Any information how the above woofers would perform in an open baffle (appr. 0,6x0,7m) equalized and active crossover at 5oohz to an Altec 511B horn.
Is the above a good idea ?
Printable View
Any information how the above woofers would perform in an open baffle (appr. 0,6x0,7m) equalized and active crossover at 5oohz to an Altec 511B horn.
Is the above a good idea ?
I'll take a shot--
Both of these woofers are low Qt, which means that they will begin their lf roll off at a relatively high frequency -- so if you want to eq them flat into the lower bass range, because of dipole cancellation they will need considerable power and will likely run out of excursion and/or hit their vc power limitations at a relatively low spl. Of the two, the 3154 has a lower fs and higher excursion limits so between them, this would be my pick for OB -- but it would not be ideal.
OTOH, look at the Carver Amazing speakers. They used very high Qt woofers which had huge excursion and were ganged 3 or 4 a side for bass output down to the 20s without eq. Ingenious.
If you want to do Altec open baffle best shot is likely 420A
Altec Thiele-Small Parameters
Higher Qts is better for OB
From much earlier today: RE: Altec 15 inch 3154, or 416 in open baffle - GM - High Efficiency Speaker Asylum
GM
GM - you're a damn guru. I swear I need to ready like 10 reference docs to interpret your posts. <respect>
Only 10?! I'm slipping in my dotage. :( I know how you feel though, Some years ago I decided to learn as much about antenna design as I knew about acoustical stuff, so already knowing the TL, horn analogies between the two, I went straight to the advanced designer's forum and most of it might as well have been posted in Sanskrit and Greek since it was loaded with their own specialized lingo and higher math intensive; plus it was obvious that they didn't suffer fools graciously and the mods would ban anyone that was there to get free design theory info that could be found searching the beginner, etc. forums. A really tough crowd compared to the audio/HT forums.
Consequently, I didn't learn much, but ultimately the 'crew' did what I wanted to do, which was design an OTA digital TV antenna for 'problem' areas like mine, though I have no clue how it was done since they declined to publish its design details.
GM
He's a smart cookie alright.Quote:
Originally Posted by Alien_Shore
I wish! If I was, I'd of been able to do more than just lurk for ~ a year on that forum before giving up.
GM
I just call him "The Man" :Big smile: And a damn generous one at that too !Quote:
Originally Posted by Alien_Shore
I agree that the X-max of the 416 could be a problem. You don't get much bass efficiency out of an OB (that's why they put woofers in boxes) so you have to push the cone farther. That said, I've run across a number of 416s that had a Qts of 0.4 to 0.6 and that means more of a bass bump than factory specs would indicate. But less efficient, so it's a trade off.
Another thing hard to get right is the crossover. Mating an open baffle woofer and a horn is no easy task - I speak from experience! It can be done, but won't look anything like a textbook crossover.
See attached my Selenium 15" + Altec 811 Obee. It later had wings to help the bass.
I can't understand why anyone would want to go the OB route with all its limitaions. We are trying to reach down to 20Hz, after all aren't we?
OG: sometimes I ask questions I guess I shouldn't ask and this may be one more time. Let me lead up to it this way. I've had HD TV over the air, OTA, for I'd say ane easy 8 years already, pretty much when they started broadcasting it, and I've always used a "normal" TV antenna with an amplifier. The only problems I've had is when weather, aka heavy overcast & rain causes the signal to drop out on only some channels sometimes because its all on the UHF band now. I'm in the shadow of a large hill but not the lowest spot in the valley, so I get a pretty fair signal considering my limitations from all the greater Boston area.
Is there really something special in having a "digital" antenna?
IMHO no. Digital rated is a sales gimmick, I don't think any kind of standard. OTOH there are better antennas that have more range. Amazon is a good place to do homework and check reviews. Check the negs though, they might be about the seller. Amazon lumps all reviews together, and users are too dumb to leave feedback.
(tongue in cheek) At least with DSP in audio, the speakers are still analogue and the Atlecs have great dynaimic range and surely are "digital ready" (already a tired phrase.)
LOL! 'digital' WRT antennas just means it can be much smaller than an old 'analog' one. I built a little coat hanger design shown on a youtube video and got a better picture on some channels than the guy next door with his $100/mo. Comcast cable system. I had to make another one to create an array though to get the rest due to the close proximity of an airport, microwave towers and large trees shadowing my house, plus for the local PBS channels I had to parallel an old DIY FM dipole to pick up their lower frequencies.
Of course what I really need is my big old tech, rotating roof antenna that lightning cooked some years ago.
GM
Cable tv is useful when there is no alternative. It does not mean its better than sliced bread. Most homes around me have cable for "convenience" I guess, not to mention the sometimes mind numbing content. But they charge extra for HD.
There are still antennas fo which you speak available as you know, but rotators like the AR-22 are hard to find and expensive.
I'm not. While it "may" be nice to have flat response down to 20Hz, it isn't very practical at home. Unless you listen to a lot of pipe organ music, dubstep or action movies there isn't much content down there. In fact, in many recordings there is just noise they forgot to take out in the mastering suite. You can get down into the 30s with OB, tho it's not easy. What you gain thru the rest of the spectrum by losing the bottom octave is often well worth the trade. IMO, of course.Quote:
Originally Posted by gvasale
Quote:
Originally Posted by GM
fellow responsible for the math behind small antennas....Benoit Mandelbrot. Pretty amazing stuff.
Benoit Mandelbrot - Wikipedia, the free encyclopedia
The Mandelbrot Set - "Thumbprint of God"
Fractal Geometry
http://www.bugman123.com/Fractals/index.html
GM: I have seen the PBS program about fractals. Interesting antennas and they're in virtually all cell phones.
Panomaniac: apologies, but I haven't experienced the gain you're describing. Seems like all my life I've wanted to get as much bass extension as possible, that is normal, not all beefed up with EQ, but I don't mind the speaker in the corner routine at all ( and I don't use subs for the stereo.) My old Zenith stand up radio, am & shortwave only ooperates in this manner, but I don't often prefer listening to it.
Maybe someday I'll run across someone who prefers OBs and I'll then get an idea.
Yeah, different goals. While I appreciate the lowest octave if I can have it, the range of ~60-300Hz is much more important to me. And so hard to get right.
FWIW, as much as I like open baffles, I run an Altec A5 system because I like the efficiency it gives me. Major work to get as clean bass as OB, tho.
Some fine sounding systems have limited bandwidth. Better to do a given range well than a wide range badly.
balanced.. same on both ends. not many folks can hear much of the top octive, and the lower octive is sooo hard to getQuote:
Originally Posted by Old Guy
I've heard the limited bandwith arguments before, and there may be some merit to it, but since I don't claim to be able to hear much higher than 10KHz today I really don't worry about it. At the other end of the spectrum I still prefer to get well below 50Hz if possible. Not because there's always some program material there, but when it is there the results are extremely rewarding.
They are, and can be unexpected. Like room tone and even a sense of the HVAC in the venue. Gives a great sense of being there. But hey, you gotta pick your battles. Mine are higher up. :D
I bought the Acoustic Elelgance 15 inch Dipole 15. Now I have to figure out how to crossover between the units (altec 511B horn) ?Quote:
Originally Posted by Panomaniac
Any information how to arrange the crossover settings ? Using an active Behringer DCX 2496 crossover.
Any information appreciated.
It's probably the best reason I enjoy Altec so much.What they do in their bandwidth they do very well.I too am partial to the low end of the bandwidth.I agree with Pano though, there is not much to hear down near 20 Hz. Mostly rumble that you can feel, but can't necessarily hear to well.But I also enjoy the high end too.Example, cymbals that hang in the air so to speak, with great clarity is what I look for in my speakers.With open baffles as Pano noted they can be very hard to get right and is probably why so many folks steer away from them. YMMV !
The only rumble I hear is the walls, windows, and cupboards rattling. Don't really care for it. No known instrument gets that close except for a church organ, and being a disbeliever, don't listen to too much of that. :)Quote:
Originally Posted by Altec Best
Sure: pipe organs, large bass drums, hall characteristics when previously mention instruments are active... It really all depends on what instrumentation was written into the music, and how up to date the recording is. Admittedly if I haven't said it before, you never know. But when it comes, it can be spectacular. Fortunately, I don't really have noise problems where I live, at least none that are extremely obnoxious for too long...unless I'm making them...I remember many years ago, I did a live recording at the factory so I could write something about it for the company quarterly. This was a sheet metal factory, made their own product. Big punch presses and things. When I reviewed the tape, I heard the low thud of one of the punch presses on the tape. Most of the HF energy of the machine had dissapated through the walls, corridors etc. leading to the conference room. But the pounding low frequency came through and actually recorded pretty well. I almost said WTF when I listened.
Start with an 800Hz, 2nd order hi-pass on the 511B. Use a 150Hz, 1st order low-pass on the 15" (yes, you read that right). That's your starting point. You'll want to add a HP shelf to the horn, maybe above 7K, I can't remember.Quote:
Originally Posted by MerlinVSM
If you don't have a lot of experience tuning crossovers by ear, this can be very frustrating. Some measurement equipment will greatly speed the project and lessen the frustration.
I was once at my daughter's junior high orchestra concert which had 5 slightly out of tune bass fiddles. Every now and then they would all be in tune and would shake the gymnasium like you wouldn't believe. :)Quote:
Originally Posted by gvasale