I’m looking for feedback from anyone who might have some real-world experience with:
1) The Morel MW166 (6”)
2) And higher Qtc sealed speaker performance
I’m putting together a sealed (not interested in ports) 2-way MTM using the MW166, but it’s got a pretty high Qts, right off the bat. Putting it into a 30ish litre box would put it at around 0.9Qtc. I’ve built a number of speakers but never any with Qtc > 0.7. So I don’t know firsthand what a higher Qtc sound like. Since it’s a 2-way design (paired with a ScanSpeak Classic D2905/9500), the Morels will be tackling both mids and lows (xover around 2000Hz). So transient response will be important. Is a 0.9Qtc going to be able to keep up on more complex passages or will I lose a lot of detail? I also won’t be blasting them, since it’s a home hi-fi application (i.e. never more than 50 watts and likely not even that).
My second question pertains to the Morel driver, itself. I’ve read through some posts that were not positive regarding Morel drivers. And I’m certainly open to alternatives. I can tell by the SPL graphs that I will be crossing the Morel over past its break-up point but just haven’t seen anything that better suites my need in terms of frequency response range.
Thanks!
1) The Morel MW166 (6”)
2) And higher Qtc sealed speaker performance
I’m putting together a sealed (not interested in ports) 2-way MTM using the MW166, but it’s got a pretty high Qts, right off the bat. Putting it into a 30ish litre box would put it at around 0.9Qtc. I’ve built a number of speakers but never any with Qtc > 0.7. So I don’t know firsthand what a higher Qtc sound like. Since it’s a 2-way design (paired with a ScanSpeak Classic D2905/9500), the Morels will be tackling both mids and lows (xover around 2000Hz). So transient response will be important. Is a 0.9Qtc going to be able to keep up on more complex passages or will I lose a lot of detail? I also won’t be blasting them, since it’s a home hi-fi application (i.e. never more than 50 watts and likely not even that).
My second question pertains to the Morel driver, itself. I’ve read through some posts that were not positive regarding Morel drivers. And I’m certainly open to alternatives. I can tell by the SPL graphs that I will be crossing the Morel over past its break-up point but just haven’t seen anything that better suites my need in terms of frequency response range.
Thanks!
Out in the open a 1.0 Qt sounds fine IME, but in room with near/at boundary gain best to either stuff to 'taste' or aperiodically load it or use EQ and/or a hi-pass.
No clue, don't keep up with the latest n' greatest, though from an acoustic loading POV do recommend using dual 8" in a 1.5 alignment.
No clue, don't keep up with the latest n' greatest, though from an acoustic loading POV do recommend using dual 8" in a 1.5 alignment.
A long, long time ago Martin Colloms did tests with loudspeakers with different Qts. If I recall the outcome correctly, for smaller speakers, <20 litres/0.8Ft-3, the audience preferred Qts of around 1.0 instead of the "textbook" 0.7. It is supposed to be one of the reasons why the LS3/5A (Qts 1.1) is generally liked.
I do not know where to find that publication or its detailed outcomes; neither do I know whether the methodology of the test was anything near acceptable.
I do not know where to find that publication or its detailed outcomes; neither do I know whether the methodology of the test was anything near acceptable.
I did build speakers with QTC of 0.9 and above, and it works in the right application (open air, or far from any wall).
But i think you can find much better and cheaper drivers than that morel for that application. I would rather use the Dayton RS180-8 in that situation. It goes lower easier (even in 30L sealed for 2), and ends up like that in a lower QTC (0.78) than the Morel, what makes it less dangerous to go to a one note bass (aka a peak in the bass response). Morel is good, but there is always something better in my experience in the class of the driver... And i'm sure other drivers also can do it better (but i'm to lazy to search).
But i think you can find much better and cheaper drivers than that morel for that application. I would rather use the Dayton RS180-8 in that situation. It goes lower easier (even in 30L sealed for 2), and ends up like that in a lower QTC (0.78) than the Morel, what makes it less dangerous to go to a one note bass (aka a peak in the bass response). Morel is good, but there is always something better in my experience in the class of the driver... And i'm sure other drivers also can do it better (but i'm to lazy to search).
You could try a series capacitor to acquire a third order alignment. These typically start with a tuning at Qtc=1,0 to 1,1. The series capacitor brings that down (the slope rises of course), you can model it till fc sits at about -3dB. Added bonus is a kind of LF protection of your driver. Think of values in the +100 µF's. With low cost foil caps these days this even is possible without electrolytics.
Hmm, Avast blocks this site's various malware and the web archive wants a donation to proceed, so anyone got a pdf/whatever of it?
The JK article is basically a review of filter theory and the impact of Q on LF response. Nothing new there.
The real question is how Qts between -say- 0.5 and 1.1 translates to subjective preferences. My own experience is that we should not at all be so hung up on the "magic 0.7" Qts value. YMVT.
The real question is how Qts between -say- 0.5 and 1.1 translates to subjective preferences. My own experience is that we should not at all be so hung up on the "magic 0.7" Qts value. YMVT.
In the past few years I developed a simple process for designing speakers. To select a driver I determine the SPL I require at the low frequency limit for that driver. From that I calculate the required displacement to produce that SPL at that frequency. I can then look at driver displacement specs ( Xmax * cone area) to determine what drivers have sufficient displacement. I then sort drivers with sufficient displacement to find the ones that require the smallest enclosure. Here's where the Q comes in. I like to size the enclosure so small that the first internal acoustic mode is above the operating range of that driver if possible. Designing with a higher Qb allows for much smaller boxes. Now a higher Qbox will result in more group delay at the low end and a higher F3. This was a problem in 1960 but not today. I simply get in winISD and add the Linkwitz transform to lower the box F3 to where I want it and lower the Qb to 0.5 or what ever I like for low group delay. It's a synthetic big box. The Linkwitz transform filter can be built with op amps or use a miniDSP digital crossover or load the filter into JRiver or equalizerAPO on the PC you use as your source. Now many people will read this and object that I am boosting the bass and will push the driver to its limits. Well, by selecting the driver with sufficient displacement in the beginning, that just does not happen. And of course the majority of drivers have no problem reaching Xmax at low frequencies within their power limits. All of this can be verified with the free winISD software before you buy or build anything. The attached spreadsheet compares several woofers. The desired Qbox can be set in column H, The displacment/box volume is in column AA. I sort on that. There is also a displacement / $$ to see if the dirver is a good price. There is another page in the sheet for computing displacement from required SPL and frequency. To summarize, you want a low Q for the best sound due to low group delay, but you can achieve that with equalization and a box designed for a high Q. If you have budget for Morel, you should look at Purifi drivers, as they are much better in my opinion. https://purifi-audio.com/ptt6-5w04-nfa-01/ I think Madisound stocks them. The SB 6" or the SATORI 6" MW16TX-8 also look great, and have larger Xmax.
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So I see....... 👍 Still, a good one for the ever increasing number of newbies 'cruising' through here. 😉
Thanks, everyone, for your feedback. The information was genuinely helpful! After some thought, I think if I wasn't building a 2-way speaker, I would be less concerned with the higher Qtc. I suspect GM is right that normally a higher Qtc isn't really inherently problematic. But I tend to be irrationally greedy about transient response and lower Qtc's in the midrange. I suspect you're still right, though. 🙂
I appreciate the Collom reference, for sure! A blast from the past. I remember reading some of his stuff back in the 90's, in particular -- including the article you mentioned, Boden. 🙂
Olsond3, your methodology is somewhat similar to my own. And I've used a version of it with a couple systems I built that incorporated a miniDSP. But your reference to Purifi got me looking again and I remembered I bookmarked the Satori MW16P-8 6", as an alternative to the Morel. I think I will likely go that route: smaller box, lower Qtc, and not all the weird break-up (though there's a peculiar little dip in Satori at around 1200Hz but it doesn't looks too problematic). The MWTX16-8 looks like a really nice driver, but buying 4 at that price point is a tad beyond my current build budget. And nice fricken spreadsheet, man! I think we would be friends! LOL I worked on something similar back in the early 2000’s with a MySQL database that I hosted on a local machine that did something similar (though not as robust as what you have crafted). Sadly, I never fully populated it (which wouldn’t matter at this point since so many of those drivers are no longer available) and have no idea what I did with that hard drive. And now I’m derailing my own thread. 🙂
Thanks again everyone for your willingness to share your knowledge and experience! You are appreciated!
I appreciate the Collom reference, for sure! A blast from the past. I remember reading some of his stuff back in the 90's, in particular -- including the article you mentioned, Boden. 🙂
Olsond3, your methodology is somewhat similar to my own. And I've used a version of it with a couple systems I built that incorporated a miniDSP. But your reference to Purifi got me looking again and I remembered I bookmarked the Satori MW16P-8 6", as an alternative to the Morel. I think I will likely go that route: smaller box, lower Qtc, and not all the weird break-up (though there's a peculiar little dip in Satori at around 1200Hz but it doesn't looks too problematic). The MWTX16-8 looks like a really nice driver, but buying 4 at that price point is a tad beyond my current build budget. And nice fricken spreadsheet, man! I think we would be friends! LOL I worked on something similar back in the early 2000’s with a MySQL database that I hosted on a local machine that did something similar (though not as robust as what you have crafted). Sadly, I never fully populated it (which wouldn’t matter at this point since so many of those drivers are no longer available) and have no idea what I did with that hard drive. And now I’m derailing my own thread. 🙂
Thanks again everyone for your willingness to share your knowledge and experience! You are appreciated!