The consensus on the 5.25" was something like "even better than Peerless HDS in a SDS steel basket". The basket on the 4.5" somewhat reminds me of the SDS of that size, terminals are more like Wavecor... your guess is as good as mine.
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my tiniest speaker so far
- Thread starter agnostic1er
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I could as well, but not in 3.7l combined volume for subwoofer and midrange beating a midwoofer in a 2-way concept of the same volume. Maybe in 6 or 7l combined it is possible, will give it a try as some sort of xperimental spinoff if I find the time. By chance I have a driver meeting the requirements.
Excursion is the underlying issue and that increases with very little diaphragm area playing very low bass at reasonable SPL.
It is other way round: If you want the optimum from 3.7l net volume and your money, you have to calculate if one capable midbass for a 2-way concept gets you further, or dividing the chamber even more into woofer + midrange enclosure which leaves very little space for the woofer. A classic 3-way concept with comparably high x-over freq >400Hz lets you save space for the midrange chamber but does not really solve the IM issue for the woofer.
None of the concepts would play very loud/low nor retain clarity in case the woofer gets into the red zone. Which brings me to the conclusion that the 2-way would be the better way to go, just as the OP did it. I am ready to change my opinion straight away in case anyone can name a suitable combination of bass driver and midrange.
It is a philosophical question. And I agree that people who design loudspeakers with 40l of volume or more would not be facing such tough decisions.
But I feel that it is fun to accept such a challenge, and smaller speakers with a pleasant slim appearance are more likely to be accepted by music lovers who would otherwise not listen to loudspeakers at all. There is a legion of compact bluetooth speakers on the market which are sold and enjoyed in mass quantities. While I do not understand the point of the very slim, sub-1l models, I found several units offering about 1,5l of volume per channel (3l for stereo) which would satisfy the majority of listeners regarding bass, dynamics and max SPL capabilities. Would love to do something like that on a more sophisticated DIY level.
It is not really definable by the impedance nor the nearfield FR of the passive radiator, as the tuning is much below standard calculation given the parameters of driver and air. I prefer to take a look at the nearfield measurement of the woofer checking where the excursion minimum might be, and that is clearly 46 or 47Hz.
I believe the bass is adequate for such a small enclosure, Just a remark on the non-standard tuning of volume and passive radiators.
Do you mind sharing a picture please? I vaguely remember the 5.25" which I had to exchange years ago. It had a very huge shielding cap on the magnet and was still labelled ´Klein+Hummel´. No idea if this is still the same unit used in KH120. Probably not.
From the KH80 DSP teardown thread:
vs.A quick look at the drivers:
I must say, they look rather unsuspecting!
More details to follow.
Peerless by Tymphany SDS-P830855 4" Woofer 8 Ohm
Peerless by Tymphany SDS-P830855 4" Woofer 8 OhmTymphany's SDS Series 830855 woofer is intended for use in small surround sound speakers, compact monitors, as the dedicated midrange component in 3-way or 4-way systems, or even as a small PC subwoofer.The 830855 features a truncated cosmetic...
www.parts-express.com
No, definitely not. Not even the driver size if memory serves. The entire speaker has grown a bit since the days of my O110s.
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It does by a factor of five, 2000Hz / 400Hz. Admittedly, clarity is a tiny bit improved going from 350 down to 250, anecdotally.
It keeps clarity, because woof and tweet are decoupled, anecdotally.
Not quite, just engineering.
I see, you cannot compete with those food-bucket designs. I was told they are carried to the restroom also, perfect versatility. Hifi is over. Strange, isn‘t it, that people first accepted surround 5.1 for some cheesy effects, and now have switched to mono. Today everyone is a fotografer, and a moviemaker, and a communication genius, worldwide. Music is boom tssss whoowee.
Never mind, only wanted to propagate some ideas. In particular, if Linkwitz is to be believed, IM originating in Doppler transformed to AM by room acoustics may be interesting enough to recap his formulas. See link above. Have fun!
OP
agnostic1er
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Thanks. The die-cast basket looks somehow familiar to me, but the rest I have never seen.
I would not solely rely on just one figure. How a speaker behaves in terms of clarity and transparency when being pushed beyond its comfort zone, is something not really predictable, and heavily dependent on the music material. I do not recall any ported and non-coaxial speaker showing audible signs of AM or Doppler when pushed to the limits, and effects I would prescribe to IM or temporal exceeding of the excursion limits are in most cases a lower midrange thing, not necessarily annoying at 2K. You have to take the whole behavior of the diaphragm into account, as between 100-250Hz small cone drivers usually tend to show heavy compression as a side effect, not just distortion, when kicked beyond their limits. All this melange would still be audible in a ´classic 3-way´ with higher x-over.
Would not say that. Such drivers and passive radiators are freely available, maybe even better ones if your budget is higher. You just have to find the right one for your given concept, as many drivers on the market tend to be outdated or meant for a different purpose, like bigger vented boxes.
You surely cannot produce cabinets with both stiff and super-thin walls yourself, but that is a minor downside. The rest is a matter of a clever concept putting some time into optimizing x-over, bass boost and bandwidth-limited compression. You have to know the frequency bands in which your concept will reach its physical limits first, which with a passive concept might happen at pretty low SPL.
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Sealed mini speaker, 3-way
Question is, were they successful? I can't really answer that. Anecdotally, I showed them at a meet and was quite surprised that they were very well received. That's why I asked which measurements should be made and for what purpose. What should they say in terms of preference by a single...
www.audiosciencereview.com
See the above link to an individual post on IM. If you don‘t feel, as an engineer, that there‘s something to be done, well …
Strawman? Dunno about such tendencies. Nonetheless I was talking about lower x/over anyway, that‘s why it has to be DSP.
Talking about ‚food-bucket‘ designs, mono, bluetooth to carry everywhere, driven by a smart phone of course, I cannot compete. These smart people using them don‘t accept my quality criteria as relevant; it‘s another culture. It is fine as it is. It‘s a pitty that there‘s no intersection I can see yet, but o/k.
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Re: Doppler distortion, this should be of interest:
purifi-audio.com
Doppler distortion vs IMD?
purifi-audio.com
The bit about headphones is, in fact, quite important. If you have any issues with combing (audio path interference, even if normally benign) or a decidedly non-flat response in the frequency range in question for other reasons, that would act as an FM discriminator and perform FM-to-AM conversion, thus muddling up the picture. So how important Doppler distortion should be to you would depend on your room acoustics.
Exactly! That piece was, actually, the reason to scrutinize the Purify (and other) concept of extending excursion. Without limiting bandwidth that is, see Linkwitz‘ formula above.Re: Doppler distortion, this should be of interest:
Doppler distortion vs IMD?
The bit about headphones is, in fact, quite important. If you have any issues with combing (audio path interference, even if normally benign) or a decidedly non-flat response in the frequency range in question for other reasons, that would act as an FM discriminator and perform FM-to-AM conversion, thus muddling up the picture. So how important Doppler distortion should be to you would depend on your room acoustics.
I feel a bit bad about high jacking this thread, if it is so. But we had unloading below the tuning frequency, and why with a tiny volume like this … sealed/closed, intermodulation, the smaller the better a three-way, and so forth.
It is said, that Doppler induced intermodulation has a special phase correlation. That would hinder the hearing to detect it. Phase correlation is destroyed by room reflections. That adds to simple FM to AM conversion.
Listen to the above mentioned demonstration over your (good) speakers in your room. Trust it! Or do you think they are that bad? Do something about it. Listen.
I try not to have feelings evolving from analyzing measurements. The audible outcome of nonlinear distortion of any kind is pretty difficult to predict, and definitely not result of just some figures appearing high. If distortion is increasing overproportionally with increasing SPL or something was detected in the listening test as annoying, it is another story and a reason to do something.
I have no real sympathy for monaural listening or taking a higher-quality speaker to the beach as well. But seemingly for a lot of people it is bringing them to music and a certain understanding of sound quality while on the other hand big companies such as Harman and Klipsch seem to put a lot of engineering brain into this segment. Particularly when it comes to getting satisfying bass out of 1.5 or 2l per channel, the results are stunning and there is something to learn from that for DIY and classic hi-fi.
Wasn’t talking about feelings exactly, but an intuitive urge to bettern something, that actually can be understood and improved. You didn‘t read my measurements, and not yet the argumentation and little calculations of S.Linkwitz?
Aha, ok. We see it from quite different viewpoints. From practical experience I would say that like 8 liters are a breakpoint. It works up to 96dB full spectrum peak if done (very) right, which others deny, and using tons of amplification. Below, that’s not musical anymore, in my book.
Thanks for giving me the opportunity to express my point (Linkwitz, etc)) and, promised, I won‘t spoil this discussion anymore.
With conventional drivers in either closed-box or vented designs I would agree. But in recent years, astonishingly capable miniaturized midbass sub-4" drivers have hit the market which fit into 2l or less equipped with a passive radiator or two. I agree, the OP´s choice is not ideal, but the concept is fascinating and doable.
Which one of these did you try?
96dB below 40Hz from 8l, might be technically doable, but the question is with which driver and if the effort is worth it. You really need a driver designated for such purpose (which is a rare thing), lots of passive radiator area and lots of amplification. And the question is if the result will be satisfying from lower bass quality point of view. I doubt that. Most of bigger drivers are not meant to be incarcerated into 6 or 8l and they sound strange below 40Hz with lots of boost.
96dB was meant as the peak sound pressure level, let's say over a period of 500ms for a broadband signal, bass + mids + treble that is. The demand is especially not meant to be focussed on a single bass note.
Not only has every bass note some overtones that contribute to loudness a lot, consuming a lot less capabilities in amp and excursion, but the mids contribute even more with again way less stress.
What is 'sounds strange' in this context? Can it be quantified, so that engineering might target this?
Audionaut
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Bonjour agnostic1er,
a very small loudspeaker that is supposed to transmit the entire spectrum is, as you can see here, always a very big compromise in terms of bass and level.
But an honorable attempt with the known limitations.
Since I myself don't like limitations in terms of level and low bass, I tuned this B&C 8-inch coaxial driver to 65 Hz bass reflex and gave it an 18-inch active subwoofer, which you don't notice visually as part of the shelf for the components.
This allows club volume and is a slightly different approach to compact loudspeakers.
Without a subwoofer, they don't sound anemic, only the low bass is missing.
Difficult. I noticed it when listening to some smaller yet very low-reaching active monitors which seemingly employ a lot of boost below 60Hz to get a 4" or 5" to reach 30 Hz or even lower. Some in a closed box, some in reflex with a tuning frequency similar to the aGnome which is much lower than what a standard calculation would suggest.
My guess would be it has to do with compression and frequency bands in which the system is running out of power or excursion reserves. Usually you have a band in which any compact system runs into compression issues first. Typically 100...180Hz for such a concept which is the first or second harmonic for impactful bass notes. If a lot of boost one octave lower is employed, the lower notes eat up the excursion and power reserves forcing the harmonics into compression, and that might describe the issue which I noticed. It is difficult to measure as we are talking about a mixture of frequencies, pretty dependent on the music material, in a dynamic situation.
That is the main reason why I shy away from super low-reaching compact designs as well as putting bass drivers in a sealed enclosure of a fraction the volume they are meant for (which always results in resonance frequency being to high). And why I would always prefer a ´natural´ tuning with only moderate boost.
Modern compact active concepts such as mobile bluetooth speakers avoid this by rigorously applying dynamic high-pass filtering so the ´kick´ 100-180Hz stays free from compression at higher SPL. Not really doable in a passive concept and requiring an awful lot of tuning in a DSP unit.
There must not be a suggestion. The Thiele/Small model lets us calculate what comes out given some parameters of driver and its 'alignment', as they put it. But there's excaly no reason to stick to e/g a "Butterworth" type filter.
The aGnome (on topic ;-) has a problem: tuning still above the regular, level wise peak demand for low frequency extension, which is ~40Hz, and no electronic limiter.
Not the least, that very 40Hz might be missing anyway because of the Fletcher/Munson curve. Even if it is produced, its relative level is kept, in lack of equalizer, well below even the overtones, let alone distortion components chime in rather quickly, again masking the 40Hz' presence. It is reproduced, sarcastically speaking, no offense, only to produce that distortion as some kind of an interesting drama down below.
Yep, for one, I still don't get the notion of someting 'natural' with a technical device. Second, that signal manipulation makes me shiver. It may work, but that is not what fidelity in reproduction should be. Reason is, that it is not flexible. It may be "good enough" for some type of musical entertainment, full respect from my side. It may fall apart with some other music. The use is narrowed down, and so interferes with culture and art. I think of this to be negative, destructive even for no better, pulling people into a lazy corner.
The aGnome doesn't do that. So, where it is positioned?
Btw on the technicalities I've got a few questions.
Why is the tuning not lowered down to 40Hz? Are the passive radiators too heavy already?
Why is the tweeter crossed over that high, and in case of a technical need, why not a 1" Vifa dome, that I used down to 1kHz successfully, given the limited output dictated by the bass? Price for these little wonders is around 25/pc for end users.
I agree that the standard calculation is not a matter of the Butterworth characteristics which is rather unimportant in a reflex design. It is the calculation of the resulting resonance frequency in the enclosure w/o port or radiator. Making the enclosure smaller and smaller than suggested (1/4th of the liters in this case) you push up the resonance and reach a situation in which no reasonably low reflex tuning is possible.
It should be possible to make them heavier but this might result in even less deep bass level, and many radiators become audibly ´wobbly´ when overweighted. The active driver itself and the air inside the enclosure are the limits here. If you tune the PM lower without adjusting volume and driver, you end up with the radiator producing very little SPL effectively in its resonance frequency band plus kicking the driver to enormous excursion in the region between the radiator´s maximum output and the tuning of the driver. It is usually a bad compromise.
If you want to put the reflex tuning even lower than 47Hz effectively, you need a different driver or much much more of enclosure volume. But: which driver allows a reasonable reflex of <45Hz tuning in 3.7l delivering flat response and keeping excursion acceptable over all the bands? I do not know a single one.
´Natural´ was meaning solely the bass from the given driver+enclosure w/o heavy EQ or boost.
Speakers of such volume always pose a compromise. There is no ´fidelity´ in terms of perfect bass impulses and max SPL w/o noticeable compression or other side effects. Every reasonably sized home speaker will have its weak frequency bands bringing either high-pass filtering, compression, impulse response or distortion to an audible level at medium-high SPL.
I have collected a personal listening test playlist of roughly 1,000 tracks solely for bass testing over the years. Give me a compact home speaker and one or two hours to find out which track will make it compress, limit, boom, distort, puke, grasp air or cut off lower bands. The last (and most compact ever) speaker to pass this test was equipped with a CB 12" dedicated subwoofer in roughly 32l net, pumping 500Watt RMS into the bass driver alone.
Everything below is a compromise and not suitable for each and every imaginable track containing bass. There are better concepts and less ideal ones. In recent years the knowledge on DSP and how to manage limited resources has made astonishing leaps. I would say that well-engineered active DSP speakers offering 1.5 or 2l per bass driver will surpass passive ones of the same size in terms of how the bass sounds and how many tracks will be reproduced on a satisfying level. I recommend to listen to Klipsch Detroit to get an idea.
OP
agnostic1er
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In fact it's the contrary; I would have chose a higher Fb in order to gain middle bass level; tuning to i.e. the 30Hz region would have exceed x-mech of the passive radiators and limit the bass level. What is the interest of searching low-bass with such a concept?
In France, a Vifa dome is more expansive than this Monacor and the reason of its choice is partly given in my first post. Fx around 2.3kHz is clever assuming the mid-woofer is fully able to go this frequency while limiting costs.
It's funny to see that some people give their opinion on this speaker explaining that Vb is too low, that the mid-woofer is too small, that the tweeter coulfd be another and on... without staying connected to the initial concept.
