Possible New Speaker Design???

[kjacobs]

I have owned a set of DR280s for over 8 years and they have done well for our sound company. However, recently I have been evaluating a new speaker building project and looking at various ideas for designs. One cabinet that really intrigues me is the KV2 VHD2 box (and its smaller VHD1 companion box). I am wondering if anyone has ever considered designing something similar and how difficult it would be to design a box like the VHD2. It includes 2-12" low drivers, 2-8" mid driver and a 1.4" horn driver. Everything is horn loaded and it sounds amazing....it looks like it would make an excellent, quite powerful pa mid/hi box.

Thoughts???

[Grant Bunter]

I orignally brought up KV2 some time back, here's the thread: http://billfitzmaurice.info/forum/viewt ... &hilit=KV2

Things to notice.
You don't just buy cabs. You have to buy their amps too, for their proprietry DSP/processing.
The cost of such systems suddenly becomes exhorbitant relative to DIY cab building costs.
You could hire a system, and reverse engineer it, but I suspect the drivers would be OEM.

In what way are you finding your DR280's lacking to the point you are looking at other designs?

[kjacobs]

Hi Grant and thanks for the reply. I went over and read the other thread for fun....

I originally built my DR280s with piezos from around 2009ish plans, before the crossover addition and changes to the design. They worked great for 6 years before performance started suffering and I found air leaks in the internal pvc radius section. That year I revamped the cabinets with crossovers from the newer plans and changed out the 12" drivers. I fixed the air leaks by filling the pvc section with spray foam insulation and modifying the piezo array with a backer to seal them as well. After all those changes, I expected miracles.....but the cabinets never sounded the same since. They were way too bright, despite rewiring the piezos a number of different ways to tone them down. I even tried rebuilding 1 piezo array and reverting back to the non-crossover cabinet. Still could not get them to sound as amazing as they did at day one when I was blown away by their clarity and detail. I had to pull them from service completely before the end of last year's concert season do to failed caps in the high freq crossover.....yessirree, 250v caps all bulged and split in the high xover. And NO, they were not overpowered and driven to destruction.

My other issue was beaming in the piezo array. While most folks probably want super tight vertical coverage in the highs, the 10 piezo array was so laser tight vertically I had to be extremely careful in setting angles between cabinets. That laser tight coverage made them very harsh when you were directly on axis, but response dropped off rapidly more than a few degrees above or below center.

Again, I loved the DR280 the first number of years they were new.....but just could not get them to perform like that after the revision, post air leak. I have since gutted them for the parts and looking for a new option to put the parts in. I have given serious consideration to the Omnitop 12, as to its easier, faster build and design. However, I am still researching ideas. I do know I want compression drivers in next set of cabinets and run them either bi or triamped.....

I am open to all sorts of suggestions at this point......LOL.

[BrentEvans]

Maybe try the compression driver horns, using (if you're not already) premium drivers throughout (not the cheap eminence ones) and running them biamped with a good DSP crossover. Start from scratch and set them up properly and use an analyzer in an open field to tune them flat as a starting point. You might just see the miracles again.

I never liked the piezo arrays either. When you measure them and look at the real results, you begin to realize that the advertised charts are smoothed significantly (as are all advertised charts, in fairness) but that smoothing covers up the radical peaks and dips that happen with the piezos that don't happen with premium compression drivers, domes, ribbons, etc.

Also bear in mind that your expectations may be different or just higher now. That tends to happen when you're exposed to good sound, or even different sound, for a while.

All that said, if you were blowing caps like that, something was probably wrong with the wiring. Even the basic piezo crossover components can take quite a beating.

[kjacobs]

I considered the comp horns in the DR280....but my plans only showed those working with the neo magnet 2512 I started with. I now have Delta Pro 12s so the magnet would get in the way.....unless there is something I don't know. I also did not want to use 2 comp drivers per box.....1 should be plenty to match the 12" in SPL. I did wire the DR280s to allow biamping....but again, did not want to use 2 comp driver per box.

[David Raehn]

Did you take the big rubber ring off of the Delta Pro 12?

It is a big honkin' magnet nonetheless.....

[BrentEvans]

There are benefits using two HF drivers (in addition to them fitting in the cabinet better). While a single driver can match in output, with two, you have half the power going to each to accomplish the same goal. Additionally, the more drivers you have in an array, the smoother the response becomes. While the difference between a single and a double might not be much in a single cab, the benefit multiples as the array grows.

Another option would be to look at the Dayton PT-2C ribbon driver. It would take 6-8 per cab to fill the space and match output, so it is not an inexpensive option, but the sound is phenomenal. I did 2 per cab in DR200s and they kept up with the woofers very nicely. In fact, they outran the woofers. They can take a lot more than their rated power very cleanly if you cross them over at 3k with a very steep filter (I always did 48db LR on those) so you might even start with 4 per cab and just see how it works.

[Bill Fitzmaurice]

You can't use a single HF driver, the height of the HF horn won't allow for it. Even the much shorter JBL VRX932 uses three.

[kjacobs]

Hi Brent.....

I can see the benefit in 2 comp drivers in easing the work load of one driver.

The idea of the ribbons is very interesting, although expensive as you mentioned. Another thought I had was borrowing from the column array designs I have seen. Maybe use 6-7 Eminence Alpha 3-8 (or 3" Faital Pros) in the front of the DR280 (with a sealed chamber behind them). I was thinking of crossing over at around 500Hz to the Alpha 3-8s. They should easily do 400Hz up to 20K.....I just do not know how they would keep up with the 12" in the horn. Wiring would also be a challenge with 7.....6 drivers end up either 5.3 ohm or 12 ohm. However, 7 drivers ends up lopsided in the wiring, but fits the front baffle better....

Ken

[Bruce Weldy]

Maybe use 6-7 Eminence Alpha 3-8 (or 3" Faital Pros) in the front of the DR280 (with a sealed chamber behind them).

Without some kind of horn in front of 'em, you'll probably get horrible horizontal dispersion.

[Bill Fitzmaurice]

250v caps all bulged and split in the high xover. And NO, they were not overpowered and driven to destruction

There's no way that 250v caps could suffer that damage if the crossovers and tweeters were properly configured. From a voltage standpoint the woofers would have blown at around 70 volts. Only very high current could have blown those caps, and the current they pass is slight, unless something is seriously AFU.

[kjacobs]

Maybe use 6-7 Eminence Alpha 3-8 (or 3" Faital Pros) in the front of the DR280 (with a sealed chamber behind them).

Without some kind of horn in front of 'em, you'll probably get horrible horizontal dispersion.

Then how do a bunch of other companies get away with using a long string of small drivers to create a vertical column array without a horn in front of them. I have never personally heard one....but would that be any different from a small SLA column???

There's no way that 250v caps could suffer that damage if the crossovers and tweeters were properly configured. From a voltage standpoint the woofers would have blown at around 70 volts. Only very high current could have blown those caps, and the current they pass is slight, unless something is seriously AFU.

I know it makes no sense to me either. I am sure I quadruple checked the crossovers before putting them in service....and I had no issues with them the first year after the updates. There was no damage to the low freq crossovers at all and I have removed all the components to save what was salvageable. I am still baffled at the cap failure....

[Bruce Weldy]

I know it makes no sense to me either. I am sure I quadruple checked the crossovers before putting them in service....and I had no issues with them the first year after the updates. There was no damage to the low freq crossovers at all and I have removed all the components to save what was salvageable. I am still baffled at the cap failure....

I blew caps in my OT12s once. They were not overpowered at all, but the diaphragm blew in my horn also.....don't know if the short in the horn caused the caps to blow or the other way around, but it drove my amp into thermal mode until I unplugged that cabinet. It went during sound check, and I'm pretty sure it was when the dumbass bass player (not my band) slapped his strings really hard....I heard the crack, but didn't notice until a little later that we had a problem.

Don't know if it can happen like that to piezos or not.

Personally, I'd go with the comp drivers....the NSD2005s if they fit. Better driver, crossed lower, and should sound better.

[J_Dunavin]

More of a question for myself, but wouldn't multiple DR250s sound better than a set or four of the 280s?
How would four DR250's per side sound, compared to the two 280s?

I know you mentioned it earlier but is this really a sound quality issue or a coverage issue?
What's your crowd size? And how far away is the crowd? I always thought of the 280s and 300s intended for long distance.

[kjacobs]

This is partly a sound quality issue and partly a coverage issue. The piezos in the updated cabinets were very bright, despite rewiring and adjusting the levels numerous times in the hi section. However, the piezos also exhibit a very narrow, pin point vertical coverage (which is good for some situations, but not so good for even coverage with fewer boxes). I did a bunch of piezo array tests in my shop and found them quite beamy dead center, but dropped off rapidly above or below center in the vertical plane.....even a couple inches made a huge difference.

We do mostly outdoor gigs anywhere from 500-2000 people....relatively sane SPL levels for our family concert series. Audience can be up to 200 ft away, but the 4 DR280s have always done well in this park venue for the past 8 years without having to resort to amplifier overdriving. I have no experience using the DR250. Was actually thinking of a new build of 8X Otop12.....and maybe using the comp driver option.