenbacher on ebay and had it delivered to my house. This has proven to be a gateway drug into Weissenborns and resonator guitars as well. I recently attended the NAMM show and sampled quite a few instruments, including several resonators. I decided to get my feet wet and order one of those cheapo $69 Chinese resonator guitars on eBay. I did not expect it to be much of a guitar, but I wanted to have an unimportant instrument to experiment with and learn from.

When the guitar arrived it looked impressive but sounded awful; very quiet and barely a trace of the typical resonator twang. It is the spider cone Dobro style instrument. First thing I noticed is that several of the spider arms were contacting the underside of the perforated cover. Upon disassembly I found that the center screw had been so overtightened that the center section of the cone had buckled upward. The cone seemed rather thick (about .014") and its outer suspension felt tremendously stiff. The spider was a crudely sand cast, heavy unit; only five of its eight arms seemed to be contacting the cone. The perimeter of the cone was only touching the rim intermittently, as there were lumps of finish all around. The wooden bridge was much narrower then the spider groove, and sat there loosely and hunched over.

So, after reading a couple of online tutorials, the work began. I scraped and leveled the rim (there is no sound chamber in this beauty, the resonator rim is attached to the top); flattened and ground the spider to contact the cone evenly; added veneer to the side of the bridge and sanded it for a tight fit to the spider. I reassembled the guitar with some new Martin Bluegrass strings, leaving the resonator cover off for the moment. The sound was greatly improved, quite a bit louder and more Dobro-like. Only problem was that the bottom three strings didn't keep up with the rest in terms of volume. It seemed likely that the cone's suspension stiffness was preventing it from moving adequately at the lower frequencies.

Today I took it apart again and began filing material off the peaks of the cone's outer supension; two on top and one underneath. I kept at it with a large file, carefully, round and round for an hour or so. Every so often I would feel the suspension and it became progressively more flexible as I continued to file. When it seemed that it might perforate with much more filing I reassembled the guitar, tuned it up and gave it a try. Holy cow, what a difference! The lower strings came on strong; all but the lowest now equal an old Kay archtop guitar (a real boomer) in volume. The high strings became louder as well, though they didn't change as much as the lower strings did. Overall it is much better balanced... and loud!

Next step is to tackle the clunky spider; I'll try filing off some of its excess mass. It seems logical that string energy expended in moving the spider mass is not available for producing sound. I may try filing the cone a bit more, to try and bring up the 6th string a little more. Even if it doesn't improve further, this is already one fine sounding $69 guitar.

From my day job as a loudspeaker designer/builder, some questions come to mind. I wonder to what extent the cone vibrates as a piston, and to what degree it breaks up into resonant modes as it is excited by the strings over the broad range of frequencies it produces? Since the volume of all notes came up when the outer suspension ("compliance" in speaker talk) was made more flexible, I suspect that the cone maintains piston motion for a fairly broad range of frequencies.

I would be interested in hearing from others who have done this type of work, techniques employed, results obtained, etc. I would also caution against disassembling and modifying valuable and functioning instruments. Without a skilled luthier's knowledge such harebrained experiments as mine should be contained to instruments of the $69 sort.

[MossmanGP77]

Steverino,
You need to post this on:
http://www.reso-nation.org/
They're a great bunch of folks and there are some highly respected reso builders on there too. Your day job experience relates well with resonator guitars and I'm sure that the reso-nation would like your thoughts.
(tried to post this the other day but couldn't - seems the forum was down)

[DaveG]

Hi, Steverino, and welcome to AGF. I read your post with interest since I recently aquired an inexpensive resonator as well, although mine is a buscuit bridge rather than a spider bridge. It sounded ok, but was a little dull sounding and lacked sustain. The only change I've made so far is to replace the stock biscuit and bridge with a new one from Beard. The stock one consisted of a wimpy, skinny little bridge glued to a massive biscuit. I believe this combination absorbed most of the vibration from the strings before they ever reached the cone. The Beard biscuit and bridge is just the opposite, with a stiff, ebony capped bridge and a smaller biscuit. I also raised the action slighly to get a better break angle over the bridge. The results are impressive with much improved volume, tone and sustain. It sound really good now, even with the stock cone. It sounds like what you are doing has the same effect, more stiffness and less mass. I'm interested to hear how the rest of your experiments go.

[Freeman]

For spider setups get a copy of Paul Beards dvd - it is basically what he does to turn an import into a Goldtone. I'll also suggest replacing a stamped cone with a spun one - I run a Quarterman in my spider and just put a new NRP in my biscuit (I also replaced the maple biscuit with a carbon fiber, but I'm convinced most of the change was from the cone). I did clips before and after on the Duolian and will post them one of these days.

It might also be worthwhile to read Bob Brozman's book on Nationals - it is mostly the history and lore surrounding Nats but there are some good tips about spiders also (I thought it was interesting that John Dopreya was quoted as saying they tried almost every material for bridges including brass, and came back to maple as the best sounding).

While I don't think string make as much difference on a reso as they do on an acoustic, one of my little favs is an unwound third - that string gets uses a lot in slide work and many players like a plain one.

There are a few good forums dedicated to resos, here is one I like

http://www.guitarseminars.com/cgi-bi...Forum&number=1

[Lewguitar]

Hey Steverino...I'm wondering if I just bought a Taylor off of you on ebay? Regardless, welcome to the forum.

I have a couple of nice resonators and a few old lap steels including a couple of mid 30's bakelite Rickys and a Silver Hawaiian.

But what I'm curious about is about is the online tutorials you made reference to. What were they?

Thanks! Lew

[Steverino]

Thanks to all for your kind responses.

MossmannGP77, thanks for letting me know about ResoNation; I copied my post there. Looks like a great forum.

DaveG, happy to hear of the improvements to your guitar. There must be thousands of these things out there performing way below par. In the case of mine, the factory workers were simply throwing parts together with no attention paid to results (not that I'm complaining for $69). I think it was mostly a case of excess cone suspension stiffness that was killing the tone, as filing the cone did the most good. The cone measures .014" thick, whereas it is mentioned in Bob Brozman's book that the Dopyeras were spinning cones from .006"-.008" foil.

Freeman, I have Mr. Brozman's masterpiece of a book; it helped to hook me into the reso world. Thanks for your link... I'll check it out.

Lewguitar, that wasn't me with the Taylor. If I had one of those I probably wouldn't let it escape! I found numerous references to resonator setup on the web; the two below are probably the best. Congrats on the beautiful Rickys. Trying a friend's Model 59 recently got me interested in slide playing, and in studying the history of the Los Angeles based guitar manufacturers.

http://www.robanderlik.com/reso_set-up.htm

http://www.stewmac.com/freeinfo/i-4006/index.html

[Freeman]

Beard setup dvd

One of the most compelling parts of this is when Beard holds up a stamped cone and taps it with his finger - it makes a kind of dull thud. He does the same with a spun cone and it rings like a bell.

Beard is selling the new style NRP biscuit cones but is often out of them. You can order directly from National ResoPhonic. I haven't tried to buy a spider cone but I would assume that since they are now making spider bridge guitars that you can get a cone (check diameters).

[Alejo]

hey!

perhaps this movie clarifys how the cone (can) vibrate:http://iwk.mdw.ac.at/am/?page_id=1500&len=gb

nice regards
alejo

[Bikewer]

I've got a cheap (well, 300 bucks) "Rogue" resonator, the "Bell-Brass" model.

It sounds really good to me; loud, resonant, twangy... Just what I wanted. However, in looking the thing over it's obvious that one area they cheaped-out was the bisquit.
It's very poorly finished and the saddle is set into it rather crudely. If I ever decide to try fiddling with the thing I think that's where I'd start.

[tdq]

You can get cones and biscuits here, too
http://www.nationalguitar.com/catalog/resonators-cones
Bikewer, for $10 a biscuit upgrade might be worth the trouble!