AudioCircle
Audio/Video Gear and Systems => Open Baffle Speakers => Topic started by: matevana on 25 Apr 2020, 04:52 pm
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(https://www.audiocircle.com/image.php?id=207823)
(https://www.audiocircle.com/image.php?id=207824)
(https://www.audiocircle.com/image.php?id=208108)
It’s been two years since the last Hestia project and there are a number of concepts I’ve been waiting to test. I plan to start building the prototypes this week and will document as the build progresses. As always, feel free to join in.
The Hestia Hybrid uses a primary full range driver mounted in an open baffle configuration with LF support from a secondary driver. It is envisioned as an alternative to well-crafted studio monitors, combining the sonic benefits of dipolar / full range loudspeakers with the manageable size and stand-alone characteristics of traditional bookshelf speakers. A compact, self-contained loudspeaker system with a modern/industrial aesthetic.
System type: A single dipole point source combined with a larger monopole up firing driver that is mounted in a tuned and damped slot loaded enclosure. Both drivers operate without a crossover.
Drivers:
Primary – Jordan Eikona II / 100mm aluminum cone
Secondary – Peerless 830869 / 8” Nomex cone
Theoretical benefits and testing objectives: (Evaluations 1-6 below).
Both drivers operate full range electrically and avoid the monopole to dipole null that would occur around a fixed crossover point. This helps maintain a symmetrical figure eight pattern associated with classic dipolar dispersion. (Eval 1).
The right angle driver coupling helps reduce frequency modulation distortion (Eval 2) and is a preferred method for combining two full range drivers.
A tuned and heavily damped front firing slot provides low frequency reinforcement that sums constructively with the dipole driver. (Eval 3).
The tuning frequency is centered at the -10dB rolloff point of the dipole driver for cohesive (non- destructive) low frequency support (Eval 4).
An adjustable driver mount is used to better align the acoustic centers of both drivers and optimize phase coherence (Eval 5).
The adjustable dipole mount provides micro toe adjustments as well as a way to help manage floor and ceiling reflections (Eval 6).
-More to come-
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I know I will enjoy what I see and read in this thread. Can't wait for more.
Thanks matevana,
JCarney
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Looks like a cool build!
When I first looked at it I pictured a 10” full range and a 15” woofer.
Is the woofer active? Also, do you think the up firing bass could effect the sound of the full range driver, particularly at high volumes?
Mike
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Is the woofer active? Also, do you think the up firing bass could effect the sound of the full range driver, particularly at high volumes?
Mike
Hey Mike,
The theory is that both drivers are passive (full range) and summing them at a right angle should be more constructive than trying to do this on the same plane. While there is no electrical crossover, the larger driver is mechanically rolled off trough a tuned slot and is heavily damped with acousta-stuff filling. When you put your ear to the slot, you should only hear low frequencies emerging from the front of the enclosure. If I did the math correctly, these low frequencies should reinforce the low end of the top mounted dipole driver. I will likely need to tweak the slot length and the amount of fill, once the test cabinets are built.
When you see the photos as the cabinets are built, it may be easier to visualize what I am trying to accomplish.
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Hey Mike,
The theory is that both drivers are passive (full range) and summing them at a right angle should be more constructive than trying to do this on the same plane. While there is no electrical crossover, the larger driver is mechanically rolled off trough a tuned slot and is heavily damped with acousta-stuff filling. When you put your ear to the slot, you should only hear low frequencies emerging from the front of the enclosure. If I did the math correctly, these low frequencies should reinforce the low end of the top mounted dipole driver. I will likely need to tweak the slot length and the amount of fill, once the test cabinets are built.
When you see the photos as the cabinets are built, it may be easier to visualize what I am trying to accomplish.
Very cool, thanks for the clarification matevana.
I’ll be watching with interest!
Mike
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The Hestia Hybrid is first and foremost an open baffle loudspeaker that uses a full range driver mounted in an open baffle. The ‘hybrid’ concept introduces a 2nd driver in a slot loaded enclosure that is primarily intended to compensate for some low frequency loss due to dipole roll-off. To accomplish this, it is necessary to tune the slot to a frequency that sums coherently with the output from the open baffle driver.
I realize this is an open baffle forum, but for the purpose of this specific project it might be helpful to share some information about slot design in an enclosure.
The tuning frequency (Fb) of the slot is a function of the slots cross sectional area (Av), its effective length (Lv), and the enclosure volume (Vb). You can replace variables and solve for unknowns using this formula:
(https://www.audiocircle.com/image.php?id=207863)
For the Hestia Hybrid, the target frequency of the slot is 70Hz, which is where the open baffle driver plays approximately 10dB lower than its average sensitivity mounted in its baffle. I am using heavy cardboard to experiment with different tunings (simulating slot length and width) before the plywood slot gets cut and installed. There may be some additional challenges in trying to couple the slot’s output to that of a dipole driver, i.e., different roll-off properties and subsequent phase abnormalities, but I am hoping to minimize this through experimentation.
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Here's some construction photos. Next on to evaluating and tuning.
(https://www.audiocircle.com/image.php?id=207918)
(https://www.audiocircle.com/image.php?id=207919)
(https://www.audiocircle.com/image.php?id=207920)
(https://www.audiocircle.com/image.php?id=207921)
(https://www.audiocircle.com/image.php?id=207922)
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Very interesting design. Looking forward to your thoughts as to how they sound
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Looking good!
And a very clever use of a grab bar.......
Mike
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Looking good! And a very clever use of a grab bar.......
LOL, Good eye! I do Procurement for a living and like sourcing materials to be used in different ways. Not only are grab bars very strong, but they float the dipole securely over the up-firing driver with plenty of room for aligning the two. It also hides the speaker wire going to the back of the dipole and makes it easy to lift and move the speaker. I'm going to use thumb wheels instead of lock nuts so adjustments can be made more easily.
(https://www.audiocircle.com/image.php?id=207949)
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A half pound of Acousta-stuff seems to yield the best output at the slot, taming any peaks in a less than optimally sized enclosure. I also tried ¼ and ¾ pounds. A mesh zipper bag holds the fill so the individual strands don’t work themselves down the back of the cabinet and into the slot.
(https://www.audiocircle.com/image.php?id=207966)
The Peerless 8” Nomex driver is no slouch. It was selected among several 8” drivers due to its flat-ish response since it will operate without a crossover. Even though the Peerless driver has higher sensitivity than the Jordan (90.2 dB 1W/1m vs. 85.2 dB 1W/1m), experience tells me that I will still have to attenuate the Jordan’s output when level matching the two drivers. In reality, I’ll be level matching the output of the slot with that of the Jordan and factoring-in dipole cancellation.
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The next and perhaps most important tuning is the forward adjustment of the dipole driver. The dipole mount allows for 5 inches of lateral travel that can be dialed-in precisely. In principle, you want the acoustic center of the dipole driver to float directly above the dust cap’s center of the up-firing driver. Finding the exact acoustic center of a driver is easier said than done. However the point from where sound originates is generally close to the voice coil. Cone drivers typically have their acoustic center closer to the back of the driver. The Jordan’s acoustic center is located in the rear third when viewing the frame from the top.
Dipole mount (rear)
(https://www.audiocircle.com/image.php?id=208002)
Dipole mount (front)
(https://www.audiocircle.com/image.php?id=208003)
This would be a straight forward adjustment if the Jordan was not mounted in an open baffle and if cancellation was not an issue. But due to the minimalist baffle, the Jordan will act more like a midrange/tweeter in this design. Because of this, it can be advantageous to compensate for the time arrival of higher frequencies at the listening position, and adjust the driver’s position to coincide with the lower frequencies coming from the slot. All things being equal, higher frequencies will arrive at the listening position earlier than lower frequencies. This can be offset by sliding the dipole driver back in relation to the up-firing driver’s center.
Using tone bursts of various frequencies, I was able to clock the arrival of the burst in milliseconds at the listening position, which in my case is 10 feet from the front of each speaker. The time difference between the average set of low frequencies and the average set of high frequencies can be represented by approximately 2 inches of rearward travel on the dipole mount. For the purpose of initial listening sessions, this will be my default setting.
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The final piece is a carpet tile inlay applied to the top baffle. This will help damp any possible reflection from the dipole driver. The front panel was cut 1/4" oversize so the inlay sits flush from the front.
(https://www.audiocircle.com/image.php?id=208109)
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And here's the finished project and stand detail. My preferred listening height is having the full range driver slightly higher than ear level when seated.
Once the shiny new toy syndrome passes, I'll post some listening impressions.
(https://www.audiocircle.com/image.php?id=208117)
(https://www.audiocircle.com/image.php?id=208118)
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Nice, Kinda looks like a Gradient without the sloped Mid. Enjoy looking VG.
charles
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Looks very good and, aside from the Jordans, it looks to be a pretty inexpensive build.
Is the box about 13-14" cubed? I'm trying to get an idea of the overall size.
Looking forward to your listening impressions.
Mike
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Nice, Kinda looks like a Gradient without the sloped Mid. Enjoy looking VG.
charles
I got to see Gradient's Helsinki in-person. They actually use sheet glass as part of the design which I think is very creative. I imagine it would be like owning a piece of art and a great conversation piece. The finish was also top notch.
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Looks very good and, aside from the Jordans, it looks to be a pretty inexpensive build.
Is the box about 13-14" cubed? I'm trying to get an idea of the overall size.
Looking forward to your listening impressions.
Mike
One of the cool things about the dipole baffle being so minimalist is that you can have several and swap drivers in minutes. There are several good full range drivers in the 4-6" range (Tang Band, Fostex, Seas, etc.) that should work well in this design. I'd be more concerned about substituting for the Peerless driver, as you essentially need a woofer that will play politely without a crossover and in my experience there are few. The Seas H1411 is another woofer that should work but is slightly larger at 10" It is designed to be used in Dynaco A25 replacements, which also did not use a crossover.
The cabinet is actually only 12" x 12" x 12". It has a net internal volume of about .70 cubic feet. It looks larger in the photos than in real life.
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How much of the theory of this is like the LXMini? I use those as my main speakers and they are incredible. These look very similar.
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How much of the theory of this is like the LXMini?
They are probably more different then they are similar. They both share the right angle coupling of two drivers to minimize frequency modulation distortion. I have not heard the LXMini, but I am a big fan of the larger LX-521. Here’s where I believe they differ: The LXMini operates as a cardioid over part of its frequency response, relies on electrical crossovers and correction from digital signal processing, requires 4 channels of amplification, and can be subject to pipe resonance if not constructed properly. They also may have less dynamic impact due to the small-ish drivers that are used (just physics).
The Hybrids are true dipole loudspeakers, as they operate with dipolar radiation throughout their frequency response similar to the LX-521. There is no electrical crossover on either driver (phase shift), no need for digital signal processing and are driven by a single stereo amplifier. The drivers are larger and can handle more excursion (higher SPLs) before distortion becomes audible. I wanted a system that allowed <source -> amplifier -> speakers> and nothing else in the chain. The Hybrids can also be placed like a bookshelf speaker, provided they have sufficient distance from walls and significant boundaries. (The stand is not an integral part of the design the way it is with the LXMini).
While I like the Linkwitz designs, I am not a fan of the MiniDSP that is often used with the speakers. With the LX-521 that I heard, I much preferred the ASP (analog signal processor) option as I didn’t feel like the ASP became the limiting factor in the design. Of course, the ASP was more expensive by comparison.
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What sort of amp are you using to drive these?
I have a set of the Eikona II's that I was putting in a small TL cabinet, but it would be interesting to try this out. Just need the two peerless drivers an a bit of MDF for the base cabinet. Interested to hear how you like them.
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What sort of amp are you using to drive these? Interested to hear how you like them.
I use a Digital Amplifier Company Stereo Maraschino amplifier. It's a class-D amp with just 2 balanced inputs, a passive volume pot, and speaker outputs.
I have used the Jordans in several configurations and have always liked them. After several years I feel like I know them well and can assess the pros and cons of enclosure changes effectively. I plan to do a lot of listening this weekend and then write some impressions.
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Listening Impressions, 5/3/2020
Room: 14’ x 19’ with 8’ ceilings / average brightness / no room treatments
Equipment:
Speakers: Hestia Hybrid dual full range – open baffle / tuned slot
Source: Sony NW-ZX300 Digital Audio Player
Amplifier: Digital Amplifier Company Stereo Maraschino / 60v DIY power supply
Interconnect: LQi Cables, Balanced 4.4mm TRRRS Sony connector to Dual XLR / Silver coated copper
Speaker Wire: Western Electric cloth covered copper, 14 AWG, circa 1950, 8 ft. sections
Evaluation Material:
Iiro Rantala & Ulf Wakenius, Good Stuff, 2017, 96kHz FLAC
Deep Purple, Perfect Strangers, 1984. 44.1kHz AIFF
Gyorgy Cziffra, Liszt: Hungarian Rhapsodies, 1975, 44.1kHz AIFF
Nicki Parrott, Stompin’ at the Savoy, 2018, 44.1kHz FLAC
Denis Matsuev, Shastakovich: Piono Concerto No. 1, 44.1kHz FLAC
Technical Observations:
These are the most phase coherent speakers I have owned. Even though they use two distinctly different drivers they seem to mesh seamlessly. The sound arrives at the listening position completely in-tact, regardless of the complexity of the musical track. This was not the case when the same drivers were mounted on a single flat panel. Also interesting is the much wider sweet spot compared to the prior iteration.
This improvement is likely a result of three things. (1) Combining two drivers on separate planes, while maintaining the alignment of their acoustic centers; <the combination of direct sound from the dipole driver along with the more omnidirectional radiation of the up-firing driver seem to trick the brain into hearing a single point source throughout the full frequency response>; (2) Crossover-less systems do not add additional phase shift or time anomalies; (3) the ability to mechanically adjust the arrival time of the higher (faster moving) frequencies at the listener’s position.
What surprised me most was the significance of the Peerless driver in this design. I originally envisioned the up-firing driver to be more supportive in nature as it was in the flat panel design. In reality though, it is a major contributor to the Hybrid’s overall sound.
Contrary to the above, it seems that the Hybrid’s character is more reminiscent of the Jordan Eikona. It’s interesting that when you disconnect the Peerless driver, the image completely collapses. The Jordan in its minimalist baffle is incapable of supporting full range listening to anything other than the near field, but it helps to set the table for the Hybrid’s overall character. I am very familiar with the Jordan in a large baffle, as they (along with an active sub) have been my main speakers for the past few years. The illusion created by both drivers in tandem has me believing that I am listening to a single much larger driver, without sacrificing any of the Jordan’s smooth sound and superior dispersion. .
I mentioned during the construction stage that I expected to have to attenuate the Jordan driver after factoring-in dipole cancellation in order to match the slot’s output level. 9.5 ohms of resistance ended up being the perfect amount. This was achieved by combining a 27 ohm and 15 ohm Mundorf M-Resist resistor in parallel. The parallel resistance also allowed for more power handling. Substituting dipole drivers would require an adjustment to the amount of added resistance.
The slot does an excellent job of adding low frequency weight to the dipole driver in a manner that was never possible with my flat panels + subwoofer. I am particularly referring to bass quality over quantity. Perhaps this is a function of the better electronics associated with a main amplifier compared to that of a plate amplifier, the fact that the input signal is not split, or the slot’s proximity to the other drivers, but the level of coherency is a marked improvement. The amount of low frequency energy is similar to that of like-sized bookshelf speaker. It would be an easy task to integrate a sub below 60Hz, but for now I am enjoying them solo.
I should mention that I made a design change regarding fill and the resulting bass quality. I have used Acousta-stuff in prior sealed cabinets. However the bass in the finished design sounded more constrained than what I was hearing during the initial construction without any fill. There may have been too much absorption taking place prior to reaching the slot. Instead, I lined each adjacent interior wall with carpet tile and scrapped the Acousta-stuff entirely. This eliminated the constrained character and changed the bass presentation to a more natural wet/dry balance.
So how do they sound?... really.
Good. Really good in fact. I usually start to notice shortcomings once the newness wares off. Maybe that’s why I’m not married. But so far I am thoroughly enjoying them.
Personally I am more sensitive to phase shift than other design challenges. This was a major consideration in the Hybrid’s design. I am very pleased with the outcome. This may explain why I am a fan of well-designed full range drivers and no crossover. Their primary downside (higher intermodulation distortion) is offset here by a properly integrated second driver allowing for higher system SPLs, with each driver doing less of the work. The Jordan’s 4” cone is also less prone to beaming than larger full range drivers.
The timbre produced by the Jordan/Peerless mashup is very realistic. The sparkle around a piano’s highest octave is excellent, as is the tone of brass instruments. I attribute this to the Jordan’s metal cone and proprietary phase plug design. I have not detected any noticeable lobing in the design. The Peerless brings warmth and weight to the party. Although it is designed primarily as a woofer, it has a fairly smooth natural roll-off at higher frequencies and is not shamed by the lack of a crossover, especially in an up-firing alignment. The Jordan, while being a very capable driver, is essentially a 4“ speaker and cannot be expected to move the amount of air necessary for the lowest registers in an open baffle setting. Together they not only mitigate each other’s shortcomings, but create a synergy where tone is concerned.
As mentioned earlier, the sweet spot has grown significantly compared to the same drivers being mounted in a single flat panel. This has not impacted imaging adversely. The spatial location of musicians are well preserved, and depth perception seems to have increased over prior iterations. The width of the soundstage in my room is consistent with prior designs, and was not compromised by the up-firing driver.
If I had to find fault with the Hybrids it would involve low volume listening. This is my first slot loaded design and it may be a quality of the slot itself, compared to other types of vented designs. I have noticed that slots seem to require a decent amount of air to pressurize the room. They really excel at average listening levels and beyond, but there is a notable drop-off of low frequency energy at reduced volume. I should mention that my amplifier does not have a loudness function or midnight mode, and perhaps this might help. For a number of reasons, I do not suggest substituting a conventional port tube in lieu of the slot with this particular design.
Several people contacted me about the high cost of the Jordan Eikona 2, and asked if I could recommend a lower cost alternative that would be successful in this design. I have no reason to believe that the Hestia Hybrid would not excel with a variety of full range drivers. Due to the concern over beaming, I would suggest keeping the driver as close to 4” as possible. This will also help preserve the off-axis response. The dipole’s total Q (Qts) is less of a factor here, as this driver functions primarily as a mid/tweeter due its small baffle size.
All things considered, I would definitely recommend this design to anyone interested in exploring open baffle speakers, without the added complexity of having multiple amps, digital signal processing and crossovers.
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Thanks for the detailed write up. I am interested in trying this in the future. I may even have enough 3/4” MDF to build the boxes.
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An Interesting Variation
(https://www.audiocircle.com/image.php?id=208656)
Flipping the larger driver so it fires into the cabinet makes for a thought provoking variation on the design. A little less low frequency energy emerges from the slot, but the mid frequencies radiate out into the room more prominently. You can compare this to the directionality of a guitar string as opposed to a typical speaker baffle. You must remember to invert the polarity of the larger driver to maintain a positive phase relationship between the slot and the dipole driver.
I only tried this with one speaker so I can’t comment on how accurately these might image, but I would expect them to throw a wide (almost exaggerated) sound stage. In my situation I plan to listen without subs, so I did not fully explore this variation.
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Matevana,
Hi, I was referred here from a post of mine over on tech/talk.
I have questions.
You need to know I am just beginning my audio adventure. As a woodworker, I have been seeking something different to build, and as a music junkie, this fits a lot of my needs.
Hybrid open baffle, and omission of crossover design/build, chief among them.
I wonder if I might pick your brain a bit?
I have some GRS BOFU clones. I know nothing of their specs, and even though I know the specs are available, I have no idea what I'm reading, so you need to read this as though a child were writing it.
My main question is, do you suppose I could realize similar results using the BOFU clones, and another, preferably inexpensive driver? I.E. for the 4"-6" full range on top?
The slotted enclosure is 12"x12"?
How tall is the slot? Looks to be about an inch?
Anything you would change or add/subtract in the design or fabrication
of the enclosure?
Regarding the D-class amp , is this off the shelf?
Would one of the mini amps (d-t class) power these sufficiently enough using a phone streaming Spotify as source?
Sorry for the artillery barrage of questions. I'm new, and as I mentioned, just joined up to address you about these speakers, though I'm totally sticking around. (Verification gauntlet appreciated but tiresome.)
Lol
Anyway, thanks in advance, these look pretty stellar. I hope I can get close to the quality sound you describe, if even on the very cheap!
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One more request....lol....sorry.
Any chance of getting dimensions? True box size, slot size, size of interior baffle and it's distance from the back wall of the interior?
EDIT to add (sorry)
The raw size of the Jordan's baffle prior to cutting the driver's radius as well as the handle bar sizing/source would be pretty important I think .
Looks like I'm going to give these a try
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Matevana,
I have questions.
My main question is, do you suppose I could realize similar results using the BOFU clones, and another, preferably inexpensive driver? I.E. for the 4"-6" full range on top?
The slotted enclosure is 12"x12"?
How tall is the slot? Looks to be about an inch?
Anything you would change or add/subtract in the design or fabrication
of the enclosure?
Regarding the D-class amp , is this off the shelf?
Would one of the mini amps (d-t class) power these sufficiently enough using a phone streaming Spotify as source?
Sorry for the artillery barrage of questions. I'm new, and as I mentioned, just joined up to address you about these speakers, though I'm totally sticking around. (Verification gauntlet appreciated but tiresome.)
Lol
Anyway, thanks in advance, these look pretty stellar. I hope I can get close to the quality sound you describe, if even on the very cheap!
Hi and sorry for my delayed response. I'm usually pretty prompt. :)
Would you be able to provide the part number for the GRS woofer that you already have? I'm sure we can find an inexpensive small full range driver that will work well in combination.
The enclosure's outside dimensions are 12" x 12" x 12" and the walls are all 3/4" MDF. That makes the internal volume right around .7 cubic feet.
The slot height is 3/4" and it's depth is 8". We may have to change the dimensions slightly to tune for the GRS woofer. The slot height and depth determines the cabinet's tuning, similar to a cylindrical port tube in a typical vented speaker.
If you are planning to have the speakers sit on a shelf or table, I would leave the slot as-is. If you are planning to use stands, I would be tempted to move the slot's mouth to the top of the front enclosure wall, leaving the woofer where it is. You can do this by orienting the slot so it runs vertically along the front panel. I can provide a drawing if this interests you.
My particular amplifier is made by a company called Digital Amplifier Company, but any decent stereo amplifier should work fine. The amp should be able to drive a 4 ohm load, which should be no problem for most solid-state amplifiers and even some tube amplifiers.
The baffle that supports the full range driver will be the same width as the widest dimension of that driver. It's as minimal as possible in this design. The center of my particular driver is suspended 7" above the top of the enclosure.
The grab bar is made by Kohler and it is a 12" model with exposed screws on the mounting flange (you want this). Most grab bars have a more finished sliding bezel that hides the screw holes which will not work in this application. It measures around 15" from the furthest point of each mount. It is stainless and the tube diameter is 1 1/4".
Please let me know which GRS model you have and I can make some recommendations.
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An Interesting Variation
(https://www.audiocircle.com/image.php?id=208656)
Flipping the larger driver so it fires into the cabinet makes for a thought provoking variation on the design. A little less low frequency energy emerges from the slot, but the mid frequencies radiate out into the room more prominently.
Hi Matevana! Why is there less low frequncy with the inverted orientation? Or do you mean less in relation to the elevated mids?
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Hi Matevana! Why is there less low frequncy with the inverted orientation? Or do you mean less in relation to the elevated mids?
That’s a great question Jonas.
Here’s some speculation on my part, which may just come down to physics (efficiencies and losses).
The Fb of the box (frequency at which the slot is tuned) relies on three factors, two of which are fixed in either case (the length/cross sectional area of slot and the speed of sound in air). That leaves the third factor which will vary depending on the orientation of the driver.
Factor #3 is the internal volume of the enclosure, which was previously measured taking into consideration the driver’s displacement. By inverting the driver, you are effectively increasing the enclosure’s volume and a loss of optimization will result based on the existing tuning. Since the enclosure is small to begin with, this change in apparent volume is not insignificant and measurable losses will occur compared to a fully optimized system.
That being said, if the initial parameters had included the increased volume from inverse mounting, and the slot dimensions were altered accordingly, there should be little difference.
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That’s a great question Jonas.
Here’s some speculation on my part, which may just come down to physics (efficiencies and losses).
The Fb of the box (frequency at which the slot is tuned) relies on three factors, two of which are fixed in either case (the length/cross sectional area of slot and the speed of sound in air). That leaves the third factor which will vary depending on the orientation of the driver.
Factor #3 is the internal volume of the enclosure, which was previously measured taking into consideration the driver’s displacement. By inverting the driver, you are effectively increasing the enclosure’s volume and a loss of optimization will result based on the existing tuning. Since the enclosure is small to begin with, this change in apparent volume is not insignificant and measurable losses will occur compared to a fully optimized system.
That being said, if the initial parameters had included the increased volume from inverse mounting, and the slot dimensions were altered accordingly, there should be little difference.
Thanks for a great reply. That was also the only explanation I could think of, just wanted to check that I haven't missed any fundamental knowledge! :green:
Btw, love your "simple" but ingenious designs!
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Matevana has a wonderful way of explaining concepts to a fledgling like me.
Great info in his builds. Always take something from his posts.
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Hi Matevana,
interesting project! Can I ask a question?
You say the Jordan's output will be down by ~10db at 70Hz, is this from measurement or calculation?
Thanks for sharing,
Ian
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Hi Ian,
When I measured the Jordans for the Univesals' project ( https://www.audiocircle.com/index.php?topic=154866.0 (https://www.audiocircle.com/index.php?topic=154866.0) ) there was a 10dB difference at 70 Hz in open air. The baffle used in the Hybrid project won't prevent much cancellation so it will likely be about the same; in this design the baffle mostly supports the dipole driver and provides some forward reflection for the upfiring driver. When my university eventually reopens, I will have better access to a measurement room.
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Hi Matevana
I have been contentedly listening to the Hestia Vs for several years. Lately though my audio buddies have been building this and building that, so here I am. I would like to build the hybrids unless you have something else in development. At this point I am just gathering parts and have a few questions.
I bought a pair of Mark Audio Alpair 11 MS Gen 2 full rangers and have been looking for woofers. The Peerless have been discontinued and while I still see a few on Ebay I have been looking around. The Dayton Audio RS225-8 8" caught my eye. I am not sure of all the parameters you are using to pick the woofer, but am wondering if these would be good candidates?
Secondly, I am wondering about the enclosure size. I believe you are using the Denovo flat pack. It seems a little small compared to PE's recommendations for both the Dayton and the Peerless in an unsealed application. Does the enclosure size make a big difference with the hybrids?
Thank you as always for your advice.
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Hey SJHomey,
Placing the Peerless in a smaller than optimal enclosure provided the necessary upper bass hump I needed to create a flat-ish response with the Jordans. It was a balancing act between the FR drivers roll-off, the increased sensitivity of the woofer (compared to the FR driver) coupled with the above mentioned hump, and the low output from the port. When I was experimenting with the hybrids it became clear that all of these things were interrelated, maybe more so than in a conventionally aligned speaker with all the drivers on the same plane. Updating one typically required adjusting the others.
A few things to keep in mind.
The Jordan is essentially a 4” driver while the Alpair 11’s are closer to 6.5”. The larger Alpair with an appropriately sized baffle/mount will have a different roll-off. In this case you likely don’t want the same upper bass hump I was seeking, or you might want it centered at a lower frequency. If the Alpair is more sensitive, you will also want to select a more efficient woofer. You will need the extra headroom to address the Alpair’s LF cancellation.
I’m sure you saw that the Denovo flat pack in question is a sealed box. If you choose to start with that, you will need to modify the box if you are mimicking the Hybrid’s slotted design.
I have experimented with a few newer designs, none of which are better than the Hybrids. If I were to redo the Hybrids today, I might move the port from the bottom to the top (also front facing). The port’s closer proximity seems to couple even better when all three sound waves essentially originate from the same plane. (I’m including the woofer’s reflected output against the FR driver’s baffle in the “same plane” reference).
Hope that helps and feel free to PM as needed.
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Hello Matevana!
I really like the simplicity of this design. Any comparisions to LX521?
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I built the upper part Mcm/Vifa some years back and brought them down from the attack a couple days ago. Going to run them along with my Overnight Sensations for now. The Hestias bring in some pleasing midrange while the modest but musical base from the OS's complete the party. Was considering adding a Klipsch 10" powered SW at some point. It would be placed on the floor between the Hestias. This is only for music ( not John Wick ). the hestias will be about 12 feet apart. Do you think the SW would integrate o.k. this way? I will run all this at modest volumes.
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Hi Motosapien,
Just so people don't get confused, I believe you are asking about the original Hestia design? (you are posting in the Hybrid thread currently). If so, the originals are fairly easy to integrate with most subs and what you are asking about should be fine. The Hybrids require a little more care when choosing a sub.
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Hello Matevana!
I really like the simplicity of this design. Any comparisions to LX521?
Hi szach00,
Unfortunately I only got to hear the LX521's at a show, in a really poor room. I have much more quality ear-time with the Orions, which I thought were great.
The Hybrids can offer sound staging similar to some Linkwitz designs but have a scaled down presentation, more like that of a classic British studio monitor. They are well balanced for their short stature, but can't come close to the almost perfect octave to octave balance and strong dynamics of the LX521, or even the Orion for that matter.
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Hi Motosapien,
Just so people don't get confused, I believe you are asking about the original Hestia design? (you are posting in the Hybrid thread currently). If so, the originals are fairly easy to integrate with most subs and what you are asking about should be fine. The Hybrids require a little more care when choosing a sub.
Thanks for the reply M. Sorry about being in the wrong thread. And thank you for the original design!
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I am in the process of finishing up, with Matevana's very generous advice, a version of this design with different drivers. They are up and running and sound very good. I have built three of the Hestia versions and this is by far the best. Amazing detail and invisible.
I am using Markaudio Alpair 11 MS Gen2 full range drivers instead of the Jordans. They are considerably less expensive, but have a well respected reputation, with which I fully agree. Over 6", they are much larger than the Jordans. The Alpairs are paired with Hi-Vi Research E8 8" woofers. I used a Denovo 12" flat pack C&Ced box. At present the woofers are driven by inexpensive plate amps from a previous built, hence the wires running through the slot. I modeled the slot in Winisd and according to the modeling should play down to 55 hz. or so. Plenty of bass. Eventually, I will replace the plate amps with a proper crossover and drive them with my higher quality amp.
This build is not much different from what Matevana has laid out. At his suggestion I moved the slot from the bottom to the top of the box, as pictured, to bring the sources of sound closer together.
While still very much in the process of tweaking these speakers, they sound amazing. There was a fair amount of work to be done to modify the boxes but being C&Ced they glued together very nicely.
While I am not a bad fabricator, design and principles of speaker design are way beyond me. I so much appreciate Matevana's knowledge and willingness to share.
(https://www.audiocircle.com/image.php?id=261012)
(https://www.audiocircle.com/image.php?id=261013)
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@sjhomey,
Very cool. Very much my style.
I like how you used the bolt on bar/towel rack to hold the upper portion.
And the sub mod, again very cool.
Wayne in Oregon