| Illusus |
Currently under development :smash:
Fe166esr on OB and JBL E140 in BR, XO is centered around 180Hz. Baltic Birch ply construction, double thickness baffle, well braced.
Crossover stil needs messing around with, first order on FE1666, second order on E140, it's at the most rudimentary stage right now, sitting on a board. It seems to sound better with the FE1666 running wide open than with the cap. I think the woofer may need a contour network. There are other options I'm considering too(see last paragraph).
I need to adjust the stuffing, I just covered the back, top and one side with acoustic wool insulation to start...sounds like I need to take some out. I used more complex bracing than I intended and lost some Vb, so I overstuffed to compensate, that 'wool' **** is extremely dense.
I'm working on a grill for the back of the OB, it's a cage made of mild steel rod that continues the BR box shape, filling in that giant notch. There will be a grill on the woofer as well.
Also, I'm still picking out a finish...Either a really crazy (wild burl, or lacewood or some other exotic) veneer or perhaps leather on the baffle. Whatever I end up doing it'll be high zoot ;)
Now for a slightly OT question. I am about to finish my Pass BLS(BOSOZ or whatever), I also have four channels of ZenV4. I want to either build a pair of Balanced ZenV4 monoblocks and stick with passive XO or go active and bi-amp. What, in your opinion, is the better way to go?
P.S. pardon my syntax, I'm kind of out of 'it'. I just got home from the hospital...I was there for a few days, I smashed up my mouth pretty bad (snowboarding F'up-darn rails!) so I'm pretty pilled up, hehe. |
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| Ropie |
I like the look of those a lot.
I bet they will sound as good as they look too! |
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| Illusus |
Thanks. They already sound better than anything I've had in my home. I got a little lucky with how well the drivers integrate right off the bat. Imaging is good, detail is fantastic, midrange is near bliss(the Fostex need to break in a bit, still sound 'chesty') and the bass is just right, I've had a chance to really open them up when my landlord went to bingo :D, you can really feel the kick drum punch you in the gut. There is less overhang than I've ever heard, low bass notes start and stop as they should. With all my previous speakers I had to listen hard to hear the drums in rock music, they'd always get lost behind a wall of guitar, now all instruments are clearly audible, I don't have to strain my mind to filter out all the instruments I'm not focusing on, I just pic the instrument and there it is...well, when I feel like listening that way.
I'm not going to fool with them for some time, I'm going to wait untill the Fostex drivers break in.
I'll take a couple of better pictures when my head clears. That pic doesn't do them justice. It's hard to get perspective accross with that pic, it's mostly built with compound mitre joints...I sure had fun building them.
Here's a ('nother bad) pic of the back |
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| Ropie |
Yes, the workmanship on those looks pretty tight.
Last week I made some similar looking things out of cardboard, just as a test run. The midrange driver in a small baffle on top of a bass 'box' of some description seems to be a good configuration. The sound from mine was very natural and smooth.
Will you 'release' the plans at all when they're done? |
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| Illusus |
| quote: | Originally posted by Ropie
Will you 'release' the plans at all when they're done? |
Probably just the basics, Vb, Fb, baffle size...etc. No cut list or anything. |
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| Josephjcole |
Illusus
I have to admit to a slight tinge of jealousy. They look very nice, and I'm sure they sound good as well. Quite impressive that you good a good crossover from the get go. On my fostex108, emminence delta 12lf combo I keep wavering back and forth on different crossover points. Sometimes to thin, sometime to much mid-bass.....
Joe |
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| Illusus |
Thanks ;).
Yeah, I got pretty lucky. I was hoping I wouldn't have to stray too much from my original cross point, I don't have many parts left to experiment with. I used excessive modelling to get it 'virtually' right. It's tough working on a budget, I have to get everything right the first time. It ends up costing more out of the gate but I don't have to keep throwing money into my projects in the long run...I wish I had back the money I've lost on mediocre projects I built because the good stuff seemed expensive. |
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| Josephjcole |
I can understand that, at 180Hz I wouldn't want to buy anymore crossover parts than I had to. What did you use to model the crossover? I've used box simulation programs, but never crossover modeling programs. Might do me some good. Educate myself a little.
By the way, I was quite suprised that you can get the Fe166esr down to 180Hz on an open baffle. Seems like it would be fairly low q, and unable to go very low on open baffle. Sounds like you got it though.
Joe |
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| Illusus |
It was mostly done with pencil, paper, and a big earaser. I used the CMP program that came with a book by Weems/Koonce (book is so so BTW, these guys seem to assume a lot) for graphic output. I kept on cross referencing all my calcs using V.Dickason's Loudspeaker Cookbook and various imfo found on the web...mostly here. I like to stay clear of all the online calculators, I usually just use them to check my work otherwise I wouldn't really learn anything. I still think it was mostly luck.
I still have to measure response but I know you're right, it doesn't quite reach 180Hz (calcs showed it to be -1db at 200Hz from there it dropped like a rock), but the filter was designed for a fairly flat summed response where the drivers overlap. If I had brought the crossover closer to the OB's cancellation F there would be a big bump because of the woofers greater efficiency(100db/W). I wanted to stay clear of an L pad on the woofer, I thought the resistors might get pretty hot.
Anybody have any thoughts on the balanced VS active question from the first post in this thread? |
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| Nelson Pass |
| quote: | Originally posted by Illusus
Currently under development :smash:
Now for a slightly OT question. I am about to finish my Pass BLS(BOSOZ or whatever), I also have four channels of ZenV4. I want to either build a pair of Balanced ZenV4 monoblocks and stick with passive XO or go active and bi-amp. What, in your opinion, is the better way to go? |
I would try both - it's a lot like building two completely different
speakers, but with less work. |
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| one1speed |
Illusus
Question for you. You say this is the best system you've had in your place so far. Can you tell me what you've had to compare to and what you like better about this system? I'm wondering if you've compared to a BLH or similar. Thanks!
Layne |
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| Illusus |
I was thinking the same mr.Pass, afterall, I can build the amps to run balanced mono and SE stereo. Thanks for your help.
My speakers of late were FE206E in BLH...I also had the same drivers in ML TL cabs. They were both good but the ML TLs sounded a little too much like medical equipment (sterile, cold). The horns sounded very real and live but the sound would often get conjested, I had a hard time hearing toms and kick drums during semi-busy rock music. Orhestral pieces were a wall of sound, all low tones were only peeking out from behind the midrange. I tried many corrective circuits on both types of cabs, some good some bad. Of course, YMMV. I had guest listners in house quite often, most preferred the BLH over-all, but most liked the low end from from the TLs.
Before the 206 projects I had a slew of two and three way speakers, both DIY and commercial. All were so so.
How do these compare? It's hard to describe, the sound is just so different. When a kick drum hits it feels like you're standing right next to one. Low bass is fantastic, tight and tuneful. The imaging is already better, but I need to attenuate the back wave a bit, it seems to be adding an excess of confusing ambience to the stage. There is also a new level of 'realness', openness maybe? in the whole packge, especially the midrange, it really sounds natural and delicate. Only problem so far is the tiny sweet spot, it's about the size of a small beach ball, I can definitely tell when I poke my head out of it.
I really like the FE1666 drivers, very detailed, natural sounding. I'm amzed everytime I listen and hear nuances I've never heard before, new layers of harmonics, tiny details...I can't wait till they break in, if they're anything like the 206 I'm expecting some relatively big changes. |
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| one1speed |
| Thanks much, that's what I was looking for. Best of luck with it!! |
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| 5th element |
Have you factored bafflestep into any of this?
I see you mention the woofers sensativity is 100dB but after the conversion into 4pi you are really looking at 94dB. You are already about 3dB down at 200hz anyway due to this, coming full circle at about 100hz. I have estimated that your baffle width is about 18". |
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| Illusus |
you were pretty close on your estimate...they average about 18" near the woofer.
I thought about it a little(baffle step), I thought that the drop from baffle step would help even out the efficiency mismatch, I was wrong, upon first impression I was stunned by the gobs of bass but that's only because of lack of reference, my last speakers were very thin by comparison. I'm far from done though.
Yesterday the efficiency mismatch became very apparent through listening to frequency sweeps. I hooked up my warble tone generator(only tone generator I have-too lazy to burn a disk) and went through the frequencies. when I got to 200HZ there was a jump in volume, at least three db, enough to be obvious anyway. They sounded pretty flat in volume from 32Hz to 160HZ, then the jump in volume and again very flat up to about 16kHz. Inaudible at 20kHz, and I know I can hear that high, when I was foolin' around with FT17H STs I was hearing 20k, it's an annoying test tone, my cat went really nuts at 22kHz and above, I thought I could hear 22k but wasn't sure, I was definitely aware of it though.
So...last night I rigged up a pair of L-pads I had kicking around and toyed with them untill everything sounded flat, much better over-all but the bass sounded a bit bloated...I knew I over stuffed so I removed over half of what I had in there, much better. I mocked up some panels made of thin, stiff fiberglass insulation behind the OBs(I loosely boxed them in, I tore half the thickness off paper backed insulation panels) to damp the rear wave, it was causing a slightly confused sound, the fiberglass cleared it up a lot with no immediately apparent drawbacks - the midrange still sounds effortless and detailed but no more of that overly rich ambience. Imaging improved.
Now I wonder if I should work on a BSC or pad the upper driver, I don't really want to keep the L-pads in there. I'm in no hurry though so lots of time to spend in theory before making the choice. |
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| 5th element |
Well the good news is the open baffle speaker does not suffer from bafflestep losses because the driver radiates in 4pi all the time. However after the width of the baffle you get a loss of 6dB per octave and then 18dB per oc after driver resonance (IIRC), 50hz in your case. Im sure you know all this.
The way I would approach this is to cross the openbaffle to the bass driver at about 100hz, but in this case that is not possible, I would also use active filters just because I have them available to me. Shaping the lowpass on the bass driver should be able to compensate for the rise in response without having to add lots of compensation in other areas.
Once the low pass has sorted out the bafflestep loss on the bass driver there will be about a 1dB mismatch between the two drivers. Dont worry about this, we all get a small amount of room gain even if the speakers are placed free of the walls.
Assuming the JBL is flat for atleast 2 octaves past xover frequency and that impedance is constant in the xover region a textbook LWR4th order at 180hz is not far at all from an acoustic slope of the same design.
If however you are using a 2nd order slope then a text book crossover is much further from the acoustic. Both can be manipulated to provide almost perfect roll off. |
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| Illusus |
| just to play around with BSC I'm going to put in a line level circuit to-morrow, the corner is at about 85Hz...I should have no problems finding the parts in my bin. |
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| planet10 |
| quote: | | Originally posted by Illusus or go active and bi-amp |
At that low of a frequency active sure makes a lot of sense... even if just PLLXO.
dave |
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| Illusus |
That's pretty much the conclusion I'm arriving at. I will still configure the amps for use as both SE and Balanced. I'll participate in the MOX group buy if it goes through, till then I'll go with PLLXO. Now, what to do with those giant parts I bought?
If I use the preamp (BOSOZ) in SE mode, I just groung the unused inputs, right?
BTW...does the MOX support BSC as is or will I have to use the proto section?
Dave - check your eMail. |
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| one1speed |
| if there's anything more going on with this. Real interested to see where you land with this one, as I still like this direction... |
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| Illusus |
| At the moment I'm stuck due to a funds shortage. I put my Dynaco PAS2 hot-rod pre for sale on ebay, when it sells I'll be able to finish all my projects(I hope). Right now I'm using the time to design the line level XOs and BSC...I'm making the BSC variable so I can adjust if I move to a different room. Also, I'm waiting on veneer, working on the cage and grill for the back of the OB, designing a chassis and layout for a BLS(BOSOZ) and some ZEN4s...tons of ****. Sorry for making you wait;) . I say go for it, the OB sounds damn good to me and is not that hard to try, all you need is to fill in the bottom end somehow. Anything specific you're curious about? |
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| one1speed |
Just wanted to see how the whole thing panned out. I think I may have to wait a little bit, as I need funds to get LF drivers. At this point, I'm leaning towards the Fostex FW305 12". I like the fact that it goes low and will still be quick, costs a little more than I had planned, but not as much as JBLs or something.
You seem quite happy, so I think I'm going to go for it. Sounds like you have a lot of irons in the fire. Good luck with the projects, keep us posted! |
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| Illusus |
| I got very lucky with those JBLs. I was pawn shop browsing and saw these two giant 'roadie' boxes I took the lids off and there they were, along with some vintage AlNiCo 2402 horn tweeters, I paid $140 canadian for the pair and sold the tweeters on ebay for over $400 US. I carried that smile for some time, it still pops up...like right now. |
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| one1speed |
| Now that's what we call a deal!! Well done! I've never found anything at pawn shops or second hand stores. Then again, I don't look around that much. A truly good score. |
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| planet10 |
| quote: | Originally posted by one1speed
I've never found anything at pawn shops or second hand stores. |
:^)
That is how i generate a major portion of my meager income -- it is amazing what is out there to be found.
dave |
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| Illusus |
| I'm now going to design the PLLXOs. Any tips? I've been toying with the formulii found on Dave's PLLXO page but it seems a touch vague to me, how will this affect Q? . Should I go for 2nd order on the LP and 1st on the HP or 2nd or 1st for both? I suppose I'm fishing for an opinion on what you'd do given my situation. I also suppose I'm being a bit vague myself...anything you guys need to know to be able to help me out a bit? |
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| Illusus |
| I just stumbled on the link to Art Ludwig's couple paragraphs on the subject, it clears up a couple things(surprised I didn't notice it earlier)...also I remember an article in an issue of AudioExpress about somebody making one for their subwoofer, I'll see if I can dig that up. |
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| Illusus |
A little update,
I designed and implemented a passive line level BSC (RC) with 6db compensation, I tried 3db but due to speaker placement it sounded thin . It worked well to smooth out the bass response, there are still some holes and peaks but that's due to my room, although it has near perfect dimensions it's nearly untreated (except for the furniture), we don't plan on staying here too long so I haven't bothered. The BSC ate up some gain, but it's ok for now.
I also changed the xo. It was parallel, first order on the Fostex, 2nd order on the woofer, now it's first order series, sounds better, much better....there seemed to be a slight dip in the midbass before, the baffle cancelation occured above the xo point, first order on the woofer added the needed lift there. By nature, there should be a bit of combing now, but it doesn't seem noticeable from my listening position, there's a spot, when I move my head down and forward a couple of feet, where it's very obvious. I still haven't tried PLLXO or active...I'm going full balanced with my system but I'll leave the option for active xo/biamping just so I won't be in the dark.
Also, because I had some spare HQ(hovland) caps from a previous project, I cascaded(four steps) the big cap....I was a little sceptical of this practice but the midrange became a little more real and the highs clearer and more extended. I don't notice any tonal 'steps' as the f goes higher.
That's it for now. I have to wait untill my pre and amp parts come in untill I can try anything new, I sold my pre to fund my projects and have resorted to using my TV's extra I/O as a pre....it's not so good sounding. |
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