Jccart, the distance to the mix position is about three meters. I listened to them in a much smaller room and imo they were coherent at about two meters, as long as the ears were pretty close to the same height as the horn.
The MHM format is less forgiving of the ears being off-axis vertically than the HM format, or a 2.5 way HMM format. But if you're going to do all of your serious listening with your ears at the right height anyway, imo MHM has a lot to offer.
The MHM format is less forgiving of the ears being off-axis vertically than the HM format, or a 2.5 way HMM format. But if you're going to do all of your serious listening with your ears at the right height anyway, imo MHM has a lot to offer.
If you want to do this properly ... there is a clear route for that. BIG Horn and wideband compression driver - or even a coax compression driver. And there is a "ready made" combination of exactly that from B&C:
https://www.bcspeakers.com/en/products/horn_driver_combination/1.4/16/ME464-464
There is even a fullrange design available with 2 15". I would prefer to make this at least active but it's probably a good starting point
https://www.bcspeakers.com/en/resources/suggested-designs
For super critical listening I prefer 3" dome midranges. But these drivers sound really good (I use DE360 in my living room) and I would probably prefer them over a super extreme detailed design for having fun and enyoing music.
And it will blow you off your socks for sure. 😎
p.s.: No, it's not particular cheap. But it solves plenty of problems very elegant without producing too many new ones. You save the midrange drivers + amps and get better control for off axis sound.
thanks for answering I've always liked the idea of mtm as the first pair of serious speakers I heard were this format . I worry that I won't like the sound of horn loaded hf as my understanding is that they focus the sound over a more narrow range than direct radiating tweeters so I'm concerned it might be a bit too hot on axis the only designs I've listened to like this are pa systems where you can't really judge critically and a mackie studio monitor which only used a waveguide and I found a bit too bright and silbilant .
kind regards James
Jccart, ime most horns sound best a bit off-axis, and for home audio personally I prefer a wider-pattern horn than the one in those studio monitors.
Studio monitors tend to have a "flat" direct sound, which to my ears tends to sound "bright", but it helps the mixing engineer shine a spotlight on any problems that need to be fixed. If the brightness you heard was due to the direct sound being "flat", that is under the control of whoever designs the crossover and is not necessarily inherent to the use of a horn or waveguide.
Studio monitors tend to have a "flat" direct sound, which to my ears tends to sound "bright", but it helps the mixing engineer shine a spotlight on any problems that need to be fixed. If the brightness you heard was due to the direct sound being "flat", that is under the control of whoever designs the crossover and is not necessarily inherent to the use of a horn or waveguide.
Maybe too late to the discussion. Had 8NDL64 - fine drivers, they measure well, but oh my got the motor noises. These are very ugly above 2mm and leak even through the cone and dustcap. Tried to help it on the spider but ended up selling them after three days. I´d look for either faital or interchange some efficiency for power input for better behavior of the speaker. To each his own of course. The new silicone spider strong drivers of B&C look tempting.
@Crashpc You bring up a critical point with some of the B&C neo 8s as well as other pro audio midbass. As you said about the 8NDL64, the 8NDL51 has a similar issue when playing sine waves free air through it at lower mid frequencies (100 - 500hz). Theres a lot of motor noise sounding like 3rd order HD. The odd thing is it doesn't show up nearly as much (if at all) with typical music, even playing the full LF through it. I've learned you can't judge the motor of a driver if its playing in free air. I learned this lesson the hard way with a very odd problem I once had with a driver that was noisy only when it was installed in an enclosure. This is when I realized how important it was to operate the LF driver in a cab to test the motor. The speaker needs to see the air load behind and in front of the cone to judge it properly. In most cases, only with open baffle situations is free air motor noise an issue. The manufacturer purposely designs some amount of restriction into the VC gap to force air through it at greater velocity for cooling purposes.
In the case of the 8NDL51, it isn't nearly as noisy installed in a sealed box. I'm also running 2 of them from roughly 200 - 700 hz, so that further reduces the problem.
In the case of the 8NDL51, it isn't nearly as noisy installed in a sealed box. I'm also running 2 of them from roughly 200 - 700 hz, so that further reduces the problem.
Listening experience is important! But best in your own room.
I detected over the years that I prefer very good off axis behaviour cause it makes the room sound more predictable and I often have mora as one listening position and want steady sound through the room. I also don't tune my speakers flat (studio and home) cuas it doesn't translate well in my dampened room (mixes get to bass heavy). I do a 3-6dB bass boost but let the highs linear to hear all the details for mixing. With some distance in a hifi setup this results to a falling hf curve at the listening position, so I also tend to keep it linear on axis.
Get REW and a good EQ software/DSP/Dirac and do your own tirals!
PA drivers often use the air moved by the membrane to cool the coil. So it gets pressed through the gap and through small holes - this can make noises.
For PA use this is a small price to pay. But for a high end speaker ... I don't accept it. There is also usually some mechanical loss going with these noises.
Once again - PHL is totally noise free. And the closed back 10" I found should also be fine with it's closed cooling concept and heat sink.
@IamJF The range I'm using the driver in isn't affected by the motor noise. Its only audible playing low end and detectable when playing pure sine waves or fundamental tones without harmonics. The 8NDL51 is extremely low in distortion and sounds better than many higher priced, purpose intended midbass drivers. I'd opt for hifi drivers if they had the bandwidth, power handling and sensitivity of these select pro drivers, but they dont fit the specs. I've tried a few PHL drivers before and wasn't in love with their overall sound. They have sharper peaks and more resonant suspensions, which are a worse tradeoff for me than out of band motor noise.
You are aware that without the excursion (= cooling) the power handling is a lot lower? And that the ends of the voice coil will burn to a crisp because they can't get rid of the heat? I've already said it several times, these high excursion drivers are excellent but for your use one of the worst choice you can make!
@profiguy
@IamJF
Indeed I am on the sensitive side of this, but I did try it in an enclosure and still didn't like it.
I am well aware of the motor noises being inevitable for cooling, now I am using hypervented RCF's that do quite some noises and whistle even, and it is still not as bad as it was with 8NDL64.
Mind you, the issue was identified as spider leakage. I cut one spider a bit and it was mich better, but of course it changes cooling and other mechanical/acoustical characteristics. Still, this driver is banned in my book.
Also, this is issue of noise ratios - if the 12NDL64/12NDL76 is the same, it is rather not that much of an issue, because these drivers are couple dB louder, masking the noise better. The "SNR ratio" of these is fine.
Anyways I changed my mind, and for my little usage I hope I settled on B&C 12FW76. Also does some noises, but it seems not too much and again the ratio of produced sound to motor noise is fine.
@IamJF
Indeed I am on the sensitive side of this, but I did try it in an enclosure and still didn't like it.
I am well aware of the motor noises being inevitable for cooling, now I am using hypervented RCF's that do quite some noises and whistle even, and it is still not as bad as it was with 8NDL64.
Mind you, the issue was identified as spider leakage. I cut one spider a bit and it was mich better, but of course it changes cooling and other mechanical/acoustical characteristics. Still, this driver is banned in my book.
Also, this is issue of noise ratios - if the 12NDL64/12NDL76 is the same, it is rather not that much of an issue, because these drivers are couple dB louder, masking the noise better. The "SNR ratio" of these is fine.
Anyways I changed my mind, and for my little usage I hope I settled on B&C 12FW76. Also does some noises, but it seems not too much and again the ratio of produced sound to motor noise is fine.
I usually vent spiders myself on some drivers with denser weaving. It helps alot as you found out yourself. The trick is to not go overboard thinking if a little is good, alot would be better. I punch out 8 x 3/16" holes with a hot soldering iron tip and apply some dabs of cyano glue to the edges. Testing my 8NDL51s didn't reveal any significant noise from 200 hz upwards with a swept 50w sinewave, where I'd use them. Perhaps the 8NDL64 is worse in this regard. I haven't tested this one yet.
I did some further tests over the weekend with the 8NDL51 in a small 15 ltr sealed box and 30 ltr vented tuned to 60 hz. In free air the driver sounds pretty bad under 200 hz but it cleans right up installed in either enclosure. The vent noise generated by 105 dB/1m 60 to 200 hz sine waves disappears into the noise floor almost 30 dB down on the sealed box and a few dB less on the vented box.
Mounted in a proper enclosure, the 8NDL51 sounds overall very clean and accurate. Free air is whole different story, but I found that even just with the air load of a large baffle itself, the excursion noise quiets down significantly by almost 20 dB. In absolute free air, held only in my hands by the frame without a baffle, it sounds pretty bad.
This driver was obviously not designed for OB use. The smaller vent holes in the back plate and behind the VC gap move air very effectively at higher excursion. I guess that's how this driver was designed to work.
Again. I can't emphasize enough how well this 8" does with all sorts of material. It just sounds superb. Some other drivers may measure better, but they don't necessarily sound better. I've listened to dozens of 8" midbass drivers and most of them don't hold a candle to the 8NDL51 in various aspects. I'd like to test the 8NDL64, but I suspect it will fair just as bad in free air. I also tested the Eminence KL3012LF to compare results with a larger driver, which barely made any noise handheld in free air under the same conditions as the 8NDL51.
Mounted in a proper enclosure, the 8NDL51 sounds overall very clean and accurate. Free air is whole different story, but I found that even just with the air load of a large baffle itself, the excursion noise quiets down significantly by almost 20 dB. In absolute free air, held only in my hands by the frame without a baffle, it sounds pretty bad.
This driver was obviously not designed for OB use. The smaller vent holes in the back plate and behind the VC gap move air very effectively at higher excursion. I guess that's how this driver was designed to work.
Again. I can't emphasize enough how well this 8" does with all sorts of material. It just sounds superb. Some other drivers may measure better, but they don't necessarily sound better. I've listened to dozens of 8" midbass drivers and most of them don't hold a candle to the 8NDL51 in various aspects. I'd like to test the 8NDL64, but I suspect it will fair just as bad in free air. I also tested the Eminence KL3012LF to compare results with a larger driver, which barely made any noise handheld in free air under the same conditions as the 8NDL51.
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I went through some other pro audio bass mids and did similar testing as with the 8NDL51s.
They all pretty much responded the same way if they had higher vent noise. As soon as the air pressure is balanced on both sides of the cone, any audible noise disappears or in worst case scenario is greatly reduced to the point it falls under the remaining noise floor. There are obviously some drivers which are worse than others, but all of the B&C drivers I checked out fell in line with my findings.
The main reason I went through my smaller midbass drivers to check them was due to Crashpc's post. It made me double check for any manufacturer changes made in their assembly procedures, which happen quite often without revision to their data sheets. Its never struck me to check these drivers in free air conditions with higher amounts of excursion, being the drivers I commonly prefer to use perform extremely well under commonly encountered applications falling in line with existing manufacturer data. Sometimes it helps just for learning purposes to double check your work. Otherwise you may never encounter newer, improved drivers or applications which challenge already known to be excellent drivers.
They all pretty much responded the same way if they had higher vent noise. As soon as the air pressure is balanced on both sides of the cone, any audible noise disappears or in worst case scenario is greatly reduced to the point it falls under the remaining noise floor. There are obviously some drivers which are worse than others, but all of the B&C drivers I checked out fell in line with my findings.
The main reason I went through my smaller midbass drivers to check them was due to Crashpc's post. It made me double check for any manufacturer changes made in their assembly procedures, which happen quite often without revision to their data sheets. Its never struck me to check these drivers in free air conditions with higher amounts of excursion, being the drivers I commonly prefer to use perform extremely well under commonly encountered applications falling in line with existing manufacturer data. Sometimes it helps just for learning purposes to double check your work. Otherwise you may never encounter newer, improved drivers or applications which challenge already known to be excellent drivers.
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