I'm getting 20Hz now with my Vifa 8" with plenty of dynamic swing for the volumes I listen to, both for music and movies. There's absolutely no reason why I wouldn't be able to accomplish the same with the ESS 10" woofer, even more so actually.
My little Fostex does just fine keeping up (crossed around 500Hz). Again, there should be no reason why the larger 10.2 shouldn't be able to do the same or better.
My little Fostex does just fine keeping up (crossed around 500Hz). Again, there should be no reason why the larger 10.2 shouldn't be able to do the same or better.
chops - exactly which 8" Vifa driver / enclosure design is giving you in-room 20Hz?
agreed that if one's room size / SPL requirements are modest, deep perceived bass is easier to achieve
yes, the 10.2 should be able to do well enough, and if you already have more than enough drivers with which to experiment, then recommendations for using smaller wide-band units in "FAST" type systems for their definite advantages are likely to be wasted
agreed that if one's room size / SPL requirements are modest, deep perceived bass is easier to achieve
yes, the 10.2 should be able to do well enough, and if you already have more than enough drivers with which to experiment, then recommendations for using smaller wide-band units in "FAST" type systems for their definite advantages are likely to be wasted
I've already posted about the Vifa on the first page. It's the P21WO-20. The Fs is 28Hz which is also the tuning freq of the 2.34 cf enclosure. In my room, they're easily reaching down to 20Hz if not darn near close to it.
As for the 10.2, I'll just be using one per side, likewise with the ESS 10" woofer as I'm pretty sure that's the one I'll be going with. It's supposed to be a very good, "fast" driver.
That's a very smooth looking driver, a nice candidate for a traditional 2-way. You don't see many woofers this size that can be run without a low-pass filter, like an old Dynaco A25. With your tuning, WinISD predicts an F10 of ~24Hz. Not too shabby.
jeff
I've been thinking a lot about this today while at work and at my brother's place after work...
Dave... You say I would need a woofer between 90-93 dB efficient. How about 94 dB? Is that too much or is that still do-able? The reason I ask is because of what I have to say below
Jeff... These Vifa/Scanspeak 8" drivers are nice drivers. They are extremely similar to the ones used in a several of Vandersteen Audio's speakers, if not the same.
Plus, I've been using these drivers for at least 10 years now, and have always been pleased and surprised at their performance. And as you have just discovered, they are very capable drivers, able to reach way down low. And F10 of 24Hz means that with typical room gain, I'm getting usable output down to 20Hz if not below.
Because of the reasons above, I think I am going to forgo the ESS driver and stick with these little Vifa/Scanspeak P21WO20 drivers, except running two per side which will give me roughly 94 dB efficiency (they're rated at 91 dB each).
I know how these drivers sound and I know what they are capable of. Having them side mounted will keep the front baffle thin and leave plenty of room for the type of port that I want to use.
Or something better.
XO point is determined my the driver responses and the width of the baffle (ie baffle step point). A rule of thumb starting point is root(2) times to 1 times the BS -3dB
The whole point is to use up the A10s
dave
chops - just to confuse things further - re your question of sealed vs vented - I've always preferred the sound of any Alpairs I've heard in various vented configurations, other than "standard" BR
of those that I've enjoyed, the MLTL or folded labyrinth for smaller sizes such as 70mm an under, are the easiest builds
of those that I've enjoyed, the MLTL or folded labyrinth for smaller sizes such as 70mm an under, are the easiest builds
If you have a speaker that is flat in a 2 pi environment (ie how they are measured) there will be a fall-off of up to 6 dB in the bass as the sound transitions from 2pi to 4pi steriradian radiation. Room & placement mean you rarely get the full theoretical 6 dB.
There are a numevr of ways to deal with bafflestep, the method we are interested here is where the XO is "at" the bafflestep, and the woofers are more sensitive than the mid-tweeter. Read the following and then the next article.
Baffle Diffraction Step
dave
I don't think I ever mentioned anything about sealed vs ported, especially concerning the Alpair. Considering what baffle width I decide on and what the baffle step will be (200 to 400 Hz), I would assume a vented enclosure for the 10.2 would be a moot point. I figured it would be sealed with some way of reducing or eliminating reflections in the enclosure. I actually prefer the clear natural sound of an OB honestly, but that would complicate things more for this design and I really don't want to go in that direction for this particular project.
As for the woofer section, it's apparently still up in the air concerning which drivers to go with. According to Dave, the combined output of the Vifa/Scanspeak 8" woofers @ 94 dB is too much. So I'm guessing I have to find drivers in the 88 - 90 dB range, so when combined will be between 91 - 93 dB. In the end, I want this system to be full range and well balanced, without the need of a subwoofer.
The only thing is, finding drivers in that efficiency range that has a good low Fs and smooth clean behavior up to and/or past 1 kHz. Of course, I won't be running them anywhere near that high, but I want to be sure no nasties get into the operating range that I'll have them working in.
I think my main thing is understanding and figuring out baffle step and how to cope with it. I have a basic understanding of it, but when I have abbreviations littered everywhere in posts that I don't know, it just confuses things more than helps. Plus, actual explanations would be a major MAJOR help. Just a thought... Hint...
Thank you, sir! I'm on my break at the moment, but I'll definitely read that link from beginning to end.
I don't want answers or suggestions just thrown at me. I want to be able to learn and understand along the way and be able to figure this stuff out so I don't have to be just asking questions all the time. I'm sure you know what I mean. I want to be able to actually contribute information as well at some point. Hopefully sooner than later.
Right...
As I was essentially saying in that post, I figured it would be pointless to do a vented enclosure for the Alpair since it would be relieved of bass duty, as in only playing down to around 200 - 300 Hz.
If the driver is being crossed over that high, what would a vent be tuned to, and why? What would be the advantage(s)?
When plotting such a thing as a HP filter of 250 Hz and a tuning freq of 250 Hz in WinISD Pro, for any port size, it comes up with a negative port length.
Assuming a passive XO: If you go sealed and the box resonance is too close to the XO point, you will find it very difficult to make the XO work. If you do a BR, the impedance peaks and the FR high-pass roll off will be low enough that a textbook XO might work. Box resonance 2 octaves below the XO frequency works.
I know nothing about line-level XO's. Let Dave speak to that.
I do active XO's: Put the Alpair in a Q=1 sealed box and then do your active XO at 250 or whatever.
The possibilities are endless. Depends on your skill set and your wallet.
Bob
I know nothing about line-level XO's. Let Dave speak to that.
I do active XO's: Put the Alpair in a Q=1 sealed box and then do your active XO at 250 or whatever.
The possibilities are endless. Depends on your skill set and your wallet.
Bob
I am partial to midTLs (heavy damping towards the terminus), which do 2 things.... they tend to suck the back wave into oblivion and can be used to reduce the impedance hump at box resonance, this last very useful if you are trying to do a passive XO.
dave
I just want to say something about the Vifa/Fostex series network speakers that I've been listening to today while doing tons of reading before getting on with the current topic...
I have been listening to a large variety of music today, analog, digital, acoustic, synth, processed, studio, etc, etc. Everything that I run through these cobbled together speakers sound so much better than the NHT 2.9's and Polk RTi12's. It's just a cleaner, more dynamic and more detailed presentation of the music. Whether it be FLAC files that I purchased from HD Tracks, CD's that I've ripped to FLAC, vinyl that I've spun. Today I have discovered new details deep in the music that I never knew was there before. This includes details in the treble, midrange and bass. Tiny high pitch shimmers, little faint echo effects hidden in the midrange, new found bass extension and notes that I never heard before. These speakers are opening up a big clean window into the music that I thought I knew.
And speaking of a clean big window, the sound stage is big. It spans beyond the width of the speakers and back wall, and beyond the height of the speakers. With some music, it also gives a holographic, almost surround effect. The NHT's and Polk's could never pull any of this off, not even marginally. I'm sure all of this is due to the simple series network and full range driver for the most part. The bass? Maybe due to the Vifa driver being able to react a lot better than the ones in the NHT's and Polk's due to complex crossover networks, and finally being properly tuned to 28 Hz. Then again, I never used these speakers with the much better amp, cables and gear either. The amp has major grip and detail. I'm finally able to realize that with these speakers!
** One thing I do notice (and I'll touch on this later below), these speakers can sound thin and forward from time to time, more often than not. I'm sure this has to do with the efficiency mis-match of the drivers used (91 dB for the Vifa & 89 dB for the Fostex) and baffle step raring its ugly face into the mix. It sometimes sounds like a big suck-out smack dab in the middle of the midrange. It almost gives an out of phase sound. However, if the music is complex where there's a lot going on, and with ample bass material, you don't really notice it that much. But not all my music is like that. Most acoustic and non-synth music has various amounts of this thin, forward, out of phase sound to it. **
Okay, now on to the project at hand...
Since I really like what that old Vifa 8" woofer does in the speakers above, I'm going to use the same in the new speakers, of course the new Scanspeak version of it which is identical to the old Vifa, and I'm only going to use one, mounted on the front baffle.
Mounted above that will be the single Alpair 10.2. Spacing between the two I'm not too sure on yet, but probably closer together than further apart. I know crossover point has a lot to do with that as well. However, I am going to take Dave's advise and build a "high ratio aperiodic TL" for the 10.2 to help reduce the impedance spike and help zap the back wave.
I'm going to try and fight baffle diffraction and baffle step physically with the help of a nice wide baffle. Right now I'm shooting for a max of 16" wide. This will get the BS down around 285 Hz if I did my math right. To help even further with this, I'm either going to give the baffle a large radius on the edges OR I'm going to make a wide, curved baffle, kind of like the Sonus Faber Stradivari, but on a much smaller scale of course.
** I really like the concept and simplicity of the series crossover network. The less components the better, so I think I want to implement that into the new design. I think that with the higher 91 dB efficiency of the Scanspeak woofer and lower 87 dB efficiency of the Alpair driver, they should be a pretty good match together without having to pad down the Alpair like I am currently with the Fostex. Plus, having a crossover point at or below 300 Hz should also help. IF I still need a BSC, I would think it would be low enough to use a smaller value inductor with a low DCR to keep from having any negative effects on the overall performance. **
With regards to the high ratio TL for the Alpair, would it make any difference venting it on the front baffle or out the rear?
Is there any "preferably free" software out there to calculate the small TL, or any size TL for that matter?
Would those aperiodic "pucks" as I call them be just as effective as the TL mentioned above?
Does all of what I have said here seem to be on the right track finally?
I look forward to hearing what all of you have to say as to the project and my questions. I would like to think that I have learned some things today and that I somewhat understand a bit more of it.
Thanks a bunch in advance!
I have been listening to a large variety of music today, analog, digital, acoustic, synth, processed, studio, etc, etc. Everything that I run through these cobbled together speakers sound so much better than the NHT 2.9's and Polk RTi12's. It's just a cleaner, more dynamic and more detailed presentation of the music. Whether it be FLAC files that I purchased from HD Tracks, CD's that I've ripped to FLAC, vinyl that I've spun. Today I have discovered new details deep in the music that I never knew was there before. This includes details in the treble, midrange and bass. Tiny high pitch shimmers, little faint echo effects hidden in the midrange, new found bass extension and notes that I never heard before. These speakers are opening up a big clean window into the music that I thought I knew.
And speaking of a clean big window, the sound stage is big. It spans beyond the width of the speakers and back wall, and beyond the height of the speakers. With some music, it also gives a holographic, almost surround effect. The NHT's and Polk's could never pull any of this off, not even marginally. I'm sure all of this is due to the simple series network and full range driver for the most part. The bass? Maybe due to the Vifa driver being able to react a lot better than the ones in the NHT's and Polk's due to complex crossover networks, and finally being properly tuned to 28 Hz. Then again, I never used these speakers with the much better amp, cables and gear either. The amp has major grip and detail. I'm finally able to realize that with these speakers!
** One thing I do notice (and I'll touch on this later below), these speakers can sound thin and forward from time to time, more often than not. I'm sure this has to do with the efficiency mis-match of the drivers used (91 dB for the Vifa & 89 dB for the Fostex) and baffle step raring its ugly face into the mix. It sometimes sounds like a big suck-out smack dab in the middle of the midrange. It almost gives an out of phase sound. However, if the music is complex where there's a lot going on, and with ample bass material, you don't really notice it that much. But not all my music is like that. Most acoustic and non-synth music has various amounts of this thin, forward, out of phase sound to it. **
Okay, now on to the project at hand...
Since I really like what that old Vifa 8" woofer does in the speakers above, I'm going to use the same in the new speakers, of course the new Scanspeak version of it which is identical to the old Vifa, and I'm only going to use one, mounted on the front baffle.
Mounted above that will be the single Alpair 10.2. Spacing between the two I'm not too sure on yet, but probably closer together than further apart. I know crossover point has a lot to do with that as well. However, I am going to take Dave's advise and build a "high ratio aperiodic TL" for the 10.2 to help reduce the impedance spike and help zap the back wave.
I'm going to try and fight baffle diffraction and baffle step physically with the help of a nice wide baffle. Right now I'm shooting for a max of 16" wide. This will get the BS down around 285 Hz if I did my math right. To help even further with this, I'm either going to give the baffle a large radius on the edges OR I'm going to make a wide, curved baffle, kind of like the Sonus Faber Stradivari, but on a much smaller scale of course.
** I really like the concept and simplicity of the series crossover network. The less components the better, so I think I want to implement that into the new design. I think that with the higher 91 dB efficiency of the Scanspeak woofer and lower 87 dB efficiency of the Alpair driver, they should be a pretty good match together without having to pad down the Alpair like I am currently with the Fostex. Plus, having a crossover point at or below 300 Hz should also help. IF I still need a BSC, I would think it would be low enough to use a smaller value inductor with a low DCR to keep from having any negative effects on the overall performance. **
With regards to the high ratio TL for the Alpair, would it make any difference venting it on the front baffle or out the rear?
Is there any "preferably free" software out there to calculate the small TL, or any size TL for that matter?
Would those aperiodic "pucks" as I call them be just as effective as the TL mentioned above?
Does all of what I have said here seem to be on the right track finally?
I look forward to hearing what all of you have to say as to the project and my questions. I would like to think that I have learned some things today and that I somewhat understand a bit more of it.
Thanks a bunch in advance!
No, it's not you imagination. I simply don't want to deal with bi-amping. That's extra money, extra equipment, and extra clutter.
The reason I asked about front vs rear terminus was if there was any performance advantage to either.
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