wow this is a great thinking actually.
Let me see if I get this right....Have you tweaked the existing XO and got rid of the peak on the FST?
Then at this point, I would like to say...how come at B&W they have carried the SAME response for the last 10years? (I am referring to the first Nautilus to the Signature to down to the latest diamond) 😱😱
Please EXPLAIN as I am not understanding...there is no reason from B&W's side to do so!!!!
Let me see if I get this right....Have you tweaked the existing XO and got rid of the peak on the FST?
Then at this point, I would like to say...how come at B&W they have carried the SAME response for the last 10years? (I am referring to the first Nautilus to the Signature to down to the latest diamond) 😱😱
Please EXPLAIN as I am not understanding...there is no reason from B&W's side to do so!!!!
B&Ws crossover does inherently have a peaky nature but combined with the cabinets diffraction profile and knowing what the tweeters output is like, it is difficult to know if the high Q filter is necessary or not.
You're not understanding the world of audiophile engineering. Lots of companies pride themselves on building no-nonsense conformist equipment, this is to mean that they build to what research says sounds good. Musical Fidelity do this with electronics, KEF, TAD and Revel, to name a few, do this with loudspeakers.
Other companies decide to go a different route specifically to be different, either because they think their way is better, or because they want to be different on purpose. Wilson, as mentioned earlier on, do not design their loudspeakers particularly well in any direction and I am always baffled when I see measurements of their loudspeakers. Then there's the brigade of electronics designers who go some odd route in the search for perfection and end up creating a product that measures poorly for no good reason except that they wanted to give it a go. If these people have the financial backing to bring these products to market and the products cost a lot and look really nice then there will always be people who will buy into their idea of perfection and who like the look of said equipment. Pseudo-science and audio techno babble is very good at convincing the layman.
Some companies do like tailoring their products to have a 'house sound' and that very much is the B&W 800 series loudspeakers and they all sound similar across the range and have the same kind of wonky frequency response, poor off axis response and high innate crossover to the tweeter using a midrange drive unit far too big to work that high properly. This creates a loudspeaker that sounds a certain way, it is not completely neutral, nor is it completely accurate, but it's different. Don't get me wrong, there are certain merits to the design choices of the 800 series and this is also an example of a particular way of thinking (ie the high xover point to the tweeter) but B&Ws explanation as to why this works for their loudspeakers and not others, just doesn't hold up.
The odd thing is that B&W could solve pretty much all of their problems by lowering the xover frequency down to around 2kHz. This would even out the off axis response nicely and push the resonance of the FST far enough out of band so as not to be a problem. There is a myth perpetrated that basically follows the lines of - the ear is most sensitive to the region between 1-3kHz so if you place a crossover here it's going to mess up the sound more than if it's placed outside that critical band. This is technically true but this is only if the crossover is poorly designed and only if placing the xover at say 4kHz doesn't severely compromise other areas of the loudspeakers performance. DIY guys have traditionally liked to place xovers high, or have aimed to do so, because if they don't have measuring equipment and good CAD programs then it's easy to make big mistakes. If you create big mistakes at 4-5kHz then it's less of a problem than if you were to make a mistake at 2kHz.
B&Ws tweeter-in-a-pod design is literally the perfect platform to engineer an excellent crossover at around 2kHz because it allows you to move the tweeter forwards or backwards to ensure that the phase is optimally aligned. In fact they do this already for the 4kHz xover in the current 800 series.
B&W like simple xovers and if they did cross at 2kHz they'd need to use a 4th order acoustic target, rather than the 2nd order filter that they prefer. Once again this is user preference rather than engineering preference. If there is any audible difference between a 2nd order or 4th order filter then it is so insignificant as to be ignorable and the use of the 4th order filter, that would result in a significantly better designed loudspeaker, would certainly improve the sound of the loudspeaker way beyond what any difference between the 2nd or 4th order filter could account for.
If B&W did go the route of making their loudspeakers sound neutral then they would lose their fanbase and the following of people who do prefer a sound that errs towards something else. There is nothing wrong with them doing this and there is nothing wrong with people for liking a more upfront presentation, just as long as they know that what they are getting isn't perfect.
I do have an awful lot of respect for B&W though, I think their drivers are exemplary and their approach to cabinetry and its design is also brilliant. I just wish their design ethos towards crossover design etc shared the same level of engineering perfection.
5th your post is really explicit and well explains your position. At this point I can't say anything about it I don't have enough technical knowledge on speaker design to back up your statements.
From a B&W user, I can only say that I feel the 800 is a solid performer and I can tell you it produces a sound to die for and I am sure that other users of this speaker like Art could and have confirmed that.
I am with you that objectively speaking, the XO seems to be designed toward producing what you call a signature sound rather than pure exercise of technical expertise.
I am glad to try new solutions and I will be looking with respect and interest future developments that will be portrayed in this thread.
From a B&W user, I can only say that I feel the 800 is a solid performer and I can tell you it produces a sound to die for and I am sure that other users of this speaker like Art could and have confirmed that.
I am with you that objectively speaking, the XO seems to be designed toward producing what you call a signature sound rather than pure exercise of technical expertise.
I am glad to try new solutions and I will be looking with respect and interest future developments that will be portrayed in this thread.
This is the reason that so much acoustic treatment was need to make the N802 sound good in the two cases I referred to earlier. Of course, the right acoustics will always improve system performance. However, some speakers need it more than others.
The truth is that an accurate system often sounds unimpressive (think back to your teens when all you wanted was loads of bass and treble). Nevertheless, once you become familiar with the sound and performance of a system that is transparent, you will find little appreciation for lesser systems. The first thing that will happen is that you will easily be able to discern between good and poor recordings. But, conversely, it also means that there is a role for audio equipment that is not accurate, yet managing to make those imperfections from upstream tolerable (even unnoticeable).
I get the same results using 5th's zma but upon closer inspection there seems to be a disparity between Zaph's impedance plot and the zma file, which shows impedance at 20kHz to be 23 ohms. Zaph's plot indicates 11 ohms and when you use an equivalent curve the crossover response looks quite ok, so there's a better than even chance that 5th's data is incorrect.
I took an existing measurement (Zaph) of the FST midrange, loaded
it to a simulator, applied the baffle step, let the software calculate
the phase and used it in another simulator (Xsim) to try out virtual
XO filters.
I am not particularly interested in why manufacturer did what he did.
I can only guess. Maybe the augmentation of the bass response,
a certain design philosophy (gentleman among speakers). Their
reasoning is totally clear only to them.
I am positive the LP midrange filter does what the simulation
predicts with enough accuracy to get a feeling what is going on.
Now, I am not a proponent of modding everything at any cost, only
if the user is obviously not satisfied with the way it performs.
I am a DIYer that does not like to mess around with expensive
products just for the heck of it.
I am in agreement with 5th, there is good reason why B&W
made it the way it is and it does not have to do anything with
sound excellence.
A typical thing I would do is lower the XO point to about 2,5 kHz,
push up the midrange sound pressure to meet the two of the loud
woofers and see if the tweeter can be done the same way.
Regarding your question on FST 3,5 kHz resonance, it appears
a huge 22uF cap has introduced enough of a change to call it
an improvement over what it was before.
Interesting, I used Zaph's T/S parameters Le to calculate the inductive rise. I do not use passive filters in my loudspeaker so I had no real need for measuring the impedance of my own unit and had to simulate/calculate the impedance I posted. It's possible there's some error in LspCAD or more its that Zaph's Le value is calculated in a different way. I will post another zma when I'm at my PC later on today.
Wouln't it be best precision for modeling in XSim to sweep your real world FST as it sits in box and do it for both left and right.
Another good point and I agree with you on this too.
Regarding 5th statement, it would be interesting to know from B&W why they have done that specifically. It doesn't look like the peak on the FST is miss on their latest model as all the 800 series from Nautilus on have the same response basically.
It would be nice if there was a way to contact the designer and just ask as it would finally shed light on this subject 😎
I've just chucked a pair of Wilmslow Audio Prestige Platinums that cost me £3000 in preference for the B&W 683s £680 that they were supposed to excel over.
I like the B&W sound and the Nautilus midrange is a gem to my ears.
I like the B&W sound and the Nautilus midrange is a gem to my ears.
there you go...same experience I have, but I guess we are wrong!! Please don't listen too much with your ears....please before buying a speaker take a look at the frequency response and then you will know if you want to buy it or not!!!! 😱
Let me reiterate that I have limited knowledge on speaker design and I am just picking up on what said here, so my apologies in advance.
Collecting various ideas and approaches that have been suggested here, we can obviously convey on the idea that the simpler the crossover that achieves the job correctly the better is. This also implies that ideally, the difficult work should be done upfront i.e. on the design of the drivers and the proper cabinet around them.
knowing that B&W spends a huge amount of time, resources and efforts in designing their own drivers which are exemplary and their cabinets are also, but that unfortunately their crossover is not as good (which obviously makes me wonder because if a company wanted to screw up why going all the way out to design excellent drivers and cabinet to then mess up with a stupid crossover?), taking advantage of such good drivers and cabinet design utilizing a minimal crossover is probably a textbook design in my vocabulary.
Anyway, if a real model of FST on the actual cabinet is done like Brytt suggests which can then help creating the real simulated model and if peak on the mid region can simply be tweaked out by adjusting values on the crossover like Lojzek is suggesting, wouldn’t this be the ideal situation described above?
This way not only the frequency response can be made flat across audio band, but the crossover frequency can be maintained at the same point where is now which pushes it beyond the most sensitive area of the ears; this would obviously be a big plus not matter how good the crossover frequency is there no better than no crossover frequency.
What I am not completely sure about it is if it is possible to tweak existing topology to make response smooth and linear?
Again my apologize if I say incorrect things, but I don’t obviously master the subject.
Let me know what you guys think about my considerations.
Collecting various ideas and approaches that have been suggested here, we can obviously convey on the idea that the simpler the crossover that achieves the job correctly the better is. This also implies that ideally, the difficult work should be done upfront i.e. on the design of the drivers and the proper cabinet around them.
knowing that B&W spends a huge amount of time, resources and efforts in designing their own drivers which are exemplary and their cabinets are also, but that unfortunately their crossover is not as good (which obviously makes me wonder because if a company wanted to screw up why going all the way out to design excellent drivers and cabinet to then mess up with a stupid crossover?), taking advantage of such good drivers and cabinet design utilizing a minimal crossover is probably a textbook design in my vocabulary.
Anyway, if a real model of FST on the actual cabinet is done like Brytt suggests which can then help creating the real simulated model and if peak on the mid region can simply be tweaked out by adjusting values on the crossover like Lojzek is suggesting, wouldn’t this be the ideal situation described above?
This way not only the frequency response can be made flat across audio band, but the crossover frequency can be maintained at the same point where is now which pushes it beyond the most sensitive area of the ears; this would obviously be a big plus not matter how good the crossover frequency is there no better than no crossover frequency.
What I am not completely sure about it is if it is possible to tweak existing topology to make response smooth and linear?
Again my apologize if I say incorrect things, but I don’t obviously master the subject.
Let me know what you guys think about my considerations.
Yes, it is possible. For a total improvement the midrange LP filter
and the tweeter HP should both be modified, either for the same
XO frequency or for the lower one which would improve the
off-axis performance.
The FST midrange is a real gem, the driver is superlative and does very little wrong, even run without a filter it sounds surprisingly pleasant. Its upper breakup is very well controlled, it's only issue is the peak that we're harping on about.
It has extremely low non linear distortion, is very sensitive, has a large radiating area given the frequency range the driver is called on to reproduce and a nice light cone. This pretty much results in it having an effortless and highly detailed presentation. I certainly haven't found anything that comes close to the way the FST sounds.
Now onto the updated impedance file. Unsurprisingly this makes quite a difference. I had forgotten that Zaph's measured Le is usually quite different than the actual spec. Le is typically measured at a specific frequency and its possible that Sound Easy does it at a different frequency either way the updated ZMA has been attached.
For completion here is the updated transfer function based on the passive filter provided by B&W.
As can be seen this is far more in line with what you'd expect. The filter first counteracting the slight rising response of the FST and then adding in the required attenuation for the 2nd order 4kHz xover point.
Then here is an updated version of the series connected notch placed in parallel with the drivers terminals.
Its values are more attractive too! A much smaller inductor.
With regards to redesigning the crossover for the loudspeakers, as far as I am concerned the crossover between the bass and midrange is fine and does not need altering, its the xover between the mid and the tweeter that is less than perfect.
If one wanted a different xover to be designed then to do it properly you'd need to make a good set of measurements. The design guide I posted details exactly how to go about doing this. But briefly you'd need the combined response of both tweeter and midrange, then the individual responses for both the tweeter and midrange, properly gated including both magnitude and phase responses. Of course proper impedance measurements for the drivers would be necessary too.
It has extremely low non linear distortion, is very sensitive, has a large radiating area given the frequency range the driver is called on to reproduce and a nice light cone. This pretty much results in it having an effortless and highly detailed presentation. I certainly haven't found anything that comes close to the way the FST sounds.
Now onto the updated impedance file. Unsurprisingly this makes quite a difference. I had forgotten that Zaph's measured Le is usually quite different than the actual spec. Le is typically measured at a specific frequency and its possible that Sound Easy does it at a different frequency either way the updated ZMA has been attached.
For completion here is the updated transfer function based on the passive filter provided by B&W.
As can be seen this is far more in line with what you'd expect. The filter first counteracting the slight rising response of the FST and then adding in the required attenuation for the 2nd order 4kHz xover point.
Then here is an updated version of the series connected notch placed in parallel with the drivers terminals.
Its values are more attractive too! A much smaller inductor.
With regards to redesigning the crossover for the loudspeakers, as far as I am concerned the crossover between the bass and midrange is fine and does not need altering, its the xover between the mid and the tweeter that is less than perfect.
If one wanted a different xover to be designed then to do it properly you'd need to make a good set of measurements. The design guide I posted details exactly how to go about doing this. But briefly you'd need the combined response of both tweeter and midrange, then the individual responses for both the tweeter and midrange, properly gated including both magnitude and phase responses. Of course proper impedance measurements for the drivers would be necessary too.
Attachments
I understand lowering would improve off-axis, but I do think that having the frequency higher has a better thinking than having to listen to it off-axis. After all you want to listen to it, while sitting down and at a precise location. Having a speaker more directive is not a big deal as long as at the the listening position the speaker disappears from the soundstage and the placement of the instrument height and width and depth is believable, I personally don't have a problem with that.
If you consider the latest Tannoy Royal Kingdom which are $50K beautiful speakers are very directive too and reason is simply because they are trying to get as close as possible to wide band making the woofer work on a wire range of frequencies thus having no crossover artifacts on the audio band.
I think that not having the crossover at the most sensitive audio band, required intense work on the drivers to work well on more extended frequencies.
To prove that the peak on the FST has a wide impact, it would be useful to tweak the frequency response in order to optimize the response and see if the sound that comes out is as expected better or not.
If you consider the latest Tannoy Royal Kingdom which are $50K beautiful speakers are very directive too and reason is simply because they are trying to get as close as possible to wide band making the woofer work on a wire range of frequencies thus having no crossover artifacts on the audio band.
I think that not having the crossover at the most sensitive audio band, required intense work on the drivers to work well on more extended frequencies.
To prove that the peak on the FST has a wide impact, it would be useful to tweak the frequency response in order to optimize the response and see if the sound that comes out is as expected better or not.
So fifth you are saying that it would only require to design proper filter for the mid range, is that right?
You are also saying to do so a precise set of measurements would need to be taken on the actual speaker and drivers, is that right too?
I don't have much time, but you are convincing me to give it a try, if you want me to...and if you guide me I can make the set of measurements you need to redesign the XO.
Let me know.
You are also saying to do so a precise set of measurements would need to be taken on the actual speaker and drivers, is that right too?
I don't have much time, but you are convincing me to give it a try, if you want me to...and if you guide me I can make the set of measurements you need to redesign the XO.
Let me know.
Stefano,
what you are saying is that you want DIYers to teach you
how to modify your 24 thousand bucks speakers?
Remember what you said about cheap skates
Don't be one Kenobi, for the sake of R2D2!
what you are saying is that you want DIYers to teach you
how to modify your 24 thousand bucks speakers?
Remember what you said about cheap skates
Don't be one Kenobi, for the sake of R2D2!
What I am saying is that, I can give a try with a different cross over. The modification is not permanent as I would take the original midrange XO out of the plinth and put the new one and run a comparison. If this doesn't work out the speaker can be put back to the original condition.
Since I think 5th is a very skilled person and he seems is not talking out of his butt, I decided I can evaluate a new crossover for a listening test.
Since I think 5th is a very skilled person and he seems is not talking out of his butt, I decided I can evaluate a new crossover for a listening test.