Need Advice For One Pair of PA Speakers

[zhillsguy]

I have been tasked with installing a system for my neighbor in his metal workshop/building. It is open on two sides with a closed back and one wall separating the (roofed over) open area with the paint booth/office. The system equipment and sub will be located in the open area at the corner of the two walls. I didn't measure, but the open shop area is about 25' x 25'. He will be using it daily for background/working music, but wants to be able to crank it up within reason for the occasional party.

We will be flying two speakers overhead and I will be building a standard ported box with a PA460-8 for the go-with sub. This system needs to be functional, not necessarily "pretty". Used main speaker and amp equipment is in order to maximize value.

Options: I know most of the cheaper brands (Behringer/Harbinger, etc.) of pa speakers are junk, but are there any "gems" to be had in the bunch? My first gut reaction was to get a pair of Yamaha S115V's.... but even used they are a little pricey, and they are huge for hangin'. I think 12" two-ways are what is needed here. What about Peavey, EV, JBL, or other brands? Any particular models to look out for locally? I found a pair of EV SX300's for $300 that have great reviews at the usual places.

I want to set the budget to about $300 for the speaker pair. I was also looking at the BFM Simplexx line, since that is my woodworking skill limit. Are the 1x12 (or 1x15) PA tops at least equivalent to a commercial brand in the $300 used range? There isn't much info in the build forum what the components are, SQ, etc. There don't seem to be too many "plain" PA speaker designs available, and I would rather buy used if possible.

[billfitzmaurice]

Re: Need Advice For One Pair of PA Speakers

The S12 is at least the equal of a $499 commercial speaker, the S15 at least the equivalent of a $599 commercial speaker. What you might be able to find used you never know. You also never know how well or how badly the previous owner treated it.

[Sydney]

Re: Need Advice For One Pair of PA Speakers

...I want to set the budget to about $300 for the speaker pair. ...

Very tight budget. I've heard numerous speakers that would do the job, but don't know if they could be found used at that price point.

[msibilia]

Re: Need Advice For One Pair of PA Speakers

If you are doing PA460 subs, I have built some I am happy with. Single sheet of 3/4 plywood. 85 lbs per box loaded with driver and easy enough to carry by yourself. Cutlist may save you some time. Measurement was at 2.32 V since it is a 5.4 ohm driver. Probably should have done it at 2.83V. First graph is single; second is quad.

[Brian Steele]

Re: Need Advice For One Pair of PA Speakers

Are you sure 12x1 or 15x1 tops are required? The space seems fairly small - my living room is about the same area and my two Blastoramas are enough to "light it up". How loud are these "parties" expected to get?

[zhillsguy]

Re: Need Advice For One Pair of PA Speakers

Are you sure 12x1 or 15x1 tops are required? The space seems fairly small - my living room is about the same area and my two Blastoramas are enough to "light it up". How loud are these "parties" expected to get?

I am not sure how loud.....he knows nothing about equipment, but I have used my system over there. I have been intrigued by your Blastoramas for a while and have considered building a pair for use when less is needed than the pair of Cheap Thrills I use regularly. That is actually a very good idea.... and at their cost he can afford four.

[Brian Steele]

Re: Need Advice For One Pair of PA Speakers

I am not sure how loud.....he knows nothing about equipment, but I have used my system over there. I have been intrigued by your Blastoramas for a while and have considered building a pair for use when less is needed than the pair of Cheap Thrills I use regularly. That is actually a very good idea.... and at their cost he can afford four.

If by "Cheap Thrills" you're referring to the SEOS 12x1 design, then if that's more than enough for your friend's needs, then the Blastoramas might just fit the bill. Note that Eric has a design around the same 8" driver and a waveguide that should perform even better, but at a higher cost, of course. But it's worth consideration.

Some notes on the Blastoramas:

1. The 8" driver used in the Blastorama is pretty good, but it's happier doing midrange than bass. The alignment I use for it in the Blastorama has a low Fb which allows you to extend the bass response down to 60 Hz (at lower playing levels, of course) with a little EQ between 60 Hz and 100 Hz. I suggest experimenting with a shorter shelf vent if you want a little more midbass "punch" without having to use EQ.

2. The x-over in the Blastoramas is designed specifically to address the non-flat response of the GW 2x5 piezo tweeters. Using another 2x5 piezo (or any other tweeter) in place of the GW is not recommended, unless you adjust the x-over to suit. Even then, the GW piezos are not the most consistent drivers - I suggest buying four, then using two of them that have the closest matching FR curves.

3. I suggest leaving the speaker baffle removable (i.e. just screw it into place, don't glue it in). If he wants to do a tweeter upgrade in the future, all it would require is new baffles, not new boxes. Since the Blastorama build, I discovered the wonders of the "frankenpiezo", and then there's also a few wave-guide loaded tweeters now available from PE that look like possible upgrade paths...

4. Lightly stuff the area behind the center brace (which must be mounted at the angle seen in the diagram). Use something like chicken-wire mesh to prevent the stuffing from entering the vent

What are you planning to use for amplification?

[kirk78h]

Re: Need Advice For One Pair of PA Speakers

the Blastoramas might just fit the bill. Note that Eric has a design around the same 8" driver and a waveguide that should perform even better, but at a higher cost, of course. But it's worth consideration.

Brian, I've thought about building a pair of your Blastoramas as well. I've seen the waveguide design that you mention as well as one in the Econowave thread (although I think the horn is NLA). I've also wondered if a high efficiency dome like the Vifa DX tweeter could be used. I think the sensitivity is in the mid-90's; it's cheap and pretty well-regarded. Do you think that would offer any advantage over the piezos?

[Brian Steele]

Re: Need Advice For One Pair of PA Speakers

Brian, I've thought about building a pair of your Blastoramas as well. I've seen the waveguide design that you mention as well as one in the Econowave thread (although I think the horn is NLA). I've also wondered if a high efficiency dome like the Vifa DX tweeter could be used. I think the sensitivity is in the mid-90's; it's cheap and pretty well-regarded. Do you think that would offer any advantage over the piezos?

With respect to frequency response, almost any tweeter would be better than the GW piezo, LOL. Not only is its response decidedly non-flat, the response is not consistent either - four GW piezos may give you four very different measured frequency response curves, so there's no guarantee that the results I achieved would be matched by someone else doing the same build using the same components. Note that BFM neatly tackles this issue by using multiple piezo elements in his design, so their response averages out. In the Blastorama there's only one piezo per unit, so... .

On the plus side is the x-over for the piezo is usually a bit cheaper (smaller inductor, etc.) and of course it's cheap to stock spares just in case you manage to blow one up. Finally the physical design offers some built-in-protection (no dome for prying fingers to push in, etc.). There's no need to place a grille over them. The piezos are therefore a good fit for the Blastorama's original intended purpose (a "party speaker" that I could lend to my kids to knock about with and not have to worry too much if they manage to blow something up), but there's no doubt the design can be refined for better performance. In fact, my design includes a removable front baffle to allow for just such a refinement without having to rebuild the entire speaker box .

If I was looking to refine it, I'd consider a number of options:

1. Go with a "frankenpiezo" - this is a GW 1016 piezo horn with a GRC 1016 piezo back, with some damping added to the chamber holding the piezo element. The combination can produce a result that measures within +- 2dB from 3kHz to over 15kHz, all for a price of just over $4. And no change to the baffle would be required. There is likely going to be minor drop in efficiency at the top end, but it may not be anything to worry about.

2. Go with any one of a number of horn-loaded or waveguide-loaded tweeters - this is a more expensive option but will likely produce audibly better results. There a number that look like they'd work without any serious box redesign (i.e. they'd fit on the baffle with the Beta 8A). One of those I'd been looking at is the Vifa Tymphany BC25SC06-04 (http://www.parts-express.com/vifa-ty...eter--264-1028). At 96dB/1W/1M, this will likely have to be padded down a little (it's a lot easier to decrease rather than increase efficiency to meet a target response). There are a number of other possible candidates that could work too. The negative for this approach is that a grille will have to be considered for a number of these tweeters to protect them from physical damage.

Both 1 and 2 would require an x-over redesign of course, but tools like PCD make the design work a lot easier than it used to be. Basically design for the best combination of smoothest transition, low distortion and power handling between the midbass driver and the tweeter, then fix the rest by EQ, similar to BFM's design philosophy.

The Blastoramas, along with the subwoofer are about to get another workout again - youngest minion says she wants to borrow them for a "class party" this Friday. The last one they had, they didn't use the sub (I used dynamic EQ on the amp to extend the response of the Blastoramas to 60 Hz), and ended up turning the party into an impromptu "dance club" and charging an entrance fee to other students, LOL. OF course they were running the Blastoramas at a level that made the amp's limiter indicator look like a power light (I used the amp's DSP settings to limit its power output into the Blastoramas). Let's see if they continue to survive this time around.

[Brian Steele]

Re: Need Advice For One Pair of PA Speakers

Here's a frequency response graph that might be of interest, both taken using HolmImpulse and my calibrated Dayton mic this morning. The mic was placed 1M from the speaker and both were mounted on stands that lifted them about 1.5M off the ground. Everything about 1kHz is just the speaker, below that the room starts to have its effect. The measurement was taken in the middle of my living room, so I think the measurements from about 200 Hz up should be dominated by the speaker. The test signal was a swept sine wave at a fairly decent volume (can't tell you what it was however, as my SPL meter is currently short a battery).

The measurement compares the response of each Blastorama (forget where it says "subwoofer" - that's actually Blastorama 2), taken on the tweeter's axis. The 2dB "hump" at 700Hz featured by one Blastorama is interesting, and I suspect is caused by inadequate or improperly-placed stuffing in one of the speakers. Apart from that there's no noticeable difference in output between the two speakers until around 4kHz and above, where the piezos take over. The distortion characteristics of each piezo are VERY different.

[TerryLewis]

Originally posted by Brian Steele
On the plus side is the x-over for the piezo is usually a bit cheaper (smaller inductor, etc.) and of course it's cheap to stock spares just in case you manage to blow one up. Finally the physical design offers some built-in-protection (no dome for prying fingers to push in, etc.). There's no need to place a grille over them. The piezos are therefore a good fit for the Blastorama's original intended purpose (a "party speaker" that I could lend to my kids to knock about with and not have to worry about essay agency and if they manage to blow something up), but there's no doubt the design can be refined for better performance. In fact, my design includes a removable front baffle to allow for just such a refinement without having to rebuild the entire speaker box .

Hi Brain,

I've just seen your latest projects - Blastoramas V2 and the "Chick-Run Blastoramas". You're making amazing things! Would you recommend Pyle PDS222 drivers? You mentioned that the response isn't very consistent. I know they are cheap, but I don't want to mess with the delivery and the whole process of ordering (just don't like it).

[Brian Steele]

Would you recommend Pyle PDS222 drivers?

Based on my experience with them, unless you're prepared to buy several and measuring their frequency response and impedance to find a matching pair, I really can't recommend them.

[STIchris722]

I quickly read through this, but the first thing I thought of were the room acoustics. I suspect a concrete floor as it is a shop. Is it a steel building or a steel workshop? I couldn't gather that clarity from the OP. If they are bare corrugated steel walls, you're going to have a fun time with those acoustics. Hopefully they put insulation up before the steel was fastened to the verticals.

My father's shop is 35 x 35 and we used four (4) 6.5" 2-way bookshelf speakers to fill it. Plenty loud; loud enough that you can't talk comfortably over it. Just food for thought.

[Mike C]

I quickly read through this, but the first thing I thought of were the room acoustics. I suspect a concrete floor as it is a shop. Is it a steel building or a steel workshop? I couldn't gather that clarity from the OP. If they are bare corrugated steel walls, you're going to have a fun time with those acoustics. Hopefully they put insulation up before the steel was fastened to the verticals.

My father's shop is 35 x 35 and we used four (4) 6.5" 2-way bookshelf speakers to fill it. Plenty loud; loud enough that you can't talk comfortably over it. Just food for thought.

Those were my first thoughts as well,

I can imagine any system that has some low end to it making everything in the building buzz and vibrate including the building itself.
I know of a room that all the walls and ceiling are corrugated sheet metal with a concrete floor and people always book events in there
including full on live bands.