Well just because you use a transform doesn't mean to say you'll get some kind of silly low frequency response.
Moderation is the keyword here, a little low end EQ and I can get a frequency plot that is similar to the TL line without the hassle of a larger box with a long line and also avoid building a couple of prototypes to ensure correct labyrinth layout and stuffing densities.
I'm hoping to get a flat response down to about 30hz whilst maintaining high effeciency and avoiding large amplifiers. I suppose I could go down to 20hz flat if I wanted to but these are for music rather than HT. I can always augment the output with a large subwoofer for HT at a later stage for the floor shaking bass.
Of course not, I don't mind at all. People questioning my own decisions is a very good way to refine and review my choices and should there be obvious shortfalls then I can revise my plan. So its very much appreciated.
You wouldn't have any more info on the design your working on would you? Driver's, enclosures, loading, amp specs anything really. Sounds like we have many parallels is in our designs.
Thanks,
Ant
pinkmouse said:Well for me, the choice would be easy. The Volt B2500.1 is a natural match for the ATC.
I have some experience with Volt drivers and they are very much more at home in either vented or TL enclosures.
Sound quality is always high though and I've very little bad to say about them except they don't work as well in a sealed design and the driver baffle recess's annoy the hell out of me since I can just use the old circle jig.
Aurum Cantus G2/PR170M0/HM170Z0, xover is essentially 400/4000. 45L for the woofers, F3 47Hz. I posted earlier about it below...I've been working on the final enclosures and have yet to go back and tweak the XO more. I'll be using about 60W per driver, although this is complete overkill, even on the bass really. Just gainclones for now...I might get fancier later. I'm using a MOX setup to prototype.
http://www.diyaudio.com/forums/showthread.php?threadid=38794&highlight=
Essentially, your design appears to be the next step up from mine...more expensive drivers at each position, and about another octave of extension. If cost were no object, I would definitely audition the ATC mid...it appears to be an amazing driver.
As I said, I'm quite interested in your choice of XO. Do you think there is any mileage in me trying an all-pass to flip the phase of my drivers at XO, as opposed to inverting the mid? The idea of a truly (time and phase) aligned system is tempting...
I think I have almost convinced myself to try all this out on a DCX2496.
http://www.diyaudio.com/forums/showthread.php?threadid=38794&highlight=
Essentially, your design appears to be the next step up from mine...more expensive drivers at each position, and about another octave of extension. If cost were no object, I would definitely audition the ATC mid...it appears to be an amazing driver.
As I said, I'm quite interested in your choice of XO. Do you think there is any mileage in me trying an all-pass to flip the phase of my drivers at XO, as opposed to inverting the mid? The idea of a truly (time and phase) aligned system is tempting...
I think I have almost convinced myself to try all this out on a DCX2496.
ShinOBIWAN said:
Actually very low bass is neccesary to achieve the best audio. Extreme low freq.s effect freq. balance and also depth and soundstaging rather dramatically.
As to driver capable of doing what you requested this time.. that's a tough one.. I'd say look back at the offerings from Peerless (xxls) and Scan Speak. At one time P-Audio had a driver designed for this (TM-10).
Then there is the "King" of the group: the Aurasound NS10-794-4A (linear x-max is down right disturbing for a 10 inch driver). They are pricey and none to efficient, but if you are making a "no-holds-barred" system, what the hell.. You WILL need a powerfull amp though (in terms of current primarily.. see below) In case you are wondering if this is the "best" there is - the Co. referred to here in 6moons seems to think so (and they do seek out the "best" regardless of price, and are using what appears to be the 15 inch version in their "Ultimate" design):
http://www.6moons.com/audioreviews/magico/mini.html
Like I mentioned b4, most homes in the UK will have serious "bass lift" starting as high as the upper 30's because of masonry walls. If your "flat" has this - then eq. may be less than you might think (and as a result may enable your proposed design with far less watt's required).
tiroth said:
Looks like a great project you've got going on there. Perhaps I can pick your brains when I'm in the testing stages.
The ATC is undoubtable the best mid I've ever had the fortune to hear. Testing on an open baffle reveals it to be an extremely natural and detailed performer but it also does all this in an unforced fashion. The scan again mates with these qualities and initial test prove it to be a great match to the ATC, couldn't imagine better.
The only problem with all this is that it tends to spoil you, all the stuff you thought sounded great now sounds so so in a direct comparison. I have some Visaton MHT12 ribbons and TI100 mid/bass drivers in a passive 2 way and they sound dynamically retarted, meaning small & compressed in comparison. Yet without a side by side test they sound great
You could try an allpass network looking at your plots. Its certainly more preferable to try to work the problem that way than to just use a brute force narrow notch filter.
Its hard to say conclusively, you don't happen to have any phase plots do you?
I think I have almost convinced myself to try all this out on a DCX2496.
The Behringer is a great tool for prototyping, quick and easy to try out lots of different slopes, points, EQ etc. Its how I always start work and then move onto build the actual XO's once I've decided on something that I think is good. Cuts out hours of messing around swapping caps and resistors.
I wouldn't recommend keeping it in the loop as the permanant crossover since its not the most transparent device but as a tool its unrivaled at its price.
You may want to consider a TC Sounds TC2 or TC9 10" woofer. Those drivers have a great reputation for being very clean, accurate, low distortion woofers. They also have a high x-max and high power handling. The only potential drawback may be whether they have a clean response up to 500hz, and what kind of cone breakup there is. As long as the breakup can be managed and their bandwidth is suitable, I think they would be a great candidate for a LR transform.
Right update time.
After much time researching I've eventually settled on 6 x Sea's L22 RN4X/P. Not the most exotic choice considering the partnering drivers but after working through many variables including cost these are my final choices.
Three drivers per cabinet working in a sealed box of ~60ltr(after bracing and driver displacement. Front baffle will be 38mm thick.
I've taken up Scott on his advice and decided on some thing that will go low hence a Linkwitz transform for flat response to 20hz.
Have all the MDF so after I've run the drivers in and then tested them in SW, I'll tweak the box and LR circuit as nessecary.
So now all the major decision's have been made its just a case build, test and tweak.
Pictures will of the first stages of construction will be up very soon
Getting excited now!
After much time researching I've eventually settled on 6 x Sea's L22 RN4X/P. Not the most exotic choice considering the partnering drivers but after working through many variables including cost these are my final choices.
Three drivers per cabinet working in a sealed box of ~60ltr(after bracing and driver displacement. Front baffle will be 38mm thick.
I've taken up Scott on his advice and decided on some thing that will go low hence a Linkwitz transform for flat response to 20hz.
Have all the MDF so after I've run the drivers in and then tested them in SW, I'll tweak the box and LR circuit as nessecary.
So now all the major decision's have been made its just a case build, test and tweak.
Pictures will of the first stages of construction will be up very soon
Getting excited now!
Outline of the final enclosure design:
Total dimensions are(WxHxD): 30 x 110 x 51cm
An externally hosted image should be here but it was not working when we last tested it.
Total dimensions are(WxHxD): 30 x 110 x 51cm
tiroth said:At the risk of sounding like a third grader: no fair cheating.
You design good Tiroth
Seriously though I based my speakers on the Von Schweikert VR-4SR:
An externally hosted image should be here but it was not working when we last tested it.
I'm not keen on the veneer so I'll probably get the cabinets into a spray shop for a real nice gloss black finish
pinkmouse said:That's quite a steep slope on the mid-hi box. Have you checked the dispersion on the tweeter, ( I know the ATC will be fine
You might also have some crossover lobing issues if you are not careful...
Hi Pinkmouse,
The baffle angle from vertical is 16 degrees, so yes it is steep but that was the amount required to bring the drivers into time align.
Off-axis response on the Scan is average from my open baffle tests so far, though you wouldn't think it looking at the plots.
Hmm, what if I were to bring the top section of the sloping baffle back in to vertical just for the tweeter?
With RE to the bass alignment.
I have a HIGHLY absorbtive/diffusive, very large listening room, and about two months ago I finished a sealed box speaker with a Q of .7 and an F3 of about 51 Hz, I did this to properly match to my room. It indeed does match to my room and provides flat bass response well into the upper 20's. However, in a smaller, 'stiffer' room, this spekaer would probably be overpowering in the 50-100Hz range. I would be very careful about the speaker-room match, as proper leveling in this reigon can make or break a full-range speaker geared towards accurate response.
I would start by making a sealed box with a single L22 in it, and just measuring it nearfield and then placing it in several aproximate speaker locations for a reality check. Nearfield it should roll-off early and if your room is small and stiff, it will probably provide good flat bass down to the 30's or so would be my guess, but maybe with a broad-ish dip if it really starts to roll-off early nearfield.
-Paul
I have a HIGHLY absorbtive/diffusive, very large listening room, and about two months ago I finished a sealed box speaker with a Q of .7 and an F3 of about 51 Hz, I did this to properly match to my room. It indeed does match to my room and provides flat bass response well into the upper 20's. However, in a smaller, 'stiffer' room, this spekaer would probably be overpowering in the 50-100Hz range. I would be very careful about the speaker-room match, as proper leveling in this reigon can make or break a full-range speaker geared towards accurate response.
I would start by making a sealed box with a single L22 in it, and just measuring it nearfield and then placing it in several aproximate speaker locations for a reality check. Nearfield it should roll-off early and if your room is small and stiff, it will probably provide good flat bass down to the 30's or so would be my guess, but maybe with a broad-ish dip if it really starts to roll-off early nearfield.
-Paul
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