Tizman
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Posts posted by Tizman
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Just a quick question about installing the 15C in a La Scala or FH1. When installing, did you replace the gasket that came with the 15C? The way that the 15C is installed in a La Scala or a FH1 is against its front face. While the 15C has a nice gasket that will seal it nicely if it is mounted on the outside of a cabinet, the front gasket that is used is cut out around the screw holes, and looks like it could easily leak air. I ask because I have installed a pair in FH1s, and my measurements with REW show a large drop starting at 75 Hz or so as compared to a stock La Scala bin. The measured drop is also obvious when listening. I know that the 15C gives up a few HZ in extension compared to a K-33, but this is a lot more than a few HZ. Could this be an issue with my installed 15Cs leaking air around the gasket?
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On 10/27/2020 at 8:07 PM, geoff. said:
Thanks Geoff.
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9 hours ago, Chris A said:
Here is the same spectrogram plot for a tri-amped La Scala II using a Xilica XP4080, and completely dialed in
Thanks Chris. I think that I can use delay on the midrange and tweeter relative to the Incoming signal feeding the bass bin to get all three in alignment. -
Hi All. This is a great thread that has been very informative and helpful. I do have a question that I don't think was covered so far. I have a 2 in/4 out electronic crossover, the XTA DP200 and would like to use it as a crossover for the tweeter and mid-range horns in a La Scala that will allow me to time align them. My plan is to run the bass horn through its stock passive crossover (AL-3) and then use the XTA DP200 to feed the tweeter and mid-range. Is this not preferable to using the DP200 to split the signal between LF and MF/HF and using the passive to split the frequencies going to the mid-range horn and tweeter? Any thoughts and input you all may have would be most appreciated.
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On 2/1/2020 at 2:12 PM, Chris A said:
To not have deep bass nulls in the room requires a double bass array. To minimize the nulls requires at least two subwoofers (three are better). [I use three subwoofers (effectively) in my room, two on the opposite front corners of the room, and one in the center (actually it's the K-402-MEH, but it has -3 dB response at 16 Hz).]
Chris uses 3 subs in his setup, and says that this minimizes nulls. While this may not get the job done entirely, perhaps this combined with aggressive bass trapping may be the best practical solution.
5 hours ago, Edgar said:I've been aware of DBAs since I read the same AVS Forum posting that Chris mentioned. I've never seen or heard one in action.
Has anyone successfully applied the DBA setup? It would appear, based on Chris's quote above, that he does not use DBA in his setup. If I am reading Chris's quote correctly, he is using the equivalent of three subs along the front wall and not a DBA, and that this is sufficient for his setup.
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3 hours ago, Edgar said:
As such, the type of generator (i.e. horn or direct radiator) of the waves is almost irrelevant -- the propagation characteristics and standing wave pattern are controlled by the geometry of the room.
Thanks for the clarification. It would appear that the solution is room treatments or a DBA. On ChrisA’s suggestion, I read up on DBAs. My concern with them, based on my reading, is that there will be so much stuff in the room that will interfere with the operation of a DBA that it may not work properly. This is based on what I read, as I have no real world experience with them. Perhaps a DBA would work out to be the best real world solution.. It certainly appears to be the lease intrusive and most elegant solution.
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13 hours ago, Chris A said:
If you want to wash out the effects of room modes in a home-sized listening room, there is something called a "double bass array" (DBA)
Thanks for the reference Chris. I'm not sure how effective I can make it given that the room will contain 60 people or so, and the furniture required to seat these people, in addition to a lot of other stuff. I may have to make do with a very large bass absorber on the back wall, even though the DBA would be an elegant and far less intrusive solution. 60 people would also make for a pretty good bass absorber. A very inconsistent one though....
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9 hours ago, WMcD said:
I believe that a horn with output at 20 Hz has not been built, ever. If it were it would be larger than a house.
Yes. A proper straight 20 HZ horn is house size. If I understand this correctly, and I may not, lots of horns have output at 20 HZ, but do not control directivity at that frequency. Given my ceiling height of 10 feet/3 meters as a limitation, I can build a horn where directivity is controlled to about 57 HZ in the vertical. Horizontally, I can build a horn where directivity is controlled to around 19 HZ. Either way, there will be lots of output at 20HZ.
11 hours ago, Chris A said:I'd also recommend using something like four TH-SPUD designs on the front wall, and another four TH-SPUDs on the rear wall--wired out of phase from the front wall phase. It would take up much less space and be much easier to build. That would require 16 Tang Band 8" woofers (W8-740Ps) at about $100 each woofer to fully populate those SPUDs.
I understand that there may be better ways to do this, and thanks ChrisA for your suggestion that I look at DBA and the SPUDS. I will do so.
My goal here is to get the best sound possible in this room, and have it all be horn loaded. This project will prioritize SQ above any other criteria. There will be extensive acoustic treatments used in the room. For example, if I need to take up 10’ at the other end of the room for bass traps, it will be done. The goal is to have as large a sweet spot as possible, with the best SQ possible. All other criteria are far less important. -
I always thought that anything other than a full size horn was a compromise, with the various negatives associated to this compromise. My understanding is that the only reason that full size horns are not built is because they are too big for most situations, not because they are not the best way to go SQ wise. I am in the unusual situation of being able to build a full size horn. Or two if that will give a better result. I feel that this is a good thing.
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I might have to fold it though. Darn.
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On the smallish side, but that’s the idea.
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6 hours ago, Chris A said:
Could you elaborate why you feel that directivity is required below 100 Hz in a home-sized listening room?
I don’t think that this is the case. What I am trying to figure out is if having horn subwoofers that have directivity at these lower frequencies changes any requirements for the setup of my room. Specifically, will using a horn subwoofer with directivity down to 20HZ allow for a setup that uses one such horn instead of two. How will room modes be affected by using one as opposed to two? In a general sense, how does a horn subwoofer that is directional to 20HZ and whose mouth is flush with the front wall behave differently with respect to room modes as compared to a regular direct radiator sub?
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ChrisA and WMcD: Thank you very much for your replies.
In my drawing, I show the wall at the bottom creating a room of 8' X 30'. This was for the purpose of showing a specific example. However, this room is not built yet, and I do have a clean 30' X 50' room to work with. I can put the horn entirely behind this wall, or fold the horn somewhat so it fits in the corner. Either way, I can have the mouth come out at the boundary, rather than at some point beyond the boundary, in order to avoid back wall cancellations as referred to by ChrisA....
5 hours ago, Chris A said:If you place a very long/straight horn subwoofer in an enclosed space, the problem is that it is difficult to get the horn's mouth close enough to a room boundary to not have boundary gain "suck outs".
4 hours ago, Chris A said:So directivity is not really a factor in placement of subwoofers in rooms where all subwoofers--including horn-loaded ones of a mouth size that's less than a metre in minimum dimensions immediately lose directivity below ~170 Hz.
1 meter is roughly a half wavelength of 170 HZ. The horn mouth that I can use in this room can be as much as 3 meters high, by whatever width I choose. If I make it also 3 meters wide, the half wavelength is around 57 HZ for both width and height. 57 HZ not a subwoofer frequency, but if this system was high-passed with a steep filter at 57 HZ, what would the result be with respect to room modes? Would a single horn subwoofer placed in the middle pose more problems than one in each corner with respect to room modes? I could also I make the horn mouth 3 meters high by 5 meters wide, for example, if that helps the improve the directivity at a lower frequency. 3 meters is 57 HZ and 5 meters is 34 HZ half wavelength respectively.
3 hours ago, WMcD said:The lower the freq you want, the larger the mouth.
And I don't know how this will work out in your room. You can't avoid standing waves caused by reflections from the opposite wall even if you can keep sound off the wall behind the speaker.
I can make a very big mouth for this horn. If I use a single horn in the middle of the room, as in example "B", it can be 30' wide as in example "C". 30' is roughly 9 meters, which corresponds to 19 HZ half wavelength.
Attached is another drawing that takes into account the responses of Chris A and WMcD. In these drawings, assume the use of horn mouths that are a minimum of 3 meters in height and width. Example "C" uses the entire width of the room for the horn mouth, and the entire height, but could use a smaller portion of the width if that will result in a better outcome. "C" might seem crazy, but it is in fact entirely doable. Once again, your comments and insight are much appreciated.
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Hi All.
In my research on building a pair of subwoofers for an upcoming project, I have come across conflicting opinions on the impact that the type of subwoofers used have on room modes. Basically, some have said that because horn loaded subs are directional, room modes are less of an issue than they would be in the case of omni-directional direct radiator subs. My intention was originally to build a pair of straight 30HZ horns to combine with a pair of Jubilee speakers. My plan then went to using a single 30HZ sub. This was based on opinions that two horns would be serious overkill, and that the directional nature of the bass from a 30HZ horn would minimize issues with room modes and subwoofer placement as long as the horn was pointed at the listening area. I have read some of the literature that relates to subwoofer placement in rooms, and much of it recommends two or more subs placed using various strategies, but everything I have found relates to normal subwoofers, not 20 foot long horn subs with 50 square foot mouths. So what is the deal with the directional nature of straight horn subwoofers and room modes? I have attached a rough drawing of the room and three possible setups. The drawing is rough, but in each scenario the Jubilees are placed in the same position, and the subs in the corners, or in the middle as indicated. As always, your input is much appreciated! Cheers, Tiz.
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3 hours ago, Chris A said:
For your application, you haven't stated what kind of subwoofers you're considering, or whether the music that you play doesn't require response below 40 Hz.
Music will be very varied, with some material that includes low frequency synthesized bass (albeit not that much of it). The subwoofer will be a very large 30HZ horn loaded sub that will be as straight as possible (possibly with one fold or 90 degree turn). I am working on a design for that sub. It is very much a work in progress, but my most recent modelling is for a horn 6 Meters long with a mouth of 4.5 square meters. Thus my previous question with regard to using La Scala bins instead of Jubilees. Since the deep bass will be covered by this large horn, what am I gaining by using Jubilee bins over La Scala bins from a polars and dispersion perspective?
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5 minutes ago, Marvel said:
University Classics
Nice looking bins. What sort of HF driver is that on top of them?
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1 minute ago, Marvel said:
If you were to build your own MWM bins like DTEL, they can be downright pretty. I think he used red oak plywood.
Wow. Those are pretty.
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Also, just for clarity, if I use a La Scala bass bin and the K-402 (with a very large bass horn for the bottom end) crossed over at a frequency appropriate for the La Scalas (100HZ or so?), what am I losing relative to using a Jubilee bass bin crossed over at a lower frequency?
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20 minutes ago, Chris A said:
If you weren't listening in a head-in-a-vise style, they really weren't very enticing to listen to.
For the application I have, having a huge sweet spot is crucial, as the listening position should include the whole room. Thanks for helping me hone this to something I can move forward on. I have a quality two way crossover, but will need a quality three way for this system. Any recommendations?
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21 minutes ago, Chris A said:
Also note that a bass bin nose extension may be mitigated (Jubilee or MWM bass bins) if you do one thing: lower the K-402 horn by about 10 inches and allow it to stick out in front of the bass bin front panel, then use lower order crossover filters between the K-402 compression driver to fill in the polar lobing at the crossover frequency. This little trick was something that became much clearer when doing the K-402-MEH crossover. It works well to fill in the frontal lobe size around 300-500 Hz. It also significantly reduces the phase growth through the crossover region, and that made a huge difference in sound quality in my listening room.
Chris
Thanks for reminding me. I have seen you mention this in other threads. I will be using a three way electronic crossover on this project, and will be using a single, very large, 30HZ horn between the two two-ways. The crossover will include the delays needed to place the K402 where it is required, and to adjust the large bass horn's delay as well. If I do what you suggest above, will that for all intents and purposes effectively mitigate the issue with the dual mouths of the Jubilee bass bin? For the 1% of the 1%?
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40 minutes ago, Chris A said:
I'd make the K-402s into K-402-MEHs so that you can easily get the crossover frequency with the bass bin down below 200 Hz.
I have followed your work on this approach with much interest. The issue that I have with it is that it requires extensive modification of the K402. It would be myself doing it and, frankly, I am worried that I will mess it up.
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38 minutes ago, Chris A said:
2) Jub bass bins without nose extensions
It would seem that this is my best choice if I am going to purchase a product that doesn't require modification.
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29 minutes ago, Chris A said:
MWMs will win since they can be had for almost nothing
I'm in Toronto, Canada. I have never seem one available used since I started looking about a year ago, at any price. If there are any members that have a pair for sale (or know of a pair) within reasonable driving distance of Toronto, please let me know.
18 minutes ago, babadono said:Thought they was unobtanium.
I believe they can be purchased from your local Klipsch Pro dealer.
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I could be convinced into MWMs. They do cost a bit less than the Jubilee bins. I'll have to consult with the boss. A couple of photos courtesy of Coytee...
Are there any differences other than low end extension?
Replacing K-500 horn with K-510 ebay horn
in Technical/Restorations
Posted
Ebay 510s?
Never mind, I found tem.