In the past I have had electrostatic speakers and a big enough room to suit them, but now the listening room that I am stuck with is too small for them and I need some kind of near-field monitors with similar sound qualities to take thie place.
I am looking at using the Accuton C44-8 2" ceramic dome driver as the midrange, with C12-6 1" ceramic dome tweeters. Has anybody out there built or heard a speaker system that uses these two drivers? Can these or any other relatively compact dynamic drivers produce as convincing a soundstage depth and breadth as well-tuned electrostats?
I am looking at using the Accuton C44-8 2" ceramic dome driver as the midrange, with C12-6 1" ceramic dome tweeters. Has anybody out there built or heard a speaker system that uses these two drivers? Can these or any other relatively compact dynamic drivers produce as convincing a soundstage depth and breadth as well-tuned electrostats?
Looking at the specs, the C44 is practically a second tweeter rather than a midrange. When I make my next pair of speakers (I keep saying that I will, but I'll get around to it one day), I intend to use the C79 for the midrange. Its frequency response goes low enough to be able to use a large-ish woofer for all of the bass, rather than a premium midwoofer + subwoofer.
Just an idea: for a small room you might want a mono "centre woofer" for the bass: crossed over at ~300Hz and playing down to whatever low frequency it can handle. That way the monitors can be kept down to a reasonable size without too many sacrifices.
What are your past diy experiences? I made a 2.1-way system with the C23 and the C94 speakers, and that was tough work. You'll need to design the crossovers and enclosures to much higher standards than is necessary with most speakers. But remember, expensive capacitors and inductors a good crossover do not make; design made well and chosen parts for wise reasons do a good crossover make. The same goes for enclosures.
CM
Just an idea: for a small room you might want a mono "centre woofer" for the bass: crossed over at ~300Hz and playing down to whatever low frequency it can handle. That way the monitors can be kept down to a reasonable size without too many sacrifices.
What are your past diy experiences? I made a 2.1-way system with the C23 and the C94 speakers, and that was tough work. You'll need to design the crossovers and enclosures to much higher standards than is necessary with most speakers. But remember, expensive capacitors and inductors a good crossover do not make; design made well and chosen parts for wise reasons do a good crossover make. The same goes for enclosures.
CM
i'm planning to use the C23 (together with a C-Quenze 18H52 crossed around 2500 hz. Subbas will be Lambda SB12).CeramicMan said:
What is so difficult with the Accutons with respect to filtering?? Cone breakups?
Cone breakup isn't actually bad at all, especially as I made the crossover 3rd-order at 2.75kHz. If I had made active 4th-order crossovers with notch filters, that would be even better IMO.Duck-Twacy said:
Some people can never get used to the sound of my C23 tweeters. They're used to silk dome tweeters that project their limited 91dB/W output in a narrow spotlight-beam straight ahead and a lot of music is mixed with such speakers in mind. The Accutons have wide dispersion, so consequently people are hearing a lot more treble than they're used to. This is after I used an L-pad that muted the tweeter by a few dB to compensate for driver sensitivity, impedance, and parasitic coil resistance in the woofer's crossover section. Ie: I made it totally flat and accurate and for some it's still too bright.
The other aspect to consider is the type of crossover. I went with a Butterworth crossover, because it produces a "flat total power" output response rather than the L-R "flat on-axis" response. The Accutons have very wide dispersion which makes it pointless in most situations to optimize the on-axis sound at the cost of the off-axis sound. Also, to get a flat on-axis response with L-R crossovers you need perfect phase-alignment at the crossover frequency, which can't be easily done considering that the drivers and boxes normally have large phase differences even without any crossover. The Butterworth crossover is almost certainly another reason why some people think the speakers sound too bright, but I think it produces a very natural "live" sounding sound. Something to think about.
Because Accuton cones tend to move as pistons rather than the "water ripple" movement of most other speakers, I think they're more susceptible to problems with amplifiers that have a high output impedance, and more susceptible to box-colourations (but not cone colourations). A passive crossover will add to the output impedance of the amplifier and reduce its control over the speaker's cone. By itself I don't think it makes any difference, but it might make a difference when you consider that the amplifier has to prevent internal box resonances from adversely moving the cone. I've found that internal box resonances are audible above the clarity of the speaker itself. To reduce this next time, I'm working on the following principle: allow a huge box volume versus cone area for the midrange, and optimize the enclosure materials for the frequency range they need to work at.
CM
Thanx for your reply. Lots of valuable info. 2.75 should also be possible i.c.w the C-Quenze.
I am used to listening to old model Focal TW120K tweeters, so I'm used to a little bright sound.
I am used to listening to old model Focal TW120K tweeters, so I'm used to a little bright sound.
CeramicMan said:
Thanks for the input CM. My idea is to use the C12 and the C44 to cover the frequency response from 1kHz up. I am particularly attracted to the fact that the C44 is a closed-back driver and will not require a box to deal with any back-wave tuning.
When I have used C12 or C23 drivers in the past, I found that they were hard to get to blend-in seamlessly with drivers from other manuacturers, even with hand-tuned18db/oct Butterworth xovers and optimized midrange driver/enclosure/xovers.
Because there is so much overlap in thier respective usuable frequency responses, I am hoping that I could get away with only having to use 6db/oct xovers if I used C12, C44, and C89 drivers to get all the way down to 200 hz. I have a pair of Legacy subwoofers with dedicated high current amps and 18db/oct adjustable frequency active xovers that I have been able to crossover as high as 200hz in the past when I had the room to use Audiostatic 100s. This subwoofer system is very fast, without a trace of heavyness, boxiness, or boom.
The soundroom I have to work with now is only 13 X 14 and that doesn't leave me with enough floor space to continue to use the electrostats that used to work so well for me. I'm looking to build a pair of box speakers that will sound great sitting on top of my subwoofer cabinets, about 3.5 feet off the floor and 2 feet out from the rear wall. A pair of the long-ago-discontinued RTR ESR-15s would probably suit me just fine.
What do you think? Should I be looking at the Raven drivers instead?
lwr
A C88
lwr said:
Oh gy mosh! How much is that going to cost you?
I think one problem with your planned system would be the crossover network. I've got only limited experience with 6dB/oct crossovers, but when I've had the chance to compare them with 12dB/oct or steeper ones I've preferred the steeper ones. The differences are annoyingly subjective: to me the 1st-order ones sound a bit "mushy", but I can see why some people prefer them. What happens is that the sound comes from 2 sources over a relatively wide frequency range, which gives that "multiple speaker" effect. This is similar to subjective observations that mono music can sound better when played from several loudspeakers rather than one. However, when changing the crossover to a 3rd-order type, to me the speakers sound more "sophisticated". Imaging is improved, and with the Accutons you get a stronger feeling that you can "point to them" with your eyes shut. As a friend once said "the sound from the speakers is right there".
I'm not sure if the old 5" Accutons are particularly great. Both the waterfall and frequency graphs look better on their bigger 7" range, which I suspect is because they're newer. They've got a new C82 5" speaker, but I haven't found any specs for it yet.
I was recommending the C79 midrange, but now I don't think I know which is better: the C44 or the C79? Both have certain advantages over the other. What caught my eye however was that the C44 can be used up to over 10kHz, which is good but almost ridiculous. You could use a 1st order crossover, but I'd still recommend a higher order one.
Here are some options that I would consider:
C12 - C44 - midwoofer - subwoofer
C12 - C79 - woofer
C12 - C79 - Eton or other high-reaching subwoofer
C23 - C94/other high-reaching midwoofer - subwoofer
C12 - C44 - C220/Eton woofer/Seas woofer/other high reaching woofer
I don't know much about Raven ribbon tweeters. Previously I decided against them because of the less than perfect dispersion characteristics, the low damping factor with ribbons, and I wasn't convinced about the lack of colourations. The ribbons are fixed at the ends so they can't really move as one piece. The dispersion characteristics of various ribbon tweeters suggest that there must be at least some resonances. A major selling feature of ribbon tweeters is their high sensitivity, and this makes it hard to judge the other less publicised aspects of sound quality.
CM
I appreciate your comments about the liklihood that relying on first-order xovers, even among drivers that can play together nicely, is likely to smear the stereo image. I had not considered that possibility. I have always preferred third-order xovers but I have always thought that it was simply because they more rapidly attenuate the problem of driver resonance in the octave or so after the knee. In exchange for all the money that I was spending on extremely smooth drivers, I thought that I'd be saving quite a bit on only having to use first-order xovers.My interest in the Raven driver revolves around its excellent reputation for resolution of detail, "air," and broad frequency response. I was not aware that it may have unstable dispersion characteristics.
I appreciate your suggestion of using a C12 and C82, assuming that the C82 specs are consistent with the performance of Accouton's newer 7" drivers. When can we get the specs, availibility, and pricing on the C82?
Do you expect that using a C12 and C82 drivers in a MTM configuration would be preferable to a TM configuration of a C12 and C92?
Didn't know about that C82
Here's what I could find
http://www.akkus.com.pl/glosniki/szczegoly.php?firma=accuton&model=C82-T8
Here's what I could find
http://www.akkus.com.pl/glosniki/szczegoly.php?firma=accuton&model=C82-T8
The 95dB sensitivity of ribbon type tweeters is probably achieved at least partly because the dispersion is horizontally just as wide, but vertically shallow, and thus concentrating the energy. The Raven tweeter becomes louder and louder approaching 20kHz, suggesting that due to its length the vertical dispersion becomes shallower, but I wouldn't call the dispersion unstable though.
The site www.e-speakers.com has really good pics of measurements for the Raven R1, as well as a .pdf datasheet. For the most part it looks fantastic, apart from some resonances between 8kHz and 13kHz. The colourful waterfall plot only has 20dB of dynamic range and doesn't show most of the resonances that are visible in the datasheet though. Those resonances could be responsible for the "air" that people perceive - because no live performance I've ever been to had an "airy" sound so it must be something artificial.
I'd have probably bought one of those (or a competing brand) if I knew what to do about the sensitivity. Undoubtedly it's realistic that higher frequencies are more directional than lower ones, but by how much? As for balancing the sensitivity, I didn't want to over-do it in either direction. I didn't want the treble to be too loud on-axis just to keep the overall energy level about right, but I didn't want it too quiet either. That's why I went with a hard dome tweeter that had wide dispersion - so I didn't have to worry about it.
CM
The site www.e-speakers.com has really good pics of measurements for the Raven R1, as well as a .pdf datasheet. For the most part it looks fantastic, apart from some resonances between 8kHz and 13kHz. The colourful waterfall plot only has 20dB of dynamic range and doesn't show most of the resonances that are visible in the datasheet though. Those resonances could be responsible for the "air" that people perceive - because no live performance I've ever been to had an "airy" sound so it must be something artificial.
I'd have probably bought one of those (or a competing brand) if I knew what to do about the sensitivity. Undoubtedly it's realistic that higher frequencies are more directional than lower ones, but by how much? As for balancing the sensitivity, I didn't want to over-do it in either direction. I didn't want the treble to be too loud on-axis just to keep the overall energy level about right, but I didn't want it too quiet either. That's why I went with a hard dome tweeter that had wide dispersion - so I didn't have to worry about it.
CM
Also, I don't think passive crossovers need to be that expensive. I used low-cost parts from a local electronics shop:
2 x 0.82mH, 2 x 0.22mH inductors - ~US$3 to $4 each,
and a large pack of 2uF stacked polyester capacitors for about US$0.15 each.
Expensive polypropylene capacitors only have benefits in certain specialist electronics apps, but not audio crossovers. The capacitors were at a good price considering that they were stacked multilayer ones rather than the spiral-wound ones that have higher inductance.
CM
2 x 0.82mH, 2 x 0.22mH inductors - ~US$3 to $4 each,
and a large pack of 2uF stacked polyester capacitors for about US$0.15 each.
Expensive polypropylene capacitors only have benefits in certain specialist electronics apps, but not audio crossovers. The capacitors were at a good price considering that they were stacked multilayer ones rather than the spiral-wound ones that have higher inductance.
CM
Thanks for the lead on the Accuton C82-T8. I have emailed Madisound for specs, price, and availbility.
lwr said:
Hey lwr,
Did you end up building your speaker with the Accuton ceramic drivers? Any feedback on the xo's and what sounded best?
I'm thinking about a relatively full-range 3-way using the Accuton C12 or C23 tweeter and C82-T8 mid, with a 10" woofer (possibly Eton or ScanSpeak 25W-8565-01) with xo points around 300hz & 3khz. It would be in a sealed box design and augmented by my very fast sealed box sub from about 40hz down. Any thoughts on the potential of this design?
Cheers from Down Under & Happy New Year!
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