Hi all,
I have just returned from a business trip to Japan, and I have brought a pair of Alpair 7P drivers with me. Now the question: what to do with them? Using them full-range is not feasible in my situation, because they would not be able to produce sufficient volume in the lows without being destroyed. So they need a woofer.
The 7P/12PW combination is very interesting, but it is already being discussed here. Therefore, I would like to explore other alternatives in this thread.
My first thoughts were going towards mating the 7P with a woofer with a sensitivity in the range of 90 to 91 dB, and cross over around the baffle step frequency (perhaps with an acoustical LR2) which will be in the 200 to 300 Hz range depending on cabinet geometry. In this way, the baffle step is taken care of with only minimal padding down of the Alpair, and the overall system sensitivity would end up at a very reasonable value and provide ample output. The woofers I found thus far that seem to suit the bill are the Seas CA26RE4X and CA26RFX. I was also looking at the SB34NRXL75-8 from SB, although honestly, I find it a bit excessive. But I may be wrong on any of these points!
These are just my first thoughts, so subject to change. Any ideas are much appreciated! I hope this gets interesting...
I have just returned from a business trip to Japan, and I have brought a pair of Alpair 7P drivers with me. Now the question: what to do with them? Using them full-range is not feasible in my situation, because they would not be able to produce sufficient volume in the lows without being destroyed. So they need a woofer.
The 7P/12PW combination is very interesting, but it is already being discussed here. Therefore, I would like to explore other alternatives in this thread.
My first thoughts were going towards mating the 7P with a woofer with a sensitivity in the range of 90 to 91 dB, and cross over around the baffle step frequency (perhaps with an acoustical LR2) which will be in the 200 to 300 Hz range depending on cabinet geometry. In this way, the baffle step is taken care of with only minimal padding down of the Alpair, and the overall system sensitivity would end up at a very reasonable value and provide ample output. The woofers I found thus far that seem to suit the bill are the Seas CA26RE4X and CA26RFX. I was also looking at the SB34NRXL75-8 from SB, although honestly, I find it a bit excessive. But I may be wrong on any of these points!
These are just my first thoughts, so subject to change. Any ideas are much appreciated! I hope this gets interesting...
With the predominance of Cone + dome 2-ways there are lots of suitable woofers. Using them as a helper woofer removes the part of the spectrum where they likely have there greatest number of issues.
Choose a woofer(s) with an appropriate sensitivity (if you are going for a passive XO), XOing such that it deals with baffle step is a good idea. They need to go as low as you'd like andneed to fit into a box size you can live with. If woofers are placed close to the FR then with a low XO they can effectively co-incident. Good extenion by both drivers on the other side of the XO means that a simplier XO can often be used (we have mostly been experimenting with 1st order series)
The woofers we have successfully used to date are SDX7 & EL166 (both no longer available), Peerless 830870 & Silver Flute W14. Next up is the A12pw.
Passive XOs are harder to get right than a PLLXO (and hard to beat the price if you have the amps), we have also tried full active XOs but have yet to find one that didn't intrude in some way. The best was a battery powered opAmp buffered PLLXO, but it really needs a wall supply, when the battery ran out (far too quick) it made some awful noise. A FirstWatt B1 style buffered PLLXO is high on the list to try -- there is a whole thread on those some where.
I have a number of orpaned samples that did not work out for one reason or another.
dave
Choose a woofer(s) with an appropriate sensitivity (if you are going for a passive XO), XOing such that it deals with baffle step is a good idea. They need to go as low as you'd like andneed to fit into a box size you can live with. If woofers are placed close to the FR then with a low XO they can effectively co-incident. Good extenion by both drivers on the other side of the XO means that a simplier XO can often be used (we have mostly been experimenting with 1st order series)
The woofers we have successfully used to date are SDX7 & EL166 (both no longer available), Peerless 830870 & Silver Flute W14. Next up is the A12pw.
Passive XOs are harder to get right than a PLLXO (and hard to beat the price if you have the amps), we have also tried full active XOs but have yet to find one that didn't intrude in some way. The best was a battery powered opAmp buffered PLLXO, but it really needs a wall supply, when the battery ran out (far too quick) it made some awful noise. A FirstWatt B1 style buffered PLLXO is high on the list to try -- there is a whole thread on those some where.
I have a number of orpaned samples that did not work out for one reason or another.
dave
Hi Dave,
Thank you for your thoughts. I am currently exploring two approaches, which are very different from each other.
The first path would be to combine the 7P with a smaller woofer with an extended response like the ones you just suggested, and the Alpair 12PW is #1 on my shortlist, but the ones you suggested should be added as well. They are certainly easier to obtain over here, and a lot cheaper. There is a lot of freedom in filter design due to the extended response of both the woofer and the A7P. First order series is indeed what I am thinking of. I would like to have a passive XO, because I like the simplicity of the straightforward source-amp-speaker setup.
The second path would be to use a beefier woofer, and filter second-order filter around 300 Hz, so the A7P's are leading an easy life, even if they are asked to produce a lot of racket. Filter design would leave a little less freedom, but overall system sensitivity would be higher and the system would be more suitable for a somewhat large room. For this approach, i would prefer a single woofer with a sensitivity of around 90 dB. For this, I would also like to get suggestions beyond the ones that I have already found. I have searched a lot of woofers, but I am convinced that I have overlooked just as many suitable options.
Thank you for your thoughts. I am currently exploring two approaches, which are very different from each other.
The first path would be to combine the 7P with a smaller woofer with an extended response like the ones you just suggested, and the Alpair 12PW is #1 on my shortlist, but the ones you suggested should be added as well. They are certainly easier to obtain over here, and a lot cheaper. There is a lot of freedom in filter design due to the extended response of both the woofer and the A7P. First order series is indeed what I am thinking of. I would like to have a passive XO, because I like the simplicity of the straightforward source-amp-speaker setup.
The second path would be to use a beefier woofer, and filter second-order filter around 300 Hz, so the A7P's are leading an easy life, even if they are asked to produce a lot of racket. Filter design would leave a little less freedom, but overall system sensitivity would be higher and the system would be more suitable for a somewhat large room. For this approach, i would prefer a single woofer with a sensitivity of around 90 dB. For this, I would also like to get suggestions beyond the ones that I have already found. I have searched a lot of woofers, but I am convinced that I have overlooked just as many suitable options.
I'm not sure if this is the appropriate forum for this topic/thread, you're looking to discuss details on drivers other than MA. That said, the choice seems pretty clear to me..SBA 8, 10 or 12 would be my choice. The further away from walls you plan to be, opt for the bigger driver. The 8 comes in paper or alloy I believe.
@timboz: I think this is the appropriate place, because I am after application suggestions for the A7P. That speaker is a given, so it doesn't need to be discussed. There are more SB woofers that come in alloy or paper, but I think it would be a good idea to stick to the paper ones. They make some interesting speakers!
@rock12: never heard of that speaker. It seems to be intended for open baffle use, judging from the Qts of 0.6.
@rock12: never heard of that speaker. It seems to be intended for open baffle use, judging from the Qts of 0.6.
@planet 10: I have looked a bit closer to the Peerless 830870, and it looks like it is capable of about the same output as the A7P, having only a tad more surface area, but 25% less Xmax. One solution would be to use a lot of them, but they still wouldn't go deep. The Silver Flute has a bit more to offer, but it doesn't come close to the Alpair 12PW when it comes to output capability and response extension. I have also looked at the SB Acoustics Satori midwoofers, but they must also bow for the A12PW. Since I have a reasonably large room to fill, the Alpair 12PW looks like the clear winner in usage scenario 1 (post 3). Too bad its availability is so poor in my country.
For scenario 2, the mentioned SEAS woofers seem to fit very well, although I must admit I have one thing against them: they're shiny! Call me crazy, but I hate it. So I still look for similar performance with a non-shiny cone surface. So any ideas are welcome.
So it seems that I simply need to find the "perfect" woofer for scenario 2, and then make a decision on which path to take...
For scenario 2, the mentioned SEAS woofers seem to fit very well, although I must admit I have one thing against them: they're shiny! Call me crazy, but I hate it. So I still look for similar performance with a non-shiny cone surface. So any ideas are welcome.
So it seems that I simply need to find the "perfect" woofer for scenario 2, and then make a decision on which path to take...
We use 2 (in an ML-TL) or 4 (in an ML-V), push-push pairs. They go plenty low. And with near 10k ectension easy to XO.
Here the twin woofer application.
When we went to do the MTM, this was the 1st woofer we looked at. It needed 15 litre/driver to get the same extension as the SF W14 did in 5. The MTMs don't go as low as the ML-TLs.
We also have a larger woofT (ML-TL) for the W14. Looks like a fatter version of the woofT for thw uFonkenSET above.
dave
The fun with those designs was to use mid-bass drivers of approx the same size range as the full-rangers - and watch listeners' reactions
Do a total of 8 of the Peerless 83870 so a low or loud as, say a 15" JBL or 12" Tannoy Dual Monitor in a TL or BLH? - well, no - but do they "work" as a system with the full-rangers? - sorta quite well actually. There's something about the side mounted push/push configuration - which we've done a few times with a range of woofer makes and sizes.
Do a total of 8 of the Peerless 83870 so a low or loud as, say a 15" JBL or 12" Tannoy Dual Monitor in a TL or BLH? - well, no - but do they "work" as a system with the full-rangers? - sorta quite well actually. There's something about the side mounted push/push configuration - which we've done a few times with a range of woofer makes and sizes.
@ planet10 & chrisb: thanks for pointing out this interesting cabinet option. You guys haven't made it easier for me! Anyhow, evaluating options is part of the fun, and it is certainly the cheapest phase of the project. So I should thank you for helping me keep money in my pocket for another while as well ;-)
So instead of 2 options, it seems that I now have three:
1- Alpair 12PW in a conventional reflex enclosure, crossed over to the 7P with a series filter. Pros: both drivers likely to have matching sound character, looks of both drivers match (yes, this is important to me), response of both drivers allows some freedom in XO design, good bass extension. Cons: Alpair 12PW difficult and expensive to obtain for me.
2- Seas 26CA family woofer in a closed or reflex enclosure, with the A7P as a combined midrange/tweeter using a 2nd order acoustic slope around the baffle step freqency. Pros: higher output capability at low frequency, good efficiency, robust, good potential for being a great all-rounder. Cons: large, ugly woofer is visually no match for the A7P.
3- Multiple cute Peerless 830870 woofers driving a MLTL. Pros: extended response gives almost the same freedom in filter design as option 1, MLTL allows unusual (slender) cabinet shape, visual mismatch not much of an issue with side-firing woofers, bass extension below driver fs. Cons: I still need to figure that out.
If all drivers were put on a table in front of me, I would probably pick option 1. But now, I don't know yet. I must go do something else, but in the meantime, I welcome any input to further complicate the decision process...
So instead of 2 options, it seems that I now have three:
1- Alpair 12PW in a conventional reflex enclosure, crossed over to the 7P with a series filter. Pros: both drivers likely to have matching sound character, looks of both drivers match (yes, this is important to me), response of both drivers allows some freedom in XO design, good bass extension. Cons: Alpair 12PW difficult and expensive to obtain for me.
2- Seas 26CA family woofer in a closed or reflex enclosure, with the A7P as a combined midrange/tweeter using a 2nd order acoustic slope around the baffle step freqency. Pros: higher output capability at low frequency, good efficiency, robust, good potential for being a great all-rounder. Cons: large, ugly woofer is visually no match for the A7P.
3- Multiple cute Peerless 830870 woofers driving a MLTL. Pros: extended response gives almost the same freedom in filter design as option 1, MLTL allows unusual (slender) cabinet shape, visual mismatch not much of an issue with side-firing woofers, bass extension below driver fs. Cons: I still need to figure that out.
If all drivers were put on a table in front of me, I would probably pick option 1. But now, I don't know yet. I must go do something else, but in the meantime, I welcome any input to further complicate the decision process...
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If you can find a way to implement bi-amp this combo (how many of us don't have a spare amp or 6?) with either PLLXO or even with computer sound card / other software, your cost of XO components will plummet, and you gain so much more flexibility
We're currently working on an MTM with pair of 12PW and A7P in an dual TL enclosure - MLTL for the 12s, and small tapered rear terminus TL for the 7. This combination worked very well with the EL166, and a 3" FR driver by another maker. While both approaches have merits, passive XO parts can get costly, and there are some other shortcomings that active can work around.
We're currently working on an MTM with pair of 12PW and A7P in an dual TL enclosure - MLTL for the 12s, and small tapered rear terminus TL for the 7. This combination worked very well with the EL166, and a 3" FR driver by another maker. While both approaches have merits, passive XO parts can get costly, and there are some other shortcomings that active can work around.
Chris,
Looking forward to seeing the build & plans for this, also how it compares to the simple 2-way plans released for the 7P&12PW combo.
Timpert, not intending to sidetrack your thread so my vote is for the 7P+12PW combo and be one of the early adapters.
Regards,
Anton
Looking forward to seeing the build & plans for this, also how it compares to the simple 2-way plans released for the 7P&12PW combo.
Timpert, not intending to sidetrack your thread so my vote is for the 7P+12PW combo and be one of the early adapters.
Regards,
Anton
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Since the discussion hasn't been censored yet, I did a pair of FAST speakers using the A7M over the Audax HM210C0. The driver choice was at customer insistence and 8"ers are a bit larger than most FAST basses, but I was very much impressed with the Audax. Very clean and very low distortion. I crossed a 700Hz passive because again of customer request. I personally would cross active and a bit lower.
The down side of most Audax driver is that XXXXXX squared of frame.
Bob
The down side of most Audax driver is that XXXXXX squared of frame.
Bob
Anton- still wresting the CAD drawings into wood - funny how the complexity of the actual build seems to increment logarithmically with the number of drivers in separate compartments nested this tightly together. Certainly not simplified by the dimensions of frames on Mark's Alpair series.
I think I've said this before - once the math is done, it can me much easier to draw some enclosures than to build
And maybe I'm off-base, but as long as the subject doesn't veer off the topic of alternatives to use
with A7P (or other MA drivers), I think Mark would be cool with it
I think I've said this before - once the math is done, it can me much easier to draw some enclosures than to build
And maybe I'm off-base, but as long as the subject doesn't veer off the topic of alternatives to use
with A7P (or other MA drivers), I think Mark would be cool with it
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@a3cervo: Yes, i don't mind being a little adventurous, but so far I have difficulty obtaining the 12PW's at reasonable cost, and that basically kills it off.
Meanwhile, I have been playing with EDGE (baffle diffraction simulator), and I found that involving the baffle step in the crossover between woofer and A7P goes easier with a baffle that is too small to accommodate a 26 cm woofer. Going to a 22 cm woofer eases things up, just enough to become practical. That would be the SEAS CA22RNY (still ugly), or the Audax Bob mentioned (better looking), which has the right sensitivity for this purpose.
Meanwhile, I have been playing with EDGE (baffle diffraction simulator), and I found that involving the baffle step in the crossover between woofer and A7P goes easier with a baffle that is too small to accommodate a 26 cm woofer. Going to a 22 cm woofer eases things up, just enough to become practical. That would be the SEAS CA22RNY (still ugly), or the Audax Bob mentioned (better looking), which has the right sensitivity for this purpose.
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