Page 5 of 7 FirstFirst ... 34567 LastLast
Results 61 to 75 of 97

Thread: Do you time align your drivers ?

  1. #61
    Senior Member 1audiohack's Avatar
    Join Date
    Jul 2007
    Location
    Las Vegas Nevada
    Posts
    2,701
    I don't know that's right. jblsound
    Your right! In my haste I didn't type half of it. Sorry.

    To continue turn around and listen to the back half of the room with your hands cupped behind your ears. Your room by the description of it is probably pretty quiet back there. My living room however is almost as bright off the back wall.

    No more half conscious posts from me 'till after Baja. Sorry again.

    Barry.

  2. #62
    JBL 4645
    Guest
    Quote Originally Posted by 1audiohack View Post
    Your right! In my haste I didn't type half of it. Sorry.

    To continue turn around and listen to the back half of the room with your hands cupped behind your ears. Your room by the description of it is probably pretty quiet back there. My living room however is almost as bright off the back wall.

    No more half conscious posts from me 'till after Baja. Sorry again.

    Barry.
    A tiny amount of high frequency absorbent placed around the back half sidewalls and along the back wall might reduce the brightness of shrilling highs.

    How does such a manufacture like JBL time align their LSR models which are active powered?

    Do they use narrow range pink noise or full spectrum pink noise or sine wave tone centred near the crossover points?

    Where is the microphone placed and are there any pictures as pictures says a lot more.

  3. #63
    Member
    Join Date
    Oct 2009
    Location
    Italy
    Posts
    42
    Quote Originally Posted by JBL 4645 View Post
    ... Its good sense to listen on headphones then go back to the loudspeakers and see what is missing in terms of sound imaging detail that makes up for the sound stage.
    Maybe with this type of recording
    http://en.wikipedia.org/wiki/Dummy_head_recording
    is it possible to get spatial information even with headphone
    I have not tried for myself yet, but I still think it could be interesting
    In general I like very much that the recording transducers (mics) have a very "similar" geometry with that of the reproducing ones (headphones).
    It makes me a lot of sense.
    Kind regards,
    gino

  4. #64
    Senior Member Ian Mackenzie's Avatar
    Join Date
    Apr 2003
    Location
    Australia
    Posts
    7,122
    I will post a pic of a time aligned system (diy) I am building next week.

    The problem is not that manufacturers don't want to time align.

    Its how!

    Often physical constraints make it practically impossible to time align unless done so digitally.

    This is often the case with horn/ woofer two way systems.

    In a practical example the first take in my diy project I used an Emilar sand cast EH500 horn with a Tad 4001 driver. The total depth to the VC is about 25 cm.

    The woofer depth to the VC 13.5 cm.

    The difference is obviously 11.5cm

    By measuring the path lengths at a fixed point in space of 2.5 metres on axis with the horn we must compensate for about 4 cm between the horn and the woofer.

    The difference therefore becomes 7.5 cm.

    I arranged this with the dressed baffle using layers of 2.5cm structural plywood above and below the woofer is built up by 5 cm. A 2.5 cm flange around the horn mouth makes up the final amount of alignment. On a baffle of 56 cm width and 120 cm height the profile is visually acceptable.

    This makes the front baffle 3 inches thick in some places.

    The Emilar EH 500 is an exponential horn so the overall depth is not that great.

    If it were a hyperbolic horn the depth would be over 40 cm for the same cut off making time alignment more difficult. Tad solved this challenge by using very steep 6th order crossover slopes on the woofer @650 hertz which by design have enough group delay at the crossover point to align the woofer with the horn.

    Is time alignment audible?

    I think it depends on the application.

  5. #65
    Senior Member
    Join Date
    Feb 2007
    Location
    Christchurch, NZ
    Posts
    1,469
    Quote Originally Posted by Ian Mackenzie View Post
    The difference is obviously 11.5cm
    Try to physicaly time align a 2366 and a 2404.....in a cabinet.

  6. #66
    JBL 4645
    Guest
    Quote Originally Posted by ginetto61 View Post
    Maybe with this type of recording
    http://en.wikipedia.org/wiki/Dummy_head_recording
    is it possible to get spatial information even with headphone
    I have not tried for myself yet, but I still think it could be interesting
    In general I like very much that the recording transducers (mics) have a very "similar" geometry with that of the reproducing ones (headphones).
    It makes me a lot of sense.
    Kind regards,
    gino
    Yes, yes the dummy head, of course. I read in an article that I found in building a Hi-Fi magazine which I still have, found it around 1989.

    Would one of those polystyrene heads work as dummy head the ones that they use for displaying wigs? Drill a few holes in the sides and tuck small microphone inside it.




    Edit:
    The prices here might make you faint!
    I mean look at the face looks more like an android than human face.
    http://www.dv247.com/microphones/neumann-ku-100-dummy-head-binaural-stereo-microphone--21004

    Build Your Own Binaural Dummy-Head!
    http://www.binaural.com/serendipity/...tructions.html
    http://digdagga.com/dummy/index.html

    There are several videos here on this link page for binaural dummy heads
    http://www.youtube.com/results?search_query=+binaural+dummy+head&search_t ype=&aq=f

    I liked this video for its ambient sound of the garden while it rains, sounds neat with the headphones on at soft level, so that you can hear yourself breathing, if you know what I mean because then it would seem even more real.

    Binaural Example (you must wear headphones)
    http://www.youtube.com/watch?v=9zQn-Ae9t1g

  7. #67
    Member
    Join Date
    Oct 2009
    Location
    Italy
    Posts
    42
    Good evening and thank you very much for the very interesting link
    looking at those price I am thinking to propose myself as a rentable dummy head
    My reasoning is maybe a nonsense but I wonder is there should be some similarities between the geometrical shape of the diaphragm of the microphone and that of the replaying speaker, of course with different dimension
    If for example the diaphragm of the microphone is cilindrical than also that of the replaying speaker must be cilindrical, and in this case an omnidirectional speaker should be the best way to reproduce the recorded sound.
    I could not find a detailed drawing of a microphone capsule
    A scaled-up microphone capsule could result in a very nice speaker
    I said .. this is more a nonsense than a reasoning
    But I believe is the reason why binaural recording sound so realistic and impressive when listening with an headphone
    Thanks again and kind regards,
    gino

  8. #68
    Senior Member lgvenable's Avatar
    Join Date
    Apr 2005
    Location
    Broken Arrow OK
    Posts
    558
    the sound engineer I'm working with has suggested time alignment as I move to a bi-amped or tri-amp system. His suggestion was to use a dBX driverack260 to time align any horns which might be slightly out of phase with the other speakers in a channel which is being bi or tri-amped.

    He sets up systems locally, then uses a computer and an RTA to determine the offset to digitally correct the time alignment. The dBX is Harmon product, and contains some JBL speaker parameters in its firmware, price each; from a shop I found on Amazon 550, otherwise 1000 each.
    Integra DHC80.1,3x 4636LF, 2360-2446J 2404H,12 x 8340 Surrounds, 2 x4645B, BGW 250D's,250E's,& 750B's 16 amps...7600 watts

  9. #69
    JBL 4645
    Guest
    Also I find the time-align with the sub bass extension for the LCR fronts a benefit when running a few frequency sweeps I can see a few gaps between one of each LCR and then run the same sweep over again only with the sub on and the LCR fronts muted on the DCX2496 I can see where the gaps are and when applying one of the LCR one at time with sub bass extension and few adjustments of the time-align it strengths up the gaps within the listening area.

    Ill run a few sweeps and show some examples, may take an hour or two.

  10. #70
    JBL 4645
    Guest
    Okay knocked a quick example of the difference when adding time delay on one the LCR fronts in this case I used the centre front with sub bass extension ON and OFF and one with time-delay ON and OFF.

    You can see the gaps in the frequency response due to the dreaded null room issue that is common in every room. a few peaks and dips. I prefer spectrumlab as it shows the issue quicker over REW and I can run the test repeatedly on (loop) while making some minor adjustments.

    The hot colours need to be softened a bit and I’m fresh out of EQ filters on the DCX2496 now.

    I used my SPL db metre connected up to the pc as the preamp for my ECM8000 has buggered up on me. Sigh at least I have back-up!

    Note the gab between 78Hz and the time delay seems to fix that tiny little gab.

    The gabs between 40Hz and 70Hz and about 80Hz to 105Hz is inexcusable and really needs to be sorted ether with a bit more power and trim the EQ down on the hot spots.

    I’ll try the SPL db placed near to the LF and HF and see if it will show up on spectrumlab. Only thing is setting the spectrumlab up for higher frequency response is bit of dogs dinner as I have to change the settings.
    Attached Images Attached Images  

  11. #71
    JBL 4645
    Guest
    As you can see the spectrumlab shows up the gap in the short frequency sweep that I used for 900Hz to 2KHz. I added some delay which seems to fix the slight gap. Im not going to muck around with the EQ settings as it took me hours to do a few weeks ago.

    I had to lower the level of the LF as the colour was too strong and the HF was somewhat less but I can hear the top range.

    Not the gaps between delay ON and OFF.

    The SPL db was placed vertical between the control 5 at few inches away.

    There is that other gap Im, not that blind yet! That can be fixed with a bit more tinkering around.
    Attached Images Attached Images  

  12. #72
    JBL 4645
    Guest
    That’s just as about far as I can push the spectrumlab I can’t seem to get it any higher than 5KHz. Apart from the short sine wave sweep busting my ears almost the response looks fairly even enough on the centre front.

    The noise yes that is noise being picked-up in the lower part of the graph as I live in crappy neighbourhood with loud noisy traffic! (Hey you noisy buggers out there keep it down I’m working in here)!

    The graph may look better for highs on REW as the resolution gets a bit messy on spectrumlab when running it at higher frequencies.

    SPL db was placed at the listening location on this frequency sweep run.
    Attached Images Attached Images  

  13. #73
    Senior Member
    Join Date
    Sep 2008
    Location
    Germany / Hamburg
    Posts
    588
    This topic is ancient but very interesting and still relevant!


    I do believe time alignment cannot be harmful, but it`s simply impractical and visionary to time align a big horn and a woofer in a box!
    I don`t like the looks of several drivers flying around the room just to be TA (time aligned). It is a pretty low WAF too, I guess...
    So if you`re instructed to mount all drivers in an usual enclosure, I simply don`t see a chance to TA ahorn/woofer such as a E-145 & 2395..
    A 6" thicker baffle at the horn`s location wouldn`t look any good...

    Im somehow stuck on my future enclosure design due to the issue of TA.
    On the one hand, it seems to make sense. On the other hand there a plenty of fantastic sounding speakers out there with very poor TA...
    So what`s the deal....!?

  14. #74
    Heather [Senorita member] hjames's Avatar
    Join Date
    Nov 2005
    Location
    NoVA - DC 'burbs
    Posts
    8,341
    I've had a number of pairs of time-aligned speakers. I owned a pair of Dahlquist DQ10s, nice, but a bit quirky. Replaced them with multiple models of the DCM Timeframe transmission line speakers (Tf400/TF500/TF600/TF700/TF1000). Set up a whole surround system with the larger ones and it was impressive - but sold them all off except the TF600s (they make crazy nice rear surrounds...) After them I bought a couple pairs of Vandersteen 2 series speakers (2CEs and 2CIs) and they are my current keepers down in the TV/multichannel room. None of those were particularly ugly or had a bad SAF ... as a matter of fact, the Vandersteens are actually pretty charming. I also have a pair of KEF 105.4s with time align mid/tweeter top cabinets that are steerable - they have a great sound as well. I've taken a real liking to these various speakers that have a near magical imaging capability.

    I also have a pair of customized L200 with 22345. Walnut Smith horn on top with a 2445J, and top mounted 2405 slot at the very top -
    I have not taken the time to align them for best effect, but they are a pretty exciting way to listen to my music ... very dynamic.

    I'd say if you have a good listening space, try some Time Aligned speakers and see how they work for you.


    Quote Originally Posted by Dr.db View Post
    This topic is ancient but very interesting and still relevant!

    I do believe time alignment cannot be harmful, but it`s simply impractical and visionary to time align a big horn and a woofer in a box!
    I don`t like the looks of several drivers flying around the room just to be TA (time aligned). It is a pretty low WAF too, I guess...
    So if you`re instructed to mount all drivers in an usual enclosure, I simply don`t see a chance to TA ahorn/woofer such as a E-145 & 2395..
    A 6" thicker baffle at the horn`s location wouldn`t look any good...

    Im somehow stuck on my future enclosure design due to the issue of TA.
    On the one hand, it seems to make sense. On the other hand there a plenty of fantastic sounding speakers out there with very poor TA...
    So what`s the deal....!?
    2ch: Oppo, JoLida 502CRC, JBL L212, 18ti,240ti; Heath AS101, Von Schweikert VR4
    7.1: Oppo BDP103D, B&K, UREI 809A, JBL B460

  15. #75
    Senior Member Ian Mackenzie's Avatar
    Join Date
    Apr 2003
    Location
    Australia
    Posts
    7,122
    Building on this disucssion I have sort details of my current tower floor stander (Legend Acoustic - Kantu 6, Roger Crawford - ex Linn designer).

    This designer not only time aligned drivers but made use of customised drivers that could be mounted much closer together than normal and then researched the best overall driver locations for polar response optimisation and matched the crossver Q to drivers selected for good transient performance.

    If you look at Zaph Audio site there are numerous tests on all kinds of drivers and he is not afraid to call out the good from the bad.

    I think transient performance is often interpreted subjectively as time alignment when poor transient performance is symptomatic of delays or laggs in the impulse response of the signal after ot enters the crossover network and passes though the driver output.

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Affordable Quality Compression Drivers?
    By Mr. Widget in forum Lansing Product DIY Forum
    Replies: 3
    Last Post: 01-13-2009, 09:49 AM
  2. Vintage Horn Drivers
    By Soundwave in forum General Audio Discussion
    Replies: 3
    Last Post: 09-17-2008, 02:43 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •