OB Horn Basszilla

[Illusus]

That is a diffusor not absorber. Still should make a difference.
BTW, here's a little variation on a Shroeder diffusor I slapped together out of boredom. It was supposed to be 3'x2'...but, ironically, I got bored of building it, therefore I stopped at 1'x2'.

[batdorf9]

Originally posted by Illusus
That is a diffusor not absorber. Still should make a difference.

whatever you call it, it works well.

link to foam stuff

[Illusus]

I hope I didn't 'read' like an ***... so hard to convey tone through a keyboard.

Those types of foam panels usually are made of open cell foam giving some absorbive quality, but they are designed to diffuse first. you can make your own much more effective absorbers for a lot less $. plus they look nice. Lots of info on the web.

Like your speaker by the way, angled baffle is cool.

[batdorf9]

Originally posted by Illusus
I hope I didn't 'read' like an ***... so hard to convey tone through a keyboard.

Like your speaker by the way, angled baffle is cool.

No offense taken.

Baffle design was sorted out in Tolvan's Edge program. I futzed around with it trying to get the bumps out, and this was about as good as I could do. I was trying to get down to 200 Hz or so. XO is around 300 Hz with a dbx driverack. The baffle is seperate from the box for the woofer to keep the baffle from vibrating so much.

Here's a screen grab from Tolvan's program...


- Robert

[johnb]

Nice speakers Batdorf9 , how do they sound, can you compare them to anything else you built.

John

[batdorf9]

Originally posted by johnb
Nice speakers Batdorf9 , how do they sound, can you compare them to anything else you built.

John

Thanks John. I was completely clueless when I built most of my other speakers. (Now I'm just partially clueless). So these definitely sound better than anything else I've ever had, but that's not saying much.

Out of the box, I must admit, I thought the Fostex sounded really nasty and harsh. There's a chance they needed to be broken in a bit -- I'm not sure. The dbx driverack is a marvelous device because it has a few parametric filters and a 1/3 octave EQ. So you can get just about any speaker to have a reasonably flat response (this makes comparing various speakers even harder). I have the trueaudio 1/24th octave rta program for measurements. Once EQ'd a bit the midrange quite good in my opinion. I don't have a lot of useful listening references to compare them too. The last time I was in a hi-fi hi-$ audio salon was probably 10 years ago. So my speakers sound great to me (and all of my non-audio-geek buddies that have been over here), but I can't make any terribly useful comparisons to help much.

I've never been thrilled with the highs coming out of the Fostex though. I'm beginning to put together the impression that full range drivers have good midrange, but crummy low bass and crummy highs. But I suspect that keeping a crossover out of the 300 - 10000 Hz range is a worthwhile cause. I've considered adding a super tweeter. I'll probably give that a whirl at some point. The Fostex FT17H is looking like a likely candidate.

Up until recently I had been driving the Fostex with an Adcom 2535 amp. Everyone seems pretty excited about tubes combined with the Fostex. So I picked up a couple used ASL Wave 8's. I got levels matched and such, so I could easily switch back and forth for A/B listening. With the Sovtek tubes, I easily prefered the sound of the the Adcom. My girlfriend even agreed. Next I switched to some Tehlam tubes. Things were noticably better than the Sovtek. So I listened to those for a while, but they weren't thrilling. Eventually I did a bit more A/B back and forth with the Adcom, and found it to be better. So the Wave 8's are going.

There's a bit of a question when EQing and setting levels, do you measure the nearfield response, or the response at the listening position. I suspect a combination would be best. EQ'd flat for the response at the listening position results in a pretty harsh midrange. In the end I settled on getting the nearfield response flat from 300 Hz up, and then getting the listening position reponse flat from 300 Hz down. The low frequency stuff is affected by the room too much for the nearfield response to be useful.

After the Fostex, my system gets complicated enough, that describing it in the "full-range" section, could lead to protests from the purists.

I tried the kilomax 18's in an open baffle first (Qts=0.56 and 10mm Xmax). I had figured with my baffle shape they would get down to 65 Hz or so reasonably well. But they didn't. I had a huge bump at 200 Hz and was pretty much done around 100 Hz. I suspect they may have been too close to the back wall. ??? I tried some baffle mods, H-thing and side "wings". Things got a bit better but now enough. Additionally, the woofers shook the baffles (just 3/4" mdf) enough you could feel pretty strong vibration at the top of the baffles. So that led me to build the sealed boxes for the kilomax. I haven't completely given up on OB, but it's going to have to be in my next house, not this one. So for now the 18's sit in some 8+ ft^3 sealed boxes.

The thing that's not show in the pics is that I crossover to some subwoofers at 45 Hz or so. There's two Dayton Titanic 15's in 3 ft^3 sealed boxes right behind the listening position. I use the delay in the driverack to delay the sub output, so things are pretty much aligned with the fronts. By having the sub very close the listening position, I get a bit more direct sound and a bit less room sound (I'm guessing).

I'm about to switch to a Rane RPM 26Z digital crossover (replacing the driverack). The Rane has an AES/EBU digital input, gobs of parametric EQ filters, and unlike all the other digital crossovers, actually has a clever way to control volume after all the D/A outputs. Bascially take the functionality of a behringer dcx2496, deq2496, and some homebrewed 6-channel volume control and combine it into one box. And the Rane has arguably better sounding DSP guts, (see Superior Audio Requires Fixed-Point DSP) On top of that the Rane people are infinitely cooler than the Behringer scoundrels.

- Robert


Better picture of the front of the room (and my dog Turbo) is attached here.

[planet10]

Wave 8

Not really the best flag carrier for tube amps... they sound OK, but should be considered a pre-assembled kit with some reworking needed right off the bat -- but for $200 they are good value.

For midrange duty something like a Decware ZEN or Bottlehead paramour (or new SEX amp) are better representatives of the tube low-end (and they can be improved on with some tweaking)

dave

[batdorf9]

Originally posted by planet10

For midrange duty something like a Decware ZEN or Bottlehead paramour (or new SEX amp) are better representatives of the tube low-end (and they can be improved on with some tweaking)

dave

Thanks for the input Dave. I was starting to think about trying a gainclone. I may look into either of these though. Too bad there's no easy way to just try one out for a week before buying it.


- Robert

[planet10]

Originally posted by batdorf9
I was starting to think about trying a gainclone.

A well done gainclone is not all too bad... pretty good matter of fact, especially if you need the power to drive a "convential speaker". So far in the shootouts we have had between GC (Brian GT red board with all the good Rs, the pano caps, and a 300 VA 40-0-40 run at 20-0-20) and various evolutionary EL84 amps (that started out as a "close as we could get" to the Decware ZEN) the 2 W EL84 amp is a clear winner (this on speakers where 2 W is enuff). The GC has better bass and i wouldn't hesittate to use it on woofers (i have some Tamura OPTs with 600 ohm taps -- i was thinking that running the woofer amps off these would help maintain the same sonic signature for the bass amp)

I may look into either of these though. Too bad there's no easy way to just try one out for a week before buying it.

I believe Decware has a 30 day satisfaction on their pre-built amps. I'm lucky to have had these amps pass thru our local audio group so get to hear quite a variety. The local hifi dealer also has an "over the weekend" loaner policy which also helps.

dave