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PostPosted: Tue Apr 18, 2017 5:40 pm 
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Posts: 25596
BTW, there are a few reasons why piezos have an undeserved bad rap. One is that most cabs only use one, another is that most cabs that use more than one place them horizontally. When more than one is used they tend to be all wired parallel, and most cabs don't use any kind of filtering. They're usually used in low end cabs, because they're inexpensive, and those cabs usually are very poorly engineered. If used correctly they work well.


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PostPosted: Wed Apr 19, 2017 4:34 am 
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Joined: Thu May 13, 2010 9:05 am
Posts: 194
Location: MS Coast
*like* for the education

and *like* for "piezo breath" :lol:

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-todd

5 and 8 string bass | SansAmp | Crown | 2 x J110
2 x W8 panel-mount
2 x T39 24" 3012LF
4 x OT12 2512 melded (finally done!)


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PostPosted: Mon Aug 07, 2017 9:07 am 
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Joined: Thu Oct 28, 2010 5:48 pm
Posts: 192
Location: Hartford, CT, US
Bruce Weldy wrote:
Well, it's a slow Easter Sunday here on the forum.....so, I though I'd start a little discussion.

First, an observation concerning different speakers in the same room. I have run sound in a particular venue here in town several times - pretty evenly split between a rented system that a provider brings in and the one that the band I work with owns.

I was in there last night with the same band on their system and both the owner and his son were gushing about how good the vocals sounded - and they sounded damn good to me too.

The rented system is powered JBL PRX 725 mains. The band system is 25 yr old Peavey mains.

I used both systems with the same band (a really good singer with a great voice). The new JBLs don't hold a candle to the ancient Peaveys. Why? I think it all boils down to crossover points. The JBLs are crossed at 2.4k, the Peaveys are 1.2k. The lower crossover point in the old Peaveys really lets the vocals get clean, crisp, and present. The JBLs are harsh when you hit 'em with any volume...my guess is that it's due to the lack of higher frequencies expected to be covered by the 15 inch drivers.

If crossing that high was a decision made for better sound, then why are the SRX series equipped with better drivers and crossed at 1.2k? Well, obviously it is a matter of price. Cheaper boxes use cheaper HF drivers that can't go as low and that equals crappy sound.

Now, how does this relate to our world? The melded array is crossed at 2k, but really jumps up at the 2.5k mark. That's the reason that Bill requires that you use a low frequency driver that has rising mids - this helps fill that gap. The CD option with a good driver (the NSD2005 or better) lets you cross at 1.2k. The ASD drivers use a 2k crossover like the piezos.

Having used both the melded array and the NSD2005 - while I've always been impressed with the horizontal dispersion of the melded array, the CD horn just flat sounds better. I'm convinced that it's because of the lower crossover point.

I currently stack a CD-equipped OT12 on top of a melded box - they sound good together....kind'a best of both worlds and I'll continue doing this. But personally, if I build more - I will opt for the lower crossover point and give up some of the dispersion.

Now, if I'm comparing the melded array vs. those same JBLs, I'd definitely say that the melded wins because of the rising midrange of the woofer.

In summation - my point here is that the decision to pick the melded over the CD horn (only the better driver - the ASD is crossed at the same place as the melded, so there's no advantage) can be based on a variety of factors. The melded array is a great low-cost tweeter and it sounds good.....hell, it sounds better than most of the off-the-shelf stuff that's out there. But, if you are looking for the best quality, especially in live sound, the CD horn is the hands down winner for clarity - and it competes with the higher-end boxes that cost a lot more and also use a 1.2k crossover.

And if you are going to buy off-the-shelf, then pay attention to the specs and buy a box with a lower crossover point - it will sound better.

Comments?

Bruce.
Any chance you could run either an iphone/android RTA app ( https://itunes.apple.com/us/app/rta/id298839433?mt=8 ) or PC RTA app (REW: http://www.roomeqwizard.com/index.html ) with input from a phantom powered flat condenser measurement mic (ECM8000 or similar) on
1. that rented JBL PRX 725 mains system,
2. on your CD-equipped OT12 system,
3. on your melded tweeter array OT12 system,
4. on your friend's band's 25 year old Peavey system.
This would be truly great to see!

_________________
Newest mix 8) https://facebook.com/BEATJACKERmusic "Like" appreciated :D


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PostPosted: Mon Aug 07, 2017 9:30 am 
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Joined: Fri Nov 27, 2009 11:37 am
Posts: 6037
Location: New Braunfels, TX
chris_c_ wrote:
Bruce Weldy wrote:
Well, it's a slow Easter Sunday here on the forum.....so, I though I'd start a little discussion.

First, an observation concerning different speakers in the same room. I have run sound in a particular venue here in town several times - pretty evenly split between a rented system that a provider brings in and the one that the band I work with owns.

I was in there last night with the same band on their system and both the owner and his son were gushing about how good the vocals sounded - and they sounded damn good to me too.

The rented system is powered JBL PRX 725 mains. The band system is 25 yr old Peavey mains.

I used both systems with the same band (a really good singer with a great voice). The new JBLs don't hold a candle to the ancient Peaveys. Why? I think it all boils down to crossover points. The JBLs are crossed at 2.4k, the Peaveys are 1.2k. The lower crossover point in the old Peaveys really lets the vocals get clean, crisp, and present. The JBLs are harsh when you hit 'em with any volume...my guess is that it's due to the lack of higher frequencies expected to be covered by the 15 inch drivers.

If crossing that high was a decision made for better sound, then why are the SRX series equipped with better drivers and crossed at 1.2k? Well, obviously it is a matter of price. Cheaper boxes use cheaper HF drivers that can't go as low and that equals crappy sound.

Now, how does this relate to our world? The melded array is crossed at 2k, but really jumps up at the 2.5k mark. That's the reason that Bill requires that you use a low frequency driver that has rising mids - this helps fill that gap. The CD option with a good driver (the NSD2005 or better) lets you cross at 1.2k. The ASD drivers use a 2k crossover like the piezos.

Having used both the melded array and the NSD2005 - while I've always been impressed with the horizontal dispersion of the melded array, the CD horn just flat sounds better. I'm convinced that it's because of the lower crossover point.

I currently stack a CD-equipped OT12 on top of a melded box - they sound good together....kind'a best of both worlds and I'll continue doing this. But personally, if I build more - I will opt for the lower crossover point and give up some of the dispersion.

Now, if I'm comparing the melded array vs. those same JBLs, I'd definitely say that the melded wins because of the rising midrange of the woofer.

In summation - my point here is that the decision to pick the melded over the CD horn (only the better driver - the ASD is crossed at the same place as the melded, so there's no advantage) can be based on a variety of factors. The melded array is a great low-cost tweeter and it sounds good.....hell, it sounds better than most of the off-the-shelf stuff that's out there. But, if you are looking for the best quality, especially in live sound, the CD horn is the hands down winner for clarity - and it competes with the higher-end boxes that cost a lot more and also use a 1.2k crossover.

And if you are going to buy off-the-shelf, then pay attention to the specs and buy a box with a lower crossover point - it will sound better.

Comments?

Bruce.
Any chance you could run either an iphone/android RTA app ( https://itunes.apple.com/us/app/rta/id298839433?mt=8 ) or PC RTA app (REW: http://www.roomeqwizard.com/index.html ) with input from a phantom powered flat condenser measurement mic (ECM8000 or similar) on
1. that rented JBL PRX 725 mains system,
2. on your CD-equipped OT12 system,
3. on your melded tweeter array OT12 system,
4. on your friend's band's 25 year old Peavey system.
This would be truly great to see!


It wouldn't be of any use as I would EQ every system to sound as good as could be. There just isn't the time or inclination on my part to do this properly in a non-reflective setting with three different systems.

Anyway, those graphs are available on the internet.

I'm just making a subjective analysis based on my ears. I consider myself more of a professional driver than a professional mechanic when it comes to sound. I trust my ears more than my eyes when it comes to crunch time.

_________________

6 - T39 4-25" 2-22" 3012LF
4 - OT12 2512 Melded/NSD2005
1 - T24
2 - XF210


"A system with a few knobs set up by someone who knows what they are doing is always better than one with a lot of knobs set up by someone who doesn't."


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PostPosted: Mon Aug 07, 2017 10:47 am 
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Joined: Thu Oct 28, 2010 5:48 pm
Posts: 192
Location: Hartford, CT, US
Bruce Weldy wrote:
It wouldn't be of any use as I would EQ every system to sound as good as could be. There just isn't the time or inclination on my part to do this properly in a non-reflective setting with three different systems.

Anyway, those graphs are available on the internet.

I'm just making a subjective analysis based on my ears. I consider myself more of a professional driver than a professional mechanic when it comes to sound. I trust my ears more than my eyes when it comes to crunch time.


OK. It'd be just fine to EQ all your systems to sound as good as they can. Where the RTA app comes in (even running the free app on your smart phone) is to uncover the true data about what you might've heard, or didn't hear, but couldn't objectively put your finger on it. It'd be cool to get those real world measurements of exactly those systems' phase and frequency and all that stuff the RTA app gives you, to see if the data bears out your hypothesis (lower tweeter crossover frequency is why it sounds better) as to why your 25 year old Peavey system sounds so much better sounding compared to your much newer JBL pro rental system.

_________________
Newest mix 8) https://facebook.com/BEATJACKERmusic "Like" appreciated :D


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PostPosted: Mon Aug 07, 2017 11:29 am 
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Joined: Fri Nov 27, 2009 11:37 am
Posts: 6037
Location: New Braunfels, TX
chris_c_ wrote:
to see if the data bears out your hypothesis (lower tweeter crossover frequency is why it sounds better)


Or, I can just go with the anecdotal evidence of many years of listening to and mixing on various systems.

There's a reason that higher end speakers sound better.....they all have lower crossover points or they are three way with a smaller speaker handling the 1-2khz area.

Manufacturers are in the business of selling more gear, so the lower end stuff is made to be pleasing to the eye - bigger is better.....that's why we get 2x15 cabs with a crappy little horn and a high crossover point....it's cheaper to build and more competitive to sell. JBL should be ashamed of themselves for ever putting out the JRX line....and pretty much anything short of the SRX line is lacking also.

_________________

6 - T39 4-25" 2-22" 3012LF
4 - OT12 2512 Melded/NSD2005
1 - T24
2 - XF210


"A system with a few knobs set up by someone who knows what they are doing is always better than one with a lot of knobs set up by someone who doesn't."


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