'Perceive' Contruction Diary

[pinkmouse]

Well for me, the choice would be easy. The Volt B2500.1 is a natural match for the ATC.

[ShinOBIWAN]

Originally posted by tiroth I'm curious about how the plan to use LT interacts with the statement that "floor pounding bass" isn't needed. How low do you want? In my experience, F3 around 50 can be quite authoritative in a sealed alignment. The advantage being, there are a lot more drivers to choose from in the Fs ~40 range that will deliver this performance at high efficiency. Also, I think it limits excursion and thus distortion.

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.

I hope you don't object to me picking your brain as you work through this process; it's of particular interest to me as I am also working on a TMWW design that seems to stem from similar design principles: high efficiency, a wideband true mid, coherent woofers, all active. I've already got the basic design done but I am still playing with the XO...I'm interested in 4th order because of the phase alignment benefits, but since I have a good-sounding 2nd-order XO, I'm afraid of the supposed sonic penalties of higher-order designs.

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

[ShinOBIWAN]

Originally posted by pinkmouse
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.

[tiroth]

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.

3-way Aurum Cantus, PR170M0 w/measurements

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.

[Variac]

Does the tweeter have the efficiency to keep up with the ATC Mid?

[ScottG]

Originally posted by ShinOBIWAN

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.

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).

[ShinOBIWAN]

Originally posted by tiroth
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.

3-way Aurum Cantus, PR170M0 w/measurements

Looks like a great project you've got going on there. Perhaps I can pick your brains when I'm in the testing stages.

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.

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

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...

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.

[ShinOBIWAN]

Originally posted by Variac
Does the tweeter have the efficiency to keep up with the ATC Mid?

The ATC is 94dB and the Scan is 94.5dB at 1w/1m, these are the MFR's quoted specs.

So are a good match and level matching should be close without too much use of the trimmers.

[ScottG]

Originally posted by ShinOBIWAN


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.

Thats good to hear. I was thinking that because the diaphram materials were similar that they would be "tonally matched", but you never know.. (and that kinda of expenditure is scarry on an unknown).

[ShinOBIWAN]

Originally posted by ScottG


Thats good to hear. I was thinking that because the diaphram materials were similar that they would be "tonally matched", but you never know.. (and that kinda of expenditure is scarry on an unknown).

Hence my concerns for the bass, there's a lot of information in 20-400hz that it will cover. It would be shame not to mention a waste of money should the early priliminary match between the ATC's and the Scan's be spoiled by an underachieving bass.