For sealed a driver wit qts between 0.4 and 0.7 works the best. Not a low qts driver. Thise are more fit for reflex or horn loading. And most want the qtc of the box around 0.707. If you want the box to fit your enclosure find a high qts driver with a vas arround 54l and you’re close to the Qtc of 0,707
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ok I found two speakers that may work actually:
1. Visaton BG20
https://docs.rs-online.com/d128/0900766b8112b849.pdf
The specs sheet calls for 50lt BR using their BR 15.34 tube cut to 7cm length which should result a Fb of 42Hz
2. Monacor SP-200X
It is suitable for both sealed or BR
On a sealed cabinet of 57lt you get F3=68Hz
I think this is as good as it gets on my cabinets
Moreover, both speakers seem to be a bit shy on the high end which would probably require the addition of a super tweeter, maybe a ribbon with a high pass filter around 7kHz, give or take
Any thoughts?
1. Visaton BG20
https://docs.rs-online.com/d128/0900766b8112b849.pdf
The specs sheet calls for 50lt BR using their BR 15.34 tube cut to 7cm length which should result a Fb of 42Hz
2. Monacor SP-200X
It is suitable for both sealed or BR
On a sealed cabinet of 57lt you get F3=68Hz
I think this is as good as it gets on my cabinets
Moreover, both speakers seem to be a bit shy on the high end which would probably require the addition of a super tweeter, maybe a ribbon with a high pass filter around 7kHz, give or take
Any thoughts?
Well, back-calculating it from the provided gives roughly 19.5g. However, Mms is not especially relevant for multicone or mechanically decoupled wideband drive units, since only a fraction of that will in fact be resonating across much of the BW. Recall that wideband drive units do not operate as pistons but resonant structures. That's how they work.
Largely irrelevant for wideband drive units for the reasons mentioned above (and of questionable relevance for other types too). As largely resonant devices most require stiffer suspension to actually function, especially the short-throw high[er] sensitivity types.
If you want a sealed box rather than vented, stick with the higher Qt driver varieties unless Fs is very low by current standards. Crossing high is problematic with the polars, but many are happy so YMMV on that front. The BG20 and SPX200 are both quite cheap drivers so relatively inexpensive to experiment with.
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Madisound has some recommendations for ported cabinets:
Seas Prestige FA22RCZ (H1597-08) 8" Fullrange
for example 2.0 cf with 3" x 3" port for an F3 of 44Hz
2 cf = 56 lt
do they actually work?
does it matter where you place the port (height on the baffle)?
Seas Prestige FA22RCZ (H1597-08) 8" Fullrange
for example 2.0 cf with 3" x 3" port for an F3 of 44Hz
2 cf = 56 lt
do they actually work?
does it matter where you place the port (height on the baffle)?
I tried to reproduce the example given at Seas documentation
http://www.seas.no/images/stories/prestige/pdfdatasheet/fa22rcz_appnote.pdf
the blue line is a 46lt sealed cabinet with Q=0.707 and the green line is for a 74lt BR cabinet with QB3 response
The default port given by the software is 10cm diameter / 20 cm length but if I change to 6.8 cm diameter the length becomes 7.4 cm which is more consistent with a 3" x 3" port
http://www.seas.no/images/stories/prestige/pdfdatasheet/fa22rcz_appnote.pdf
the blue line is a 46lt sealed cabinet with Q=0.707 and the green line is for a 74lt BR cabinet with QB3 response
The default port given by the software is 10cm diameter / 20 cm length but if I change to 6.8 cm diameter the length becomes 7.4 cm which is more consistent with a 3" x 3" port
Attachments
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Thank you for your help. I am trying to understand so: should we say that Mms is important to be low in mid-low drivers? and for what sizes?
I guess beter way to achieve a high quality speaker is to make 2 or 3 way system. And it is dificult to achieve equal quality with just one full range all over the spectrum especialy for low end. Loking for Initialy for sealed small volume enclosure with large driver did not fing yet but also starting looking for vented way..
There is no fixed size as such. The point is that moving coil drive units are not all designed the same way, or for the same things. Wideband / fullrange drive units produce most of their output via resonance, and mechanically decouple portions of the cone as frequency rises, thus the actual moving mass varies significantly with frequency; in the HF it may only be a fraction of the rated Mms figure.
Multiway and single-driver design are basically different animals; both approaches have their own balance of merits and drawbacks, and there are good (and bad) examples of each general type.
The drive units I mentioned above were in reference to a vented 54 litre volume, so you may want to have another look at some of those.
Multiway and single-driver design are basically different animals; both approaches have their own balance of merits and drawbacks, and there are good (and bad) examples of each general type.
The drive units I mentioned above were in reference to a vented 54 litre volume, so you may want to have another look at some of those.
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could you please have a look at post #28 regarding the Seas driver? Does this look right to you?
I could extend the cabinet in order to increase its volume to ~75-80 lt
What about the port and its position on the baffle?
A few conceptual questions from a student!
Dear Stalwarts & Enthusiasts,
I couldn't find anything on the internet yet (or probably i missed recognising it on Martin King's wonderful site) to resolve a few conceptual questions on QW pipe design.
* When a driver is mounted in a QW pipe (or an open-ended terminated line of any geometry), the system resonance goes lower than the driver Fs (unlike in any other enclosure). On basis of this:
1. Is it safe to assume that the effective Mms that the driver's motor "sees" is greater than that as measured in free air and mentioned in the driver datasheet?
2. If yes, would the higher Mms also lower the high frequency extension as well as the sensitivity of a wide-band driver?
3. Does it have any indication that the column of air through the line/pipe acts as a constant load against the driver cone effectively helping control its excursion? Is this air column load effective only around the 1/4 wavelength tuning frequency, or consistent throughout the whole frequency band?
4. On basis of 3. above, for a given 8" driver, let us assume two boxes - a 54 litre simple closed box and a Tapered QW pipe with the same internal volume, i.e. 54 litres (with 1/4 wavelength tuning at approx. 45 hz.) - * Would the driver gain any advantage in the QW pipe (over the simple closed box) as far as its excursion-limited power handling in the lowermost operating frequency band is concerned (i.e. 100 hz and below)?
These questions have remained unresolved in my mind for a long time. I would be greatly thankful if anybody can shed some light on this.
Thanks in advance! 🙏
Sujat
Dear Stalwarts & Enthusiasts,
I couldn't find anything on the internet yet (or probably i missed recognising it on Martin King's wonderful site) to resolve a few conceptual questions on QW pipe design.
* When a driver is mounted in a QW pipe (or an open-ended terminated line of any geometry), the system resonance goes lower than the driver Fs (unlike in any other enclosure). On basis of this:
1. Is it safe to assume that the effective Mms that the driver's motor "sees" is greater than that as measured in free air and mentioned in the driver datasheet?
2. If yes, would the higher Mms also lower the high frequency extension as well as the sensitivity of a wide-band driver?
3. Does it have any indication that the column of air through the line/pipe acts as a constant load against the driver cone effectively helping control its excursion? Is this air column load effective only around the 1/4 wavelength tuning frequency, or consistent throughout the whole frequency band?
4. On basis of 3. above, for a given 8" driver, let us assume two boxes - a 54 litre simple closed box and a Tapered QW pipe with the same internal volume, i.e. 54 litres (with 1/4 wavelength tuning at approx. 45 hz.) - * Would the driver gain any advantage in the QW pipe (over the simple closed box) as far as its excursion-limited power handling in the lowermost operating frequency band is concerned (i.e. 100 hz and below)?
These questions have remained unresolved in my mind for a long time. I would be greatly thankful if anybody can shed some light on this.
Thanks in advance! 🙏
Sujat
I am not the expert to answer but I just sharing my thoughts I want to say your questions are very important.
Without being an expert It seems simply logical to me as a yes for 1 and 2 because the mass can not be irrelevent for low frequancies to my anderstanding and for 3 would be for only the low frequancies because of the diference on the speed of wave... But is it so simple?
Without being an expert It seems simply logical to me as a yes for 1 and 2 because the mass can not be irrelevent for low frequancies to my anderstanding and for 3 would be for only the low frequancies because of the diference on the speed of wave... But is it so simple?
vha, just a point to note:
1. For a magnet (motor) with a given Bl, Xmax and sensitivity are inversely related. Greater the Xmax, lower the sensitivity for the same motor; unless the motor strength is increased correspondingly with increased Xmax.
2. For a driver with a given area (Sd) - larger the Vas, greater is the compliance of the suspension. Compliance is opposite of stiffness. That means, a larger Vas = lesser suspension stiffness, and vice versa.
I hope my input is relevant to the purpose of this thread.
Mimikos, the EBP (Fs/Qes) is only a vague guide; not a rule.
The target Qtc of the sealed system (driver & box combined) is what will govern the selection of required driver Qes & Qts. Also, the application, placement in the room, lowermost operating frequency band of the desired system will guide the desired system Qtc.
For an F(-3) 40 hz and below, you might want to aim for a Qtc lower than 0.7, where you get clean impulse response as well as the "lift" in the low frequencies due to room gain.
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I understand this is a good one.. does anyone have experienced those? supravox 215 bicone
215 Signature Bi-Cone 35W / 94,5dB / 8 Ohms - Supravox
215 Signature Bi-Cone 35W / 94,5dB / 8 Ohms - Supravox
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