Both of those drivers have worse distortion performance compared to the 2268 around 100Hz. The 2262 is already rolling off too much by 100Hz for me. So these are not quite as good as I am hoping to find.
Charlie,
Have you looked into speakers for (electric) guitar amps?
As a rule they are all >=95dB/W; 8 (or 16ohm); and importantly; they cover 80Hz to 5Khz, which means they should easily cover your 500Hz without much breakup, AND they are designed for open back (guitar) cabinets, which means they won’t make the cut if they whistle or chuff. Finally; they come in sizes like 10-15”, and really light but rugged (the show must go on!)
If you’re doing DSP or ASP; it should be trivial to equalise a flat response. The power rating is usually only 20-80W; but that’s enough to reach about 110dB/1m.
On the other hand, I don’t think I’ve seen the harmonic distortion performance; or even if they’ve been optimised for this.
Another more affordable option is the Tymphany FSL range of high sensitivity woofers; from 5.25” all the way to 15”…
Have you looked into speakers for (electric) guitar amps?
As a rule they are all >=95dB/W; 8 (or 16ohm); and importantly; they cover 80Hz to 5Khz, which means they should easily cover your 500Hz without much breakup, AND they are designed for open back (guitar) cabinets, which means they won’t make the cut if they whistle or chuff. Finally; they come in sizes like 10-15”, and really light but rugged (the show must go on!)
If you’re doing DSP or ASP; it should be trivial to equalise a flat response. The power rating is usually only 20-80W; but that’s enough to reach about 110dB/1m.
On the other hand, I don’t think I’ve seen the harmonic distortion performance; or even if they’ve been optimised for this.
Another more affordable option is the Tymphany FSL range of high sensitivity woofers; from 5.25” all the way to 15”…
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Thanks for the suggestion. I think you are correct in that the typical guitar speaker will have middling to poor distortion performance around 100Hz.
I am using this driver as the woofer for a nude open baffle system. This is just the driver itself suspended via wires in air. Because of the limited front to back pathway there is cancellation at low frequencies. The longer the path from front to back, the less cancellation.
The cancellation, which might be 12dB (more for smaller drivers, less for large ones) at 100Hz causes the apparent distortion to rise by several times compared to the "in box" distortion level. Thus, finding a low distortion large format woofer is very important. The rest of the system can be quite low distortion levels (e.g. on the order of 0.1-0.3 percent) and I would like to get the woofer down as low as possible, below 1% at 100Hz in my application. This only leaves a few "very low" distortion large (15" or 18") drivers as the most viable candidates (e.g. the 2268H). Distortion is often dominated by 3rd order (but this is driver dependent) otherwise I would consider two 12" or 15" drivers with one installed "backwards" (magnet facing the listener) to reduce the level of the 2nd order harmonic.
Since I will cross over at 100Hz the excursion demands are low, especially for the larger format drivers. Because the driver is open on both sides, many pro drivers that have a turbulent cooling system have some air-noise/chuffing sounds even at low excursion, so drivers with a single pole vent are better.
I was excited to find a 15" driver from Precision Devices touted as a low distortion bass/mid (the PD.153C0) but it seems that it is out of production now. Too bad, since on paper it seems to be perfect for my needs. I may have a lead on a new pair, but they will probably be unavailable in the near future and beyond.
I am not familiar with the Tymphany pro drivers and how they are positioned in the market so that is a big unknown for me. I would prefer to see some measurements before giving them a try.
Since it is very, very easy to measure the driver's 100Hz performance using a groundplane measurement my fantasy is that I am given access to the inventory of some place that sells pro audio drivers, where I can pull a driver, make a 2 min measurement, and the return it to stock. That way I can identify some winners without having to buy each and every one! For example at Parts-Express in Dayton, which is only a couple hours drive from me. But I doubt I will be given such an opportunity.
I am using this driver as the woofer for a nude open baffle system. This is just the driver itself suspended via wires in air. Because of the limited front to back pathway there is cancellation at low frequencies. The longer the path from front to back, the less cancellation.
The cancellation, which might be 12dB (more for smaller drivers, less for large ones) at 100Hz causes the apparent distortion to rise by several times compared to the "in box" distortion level. Thus, finding a low distortion large format woofer is very important. The rest of the system can be quite low distortion levels (e.g. on the order of 0.1-0.3 percent) and I would like to get the woofer down as low as possible, below 1% at 100Hz in my application. This only leaves a few "very low" distortion large (15" or 18") drivers as the most viable candidates (e.g. the 2268H). Distortion is often dominated by 3rd order (but this is driver dependent) otherwise I would consider two 12" or 15" drivers with one installed "backwards" (magnet facing the listener) to reduce the level of the 2nd order harmonic.
Since I will cross over at 100Hz the excursion demands are low, especially for the larger format drivers. Because the driver is open on both sides, many pro drivers that have a turbulent cooling system have some air-noise/chuffing sounds even at low excursion, so drivers with a single pole vent are better.
I was excited to find a 15" driver from Precision Devices touted as a low distortion bass/mid (the PD.153C0) but it seems that it is out of production now. Too bad, since on paper it seems to be perfect for my needs. I may have a lead on a new pair, but they will probably be unavailable in the near future and beyond.
I am not familiar with the Tymphany pro drivers and how they are positioned in the market so that is a big unknown for me. I would prefer to see some measurements before giving them a try.
Since it is very, very easy to measure the driver's 100Hz performance using a groundplane measurement my fantasy is that I am given access to the inventory of some place that sells pro audio drivers, where I can pull a driver, make a 2 min measurement, and the return it to stock. That way I can identify some winners without having to buy each and every one! For example at Parts-Express in Dayton, which is only a couple hours drive from me. But I doubt I will be given such an opportunity.
It could be too late for Charlie, but there is a great gem for his purpose. It is a Celestion FTR15-3070C. The distortion from 100-900 Hz at 90dB is so great, smaller than 0.05% with dominant H2, almost no H3 with a small peak 0.1% at 200Hz. It has 95dB sensitivity at that range but begin to drop off at 120Hz and only 91dB at 80Hz on IEC baffle. The only downside is that its Fs is only 41Hz and sensitivity drop below 120Hz, and xmax is only 3mm which mean it can not be used in dipole subs. Price is also decent too.
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Do you happen to have any measurements on the 2268? I wish JBL would publish some curves on this driver.
I probably don't have the kind of measurements you would want, but some data is found here:
https://www.audioheritage.org/vbulletin/showthread.php?11346-2268H
Also, there is some useful info and data in the attached whitepaper.
Here are the TS parameters and other info:
JBL 2268HPL Specs:
- Nominal Diameter: 18″
- Power Handling (RMS): 800 Watts
- Power Handling (max) :1600 Watts
- Impedance: 8 ohms
- Sensitivity: 96 dB 1W/1m
- Voice Coil Diameter: 3″
- Resonant Frequency (Fs): 33 Hz
- DC Resistance (Re): 5.3 ohms
- Voice Coil Inductance (Le): 1.85 mH
- Mechanical Q (Qms): 3.8
- Electromagnetic Q (Qes): 0.39
- Total Q (Qts): 0.36
- Compliance Equivalent Volume (Vas): 11.58 ft.³
- Maximum Linear Excursion (Xmax): 8 mm
- Cone Material: Paper
- Magnet Material: Neodymium
- Overall Outside Diameter: 18.125″
- Baffle Cutout Diameter: 16.625″
- Depth: 8.875″
- # Mounting Holes: 8
I know - it's a really good driver IMHO.
Even still, I abandoned my search for these large format pro drivers. I was never totally happy with how they sounded in the higher end of the passband in which I was hoping to use them - up to 350Hz to 400Hz. OTOH if that was only 250Hz, it would not be a problem, but the light cones start to shout above there. For example I am using the 2268HPL nude in a system now and I have to cross it no higher than 325Hz. That's just a bit higher than I would like and it's still probably too high for that driver. My solution moving forward will be to use several smaller drivers, e.g. four 8" or three 10" home audio drivers. I will still carefully select the drivers for low distortion around 80-100Hz where boost will be highest.
I haven't tried it. HiFiCompass posted a review that looks promising. It would be a less displacement compared to three 10" drivers, and this is an important consideration for OB... but for sure it could work.
Large drivers that sound good into the lower 100s are a rarity, especially when you stick them in a ported box. I'm pretty happy with the B&C 18PZB100 used up to around 300. I was on the fence with the 2268 but decided on the 18PZB100 based on its performance in a FLH. Most 18s and even some 12s and 15s start falling apart 100 Hz +. I prefer an 8 or 10" in a horn for 100 - 500 Hz.
The quick test I use for large drivers is listening to them play free air from the side, looking for any weird induced artifacts. At a minimum you can usually hear air flow restrictions in the VC gap and motor venting problems. It sounds like a clipped type of square wave in the low end at higher drive levels with fundamental bass notes,
The quick test I use for large drivers is listening to them play free air from the side, looking for any weird induced artifacts. At a minimum you can usually hear air flow restrictions in the VC gap and motor venting problems. It sounds like a clipped type of square wave in the low end at higher drive levels with fundamental bass notes,
I had made an open baffle speaker using some MCM Audio 15” woofers. https://www.newark.com/mcm-audio-select/55-2963/15-die-cast-woofer-with-paper/dp/80R7008
They have a nice midrange roll off without being peaky like a lot of 15s. The qts is high enough for ob, (ignore published qts) and the fs is around 32hz. I have not taken distortion tests but they sound fine. They have very open cast frames.
They have a nice midrange roll off without being peaky like a lot of 15s. The qts is high enough for ob, (ignore published qts) and the fs is around 32hz. I have not taken distortion tests but they sound fine. They have very open cast frames.
This is a great driver. Not the best in terms of measured performance, but it sounds fantastic.
People often tend to judge professional drivers by (measured) performance, but I have yet to hear of a system with 'heavy duty' professional drivers that I would like to own myself.
The low xmax is just one of many interdependent factors inherent in the 'perceived' qualities. According to the respected German magazine "Hobby HiFi" it's one of the best midwoofers ever, regardless of price.