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  »  New  Romy The Cat's new Listening Room..  Won't be the last time he makes that trip!...  Audio Discussions  Forum     478  2779274  03-28-2010
  »  New  Midbass Horns and Real Estate...  Just a youtube video......  Horn-Loaded Speakers Forum     247  2062212  07-26-2009
09-20-2017 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,049
Joined on 05-28-2004

Post #: 201
Post ID: 23403
Reply to: 23402
Actually…
Since Anthony posted his post this morning I have been thinking about it. Ok, I have drivers, If I pile 10 of them then I will have 88.7+9X1.4 = 101.2dB sensitivity. This always is workable number more or less. I will get a lot of room gas with it. 5 enclosures by 22” each would make 110” high I do have this high. I am thinking about 3.5 foot deep boxes, so it will be 12x22x42 with two drivers mounted in there. I think I can find a builder who can do $100 per box that would make 1K for boxes and including finishing, binding, damping it will be under 2K a complete project . Not so pricy and it even might be elegant….   

The questions that I have is would it be enough for my room? Then, what would it do with my 60dB room mode. Those large arrays with cylindrical waves do very good with room problem but there is absolutely no way to tell anything until I have the monster in the room.  Probably it would be good idea to pile up R and L sides together and to run it only with one channel, this will give me some idea if it might be enough… 
 
The idea to use 2-4 15” drivers with 100dB sensitivity to start with is a nice idea but any good drivers that I know and have some vintage Altecs and Vitovax are resonant type drivers that do not go very low. They are basically midbass drivers. For sure I can go for better JBLs but they we enter the ported world and I am not sure if I would like to step in that pile of shit again. 
 
Good, I miss my midbass horn….


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
09-20-2017 Post does not mapped to Knowledge Tree
anthony
Posts 335
Joined on 08-18-2014

Post #: 202
Post ID: 23404
Reply to: 23403
The Scanspeaks
In my experimenting here, not really listening mind you, it looks like you can get a very nice frequency response to about 150Hz with those Scanspeak woofers.  This frequency sits about where your Upperbass is rolling off so there is also the (distant) possibility that a new 10 driver array would be able to go all the way up to that point.  Whether that sounds good and is desirable I have no idea, but it is another possibility.  Here are my gated measurements of some different cabinet stuffing in my "Cannons"...

More HD and GS Batts.jpg

No smoothing on graph.


Gold = empty tube, no stuffing
Cyan = low density stuffing close to the rear of the driver
Magenta = high density glass fibre stuffing at far end of tube
Dark Blue = mix of high density glass fibre batts at the far end of the tube and low density behind the driver 

The measurements have been aligned at the 20Hz hump at the bottom of my microphone calibration, but you can see how the SPL can be changed with various amounts and types of damping...3dB difference at 150Hz may be something you may be able to work with.  The high density glass fibre batts in a longer box such as you are proposing can be used quite effectively to damp the reflected backwave and reduce driver output at all frequencies, especially higher frequencies.

How does it all sound?  I cannot tell you because I am not yet finished.
09-20-2017 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,049
Joined on 05-28-2004

Post #: 203
Post ID: 23405
Reply to: 23404
The Scanspeak woofers.
I would not advise to use my Scanspeak woofers all the way to 150Hz. For sure you can but I feel that they are fine in sub 100Hz. The upper bass need to have more HF resonance and the Scanspeak rubber surround is not best for it. For sure it is not regular rubber as it use in PA woofers. It is a very good non-inertia rubber that rather feels as fabric then rubber. Nevertheless it is not paper, fabric or leather and I would not climb very far in HF with those driver drivers. For sure you will have sonic output in there but you will also find many other drivers that would perform belter then the Scanspeak over 100Hz. 
 
Your diagram of the SPL change with different type of damping is very interesting, thank you for sharing. It is also very much what I suspected. I care less what is going on over 30Hz but the left side of the diagram is very nice indeed. 
 
Anthony, one more very important tip I would like to give to you. Churchill (is I am not mistaken) once said that if you want to confuse people then give them facts. The point was that facts do not clear anything, the important are not the facts themselves but the patterns of the facts and the interpretation of the facts meaning. It took for mean a few years to understand how to measure loudspeakers. You need to measure them AND to listen them. If you have any minute mis-synchronization of auditable and measurable then you do not measure the right things. It is not always so simple, in fact it might be very complex and at time you will be find yourself that what you feel conflict with what you objectively witness.  It sometimes take a long thinking on the problem and many experiment but you MUST find a harmony between what you hear and what you understand as a measurements. If you do then you will perceive measurements very differently, I promise you. The measurements will be not an indicator of you playback response but a reflection of your experience and it will be a very different category.


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
09-20-2017 Post does not mapped to Knowledge Tree
anthony
Posts 335
Joined on 08-18-2014

Post #: 204
Post ID: 23406
Reply to: 23405
Ah, Winnie...
 Romy the Cat wrote:

Anthony, one more very important tip I would like to give to you. Churchill (is I am not mistaken) once said that if you want to confuse people then give them facts. The point was that facts do not clear anything, the important are not the facts themselves but the patterns of the facts and the interpretation of the facts meaning. It took for mean a few years to understand how to measure loudspeakers. You need to measure them AND to listen them. If you have any minute mis-synchronization of auditable and measurable then you do not measure the right things. It is not always so simple, in fact it might be very complex and at time you will be find yourself that what you feel conflict with what you objectively witness.  It sometimes take a long thinking on the problem and many experiment but you MUST find a harmony between what you hear and what you understand as a measurements. If you do then you will perceive measurements very differently, I promise you. The measurements will be not an indicator of you playback response but a reflection of your experience and it will be a very different category.


...I've been reading quite a bit of Churchill lately...the political parallels between now and the time between the World Wars are quite disturbing.

There is no need to worry about my relationship to measurements...I feel that you and I are on a similar page.  I have an Applied Science Degree that is basically all about making measurements of physical things so I have had many years to think about what "measurements" actually mean and how they should actually be used, as opposed to how they are often used.  They are very useful if you are able to accurately measure the right things and most importantly if you have good insight into the subject at hand, but if you use them as the sole metrics for success then that project is unlikely to be as successful as it possibly could be regardless of if you are building speakers or breeding livestock or something else. 


09-20-2017 Post does not mapped to Knowledge Tree
noviygera


Chicago, IL
Posts 177
Joined on 06-12-2009

Post #: 205
Post ID: 23407
Reply to: 23405
Last version
Romy,What was the reason you were not happy with the last version of your midbass section? THe one with two Vitavox 15" per side. 
09-21-2017 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,049
Joined on 05-28-2004

Post #: 206
Post ID: 23408
Reply to: 23407
I wrote about it.
 noviygera wrote:
Romy,What was the reason you were not happy with the last version of your midbass section? THe one with two Vitavox 15" per side. 
It was not a last version but rather a temporary test version. I used in undersized sealed boxes the drivers that meant to be used for a completely different application. Anyhow, as I written above I do have a very reputes upper bass with them but anything below I would say 60-70Hz is sub-acceptable. 


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
09-21-2017 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,570
Joined on 10-12-2006

Post #: 207
Post ID: 23409
Reply to: 23408
Layout
Romy, is there any way you can re-arrange tor re-configure the speakers in order to accommodate the stacked 15" drivers, or are you determined to push your speakers against the wall where they are now?  I ask because I have heard stacked 15" drivers in a larger space than yours making integrated bass, albeit they were driven by SS, and I did not take that into account at the time.  Yes, I realize that there are many elements in play here.  And I am not saying you can push the bass drivers to do ULF, as well.  But you should be able to get them below 40 Hz, anyway, without compromising bass structure and tonality.  I have also heard small-ish, self-powered speakers doing ULF, this being largely a matter of room placement and contouring, so maybe you don't need to spend a lot of real estate on that?  I am not selling my SS amps for your purposes, but it did not take me all that long to find them for my own purposes.  And, as we have discussed plenty before, there seem to be plenty of choices for ULF amps.

Best regards,
Paul S
09-24-2017 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,049
Joined on 05-28-2004

Post #: 208
Post ID: 23413
Reply to: 22459
Kind of LF depression…
The kids are growing up and twins sleep fine and walk already. So, the Bessnow’s household is calming down, a live-in nanny for sure helps… With more time at my heads I am trying to finalize my playback in our new home. I spent a few hours today to experiment with different lower octaves solution for Macondo. There is something better and something worse but frankly none of the solutions, looking the result I am getting, not worthy from my point of view. I mean I can make it to work but it all is a stretch and just a substitute of my desire to return my playback to the day of former glory.  None of the solution that I have are neither good sonically or elegant technically, not to mention inspiring as a “last solution”. 
   
Her are just a brief overview of my thoughts, juts to organize them for myself.  
 
Here is the Left channel response with no bass of any kind. It is RTA 48 measurements per octave. The microphone is approximately 30 inches closer then I presume the sweet spot should be.  The MF/FH a bit attenuated compare to upper bass and the microphone extended further from the horns axis. I have done it intentionally to see the upper bass output more prominently. The resolution is quite high 2dB per square and the entire sweep is from 10Hz to 2kHz. 
 


The channel does somewhere what is expected. The 50Hz large peak I am sure coming from the corners the left channel located.  I was moving the speakers and was changing the position but it is still there. It would be necessary to play with the lowers channels to mask it out. The most typical solution from the way how I deal with the problems like this (means do not fight with room but design channels to fit the idiosyncrasies of the room)  is it to make one channel from 125Hz to 60Hz and another from 40Hz and all the way down. The problem then how to drive the damn sub 40Hz section. The Milq will not do it unless it will be over 100dB sensitive. So, just based upon the sweep below the design of the LF solution organically flows: 60-125Hz a tandem of vintage woofers and then LF section. For the LF section would do an array of 10 of my beloved pimpled Scans Speak drivers. For 60-125Hz will do pretty much anything. It might be sealed solution of something similar to Altec 815A. How to position 10 drivers array and a tandem of 15” woofers in time aligned position is bit dilemma but addressable I think.  The advantage of this solution that I can very prissily to factor the crossover for midbass and lower bass to fit the profile of each channel.  Take a look at the right channels it is slightly different.  


It is the room gain and is and at 100Hz. So, I might plays with flooding or phase tuning the midbass in a different way than the left channels and it might work. What this solution lacks of elegance and there is something else. The room responses to my current Macondo and it might or might not be the response to 100 inch tall LF line array. It is very difficult, if ever possible to predict what will happen after I put a huge amount of boxes in the room. I can model it to degree using juts one sub 40Hz unit and drive it with a powerful SS but it will not be the same. So, there is no way to say how the sub 40Hz array will behave until you built the damn things and put it into THIS room. Now very promising… 
 
Anyhow, here is the response of Macondo complimented by a pair of 15” Vitovoxes in small and shitty sealed boxes. It is very nicely cover the desired region but it drops like a rock. I think with larger, let say 6-8 cube feet per driver, enclosure and  a proper damping it might have a slightly smother decay. Something that I would very much need, regardless how much it will be supported by next LF channel. I would like to have in there 12dB decay and I might not get it with Vitovoxes.  
 


Here is the Macondo Right Chennal supported from the bottom my Scans Speak 72” line array, 4 drivers. I brought it just for illustration. If discard the 50Hz peaks then we are good 6-10 dB lower in amplitude of to cross at sub 40Hz.



The last one is my Left Channels with a single Klipsch corner horn crossed at 115Hz with default K30 driver.  When I first connected it I hated it and now I play with it a bit and I like it more.  I lost the time-alignment which is unpleasant. I can make the Klipsch horns to sound much better: better driver, better crossover dialing, better corner loading… it is a bit stiff solution but it does decay nicely in the room. In fact it decays too long, that 12Hz peaks is a bitch and it is very auditable. I need to play with corner loading to get rid of it I guess…





"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
09-24-2017 Post does not mapped to Knowledge Tree
anthony
Posts 335
Joined on 08-18-2014

Post #: 209
Post ID: 23414
Reply to: 23413
The one that got away
Hi Romy,

The first graph is the Right Channel (not the left as stated - therefore it is identical to the second graph) and the graph with the Scanspeaks is missing.  I'm interested to see what you have measured.

Regards,

Anthony
09-24-2017 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,049
Joined on 05-28-2004

Post #: 210
Post ID: 23415
Reply to: 23414
Updated.
Juts updated the images, thanks for letting me know. You might want to drop the browser cache for my site to see the refreshed images...


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
09-25-2017 Post does not mapped to Knowledge Tree
martinshorn
Germany
Posts 114
Joined on 04-14-2017

Post #: 211
Post ID: 23416
Reply to: 23415
Respect!
Wow, Romy, respect. For an analogue 5-6 way in room response... that's amazing! Esp. mid-highs. Id never guess.

I can imagine that khorn graph sounds difficult. Wouldn't blame the horn for that, rather the room modes.
The 75 cycle suckout likely resonates very long after, guess u can hear the tale after the impulse. I guess there must be an alisson effect around your seat of 3-4 feet (?)
But if you were 3-4 feet away from the chair its difficult to say, as the suckout could vanish if u move the mike.

Its also 3-4 dB too loud and the 45 cycle resonance of the K33 is boosted a lot. As you say, different driver and should be better.


But, you didn't replace the K151 but extended or theyre completely out??
I was wondering why u cross the K's so low.
On the other hand maybe new driver and corner load optimization should be first in place, then I love the sound around the 200 cycle region from the K's more than any other in the world Smile


Edit: I see the suckout is gone when using the scanspeaks. Could be from the sealing maybe ?? In case u use large cylinder wave its gone. Stacking 2 Ks would do the same.
09-25-2017 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,049
Joined on 05-28-2004

Post #: 212
Post ID: 23418
Reply to: 23416
There are plenty things to think about.

 martinshorn wrote:
The 75 cycle suckout likely resonates very long after, guess u can hear the tale after the impulse. I guess there must be an alisson effect around your seat of 3-4 feet (?) 

I was wondering about the 75Hz suckout, it should not be there but I would not worry about it. The K-horn is not mounted correctly in corner, we just throw it to the corner as is. The corner has baseboard that I did not remove and the K-horn has baseboard whole which is twice larger then my actual baseboard. If I keep the K-horn then I will change the back panel to assure a perfect corner fitting. Also. The K-horn has no top panel, so it is not really a finished experiment. I do not particularly feel comfortable about using impulse under 150-200Hz. To get there you need to use Fourier transform analysis to filter out room reflection and I always feel uncomfortable with interpreting it.  You can get very wide window, filter out the room and make the perfect timing but it will not always be the same as the max summing gain from 3 sources: 2 matching channels and the room. I personally prefer always include the room and I do not fill that FFT is practical at LF.

 martinshorn wrote:
I was wondering why u cross the K's so low. On the other hand maybe new driver and corner load optimization should be first in place, then I love the sound around the 200 cycle region from the K's more than any other in the world 
The K-horn runs with default woofer and if I want my Vitavox to be mount I need to pay for the K-horn and it requires to be made a custom backer that need to be glued in. The best upperbas that I heard in my life was from Vitavox corner horn, which is very much the same as the K-horn in bass section. So, I did not play too much with crossover, particularly as I have my uppoerbass horns that do just fine. The idea to cross it as low as I need was to minimize the frequencies that go time misaligned. But as I said, I need to experiment more with it.

 martinshorn wrote:
Edit: I see the suckout is gone when using the scanspeaks. Could be from the sealing maybe ?? In case u use large cylinder wave its gone. Stacking 2 Ks would do the same.

Well, the measurement with scanspeaks array is right channel, so it is less relevant.  I do not worry about the suckout too much and it is might be fixes later on. The bigger dilemma with K-horn is that it max unexpectedly low in that corner. If it was 70-80Hz or 25-30Hz then it would be workable but 40-50 is exactly where my room corner has large gain… Perhaps I need a smaller horn in that corner…


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
09-25-2017 Post does not mapped to Knowledge Tree
martinshorn
Germany
Posts 114
Joined on 04-14-2017

Post #: 213
Post ID: 23419
Reply to: 23418
Devil invented the room :)
Hi Romy
In my experiments, the corner loading influenced largely between 120 and 350. Above 350 u need a phaseplug on the cone.
Below 120 its pretty much immune to the details of corner loading, max a bit.
Below 50 its even sensitive to the wall material. Stone gives easily >10dB more gain than wood or gyprock/plasterboard in the sub-subs.

But.. for your response I think it sounds reasonable what u say, your room gains around 50. Coz the K's would normally decline below 90.
The K33 may increase this a little in addition.
But the 50 cycle gain should be easy to suck out with a soft negative peak in your SET input stage or?
I would rather worry bout the 70c whole. My burst decay analysis (eg T60) always proved that suckouts ring with tales of hundreds of miliseconds.
So as notches do.

I honestly beg you, ask a strong buddy to come over, lift the right K on top of the left, hook up both their cables serial, measure again.
That should look way better. Just as a test. I know listening in mono sucks. But if that wont lighten up a smile in your face, I owe u one! Smile
09-25-2017 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,049
Joined on 05-28-2004

Post #: 214
Post ID: 23420
Reply to: 23419
The way how I see it…
martinshorn, I do not pay too much attention to  K-hor as now as I do not pay too much attention to Midbass channel. If I do not go for big ass midbass horn with large moth that would change the whole room repose picture then to make a midbass channel that would do 70-140Hz is not very difficult. My biggest question not that if I decided to do it then what should I do with sub 40Hz channel. 40Hz is too high frequency to drive it with SS and it would need a lot of power that I do not have or a lot of sensitively that I do not have for my room. If I have a built array of 10 sunspeak drives and knew how they will response in the room then it would be much easier to predict. Recourse and efforts wise to build 2 large 107 “ toll arrays is the same as to build 40Hz midbass horn, conspiring the I have already the back chambers that I took off from the old house. So, I am not sure where to go at this point. If I go the large midbass horn that I might not have the 50Hz peaks as the mouth of the horn will be at very different size of room and will have very different geometry. I might then easy go for sub 25Hz 4x10 sunspeak with SS amplification… That is what I am debating…


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
09-26-2017 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,049
Joined on 05-28-2004

Post #: 215
Post ID: 23422
Reply to: 23413
A semi-temporary solution for now.
After a few agonizing days I think a have decided for a provisional solution.  Listening and thinking about options on a table and my current desire to invest time and resources I went with 6+2 direction.

 
I have order 4 separate relatively-small sealed boxes for Vitavox 15. They will be two per side midbass channels. I will not drive the Vitavoxes all the way down and will be cutting them most likely with second order at 60-70Hz at the bottom, so I can save some space on midbass enclosure and make instead the midbass time aligned. At the bottom, probably around 40Hz it will be an array of 6 sunspeaks. This trains never left the station… Bothe channels will be driver from Milq LF section and will use passive filtration. I do not think that 6 sunspeaks. Will be enough to deal with my current room but I am planning to live it for now. It will be listenable and will make the Vitavoxes to “decay slower”. The key would be to play with crossover separately for right and left channel to dial very accurately the room. I also would like to experiment a bit with what I call “distributed channel” where individual transduces will nave own enclosures and can play individual timing games. In a past I did play with lower MF channels this game and it was very powerful and it allow to spin a bit driver and to get slightly different phasing. I never did it with multiple midbasses but it should work the same +  I can located the individual midbasses incisures at different locations. Warn you that this is dirty trick and if very oppose the idea to do it as in my view a playbacks should strictly be time-aligned. What I would like to learn is the cost-benefit ratio from putting midbass in “distributed mis-alignment” vs having a non-resolvable extra 8-10dB in response. Let see how it goes… 
 
I kind a sick not to have a playback operational. The 6+2 solution with passive filtration will give some option to play it “for now” let see how I will feel about it with time. I do not need to make any big sacrifices to set it us as I have everything, so let put it in use and see what I will end up. I might add an extra 2 sunspeaks if I will be “almost there” or will go for new boxes with 10 sunspeaks that most likely will do the job. Let see how it drifts…


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
09-27-2017 Post does not mapped to Knowledge Tree
noviygera


Chicago, IL
Posts 177
Joined on 06-12-2009

Post #: 216
Post ID: 23423
Reply to: 23422
One more theoretical solution
These are 103db efficient 15" midbass boxes. It's a band pass horn design with narrow bandwidth of 60-250hz. No port thought, it's a sealed box with two chambers in front of the driver. I do not know how they sound but, myself interested in trying them out (perhaps to rent from the US distributor). It could be bad sounding but maybe not, since you do not need to cross very high:http://www.funktion-one.com/products/f115-mk2/
I can see a few good things about this design in the context of your system:1. Easy to time align because of the short horn is not really a horn. It's probably around 24" deep.2. Very efficient but has steep rolloff below the pass band.  The image below is is the 18" version, just to give an idea of the loading mechanism.

Although I did not have a great experience with the straight short Edgar horn, I feel these are not equivalent. I did hear a this design briefly and it sounded promising. By no means I am recommending this for you but it is theoretically a option, as a more efficient version of your Vitavox sealed boxes.
09-27-2017 Post does not mapped to Knowledge Tree
martinshorn
Germany
Posts 114
Joined on 04-14-2017

Post #: 217
Post ID: 23424
Reply to: 23423
Almost familiar
hehe following your advice loading the Vitavox into small horn... you'll slowly get like the Vox Olympian SmileNow some compromises for the usual domestic customer, and you can understand how Kevin got his concept in the first place 
10-01-2017 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,049
Joined on 05-28-2004

Post #: 218
Post ID: 23426
Reply to: 23422
This weekend
This weekend wife told me that I should not do nothing else but to fix my playback and this was exactly what I wanted to do. Yesterday I took good 14 hours to play with it, moving boxes, trying to find a good configuration, making measurements, thinking about results. I think I have fond a configuration that give to me more or less acceptable sound, actually to my surprise. The surprise did not come from the fact the sound is good, in fact I did not listen it critically but from the message that I got from all of it that my “small blood” solution can work.  If you do not build playback yourself and did not play with all of it then you might not be interested for the rest. I post it for the guys who experiment with it and for myself, to organize some of my thoughts and to keep sanity. 
 
So, I entered the fight with very well defined objectives. I do not want to use any powerful SS amp to drive my playback, I want just one Milq, one set of wires and one power switch. I want it to be more or less good enough to let me to hang (a few years?) until I go to my new midbass horn project. I would like to keep it as time-aligned as possible.  I would like to have more or less flat frequency response with individual channels decay very gradually and waterflow more or less consistent, with no large timing-frequency gaps. I would like to have first order filtration if possible. I would like it to sound if not good but acceptable. I would like do not spend more money, use whatever I have and to finish within 2 days.
Well, I spend all yesterday with my right channel, the one that has no corner and the more complex one.  Here is what I end up with. I use a single (not pair) Vitavox 15 driver in sealed box and midbass channel and line array of 6 pimpled Scanspeak as LF. I drive everything from Milq LF and … it kind of works. Here is the crossover I end up with, it most likely will be changing more.  

LF_Crossover.jpg


The response is not as smooth as I use to but all together it is not as bad as I the room response to the topology of the acoustic system I have. I have more of less consistent response down to 30Hz and then it decays very nicely with a good -4dB bump and 24Hz. The LF tower of 5.3R impedance is sitting at 45Hz lowpass. So, it doe the upper region being on low pass transition slope. The midbass channel with 15R impedance is sitting at 130Hz low pass to meet the upper bass horns. It is in a small 18x18x18 seals box and it drops at 50Hz like a rock. Generally it does not need to be high passed as the acoustic suspension of the small sealed box will hold the driver tightly but my concern was about the amp loading. It has not a typical for me over 10:1 output transformer but 5.3:1. It works very fine with my Scanspeak but at LF the Scanspeak begin to see the Vitavox and overall load to the amp drops and Milq might run in current hanger. It would be nice to have one more Milq channels but I do not have one. A consideration would be to have a nice SS follower after the Milq LF transformer, specifically to drive the Scanspeak. This would decouple the Scanspeaks from the Milq and would let midbass to run very free. I do not see any ready to go SS followers available for sale. I do not want to build it and I do not want to vandalize my SS amps to covert thermo followers. So, I end up with filtering out LF from midbass in order to help Milq a bit. The surprise I got that as I was changing   the filtering capacitor, moving the Vitavox ‘s high pass I got a very nice boost at the lower knee of my woofer tower. The amassing thins that this LF boos as I have now is +2.5dB at 20Hz compare to midbass is not connected or compare the Vitavox is not high passed! I have no idea why it does it and it can’t be explained by Milq loading more and yield more power as with no filtering cap in Vitavox the load should be even more. I asked Dima and he thinks that the coil and filter former some kind of response chain that acts like Zobel and rise impedance more than bypass and overcorrect the amp gain. Nevertheless, the extra LF boost at 20Hz is very welcoming thing and it look like the boost goes away at 30Hz. As I start listening it I will see how it sound but it is in sub 30Hz, so it might be work out very nicely. 
 
Now, is the elephant in the room: the midbass channels and what I did with it? I named it phase joker. To position it at time-aligned position was not possible as any of my experiment with crossovers did not allow me to have horrible room modes. I tried zillion positions in the room, doe one, two and three Vitavox cubes, with all possible polarity, all possible crossovers. Nothing worked and if I serve the dams of upper bass I always get fucked by lower bass. I want the slopes to be in phase and to be summing but I was not able to find this configuration. Then I decided to screw it and stop worry about timing and I flipped the midbass Vitavox at 90 degree.  I was able to find a good position, in fact near to time-alignment when I have summing boost on both LF and Upper bass with midbass filing the amplitude gap very nicely. 
 
I am setting today the second channel the same configuration and will do some listening. I am very pleased that I was able to find this setting but a few things need to be said. The idea of using my narrow bandwidth midbass as “distributed, strategically injected phase anomaly” might be considered as elegant in my situation, however from my perspective it is a huge white flag. What I did was polluting my listening space with phase junk and this is not something that I would advise as sane playback building techniques. The way how the problem with my room shall be dealt if I have time should be very different. I would need to come up with a topology of midbass that would be able to work along with the rest of my system with coherent phase and time-alignment. I presume that it will be a midbass horn where the location and size of the mouth will overcome the room mode but it will be a project for another day.
Romy The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
10-01-2017 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,570
Joined on 10-12-2006

Post #: 219
Post ID: 23427
Reply to: 23426
Sum and Difference
Romy, you said you tried 1, 2 and 3 mid-bass boxes, and you tried moving them around.  Using 1 box in its "best spot" as the basis, can you re-tell specifics with summing and cancellation when you add another box (or 2)?  What sort of large value caps are you using in the X/O?


Paul S
10-01-2017 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,049
Joined on 05-28-2004

Post #: 220
Post ID: 23428
Reply to: 23427
It is in the picture...
 Paul S wrote:
What sort of large value caps are you using in the X/O?
Electrolytics of course.


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
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