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Securing Loose Bracing/Removing Cross-Bracing on CS249 Nylon O

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arumako
Posted 2019-07-23 4:14 AM (#549467)
Subject: Securing Loose Bracing/Removing Cross-Bracing on CS249 Nylon O



Joined:
October 2012
Posts: 888

Location: Yokohama, Japan

Hello OFC! Man, it's only been a few months, but it feels like it's been a long long time. I hope everyone is doing well. I must say, Ovation presence in Japanese music stores has sagged dramatically over the past 6-months. None of the major stores in my area are carrying Os anymore. Haven't seen a single one on show room floors in the past 6-months! On the sales floor, there seems to be a lot of confusion as to continuing (or not) USA production. Kinda sad, but there is a healthy used O and A market out here, and my collection is certainly being utilized fully. Been really enjoying my nylon string Elite style CS249 Celebrity Deluxe that I repaired here:

http://ovationfanclub.com/megabbs/forums/thread-view.asp?tid=48161&posts=40&start=1

She developed some buzzing recently, and repair and upgrade of this O became my first summer project. Every Elite style guitar repair begins with a massive appreciation of Os unique manhole cover. Pop it open and voila! Easy access to everything you need to get too!

manhole cover access

After feeling around a bit, there were clearly a few braces that were slightly coming loose. Always wondered what removing the lower cross-brace would do to this fun-to-play nylon stringer. For those of you who've seen the thread above, you might remember this nylon stringer had braces worthy of a steel string 12-stringer - just look at the hefty bracings on this baby...

Hefty bracing

It's kind of like an A-Brace, Quintad, and K-3 all combined in one. Previously dubbed the "overkill" "resonance killer" bracing pattern, actually, I think the lower cross-bracing was installed to stabilize the resonance inside the bowl to prevent lower-end feedback that is so common in nylon/electrics. The guitar sounds great through a PA or amp. Acoustically? She's got a sweet but completely restrained voice. So why not take the shackles off and liberate her voice!

Grabbed my trusty iron, miniature spatula heated her up and slowly removed the lower lateral brace. It took about two hours of slow slow work, but finally came loose - used a sharp chisel to clean things up. Look at the size of this thing!

cross bracing

This cross-brace is actually trapezoidal. The cross-section reveals a quarter inch width at the top and a five-sixteenth inch width at the base. The sandpaper stick in the middle is a cool double sided 600 grit stick that really makes finishing in tight spots a cinch.

After removing the cross-brace, the buzzing became amplified. A quick but careful slide of my miniature spatula along the base of the lateral-braces (with guitar tuned to concert pitch) revealed several compromised areas. The spatula finds its way under the lateral-braces like this;

spatula under brace

After checking both sides of each lateral-brace and the upper cross-brace, I lightly marked each area in need of adhesives with a pencil. This time I used regular Tite-bond. Put some on some scrap wood for easy access with my spatula. Then carefully applied the glue to the compromised area. This is repeated and the glue is lightly pushed under the bracing to ensure holding after drying.

glue and spatula  apply glue

After applying the adhesive to all relevant areas, the strings are loosened and the guitar left to dry with the manhole cover off. Clamps are not necessary!

brace removed

Now, 24-hours later, put everything back together; and whadya know! This thing sounds amazing! It's still not as resonant as my all wood classical guitars, but her voice is definitely liberated! The lack of cross-bracing is not stressing the table at all. And the Lyrachord bowl gives her a really unique and punchy nylon voice like no other guitar I own. Cool! Now, I just need to run her through my PA and amp to see if there are any unmanageable feedback problems! Woohoo!



Edited by arumako 2019-07-23 4:18 AM
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Love O Fair
Posted 2019-07-23 6:49 PM (#549472 - in reply to #549467)
Subject: Re: Securing Loose Bracing/Removing Cross-Bracing on CS249 Nylon O



Joined:
February 2016
Posts: 1189

Location: What week?
Hi, Ken! Good to know you are doing well, and its also nice to see some action on the BFLG forum. That second photo looks more like the view through a scuttle hatch at the inner hull of an 18th century sailing ship than a guitar! That's some really heavy stuff in there. As the story unfolded I was tongue-in-cheek with you on removal of the lateral brace. I hope its absence stands the test of time, but great also to know that your skilled sense of ingenuity was able to feel its way to a solution for the buzz. Always a treat to see your work!
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arumako
Posted 2019-07-24 12:52 PM (#549488 - in reply to #549467)
Subject: Re: Securing Loose Bracing/Removing Cross-Bracing on CS249 Nylon O



Joined:
October 2012
Posts: 888

Location: Yokohama, Japan
Thanks Al! Really nice to have the time to be able to just sit and share a wee bit. The cross brace removal is working out really nicely with no feedback issues at all. Hope to share a video in a few days. Pretty sure the top will not be affected negatively. Wish I had a 1613 or a 1773 for a comparison. I get the feeling that this liberated Celebrity might compare rather favorably to her US made cousins! Yes!
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DetlefMichel
Posted 2019-07-27 8:25 AM (#549508 - in reply to #549467)
Subject: Re: Securing Loose Bracing/Removing Cross-Bracing on CS249 Nylon O



Joined:
May 2011
Posts: 607

Location: Muenster/Germany
Ha! Finally someone had the guts to try what should becomea real improvement. That was the best you could do for this poor overbraced guitar. The braces left now are still more than sufficient for a nylonstring, seemingly 5-6 times the size of Torres braces.. Maybe the layered Celebrity top needs a little more suspension than a solid spruce top.
Did you ever try THOMASTIK SUPERLONA CF 127 strings? These strings look like flatwound steelstrings for a Jazz guitar but are made for Classical guitars with normal tension. They will bring stunning results on a (still very stiff) top like this. I use them for my Rissmann guitar which has a very light bracing (you know) but a spruce top like a floor tile. I will try to bring my small Lumix camera back to work soon and show you more.
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Love O Fair
Posted 2019-07-28 3:13 AM (#549517 - in reply to #549467)
Subject: Re: Securing Loose Bracing/Removing Cross-Bracing on CS249 Nylon O



Joined:
February 2016
Posts: 1189

Location: What week?
@Detlef - >>>THOMASTIK SUPERLONA CF 127<<<

it seems this is the second time I went off to search info on these strings per your recommendation, though I have yet to try a set myself. I, too, have a "floor tile" top on my old (1988, I think) Celebrity CC13 that may benefit from these strings. Problem is, there is a tricky bridge issue that requires me to use ball end strings on that particular guitar (typically Martin 260s), and I assume the CF127s are traditional tie end. I have never converted tie ends to ball ends by tying a bead onto them, but I have heard others say they have. Would you still recommend the CF127s under those conditions, or possibly the CR127 round wound? It would be nice to wake this guitar up a bit.
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arumako
Posted 2019-07-31 9:58 AM (#549531 - in reply to #549508)
Subject: Re: Securing Loose Bracing/Removing Cross-Bracing on CS249 Nylon O



Joined:
October 2012
Posts: 888

Location: Yokohama, Japan

DetlefMichel - 2019-07-26 10:25 PM
Maybe the layered Celebrity top needs a little more suspension than a solid spruce top.
Did you ever try THOMASTIK SUPERLONA CF 127 strings?

Thanks for the nice comment DetlefMichel! The CS249 has a Sycamore Maple (0.5mm veneer)/ Spruce (1mm)/ Sycamore Maple (0.5mm veneer) laminated top. Sycamore Maple is no where near as hard as, say Canadian Rock Maple, but it is way harder (about twice as hard as) Spruce according to the on-line Wood Database, so it should not need more suspension than a solid Spruce top. In reality it should need less; so, as you say, even without the cross-brace, this nylon guitar is "over-braced". Interestingly, the top is only 2mm thin with the poly finish adding another one millimeter; so, there is more resonance to be had if the poly was stripped and the top was French Polished (definitely not going to do that)!

And actually, I've never tried Thomastik strings of any kind! The Superlona CF127 sounds really interesting. I checked out their website, but that set is not available in a high tension formula. My CS249 definitely needs high tension strings to resonate the stiff table!

Well, the results of this "Cross Brace Removal" experiment have been an overwhelming success. Prior to removal, I made some audio recordings with the guitar in OEM condition. Fortunately, I kept a record of the equipment used and took pictures of my recording setup. A vintage Sony F-460 mic setup in tandem with a Shure 588SDX like so (not exactly Hifi, LOL)...

Sony & Shure

The mics were connected to my Macbook and recorded via Garageband with "Normalization" turned off. The signal reached the Macbook through my 2nd Gen Focusrite Scarlet 2i2 which was set-up like this...

2i2

Pre-Cross Brace Removal and Post Cross Brace Removal "acoustic only" recordings were made using the exact same setup and here's what I found. First of all, I measured the Pre and Post Cross Brace removal sustain of each open string: The results were impressive:

Sustain

Both the Pre/Post Cross Bracing Removal audio signals were exported into an MP3 file, and imported into Sonar Producer. Like most DAWs, Sonar's GUI transforms the audio signal into a picture to help users visualize the shape of the audio signal. It's nothing like a vibrometer or a frequency meter, but it does give a general idea about the dynamic character of an audio signal. Here's what the Pre/Post audio signature looks like (combined into one file for easy comparison)...

signal

It's pretty easy to see that the removal of the cross-brace has dramatically increased the dynamic range of this guitar. In reality, there is always the human element that makes data of this kind rather unreliable (you know, like playing harder during the Post Cross Brace Removal recordings to get a favorable outcome) however, even if I worked in a 30% "margin of error", the results would still be stunning!

Finally, I produced a simple audio recording with the Pre-Cross Brace removal CS249 in the left channel and the Post Cross Brace removal CS249 in the right channel like so;

https://soundcloud.com/user-253026784/cross-brace-arpeggio

A sampling of the audio seems to verify that the "voice" of the guitar has not changed all that much, but the dynamics of the instrument seems to have improved dramatically (maybe not so obvious in the audio recording, but very obvious when one plays the instrument). The overall resonance of the guitar is drastically improved, and projection is much much stronger.

I've been wanting to experiment with Cross-Brace Removal on my Celebrity guitars for a while, so this has been really fun and rewarding. Learned a lot in the process too. Keep in mind that doing this will absolutely invalidate the warranty on your guitar; so, be really careful if you ever decide to dig into a project like this! Thanks for letting me share OFC! Gonna keep playing my Os all summer long! It's hot and humid in Japan so stay cool everybody!



Edited by arumako 2019-07-31 10:23 AM
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Love O Fair
Posted 2019-07-31 11:47 AM (#549533 - in reply to #549467)
Subject: Re: Securing Loose Bracing/Removing Cross-Bracing on CS249 Nylon O



Joined:
February 2016
Posts: 1189

Location: What week?
Awesome report, Ken! I, too, was considering the human error/favoritism side while reading along, but when you factored in as much as a 30% margin, it is clear to me by looking at the numbers and the waveform samples that you struck some gold with your work here. Even if setting all tech data aside and going only with purely experienced human ears, I'm guessing that if Glen Campbell had been at your side through the whole experiment and played the same samples, we would have seen his pearly white smile when playing the post-brace-removal licks :-)
Congratulations on a successful endeavor!
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arumako
Posted 2019-08-02 2:11 AM (#549543 - in reply to #549533)
Subject: Re: Securing Loose Bracing/Removing Cross-Bracing on CS249 Nylon O



Joined:
October 2012
Posts: 888

Location: Yokohama, Japan

Love O Fair - 2019-07-31 1:47 AM

I'm guessing that if Glen Campbell had been at your side through the whole experiment and played the same samples, we would have seen his pearly white smile when playing the post-brace-removal licks :-)
Congratulations on a successful endeavor!

Thanks Al, but you go too far with your generosity! I'd imagine that's the kind of collaboration Mr. Kaman and the folks at the Mother Ship enjoyed with Glen. Speaking of Glen Campbell, here's a cool video of him with his famed 1624 (I think? The headstock looks a bit suspect to me though...)! Amazing instrument!

And here's a very cool thread from the Glen Campbell forums about his 1624 and his switch to the blue Adamas cutaway nylon. If you click the link to the Adamas XSC-8 story, you'll recognize two veteran OFC members too.

http://www.glencampbellforums.com/viewtopic.php?t=115

Really cool history! While I do love my reworked 'Celebrity's, the CS249 is a "Super Celebrity" only by name in my hands. Had the "real" celebrity (Glen Campbell, that is) "been at my side while I did this experiment", I get the feeling he'd be saying, "Hey kid, stop wastin' your time and get yourself a USA Ovation!" LOL!

Whoa! The YouTube video is working! How cool is that?



Edited by arumako 2019-08-02 2:17 AM
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Love O Fair
Posted 2019-08-02 10:30 PM (#549546 - in reply to #549467)
Subject: Re: Securing Loose Bracing/Removing Cross-Bracing on CS249 Nylon O



Joined:
February 2016
Posts: 1189

Location: What week?
@Arumako - >>>"Hey kid, stop wastin' your time and get yourself a USA Ovation!"<<<

Now THAT'S funny! Good one. Good links and info, too. Thanks for posting!
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