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Author Topic: TOPS FOR LABS  (Read 44957 times)

Dave Rickard

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Re: TOPS FOR LABS
« Reply #10 on: November 16, 2006, 11:04:30 am »

Jens Droessler wrote on Tue, 14 November 2006 16:01

Of course the X-Tro would be suitable for LAB subs, as the requirement for the Punisher hornsub is nearly the same: Needs to play down to 90Hz, has to have meaty lowmids.

Don't get me started with Bill Fitzmaurice' stuff. I think people building LAB subs want a PROFESSIONAL solution on top of them.

Jens,

I'm having trouble understanding why you consider the X-Tro to be more professional than the DR300.  When it comes down to it, both are DIY.  Both can look good or look bad.  To use either of these with a rider, phone calls and explanations would be necessary.

Are you talking about appearance, performance, or both?  Please explain.

Dave
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Dave
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DAVID_L_PERRY

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Re: TOPS FOR LABS
« Reply #11 on: November 16, 2006, 11:35:09 am »

Jens is a big contributor on the speakerplans.com web site and we have had this debate about the DR's before. Quite simply he does not accept that the folded horn can work for vocals.  He tends to put it in more colourfull language.

I was massively skeptical about the DR cabs so I built one to test before building the second (albeit with limited RTA and listening tests against other mid range cabs).

Once Time alligned and eq'd they sounded great for my needs (but it was a long time to sort out the initial problems - wrong driver choice crossover / eq)

The xtro was bigger and required more amplification, but was a definite option before building the DR

I dont want to get into fighting the DR corner for use with lab subs as I dont have them....

Dave
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Antone Atmarama Bajor

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Re: TOPS FOR LABS
« Reply #12 on: November 16, 2006, 12:00:53 pm »

I think what would be most interesting would be to show either, impedance graphs, and 3D MLS or 3D Decay Sweep.  To see where coloration in the horn will occur.

    That would be a little more telling about What coloration the DR's have.  Phase Response of the "Drivers Time Aligned"  Would be nice also.

    I find it unfortunate that very few products will show Decay over time.  Because that certainly tells a much bigger story.  Than just frequency response.

    I think this is where the major difference between horns and dirrect radiators will be found.

Antone-
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peter.golde

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Re: TOPS FOR LABS
« Reply #13 on: November 16, 2006, 01:55:07 pm »

I wish I had better test equipment/software, but cant justify the cost right now. It would certainly answer your questions. If you know of some good software that doesn't cost so much, please help me out.
The DR design is a compromise, like any other speaker design. They do have some coloration and are sensitive to eq, because they are very efficient speakers, the trade-off is in linearity. That being said, it doesn't take an excessive amount of eq to make them sound great, it also doesn't take much eq in the wrong places to make them sound real bad. What they do excel in is in transient response, they are very dynamic, and there is no crossover through the vocal range. I a/b listen tested the DR250 against MI grade boxes from EV, Cerwin Vega, JBL and found it sounded (listening with no eq) as good or better and kicked butt in the midbass, even dual 15 boxes didn't have the kick of the little horn loaded 10.
Again this is my experience using this box vs. MI grade stuff. IMHO it is a very useful box for very little money. Half the size and weight, 20% of the cost, and higher output with much less power. I think it makes sense for anyone considering purchasing MI grade speakers, don't have a lot of cash, and can make sawdust without cutting their fingers off.
I didn't intend to come here to push this stuff. They are a very complex time consuming build, and have virtually no resale value.
Also I think anyone using these isn't worried about riders.
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Jens Droessler

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Re: TOPS FOR LABS
« Reply #14 on: November 16, 2006, 06:17:03 pm »

Ok then, let's talk a little...

@ Mike Butler: There are many good DIY tops out there, whereas the Fitzmaurice tops are for people who don't know better. Physics don't work the way these DR-tops are designed. Ask other professional cab designers about it. Mids don't bend, for example. Multiple, non-angled HF drivers or even Piezos aren't professional. Nothing on his site can work as a true line array. His performance claims and comparisons are outrageous (at best!).

I have not built a DR-cab (I design cabs myself, and I know they won't work as I want cabs to work), but I heard them. They can't compete with real designs, no matter if professionally manufactured or DIY.

@ Matt Loretitsch: NOBODY said that measurement is silly, but PROS know that RTA measurements are basically worthless. They tell us as good as nothing. If you want to measure a system or a cab the right way, you need at least a waterfall spectogram, an impulse response, distortion measurement over frequency AND power and some more things. A frequency plot tells us actually NOTHING about how we will perceive the sound. It can be completely flat and sound like crap, and it can go pretty wild and sound really good (especially indoors, because the RTA doesn't know anything about the first wave law or Haas).

@ Dave Rickard: It's performance, also performance vs. size. See above, why. The worst thing would be the mids performance. From second sources (one of them is here) I know that Mr. Fitzmaurice himself KNOWS that the only way of getting mids to be heard is by masking the mids with the HF drivers output (trick the ear in believing to hear the mids).

@ DAVID_L_PERRY: It's not folded, it's bent. It's not a matter of believing. I know this simply can not work as intended. Every speaker designer or everyone a bit into acoustics knows... It is trickery, not the real deal. But even if it was folded, that wouldn't help much. Mids NEED horns as straight as possible.

@ Antone Atmarama Bajor: Right on!

@ peter.golde: I would be REALLY REALLY surprised if transient response would be really good on these (measured!). Don't confuse transient response with massive clean lowmid output (what his designs can surely do!). It's a mistake you wouldn't be the first committing it.

@ all: I think the DR design can work very well on upper bass and lowmids (up to say 250Hz). That's where folds/bents too far away from the horn throat start to be problematic. Make them bigger, add some cone mids and less but better HF drivers and go for it. I don't see how the original design could really work like intended (or let's say as advertised) with only two ways. There is a reason why EAW, EV, JBL and so on go threeway in the top on the big systems (to which BFM compares his DRs).

NEVER underestimate the human hearings ability to 'clean up' a mess of sound. I tested it a lot. In some designs with mid drivers working from 800 - 2kHz most people didn't even notice when the mid driver was turned off (WITHOUT changing the crossover so the range would be covered by other drivers. There was a big fat GAP!)until there was an AB comparison.

Again, I wish I could get over to UK and USA to demonstrate the difference between DRs and real tops. I wouldn't say that the DR cabs aren't a step up from ultra-cheap china boxes or JBL TR-cabs (and everything in the like), but they can't even compete to good middle-class equipment.

BTW: By admitting that the LAB sub needs tops with beefy lowmids, because it plays only to 80 to 100Hz, you already proved me right (can I say that this way?).... Of course you can still measure energy from the LAB at least to 250Hz, but nobody wants to HEAR this energy.....
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Antone Atmarama Bajor

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Re: TOPS FOR LABS
« Reply #15 on: November 16, 2006, 07:11:31 pm »

     I am interested in Davids, "coaxial horn".  I'm wondering how having the discontinuity of the second horn mounted in the larger horns throat effects the larger horn.

One question I have is:  Should the Volume Displaced by the concentric small horn be compensated for?

    What does it do to dispersion at the high cut of the large horn?

    Does it cause more reflected energy, or improve polar pattern?  Maybe something like that can be redesigned to incorporate a Phase plug instead of having a large object living in the throat.

    You should take an impedance chart of the Horn with and without the concentric horn.  You may be able to see what extra reflections/coloration is introduced. and if it changes the Low cut of the horn.

Antone-
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DAVID_L_PERRY

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Re: TOPS FOR LABS
« Reply #16 on: November 17, 2006, 05:04:55 am »

Antone Atmarama Bajor wrote on Fri, 17 November 2006 00:11

     I am interested in Davids, "coaxial horn".  I'm wondering how having the discontinuity of the second horn mounted in the larger horns throat effects the larger horn.......You should take an impedance chart of the Horn with and without the concentric horn.  You may be able to see what extra reflections/coloration is introduced. and if it changes the Low cut of the horn.

Antone-


Unfortunately had a garage clear out this weekend and the co-axial mock up got the chop and found its way into the bin....

The design is nothing new at all though, based upon countless other co-axial horn designs.  It was designed using Hornresp.  the only advice I could get for designing it to include the HF horn was to remove the area of the HF horn from the throat exit.  It worked suprisingly well but could not extend low enough to suit my needs, maybee that was a function of the co-axial arangement....

Regarding the DR cab, all I can say is that I did what I feel to be a pretty detailed assesment of the DR with the tools at hand before putting anymore time building another box.  Myself and two other PA providers where present during all the tests.  I was not willing to put tha vast amount of time into another build if the cab sounded just ok.

I often feel that people get way to hung up on the finite analysis of sounds system...does it sound good, does it sound better than what I compared it against...this is all that really concerned me. Was I comparing it against Danley or EAW cabs...not at all.

I however have no concerns at all with rider issues...small time PA hire only.

Cheers, Dave
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Raj Sookraj

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Re: TOPS FOR LABS
« Reply #17 on: November 17, 2006, 05:37:45 am »

I think it's time for a "Top box" shootout!  A DR250 was measured at the 2005 Prosoundshootout however, there were no other top boxes there to compare it with.  How about a DIY Unity Horn?  There are a few people who have made clones but how does it sound compared to others?  Also, if anyone knows, how do you pick those sealed back drivers for a Unity Horn?
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Mike {AB} Butler

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Re: TOPS FOR LABS
« Reply #18 on: November 17, 2006, 08:29:29 am »

Jens Droessler wrote on Thu, 16 November 2006 18:17



@ Mike Butler: There are many good DIY tops out there, whereas the Fitzmaurice tops are for people who don't know better. Physics don't work the way these DR-tops are designed. Ask other professional cab designers about it. Mids don't bend, for example. Multiple, non-angled HF drivers or even Piezos aren't professional. Nothing on his site can work as a true line array. His performance claims and comparisons are outrageous (at best!).


Jens,
Re-quoted from my original post:
(Mike Butler) "I agree, what he tends to do.. I would not want to do in my designs - I was trained differently."
I agreed with you.. his approach is certainly not the way I was trained and educated to do when designing speakers. And yes, the uninitiated will jump at the chance to DIY anything to save money. But you do have to admit, this site has done more to bring business to his site than we as purists would like to admit.
My own issue is that many of the folded bass horn designs of today seem to violate all of the traditional wisdom of the mouth size equating with the lowest frequency the horn will reproduce.. before the driver unloads from the horn and turns into a direct radiator.. and Fitz' designs seem to do this all the time.. so I'm left wondering just what the benefit is to all the labyrinthine mazes created. Sure, you can put a nozzle on a hose to get more pressure.. but at some point, it has to unload.
Anyway, we are hardly in disagreement. I just find it amazing that so many people are building and using these things..
Best Regards,
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Jens Droessler

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Re: TOPS FOR LABS
« Reply #19 on: November 17, 2006, 10:33:54 am »

@ Mike Butler: I didn't think you disagreed. I just wanted to clarify my statement. For the other things, I think you can find as good as any working design in some slightly changed form from other designers. Everybody in the speaker designing biz has tried around before he got good results, and most of them know that it won't work like this. That's all I wanted to express... I really don't care how these tops work on bass. It's nothing I'd expect from a top anyways. But good mids, THAT'S what a top is about. The music comes from the mids, not from some trickery to fool the ear into hearing them. OF COURSE the 'fake' mids seem somehow to sound good, the hearing does a good job on that, but it is not the real deal. I don't say that because I believe you don't know, but just to clarify....

And of course there are some professionally manufactured, but pretty bad cabs out there too... but in my opinion the DRs are the last DIY-cabs I'd want to build.
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