Thanks for all the responses. Sean, I think I will contact Clayton for his expertise and opinions on series crossovers. I will probably also get in touch with Bud Fried. Herman, I will check out Gizmo's ideas. I have considered horns, but have never really fell in love with them. I do have a pair of horn speakers in my living room that my father built in the mid 1960's. They are exactly as you suggested. The sound of them is pretty good. Perhaps, I will give higher quality horns more consideration.
I am not at all interested in a 5 channel HT setup, and expressed these feelings explicitly to my girlfriend. She has no problem with this, and basically just wants to have a nice looking setup in the family room. One where we can watch tv and she can sing karaoke. Whether my woodworking skills are up to the challenge(to make something "attractive") is the question. Her reasons for wanting a good amplifier/speaker arrangement are completely to appease her boyfriend, who happens to be waaaayyy too serious about audio.
As far as the excellent speaker questions that were raised, here are my rapid fire answers(sorry for my lack of clarity in the initial statements)... I was stating that the midranges(or mid/woofers) be run flat out(no caps, coils, or resistors), and wired in series in an overall parallel crossover network. Wiring the entire loudspeaker in series would preclude me from keeping components out of the path of the midrange drivers. Rgreene2, Triangle(glad you mentioned them) is one of the speakers(along with Eggleston and personal experience) which have proven to me the benefits of running the midrange or midwoofer with no crossover components in the circuit. In my parallel crossover approach, the tweeter would have a film and foil capacitor wired on its positive leg, and a resistor(if needed). As far as woofers(in the strict sense of the word) go, I am still undecided. They suck a good deal of current. I may just build these speakers with nothing larger than 6.5" drivers. If I later decided that I really needed to have that last octave, I could go with a pair of subwoofers.
Still have a lot of thinking to do... Things like do I use a REALLY dead cabinet, or more loosely damped(that everything old is new again thing)? I'll decide that after I figure out the crossover, but have always felt a dead cabinet was the way to go. Double thick walls(featuring MDF and plywood), with a layer of something between them(Swedak, viscoelastic, or other polymer), corner braced internally, and BlackHole 5 on the inside walls. |
Thank you Sean! I will think about horns in a more thorough light. The cabinets of my father's speakers(horns with cone woofer), while excellent for their day, can be improved in several ways. Also, the quality of the passive parts(coils, caps, resistors, and wire) have improved quantum levels since those speakers were built. I will also take your advice about the "diffusors" to heart.
You are quite correct about the cost of BlackHole 5. I once made a few "sound boxes" at my previous company. We manufactured EL(electroluminescent lamps), for use in cell phones, pagers, night lights, etc. The whole technology is simply a capacitor that lights up when supplied with AC voltage. There was a lot of noise generated via the AC voltage(coming from the inverter)/lamp. My job was to get rid of it. I looked into anything I could. The sound boxes were just basically speaker cabinets we built(minus the speakers, but with a window to view an inserted SPL meter), which insulated the lamp/meter from the ambient noise of the plant. Got lots of wonderful experience with sound insulation materials. Things like acoustic foil, SoundCoat, foams of every sort, viscoelastics, rubbers, silicones, polymer formulations I developed(applied via screen or pad printing). In the end, the best solution was to simply screen print a third electrode(using my carbon resistor paste) which served as a "shield".
The experience of building those boxes and insulating them(with foams, SoundCoat, foils, BlackHole Pad, BlackHole 5, Swedak, etc.) was invaluable in teaching me about quieting down a box. Materials were free(either sample or out of the company's money), and I was being paid. BlackHole 5 proved to be an excellent product(I like the viscoelastic/multiple foams combination), and we did end up buying a bunch.
To be honest, I can(and probably should) build that BlackHole 5(or better) using viscoelastic sound panels(probably the same as the sheets you are getting from PartsExpress), and two kinds of foam(from Foamex or whoever) for a fraction of what Orca's retailers charge for it. Even incorporate some acoustical foil(very effective stuff) in the my homebrewed insulation.
Now I get to use all of that information! Speakerbuilding is an immense subject, and no one has all the angles covered, but it sure is fun to play this game. If you are going to be undertaking a similar project in the future, it would be great to bounce a lot of ideas off each other. Again, thanks for your help. |
Sean by the way, I just came across a thread on Tweaker's Asylum from 'Clayton Oxendine' regarding a series crossover question(via web search on "series crossover"). So, I now have found at least one person in the world who has knowledge of this mostly forgotten technology. Again, thanks for your help in steering me toward this person! |
Noquarter, thanks for your input. Last night I visited a great website(sorry that I don't remember it now) that dealt with series crossovers in a very strong manner. Featured prominently were John Risch, Clayton Oxendine, Bud Fried, and others. Lots of good information. Including things like zeta(the important thing in series crossovers) calculators, and some real world projects. I am sure that some of the information I will relay here will be incorrect; it was a tremendous amount of stuff to drink in in a very short time.
Zeta is one of the determinants in how quickly the crossover rolls off the driver(???, I kind of forget now). It seems that a zeta should range between 0.7 and 1.2+. At 1.0, it is more analogous to a parallel network. A zeta of 0.7 is said to make the speaker much more upfront in sound(a good rocker's speaker), while 1.2 is more laid back(more like an audiophile speaker - "Boston Bland?").
A two way, 1st order series crossover is very simple to build. In fact, it uses the same values for the cap and coil as the 1st order parallel network. Obviously, how they are connected is different. I do wonder what a series crossover in my speaker buys me. Running the mids flat out would obviously save me the cost of the coils. I am not sure if the sound would be improved over running it with nothing in the circuit. I am also not sure the sound would be detrimentally affected by the wiring of a cap on the positive leg of the tweeter's circuit(ala a parallel topology), as compared to the way driver's are connected in the series crossover configuration.
Wiring in multiple midrange drivers is something that the author has described(in several examples), so he has that question of mine covered. One of their rules is to use drivers that feature a very broad operating range. I did a little thinking of the midrange, and my desire is for one that is very efficient. The Focal Audiom 7K comes to mind. About 97 dB sensitive, with an 8 ohm impedence. I remember it being pretty flat from 100 to 10000 Hz. Drawbacks are the lack of bass response, and extremely high cost of this driver. I believe they also manufacture a driver that gives up 1 dB of sensitivity at about a 40% cost savings. I really like Focal mids and woofers; finding them punchy, dynamic, and clean.
Another critical factor in the series crossover are the coils. It is important to get as low a DCR as you can afford. AlphaCore Goertz were recommended over Solen and North Creek. If I remember correctly, the rate of rolloff is also related to the DCR.
I will look into the Infinity tweeters at the website you listed. My concern with them is their sensitivity. Do you know that offhand? I presume it would be much lower than that of the Raven. Not that I have decided to use the Raven, but it is on my short list. |
Lots of good dialogue here Noquarter. Thank you. If you are interested in seeing an interesting site on this series crossover "thing", please go to
http://home.iprimus.com.au/gradds/index.htm
It may just keep you busy for a while.
You are correct in what you say about the North Creek coils. It is just obvious that their 8 or 10 gauge coils would have a lower DCR than AlphaCore Goertz, whose largest are 12 gauge for copper, 14 gauge for silver. Don't know why I went along with their statement. It should be more than apparent. Perhaps they offered this up before these North Creek coils were introduced. Not sure when that was, but the last time I bought North Creek coils(1996) their largest wire gauge was 12. I am not a fan of the Solen heptalitz coils, I find North Creek much better sounding. And the Goertz would give a sound of another color, whether it is preferred is a matter of personal taste. I will need to check out North Creek to see how expensive these larger gauge coils are. Again, by running the mids flat out, I can save that expense.
I know that I prefer the sound of the mids without a coil in the circuit. Presuming that the driver is of the requisite quality and robustness, it is a no lose proposition. I would like to hear an argument as to what a series network could offer over having nothing in the path of the midrange.
I would not install more than two midranges in each speaker. As you pointed out, the cost of going crazy in this area adds up fast. I am leaning towards the two midranges, despite my liking the time alignment(one midrange) my Coincident speakers feature. Their sound has more than sold me on the arrangement.
Accuton drivers are not new. I first came across them in the early 1990's. While I didn't spend a lot of time with them, I can describe the sound as very smooth and natural. While pricey, they are not as expensive as Raven. I would not use Accuton drivers in this project because they are lower in sensitivity(usually 88 - 90 dB/2.83 V), and are not physically robust. I used to work with alumina(electronic substrates, paste, and I also used to tape cast it), and while very hard, it is very brittle. I have seen these drivers shatter rather easily in a speaker that was involved in a move.
In researching the EMIT-B ribbons you recommended from Speakercity.com, I found the sensitivity was too low for this project @ 90 dB/2.83 V. Price is good at $40. What do you think of the sound? I have not been around an EMIT driver since 1988.
The Ravens are available in sensitivities of 96 and 98 dB/2.83 V. Very high, but they are very expensive. Not sure if I want to put this kind of money in a speaker when I will be doing the cabinet work myself. While I have no problem with the construction of the box, I have never done any finishing. If I am going to build an expensive speaker, I kind of think it deserves the "living room" look.
I will also look into Cabasse drivers. I once helped a friend in a D'Appolito project using these drivers. They feature some highly sensitive drivers in their line. Sound is fast, and clear. Maybe not as laid back as I might want. We'll see. Following along Sean's recommendation, they offer some horns, which I should investigate. 108 - 110 dB/2.83 V sensitivity. Interesting.
Needless to say, the diamond domes are out of the question. Maybe Liz Taylor would be interested...
I will check out Bottlehead.com today. Thanks for steering me to their site.
My only listening of Fostex drivers were in a speaker that had no grunt to me. Kind of shallow. Lively and able to play loud, just that I prefer a little more "blood and guts" to the sound. Maybe I am selling them short. Have you heard them in a better light?
I am on record at Audiogon of not being the biggest fan of Focal tweeters. They can play loud and clean, just hard on my ears. But, I have really been impressed by the sound of Osborn speakers, which use all Focal drivers. When driven by more sedate electronics, such as Electrocompaniet, I have to admit the sound is first rate. Their mids and woofers are right up my alley, however. Available in high sensitivity or high impedence versions. So, that is why I will probably go with them or Cabasse.
Again, this is a wonderful dialogue. Something about the speakerbuilding hobby that I can never get tired of. Thank you! |
Thank you Noquarter. You have graciously provided more information than I could ever expected. I am endebted to you. If you don't mind, I will get into contact with you at some point outside of this thread to further discuss some things.
You are absolutely correct in raising the issue of this being a secondary speaker project or a "statement". To be honest, I easily fall into this trap. I go way overboard. A very negative byproduct of my love of the speakerbuilding hobby. It is by far my favorite facet of audio. In fact, spurred on by my thinking of the past few days and your assertion, I discussed this with my girlfriend last night. This was supposed to be a secondary speaker. I really should just buy something along the lines of 4 Vifa 6.5" midranges and 2 Vifa D26 tweeters. Run the mids with nothing in the circuit, and connect a not overly extravagant film and foil cap on the tweeter leg. Throw them in a reasonably well constructed box, wire them up and call it a day. Perhaps, I should revisit that for this project.
But, I have still haven't ruled out doing something where I can build my speakerbuilding skills/experience further...
One of the higher sensitivity Ravens I was referring to was the Raven R-2(there is another). If I do decide to use one, hopefully they have not been discontinued. I did hear the Raven tweeter in a few newer designs from Acarian systems, and my initial impressions are quite favorable. If this tweeter really can offer me this detailed, yet smooth sound, coupled with this level of output, it is definitely something that would be on my short list.
Good points on the horns. That is actually what I originally envisioned. Aim for a sensitivity from 92 to 95 dB/2.83V.
As far as the Fostex drivers are concerned, I did visit the Madisound site. While they look good on paper, as I previously stated, my real world experience with them was in no way favorable. Yes, their sensitivity is high, and their operating range more than extremely broad. Just that if I am going to build or buy a loudspeaker, it better not sound like that. Able to play lively and loud, yes. But to my ears, along the lines of the way a clock or table radio sounds. No sock or punch. AT ALL. My hope was that you would have also had heard Fostex. To tell me whether what I heard was just a poor execution of the driver, or an affirmation of this being what it sounds like.
The fact that we view Focal tweeters in the same light shows me that we do think in parallel ways, at least in this area. And, also in our belief that a driver with no crossover should be better than one in a series network.
So far, the only speakers I have heard with the series crossover fresh in my memory is Roman Audio. Very, very impressive. Yes, this hyped up, patented DiAural crossover is actually just a series network! Just that it contains no capacitors. SonusFaber has supposedly used in the past with a tweeter, so how enforceable is the patent?
I also heard Fried a lot in the past, but would need to hear them with my current ears/mind, and with the type of gear I use.
Again, thank you. |
Hey guys, maybe we should start a club? Yes, loudspeakers and room acoustics are the first thing to take care of. I love "audio salons" who offer to come over and "evaluate" your room(because I couldn't possibly know how to set up an audio system), when they should have someone come in to evaluate theirs first. But, how about those rollerballs? Do the gold plated ones really sound better than the nickel? Kidding of course.
Sean, I remember us discussing Coincident drivers in the past. Are these the same drivers as those? From what I remember they were a Seas cone, perhaps in the P17 series. There is a chance I would be interested in them, but one of the goals of this project would be to build a loudspeaker that sounds(and is) different than my Coincident.
I am sorry that Israel didn't get back to you in regards to crossover design. From what you indicated, you felt that Coincident might be running those drivers flat out in the Super Eclipse. Any further thoughts on that?
Noquarter, my Coincident speakers are the Digital Master w/Troubass subwoofers. If you go to Coincident's website(www.coincidentspeaker.com), you can find the Digital Master in the "reviews" heading(Audio magazine, Feb 97). They are truncated pyramid(where the time alignment comes in) satellites that use the Troubass subwoofers as stands, ala Wilson WATT/Puppies, Verity designs, etc. Only they were aimed at the tube/SET crowd.
The midrange drivers are from the Seas Excel line, the P21 series(I now forget exactly which model, my apologies). A polypropylene 8" driver, with inverted butyl surround, phase plug, and according to Coincident a 5 1/2 pound magnet. Exactly mirroring your statements, the magnesium cone drivers were not appropriate in this speaker because of the ringing. Magnified in the 8" version, and even more so at this relatively high crossover point(for this size driver) @ 2 KHz. The tweeter is a silk dome. Crossover is a statement in simplicity; first order, a capacitor in series with the tweeter, and a coil in series with the midwoofer. The review's only criticism is the lack of deep bass, which is obviously not a problem in my setup as I use the(perfectly matched to the Digital Master and Troubador) Troubass subwoofers. 10" drivers in large, sturdy rectangular cabinets. The literature states that they produce 22 Hz @ 105 dB, with less than 1% distortion.
The sound is very impressive. Dark, pitch black background. Fast, very alive, yet powerful sound. More authoritative(to me) than more recent Coincident speakers. Not as SET friendly as the newer designs, however. Detail is excellent. Soundstaging is as good as I have ever come across. I have been around a lot of speakers, but these were the only ones I have ever come across that I immediately fell in love with and KNEW I needed to own. I have never again come across that feeling again, and am still completely crazy about them.
There is just something inherently "right" about the sound. Whether it is a result of the time alignment, well constructed dead cabinet, simple first order crossover, etc., or the sum of it all, it is an example to everyone in audio who thinks that the sound of the designer(via complicated designs and even more complex crossovers) can ever be better than the sound of the materials themselves. And while I may have thought I knew something about speakers, I really didn't know anything. Just go with whatever the parts offer you, stay the hell out of their way, and let them speak for themselves. That is as good as they will ever get. Another confirmation to me(it took me long enough) in seeing that simpler is better.
Your statements about the metal cones were all pointed out to me in conversations with Israel. I pick his brain as to anything he would change with the speaker. I wanted to take them as high as they would go. His belief is that the only change that can be made to improve the speaker is upgrading to the ScanSpeak Revelator tweeter("You'll think you bought a new pair of speakers"). My suggestions were the magnesium coned mid/woofer, upgraded coil, cap, and wiring(silver). He has never been enthused about any of these. I still maintain that a better coil(such as an 8 gauge from North Creek), film and foil cap, and better wiring would HAVE to make things better.
I also once asked what his opinions were about this speaker's use of an 8" midrange as being a detriment. To which he strongly disagreed, saying that the performance and speed of this driver are wonderful. That this is a favorite speaker of his, and that he would put it up against anything produced by anyone. I guess it is a bittersweet thing that his previous(very interesting) designs(cabinets and coincident drivers - where the company's name derived) are no longer produced because of the success of Coincident. Those cabinets just require too much work.
The Acarian speakers I heard the Raven tweeter was the Statement. But, also in a new smaller line(Exotica), which also feature Seas magnesium coned drivers w/copper phase plug. The Exotica was showed to me by Marilyn in a separate room(that wasn't being used) at the NY HiFi Show. I told Carl I liked the sound of the Raven in the Statement, but that $120K(?) was WAAYY over my head. Carl took Marilyn aside and spoke to her, then she told me to follow her. We talked for a while about the Raven and alnico magnets, and she made me promise to give the Exotica a thorough audition at a local dealer(in Philadelphia). At the audition I saw that the Raven held amazing potential. Well, in Carl's hands at least.
Elliot Zalayet carries so many products like this in his Long Island showroom. I used to see them when I went up there. Raven, Cabasse, Accuton, Focal, and Vieta drivers. He is a little offputting for some people, but he is really a super person to have in this hobby, very helpful and knowledgeable. 7 or 8 years ago, I asked him why these drivers weren't being used in high end speakers. His sanitized comments were 1) the companies were not as creative, and that audiophiles are not as knowledgeable(so they don't demand the drivers) as they both tell us and 2) these drivers are more expensive. Since then, basically the only drivers of these "unknown" companies that have surfaced in high end in any great measure were the Focals.
The Fostex drivers I heard were the 8" drivers, complete with "whizzer" cone. In a medium sized, vented cabinet, with no other drivers. Not a dead cabinet, and meant to be that way. A homage to the designs of the past, as these designs basically are. Pre HiFi. I kind of think these drivers may be perfect in that element. But, it isn't my taste. After hearing it, my impressions were that was what these designs basically were. A page from the 40's and 50's, when 35 wpc was astronomical. Loudspeakers needed to be efficient, and not demanding in terms of current. Bass was not in the equation(was there no power for it in those days?). The speakers played loud enough, and were not slow in the least. But, like I said, it had the sound of a table radio to me. Pretty much what people's systems of those days sounded like(such as my grandparent's stuff). Richness, if ever there seemed cloying, and not of the dynamics and punch we have come to expect from the past few decades. So, I wonder if this guy(a friend of my father) who built these speakers for his system did a poor job, or is it the Fostex? My father, who is a TOTAL bass freak(and solid state type), thinks they are the worst speakers he has seen someone put together in a long time("He should have just used 6 X 9 Jensens...").
I can certainly empathize with your search for drivers. I wish you luck in this project with the EMIT tweeters. I am also thinking I should take a flyer on them, great price. Maybe I could put together a monitor like you are also doing, and give them to my brother-in-law who NEEDS speakers in the worst way, but is unlucky in that he is married to my sister(who won't allow him to buy anything). A fun project to get the blood flowing again, nothing as serious as what you are building.
Is it me only, or do you also face these issues often? If only I could get this magnet with that cone, or that cone with that surround, that surround with this basket, or that impedence, the list goes on and on... Jokingly I say that it's just like car companies. When they come out with a new model I have been waiting for, I have to wait another 3 or 4 years before the stuff I want is available in it. Either that, or they redesign the car all over again before they get to what I want, or my tastes have moved on altogether. |
