In Praise of Aethers, Baffle Studies and LEDE

[dickwest]

Still waiting to receive an Aethers kit

Over a week ago I paid Christianb for his Aethers kit which he said he would send last Monday, or Tuesday at the latest. Then he told those of us who are purchasing stuff from him that we would get tracking numbers for items over the weekend and he would ship everything today.

http://techtalk.parts-express.com/sh...48#post1579548

Still have heard nothing from him. I sure wish he would hurry up. He is a week late in responding!

The comparison between my version and the "real" thing awaits and I am anxious to complete this stage in my speaker hobby career .

[christianb]

Re: In Praise of Aethers, Baffle Studies and LEDE

Check your PMs, I sent you the tracking! :D

Seriously, to you and everyone else, I'm really sorry it took longer than expected to get everything out. Things just didn't go too well for me this week with work and the baby.

[dbe]

Re: In Praise of Aethers, Baffle Studies and LEDE

Andy,

The 2nd picture in the 2nd post is the 2nd version of OB speakers I tried. This 2nd version uses the Audax HP130Z2 drivers. Here you can see my comments about this driver plus comments from John Krutke about them as well (http://www.diyaudio.com/forums/showt...threadid=55456). The HP130Z2 was never available retail as far as I know. They showed up in eBay auctions after, I believe, a certain large speaker manufacturer in the Los Angeles area went bankrupt and I snagged a few pairs of them. These are really great mid drivers but their Fs is a little higher than that of the HM130ZO so they lack a little of the lower midrange in my application.

Yes, I tried putting a "lid" on the "U" shaped baffle in the 2nd picture (2nd post) and sensed a slight reduction in the image size and concluded I did not like it.

Note the 2 different shapes of baffles and my comments about which is preferred, at least in my application.

Hi, Dick.

One of the things that I have a love/hate relationship with is the room interaction of an open baffle/dipole speaker. Couple this with the sensitivity of the driver location on the baffle and there are a zillion combinations possible for image size, depth and specificity. Pretty cool how one can tailor the image to the recording though. This works great with small jazz combos and chamber music recordings and the like. Mine are FE206 Fostex that I'm jacking with to see if I can come up with a full range(ish - > 150Hz) driver that works for me. They are out of the listening room for now. I'll get back to them in a month or so... too many other projects. Besides, I'm having a hard time finding a woofer module that blends well with the Fostex OB.

Looks like you are having fun with the challenge and that is what this is all about - enjoying the music and the hunt for it, right?

BTW - I never did get the 41Hz amps to sound right in my system: too much noise.

Dave

[brianpowers27]

Re: In Praise of Aethers, Baffle Studies and LEDE

Hi, Dick.

One of the things that I have a love/hate relationship with is the room interaction of an open baffle/dipole speaker. Couple this with the sensitivity of the driver location on the baffle and there are a zillion combinations possible for image size, depth and specificity. Pretty cool how one can tailor the image to the recording though. This work

I hear that a dipole mid matched with a monopole woofer typically has more challenges matching the power of the mid to the woofer, given different room setups. I found that my nearly "true" dipole can travel from room to room merrily.

I really do think everyone owes it themselves to listen to an OB in their listening environment. It may not be your cup of tea but it is worth experiencing.

[dbe]

Re: In Praise of Aethers, Baffle Studies and LEDE

I hear that a dipole mid matched with a monopole woofer typically has more challenges matching the power of the mid to the woofer, given different room setups. I found that my nearly "true" dipole can travel from room to room merrily.

I really do think everyone owes it themselves to listen to an OB in their listening environment. It may not be your cup of tea but it is worth experiencing.

Yep, dipoles are fun to listen to, for sure. Very spacious and appealing.

The problem that I'm having is not really a speaker problem, but a crossover problem. I used a line level passive crossover between the preamp and amps and it just didn't cut the mustard - more of an amp integration than speaker integration issue. I'll be trying a different approach after I build kitchen countertops. Priorities........................

Dave

[dickwest]

Re: In Praise of Aethers, Baffle Studies and LEDE

Brian/dbe,

I agree that the integration of a dipole bass with an OB mid/tweeter is a challenge. It may be simple to do, as in the Aethers, but I am finding an unexpected complexity in managing power into the room at certain frequencies.

So far my research tells me that not only must one be aware of baffle rolloff (from cancellation of wrap around frequencies) but there is the "dipole peak" that many ignore or are willing to tolerate. The dipole peak, as I understand it, comes from the point where frequencies create sound waves of lengths that cause a summation as the back and front waves combine.

Cancellation at the low end of the midrange can be handled by boosting/equalizing sound at 6db from the dipole cancellation point on downwards.

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

2. stuff the back side of the driver, especially around the basket, to dampen energy at these frequencies

3. apply notch filters based on measurements of driver/baffle combos.

It is reasoned that bass boost on the low end is simpler to do than designing/applying notch filters to the mid bandpass filter, and an open mid baffle is a simple thing to construct.

The excitement of an open baffle midrange does come with a price in increased, not decreased, complexity. Here are some posts at Audio Circle that speak to these issues.

http://www.audiocircle.com/index.php?topic=64048.40

My next iteration of the mid baffle will be more narrow and slightly triangular in shape -- to raise and broaden the range of dipole peaking and thus make it less obvious, and generous use will be made of an Alesis M-EQ230 1/3 octave equalizer to boost lower frequencies.

Any suggestions/help to fashion a relatively simple approach to make Diana Krall's certain notes better mesh with the rest of her sound? I'm not seeking perfection here, in the spirit of the Aethers, but hope better to match certain parts of the mid range with the rest of the bandpass.

Dick

[brianp]

Re: In Praise of Aethers, Baffle Studies and LEDE

Besides, I'm having a hard time finding a woofer module that blends well with the Fostex OB.

Dave, have you thought about using a dipole woofer? One thing Kreskovsky and Linkwitz have been emphasizing for a long time, is that it will blend MUCH better with a dipole mid than a monopole woofer can.

[dbe]

Re: In Praise of Aethers, Baffle Studies and LEDE

Dave, have you thought about using a dipole woofer? One thing Kreskovsky and Linkwitz have been emphasizing for a long time, is that it will blend MUCH better with a dipole mid than a monopole woofer can.

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

[dbe]

Re: In Praise of Aethers, Baffle Studies and LEDE

Brian/dbe,


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.

Any suggestions/help to fashion a relatively simple approach to make Diana Krall's certain notes better mesh with the rest of her sound? I'm not seeking perfection here, in the spirit of the Aethers, but hope better to match certain parts of the mid range with the rest of the bandpass.

Dick

Dick,

I just do not know enough about dipoles to be of much help here, but I have been surprised by the sensitivity of the driver on the face of the baffle board to both diffraction anomalies and MR coloration. It is pretty easy to see the peaks and valleys on freq plots, but harder to sort it all out due to the windowing of the direct radiation and the unmeasured room contribution that helps to create that "dipole sound". I haven't spent enough time measuring and extrapolating that data to figure out all that is going on.

I would do some very simple baffle configuration changes with duct tape, foam board and 1/4" MDF to see what different configurations do. I did find that I preferred a baffle with 30 degree swept back wings to a flat baffle, though. They are assymetrical in size - 6" wide on the outside and 10" wide on the inside. The central portion is 8-1/2" in width and is 48" high with the driver centered at 37" off of the floor. The subs are directly behind the baffles.

Let me know what you learn. I will get back to the project in due time. This is a steep-ish learning curve for me.

Dave

[brianpowers27]

Re: In Praise of Aethers, Baffle Studies and LEDE

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.

[dbe]

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.

Very nice. I'd love to hear them.

Dave

[brianpowers27]

Re: In Praise of Aethers, Baffle Studies and LEDE

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.

[dbe]

Re: In Praise of Aethers, Baffle Studies and LEDE

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

[brianp]

Re: In Praise of Aethers, Baffle Studies and LEDE

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.

[Andy_G]

Re: In Praise of Aethers, Baffle Studies and LEDE

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