Bass horn ideas again. A possible build. Need criticism.

[jwc]

I didn't bump this thread to get it started up again. I just needed to update it with my Frequency response Curve of my Jubilee Clone with the K-31-E drivers.

Measured with a mic at 3 meters just a few inches off the ground. In a brick wall corner outside.

jc

[DrWho]

And here I thought you were hoping to start looking into new ideas...

[PrestonTom]

Yeah I am bumping an old thread.

I just went through the whole thing in one sitting. It gives a different view.

The project is fantastic! The quality of the woodworking, attention to all the details & the countless decisions are remarkable. My hats off to you.

However, I am confused about your final verdict. Ignoring the price differential, which woofers did you prefer or would recommend.

Pioneer 51F

or the

K31

There seemed to be some back & forth in your comments.

I will say the RTA measured on the inside (den) of the K31 looked very, very impressive, although the room contribution was evident when I compared it to the "outside" measure.

It is not clear that whether you made a measure of sensitivity, but you implied that you thought the overall output was unexpectedly low. Do you have fresher thoughts on this issue?

Anyhow, a very impressive job,

-Tom

[jwc]

Tom. I apologize. I got to where I felt funny about posting anymore about the DIY Jub.

The outside curve with the K31 shows the results w/o much coloration from room gain. I didn't due real SPL. Only relative. I guess I should have calibrated and posted I actually got to feeling funny about posting the curves after I hit this last one. I felt that the testing was complete.

I honestly don't think there was a deficit in the SPL compared to the real deal with the K31's loaded. Why would there be really. I used the same throat and the same Vb. There may be some variation in the path of the horn but I don't understand why there would be an SPL loss. The physical horn length is exactly 140cm.

You have to realize that I was comparing the output of the jubs with my dbbs. The HF would have to be less attenuated when mated to the dbbs vs the jub clone.

The Pioneer 51F's are a good deal and good match. They actually go a little lower and have a little more grundge than the K31's. They may not be quite as punchy though. I really don't know about there SPL head to head with the K31's. I had both the jubs playing with different woofers and had about the same output. Bottom line is that thePioneers work. Some confusion came when from an initial listening standpoint...... as there is one corner that is more bass friendly. But when swapping things around...the conclusions above hold.

I hope this helps.

jc

[Guest " "]

jwcullison

What, no dual 18" versions?

[Coytee]

I'm starting an uncalled for rumor, that he's hunting down some old EV 30" drivers...

[Guest " "]

Yeah, thats it, the ultimate, quad electro-voice 30" drivers.

[PrestonTom]

Thanks for your further thoughts. You are a cautious one in giving praise for your cabinets.

One thing I noticed in the thread (all 33 pages) is that at least in terms of the modelling (or at least what Mike was able to cobble together) was that the impact of a Pasive Radiator is not large (or at least in this proposed implementation). Perhaps the modelling choice was indequate, I am only guessing.

I raise the issue since one of the Jubilee prototypes (the real deal) did use a passive radiator. Given the effort that would go into the design (I get the impression that PRs in general need a bit of fiddling to get it right) and also the effort in terms of construction (and extra expense for the PR itself), I would think only a bigpay -off would warrant the extra effort. Perhaps Roy knew of a bigger gain than what was being "demonstrated" by the modelling.

Good Luck,

-Tom

[Deang]

JC, regarding my comments in the other thread, sorry about that -- I didn't mean for them to sound derogatory.

Tom's observations mirror mine. All of my plots are at work, so I'm going on memory here. In Roy's plots, as well as the one in JAES paper -- I think we see a speaker that's basically 107dB across most of its range, and this is with no room gain. We should be able to say that the Jubilee is effectively 3dB more sensitive than the Klipschorn, and that speaker should be quite a bit more sensitive than the DBB C. I wouldn't put too much stock in the tap settings, especially with that swamper in there -- in determing sensivity relationships between the top and bottom. Besides, that whole thing is very subjective. The only thing we really want to look at is the least efficient part of these systems -- the bottoms. Simply put, we know a Jubilee is more efficient than a Klipschorn, and 'stacked cornwalls' should be 102dB. You have two woofers in parallel, which gives us 3dB in electric gain and 3dB in acoustic gain -- and I just don't see how you can be getting more than 102dB. Something just isn't adding up here.

[jwc]

I have a 12 inch passive radiator here. I ditched the idea of putting it between the two drivers as I am confused on what to due with the total slot area/throat. Tuning it I could have eventually figured out.

You see.....2 12 active drivers with a 45 sq in throat for a total of 90 sq in. The horn is designed around that throat size in the AES article.

No if I were to put the 12 passive between the two actives.....I would have to decide on how to flare the middle passive and what would be the slot cutout for the three. I would assume that the entire horn would still need to be based oj a 90 sq in total throat.

There are several things I could try. Just do 3 different slots of 5 X 9 and make the flares all equal. I would assume the passive's throat would add to the actives and then the total throat would be 135 sq in.

Or I could reduce the slot of all three down to 5 X 6 and make the flares accordingly. Total throat 90 sq in?

Or keep the active throats at 45 sq in a peice and just do the passive in the middle with a rubber throat.

Or rubber throat all of them.

To be honest, I can build a jubilee in about 2 weeks with my work schedule. I could throw one of these together but you see how experimentation with several different options become lengthy and expensive.

The most simple option I thought of was to build the jub just as I have it and have a port at the bottom cover. Not a passive but say two 4" tubular ports. They would fire down onto a 45 degree reflector that went into an expanding horn that would be like a base that the entire cabinet would sit on. If it didn't work...then you didn't destroy the jubilee. Guys with the real deal could try this as well.

There are other options such as porting right out the front in that middle dead space. The port wouldn't be in the horn but you would still have the benifits of the porting.

Man this thread is getting dug up again and my mind just went through all those drawings I did. At some point I will re-explore the jub clone. I already have the small jub for a center drawn up. I just need the time. SpeakF...I may just need to send the mini jub plans to you. Right now I am trying to finish up the Jamboree project and I already have started the initial woodwork on the 225hz Edgar style midhorn for a 2" compression driver.

jc

[jwc]

Dean. I didn't take anything as derogatory.

I can't tell you the exact SPL. I didn't realize that was a concerning point until now. Otherwise I would have proved it with calibration of my RTA. I just didn't feel like doing that all over again.

I wish someone would have challenged me on it and forced me to look into it. The key to this thread "NEED CRITICISM". You used to "knock me around a little" and it always helped me look further into finding out the answer. My personality on this forum is to come across as a little bit of an idiot or gutsy and that would typically invite all kinds of criricism. I found it as getting the info I needed. I guess now that I've been here awhile....maybe that won't work anymore.

Unfortunately..as you know....the jub clones are no longer in my hands. I was keeping quiet about it but now with this SPL question arising, I have to explain why I can't prove it any further. They are now in the hands of someone who got the deal of the century. It would make you sick to know how much I sold them for. I just had to clear out my basement. Other stuff was sold as well.

I have heard the jubs in hope and at Richard's house. The ones I made sounded just like what I had heard before. I really didn't question it.

There are a lot of other things that I could go through to support my feeling of the SPL deal.......but it would be my opinion. Subjective.....that always sucks really.

O well. There gone and I can't do anymore testing on them. I wish i was aware of this doubt and I would have explored more. Maybe I will on the next set.

If someone tries to make the arguement that I sold them because they sucked...that isn't so. Besides...I sold them to a buddy and I would never do something like that.

I still struggle with this whole bass horn concept and I am making the best attempt I can to convince me that a bass horn is the way to go. I have no reason to make up some bull but I honestly can't get a result that surpasses the sound of my dbbs to my likeing. I don't spit this out much as it opens up wars...I'm not a Khorn/jubilee basher or PWK basher or a Roy basher. I have a lot of respect there. My ears just aren't telling me that that the bass coming out of these things is what I am wanting in the end. I'm afraid that I listened to too much funk over the years in my sooped up car stereo with those big subs. I somehow think I like crude bass and that is my problem I guess.

I am moving into a new house in a couple of years and I am trying to solidify what I want. I look at the Cinema products by klipsch and I would bet bottom dollar that I would like the bass reflex bass bin with the 4 15" drivers more than say I would the Jubilee. I don't know....I am rambling now. I've been beating myself up alot lately as I always thought of someone who has golden ears for great audio but I can't seem to have the same liking as the majority of folks on this forum.

Well anyway. Dean......I hope you find the jubilees to be super dooper man. I will jump into them again later myself. I may even talk one of my local buddies to buy some as he is building this rediculous outdoor entertainment area with a pool.

jc

[DrWho]

Hey JC, we're in the same boat....I too am an extremely huge fan of PWK, Roy, and all the coolness of horns, but I'm still waiting for my ears to agree. The engineering side of me wants to quanitfy the difference and then integrate it into a new horn design, but that's way beyond me right now. I must confess being a little jealous of your capacity to whip through all these designs [Y]

I think it important to note though that any unsatisfaction stems from these bass horns being among the "best" speakers available and I find myself wanting thee "best option available" to be "perfect", which sadly will never be the case. But alas, is that not the goal?

Since we're on the topic and you've had a lot of time to compare for yourself in your own home...Do you think low frequency extension has anything to do with your perceptions? A thought that has crossed my mind is that because the horn is a "high pass filter", any low freqeuncy material that the driver would have played isn't going to be amplified - however, all of the harmonic distortions associated with that note will be amplified - further increasing their magnitude relative to the fundamental note. So what you end up with are distorted low notes without any essence of the fundamental....whereas on a direct radiator system, you still have the same distortion levels (maybe even more), but the fundamental note is more prominent. I think this would be consistent with a lot of the impressions on the forum as well since it will only show itself when the source material calls upon the lower notes. To test that theory I've been wanting to listen to a 25Hz hornloaded bass bin. Yea, I know it'd be huge and very difficult to achieve useful high frequency extension.

[Guest " "]

"SpeakF...I may just need to send the mini jub plans to you."

You send it - I'll build it.

Mini-jubs will work for me due to room sizes and the fact that I expect to use an active sub-woofer.   Thinking that a smaller version can be blalanced between size and cut-off points between the mini-jub and the active sub-woofer.

 

[jwc]

Mike I hear ya. More on that later.

Speak F.-let me see if I can get this together in a reasonable fashion. If memory serves, the bass bin is 25 inches internal height, 1/8 space corner horn, about 31" wide, shaped like jub, Fc cutoff 70Hz. Exit physical mouth isn't cut short.....IOW....the exit is the full mouth for an Fc of 70 Hz.

[Guest " "]

Mike I hear ya.  More on that later.

 

Speak F.-let me see if I can get this together in a reasonable fashion.  If memory serves, the bass bin is 25 inches internal height, 1/8 space corner horn, about 31" wide, shaped like jub, Fc cutoff 70Hz.  Exit physical mouth isn't cut short.....IOW....the exit is the full mouth for an Fc of 70 Hz.

I'm really curious about compressing the width somehow, maybe by using smaller drivers with deeper excursion's and could probally tollerate something that was taller than it's width rather than wider than it's height. 

It wouldn't need to fill a concert hall so 1000 watt power handling with a 121 spl upper ceiling wouldn't be a design consideration.

The jub type cabs seem to wind up with a width thats three times the size of the driver used.  So I need to think small driver with deep excursion to get smaller footprints.  12=36, 10=30, 8=24, 6=18, etc.  

If used with a sub, 70hz would be fine,  But some how I'm thinking there's a missing element in the forcasting realm if a mini-jub forcasts the same low frequency that a Hersey does.

I understand the concept of horns being hi-pass filters, so the key is to balance with a decent lo-pass device(s), active sub, tuned port, radiator, etc.  Since the passsive approach is only good for half an octave, going active seems like the best choice.

But, you know, there has been much comparison to direct radiators.  Direct radiators have come a long way, and the price to performance ratio is impressive.  40 years ago it was costly to put 2 woofers in one cab, today Klipsch has a small footprint box with 3 woofers in it.  Point is maybe as you get smaller if you increase the driver count, the SPL level will be reasonable.  On the extreme end, if small foot print was a design goal, you could combine the Jub and the Jam and stick eight eight inch drivers in there (2 facing colums of 4 veritcal) and still only be at 32 high by 24 wide.

 

[Guest " "]

Mike I hear ya.  More on that later.

 

Speak F.-let me see if I can get this together in a reasonable fashion.  If memory serves, the bass bin is 25 inches internal height, 1/8 space corner horn, about 31" wide, shaped like jub, Fc cutoff 70Hz.  Exit physical mouth isn't cut short.....IOW....the exit is the full mouth for an Fc of 70 Hz.

I'm really curious about compressing the width somehow, maybe by using smaller drivers with deeper excursion's and could probally tollerate something that was taller than it's width rather than wider than it's height. 

It wouldn't need to fill a concert hall so 1000 watt power handling with a 121 spl upper ceiling wouldn't be a design consideration.

The jub type cabs seem to wind up with a width thats three times the size of the driver used.  So I need to think small driver with deep excursion to get smaller footprints.  12=36, 10=30, 8=24, 6=18, etc.  

If used with a sub, 70hz would be fine,  But some how I'm thinking there's a missing element in the forcasting realm if a mini-jub forcasts the same low frequency that a Hersey does.

I understand the concept of horns being hi-pass filters, so the key is to balance with a decent lo-pass device(s), active sub, tuned port, radiator, etc.  Since the passsive approach is only good for half an octave, going active seems like the best choice.

But, you know, there has been much comparison to direct radiators.  Direct radiators have come a long way, and the price to performance ratio is impressive.  40 years ago it was costly to put 2 woofers in one cab, today Klipsch has a small footprint box with 3 woofers in it.  Point is maybe as you get smaller if you increase the driver count, the SPL level will be reasonable.  On the extreme end, if small foot print was a design goal, you could combine the Jub and the Jam and stick eight eight inch drivers in there (2 facing colums of 4 veritcal) and still only be at 32 high by 24 wide.

 

[DrWho]

The size of a bass horn has nothing to do with the size of the drivers being used. If you wanted, you could put two 4" drivers in the Jubilee and achieve the same frequency response (with proper driver "selection"). The problem is that the cone excursion requirements increase while the efficiency also goes down, which opens the door to a whole slew of other issues. Nevertheless, the horn would need to be the same size to achieve the same frequency response.

For what it's worth - the Heresy has more low frequency extension than the lascala (which is also a 70Hz horn).

[Guest " "]

DrWho

I don't understand your question.

My last post has more to do with "art" than "science" , so the scientific approach may not apply. Simply a matter of putting the computer keyboard aside and taking the hammer and saw to some wood.

Simply put, I'm going to build a mini-jubilee and stuff it with drivers.

From what I have seen over the last year concerning forcasting and modeling, it's simply an effort to determine a starting point.

I have determined my starting point using the "water stick" method.

[jwc]

There are several ways to make a small version with different drivers. The one I have scetched up is designed for a 90 sq in throat with two 12 inch drivers. You could basically throw in the K31's and you would have a matching bass bin with the jubilees as surrrounds or a center. They could also stand alone as two ronts **** you would La Scalas. It would look good too.

Yes....Mike ...Like a La Scala but not a 1/4the space horm. However, the one I drew up is abou a 70Hz flare throughout unlike the scalas which has a 125Hz flare in there. You could flare "like" the Lascala with two 12" drivers and make the bass bin slightly taller and more narrow.

[jwc]

SPeak F...I'll get that plan to you. Not sendable right now.

jc