Thanks for the kind words Romy. I am enjoying taking my time with this project and getting things just right. It sure helps when there is little development involved, just duplication more or less. Development may come later as I impose my expectations upon the playback, but we will see.
| Romy the Cat wrote:|
A major revision of what you do will take place when you
connect you bass line-array and will RTA your room from listening position.
There is absolutely no way to predict how room will response under 150Hz to
your playback. With the configuration you have you will have a LOT of options
to deal with whatever response you will get. Do not commit the stupidity many
audio people do and do not correct sub 150Hz with acoustic
treatments. It never works properly and create more problems then
solutions. The key should be not to fight
your room but use your room, converting the room problems into room advantages.
The configuration you have is uniquely suited for it. If you hit problems with
your RTA interpretation and would be confuse what steps to take with your
playback to address it then contact me and I will pitch some directions.
I see room treatment as one of the first things to get in order, but I am not thinking so much from the perspective of amplitude correction, rather trying to get a more even room decay. At present in my room, the further I get below 100Hz the longer the sound takes to decay. I personally find it a bit disconcerting but perhaps a lot of people would not even notice it ( I seem to hear low frequencies better than some). So my first step will be to make some pressure traps to go behind the speakers and in the corners and try to get them to reduce the room ringing/decay in the 30Hz to 500Hz region. Now that the Bass Cannons are up, I can hook them up to my existing amplifier and make some measurements to try to figure out just what I want to achieve. Just having the Cannons in the room has changed the bass sound that I get from the little standmounts that I currently use.
| Romy the Cat wrote:|
There is a direction that you might consider, I am taking about lower bass channel. I know that you have your wet dream fantasy about large midbass horn but there is topological restriction for you: time alignment. I do not know how to address this problem. The itch for midbass channel is not juts chowing over the “never stop paranoia”. The type of the drivers you use at LF are very good in my view at bottom but above let say 60-70Hz your can do better. You bass drivers have unique non-inertia rubber suspension which doe not feel like rubber and sonically very far from typical rubber used but it still not as loos as vintage paper suspension or leather suspension. Playing some lower MF or midbass instruments, you might feel that the micro-tensions and transients in midbass will be slightly mad out with your bass drivers. Honestly, it will not be felt as “deficiency” as those ScanSpeaks are very nicely balanced. What I did at my time was experimenting with loading. For instance, if I drive your bass driver from 6C33C then the best sound at 40Hz I got when I was loading my amp with let say 400R. However, the best sound at 120Hz I was getting from the same drivers if I load the amps with 1200R. At 1200R ScanSpeaks “ring” like a good vintage driver, well sort of… The irony is that in your configuration it is even possible to do it driving different section of the drivers in array from different taps of your OPT or even from different channels or Milq. It because a bit complex and you need to deal with power matching and a few other factors. I do think that much easy way to introduce little ridicules dedicated midbass channel with nice “loose” vintage driver, similar to what I did in my current room. The “ridicules” part come from that fact that it is not proper speaker. Above 125-150Hz you will have your upper-bass horn take over and at sub 70Hz you have your line-array cover nicely. So, it needs to be a very small little direct radiator box with 100dB efficiency. All that you need this driver to do is juts to inject some textural ringing around 100Hz. The wonderful irony is that 70Hz-100Hz is the exact location where most likely your room modes will be showing. So, you can combine your “injected textural ringing” with amplitude correction – very slick and effective way to deal with problems.
Regarding frequency response, I do have that 6th channel in the DSET that could be dedicated to an additional bass channel and I do have a pair of Vitavox 15" woofers that I found for the purpose. All of those options you mentioned are still on the table.
The room has an axial mode at just below 30Hz which can be nulled with correct placement of the listening chair exactly midway between those walls. Above that are other modes that are not so easy to mitigate but they do tend to cluster from 60/70Hz upwards. I can build broadband room treatment that will effectively reduce ringing and control the decay of those frequencies, but I doubt that it will do too much for the frequency response which I am quite sure will have to be treated as you suggest.