I'm trying to understand why these B&W tweeters don't have that typical metal dome harshness? They sound alot like planar drivers with very detailed upper top end and never ever get nasty even at very high volume levels. I usually can pick up on the ultrasonic response peak by ear listening to the upper piano notes or cymbals but these things don't sound like they have any breakup mode even though they should. I don't have a good enough measurement mic that has the frequency respose to measure that high where that peak usually resides. Maybe the acoustic lense has something to do with this, suppressing it?
I have the same tweeters in my B&W DM580s. They have better midrange and top end than some $5000 speakers I've heard. I'm baffled by how much dynamic reserve these things have being a 2.5 way design. They are crossed over fairly high around 3.5k 3rd order, so that probably has something to do with it, plus they can play as loud as some larger 3 ways. I did rip out all the old electrolytic caps and installed PP caps which made a massive difference everywhere.
So I just wished I knew the secret to why these tweeters are so good. I have a pair of Thiel tweeters made by Seas that sound similar, but not as open and dynamic. I used to turn my nose up at metal domes, but these B&Ws converted me.
I have the same tweeters in my B&W DM580s. They have better midrange and top end than some $5000 speakers I've heard. I'm baffled by how much dynamic reserve these things have being a 2.5 way design. They are crossed over fairly high around 3.5k 3rd order, so that probably has something to do with it, plus they can play as loud as some larger 3 ways. I did rip out all the old electrolytic caps and installed PP caps which made a massive difference everywhere.
So I just wished I knew the secret to why these tweeters are so good. I have a pair of Thiel tweeters made by Seas that sound similar, but not as open and dynamic. I used to turn my nose up at metal domes, but these B&Ws converted me.
Attachments
Metal domes don't have to sound harsh: I used the Peerless DA25 in a two way designed by someone who knows their stuff and it has a more detailed sound than a similar priced Vifa silk dome; no harshness at all, and it will plays louder, too.
I suspect some of the perceived harshness may be due to crossover design; from all accounts, aluminium SEAS and Dayton RS domes sound just fine and have been used in many highly regarded designs.
Geoff
I suspect some of the perceived harshness may be due to crossover design; from all accounts, aluminium SEAS and Dayton RS domes sound just fine and have been used in many highly regarded designs.
Geoff
Crossover implementation is obviously important to getting the best out of any driver. The main thing I'm referring to regarding harshness is the extreme top end frequencies. Most people say that the sharp metal dome ultrasonic breakup resonance isn't audible, but i believe it modulates down into the audible range.
The thing is, you won’t notice the modulation.
Metal domes and soft domes differ in radiation pattern at high frequencies because the soft domes break up and start behaving as ring radiators. The metal domes obviously don’t up till their break up.
Metal domes and soft domes differ in radiation pattern at high frequencies because the soft domes break up and start behaving as ring radiators. The metal domes obviously don’t up till their break up.
I think the best tweeters are metal dome Beryllium
https://www.kjfaudio.com/wp-content/uploads/2019/01/Datasheet-T34B-4.pdf
https://www.madisoundspeakerstore.com/pdf/SATORI TW29BN-B-8.pdf
Scanspeak Illuminator D3004/6640-00 1" Tweeter Beryllium Dome
breakup is far outside our hearing range and also the music material doesn't contain these frequencies
https://www.kjfaudio.com/wp-content/uploads/2019/01/Datasheet-T34B-4.pdf
https://www.madisoundspeakerstore.com/pdf/SATORI TW29BN-B-8.pdf
Scanspeak Illuminator D3004/6640-00 1" Tweeter Beryllium Dome
breakup is far outside our hearing range and also the music material doesn't contain these frequencies
B&W usually crosses the tweeters at a very high frequency, 4KHz or the likes. At that frequency even a 10$ tweeter sounds pretty good, so any half decent one performs pretty well in terms of HD. What you associate to harshness is excessive HD (odd orders) from a too low crossover point, or too high output, or both.
The typical breakup from an aluminium dome is at 26KHz, and this isn't audible, at least if you aren't a bat. And it doesn't modulate down in frequency.
The same applies also to aluminium dome tweeters.
Ralf
I've tried lower crossover frequencies with these tweeters down into the low 2k area and they still sound great at higher volumes, but they're limited in xmax, so not good at lower crossover points for my needs. I've pushed these things well into their Fs area (around 1.5k) without any compensation network and at lower volume levels.They really work well up to the point lack of xmax presents itself. They do have ferrofluid so that may be partially why they can somewhat cope with it.
I know that metal domes stay pistonic until their breakup frequency while the higher internal damping of a soft dome will start breaking up at much lower frequencies. The ultrasonic peak is also partially caused by a phase error from sound waves traveling faster through the dome material itself and radiating from the tip of the dome before the air pressure being excited by pistonic dome motion arrives. That's why some domes (mostly metal but also a few cloth) have a small phase control disc in front of the dome.
Im not trying to spark an argument, but the whole point is I can pick out a metal dome blindfolded with 99% accuracy and this dome doesn't sound like a metal dome or even a soft dome. I still believe its the lack of dome breakup that makes the difference. If you dont believe me, try listening at a louder level to a well recorded triangle, claves, bells, chimes or other high pitched percussive instruments. That HF resonance will be excited by this and modulate with the audio signal. It sound like a cracking sound and badly tracking phono cartridge sibilance on top. (No, I'm not a dog or bat).
Comparing apples to apples, (at the same crossover frequency and output levels) most metal domes don't sound as clean, open and exciting as the B&W unit. Closest thing I heard was a one off pair of Focal 26mm carbon fiber domes. The resolution of the B&W dome is almost on par with some of the best planars I've heard and owned. I've been building speakers for 35 years now and have listened to speakers costing as much as a suburban property. No other aluminum, magnesium, titanium dome can touch it. Yes, they are that good. Maybe its the alloy they use... who knows? Just sharing my experience.
I'm going to take measurements soon to find an answer. I'll have to beg, borrow or steal a decent measurement mic ie, Earthworks TC50, Bruel&Kjaer, Schoeps etc that goes up high enough to measure any weird stuff. I may buy another one of these domes to sacrifice for science sake.
I know that metal domes stay pistonic until their breakup frequency while the higher internal damping of a soft dome will start breaking up at much lower frequencies. The ultrasonic peak is also partially caused by a phase error from sound waves traveling faster through the dome material itself and radiating from the tip of the dome before the air pressure being excited by pistonic dome motion arrives. That's why some domes (mostly metal but also a few cloth) have a small phase control disc in front of the dome.
Im not trying to spark an argument, but the whole point is I can pick out a metal dome blindfolded with 99% accuracy and this dome doesn't sound like a metal dome or even a soft dome. I still believe its the lack of dome breakup that makes the difference. If you dont believe me, try listening at a louder level to a well recorded triangle, claves, bells, chimes or other high pitched percussive instruments. That HF resonance will be excited by this and modulate with the audio signal. It sound like a cracking sound and badly tracking phono cartridge sibilance on top. (No, I'm not a dog or bat).
Comparing apples to apples, (at the same crossover frequency and output levels) most metal domes don't sound as clean, open and exciting as the B&W unit. Closest thing I heard was a one off pair of Focal 26mm carbon fiber domes. The resolution of the B&W dome is almost on par with some of the best planars I've heard and owned. I've been building speakers for 35 years now and have listened to speakers costing as much as a suburban property. No other aluminum, magnesium, titanium dome can touch it. Yes, they are that good. Maybe its the alloy they use... who knows? Just sharing my experience.
I'm going to take measurements soon to find an answer. I'll have to beg, borrow or steal a decent measurement mic ie, Earthworks TC50, Bruel&Kjaer, Schoeps etc that goes up high enough to measure any weird stuff. I may buy another one of these domes to sacrifice for science sake.
Last edited:
Well i guess things are relative. I have not been fond of any of the B&Ws for some time, the top in particualr being bothersome.
dave
dave
Here are some measurements of the 705 Signature, made by an experienced person.
Bowers & Wilkins 705 Signature loudspeaker Measurements | Stereophile.com
Bowers & Wilkins 705 Signature loudspeaker Measurements | Stereophile.com
I used to not even consider listening to any of B&Ws speakers. I always thought they sounded rough and edgy to my ears. I was given the DM580 speakers I mentioned and would have never considered spending any money on them or any other of B&W stuff.
What converted me is when I upgraded the crossovers. They changed COMPLETELY 180 degrees in character after that. These speakers audibly disappear and it sounds like you are listening to electrostats when focusing on the treble. This is obviously the tweeters. I'm hard to please with treble. In comparison, I think alot of the AMT driver craze is overhyped. Even though they measure well and look great on paper, they don't do it for me. They don't integrate well with other drivers and the vertical dispersion is horrible. They sound aggressive and rough to my ears and I can tolerate alot of volume, but very little distortion. If I had to lock my head in a vise to listen to music, I'd rather do so listening to a nice pair of Soundlab electrostats or Apogee Divas. Most other metal domes are the same to me. A close contender to the B&W dome is the Audax TW025 gold dome, but its useless to my ears under a steep slope 4k filter. The Morel CAT378 is great too, but it lacks resolution. I haven't listened to any beryllium domes yet with the exception of the old Yamaha NS1000 tweeter, so I can't comment on that.
Anyways, I mentioned all this as a comparison. I don't like the coloration you get with most dome tweeters, metal or fabric. Up until now, my favorite dome tweeters were the Seas T35C002s, but they don't have the extension up top. What they do have is that immediacy which most domes lack, even if they don't measure as well as other tweeters. The B&W tweeters are a needle in a haystack. By no means am I a fanboy of most of their stuff, but these domes don't follow conventional rules and wisdom.
What converted me is when I upgraded the crossovers. They changed COMPLETELY 180 degrees in character after that. These speakers audibly disappear and it sounds like you are listening to electrostats when focusing on the treble. This is obviously the tweeters. I'm hard to please with treble. In comparison, I think alot of the AMT driver craze is overhyped. Even though they measure well and look great on paper, they don't do it for me. They don't integrate well with other drivers and the vertical dispersion is horrible. They sound aggressive and rough to my ears and I can tolerate alot of volume, but very little distortion. If I had to lock my head in a vise to listen to music, I'd rather do so listening to a nice pair of Soundlab electrostats or Apogee Divas. Most other metal domes are the same to me. A close contender to the B&W dome is the Audax TW025 gold dome, but its useless to my ears under a steep slope 4k filter. The Morel CAT378 is great too, but it lacks resolution. I haven't listened to any beryllium domes yet with the exception of the old Yamaha NS1000 tweeter, so I can't comment on that.
Anyways, I mentioned all this as a comparison. I don't like the coloration you get with most dome tweeters, metal or fabric. Up until now, my favorite dome tweeters were the Seas T35C002s, but they don't have the extension up top. What they do have is that immediacy which most domes lack, even if they don't measure as well as other tweeters. The B&W tweeters are a needle in a haystack. By no means am I a fanboy of most of their stuff, but these domes don't follow conventional rules and wisdom.
Last edited:
Looking at your picture, I realised there is a small hole at the back of the tweeter. Does it vent into a chamber? Maybe that is the secret of it. I have a friend who accidentally blew his B&W bookshelf. I replaced the tweeters. It has a small pipe at the back to serve as a transmission line to stop the back wave.
They have always been quite anal about the backside (pun intended) of the tweeters. Maybe that is the key....
Oon
They have always been quite anal about the backside (pun intended) of the tweeters. Maybe that is the key....
Oon
I have the same speakers. They are amazing! I believe one of my mids is blown. I gotta contact B&W about picking up a replacement.
"Another common feature is B&W's excellent metal dome tweeter, flush mounted in a special 'D' shaped moulding for these models, which sports a soft plastics cover to smooth any diffraction tendencies." Gramophone
Attachments
Prove it. Use the original Dayton RS28 in both flavors, or the Vifa NE19 in fabric and titanium.
Brandon, I could not agree more. But for a complete and fair comparison fabric and hard-dome should i.m.o. be equalized to exactly the same pass- and stopband transfer functions plus levels. These outspoken views -that XDT2500 is earpiercing!- on tweeters without any filtering in the equation never cease to amaze me.
Have you measured frequency response? The reason why B&W is not harsh and has airy top is mostly due to frequency response.
Well thats a little hard to do over the internet.
If it helps explain it any, I do a lot of work on vintage and modern large diaphragm condenser mics. I can pick out a Neumann from a Telefunken or any other mic just by recording a triangle, bell or most any other higher pitched percussive instrument that has alot of overtones. There is an audible distortion which can be picked up by the ear which does not show up on the recorded wave form. It sounds like a snapping noise followed by the tone of the actual instrument. Picky Neumann TLM103 owners can vouch for this effect and its irritating even on vocals with sharp transients. Most engineers get around the problem by limiting bandwidth through the use of a mic with less top end extension or through an LP shelf. If you have a recording that actually has top end extension past 20kHz, try it out for yourself listening with headphones or really good speakers. The problem is there and clearly audible.
This effect applies to drivers as well that have strong breakup modes outside of their passband which includes most metal and/or hard dome tweeters and even some planar drivers. Its not as obvious on domes smaller than 25-28mm, mainly due to the breakup frequency being higher up out of the audio range than the larger metal domes - they remain pistonic up to higher frequencies.
If you state the breakup mode isn't audible by means of being down-modulated (IMD distortion), then why do manufacturers bother with phase shields and other devices in front of most metal or hard domes, attempting to attenuate or suppress resonance peaks? At a minimum, not having some sort of phase shielding can negatively affect frequency response, which is audible in itself, although technically not caused by the same mechanism. It is however a result of low mechanical damping (high Q) and the high speed unattenuated propogation of sound waves inside the dome itself. The resonance shows up in the pulse response curve as well.
No, the actual breakup frequency by itself can't be heard, but its down modulation with the rest of the audio signal can be. This affect is much more prevalent with recordings that reach past 20kHz and tend to excite the resonance mode, specifically instruments with lots of harmonic overtones. Trying to tell me I can't hear the difference between a metallic, cloth dome, soft, hard dome, etc is basically like saying their is no audible difference between low and a high mechanical Q drivers. You can definitely hear distinct differences between them and you dont need to have hearing that extends into bat territory. My 14 yr old son can hear it too with almost 100% accuracy. He doesn't have a highly trained ear but he knows what he hears based on my description. Its not at all a psychosomatic thing.
If your audio system is bandwidth limited to under 20kHz, you won't really notice the effects of resonance breakup, but if you have decent top end extension and listen to music that actually has overtones reaching into the breakup frequency area, you will notice when the breakup resonance is excited in a tweeter that has a strong breakup mode. It has nothing to do with having dog or bat like hearing.
It has nothing to do with being ear piercing, shrill, bright or anything else like that. The problem sounds completely different and only shows up on certain instruments and sharp transients. Most people wouldn't even be able to describe it even if they did hear it, mainly due to the fact they dont know what real live acoustical instruments are supposed to sound like.
These tweeters measure almost ruler flat from 3k to past 15k give or take a dB or so due to mic calibration errors. I measured them when I upgraded the crossover. I dont have my laptop online to upload pictures. Its my audio recording PC and I try hard to keep it clean from any internet junk so it wont get compromised.
A friend of mine have a pair of B&W 703 from the past and I am always amazed by how good they sounds, especially in the high frequency range as discussing here. They are not too sharp, not too dull, not distorted, not sibilant, not resonant, not ear piercing, they are detailed and natural, not like an electro-mechanical device at all. Maybe I don't have too much experience but I can't mention a totally same tweeter presentation from other speakers or drivers. Really strange.