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Discussion in 'Glowing Bottle Tube Amp Forum' started by Xingshen71, Sep 8, 2017.
I, too, am baffled.
Xingshen71s's post got me thinking so I pulled the grille on my Conqueror 5 and sure enough, there are a couple of micro cracks in the baffle.
One at the top of the baffle and one at the bottom. Not good. Any suggestions to slow these down? Or is it time to get out the saw and router and replace the baffle?
Ime with new builders of amps and cabs, there seems to be two levels. One of those consists of people who have put in the time observing and/or working with older known quantities and therefor have some basis for understanding what should and should not be done. The other level consists of those who have enough knowledge to put something together but not enough knowledge to know what should and should not be done in that building process.
Anytime I see something that has been done differently from what has worked in the past, I want to see something that has substance and quality in those differences. Ex: The old Fenders, Gibsons. Marshalls, etc used wood screws to affix the back panels. Good enough....except for some companies such as Matchless, Tone King and a few others. They use machine bolts with threaded inserts for that work. Those 'holes 'will never wear out and will never need to be redoweled, will they? That is a change that is an improvement, imho. Nailing a baffleboard is not an improvement, imho.
Using solid wood for a baffleboard impresses some people because they read 'solid wood' and think that is preferable to plywood. Solid wood is better than plywood for a guitar soundboard---usually, but void-free plywood is better for an amplifier baffle board.....always......ime.
Re: Badspikes baffle board crack.. BAdspikes, if that were mine and I wanted to try to save it I would fill the void with some high grade wood putty and then span the crack with some bowties to hold the thing together...because it is going to want to keep growing. I haven't watched this, but here is a video on the subject.
Wally and Silverface, I think you both make some excellent points regarding the construction issues with this little thing.
I'll be honest, I had not given the solid wood baffle construction much thought when I purchased the amp. Sure the glossy purpleheart looked kinda cool. but I just left the grill cover on after like the first day. Electronically, this thing has performed without issue and met all my expectations and requirements. Basic Champ clone with point to point wiring and a 12" speaker. Include the attenuator and its a fun little amp. I hesitate to call it " boutique " since I got it for less than $300 shipped.
So, talked with my buddy and void free birch, glued and screwed is what we came up with as well. I'll be dropping it off this evening and he thinks he can have it ready by the weekend. I will post pics of how it turns out. I'll probably stain the front purple again since that was what the original was. But maybe not. Have to get some test pieces and see what works best.
Not sure if the dark spot inside the crack is some sort of inclusion in the wood or an attempt at a repair.
Sorry to see your having the same issues. I bet if you look where the brad nails are shot thru the back you'll find your cracks are in those areas. Not sure humidity was the major problem with these but more like the build process and materials. Like I said above, I'll post pics of what I end up with.
Again, thanks to all for the comments and suggestions. I have some new knowledge on something most people do not even think about until there is a problem. Hopefully this thread will help others with similar issues.
Dude, stop it! I'm tired of cleaning coffee outta my keyboard!
Remove the speaker, work a good amount of carpenter's glue into the crack, clamp it for 4-5 days and then hope it holds.
I also suspect humidity problem.
The crack in that purple heart in the Zingshen's amp is far too wide to even think about repairing, imho. When wood separates in this manner, there is a point at which one has to fill the crack with more wood IF one wants to try to salvage the piece. I would not even bother with this piece of wood. Pull it out, set it aside....it will continue to dry and crack in other spots, imho.
The crack in BAdspikes board might be dealt with with some sort of filler and those bowties. Anything else would be like spitting in the wind, imho.
Had the baffle and frame pieces out on Saturday. Gave the amp and pieces to my buddy doing the work. Unfortunately, I won't be able to do anything with it until next week.
Figure the baffle and pieces will be sacrificed to appease the Glowing Bottle Gods!
Someone might want that piece of purple heart for some sort of woodwork...after it cures.
Similar splines are what I've used forever in acoustic instrument repairs and restoration. Cracks in an acoustic guitar top caused by pickguard shrinkage (very common in older Martins) are repaired - after removing the 'guard - with hide glue and the top carefully clamped to close the crack. Then one or two *very* thin spruce splines about 3/8" square and 1mm t thick are glued with opposing grain.
They hold amazingly well. Side and back cracks are done the same way, but with the appropriate wood.
They have no noticeable affect on the sound. I've used up to 25 on a 1910's ukulele an dit sounded tremendous.
Splines don't need to be the shape seen in the video - simple rectangles work just fine. *If* they were to be used to repair a solid-wood baffle I'd make them around 1/8" thick.
But I wouldn't fix it. Chances are it will fail again.
AS I understand it in the repair of guitar tops. splines are cuts of woods that are made from the same material as the top and cut in the same orientation as the grain of the top....that is, the spline will have grain in line with the grain of the top. IF the crack is large enough to demand, it, the crack should be glued with a backer inside the top..or the side or the back....and is not visible on the outside. The backer is made of the same wood as what is being repaired and is glued 'cross-grained'. After that is set, then the crack is 'opened' up in such a manner as to be made ready for the spline to be glued into that crack. There is a special tool for opening that crack up....smooth sides and controlled width and depth. Using this method, the repair can become almost invisible...depending on how much work is put into the cosmetic touch.
Thanks Wally! good info and video! I think the baffle is save-able for the time being but ultimately I think it'll have to go. I'll hand it over to my Dad who has a little clock building wood shop. It'll keep him entertained for awhile.
No, they must go the opposite direction. IF the splines - which are very thin - have grain matching the crack direction they invariable crack right in line with the top (or back, or sides). The point of a spline is to bridge, strengthen and prevent the crack from spreading.
When made thin enough and roughly the size I mentioned they have no noticeable tone effect despite the cross-grain placement. They are placed the same way in general woodworking. I've done hundreds on my own and in various tech shops over the years - virtually nobody in the instrument world installs them with the grain and when old ones are found like that - often cracked - they are always replaced.
Splines are used so much there are some luthier supply shops that sell strips of various woods - you can cut off a few dozen and have 'em ready to go. I buy most now ( usually a dozen 6" strips at a time of spruce, mahogany, rosewood and some koa...mainly for ukes) as they're time consuming to make.
Here's a short woodworking discussion on the subject:
And here's a guitar repair example (although I'd never make them that thick!). Some like diamond shapes, but they don't perform any better - and usually add mass.
Siilverface, with all due respect, we are talking about two different things. IN the musical instrument world, a spline is a piece of wood that matches the spot to be repaired and is laid in the same direction of the grain of the original wood. This spline is not a reinforcement but rather is a piece that fills the gap that was created when the original wood...usually the soundboard....was left unrepaired for so long that the gap is too large and won't come back to a 'mating' situation. In such a situation...reread my post #31...the crack is glued up with a backer INSIDE the body that is the reinforcement for the repair. THAT piece of wood is the same material as the original wood and is applied cross-grain for the strength.
This is not new technology, and there is a tool built for the job of preparing that repaired gap to accept the spline, which is a piece of wood that again matches the wood that is being repaired and has its grain oriented in the same direction. This repair technique can allow a luthier to repair say a top with a big, wide crack in such a way that many people would not see the repair. IF one places a reinforcing piece cross-grained on the outside of the instrument, one has visible repairs that would look strange to a luthier.
Again....with all due respect, a luthier who came across an instrument with the reinforcement pieces glued on the outside would be like you seeing a hack job on a guitar amp. In instruments...big or small... into which one cannot get one's hands, this entails using a technique that pulls the backing wood up to the inside of the top with string. I have tools worked up using tuning machines to do that pulling and holding. Yes, this entails putting small holes in the wood through which that string passes. After the backer/s is/are installed and the cracks are stable, then one does the cosmetic work...whether that entails simply touching up the outside or it entails inserting the splines.
I have been doing this type of work much longer than I have been working on amps.....and I am fairly good at it. I did numerous such repairs on a couple of stand up basses that were worth many thousands each. The fellow for whom I did these repairs has had such work done by numerous folks.....and he was much impressed by my results. You could not even find the small holes that I had to put into the tops, backs, and sides. The other repairs that had been done over time were amateurish by comparisons....but he probably paid more money to them than I charged him for my work. I work by the clock. I guess I am too fast????
Sorry Wally, but that's not correct - I've been doing them for 40+ years. Most of my work is acoustic instrument restoration. "Splines" - sometimes called "cleats" go across the grain. "Splints" are placed into cracks to fill open areas that either can't be closed or where wood is missing.
Seriously, I do this every day - I have two acoustic guitars, a dulcimer and 6 ukes in right now for crack repair and other work.
From the article I linked:
"A Simple Repair consisting of working some glue into the crack and cleating it won’t hold up in the long run. Instead, I’ll inlay a thin piece of spruce, or “splint” into the crack and reinforce the repair with some cleats."
Note "splints" - used when the crack won't stay closed and needs fill wood, and "cleats" (aka "splines") across the grain. It think the similar spelling may be causing the confusion.
Silverface, I will grant you that I have misused the word spline.....when I meant splint. Thanksf for that correction. This is the process I am describing....using the word backer where one can use 'cleat'...for the reinforcement piece inside the instrument. You are using the word 'spline' for that.
Spline for me is this....
Silverface, in this post, you describe a 'spline' as a piece of wood worked into the repair on the outside of the instrument. Am I misunderstanding you? The cleat or backer, which you are calling a spline, should be inside the instrument and not visible form the outside.
At any rate.....we do agree that his piece of purpleheart is a lost cause.
Don Teeter calls the piece of wood that is inline with the grain of the wood in the repair, and which we can agree is a splint, a 'crack filler piece'. LOL......
A "spline" on a musical instrument is a small wood piece placed perpendicular to a crack - internally - to prevent the crack from opening again. normally several are used.
A "splint" is placed *in* the grain asa patch to fill 1) an open area where wood is missing, or 2) to fill a cracked area where the crack sides cannot be pulled together.
I didn't talk about wood pieces used to fill chipped/broken areas that are not fully open. If wood is missing on any surface - but not open to the inside - the common term used by everyone I know is "patch". There may be a different term used in a book somewhere. I haven't looked at the Teeter book in years - many construction and repair techniques he used have been superseded by new methods and materials.
The only term for those among luthiers and repair persons I know is "patch", with "splint" reserved for through-surface repairs - and "spline" or "cleat" for cross-grain reinforcing pieces glued on the inside only.
It's usually the same in general woodworking, hence the use of "splines" for reinforcement if the cabinet crack was to be glued.
So, got the amp back with the repaired cleats and baffle.
Cleats are solid Birch glued with Titebond II and screwed to cabinet. There is also clear silicon along the perimeter of the cleats to help eliminate any possible rattles or noise. Very secure!
The speaker baffle is Baltic Birch void free ply at 1/2" thick. It has been pre-drilled and test fit to the cleats. I will use some clear silicon as well as the screws for the final install after I put a finish on it. Going to look at stains tomorrow. I test fit the speaker and its good to go. Need to drill the holes for mounting the speaker.
I think it turned out really good and definitely stronger than the original.
Just as a side note, Panama Guitars never responded to my email. I think this repair is going to be better in the long run anyway.
Not the best pics, but you get the idea!
I will post pics of the final install after I finish the baffle.