Moderators Youthman Posted February 4, 2016 Moderators Share Posted February 4, 2016 Sure... I love the RB61 for that very reason. Great amount of quality bass from a bookshelf speaker. I was also VERY surprised that the RF42ii had bass. They couldn't compete with the RF7ii but they sound nice by themselves Quote Link to comment Share on other sites More sharing options...
BusaDude Posted February 5, 2016 Share Posted February 5, 2016 Doubling speakers does NOT double efficiency, for example. I didn't say that... I said it doubled the amount of air moved, which contributes to an increase in SPL of 3 dB. And since every 3 dB increase in SPL requires a doubling of power, the 2 driver setup would increase (not double) efficiency. And it would reduce the amount of power needed (by 1/2) to generate the same SPL. Quote Link to comment Share on other sites More sharing options...
Quiet_Hollow Posted February 5, 2016 Share Posted February 5, 2016 the 2 driver setup would increase (not double) efficiency. Efficiency is not affected by the number of drivers. Quote Link to comment Share on other sites More sharing options...
Paducah Home Theater Posted February 5, 2016 Share Posted February 5, 2016 When you decide what to purchase for a particular purpose, how do you decide what size drivers to purchase. Just to confuse you... Typically mo bigger mo better in terms of frequency response, but there's also dispersion to consider. Larger drivers start beaming up high, which may be a problem for a particular design. Case in point, actual example actually, if you want to cross over a woofer at 1,100 hz or so due to liking a particular tweeter, do you use an 18" driver? Take the speed of sound in inches per second (13,503) divided by the cone size (18) = 750 hz, which is the approximate frequency that the dispersion will start narrowing. So, 18's may not be the best choice. Now do the same thing with a 12. 1125 hz. That's more like it. All things considered, you may opt for a smaller driver in a situation like this. Quote Link to comment Share on other sites More sharing options...
Paducah Home Theater Posted February 5, 2016 Share Posted February 5, 2016 I didn't say that... I said it doubled the amount of air moved, which contributes to an increase in SPL of 3 dB. Typically if you both double the drivers AND double the power, the rule of thumb is to expect more like a 6 db gain. Quote Link to comment Share on other sites More sharing options...
Paducah Home Theater Posted February 5, 2016 Share Posted February 5, 2016 (edited) the 2 driver setup would increase (not double) efficiency.Efficiency is not affected by the number of drivers. Eh, I'd say you're both kind of right. Everything else being equal, meaning you're not hindered by crossover design and whatnot, if you double the amount of drivers you can typically expect a 3 db gain. If you only double your amplifier power with the original number of drivers you can expect 3 db. If you both double your power AND drivers, 6 db. Pretty basic audio rules that have been around forever. But yes, just because a particular speaker design uses twice the drivers as another that even uses the same drivers does not mean it's automatically more efficient. Edited February 5, 2016 by MetropolisLakeOutfitters 1 Quote Link to comment Share on other sites More sharing options...
Paducah Home Theater Posted February 5, 2016 Share Posted February 5, 2016 A very basic question here but one that I think would be immensely help to understand. One speaker has say 1 8" driver and a tweeter. Another has 2, 3 or 4 8" drivers and a tweeter. Why? When you decide what to purchase for a particular purpose, how do you decide what size drivers to purchase. An example say is the Klipsch RP series....you can get the 250, 260 or 280 series. How and why would you choose between them? Yes it's a newbie question. Thanks in advance for any information shared. Respectfully, RK Several possible reasons.... First... a single 8" driver has a surface area = pi x radius x radius = 3.14159 x 4 x 4 = 50.27 square inches Two 8" drivers have a surface area = pi x radius x radius = 3.14159 x 4 x 4 = 50.27 x 2 = 100.54 square inches Now you've immediately doubled the amount of air you're moving, which in part gives you an increase in efficiency. This increase, by adding another driver of the same size/specs, gives you another 3 decibels in sound level. So if one 8" driver gave you 90 dB with 1 watt at 1 meter... then two 8" drivers will give you 93 dB with 1 watt at 1 meter. Or the two 8" drivers will give you 90 dB with exactly half the power, in this case 1/2 a watt. And since the drivers aren't moving as far to create the same sound level, they should be more linear (accurate) and create less distortion. You're assuming that you're just hooking two drivers up with no regards to the crossover or what impedance you'll end up with, which isn't reality. Quote Link to comment Share on other sites More sharing options...
Quiet_Hollow Posted February 5, 2016 Share Posted February 5, 2016 Eh, I'd say you're both kind of right. Good, otherwise we can toss out Physics and power those big kick-@ss line arrays at rock concerts directly off an iPod. Quote Link to comment Share on other sites More sharing options...
BusaDude Posted February 5, 2016 Share Posted February 5, 2016 A very basic question here but one that I think would be immensely help to understand. One speaker has say 1 8" driver and a tweeter. Another has 2, 3 or 4 8" drivers and a tweeter. Why? When you decide what to purchase for a particular purpose, how do you decide what size drivers to purchase. An example say is the Klipsch RP series....you can get the 250, 260 or 280 series. How and why would you choose between them? Yes it's a newbie question. Thanks in advance for any information shared. Respectfully, RK Several possible reasons.... First... a single 8" driver has a surface area = pi x radius x radius = 3.14159 x 4 x 4 = 50.27 square inches Two 8" drivers have a surface area = pi x radius x radius = 3.14159 x 4 x 4 = 50.27 x 2 = 100.54 square inches Now you've immediately doubled the amount of air you're moving, which in part gives you an increase in efficiency. This increase, by adding another driver of the same size/specs, gives you another 3 decibels in sound level. So if one 8" driver gave you 90 dB with 1 watt at 1 meter... then two 8" drivers will give you 93 dB with 1 watt at 1 meter. Or the two 8" drivers will give you 90 dB with exactly half the power, in this case 1/2 a watt. And since the drivers aren't moving as far to create the same sound level, they should be more linear (accurate) and create less distortion. You're assuming that you're just hooking two drivers up with no regards to the crossover or what impedance you'll end up with, which isn't reality. Funny how you ignored the part where I said... "All of these variables would then come into play within the speaker, crossover and how the cabinet is tuned." Quote Link to comment Share on other sites More sharing options...
BusaDude Posted February 5, 2016 Share Posted February 5, 2016 the 2 driver setup would increase (not double) efficiency. Efficiency is not affected by the number of drivers. I'm simply saying... To answer the OP's question about why it could matter... If you had two equal size/volume cabinets, one with nothing more than a single, generic 8" driver, capable of 90 dB 1w/1m. And the other with two of those exact same 8" drivers... And you feed both of them 1 watt... then you will in fact get 3 dB more SPL out of the "speaker" that has the two drivers. 1 Quote Link to comment Share on other sites More sharing options...
Paducah Home Theater Posted February 5, 2016 Share Posted February 5, 2016 Eh, I'd say you're both kind of right.Good, otherwise we can toss out Physics and power those big kick-@ss line arrays at rock concerts directly off an iPod. So why is the sensitivity of an Overnight Sensation MTM kit 4-6 db more efficient than the otherwise identical MT kit, when the nominal impedance only changed by 2 ohms? Quote Link to comment Share on other sites More sharing options...
Paducah Home Theater Posted February 5, 2016 Share Posted February 5, 2016 The other thing that wasn't mentioned here is that multiple drivers usually means less distortion in direct firing designs. In the OP's question, a single 8" woofer playing at the same high SPL as a design with four of the same 8" woofers will typically have quite a bit more distortion than the latter, which would just be cruising along comparatively. Quote Link to comment Share on other sites More sharing options...
Quiet_Hollow Posted February 5, 2016 Share Posted February 5, 2016 So why is the sensitivity of an Overnight Sensation MTM kit 4-6 db more efficient than the otherwise identical MT kit, when the nominal impedance only changed by 2 ohms? Because the word efficiency is being used interchangeably with the word sensitivity in context, whereas efficiency really hasn't changed at all. The confusion stems from the misuse of jargon. Sensitivity and Efficiency are measured using different parameters, and they don't mean the same thing even though they are both often times expressed in dB. One equation is based on voltage and SPL, and the other is based on total power, respectively. That's a really important difference. It would be more meaningful try to describe instead why a 2" semi-rigid diaphragm in a K55/K400 combination can produce significantly more SPL than the same diaphragm mounted free-air on a baffle, or even when compared to a 2" high performance dynamic driver. The book on that subject already exists. Reference: http://www.klipsch.com/education/speaker-sensitivity 1 Quote Link to comment Share on other sites More sharing options...
RoboKlipsch Posted February 5, 2016 Author Share Posted February 5, 2016 Thank you to everyone who has posted. I read through everybody's posts, clicked and read the links from Youthman (thank you). Very good stuff to read. Like so many things, designing a "great" speaker would appear to require incredible knowledge and experience combined with a willingness to experiment and use trial and error and feedback from users. The question was answered better than I could have expected...thank you all again. Quote Link to comment Share on other sites More sharing options...
etc6849 Posted February 5, 2016 Share Posted February 5, 2016 (edited) I would seriously make your room as dead as possible. Just buy some 4" Owens Corning panels and wrap them in burlap. I just made an awesome 8 foot x 4 foot x 1.5 foot bass trap made out of 4 pieces covered in clothe. Also do the sidewalls as best you can. You will never reach nirvana no matter how much you spend on gear until you master room acoustics and at a minimum have dual matching subs placed in ideal locations. PS: it isn't about freq response plots at all. What matters most is impulse/ETC and waterfall plots. There's a good thread on AVSforum on using REW. Edited February 5, 2016 by etc6849 Quote Link to comment Share on other sites More sharing options...
WMcD Posted February 6, 2016 Share Posted February 6, 2016 (edited) One matter is the width of the box. Klipsch and other make tall thin boxes and this changes the horizontal pattern. The Palladium for example, but there are others, earlier. So you may be forced to go with two small woofers (stacked) to keep a radiating area the same as one large woofer. There is also the beaming issue. One school of thought is that it is best if the beam of the woofer at crossover freq is about that of the treble unit. The use of the klipsch type treble horns lets that be about 90 degrees by 90 degrees and so you back figure the crossover freq to where the pattern of the woofer is about that too. I've noticed that many of the Klipsch designs use a woofer about the same dimensions as the treble horn. IIUC: Stacking two or more woofers will actually increase the horizontal pattern. So now you've got better bass but too much dispursion at the crossover freq with both woofers working. What to do? In some Klipsch speakers with two stacked woofers there is trick implemented by the crossover circuit. It allows both bass drivers to "sound" at low freqs for good efficiency down there. Then as we go higher, the bottom one is turned off -- so that only the top one near the treble horn is working. In that way, the top woofer is actually acting like a midrange. And its dispursion can match the treble horn. - - - - The headphone analysis (small woofer but good bass) is a bit misleading. In can type phones and of course in the ear, there is a pressure seal and so we're not concerned with size of driver very much and since it is at your ear, we're not concerned about efficiency. - - - - It is possible to use a small woofer to make deep bass. But you have to understand that all direct radiators don't have good efficiency at low freqs acoustically (related to area of the diaphragm and the related acoustic resistance curve). This poor bass efficiency is solved by adding mass to the moving system to dumb down the treble. This mass loading is a type of built in equalization. If you have a bass system with poor acoustic loading because of small radiator, you can equalize it by cutting treble, but the system is inefficient. WMcD Edited February 9, 2016 by WMcD 2 Quote Link to comment Share on other sites More sharing options...
RoboKlipsch Posted February 9, 2016 Author Share Posted February 9, 2016 I haven't been around long, why does Klipsch have a RF7ii speaker line separate from the Reference Premiere? It seems universal that people here like the RF7s a lot more than the RP line...why so few items in the RF7 lineup? Is it a legacy of the past they keep because they are popular? Quote Link to comment Share on other sites More sharing options...
dmb12679 Posted February 9, 2016 Share Posted February 9, 2016 Klipsch updated everything from the ii to the reference premier line except the rf7ii. I'm not sure why either. Maybe they had a surplus of inventory that they figured if they put out a new 7, the old would be selling for less. Or maybe the improvements to the 7's were not enough to warrant an updated model at this point. I still want to see a 3 woofer rf7. Someone on here has a photoshopped pic of one. It would be awesome. Quote Link to comment Share on other sites More sharing options...
derrickdj1 Posted February 9, 2016 Share Posted February 9, 2016 (edited) Three woofers seems like a waste if you heard the RF 7 II's. No more bass is needed in that speaker. IMHO, the reason the RF 7 II is still around is because it is a darn good speaker. Edited February 10, 2016 by derrickdj1 Quote Link to comment Share on other sites More sharing options...
mattSER Posted February 10, 2016 Share Posted February 10, 2016 (edited) I haven't been around long, why does Klipsch have a RF7ii speaker line separate from the Reference Premiere? It seems universal that people here like the RF7s a lot more than the RP line...why so few items in the RF7 lineup? Is it a legacy of the past they keep because they are popular? It's kinda like this: 1st generation Reference flagship was the RF-7 2nd generation Reference flagship was still the RF-7 3rd generation Reference flagship was the RB-75 4th generation Reference flagship was the RF-83(and RF-63) 5th generation Reference flagship was the RF-7ii So for the sixth Reference generation(Premiere), they have simply not updated the flagship....yet. ...or they may just wait until RPii Edited February 10, 2016 by mattSER Quote Link to comment Share on other sites More sharing options...
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