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In Praise of Aethers, Baffle Studies and LEDE

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  • DaveFred
    replied
    Originally posted by brianpowers27 View Post
    Re: In Praise of Aethers, Baffle Studies and LEDE



    Rudolf on Audiocircle helped me to understand the priciple behind using a narrowing baffle to displace the dipole rolloff to a better frequency. Here is picture of my 3 way with dipole woof, mid, tweet(2 tweeters per side). The xo points are around 250hz and 3000hz.

    The system is completely passive. The imaging is very precise.

    Do you have any more info on this build?

    A thread somewhere perhaps?

    Leave a comment:


  • dbe
    replied
    Re: Crossover Update

    Originally posted by dickwest View Post
    It seems the out of band breakup for the mid is not as severe as thought.

    In my 16 ohm MTM version I have settled on a .70 uF coil and 10 ohm/5 uF zobel to tame its top end and I note (by ear) no break up problems.

    It should be noted I did try several combos of coils and values and topologies (see xover previously posted). But, when the sound seemed to "gel" I quit. Not scientific, but pragmatic -- and it works for me .
    Man, you are on thin ice here with that subjective pragmatism The thing I like about voicing speakers is the latitude that we can take in the knee of the slopes to affect the audible result desired. By juggling high pass and low pass knees from one driver to another the same target response can be achieved but with different timbral characteristics due to the differing content contributions from the respective drivers. That is the part that I love - those little differences that give a speaker character.

    I've alway liked Audax mids especially the high sensitivity ones. They sound very immediate, if you know what I mean.

    Dave

    Leave a comment:


  • Paul Carmody
    replied
    Re: Crossover Update

    Originally posted by dickwest View Post
    It seems the out of band breakup for the mid is not as severe as thought. I don't have measurements so my comments are always suspect at this measurements oriented web site. The data published many years ago by Audax shows only a 3 db peak at the top end, not a "significant" break up. Attached is a fuzzy picture of the original Audax data for this driver.
    Yeah, overall I'd call that a pretty flat Frequency Response. Definitely a 1st order candidate ;)

    By the way, I'm really impressed, Dick. I still haven't gotten around to a full-on 1st order 3-way... and it's not for lack of Andy bugging me about it. :D

    Leave a comment:


  • dickwest
    replied
    Re: Crossover Update

    Originally posted by dbe View Post
    Dick,

    How did you deal with the out of band breakup that you noted in the mid?

    Dave

    The HM130ZO has some significant cone break up so 1st order filters are not really prudent to try for this driver.
    It seems the out of band breakup for the mid is not as severe as thought. I don't have measurements so my comments are always suspect at this measurements oriented web site. The data published many years ago by Audax shows only a 3 db peak at the top end, not a "significant" break up. Attached is a fuzzy picture of the original Audax data for this driver.

    I am familiar with the HM130ZO sound, having used it as a mid since 1996 (see my Avatar) in the Olsher designed PolyNatalia. Olsher's original xover only used a .47 mH coil on top plus a 10 ohm/2.2 uF zobel to tame its top end. Olsher also commented that the sound of this driver is so good that it can be run almost full out (full top range) and I tend to concur.

    In my 16 ohm MTM version I have settled on a .70 uF coil and 10 ohm/5 uF zobel to tame its top end and I note (by ear) no break up problems.

    It should be noted I did try several combos of coils and values and topologies (see xover previously posted). But, when the sound seemed to "gel" I quit. Not scientific, but pragmatic -- and it works for me .
    Attached Files

    Leave a comment:


  • dbe
    replied
    Re: Crossover Update

    Originally posted by dickwest View Post
    I did an update to this description of the xover:



    The entire xover is now 1st order both high and low pass for all drivers, and all drivers are connected in the same phase.
    Dick,

    How did you deal with the out of band breakup that you noted in the mid?

    Dave

    Leave a comment:


  • dickwest
    replied
    Crossover Update

    I did an update to this description of the xover:

    The low pass for the bass is the same as original -- 2nd order electrical.
    The high pass for the mid bandpass filter is 1st order which, when combined with baffle roll off beginning around 400 hz, should combine to make an acoustic 2nd order slope to match that of the bass high pass 2nd order filter.

    The low pass for the mid is about the same as shown in the schematic -- somewhat of a 2nd order. I fudged on the values of its inductors and used those on hand, but after trying various combos of those I have I settled for .70 and .25 mH which are a little different from what scaled or doubled values would dictate.

    The high pass for the tweeter is 2nd order electrical.

    The HM130ZO has some significant cone break up so 1st order filters are not really prudent to try for this driver.

    The mid and tweeter are connected out of phase with the woofer.
    The entire xover is now 1st order both high and low pass for all drivers, and all drivers are connected in the same phase.

    Leave a comment:


  • dbe
    replied
    Re: In Praise of Aethers, Baffle Studies and LEDE

    Originally posted by brianp View Post
    I suspect that trying to get an all-dipole system to behave with passive filters is beyond tricky and well-nigh onto futile. The John K and SL systems beat the problems into submission with multi-amplification, active crossovers and generous EQ. As frequency drops, this becomes more and more necessary.

    If you did want to fool with dipole woofers (H-frame, U-frame, W-frame or whatever), Danny Richie's new servo subs might fit the bill. I know he's developing something along those lines. Also, take a look at the ACI woofers that Mad just put on special. These things look like monsters, with high power handling and long linear excursion. They could be suitable, AND they're reasonably priced.
    Danny and I are working on a few things. I'll have to talk to him about the bass modules. My company will be sharing a suite with GR Research and Dodd Audio at RMAF this year. Hope you can come to Denver in Oct.

    Dave

    Leave a comment:


  • dbe
    replied
    Re: In Praise of Aethers, Baffle Studies and LEDE

    Originally posted by Andy_G View Post
    so long as its not a "bottom of the bucket" list :D
    Yeh. Gayle and I still pine for a trip down yonder. Maybe if'n I win the lottery.

    Dave

    Leave a comment:


  • dickwest
    replied
    Re: In Praise of Aethers, Baffle Studies and LEDE

    Brian,

    Thanks for your info. I have been following your system on your web site and AudioCircle.

    "Rudolf on Audiocircle helped me to understand the priciple behind using a narrowing baffle to displace the dipole rolloff to a better frequency. Here is picture of my 3 way with dipole woof, mid, tweet(2 tweeters per side). The xo points are around 250hz and 3000hz."

    I like your system and your narrow baffle. Thanks to you and Rudolf and AudioCircle I better understand this dipole peak effect.

    Later..........

    Dick

    Leave a comment:


  • Andy_G
    replied
    Re: In Praise of Aethers, Baffle Studies and LEDE

    Originally posted by dbe View Post
    I hope to, someday. There are quite a few people in your area that I would like to meet face to face. It is kind of a 'bucket list' thing.

    Dave
    so long as its not a "bottom of the bucket" list :D

    Leave a comment:


  • brianp
    replied
    Re: In Praise of Aethers, Baffle Studies and LEDE

    Originally posted by dbe View Post
    Yeah, I have. I simply have not had the time and have been using compound push/pull floor firing 12" (older Vifa drivers) subs that are pretty killer in the last 2 octaves. The problem that I was having was a slope/crossover point hump that I had a problem isolating due to the finicky nature of line level passive crossovers. When in the pf range of capacitance it gets to be a PITA to get the points just right and lumpy bass is one of my pet peeves. Of course the other thing is I don't have any woofers that fit the parameters for a dipole.

    Dave
    I suspect that trying to get an all-dipole system to behave with passive filters is beyond tricky and well-nigh onto futile. The John K and SL systems beat the problems into submission with multi-amplification, active crossovers and generous EQ. As frequency drops, this becomes more and more necessary.

    If you did want to fool with dipole woofers (H-frame, U-frame, W-frame or whatever), Danny Richie's new servo subs might fit the bill. I know he's developing something along those lines. Also, take a look at the ACI woofers that Mad just put on special. These things look like monsters, with high power handling and long linear excursion. They could be suitable, AND they're reasonably priced.

    Leave a comment:


  • dbe
    replied
    Re: In Praise of Aethers, Baffle Studies and LEDE

    Originally posted by brianpowers27 View Post
    If you are ever out in the area, stop on by. I doubt I will make it out to your neck of the woods until the kids are half grown.
    I hope to, someday. There are quite a few people in your area that I would like to meet face to face. It is kind of a 'bucket list' thing.

    Dave

    Leave a comment:


  • brianpowers27
    replied
    Re: In Praise of Aethers, Baffle Studies and LEDE

    Originally posted by dbe View Post
    Very nice. I'd love to hear them.

    Dave
    If you are ever out in the area, stop on by. I doubt I will make it out to your neck of the woods until the kids are half grown.

    Leave a comment:


  • dbe
    replied
    Re: In Praise of Aethers, Baffle Studies and LEDE

    Originally posted by brianpowers27 View Post
    Rudolf on Audiocircle helped me to understand the priciple behind using a narrowing baffle to displace the dipole rolloff to a better frequency. Here is picture of my 3 way with dipole woof, mid, tweet(2 tweeters per side). The xo points are around 250hz and 3000hz.

    The system is completely passive. The imaging is very precise.

    Very nice. I'd love to hear them.

    Dave

    Leave a comment:


  • brianpowers27
    replied
    Re: In Praise of Aethers, Baffle Studies and LEDE

    Originally posted by dickwest View Post

    The dipole peak, as I understand it, comes at higher frequencies -- depending on baffle width (narrowness). I judge the dipole peak on my baffles in the pictures above at around upper C to G (600 hz to 800 hz) and most noticeable on Diana Krall's vocal and piano notes in this range.

    I have found this effect operant with two identical similar baffles, two very similar sets of drivers, and two amplifiers of similar quality. Changes in room absorbers/diffusers can't get rid of the effect.

    Possible solutions I have found so far are to:

    1. narrow the baffle, to keep it at less than 2.2 X diameter of driver and thus drive dipole peak up to the higher frequencies where the mid/tweeter xover can handle it
    ....

    Dick
    Rudolf on Audiocircle helped me to understand the priciple behind using a narrowing baffle to displace the dipole rolloff to a better frequency. Here is picture of my 3 way with dipole woof, mid, tweet(2 tweeters per side). The xo points are around 250hz and 3000hz.

    The system is completely passive. The imaging is very precise.

    Leave a comment:

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