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Author Topic: Hornsub shootout  (Read 43977 times)

leon douven

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Re: Hornsub shootout
« Reply #10 on: July 24, 2005, 02:58:35 PM »

Verry cool... I wish I could be there, like Tamas I'm verry far away (Netherlands)... would it be possible for me to join in???

I wonder why nobody is interested in Having the EAW KF940 in the ring... seems like a verry serious contender...

Hope you guys pull it of

Best regards
Leon Douven
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Wayne Parham

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Re: Hornsub shootout
« Reply #11 on: July 24, 2005, 04:11:33 PM »


I'd love to see you there.  I'd also love the EAW KF940 to be there.  No one should be excluded, I just didn't mention everyone.  I knew some of the regular participants would want to test-n-tune, and so I just listed them.  But they're certainly not the only ones.  It would be great to have a demo of every horn out there to evaluate.  Everyone will be welcome.

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Wayne Parham
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Gary Perrett

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Re: Hornsub shootout
« Reply #12 on: July 24, 2005, 11:40:07 PM »

Unfortunatley, as Bink discovered, the more...isn't always the merrier.

As the list grows, so does the time necessary to give each contender a fair shake.

One example comes to mind particularly, (in the amp shootout) and that is the DIGAM amps. they were sumarily dismissed for their inability to meet spec. The problem is, as I understand it, they would not come to full power with a test tone. We asked why this was and the MFG explained, the amp saw the signal as feedback, and so limited its output to protect the drivers.

This would seem to be in line with our experience, as we drove a pair of Community CPL23's with this amp and no mater how hard we drove the amp, it never distorted, or harmed the 8",2 way's (and they got REALLY LOUD... very impressive!) We found that a single DIGAM 5000 (digam series)(17 LBS, 1 rack space, capable of operation on a "15 amp hotel outlet") put a MAC 5000 to shame on 4 LABsubs, and then we added 2 more (3 per side stereo) and drove them ALL DAY, out doors,(the sound was THUMPIN 3/4's + miles away) with NO problems what so ever. Mark Seaton, if you are out there? Mark had a chance to use this amp at the (SPL labs facility)Servo lab, and commented he heard absolutly NO power compression, when played through their SPL series II and B DEP series subs. He was VERY impressed.

I guess I just wanted to caution you to not " bite off more than you can chew". Perhaps you could contact Bink, and get some practical advise from him. I know he had some regrets, following the shootout.

Gary Perrett
Twilite Zone Productions
 
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Wayne Parham

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Re: Hornsub shootout
« Reply #13 on: July 25, 2005, 10:37:35 AM »


You're right, it will take some time to setup and evaluate each one.  We'll want the usual frequency response, distortion and SPL measurements.  I'd like to see how far we can go above 45VRMS too, for those willing to risk the push.  And I'd want to see how each acts after a period of continuous power, so you're probably looking at an hour per system, after setup.

I'm really interested in seeing the Litzhorn get a fair shake, because I think it represents a significant improvement over the LABhorn.  I'd also like to get some readings on Fitzmaurice's designs.  And of course, I want to give my 12Pi a test run, see how the cooling system and push-pull arangement stack up against the others.

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jeffhtg (Jeff Kenney)

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Re: Hornsub shootout
« Reply #14 on: July 25, 2005, 04:07:41 PM »

I'd really like to see a common touring sub in one of these shootoffs... ormeybee something like the kf760.. Too bad i dont have any and its to far away for me to help anyways.
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Tom Danley

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Re: Hornsub shootout
« Reply #15 on: July 25, 2005, 07:21:47 PM »

Hi Wayne

It is somewhat humorous to me that you have gone from being the most outspoken skeptic of the lab sub (and Unity Horn for that matter) and there approach’s some years back on Audio Asylum, to using the same lab-12 driver and building a similar bass horn.  
Kind of cool in a way.
I would take exception to your reference “ an improvement over the lab sub” however for the following reasons.
The Lab sub’s package and intended use in groups was defined by the LAB folks who were around back then, proportioned to pack in a truck in all dimensions.

The size and weight of your larger box make it a rather different horn as well as more difficult to move or get through some doors.  
Of course that doesn’t matter in the home but that wasn’t what the lab sub was for.
Also, if your software allows it,  compare I^2 R heating vs acoustic power as you enlarge the front volume “large enough” to “fill in” the dip (which is highly overstated in your computer model of the lab).
You will see that the enlarged volume also produces more reactance (visible in your impedance model vs the lab), more excursion generally (and therefor distortion) and a lower excursion limited maximum output.  It would appear your rear volume is larger also, again the more rapid increase in excursion below band is an indicator it will be easier to damage accidentally with vlf, also fortunately not an issue in the home given the head room.
The lab sub was designed for live sound, for maximum output in a group, by adjusting all the proportions to get the greatest output and lowest heating in that package size.
Brad’s sub IS better than a lab, it a pair, it has a larger mouth, longer horn path and boundary coupling but would be more difficult to pack up after a gig.

.
Also, I think you do Eminence a disservice with frequently mentioning of “thermal failures” relative to your cooling rod.
There were some failures in the beginning due to a glue curing problem but according to Eminence (who I called about this) there is no failure problem and the lab-12, it is in the top sellers they have.  Oh yeah, let’s not forget that they were the only ones to step up to the plate and develop a goofy driver like the lab-12 (the same one you thought was all wrong back then) to my spec’s for  the project.   It is a good reliable driver at a good price.

That leads me to a couple  hypothetical questions about your sub shootout.
Lets pretend there were two subwoofers that had the same low cutoff but one was 20 cu/ft and the other 40.
To compare it to the 40 cu/ft model, would it be fair to look at two of the smaller ones (the same total cubic volume) with one total Watt?

What if one sub had higher sensitivity at 100Hz but less at 30Hz compared to one that was “flat”, how do you rate that sub?

What if one given speaker had low frequency directivity giving it +12 dB more output but was only going down to 40 Hz?

What if one sub was 4 ohms and another 8, do you use 2.8 Volts or an impedance blind approach like “1Watt” being Voltage = sqr root of R-min.

How do you propose to “score” such an event anyway?
You should give this some thought and planning.

Are you going to listen to the subs too? If so, what do you have that isn’t fatiguing and will keep up with this kind of gear?  
This is no small task if your talking about multiple Lab subs, (if you have not actually heard them yet).

Your shootout can better jump start your 12 pi sales if you get more of the “big name” products in as well.  Often, the greater the perceived position (and cost) in the industry, the less that perception is based on measured performance or what is judged by side by side comparisons.    Anyway, you will find it enlightening if you can get a selection of commonly used pro-subs  and instrumentation for side by side comparison.
Be sure to get some good vented boxes too, hearing this difference (a good horn like the lab vs a vented box side by side) can be very striking.
Do some quick basic measurements at increasing levels combined with listening.  
Be careful, your ears will get tired, start soft.
Have fun,

Tom Danley
Danley Sound Labs
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Wayne Parham

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Re: Hornsub shootout
« Reply #16 on: July 26, 2005, 12:16:40 AM »


The history of the 12Pi project is outlined in the 12Pi thread, so there's little point in re-hashing it here.  But I want to clarify that the 12Pi design is available for people to use, provided it isn't sold and credit is given, just like the LABhorn and many other DIY designs.  It wasn't about "jump starting" sales, it was about making something the best possible.

As for your comments about heat, it seems to me the best thing to do is to examine it, see if it might be a problem and if heat reduction is possible.  That's exactly what I've done.   For example, if you measure the pole piece of the LAB12 at 40VRMS, you'll find that it is very hot.  The air surrounding the voice coil isn't hot at all, so this means most heat is radiated.  An easy way to remove it is to conduct it away.

When running a LAB12 at 40VRMS, 40Hz, I found that it is not damaged by excursion, even in free air.  But it does get extremely hot.  That leads me to believe that probably most failures are heat related, not excursion related.  It doesn't mean that I think there is an abnormal number of failures, it means that I think when there is a failure, it is probably a thermal failure.

After all, the addition of the cooling device is a simple matter of adding a 3 inch pipe to the drivers in existing LABhorns, so it seemed to me to be a worthwhile thing to look into.  Even if it only gained a little bit of reliability and/or power handling and output, the gain would have been worth it, don't you think?  From what I've seen so far, it is significant.

I'll have some of the cooling devices available for people to try at the hornsub shootout, if anyone is interested.  They'll bolt right on.  I'm already committed to using them on my horns, and others might like trying them too.

There will be lots of other horns there besides 12Pi horns and LABhorns.  Everyone is welcome, and I'm hoping to see and hear a variety of systems.  That's what we plan to do and you're welcome to join us if you wish.  The hornsub shootout isn't intended to polarize the market, it's intended to bring people together.

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Ivan Beaver

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Re: Hornsub shootout
« Reply #17 on: July 26, 2005, 08:16:15 AM »

Quote:


When running a LAB12 at 45VRMS, 40Hz, I found that it is not excursion limited, even in free air.  But it is extremely hot.  That leads me to believe that probably most failures are heat related, not excursion related. There will be lots of other horns there besides 12Pi horns and LABhorns.  Everyone is welcome, and I'm hoping to see and hear a variety of systems.  That's what we plan to do and you're welcome to join us if you wish.  The hornsub shootout isn't intended to polarize the market, it's intended to bring people together.


You cannot simply run a (espically a sub) speaker at a continous voltage and look at the parameters.  No doubt it will get hot.  But REAL music is full of LARGE transients that do not so much relate to a heating issue, but the excursion damage may be great.  This is not to say that heat is not an issue, but if that is your only concern, you might want to look at the real world performance.

Years ago I had a problem with my 2x18" "popping" when hit kinda of hard-put not strained.  I could run them with a pure signal to HIGH levels, but could never get them to get that loud with music.  I went through several dozen speakers, before changing to a different driver.  In this case it was not the cabinet (just a simple large ported design), as we tried them in various cabinets with the same results.  Other drivers did not have the same problem in my cabinets.

Real world is what you have to be concerned with, not putting all your eggs in one basket so to speak.  Heat is only 1 of the issues.
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Wayne Parham

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Re: Hornsub shootout
« Reply #18 on: July 26, 2005, 01:18:23 PM »


"Real world" measurements are the purpose of the hornsub shootout.  It will be a good place to get a bunch of systems together and see how they do.

As for the heat/excursion issue, I believe the data is pretty clear.  You described a speaker that probably was excursion limited.  I don't think this one is, and I base it on what I've measured and what Tamas has measured.  But as you say, it will be good to see how they all stack up in a real-world environment.  I'm hoping to have a few there to compare and contrast.

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Elliot Thompson

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Re: Hornsub shootout
« Reply #19 on: July 28, 2005, 04:11:12 AM »

Hey Wayne.

I would strongly suggest you keep in contact with David Lee &
Mark Seaton on your project.

These guys have been in basically, every sub shootout held
in the States, and, can give you ideas on things you might
of forgotten.

While the Subwoofer Shootout in NY had the right equipment
to perform the measurements, and, a wide variety of speakers,
we were very limited on music CDs.

I guess we all basically got caught up on the technical
side of things, and, forgot about the bottomline....
The music.

Seeing that you will have guys passing through from
all walks of life, different styles of music will play
a factor on how each sub compete head to head in the
ears of the listners.  

Another thing is amplifier power. I know your in the
early stage, but I'm curious what kind of power will
you have at your diposal to test these subs.

If David Lee is there, more than likely, two QSC PL
9.0s will be present representing his Bassmaxx.

Mark Seaton has already stated he has a TEF available
so, that will basically close the deal on precise
measurements.

However, if these gentlemen won't be available, for the
scheduled date, what do you have that will supply the
subs with the right amount of juice, and, take the
proper measurements in the open field?

Try contacting Paul Bell http://www.pbellsound.com/start.html
and Too Tall since they've already experienced what
goes on when conducting a Subwoofer Shootout.

Best Regards,

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Elliot
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