Posted this on diyAudiojust curious what you guys think too:I'm considering a pair of bookshelves to pair with my LMS5400 subs. Planning of using a RAAL 70-20XR as a tweeter. Can someone compare/contrast theofferings such as:Accuton c173-6-096eAccuton c90-6-078Audio Technology C-Quenze 18 H 52 17 06 SDScanSpeak Illuminator 18WU/4741T-00ScanSpeak Revelator 18W/8531G-00Links belowWhich would you use with the RAAL 70-20XR? And why?I'm also open to a 3way as well to pair with the existing subs. Posted this on diyAudiojust curious what you guys think too:I'm considering a pair of bookshelves to pair with my LMS5400 subs. Planning of using a RAAL 70-20XR as a tweeter. Can someone compare/contrast theofferings such as:Accuton c173-6-096eAccuton c90-6-078Audio Technology C-Quenze 18 H 52 17 06 SDScanSpeak Illuminator 18WU/4741T-00ScanSpeak Revelator 18W/8531G-00Links belowWhich would you use with the RAAL 70-20XR?
And why?I'm also open to a 3way as well to pair with the existing subs. None of your links work.Have you modeled the crossovers?Selecting one driver such as the RAAL is a bad way to start a speaker design.First you set the parameters of what you want your speaker to do at a specified budget.Then you look for drivers that are promising for the task at hand.Then you determine the type of loading best for the woofer.
You model that. Then you model the crossover.I would say that ribbons are hard to work with and integrate with a woofer.
They are not inherently superior to dome tweeters and in many respects inferior.None of the manufacturers that I respect and believe to have integrity use ribbon tweeters. I think there is a good reason.Two way designs using ribbons are especially problematic. If it is bookshelves speakers you are planning then a three way speaker is a nonsense, as you have an extra crossover point. Crossover points always cause problems, no matter which ones they solve. So it is always a good idea to minimize crossovers.If these speakers are always going to be used with a sub, then a sealed or a labyrinth design with a -6 db point around 80 Hz is an excellent plan.
To design a three way speaker to meet those criteria is absurd. None of your links work.Have you modeled the crossovers?Selecting one driver such as the RAAL is a bad way to start a speaker design.First you set the parameters of what you want your speaker to do at a specified budget.Then you look for drivers that are promising for the task at hand.Then you determine the type of loading best for the woofer.
You model that. Then you model the crossover.I would say that ribbons are hard to work with and integrate with a woofer. They are not inherently superior to dome tweeters and in many respects inferior.None of the manufacturers that I respect and believe to have integrity use ribbon tweeters. I think there is a good reason.Two way designs using ribbons are especially problematic. If it is bookshelves speakers you are planning then a three way speaker is a nonsense, as you have an extra crossover point. Crossover points always cause problems, no matter which ones they solve. So it is always a good idea to minimize crossovers.If these speakers are always going to be used with a sub, then a sealed or a labyrinth design with a -6 db point around 80 Hz is an excellent plan.
To design a three way speaker to meet those criteria is absurd. In general significantly higher distortion than domes.They require generally require higher crossover points, and steeper electric roll offs. So the woofer to mate with them has to be chosen with great care. They are better used in three ways, where the crossover can be kept above 3 kHz.The dispersion pattern of domes is much easier to integrate with moving coil loudspeakers.The performance of many ribbons degrades over time, especially if high spl is used.They are less than ideal transducers for high powered and high performance loudspeakers.The extra expense of good ribbons is not worth it when compared to the cost of domes of similar or better performance. In general significantly higher distortion than domes.They require generally require higher crossover points, and steeper electric roll offs. So the woofer to mate with them has to be chosen with great care.
They are better used in three ways, where the crossover can be kept above 3 kHz.The dispersion pattern of domes is much easier to integrate with moving coil loudspeakers.The performance of many ribbons degrades over time, especially if high spl is used.They are less than ideal transducers for high powered and high performance loudspeakers.The extra expense of good ribbons is not worth it when compared to the cost of domes of similar or better performance. I have heard one Salk design with ribbon tweeters. In general I liked the speaker, but I thought the HF its weakest feature. However this may well have been due to under powering as it was demonstrated with a tube amp.Every designer likes his poisons in different flavors. You can learn to be skillful with any number of driver sets.
When it comes down to it, it comes to how well the total design concept is executed rather than the type of drivers selected.Dennis Murphy seems to have a liking for ribbons, me not so much.and here you go off the rails. There are many good reasons to go 3-way. For example, one wants controlled directivity, reasonable efficiency, and high output capability, in a narrow package. (Others should note, as TLSGuy stated earlier, the configuration of the speakers should flow from the design criteria; starting with a drive unit and trying to kludge a speaker together around it isn't a good idea.)Yes, probably a 2-way with a concentric or waveguide-loaded tweeter and a 10-12' midwoofer blended with multiple subwoofers starting at 120Hz or so is probably the optimal way to make music in most homes. But sadly many of us just can't fit mains that wide. So a 3-way with a 5' concentric driver or tweet loaded in a waveguide and 4-5' mid range and supplemental woofers, something like with the port plugged - is just about the only practical approach. Salk does great woodwork, but the driver choices he makes are often puzzling.
Smooth and even midrange pattern seems not to be a design criteria.The Phils are interesting. Dennis does the ribbon thing right by using a narrow midrange and effecting the crossover where (horizontally, at least; similarly even coverage in the vertical axis has not been shown to be as important) both mid and tweeter are basically hemispherical radiators.While the Phils would likely not be ideal for a very live room or for placement close to the sidewalls (due to the very wide coverage),I can see them doing very well in a deader room with a lot of space between the sidewalls and the speakers. Salk does great woodwork, but the driver choices he makes are often puzzling. Smooth and even midrange pattern seems not to be a design criteria.The Phils are interesting. Dennis does the ribbon thing right by using a narrow midrange and effecting the crossover where (horizontally, at least; similarly even coverage in the vertical axis has not been shown to be as important) both mid and tweeter are basically hemispherical radiators.While the Phils would likely not be ideal for a very live room or for placement close to the sidewalls (due to the very wide coverage),I can see them doing very well in a deader room with a lot of space between the sidewalls and the speakers.
I normally don't take vertical measurements, because I use concentric drivers. (Yes, cabinet shape does have some effect.) But I'd say if one wants to accurately characterize the vertical performance, one should take the same measurements one should take for horizontal off-axis. (That is to say, out to 90deg, but in intervals weighted towards the design axis.) Now, given that research has overwhelmingly not shown vertical polars to be highly correlated with perceived sound quality, one may rightly wonder if it's worth the effort.
I would avoid using any of the Accuton ceramic drivers as a 2-way midwoofer because they are known to shatter if they are driven at or near Xmax at low frequencies. The catastrophic puff of white dust that once was your expensive woofer would be briefly spectacular, but at that price, I expect something more robust.Maybe the Revelator could work with the RAAL 70-20, but unless you found some that 'fell off a truck', you don't have that option. The 6.5' Revelator might or might not work with a 2800 Hz crossover. I'm not sure. Why not consider a smaller midwoofer with a 5-6' diameter? It will also work with your subwoofer. Obtaining the RAAL 70-20XR is a non issue for me.
All this talk about the downfalls has me reconsidering it now. If i didn't take this route what dome tweeters would you suggest?
Accuton C158
There are many good dome tweeters available at a variety of prices. In general, the lower a tweeter can play without distorting, the greater the cost. This is true for dome or ribbon tweeters. So a lot depends on your choice of mid or midwoofer. How high the midwoofer can go without significantly loosing off-axis performance and without getting near its breakup range should be the factor that determines tweeter choice. That's why I suggested a 5¼' (roughly 15 cm) midwoofer instead of a 6½'.Have you heard a speaker with RAAL tweeters, or with any ribbon tweeters? What were they?
What did you think of them?Some people like them, some don't, and some have limited experience with one or a few ribbon tweeters, and then generalize much too much about them. You're better off if you hear them for yourself.You should take the previous comments about ribbon tweeters (in general) and the RAAL (in particular) with a large grain of salt.
A lot depends on just how smoothly a crossover hands off the sound from a mid or midwoofer to a tweeter. This has a very large influence on how 'good' a tweeter is perceived to sound. The devil is in the crossover details.
Having an adjustable active crossover, such as the Behringer, does not make arriving at those details any easier. Among DIY builders, Zaph's measurements are widely considered a good reference for comparing drivers. He knows how to use his measuring rig, and he has measured many if not all of the widely available drivers.Be aware that Zaph has a generally poor opinion of ribbon tweeters. Much of that is based on their high distortion levels when stimulated with low frequencies (low for tweeters). If a crossover blocks those low frequencies, then his distortion measurements take on a very different meaning.
Keep that in mind. Go back to first principles, because anyone who says 'use this driver' or 'use that driver' is an idiot.How 'live' is your room?How far will the speakers be from the sidewalls? From the wall behind them?Do you generally prefer a more 'spacious' sound or a more 'focused' sound?I would tend to use cheaper drivers if I were you, with perhaps some limits as to overall resolution but much easier-to-work-with natural response. Simply because you've not demonstrated the expertise listening and designing speakers that would make more expensive drivers potentially worth it. FACE PLATE: One of the big existing problems is the use of thick front plates, so common in true ribbon designs, which are then bevelled to minimize their acoustical influence. On the other hand, bevelled front plate act as a wave guide somewhere in higher kHz range, ruining the linearity, so that has not solved the problem yet.
RAAL’s unique front plates are very thin with no bevels, and our research brought us to the making of the zig-zag “acoustically invisible” front plate ribbon opening. The benefit is “non-wave guide”, seamless coupling or ribbon air loading to the open space, because of the “distributed parameter” edges of the opening.
Accuton C173
By that, we achieved the unmatched linearity in the upper kHz region and exceptionally “clean” impulse response. This post is way off track.Docks, this is your first project.You want a good bookshelf, with good power output, that will mate well with a sub and integrate easily.
Right?You want a first project with a high chance of success.You absolutely do not need to make this a three way no what another poster insists.Good speakers use the least number of crossovers possible and try and do the least damage with every one. This makes the acoustic responses of your drivers and the T/S parameters of the woofer paramount. What the drivers are made of and there mode of operation is VERY secondary.People who drone on about the properties of woofer cone materials etc. Have never designed and built a speaker that was any good.I have selected for you a woofer and tweeter that will mate well together and give you good power handling as a THX type arrangement crossing over to the sub at 80 Hz.You can crossover very happily in the 2 to 2.5 kHz range.I have not played with the crossovers, but something like fourth order for the woofer and second order for the tweeter will likely give you a nice composite fourth order response.However making a good crossover is the real art. I suspect that the woofer crossover may have to change orders.I think these drivers with a good crossover and a sealed alignment is capable of very good results indeed.If you want higher power handling and a better horizontal response with limitation of the vertical response, these drivers would make a very nice small sealed MTM.