My modeler showed that the ports were larger than the minimum recommended to avoid port chuffing.
To improve that aspect you couls bell the port mouths (and lengthen the port a bit to compensate)
dave
If you've already decided/committed, then just ignore this post. If you haven't, maybe you should take a look at this post. Techtalk Speaker Building Forum From Parts-Express.com Find the point they start talking about a MTM version, post #96, and you might find something else to consider. I have a pair of the original TM version. Very nice speaker!
Mike
Mike
Exactly what I was looking for. I've posted there. Looks like I'll be building a more proper crossover for these. I want them to sound as good as possible.
I'm pretty sure you'll be happy with these. Plus, as you can see, there's a lot of dialog going on about them right now. Chris is a great guy and either he or someone else will be able to answer all your questions. Also, you're not far from the next PE DIY show; Ft Wayne. Have Fun,
Mike
The best crossover is no crossover. The least intrusive XOs are outside of 300-5k.
Crossovers are evil -- one of the reasons a growing number of people are happy to live with the shortcomings of a 1-way speaker.
dave
There is a huge amount of discussion with reference to this, so just a summary.
An XO causes an electrical, acoustical & physical discontinuity in the speaker. The telephone band is ~300-3k, this is well esablished by the telcos as the critical range for voice reproduction. 2-4k is where the ear is most sensitive.
So you want to keep the XO outside 300ish to 5k-ish.
The acoustic & physical issues are directly related to the length of a wavelength (ideally the centre-to-centre distance at XO is <1/2 wavelength). Electrical is, in general, related to the order of the XO, how extended the drivers are beyond the XO point, and how the reactive load of the XO affects the performance of the amplifier.
A typical 2-way puts the XO right in the 2-4k range, the worst possible place. 2-ways that can push the XOs higher than that -- say 5k+ -- could really be considered almost FR + a tweeter. The best of them use the 2md order roll-off of the (well-behaved) midbass as the LP, and a 1st or 2nd order on the tweeter. Midbasses that go this high are lucky to get down to 50-70 Hz and will never produce a truly authortitive bass. This is exactly the idea behind the scheme i suggested. Since the tweeter covers 2 octaves at most, we call it a helper tweeter.
If we flip the idea over, we use a mid-tweeter + helper woofer(s). This puts the XO low, where wavelengths are long (hence it is easy to keep drivers well within that 1/2 wavelength), near the top of the range of this type of system (200-400 Hz say), the drivers are well-behaved so one can get away with a low order XO (ideal place to use a 1st order series). Below that it gets less expensive to just use a plate amp (a pair of the NHT/Foster surplus ones Jack Hidley is selling off are $70).
With the rapidly growing number of really capable FRs available today, this latter approach becomes much easier.
Going back to your original idea, 1 or 2 3" per side, + 1 or 2 helper woofers will get you a better system. And many of these FRs usable as midtweeters, in the right box, will get into the 40s, essentially a true 9 octave FR, so one can just leave off the woofer and add it later (or not)
Too bad CHR70s have been so popular (or that you don't like paper -- i prefer the EL70 to the CHR). Perhaps you can find a pair someone has on a shelf, or spring for a tarted up set (which i have)
dave
Hey Xtreme, welcome to the forums. I believe there was a specific reason this thread was moved to the FR forum. IF you're planning on succeedind with a two way or multi driver design, plan on building an existing design that's been tried, measured and tested.
As for Full range, there's a MUCH better chance for success than a 2way from scratch without measurements or modeling experience....that's theway the cookie crumbles.
Now you have to consider some things since this will be a desktop build, the way i understand it. Zaph and others when designing an XO don't take into account near wall and desktop operation, which will reinforce the low end and in most cases negate the need for baffle step, eliminating the need for the crossover components. Also many designs use drivers that DO have a wicked breakup mode in the top end which would require a notch filter....and some components. In you case, depending on the driver chosen, there's probobly no need. These are a gift for your father in law, who i would assune if he's like any other 50ish+ guy can't here a THING above 15khz, maybe even less. So look for drivers whose FR shows no significant anomolies up to 13-15khz. Now secondly, FR drivers have pretty poor off axis response high up and if this is a desktop build, one has only to toe them ever so slightly off axis to remove any remaining sibilence and when listening near field, slightly off axis is always an improvement with small drivers running high IMO as they do tend to beam a bit.
Now the problem of power handling and your want to use multiple drivers in an MTM configuration.....you're expecting too much from a small format driver. Consider building him a 2.1 system with a small subwoofer and a compact pair of fullrangers. The Dayton RS-100 is an excellent candidate here when crossed to a sub as it has solid LF performance to 100hz in a small sealed enclosure and it's clarity and HD are simply stunning for such a small format driver. I built a pair for a friend with the Ikea bowls and stands for desktop use with an 8" under the desk sub and it was really an excellent 2.1 system with vocals to die for. The Ikea bowls make for a quick and interesting built but will require a router for best results. I used two per enclosure to create a sphere and connected the two to a central piece of maple as an integrated stand cut to the same diameter on top save a 2" wide section 10" long left as the stand mounted to a base. Looked cool, sounded great, easy to build and pretty cheap to boot. Building a sub may be more than you wanted to spend but there's some great sub drivers on sale at PE with cheap amps available....justa thought.
As for Full range, there's a MUCH better chance for success than a 2way from scratch without measurements or modeling experience....that's theway the cookie crumbles.
Now you have to consider some things since this will be a desktop build, the way i understand it. Zaph and others when designing an XO don't take into account near wall and desktop operation, which will reinforce the low end and in most cases negate the need for baffle step, eliminating the need for the crossover components. Also many designs use drivers that DO have a wicked breakup mode in the top end which would require a notch filter....and some components. In you case, depending on the driver chosen, there's probobly no need. These are a gift for your father in law, who i would assune if he's like any other 50ish+ guy can't here a THING above 15khz, maybe even less. So look for drivers whose FR shows no significant anomolies up to 13-15khz. Now secondly, FR drivers have pretty poor off axis response high up and if this is a desktop build, one has only to toe them ever so slightly off axis to remove any remaining sibilence and when listening near field, slightly off axis is always an improvement with small drivers running high IMO as they do tend to beam a bit.
Now the problem of power handling and your want to use multiple drivers in an MTM configuration.....you're expecting too much from a small format driver. Consider building him a 2.1 system with a small subwoofer and a compact pair of fullrangers. The Dayton RS-100 is an excellent candidate here when crossed to a sub as it has solid LF performance to 100hz in a small sealed enclosure and it's clarity and HD are simply stunning for such a small format driver. I built a pair for a friend with the Ikea bowls and stands for desktop use with an 8" under the desk sub and it was really an excellent 2.1 system with vocals to die for. The Ikea bowls make for a quick and interesting built but will require a router for best results. I used two per enclosure to create a sphere and connected the two to a central piece of maple as an integrated stand cut to the same diameter on top save a 2" wide section 10" long left as the stand mounted to a base. Looked cool, sounded great, easy to build and pretty cheap to boot. Building a sub may be more than you wanted to spend but there's some great sub drivers on sale at PE with cheap amps available....justa thought.
I don't mean to contradict you entirely, but I'll share what I've learned recently.
There have been at least a dozen proven builds with these drivers over on the partsexpress forum in 1 or 2 driver configurations with the same tweeter that was recommended to me. These guys have tested these drivers in MT and MTM configurations. The one I'm going to be going with is a .55 cubic foot floorstanding box tuned to 39 hz yielding an F3 of 38hz.
These drivers are producing so much bass at such low frequencies that people have had to double check that their subs are indeed off when testing. It has been done, and the sub isn't needed here, although I do have one for use if need be. The thread containing all of this information was posted a few posts up.
I know a bit about "super tweeters." I definitely like the idea of using a horn loaded tweeter as a super tweeter, because a horn tweeter has a constant power response, but it's a big mistake to not attenuate the tweeter. Horn tweeters are often in the area of 94-96 dB SPl and small full rangers are way, way lower. Now some people think adding resistors is anathema, but if you are going to use a passive crossover (capacitor) then what's the matter with using resistance too. In fact I really like the idea of an adjustable L-pad for use with a super tweeter. Select the crossover capacitor/crossover frequency first then dial in the amount of attenuation needed.
One of my all time favorite super tweeters is the AUDAX TW74A/TW010F1
One of my all time favorite super tweeters is the AUDAX TW74A/TW010F1
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That sims nicely as a BR, but keep in mind that a floor stander with that little volume will be tall & skinny and in reality will be an ML-TL (mass-loaded transmission line) & not a bass reflex, so the BR sims go out the window (port (aka restricted terminus) will be different than it would if a bass-reflex, and it should be capable of more bass. Damping will need to be volume fill and ot just a lining of the walls. Further one will gan by taking into consideration a driver offset, and port at the bottom of the enclosure.
And as an MTM, the XO almost for sure falls into the critical range we want to avoid. As well, if these are to be used nearfield (as in multimedia speakers for a computer), even with drivers this size you typica;;y aren't listening far enuff away for an MTM to integrate.
dave
The L-Pad is one way to do it. The way i decribed is also valid. The tweeter is attenuated, but by being tricky.
As an example lets consider a tweeter that is 6 dB hotter than your FR and you want to XO it at 15k. A 1st order XO attenuates at 6 dB/octave so if we XO at 30k then at 15 k it meets up nicely at the XO point. Works really well.
dave
Typically a super tweeter is used at a slightly lower frequency, maybe 10-12KHz. 15KHz would be too high of a frequency for some of the guys with hearing loss. I'm pretty sure I don't hear past 15KHz any more, however my overall hearing sensitivity is still quite good.
Further it's not difficult to imagine a horn tweeter being even 10dB louder than many a small full ranger.
Your method leaves you with a rising response even off axis.
As you have to cross lower, you may have to take on a different strategy. i have successfully used it down to 10k.
Even the guys with hearing loss, i believe, can often benefit from extension beyond what the sin waves mention.
If the tweeter has a larger differential then you cross over higher. One local installation had the XO set at over 50kHz to get the T900 down to match the FE206eSR
On the last, 2 factors make this doable. The tweeters have a natural fall-off at the higher frequencies, and our ears get less sensitive this high up.
If it works for you great, if not try something else. I like to avoid L-Pads.
dave
Ok, so you've got a plan with a proven design that posts actual FR measurements, distortion plots at rated power, crossover phase and impedance. Sounds like you're on the path to success......Good luck with your build. One thing.....try to not ignore all of the sound info you've gotten from Planet and others here about MTMs, the intended XO point problems and the certain pipe resonances of a BR in that volume. These guys know a thing or two.
Ok, so you've got a plan with a proven design that posts actual FR measurements, distortion plots at rated power, crossover phase and impedance. Sounds like you're on the path to success......Good luck with your build. One thing.....try to not ignore all of the sound info you've gotten from Planet and others here about MTMs, the intended XO point problems and the certain pipe resonances of a BR in that volume. These guys know a thing or two.
With all the valid yet contradicting points made about this subject, I'd say build some of each. As you listen to them, you'll decide for yourself which points apply to your listening preferences. I have some of each and I like them all.
Mike
Ok, so you've got a plan with a proven design that posts actual FR measurements, distortion plots at rated power, crossover phase and impedance. Sounds like you're on the path to success......Good luck with your build. One thing.....try to not ignore all of the sound info you've gotten from Planet and others here about MTMs, the intended XO point problems and the certain pipe resonances of a BR in that volume. These guys know a thing or two.
I don't doubt that at all. I've learned a lot so far, and in the future, I will be learning even more as these won't be my first speaker builds.
I also picked up some 2.5" versions of the Dayton drivers I just listed to use in compact cubes for "cute" sound systems with a t-amp. Pictures to come of all the work I'm doing once I get started.
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