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Post subject: VV Structural question.
Posted: Sat Jul 06, 2019 3:00 pm
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Hi all. Sorry about all the VV/speaker questions......I'm a data/info freak. :lol:

1. Is there any known reason why the holes in the OEM baffle plate are squared off at the top and bottom?

Why'd they do that and can I just cut a complete circle? Does anyone reckon it is for a bit of extra structural strength at the top and bottom for those particular speaker screw holes? Surely with 8 screws or so sharing the weight of the speaker, it is not necessary?

2. Why is the hole in the baffle 3/4" smaller than the speaker cone diameter? The diameter of the speaker from inside to inside of the gasket thingy is a hair under 14" while actual OEM hole is 13&1/4".

So........ 8)

3. Can I just cut the hole exactly the dimensions of the speaker cone......14"?

I'm also wondering how much the cone moves outwards and if it can kiss the wood.

BTW......this is not the actual new baffle I am using...it's a tester and also so I can use the cut hole as a template on the real piece (especially if I decide to offset the speaker slightly) .....and I will try to get my jigsaw skills better too. Because it was not to be the actual piece.....I went a bit fast hence the jagged circle and also drifted to the outside of the pencil mark in places. ( I realize this is not finish carpentry though...LOL)

Also......I did not want to peel the grille cloth from the OEM baffle so I could not use it as a template to draw the speaker hole. Instead I clamped that piece of the new birch plywood to the OEM baffle and used the sharp tip of a compass to pass through the tiny weave in the grille cloth and make a bunch of dimples or 'points' on the wood..... and then I joined them freehand with a pencil. (No damage to the grille cloth) I also found the center of the wood and scribed a circle using a 6&5/8" radius. I cut a small rectangular piece of luan ply with a nail at one end for the hole center and a hole on the other end for a pencil at 6&5/8".......rotating it to scribe the circle. I was almost dead on with the freehand.
Image

Thanks all for accommodating me!!

I know I can just do it and f()ck all the questions. I also realize that small amount of 'unnecessary' coverage of the cone will not affect the tone in the slightest. But if it is a manufacturing deal to cut costs and save time somehow.....I'd rather do it right. For example.....my 1960 Marshall 4X12 cab had circular holes.

My gut tells me I can cut a full circle and either offset or spin the speaker by eye to miss the transformer etc etc and not make a huge magilla out of it and it will be 100% fine. But nothing wrong with knowing all the in's and out's either.

Sidebar. At the last gig I did, the soundman placed the mic centered at the top of the speaker hole and I swear at least half of the SM57 grille would have been somewhat over the wood section of the baffle, where it is squared off. This would definitely mess with the signal he was getting but neither he or I knew that the hole was not a full circle. I wondered why he wanted the mic so far to the edge of the cone in the first place, but did not question him since I already had sorta kinda annoyed him (not really, but he had a bit of a 'tude going and things were delicate) and I was trying to calm the waters so he did a great job for me. Which he did.....even complimenting me on being so self sufficient with my tone and having all my various clean/crunch/lead volumes dialed so he did not have to ride my fader all the time...... as well as complimenting me for having a good stage level. :roll: He mentioned how so many guitar players that he did sound for at the club, were always too loud, especially during solo's. Really? :mrgreen: I would never have guessed. :P :lol:

That said.....I normally like to mic 12" speakers towards the middle of the cone or perhaps a bit more more towards center. I don't know where these 15" speakers sound best when mic'd or why he did that.


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Post subject: Re: VV Structural question.
Posted: Sat Jul 06, 2019 4:29 pm
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To help stop the grille cloth getting baggy over the speaker....a little extra wood area to glue the cloth to?


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Post subject: Re: VV Structural question.
Posted: Sat Jul 06, 2019 6:23 pm
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The baffle is unsupported along the top edge, so the extra wood helps stiffen/strengthen it.

They may do the bottom the same just so it's identical/reversible. Fits in either way, so they don't have to worry about a hungover assembly line worker putting one in with the weaker side at the top.

It's probably strong enough if you make it a full circle. But there's some increased chance of it getting kicked in and cracking along the top. I'd go ahead and copy the "flats" when you make the new baffle.

Cone won't hit the overhanging baffle. Speaker openings vary -- don't know why, but for the same size speaker different companies make the openings slightly different.

There can be "lensing" effects from the baffle and cab lips. Some open-back cabs are more directional/beamier than others. I've observed/heard those effects, but haven't figured out exactly what factors influence it.

To get the best comparison between the JBL vs the stock Eminence, ideally you should make the new baffle identical to the stock one (except for the location of the mounting holes). Might not really matter, but then you know everything you hear is solely due to the speaker change.


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Post subject: Re: VV Structural question.
Posted: Sat Jul 06, 2019 6:30 pm
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Fumbly wrote:
To help stop the grille cloth getting baggy over the speaker....a little extra wood area to glue the cloth to?


Shouldn't be any glue. Traditionally, Fender baffles have thin strips of wood around the edge of the baffle face, so the cloth floats off the surface of the baffle. The cloth is wrapped over and stapled from the back.

Some companies do wrap directly onto the baffle, and I suppose Fender might do that on some models. But no glue.
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That's another possible consideration about a larger full circle speaker cutout. You'll be surprised by how tight you have to stretch the cloth when applying it. Might possibly bow in the thin areas at the top and bottom.


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Post subject: Re: VV Structural question.
Posted: Sat Jul 06, 2019 6:39 pm
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As for mic positioning, that's kind of an arcane art that I'm not experienced in.

Soundman might have had good reasons, or crazy reasons, or just stuck it there without giving it much thought.


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Post subject: Re: VV Structural question.
Posted: Sat Jul 06, 2019 9:52 pm
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Hey there Strayedstrater.....thanks for that. I have done all my marking, checking and triple checking....drilled the pilot holes for the speaker and baffle mounts, made the recesses for the T-nuts etc.....and I was about to cut out the speaker hole......full circumference. I decided to come in and see if there were any replies first in case I needed to make the lips.

You make some good points. I'll go with what you recommend.

strayedstrater wrote:
As for mic positioning, that's kind of an arcane art that I'm not experienced in.

Soundman might have had good reasons, or crazy reasons, or just stuck it there without giving it much thought.


This guy actually does a good job. I've seen other bands he mixed and the sound was awesome.....and every time I have video'd our band at that club, we sounded friggen great. Well......as far as our mix anyway. :D So as to the mic placement, I don't know and at the time I just decided to trust he would get me a good sound.

What I have found over the many years (and I know y'all know this, but I'm just sayin....).......is that it is not good to antagonize the sound mixer even in the slightest. It is actually a good idea to offer to get them a beer or whatever to get them a bit more invested. In the past it was more likely to have been an offering of white-ever :shock: :mrgreen: :twisted: ........but those days are long over in my world.

But still...he's doing a job for you and probably gets paid shite.......so it's always nice to 'tip' your sound and stage lighting persons. Definitely BAD to piss off a sound mixer at a club. LOL!!

Thanks again for all the help.


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Post subject: Re: VV Structural question.
Posted: Sun Jul 07, 2019 8:41 am
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Just watch that guy walk across the stage, trip over the guitar cord he wasn't paying attention to. The plug rips out of the amp, but not before pulling it over and falling flat on its face. The weight of the speaker crashing down breaks the baffle right at the top.
I've seen many a particle board baffle broken up there. Plywood is stronger. A 3/4" x 3/4" oak strip glued in at the top can buttress that weak point.


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