Yeah, as a BR, not a good alignment, though I've had good luck with them in MLTLs once damped, though they tend to be quite big and of course very power limited with most drivers unless corner loaded.
Still, with a fairly efficient driver they can play louder than what folks in apartments or similar can tolerate. At a glance, it looks like ~75 L/35 Hz with a ~7.62 cm dia. vent. I currently don't have MJK's software loaded, so can't give you a likely cut length other than to start with ~8.9 cm and shorten as required or gamble with 5 cm.
To get good vent loading, it needs to be fairly tall, around 60", but need to factor in the desired average seated ear height to fine tune it.
GM
Still, with a fairly efficient driver they can play louder than what folks in apartments or similar can tolerate. At a glance, it looks like ~75 L/35 Hz with a ~7.62 cm dia. vent. I currently don't have MJK's software loaded, so can't give you a likely cut length other than to start with ~8.9 cm and shorten as required or gamble with 5 cm.
To get good vent loading, it needs to be fairly tall, around 60", but need to factor in the desired average seated ear height to fine tune it.
GM
??? Don't have any, i.e. by 'them' I meant its BR 'unfriendly' T/S specs.
Note that all sims done using T/S only affect the BW from its tuning to its upper mass corner [2*Fs/Qts] where it has faded out, so the cab alignment has very little impact on the driver's mids and none of its HF, ergo I don't need to know more about them than their T/S specs to come up with a viable alignment based on other drivers with similar specs me or others have successfully used in MLTLs.
GM
Note that all sims done using T/S only affect the BW from its tuning to its upper mass corner [2*Fs/Qts] where it has faded out, so the cab alignment has very little impact on the driver's mids and none of its HF, ergo I don't need to know more about them than their T/S specs to come up with a viable alignment based on other drivers with similar specs me or others have successfully used in MLTLs.
GM
This driver has been in Monacor's catalog for ages and ages. A good sign. I had a pair of much cheaper wideband drivers by Monacor, the SP-50X, which were really good. Not just considering the price. The SP-155X is a cult driver in some circles in Germany. It would at least be interesting to try out.
I had some good expériences with sp50x in tqwt .Lot of bass, good power handling, good sound overall but need a tweeter. My parents have them for more than ten years and they always like them. It s a cheap driver.
Tapered Quarter Wave Tube
See exemple 3, It is the one that I built.
Tapered Quarter Wave Tube
See exemple 3, It is the one that I built.
Again, based on a driver's upper mass corner [2*Fs/Qts], a 1.0 Qts is the T/S theoretical point of diminishing returns, but lacking such knowledge way back when I was most actively experimenting/building, I used TLs to damp what I now know were up to ~2.45 Qts drivers, though I've since learned that around a 1.4 Qts is the practical limit before resorting to OB.
GM
GM
So what sort of TL would be best for this driver based on the TS parameters?
Classic TL, Tapered TL (tapered at which end?), MLTL... ?
Looks like the Qts is about right for a TL, probably a tapered as I remember Bob Brines saying that tapered is better for >0.4 qts.
Classic TL, Tapered TL (tapered at which end?), MLTL... ?
Looks like the Qts is about right for a TL, probably a tapered as I remember Bob Brines saying that tapered is better for >0.4 qts.
I have to remove most of that theory stuff from my web site. It's getting pretty dated and there are lots of good advise available on line and in forums these days.
My current advise is do a straight MLTL using Pete Leonard's "Transmission Line" program. If that won't work, then try a tapered line -- positive taper for low Q drivers, negative taper for high Q drivers. Tapered TL's always have a bunch of high-order harmonic just below 1000Hz that are hard to make go away.
Bob
My current advise is do a straight MLTL using Pete Leonard's "Transmission Line" program. If that won't work, then try a tapered line -- positive taper for low Q drivers, negative taper for high Q drivers. Tapered TL's always have a bunch of high-order harmonic just below 1000Hz that are hard to make go away.
Bob
Thanks Bob! I have Leonards TL installed but have not tried it. I suppose a positive taper quickly becomes a BLH in some cases. If the negative taper is sectional then are the harmonics mitigated to a certain extent?
A straight MLTL will be quite big, perhaps a folded tapered, or do these suffer from the same resonance problems as classic TLs do?
A straight MLTL will be quite big, perhaps a folded tapered, or do these suffer from the same resonance problems as classic TLs do?
Nobody in their right mind does a classic ROT TL anymore. You are right that a positive taper pipe becomes, well IS, a BLH. A negative taper pipe can be folded. I did one for the Alpair A7.3 where the partitions are all at 90*, in the sense of a reverse Nagaoka horn. Try a high taper ratio and then fold it into a series of decreasing area parallel passages.
Bob
Bob
Yea, something like that!🙂 BTW the line is 38" long, the box is only 17" high. You are going to need a longer bigger line. Good luck.
Bob
Bob
Someone mentioned using a 60" line, I'm hoping to be able to get down to 40Hz or so (F6) is this reasonable with a driver with an Fs of 70Hz?
Having a minute to look at the SP-155X, I believe your expectations are unrealistic. It is a high Q, high Vas driver. Just looking at the picture on the product page, this driver was designed to go into a car door. Your best bet is to put it something like a 15l sealed box and cross to a sub at ~150Hz. Of course this driver is a good candidate for an OB, but there is no way you will get useful SPL below 100Hz. Sure it will work in a 60" TL, but once stuffed to remove harmonics you will essentially have an IB -- infinite baffle,
Your biggest problem, and why low tuned resonant cabinets won't work is that you run out of excursion around 100Hz and 5 watts. Yes, you can tune lower, but SPL levels will be unusable below 100Hz.
Sorry to rain on your parade, but this driver is not too good to be true.
Bob
Your biggest problem, and why low tuned resonant cabinets won't work is that you run out of excursion around 100Hz and 5 watts. Yes, you can tune lower, but SPL levels will be unusable below 100Hz.
Sorry to rain on your parade, but this driver is not too good to be true.
Bob
Ah well, it's probably just as well. I built a sealed enclosure for this speaker and thought it sounded OK. I wanted to try out something else to get better bass because this driver is so cheap. The cabinet will probably end up costing more than the driver in this case anyway 🙂 .
Thanks for the heads up at least!
Thanks for the heads up at least!
Well, the way I decide which taper to use is mostly the opposite of Bob's since to the first approximation, typical low Qt systems tuned low normally ideally require a small cab tuned with a large, long vent, so 'morphing' it into an inverse tapered TL makes sense to me.
Typical high Qt systems OTOH ideally need a large cab with a short horn vent [aka BLH, BVR], ergo MJK's original positive taper ML-TQWT seems reasonable, leaving constant taper TLs for medium Qt systems centered around a 0.4 Qt.
In reality, a constant taper often is sufficient for all but really low Qt systems if the driver has a high enough Vas to keep vent length reasonable in a BR since no matter what the alignment, 'BIB' rules in acoustics and system Q [sysQ] dominates cab net Vb in most cases.
As Bob has already noted, the cab will ideally need to be big to have any power handling at all down below Fs and can be whichever taper you want, though is high enough Q that it can be made out of cheap, lossy materials with minimal bracing for the driver to help damp its basic 'ringing'.
Me and some others like the open, effortless sound of such systems are capable of and are loud enough to bother neighbors in apartment or similar apps, but definitely need some form high pass protection [historically, TT 'rumble' filter or one octave or better adjustable EQ] for some music and most movies made after the late '60s.
GM
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