Amp Tech Thread / Ask a tech Q

[Hemisaurus]

You do it however best you can do it. The main thing is to get it air tight, and make sure the baffle doesn't buzz.

I imagine one way to do it, that will probably mean you don't have to marr the tolex on the outside would be to install a, and here my knowledge of woodworking fails me, trim or whatever a piece of wood running all the way round the inside of the cab, making a lip that the front baffle would rest on, always use screws AND wood glue on cabs, the screws keep it tighter than nails, and the glue keeps it airtight and prevents the screws backing out.

Now I think Sunn as constructor, may have more valuable info Here's some tips from two really good sites on speaker construction in general.

http://speakerplans.com/index.php?id=guide
http://www.dancetech.com/construction.cfm

[justinhedrick]

nice, right on!

now what kind of wood should i use for the baffle?

[VOLVO)))]

Use 3/4' birch plywood. You have to set in new cleats behind the baffle, since you'll destroy the old ones getting the old baffle out. Just use 1x1's, cut them into the correct dimensions, recess them deep enough for the baffle, and the grill. glue and screw.

[Hemisaurus]

Super Dense MDF. Or marine birch plywood, but for a baffle MDF would be a little less air-gappy. Observe proper precautions when cutting MDF

Dusty from Knife of Simpson did something like this to his 2x15, see if I can find a pic

[VOLVO)))]

Fuck MDF. Worthless bullshit.

[justinhedrick]

Super Dense MDF. Or marine birch plywood, but for a baffle MDF would be a little less air-gappy. Observe proper precautions when cutting MDF

Dusty from Knife of Simpson did something like this to his 2x15, see if I can find a pic

what are the proper precautions? i'm assuming it involves not injuring yourself since it is so dense?

[justinhedrick]

Fuck MDF. Worthless bullshit.

so . . . birch then?

[VOLVO)))]

MDF is sawdust and glue. It's just shitty. I'll never use it on anything.

[Hemisaurus]

Oh here we go again, Mr Mastercraftsman.

Acoustically speaking MDF is superior to birch plywood, as it is absolutely void free, but it suffers from the fact it's susceptible to water, if you plan to get it very wet, you will damage the MDF, a couple of soakings in the rain won't hurt it, submerging it in a flooded trunk will.

Birch however is more durable and weatherproof, and almost as void free (if you get the good stuff, Marine Birch) as MDF.

You see a lot of manufacturers make a shell of birch, and a baffle of MDF. You were replacing a baffle hence I suggested MDF above birch, that, and to watch Sunn's blood pressure soar

MDF is nasty stuff when you cut it, so the safety precautions are wear a mask when cutting and drilling it. You don't want to inhale it.

[Hemisaurus]

Just out of interest, what are you loading it with, and what will be the box volume once you finish?

[VOLVO)))]

-shakes fist- DAMN KIDS!

It's susceptible to any form of moisture... It'll soften up in a heartbeat, just sayin', player.

The precautions I use when I use MDF... oh wait, I don't, because it's a gigantic sheet of BULLSHIT. ^.^

[justinhedrick]

Just out of interest, what are you loading it with, and what will be the box volume once you finish?

a set of 15" ev forces. as for the volume, since i don't have the cab, i can't measure it . . . i need to get that fingered out, huh?

[Hemisaurus]

Just out of interest, what are you loading it with, and what will be the box volume once you finish?

a set of 15" ev forces. as for the volume, since i don't have the cab, i can't measure it . . . i need to get that fingered out, huh?

If you know the model number, you may be able to check out the dimensions http://peavey.com/support/searchmanuals/archived.cfm

You may find you end up porting the box, ported boxes generally need smaller volumes than closed box.

[Hemisaurus]

-shakes fist- DAMN KIDS!

It's susceptible to any form of moisture... It'll soften up in a heartbeat, just sayin', player.

The precautions I use when I use MDF... oh wait, I don't, because it's a gigantic sheet of BULLSHIT. ^.^

This from the man who insists any Behringer pedal is going to explode as soon as he nudges it with his big toe

MDF is going to hold up better than the pressed cardboard that Peavey seem to use for front baffles, when I get the time, and the skills (or borrow the skills from someone) I'll make an MDF bass that will blow your Mahogany bullshit out the water 

PS Keep taking the tablets, whenever you feel a twinge.

[VOLVO)))]

Cornholer.

[justinhedrick]

ok. i'm probably going to buy MDF. sorry sunn.

[Hemisaurus]

Hmm, after hunting about came up with the EV datasheet, and what do you know, unlike Eminence who give recommended box dimensions, EV does not  

Modelling it for optimum, it needs a massive box, because of it's high Q, but it will go low if the box is big enough, dimensions are in liters.



645 liters = 22.77796 cubic feet
1289 liters = 45.5206054 cubic feet

However this is optimum, any idea what the box is, we can plug in the values and see.

Is all this just falling in your lap? It might be better to get some 12's for the box otherwise, if bass is a thing you need.

[justinhedrick]

Hmm, after hunting about came up with the EV datasheet, and what do you know, unlike Eminence who give recommended box dimensions, EV does not  

Modelling it for optimum, it needs a massive box, because of it's high Q, but it will go low if the box is big enough, dimensions are in liters.



645 liters = 22.77796 cubic feet
1289 liters = 45.5206054 cubic feet

However this is optimum, any idea what the box is, we can plug in the values and see.

Is all this just falling in your lap? It might be better to get some 12's for the box otherwise, if bass is a thing you need.

yes, i have the 15s already, i have the box. i need a smaller 2x15 than the kustom one i already have. boom.

[Hemisaurus]

Is it for guitar or bass?

Say we took a typical enclosure very small as it originally house 12"'s 32" x 17" x 12" basically a box with just enough space to fit the drivers and not too deep, that's gonna get you 180 liters, if you'll forgive my metricness.

In this case by the box is so small there's no difference between a sealed box, and a vented box, if you tune the vent flat, and even if you don't there's not much extra to gain



For guitar this might rip, as it will be right in the punch range, even bass might sound OK, as long as it was a more rock bass and a less sub/dub/sunn bass. You're gonna need a VERY big box for those speakers if you want <80Hz

Suck it and see you might like it. Is the front baffle already off the box, as in is it already useless?

[justinhedrick]

Is it for guitar or bass?

Say we took a typical enclosure very small as it originally house 12"'s 32" x 17" x 12" basically a box with just enough space to fit the drivers and not too deep, that's gonna get you 180 liters, if you'll forgive my metricness.

In this case by the box is so small there's no difference between a sealed box, and a vented box, if you tune the vent flat, and even if you don't there's not much extra to gain



For guitar this might rip, as it will be right in the punch range, even bass might sound OK, as long as it was a more rock bass and a less sub/dub/sunn bass. You're gonna need a VERY big box for those speakers if you want <80Hz

Suck it and see you might like it. Is the front baffle already off the box, as in is it already useless?

it's for guitar. the front baffle is NOT uses, but it is liek this: the top half of the cabinet as the baffle for the speakers, the bottom half has the scoop or whatever you'd call it for bass frequencies, so all of that would come out, and i'd just make a straight baffle for it.

[Hemisaurus]

What's the model # of the speakers, or even the range? Too many Peavey's to guess at.

If we're assuming that 32 x 17 x 12 box (180 liters) that's almost perfect for a ported pair of Eminence Delta 12" only -3dB at 50Hz

[justinhedrick]

What's the model # of the speakers, or even the range? Too many Peavey's to guess at.

If we're assuming that 32 x 17 x 12 box (180 liters) that's almost perfect for a ported pair of Eminence Delta 12" only -3dB at 50Hz

i don't have it in front of me. been trying to track it down on the webs . . . can't find it.

i am going to be using 15s because i already have them hemi, i'm not buying 12s.

[Hemisaurus]

Of course if you wanted MORE bass from what you have you can overtune the port for a giant peak, be 3 dB down @ 50Hz over 0dB between 60-200Hz, and only use one of your drivers.



Course if the cab is bigger than my guesstimate and nearer 360 liters you can do this with both drivers.

I had figured you could trade he 15's for 12's

[justinhedrick]

Of course if you wanted MORE bass from what you have you can overtune the port for a giant peak, be 3 dB down @ 50Hz over 0dB between 60-200Hz, and only use one of your drivers.



Course if the cab is bigger than my guesstimate and nearer 360 liters you can do this with both drivers.

I had figured you could trade he 15's for 12's

do you have any 12s? is that what you're saying?

[Hemisaurus]

No.