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burdizzos

[FAQ]Speaker building

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Originally posted by Emprov



With higher grade plys I've never had a problem with them. I'd never do it on cheaper stuff but, if we're talking voidless birch, I'd do it every time if I had the jig.

 

$$$$. I was tempted to use OSX again on this 1x15 box, but I went with 3/4" Fir Ply instead. $30 a sheet.

The next box is going to be higher grade ply, I dont like this stuff I'm using right now.

C7

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Originally posted by burdizzos

Speaker Building Material Sources


Parts Express


PE is my favorite and they ship worldwide.


US Speaker


Does anyone have a link to an expanded metal supplier?

 

Does PE do better than US Speaker on shipping? It cost me $13 to ship $4 worth of plastic parts that weighed less than 1/2 lb.:rolleyes:

 

Also, I'm looking for and expanded steel source locally; if I find one and they ship I'll post it. There's a place right down the street from me that might have it but I have to take a day off to go in there because they close at 4pm:mad:

C7

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Originally posted by burdizzos

...[DeltaLite vs. Delta LF discussion]...

Let me ask you this: how would you feel about two DL's, each in their own box (bigger than the one you built, say roughly the size of the average 4x10)? Loud/low enough for just about any app?

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Originally posted by takeout

Let me ask you this: how would you feel about two DL's, each in their own box (bigger than the one you built, say roughly the size of the average 4x10)? Loud/low enough for just about any app?

 

Yeah, I'd think so.

 

You'd be getting an honest 100 dB sensitivity at 55 Hz and up with a -3 dB point between 40 Hz(6 ft^3 boxes) and 47 Hz(4 ft^3 boxes).

 

That really isn't a bad idea at all.

 

If you need much more rig than that, you should be investing in a PA anyway.

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I'm trying to decide on speaker purchasing right now. I was all set to buy a couple of DLs, until I got to thinking about those Selenium 12s. I could build a really nice 3ft^3 box for one of those...

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Unles you're going to try to build some kind of ultralight box, I'd go with the Seleniums.

 

I'm considering a 1x12 with one of those to compliment my DL cab.

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My 2x15 isn't ported and it's farting. It has brand new speakers. Would it benefit from being ported, and if so, how should I go about doing so?

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Originally posted by zenfascist

My 2x15 isn't ported and it's farting. It has brand new speakers. Would it benefit from being ported, and if so, how should I go about doing so?

 

If it's farting because the speakers are bottoming out or overextending, porting will only make the problem worse.

 

 

Right now the air pressure in the cab is trying hold the speakers in place against the force of the motor. If the cab is ported, that pressure will no longer exist and the speakers will be able to move more freely.

 

 

I'd suggest that you figure out where the distortion is coming from before doing anything.

 

What sort of speakers are they?

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Originally posted by Crescent Seven

Here's an interesting question: If I'm building two cabs to compliment one another, is there a way to custom match the boxes in terms of sound and response?

C7

 

 

You can use ISD to see what the response of the two cabs would beand see where the overlap is. Assuming the cab efficiencies are matched(see below), you will get a 3 dB increase in the range where the two cabs' responses overlap.

 

You can also use the speaker sensitivities to determine the correct number of drivers for each enclosure.

 

Suppose you build a 1x15 cab for a Peavey Scorpion and then want to add a 2x10 loaded with Eminence Deltas to compliment it. The Peavey is a very efficient driver(99dB) and will be very loud on its own. The Delta 10 is only 95 dB, so you will need to have a cab loaded with two Deltas to match the level of the Scorpion.

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Thanks for the questions, guys. You just reminded me that I need to do a sealed versus ported discussion and a bit about dB increases with both additional speakers and additional watts.

 

Sealed Versus Ported

 

 

This is far better than I could do and really gets into more information than most people want, but it's worth reading nonetheless.

 

There is a chart near the bottom of the page with the pros and cons of each design.

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Increasing Power

 

 

The equation for the decibel increase for an increase in power is

 

10 * log(p1/p2)

 

Where P1 and P2 represent the power values.

 

For instance, if I want to calculate the volume difference that I'll get when I go from 100 watts to 200 watts, it would look like this:

 

10 * log(200/100) = 3.01

 

When you double power, you get a 3 dB increase in volume.

 

3 dB is an apparent increase, but to double the perceived output, there must be a 6 to 10 dB increase.

 

To get 10 dB, you'd need to increase the power by a factor of ten.

 

10 * log(1000/100) = 10

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Adding Speakers

 

 

Every time you double the number of drivers that you have, you will increase the output by 3 dB.

 

So, if you have an Aguilar GS112 and you believe their specs, you'll have a cab that is 102 dB sensitive.

 

If you add another one, you'll get up to 105 dB.

 

Add two more and you're up to 108 dB.

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So, if you have your 4 Aguilar GS112s and an Eden WT405, here's what you'd get.

 

1 GS112 with the WT405(250 Watts at 8 ohms) would result in doubling the power over the rated 1 Watt, 8 times. Given that there is a 3 dB increase every time you double power, you'd get a 24 dB increase over the rated 102 dB, resulting in an output of 126 dB.

 

2 GS112s would get you another 3 dB, resulting in 129 dB.

 

4 GS112s would gain another 3 dB still, resulting in a 132 dB output.

 

 

 

On the other hand, you could just go with a bigger amp.

 

Same cabs with a Genz Benz GBE1200.

 

1 GS112 and a GBE1200(550 watts at 8 ohms) would result in a 27 dB increase over the 1w/1m rating of 102 dB, resulting in 129 dB.

 

2 GS112s, 132 dB

4 GS112s, 135 dB

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Originally posted by zenfascist

They're Eminence Delta speakers.

 

 

Damn, those are 400 Watt RMS speakers, they should not be breaking up in a sealed box.

 

 

What are you driving them with?

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Originally posted by burdizzos




Damn, those are 400 Watt RMS speakers, they should not be breaking up in a sealed box.



What are you driving them with?

An article that I read says that sealed boxes cause the speakers to break up at high volumes and that ported cabinets always sound cleaner.

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There are no hard and fast rules on that.

 

Typically, sealed boxes handle more power. However in a sealed box the speaker can be at its maximum travel at resonant frequency which will produce distortion.

 

 

Ported enclosures, on the other hand, have a sort of built in protection for the speaker at the tuned frequency. The trouble is that as the input goes below the tuned frequency, the driver is uncontrolled and can suffer severe damage.

 

 

Still, I'm curious where the distortion is coming from.

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It's not even distortion, it's that they're just, well...farting. It sounds like they're bottoming out, even with the bass turned down pretty low. The cabinet was built in the 60s or 70s, so maybe it's just constructed poorly. I'm driving them with a Traynor YBA 200 (200 tube watts). Should I just trade it in for something better, or would it be worth trying to fix? What sort of problems should I look for?

 

Thanks for all your help, burdizzos. :thu:

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Originally posted by zenfascist

It's not even distortion, it's that they're just, well...farting. It sounds like they're bottoming out, even with the bass turned down pretty low. The cabinet was built in the 60s or 70s, so maybe it's just constructed poorly. I'm driving them with a Traynor YBA 200 (200 tube watts). Should I just trade it in for something better, or would it be worth trying to fix? What sort of problems should I look for?


Thanks for all your help, burdizzos.
:thu:

 

 

It could be a crap cab that is just too damned small for those speakers. They could very well be bottoming out.

 

Also, the resonant frequency of that speaker is 40 Hz. I'll bet it farts the worst with an open E string.

 

 

Do you feel like building a cab? I could give you the specs later this afternoon.

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Originally posted by burdizzos




It could be a crap cab that is just too damned small for those speakers. They could very well be bottoming out.


Also, the resonant frequency of that speaker is 40 Hz. I'll bet it farts the worst with an open E string.



Do you feel like building a cab? I could give you the specs later this afternoon.

 

Haha, yep, it farts on open E. Building a cab sounds like lots of fun! And I'm sure it would be cheaper and easier than a trade-in or something. I'll PM you my email or you could post the specs. Thanks again bud. :)

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Originally posted by zenfascist



Haha, yep, it farts on open E. Building a cab sounds like lots of fun! And I'm sure it would be cheaper and easier than a trade-in or something. I'll PM you my email or you could post the specs. Thanks again bud.
:)

 

It is alot of fun. As long as you have the speakers, it's definitely cheaper to build it yourself, and you get a custom box...if you're interested, I have a place here in Denver that sells vinyl for $7 a yard, several colors, including black; I just covered mine with it and it came out awesome.

 

By the way Burdizzos, I finished that cab! Sounds great. I'll post pics tonight, hopefully.

C7

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any idea what the specs are on the speakers in a peavey 412tvx? i wonder about building a custom cab to load with the speakers out of the peavey, more because i'm a tinkerer than anything else...

 

 

 

please and thanks!

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Originally posted by mlwarriner

any idea what the specs are on the speakers in a peavey 412tvx? i wonder about building a custom cab to load with the speakers out of the peavey, more because i'm a tinkerer than anything else...




please and thanks!

 

Pull one out and see what model they are. Peavey has the parameters on their website.

C7

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