'LGT' Construction Diary

[ScottG]

Originally posted by ShinOBIWAN


Incongruous!

Does this mean a ban on all smilies? Looking back over the last couple of pages I probably nearly broke something with that quota.

No.. No ban!

Frankly I have the same stupid smile on my face.. got one of these:

http://www.pcnation.com/web/details....06&item=3W110T

..and I'm using it right now (sitting about 5 feet away) with a Vista Ultimate based comp. I built. I still can't believe how incredible it is (..it also doubles as a tanning bed).

[badman]

I get those often.... I'm lucky enough to have 3, count 'em, 3 excellent systems. From the sexy bedroom rig to the moderate office rig to the elaborate heil+rethm actively biamped main rig....


This is all too fun

[ShinOBIWAN]

Originally posted by Bratislav


Ahhh, that's better.
If you prefer your sax long, sustained and full of ambience try Jan Garbarek. He'll pack more emotion in two notes than Kenny G recorded in lifetime.

Some good stuff and varied. The man certainly has gone through a number of styles:

http://www.mp3.com/jan-garbarek/arti...om_clk=arttabs

[ShinOBIWAN]

Originally posted by ScottG



No.. No ban!

Frankly I have the same stupid smile on my face.. got one of these:

http://www.pcnation.com/web/details....06&item=3W110T

..and I'm using it right now (sitting about 5 feet away) with a Vista Ultimate based comp. I built. I still can't believe how incredible it is (..it also doubles as a tanning bed).

Ah full HD.

How's Vista Ultimate? I've been scared off from upgrading after hearing about issues with gaming and more worrying is sound support with some of the PC XO and measurement apps not playing ball.

[ScottG]

Originally posted by ShinOBIWAN


Ah full HD.

How's Vista Ultimate? I've been scared off from upgrading after hearing about issues with gaming and more worrying is sound support with some of the PC XO and measurement apps not playing ball.

I had all kinds of problems. Litterally a week of putzing about trying to get it the way I wanted.. but to no avail.

In most cases Vista is not the trouble maker (at least the 32 bit version I'm using).. rather its the hardware drivers. I was trying to get a raid mirror array going with my nforce 4 motherboard - but they don't have any stable drivers for it. Likewise my sli 7600GS cards don't have an sli driver.. so I'm sli-less (for likely the next month or so). Both are the fault of nvidia, not microslop. My sound card (creative labs fatal1ty) came out with drivers before I completed the install - and despite their beta status seem to work perfectly.

Vista's UAC can be problematic with some games.. there are some work arounds (like there were for XP), or you can simply disable the thing. Frankly the new free winpatrol (and an incoming and outgoing firewall) acomplishes the same thing with less hassel.

Beyond that though.. Its incredibly stable, but its also a memory hog. (I have 2 gig main memory and a suitable 4 gig flash drive for readyboost - and have absolutely no prob.s). One of the things I absolutely love about Vista is related to the Ultimate version: full computer backup. Unlike Vista's UAC, integrating the backup software with the OS ensures reliability. It works EXACTLY as it should (and I can't say that for any other backup utility I've used). You can backup to secondary hard disk or even write to DVDs (..or both as I've done). This allows complete recovery (a dream come true IMO).

Then there is the Aero interface - its pretty, its functional, not much else to say.

It is NOT an OS I'd simply "upgrade" to - to many horror stories there.. consider it a "fresh" build only.

Heck.. I even like the free Virtual PC 2007 (down loadable). I have a Win2000 build on it just for my internet browsing - completely "sand box" contained. So no risk of harming my Vista. In fact thats what I'm on right now.

[ShinOBIWAN]

Finally ordered the 8" drivers from AT.

We've taken the Flexunit 8 I 52 20 06 SD and changed the suspension compliance to suit sealed and give a target Q of 0.6 in a 35ltr enclosure. Per is also using the 8" C-Quenze cone as it offers more linear FR and finally we're using the Kapton former for best possible decay times and upper bass qualities.

Efficiency will be ~90dB above 130hz and then gradually falling off to ~80dB at 30hz.

All the usual stuff such as the symmetric drive and copper sleeve are left in place.

Still really enjoying the RAAL and AT cobble up. Been tweaking more and I have to say that moving the crossover point up has been rewarding, after experimenting the RAAL is perhaps too clean in the upper mids and you loose some of that tonal colour and feeling. At the moment I have it at 2.5Khz and think this sounds even better than 1.5Khz.

I also measured them and found that phase tracking is a bit of mess but after notching out and flattened the rising response of the AT 5" its given some very nice 2nd order acoustic slopes that show much more close to ideal. Its nice being able to use wideband drivers this time because getting target transfer functions is a doddle so to speak and these drivers have smooth impedance curves that just sit very well with each other - don't have any serious movement on the impedance from 20Khz all the way down to the AT's resonance. Really does sound cohesive and at peace with a feeling that nothing is emphasized over anything else. The soundstage is massive, I've never heard anything this large before except perhaps the MBL omni's but I think I've got a good bit over those because things are well placed and tightly defined within that stage.

I've only been tweaking and listening for a couple of days and already I have a sound that is most appealing. I'm considering changing this to an open baffle setup by reusing the baffles I've already build but building just sealed enclosures for the 8" bass drivers and leaving the mids OB. I'll hold off on that until I've tried these in the cabinets I planned to use from the start but its showing such huge promise that I'd be daft not to consider it.

If it does turn out into an OB then I think come the DIY meet later this year it will be very interesting for me to compare these directly with the Orions.

One thing that does intrigue me is that I'm using a couple of different things here to what I'd normally do - a ribbon, open baffle mids and very wide baffles (80cm). It could be that I'm hearing a distinctly different(and better) sound because of these factors and I maybe need to isolate and explore which of these is creating the appeal.

[LaMa]

Originally posted by ShinOBIWAN
Finally ordered the 8" drivers from AT.

We've taken the Flexunit 8 I 52 20 06 SD and changed the suspension compliance to suit sealed and give a target Q of 0.6 in a 35ltr enclosure. Per is also using the 8" C-Quenze cone as it offers more linear FR and finally we're using the Kapton former for best possible decay times and upper bass qualities.

Efficiency will be ~90dB above 130hz and then gradually falling off to ~80dB at 30hz.

All the usual stuff such as the symmetric drive and copper sleeve are left in place.

Still really enjoying the RAAL and AT cobble up. Been tweaking more and I have to say that moving the crossover point up has been rewarding, after experimenting the RAAL is perhaps too clean in the upper mids and you loose some of that tonal colour and feeling. At the moment I have it at 2.5Khz and think this sounds even better than 1.5Khz.

I also measured them and found that phase tracking is a bit of mess but after notching out and flattened the rising response of the AT 5" its given some very nice 2nd order acoustic slopes that show much more close to ideal. Its nice being able to use wideband drivers this time because getting target transfer functions is a doddle so to speak and these drivers have smooth impedance curves that just sit very well with each other - don't have any serious movement on the impedance from 20Khz all the way down to the AT's resonance. Really does sound cohesive and at peace with a feeling that nothing is emphasized over anything else. The soundstage is massive, I've never heard anything this large before except perhaps the MBL omni's but I think I've got a good bit over those because things are well placed and tightly defined within that stage.

I've only been tweaking and listening for a couple of days and already I have a sound that is most appealing. I'm considering changing this to an open baffle setup by reusing the baffles I've already build but building just sealed enclosures for the 8" bass drivers and leaving the mids OB. I'll hold off on that until I've tried these in the cabinets I planned to use from the start but its showing such huge promise that I'd be daft not to consider it.

If it does turn out into an OB then I think come the DIY meet later this year it will be very interesting for me to compare these directly with the Orions.

One thing that does intrigue me is that I'm using a couple of different things here to what I'd normally do - a ribbon, open baffle mids and very wide baffles (80cm). It could be that I'm hearing a distinctly different(and better) sound because of these factors and I maybe need to isolate and explore which of these is creating the appeal.

Great to hear that you also like the Raal-Audiotechnology combination. Like I said before the Raal is one of the best sounding tweeters I've tried. And the combination with AT is very coherent. Also as mentioned by Linesource, stick to low XO points for your MTM configuration. In my own 3rd system (MTM with AT 15H and scan 6600) I tried several XO configurations and XO <2 kHz were preferable.

On another note, just because the AT and Raal are flat doesn't mean the xo work is more simple. Yes you can arrive at a very good sounding speaker in a few iterations, however, with these kind of drivers you want to arrive at really great sounding speakers ...

[tinitus]

Ok, Shin I misunderstood when first you wrote about Q=0.6

If its system Q=0.6, then it means that driver will have about 0.35 and seems like a good choise

[ScottG]

Originally posted by ShinOBIWAN


..I have to say that moving the crossover point up has been rewarding, after experimenting the RAAL is perhaps too clean in the upper mids and you loose some of that tonal colour and feeling. At the moment I have it at 2.5Khz and think this sounds even better than 1.5Khz.

If it does turn out into an OB then I think come the DIY meet later this year it will be very interesting for me to compare these directly with the Orions.

One thing that does intrigue me is that I'm using a couple of different things here to what I'd normally do - a ribbon, open baffle mids and very wide baffles (80cm). It could be that I'm hearing a distinctly different(and better) sound because of these factors and I maybe need to isolate and explore which of these is creating the appeal.

This is a matter of mass and acoustic center radiation I've mentioned before.. As freq.s decrease we tend to want more mass and a larger acoustic center (depending on listening distance). However this also depends on damping factor. With a very low/lossy damping factor due to a high output impeadance from a pairing amplifier - imaging and tonality seem to improve. So in this instance with your low output impeadance amplification you "need" the higher mass at a higher freq.. IF you go to a high output impeadance amp, then you will likely prefer a slightly lower highpass for the ribbon. In truth - even with a high output impeadance amp.. I found that people generally prefer a more "shallow" crossover point for at least an octave and a half above and below that point. It tends to blend the character of each driver better (but at the expense of increased distortion and spl-limiting).

As to the dipole/open baffle for the mids..

both a good idea and a bad idea.. When considering radiation character - BAD idea. (..it can be good though if your speakers are particularly close to your side walls and WELL away from your front wall.) When considering removal of the internal box limiting character - GOOD idea. Where a dipole really comes into its "own" is between about 300 Hz and 70-80 Hz. Beyond the removal of box induced character (in an open baffle format), I think its particular reason for sounding notably better is due to the side nulls, which seem to impart better subjective separation (..concerning the space between the speakers), and also do not couple to side walls to the same extent (..when concerning the first arrival reflection from a side wall). Notice NONE of this is specifically related to room modes (which are in fact every bit as effected by dipoles in this passband - though in a slightly different manner).

With that in mind - IF your cabinets are REALLY good for your mids (i.e. have little acoustic resistance, have moderately low pressure build-up, and "sink" most reflections), and IF you don't place them to close to the side walls of your listening room* - then you should not go dipole. If you do it will generate a "sameness of sound" with all recordings depending on the reflections the rear phase signal generates with the room. (..not dissimilar to having an expander processor that generates a bigger soundstage *all* the time.)

*for the distance look to the wavelength of your mids via a calculator like this one:

http://www.mcsquared.com/wavelength.htm

All that said - with a good amp I'd expect your creation will trounce the Orion's in all areas except perhaps midbass clarity. There you should hear a less forward character to image placement - especially when concerning instruments like bass guitars, drums, and pianos. Just a guess though.

[holdent]

Getting past the "are ribbons the best" argument (a big step for me!), I'd like to add a caution to the mixed box/OB suggestions. I've never built one due to the difficulties optimizing them reported by others such as Tony Gee and his Modulus (ribbon & OB mid & sealed woofer - see http://www.humblehomemadehifi.com/Modulus.html). In the 6Moons review of the Bastanis Prometheus Mk II they also note set-up problems (http://www.6moons.com/audioreviews/b...rometheus.html).

I've built a number of fullrange, TQWT boxes, several BR and sealed designs, and most recently, two OBs. I think the sound from the OBs are the best I've heard (and, of course, they are remarkably easy to build!). But OBs, as ScottG points out, need to be pulled out from the wall. In my living room they really need to be at least 1.0 m out. I would also agree with what I think ScottG is suggesting -- OBs function best if the bass is OB and the midrange+tweeter aren't.