New Build: Hestia-SL

0 Members and 1 Guest are viewing this topic. Read 46159 times.

sjhomey

  • Jr. Member
  • Posts: 39
Re: New Build: Hestia-SL
« Reply #20 on: 16 Dec 2012, 10:23 pm »
No, no, tell me it ain't so. Relegating my beloved (and cheap) MCM 55-2981 to a has been? So sad.

On another note I wonder about vibration from the low mid. I have quite a bit of baffle vibration on my Hestias. All three drivers are isolated from the 1 1/2" baffles with gasketing tape. The frames are relatively still but the baffles pick up a fair amount of vibration. Maybe it is the cumulative effect of the end of the dog's wagging tail but I feel most of it at the top adjacent to the mid. It appears to be originating from the mid. I wonder if further isolating the lower mid on the SLs might warrant a consideration. I'm sure I'm getting ahead of the design process once again, but I thought I might just mention it for consideration. I know vibration is a no-no. I don't know how much is acceptable.

This is not to criticize the Hestias which I think sound great.

matevana

Re: New Build: Hestia-SL
« Reply #21 on: 16 Dec 2012, 11:55 pm »
No, no, tell me it ain't so. Relegating my beloved (and cheap) MCM 55-2981 to a has been? So sad.

On another note I wonder about vibration from the low mid. I have quite a bit of baffle vibration on my Hestias. All three drivers are isolated from the 1 1/2" baffles with gasketing tape. The frames are relatively still but the baffles pick up a fair amount of vibration. Maybe it is the cumulative effect of the end of the dog's wagging tail but I feel most of it at the top adjacent to the mid. It appears to be originating from the mid. I wonder if further isolating the lower mid on the SLs might warrant a consideration. I'm sure I'm getting ahead of the design process once again, but I thought I might just mention it for consideration. I know vibration is a no-no. I don't know how much is acceptable.

This is not to criticize the Hestias which I think sound great.


Hey Peter,

Yeah, it was difficult decision to make. The original Hestia's were designed to be more laid back and I couldn't be happier with the MCM's in that app.  The Hestia-SL's are all about resolution and absolute detail; the MCM's just lose that lower mid clarity when crossed to the Celestion coupling driver.

Regarding vibration on your Hestias, I can think of a couple of things to try.  First, your baffle dimensions are different, with greater open space between the upper and lower MCM drivers. That extra space could be acting as a bit of a sound board. If you believe it to be coming from the upper mid driver, try to limit it's excursion instead of allowing them to roll off naturally. An easy way to do this is with the use of a Harrison Labs FMOD inline crossover. (Parts Express) They are small passive inline RCA filters that go directly before your amp's inputs. You can try the ones that block frequencies below 100Hz. That will greatly eliminate the drivers moving mass up top, and hopefully make a big difference. Since your lower drivers are handling sub duties anyway, it may clean up the sound a bit from previously overlapping drivers.

Alternatively, if you are using an A/V receiver as your main amp, try working with it's internal crossover to roll-off the mid driver a bit in a similar manner.

Lastly, in looking at your photos, you may be able to deaden the aforementioned "sound board" area by bracing the top third of the baffle from the back. Those industrial c-channel shelving standards screwed in from the back into the meat of the baffle should do the trick. I'm specifically referring to the steel standards that accommodate double wide shelving brackets similar to what you might see in a garage. You can use a rubber gasket between the standards and the baffle back where they come in contact. Often a thinner baffle reinforced with c-channel will resonate less than a thicker baffle without.  C-channel of this caliber will not warp over time and should hold the baffle taut.

Redefy Audio

  • Industry Participant
  • Posts: 116
Re: New Build: Hestia-SL
« Reply #22 on: 17 Dec 2012, 01:06 am »
interesting!!

what would be other alternatives for the 10" pro woofer? is this mandatory? i mean size and sens?

henry

matevana

Re: New Build: Hestia-SL
« Reply #23 on: 17 Dec 2012, 01:00 pm »
interesting!!

what would be other alternatives for the 10" pro woofer? is this mandatory? i mean size and sens?

henry

The SL design relies on the careful matching of drivers and their efficiency, as there is no need for additional EQ or compensation. The larger than average 10" mid driver is needed to flesh-out the lower mids that would otherwise roll off due to cancellation, when used with a smaller than average LF driver, which too is part of the unique alignment of this design. Other pro sound drivers may work well, with an average sensitivity of around 95dB and a total Q approaching .5.  Anything less and you will likely need to biamp (or even triamp) the design. The driver must also be well defined in the upper bass / lower mid range, or it will not properly mesh with the very articulate midrange coupling driver. The previously used MCM drivers excel in the lowest octaves, but can really lose coherence in the upper registers. This becomes more obvious when mated in a 3-way design.

sjhomey

  • Jr. Member
  • Posts: 39
Re: New Build: Hestia-SL
« Reply #24 on: 17 Dec 2012, 02:22 pm »
matevana

Would that be the Dayton Audio PA255-8 10" Pro Woofer? The price isn't too bad.

I'll look into C channel on the back of the Hestias. That is a good idea.

matevana

Re: New Build: Hestia-SL
« Reply #25 on: 17 Dec 2012, 04:06 pm »
matevana

Would that be the Dayton Audio PA255-8 10" Pro Woofer? The price isn't too bad.

I'll look into C channel on the back of the Hestias. That is a good idea.

You are correct sir!  Not a bad driver for the money. Just wish it had that nice aluminum cast frame that the MCM sports.

matevana

Re: New Build: Hestia-SL
« Reply #26 on: 22 Dec 2012, 05:14 pm »




Lots of testing going on. The isolation mount seems to work well. Lots of component value swapping and critical listening. Test baffle dimensions in 3/4" MDF images well. This is now the 3rd baffle design and each have affected the off axis response primarily. The 3rd iteration appears to work best to date. I now have a new favorite tweeter, namely the VIFA XT19.

matevana

Re: New Build: Hestia-SL
« Reply #27 on: 22 Dec 2012, 05:45 pm »
A closer pic showing baffle shape iteration #3, 12/21/12:




matevana

Baffle #4
« Reply #28 on: 27 Dec 2012, 09:37 pm »
And after another 20 hours of listening, it's on to baffle iteration #4. Since the Hestia-SL design doesn't use any active compensation for the top three drivers, the nude-like baffle around the mid just wasn't cutting it. A bit too much cancellation. A complete baffle redesign was necessary in order to provide more baffle "real estate" around the mid driver, while maintaining the desired imaging characteristics.  In a mock-up made of Masonite, this baffle shape made a big difference. The actual baffle will be cut from 1" spruce. Since there isn't a lot of excess meat on the baffle, the driver's frames mounted with 1" screws will help keep the baffle rigid. I also noticed that softer/thicker woods actually do a nice job in absorbing certain resonances, despite what one might think.

A few more crossover component changes and it'll be about 90% there.

The original Hestia design to the left is being built for my neighbor. He actually spent a lot of time bringing CD's by to hear them. Every time he thought he could stump the design he just laughed, shook his head and went back to his $1500 pair of boxed speakers. He soon will have his own pair, at about one tenth the cost.  :thumb:





   

matevana

Re: New Build: Hestia-SL
« Reply #29 on: 28 Dec 2012, 03:00 pm »
Huge progress in the past 24 hours. The extra baffle width was exactly what was needed. The results are quite measurable keeping all the other parameters in tact, even the exact baffle position relative to the rear wall, etc. as marked by the carpet tile. I also happen to prefer the aesthetics to the first 3 baffles tested. Next up are a few crossover tweaks where off axis measurements are concerned.

The spaghetti sitting behind the speaker consists of 28 test leads attached to caps, coils and resistors. Very easy to swap out components this way and hear subtle changes quickly. The finished crossover boards are currently being worked on as well.


;

 
« Last Edit: 28 Dec 2012, 08:50 pm by matevana »

sjhomey

  • Jr. Member
  • Posts: 39
Re: New Build: Hestia-SL
« Reply #30 on: 29 Dec 2012, 03:39 am »
The final baffle has a pleasing shape to my eye.

That would be 5/4" spruce in dimensional terms? It looks to be 13" or more at the widest? Where did you find that? What kind of spruce and please don't tell me Sitka. Is the top baffle fairly vibration free?

I'll let you finish before I ask the question and I don't mean how much did it all cost.

You must be pleased. Looks like another well integrated design.

Peter




Redefy Audio

  • Industry Participant
  • Posts: 116
Re: New Build: Hestia-SL
« Reply #31 on: 29 Dec 2012, 05:19 am »
beautiful!

will you do some measurements?

matevana

Re: New Build: Hestia-SL
« Reply #32 on: 29 Dec 2012, 01:25 pm »
The final baffle has a pleasing shape to my eye.

That would be 5/4" spruce in dimensional terms? It looks to be 13" or more at the widest? Where did you find that? What kind of spruce and please don't tell me Sitka. Is the top baffle fairly vibration free?

I'll let you finish before I ask the question and I don't mean how much did it all cost.

You must be pleased. Looks like another well integrated design.

Peter

Hey Peter,

Sitka??? Never! :lol:  They are actually stain grade table tops sold at Lowes and come with nice roundovers on the edges. The baffles use the 24" round while the side panels are 15" round. They are 5/4" thickness and measure very close to 1" with a ruler.  You are exactly right; 13" at the widest point, 7.5" at the bottom and 4" at the top. A total of 4 cuts with a circular saw and guide.

I use Google Sketch-up to lay out the baffle and drivers, then print a pattern in 1:1 size to be used as a template. Works very well with irregular shapes. Note that the top and bottom of the baffle maintain their original round profile, which adds a nice touch. The mid driver's  cutout is chamfered in the back.

Vibrations are minimized by two factors. First, I'm using sorbothane material to "sandwich" the baffle to the mount and the fasteners (screws) sit in over sized holes so they don't directly contact the mount. Second is the fact that the drivers are spaced closely together and all the extraneous baffle material has been eliminated. Less material (of the same design) can translate to fewer resonance concerns.

I think you were also asking about the project cost. Well... not too shabby for the big sister of the Hestia. In keeping with the design mantra, I was able to build the SL's at a cost of under $200 per side for the all active version, including building materials. The passive version (the design I am working on now) will add another $50 or so for component costs, but will allow you to drive the top three drivers with something as small and inexpensive as a T-amp.

They measure out at around 90.5 dB efficiency with a system impedance of 7.8 ohms. They sound great with an SET amp as well. I am using two Yung plate amps on the SL version so the H-frames can be driven in stereo. This is not absolutely necessary but is recommended since a higher degree of imaging is sought. One could easily start with a single amp in mono and later upgrade as desired. 

Baffle material & template:





 


matevana

Re: New Build: Hestia-SL
« Reply #33 on: 29 Dec 2012, 01:51 pm »
beautiful!

will you do some measurements?

Unfortunately my in-room measurement capabilities are limited to a digital SPL meter and 31 bands of test tones recorded at the same amplitude. At this time no single reading deviates by more than +/- 4 dB from a range of 50 Hz through 15k on axis. In tweaking the crossover design, I hope to improve upon that slightly.

That being said, let me rant a bit about one thing with all due respect to others. :green: I have heard speakers that are ruler flat that I would also describe as un-involving. As a musician I am perhaps more sensitive to the weight and timbre of various instruments than many. What drew me to OB initially is their ability to involve the listener, as cliche as that might sound. Pianos should not just sound good, but they should sound like pianos. If you close your eyes, you should be able to picture an 8' deep grand piano in the listening space, as opposed to a pleasant sounding recording of the same. A well executed OB design will do this. I guess my point is that much emphasis is placed on measurement which is certainly quantifiable. Perhaps as important is a speakers ability to draw you in. I'm sure many of the full-range driver enthusiasts will agree. While many of the psycho-acoustic properties are less quantifiable, and therefore harder to measure, there is also something to be said for designing for interpretation as a goal. 


 

guest60106

  • Guest
Re: New Build: Hestia-SL
« Reply #34 on: 29 Dec 2012, 06:43 pm »


That being said, let me rant a bit about one thing with all due respect to others. :green: I have heard speakers that are ruler flat that I would also describe as un-involving. As a musician I am perhaps more sensitive to the weight and timbre of various instruments than many. What drew me to OB initially is their ability to involve the listener, as cliche as that might sound. Pianos should not just sound good, but they should sound like pianos. If you close your eyes, you should be able to picture an 8' deep grand piano in the listening space, as opposed to a pleasant sounding recording of the same. A well executed OB design will do this. I guess my point is that much emphasis is placed on measurement which is certainly quantifiable. Perhaps as important is a speakers ability to draw you in. I'm sure many of the full-range driver enthusiasts will agree. While many of the psycho-acoustic properties are less quantifiable, and therefore harder to measure, there is also something to be said for designing for interpretation as a goal.

I must say that I agree with this. I am a fairly experienced DIY loudspeaker builder but at the same time I have little experience in the measurement and frequency analysis department. For this very reason I have decided to up my game. My wife was kind enough to give me SoundEasy for Christmas. I am now in the process of setting up a small lab in my shop as well as a measurement bay in my back yard. I am going to learn to measure drivers as well as assembled speaker designs and analyze the response characteristics. I have been a mechanical design engineer for 30 some years and I am looking forward to finding out new and surprising developments through my own research. My tastes rarely parallel convention when it comes to design work whether it be loudspeakers or anything else I have designed.   

matevana

Re: New Build: Hestia-SL
« Reply #35 on: 29 Dec 2012, 09:30 pm »
I must say that I agree with this. I am a fairly experienced DIY loudspeaker builder but at the same time I have little experience in the measurement and frequency analysis department. For this very reason I have decided to up my game. My wife was kind enough to give me SoundEasy for Christmas. I am now in the process of setting up a small lab in my shop as well as a measurement bay in my back yard. I am going to learn to measure drivers as well as assembled speaker designs and analyze the response characteristics. I have been a mechanical design engineer for 30 some years and I am looking forward to finding out new and surprising developments through my own research. My tastes rarely parallel convention when it comes to design work whether it be loudspeakers or anything else I have designed.

Another member was nice enough to share similar comments via PM this afternoon. I wanted to echo a paragraph he wrote that I thought really nailed this sentiment (and stated more eloquently than I ever could):

"Couldn't agree more with your comments about measurements vs. involvement.  I'm using a Lowther in a "no baffle" stand coupled to a transmission line bass.  I'm positive it measures poorly and yet, everyone that has heard it scratches their head and says "there is no way that should sound so good".   OB just loads a room in a more natural way to my band director/ trumpet player's ears. One advantage my weird system has is using active crossovers. Being able to adjust response around middle C lets me dial in cello and basses so they have enough body.  I think you are saying the same thing about your designs having realistic body and involvement".


Again, I don't suggest disregarding measurements entirely; I think they can be very helpful in establishing a baseline, determining a driver's actual vs published T-S params, etc..  But I do think there is something to be said for fine tuning by ear once that standard is roughly attained. It's also helpful if that ear has the experience and ability to discern how instruments should sound, and help establish that emotional connection one gets when everything sounds just right, as subjective as that might be.




 

pandpliers

  • Jr. Member
  • Posts: 12
Re: New Build: Hestia-SL
« Reply #36 on: 29 Dec 2012, 11:03 pm »
Hi I have been following this hestia sl build as well as some of your older ones.  What Yung amps are you using?  I am thinking of getting a pair before they go  off sale at PE.  I was thinking of a pair of the yung 300 or 200 but do you recommend the ones with 6db boost or not?  I am leaning more toward a pair of the 200 with boost but want to know more from you before I order. Also are there any other options for the lower woofer?  Thanks KEEP UP THE GOOD WORK!   The table upper baffle looks AWESOME!  I want a pair in my living room.  :wink:

matevana

Re: New Build: Hestia-SL
« Reply #37 on: 30 Dec 2012, 04:07 am »
Hi I have been following this hestia sl build as well as some of your older ones.  What Yung amps are you using?  I am thinking of getting a pair before they go  off sale at PE.  I was thinking of a pair of the yung 300 or 200 but do you recommend the ones with 6db boost or not?  I am leaning more toward a pair of the 200 with boost but want to know more from you before I order. Also are there any other options for the lower woofer?  Thanks KEEP UP THE GOOD WORK!   The table upper baffle looks AWESOME!  I want a pair in my living room.  :wink:

Hi and thanks for the feedback. I am using two of the 300 watt amps w/o boost. In my current setup, each amp drives one Usher 8955 bass driver @ 8 ohms, so realistically they put out around 175 watts. The amps are known to put out a true 300 watts when driving a 4 ohm load.  Keep in mind these are class D amps so the distortion level is notably lower at 8 ohms then it is at 4.  The damping factor appears to be higher at 8 ohms as well, which will likely benefit bass drivers with higher than average total Q (Qts), as is often the case with OB woofers. 

I avoided the boost version thinking that 6 dB at 30 Hz will do little more than cause an 8" driver to go into over excursion. You will likely hit the drivers xmax at lower volume levels than the same amp would without boost. And since you cant defeat the boost feature easily, it's better to be safe than sorry. I can tell you that the quality and quantity of bass in the SL design is impressive. 

I really like any of the 8" Usher drivers. I have the Usher 8137a in OB in my bedroom system and they are excellent as well.  The 8" Ushers are quite resilient, fast and sound great IMO. Most important, the motors are extremely quiet. Try isolating other (sub)woofers in OB and you will often hear motor noise from the rear of the driver. To me this is very distracting and the Ushers don't seem to have this problem. Remember that most speaker manufacturers allow a certain amount of motor noise in their designs knowing that a well damped cabinet will absorb the bulk of it. This is not the case in OB.

I have also been impressed with some of the 8" designs from Aurum Cantus, SB Acoustics and Vifa. I am not sold on the Peerless 8" SLS woofer unless you consider multiples, and that may go for some of the Seas 8" drivers as well. I have not had good luck with Tang Band
in OB.

matevana

Re: New Build: Hestia-SL
« Reply #38 on: 30 Dec 2012, 05:33 pm »
Here's a picture of the working crossover. I'm going to live with this for a bit before posting final component vales.




Rudolf

Re: New Build: Hestia-SL
« Reply #39 on: 30 Dec 2012, 07:43 pm »
Matevana,
I wonder how you would think about taking the new baffle theme one step further - by replacing the circular side baffles with the new edgy shape:



The side wings would start at the widest point of the speaker baffle and narrow towards the bottom. This would give the whole thing an even lighter appearence.

Rudolf