| slhijb |
Been designing a new speaker project for several months now and ready to take the next step, purchasing the remaining drivers. Since driver selection is so critical to success of the final design and these are rather pricey drivers, I’m looking for comments or lessons learned from anyone that has experience or knowledge of this type driver combination (or fractions thereof).
Tweets: Dynaudio Esotar T330D (already have these)
Mids: C-Quenze 15H (5”) w/Kapton
Woofers: 2each (4 total) Scan Speak 21W/8555-01 (allows for smaller box and increased sensitivity for baffle step compensation)
Two box general Watt Puppy style design, using BassBox Pro and Xover Pro for design calculations. Box design is pretty well complete (closed boxes) and Xovers still being worked on. Large room 25’ X 25’, but limited space for speakers. For WAF reasons, they have to be reasonably sized boxes.
These drivers appear a good sonic, crossover and timber match, but am I missing anything before I take the final plunge?
Thanks, slhijb |
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| slhijb |
| No help or comments.... anyone? |
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| Curmudgeon |
Hookaayy, a cautious reply. (Albeit a lot more lengthy than I'd planned.) I think you have chosen well. You don't want to pad either the mid or woofers to adjust sensitivity, so some care there is needed.
A friend and I are building two pair that are similar.
The Great Project uses one each of the Skaaning C-Quenze 15H, SS Revelator 99000 tweeter, and SS 25W 8565-01. The 15H is the standard unit with concave dust cap, no kapton. I have heard that there is now a version??? with a new surround.
The pro's: timbral continuity is seamless. Dynamic range and transients are in the breathtaking class. Transparency is easily the equal of anything I've ever heard. (I've not heard any of the big 'stats lately though.) I cannot really say that it has a sound of its own; use slightly warm interconnects, and it is a slightly warm system; use slightly analytic interconnects and you have a slightly analytic system. The best recordings are magnificent, and it does not make poor ones sound worse.
The cons: the flip side of the above. You have a tiger by the tail. It happily responds to the very best amplification and crossover components; the clarity is such that there is no doubt whatsoever. Components that I was perfectly happy with in the past are suddenly shown to be less than the best.
We have mounted the mid and tweet in a box which is covered with a rounded semi-teardrop felt covered foam mountain, to reduce diffraction. The woofer is in a 6 cubic foot enclosure, 1" felt lined, tuned to about 17 Hz. (Extended Bass Shelf.) No audible woofer hangover. ("Fast", to the degree that that applies to woofers.) Cabinet has slanted back, shelf brace. Mid subbox is sealed.
We tried to watch xo component cost; only moderately successfully. Tweeter xo uses silver home-wound coils, polystyrene/tin capacitors.
Mid uses a silver foil lowpass (Just discontinued by Alpha-Goerz due to Ag price volatility) and 10 Northcreek 225V metall'd polypro's, 5 each anti-parallel. These may be becoming unavailable as well, VERY good value anti-paralleled. Other values tin/polypro.
The woofer uses an Erse low DCR inductor, metall'd polypro's. House curve LR, for about a -3 dB shelf high mid and tweet.
Mills 12W resistors throughout, Cardas lugs and their patent lower cost "binding posts" . XO moved back to the amp, wired with Cardas bare silver wire; home made speaker cables, Cardas 9.5 ga hookup for the woofers, 5 X Cardas 15.5? "ribbon -+-+-" and 5X Cardas 21Ga silver for the tweeter. XO star ground wired.
Home made interconnects still evolving; currently a variant of the Van den Hul hyperflex design seems to be becoming the design of choice, with Cardas silver and RCA's.
Rest of the system for evaluating all this is Levinson 30 DAC, Audio Synthesis passive pre, (modded slightly) and either a Bryston 4B or Pass X250. We just finished rebuilding the first XO to match the improvements in our second; imaging seems fine (not a major issue for either of us) and room placement seems relatively unfussy so far.
Other random thoughts. We had to put a trap on the woofer to suppress the HF breakup. (At least -50 is suggested.) The xo is basically first order multi-slopes, an idea cheerfully "borrowed" from the Thiele speakers. MLSSA and LEAP were used. (Do you have any measurement capability? We really needed it. ) |
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| slhijb |
Curmudgeon, great reply! Thanks for sharing your project. Sounds absolutely stunning. It’s encouraging to hear your system’s going so well. Please keep us all posted on your progress, I for one am totally interested.
As a long time audiophile, but newbee speaker builder, I’m perplexed with 3-way Xovers. After 4 books, emails to DIY experts, reviewing web sites / diy forums, and working Xover Pro software, I think my head’s gonna explode. The 3-way’s very tough to get right. The first order multi-slope approach sounds interesting. Any insight or recommendations will be much appreciated. Would love to go 1st order if practical, little or no padding on the tweeter with cross @ about 2200 (Esotars can handle a large HF areas very effectively) . Woofers aiming at around 190 - 240 Hz. Shooting for a large gaps between Xovers and keeping them out of key vocal areas as much as possible.
Also, not clear on placing a trap on the woofer to suppress HF breakup? Help.
In response to your comments. I narrowed mid driver selection to the Skaaning C-Quenze 15H, 18H, or the Audio Technology 5” Flex unit. To help break the deadlock I emailed Per Skaaning and described my project. He responded that the 15H will be the best fit with its “new cone” (had kinda expected him to recommend the Flex unit). David Gatti said he got the same response when designing “the Delta“. Exactly what the “new cone” changes are, I don’t know. Sounds to me like you may have the newer cone. Maybe someone can chime in.
You discussed that your new system as very revealing, and that quality amplification and crossover components are a must. I currently have Merlin VSM Millennium speakers. They use the Esotar tweeter & SS 18W 8545mid woofer - superb speakers. Will use these to A/B compare the diy speakers once at testing phase. My Core system is: Amp - McIntosh MC-352 SS (300W/ch), PreAmp - McIntosh C-2200 tube, Cardas Golden (earlier version of the Golden Reference) and Cardas Neutrals interconnects. LAT international SS-1000D speaker cables, Electrocompaniet DAC and sundry other components.
Xover components planned: Caps - Either AudioCap Theta PPTor Hovland Musicap, Inductors - Alpha-Core and Goertz, and resistors - Axon/Mills. Will also look hard at silver wiring and solder since the McIntosh & Esotar tend to be on the warmer side.
Test equipment: Eyeballing: -- Wallin Jig, Behringer ecm8000 mic, and ub802 preamp, have the M-Audio soundcard and possibly Speaker Workshop software.
Plan to continue Xover design through further research and Xover Pro. Expect to have Madisound also design Xovers VS my designs using their chamber measurements and LEAP. Once speaker boxes are assembled, will build prototype Xovers using cheap materials and tweak the system. Once it’s right, will build final Xovers. Xovers will be in separate boxes outside the speaker cabinets for future adjustments. At least that’s the plan today. May change as I go.
Jim
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| Curmudgeon |
I'll try to expand a little on some of the questions. We found out (usually the hard way) that a great deal of time and patience, and excellence at all stages is required.
Some of our learning process. (I had designed and sold commercial speakers, so I was surprised at how large the next step of quality was.)
Do not EVER, for any reason whatsoever, at any time, in no way, use clip leads for breadboarding xo versions or changes. We use Wonder and Cardas solder (the older lead containing) now.
Forty hours is a good rule of thumb for breaking in components before listening evaluations, although more for drivers is a good idea. (Inductors don't seem critical, caps certainly do.)
You will need your measurement and design tools.
Multi-slope crossovers. First order crossovers place a great burden on the drivers. Very few drivers are suitable. The problem is that the drivers need to be able to handle out of band material well. Peak to average ratio for classical music, uncompressed, is easily 20 dB. At 6dB per octave, that's 3 octaves; so you can have out of band peaks 3 octaves out equal in level to the average inband level. Not a reasonable thing to ask of drivers.
Thiele loudspeakers have used the multislope principle for years, and I happily "borrowed" from them. I spoke with Jim (?) Thiele at a CES once, and he told me that a second pole about an octave away from the crossover point, and a third another octave away, helped with the out of band power issues, without too great a phase error at crossover. I'd used the same approach. I've not seen a good how-to multi-slope design article for the amateur. As ever, these are the final acoustic slopes, resulting from the crossover and driver rolloffs summed, so the specific design will depend heavily on the driver out of band response. That's a big reason as to why your measurement equipment will be invaluable.
I like the Vance Dickason "Loudspeaker Design Cookbook". The title is misleading, it is far more than a cookbook. Traps are covered well there. We found that our choice of woofer (like many stiff-coned drivers) breaks up well out of band, (the 2500 Hz region) but that the distortion products (non-signal related on the whole) are very audible, and must be strongly suppressed. For comparison purposes, that area is now about 60 dB down. Because the mid is so transparent, it will not mask the woofer's misbehaviour at all.
I'm acquainted with the 8545 driver; it is very good indeed, but the Skaaning is a whole 'nother thing. The C-Quenze units are the newer frame design. We bought our drivers 3(?) years ago, so they must be the older surround/cone design. I have also heard rumors of silver voice coils....
Silver wire. To our ears, silver is the warmer and the cleaner of the two. I know many feel otherwise, but silver (for us) was always hash free in the upper mid, and all the copper we tried was not.
I don't think Madisound carries the 15H, so you probably cannot use their LEAP service. And I do think the 15H is the unit you want. Very good idea though if it is possible.
Diffraction effects were very audible to us, and we went to a lot of effort to avoid them.
Sadly, I cannot endorse the idea of using inexpensive components to breadboard your crossover. As you know, with systems of this level, you are spending a lot of effort to NOT hear things. Colleague and I are both unusually sensitive to upper mid hash and grain, and that is one of the things you pay (quite a bit) to not hear. We spent a lot of time and money, learning and relearning that we just could not reliably learn anything using inexpensive components. I cannot speak to your capacitor selection as we have not tried those. We used North Creek as the basic capacitors (woofer, some conjugates and Zobels) because they sounded fine to us and they were on sale that summer. From what I have read of the Theta's, they should do well. Mid and tweet as I indicated above require as good a capacitor as you can stand to pay for. We did not try Axon resistors; we found the MIlls to be fine, and did not look further. And because your system is different, (and room, and music sources, and ears, and cables, and, and, and) your component choices may well differ from ours. For example, I suspect that your cables are "better" than anything we have.
And to reiterate, capacitors, capacitors, capacitors. We cannot afford the exotics, copper or silver foil, teflon dielectric, but do use the tin foil polyprop and tin foil polystyrene (sparingly!) And we follow Serengetiplains' adventures with great interest.
Oh, and the crossovers are built on the white polyethylene 1/4" pegboard from McMaster. Spiffy.
PS With regards to the wire and other issues, both of us, design engineers, started out as skeptical indeed about some of the things we found out. However, our ears ruled, and we'll let the theorists and the material physicists sort out why we hear what we do someday. |
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| v-bro |
You people seem of the like I can learn from, true "audiophiles".
If I may ask, isn't making "the box with everything in it" (drivers, filters etc.) merely a consideration of ease?
I have very good though not very extended experiences with multi-amping and filtering them on the inputs. I filtered them with an active filter in the past (very expensive device from marchand) but wanted to make a less complex "routeing" and decided to make a passive line level filter (pllxo). Marchand also sells a complete filter like this, wish I had the schematic and component list.
Isn't haveing no components between the amp and the speaker an advantage to the amp being able to have better "control" on the driver and profit better from it's dampening factor?
Or are there any disadvantages on pllxo-ing besides insertion loss and an impedance shift on the amp's input?
How can the split outputsignal from the source be "decoupled" towards each filter? And how can that be done? Or do I really have to calculate every value taking in account the values from the paralleled filter for the other driver? This would mean that I can't make it a 3-way system in the future without changing all the filters again:bawling:
My asking this is because I like to learn instead of buying some ready-made one...(and don't have much money these days:()
And I have noticed a difference in sound when parallelleing the filters. |
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| Curmudgeon |
I can't help much on the pllxo issue, as I do not have experience.
I thought I'd mention a couple more stray items that have occurred to me that might be helpful.
The mid box also has a slanted back, and is fully lined with ~ 1/2 felt. Also, the small flat rim of the magnet is felted to cut down reflection. For the mid, the mounting cutout is beveled at a 45 degree angle, leaving 6 (?) small islands for the mounting t-nuts. And the bevel is, surprise, felted. |
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| slhijb |
V-bro, sorry but I must also plead ignorance here. Just don’t have experience with these concepts. I’m considering bi-amping, but just in the early research stages myself.
Crumudgeon. Thanks for another great response. I took a little time to absorb your comments. Have come to the conclusion that the first order multi-slope Thiele / Crumudgeon crossover design is a bit advanced for me, especially without a good how-to or multi-slope design article to draw from. I’ll probably go down several Xover roads before a final selection is made, but for now am researching the following:
Concept #1. Bi-amp the 3-way speakers using both passive and active networks. Use a 2-way active low level crossover in front of the amp to filter the mid & high frequencies, from the low frequencies. The active filtered low frequencies will be sent directly to the woofer (driven by one amplifier). The mids and highs are actively filtered before the second amp and then directed to the passive 2-way crossover.
Note. At this point tri-amping is not an option. Not sufficient room in the audio component rack or sufficient green in the wallet for a 3rd amp with all the trimmings.
Concept #2. Tony Gee’s Andromeda 3-way crossover. Essentially designed as a 2-way system with a sub-woofer. He uses a 2nd order series filter for the tweeter & mid, and a parallel 1st order filter for the woofer. Schematics are attached and below.
http://www.speakerbuilding.com/cont...16_scematic.jpg
I emailed Madisound, but haven’t heard back from them. Have spoken to them before and they have always been super accommodating. Hopefully, they will support.
Just starting to research more closely Xover component quality issues. Hadn’t really looked at the prices of some of the high quality capacitors and such… ouch! However, until the Xover design is complete won’t know what the $ damage is, but your advice will certainly serve as a template. Xover component quality will be very high, commensurate with that of the drivers and cabinet design. For the tweet & mid crossovers I‘m considering Mundford Supreme Silver/Oil Caps and at low-pass filters as mentioned earlier. Again, will depend on the Xover results.
Your point is well taken on not building prototype Xovers with cheaper components to final tweak the design, then going final with high quality components. I’m sure you’re right that the subtle (and possibly not so subtle) nuances will be missing and the ultimate design will suffer. Wow, hope the initial LEAP design’s pretty accurate or things could get expensive.
Agree with silver wiring. The way to go for this project.
Had not thought of using felt for the magnets and beveled / chamfered backs, but I’m getting a roll of felt anyway and will definitely attach it at these locations.
Thanks again, any ideas on the two Xover concepts? |
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| Curmudgeon |
From a theoretical standpoint, active crossovers have a lot of advantages. Very attractive.
The problem I have with active crossovers is the difficulty in implementing the active stages; it is not easy or inexpensive to make a preamp equal in quality to the amps we've been discussing. And an active crossover can have quite a few stages. Coupled with the cost of an additional amp at this level of performance....
If I were to undertake an active, I'd keep it as simple as possible. A passive RC high pass, and the output of an opamp (integrated or discrete) taking the difference between the passive's input and output will sum to the exact input waveform. The opamp's output will only be first order however. (Been quite a while since I messed around with that. ) There is nothing to prevent you from using a blend of both methods.
We felt that excellent results have been achieved by others using very conventional methods, and, rather than reinvent the wheel, or try for a stunning breakthrough, we'd simply try to use classic methods implemented very carefully. And that alone was enough project for us! A bit more than we expected; the driver transparency makes hitherto inaudible differences perfectly plain.
One approach to multislope is to use modern optimizing design tools. I can only speak of LEAP, but I know other tools have worked the same way, as I used one (XOPT?) pre-LEAP. Basically, you construct a guide curve, for each driver, with the desired response. Then you give the program the driver response, the guide curve, and a reasonable circuit. (That is, you don't ask for a fourth order response and feed it a second order circuit. And the originating values should bein the ballpark as well.) The tool will show the initial response, and you can tweak values as needed to get somewhere close to the guide curve; then activate the optimizer. It will change the values as required for the final response to match the guide curve as closely as it can. When satisfied, you repeat the process with all stages for the final result. With some, depending on the effectiveness of the convergence algorithms, you'll get different results by modifying the initial values slightly. (LEAP's convergence algorithms are excellent incidentally.)
It takes some practice, and understanding of what you want, to use one of these tools effectively. This is really the most practical way to develop the base design. This sounds simpler than it is in practice, as you will listen, measure, modify, recalculate, and relisten as needed.
LEAP may be overpriced and overkill for your needs; but it is extremely well designed software and very good value in its league. There has been a lot of discussion about other design tools more in line with amateur budgets.
The Mundorfs, from what I've read, do seem very well worth trying. And yes, experimenting with components can get expensive.
A lot of effort should be spent on the basics; diffraction, internal reflection, (reflections off the rear wall, and back through the mid cone, delayed, are EVIL) physical alignment of the acoustic centers, star wiring, connectors, and whatever I've forgotten are all important. If I had infinite resources, I'd experiment with the stacked layer cabinet techniques. And more cap types.
You should, of course, be well acquainted with live music, and measurement equipment that allows you to take waterfall measurements is a big help. And again, I do recommend Vance Dickason's book highly. |
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| hermanv |
Hi, I am the other half of the team that made the 3 way speakers that Curmudgeon describes. I want to support all of his statements and expand a couple slightly
We discussed passive vs active crossover design, we may be wrong but three first class amplifiers to drive a beast like this seemed more costly than passive crossover parts (actual costs are closer than you might think). We spent a great deal of money, a lot of it by being forced to upgrade other system parts and wires which suddenly were revealed as lacking. Not that the old system was of poor quality, it was all name brand seperates.
I wanted to stress that if you are going to use first class drivers and wish to enjoy their fullest capabilities very carefull attention to detail is required.
Use only first class crossover parts especially in the mid/tweet. Connectors, wire, grounding, lead dress, materials besides the caps and inductors matter a lot.
Internal cabinet reflections, diffraction effects, correct accoustic centers are most important. Our design has the tweeter at just above seated ear level (43 inches I think) the mid is 6" lower leaving a fair amount of room between the mid and the floor. Much to my surprise woofer distance from the floor mattered quite a lot, so did port placement. The longest distance didn't begin to approach 1/4 wavelength of the crossover frequency. I'm quite sure there is no one correct dimesion, but the sound of your design will change with the woofer distance from the floor.
Curmudgeon didn't mention it, but the design, construction and listening tests required a surprising number of man hours (time flies when your having fun, is this a great hobby or what?) I suggest a partner, there is a lot of detail and two minds are better than one, besides there are days when the results just don't match your expectations and you need that shove to tackle it again. |
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| slhijb |
Boy what I’d give to live close to you guys. Thanks again, all great stuff! Hermanv, don’t know if I can find a partner for this project, most of my friends are still wondering why I don’t just buy a Bose Acoustic Wave Machine and be done with it.
From the beginning, this project’s been broken into 4 phases.
1. Driver selection.
2. Cabinet design & construction.
3. Xover design & construction.
4 Final testing & tweaks.
Final driver selection took months with several large spread sheets, hundreds of drivers considered and many hours plugging different driver combinations into my cabinet and Xover software. Think it’s pretty good now, but still a little squishy on the woofer selection. Using closed boxes so trying to balance overall box size (limited available space for the speakers) with F3. Agree that the woofer placement in relation to the floor will be critical. My original lower woofer box design had a tilted slope of about 5 degrees. I’ve kept the measured time aligned slope for the upper mid - tweet box, but went to a straight on axis woofer design for the lower box. The bottom woofer will be placed as close to the floor as practical.
Cabinet design is also about complete. The design considerations like transient response, phase alignment, standing waves, baffle step compensation and cabinet vibration & resonance to name a few have been worked and I’ve really had a ball doing it. In fact, our designs sound pretty similar. Driver selection and tweeters & mids height about the same. Have over 40 typed pages of notes, using as some of these references:
Speaker Building 201, Alden
Designing, Building, and Testing Your Own Speaker System, Weems
Introduction to Loudspeaker Design, Murphy
North Creek Cabinet Handbook & Wiring Guides, George Short III
BassBox & Xover Pro Design Manuals, Harristech
And Yes, The Loudspeaker Design Cookbook, Dickason
Am now immersed in the dark world of Xover design and am weighing all the options. Remember, I don’t have the knowledge or experience either of you have (in fact, nowhere close), so a hi-end adjustable active Xover bi-amped is worthy of consideration. Feedback from George at North Creek, Tom @ Madisound and most the above books have all recommended I take this route, like Vance Dickason‘s where he recommends on page 131, ‘Because of the compromises and tradeoffs of passive 3-way designs, you should seriously consider using an active network for the second frequency division point.’
The current plan is the 3.5-Way speakers will be bi-amped using an active digital 2-Way crossover component between the pre-amplifier and (2) amplifiers. The bi-amped signal will be divided with one amplifier (tubes) supporting the tweeters & midranges and the other amplifier (SS) supporting the woofers - a classic concept I know, but one that has always intrigued me. The simpler passive 2-way crossover will be used to divide the final signal to the midranges & tweeters.
- The active adjustable digital crossover will be something like a Marchland tube or Threshold PCX system.
- I’ll check the quality of components like caps & inductors and if upgrade is needed will do so.
- A Line Level Volume Control device will be used for volume level / gain matching between amplifiers. Looking at putting this control device on the woofer SS amp.
- The passive 2-Ways crossovers will be LEAP designed by Madisound (spoke with them yesterday). I’ll modify and tweak as needed.
This concept, with the adjustable active Xover to a passive 2-way (plan low slope simple with minimal Xover components), will greatly simplify many of the more advanced aspects of Xover design and application. Once all the pros & cons (like cost) are measured, whether or not this is a practical application for this project will become apparent.
As for final testing and tweaks, just started to crack open that door and peak inside. Lovely, my wife will be thrilled with the in-room testing phase.
In the end, there are only a few guiding principles; keep it simple, don’t let cost be the primary determining factor (but definitely not a cost-no-object thing), go with very high quality components throughout, don’t rush it, have fun through challenge and leaning… Oh yes, and build a great sounding audio system.
Once I get the written designs in a little more coherent format would love to email you a copy to see what ya think. This may be a little while however, still haven‘t finalized all the plans.
Jim |
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| tf1216 |
hermanv and Curmudgeon,
Would one of you please describe how you dampened the inner walls of your cabinet, as well as, chose the proper port placement.
I have a custom C-Quenze 18H driver with an underhung motor, sd system, and a special concave cone that I want to use with a Aurum Cantus G2si. I only have a 0.5 cu. ft. enclosure to work with so I must port the cabinet. Any information would be great. FYI, I have an active XO to use with a bass unit so the 2-way does not need to extend too low.
slhijb, I am sorry to steal your thread. I love what you are trying to do. |
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| Curmudgeon |
We did not want to spend an eternity carefully comparing all options for a given function. We lined the woofer cabinet interior with 1" wool felt, using a water based contact cement. Incidentally, we sealed the cabinet with a water based polyurethane varnish first, just because MDF absorbs water. A thinner thickness of felt might have worked, but we did not compare. Pretty expensive approach, but seemed to work well for us. McMaster was the felt source. F-11 and F-13 grades were used; we never really settled, but tended to use the softer F-13 for mid and highs applications. I think F-13 has been superseded now.
We were quite suprised that woofer height made a difference; one possible explanation is that due to the slow rolloff, we were seeing the upper bass floor bounce suckout effect. The woofer wound up about 18" above the floor, with the vent below it, about 8" up. We're using the modern keen stuff low turbulence vents.
Both HermanV and I like neutrality, transparency, timbral accuracy, and above all perhaps, the absence of upper midrange hash or grunge. It's the latter that has had the most to do with the investigations into components and cables; the transparency, dynamics, etc. from those investigations came as welcome complements. |
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| hermanv |
Although acoustic stuffing can add some virtual volume to an enclosure it didn't seem to offer very much in the way of damping internal sonic reflections.
Driver cones are acoustically transparent (I guess they have to be) so besides sloping the back wall, we used the thick felt in the woofer enclosure. Curmudgeon didn't mention that we used 1/2" felt inside the seperate mid enclosure which also had a sloped back wall. Getting rid of internal reflections is pretty valuable, it's surprising how many relatively expensive commercial speakers don't appear to bother.
When we were done lining the cabinet, shouting into the empty driver opening did not produce either an echo effect or any particular sonic peak. The wool isn't cheap but it does deaden sound very well.
We used 3/4" MDF with a partial baffle face doubler where he woofer mounts and two internal "shelves" pierced with very large holes as wall stiffeners. Many speaker designs go to extraordinary lengths to make the enclosure absolutely ridgid. What we did seems adequate as there is almost no vibration when the outside walls of the enclosure are touched lightly with our fingertips while music is playing.
It was harder than I initially thought and took longer, but the only speakers either of us have heard that sound as good, were just far too expensive for us to consider. |
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| v-bro |
Stiffened enclosures can show higher frequency resonances passed through by the basket of the driver, bitumen can help alot there.
A piece of bitumen in the middle (not too symmetrical) of any larger surface helps a lot to make it "acoustically dead".
Than it can be covered with felt...
I've known "audiophiles" who cover every square millimeter inside the enclosure.
Sticking any dampening material to the inside of the cabinet will only be done in order to dampen cabinet resonances, the material used better be high in mass. Though sticking the felt to the walls will keep it nicely in place, reflections in lower freqs wont be bothered at all. Reflections in mid-to higher freqs will be dampened enough when the felt would just hang loose. Getting rid of reflections in lower freqs can only be achieved properly with a transmissionline enclosure without curves(straight) or rolled up smoothly.
And never cover the baffle-side with reflection dampening material! |
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| luvdunhill |
just curious, did these designs ever materialize? either of you happen to have more detailed plans?
Thanks! |
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| hermanv |
| quote: | Originally posted by luvdunhill
just curious, did these designs ever materialize? either of you happen to have more detailed plans?
Thanks! |
My partner and I did finish the first pair of speakers. We are building a second set (for me). I'm unsure if we want to post plans, I'll discuss it with him next time we get together.
I can say this:
1. Driver selection counts (no surprise) and as in many audiophile products, on the whole, more expensive drivers tend to sound noticeably better.
2. Details count, careful cabinet construction; paying excessive attention to both internal reflections and external diffraction issues are important to realize the best that a good driver can deliver.
3. Crossover parts matter a great deal if your speaker is intended to compete with truly good commercial designs and you wish to bring out the best in your drivers. As an example, we used silver foil coils in the midrange and understand that they are no longer available at any price.
4. We spent far more money and time than we expected, still far less than the cost of what we believe are commercial speakers with a similar sound quality.
5. We also found ourselves caught in a very expensive equipment upgrade spiral. As our speakers improved, flaws in the existing equipment previously tolerable became far less so.
6. Most CDs have far more information content than we suspected and a surprising number of them transitioned from OK to wonderful and from unlistenable to OK after we upgraded the equipment and neared completion of the speaker design.
7. Voicing is tough; any number of combinations can be made to sound very good, trying for a live music absolute results in a speaker that on the whole doesn't measure very flat. We presume that recording engineers on the mixing console often tend to boost both bass and treble to generate more excitement in the recording and that room effects exacerbate this tendency.
All in all we are very pleased with our effort. I can also say that the effort in and of itself was enjoyable. We both have a feeling of accomplishment. |
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