Heya.
RCF recently released new high excursion drivers LN16S400 and LN19S400.
To me it looks they did right with the suspension what B&C didn't, but oh well 4" CCAW voice coil doesn't allow it to sit in our "sick top end" class. That is unfortunate.
Anyone planning on using these in their project? I wonder if one can push these into smaller volumes (150l for 19"). These need excursion to not burn...
RCF recently released new high excursion drivers LN16S400 and LN19S400.
To me it looks they did right with the suspension what B&C didn't, but oh well 4" CCAW voice coil doesn't allow it to sit in our "sick top end" class. That is unfortunate.
Anyone planning on using these in their project? I wonder if one can push these into smaller volumes (150l for 19"). These need excursion to not burn...
Missed that one. Cool!
I have less satisfactionary experience with CCAW wired speakers, but RCF knows how to do their stuff. The 4.5" version looks real good. B&C kinda "effed up" with their tight spiders. While RCF beasts lurked around 20-22mm of thermal limit inducing excursions, now possibly pushing it further, B&C is way down at 16-17mm one way. To get off that territory, we are talking about 12-14mm, and that's not all that exciting anymore. I have smoked few DS115 drivers due to the issue.
I have less satisfactionary experience with CCAW wired speakers, but RCF knows how to do their stuff. The 4.5" version looks real good. B&C kinda "effed up" with their tight spiders. While RCF beasts lurked around 20-22mm of thermal limit inducing excursions, now possibly pushing it further, B&C is way down at 16-17mm one way. To get off that territory, we are talking about 12-14mm, and that's not all that exciting anymore. I have smoked few DS115 drivers due to the issue.
All are interesting. Either for cinema purposes with low tuning, or for increasing SPL density. With these you can afford to tune them between 25-30Hz, cut em at 28-35Hz, let em work around their impedance peak efficiently, and have quite power dense compact solution. The port will only be there for impedance shaping, cooling and cone excursion settings, so it can be nearly half the size of conventionally sized port.
Small port, 100-150l internal box volume depending on the model and needs, and you have nice efficient compact beasts. Older models simply are not capable of that. I think this is a good path if SPL density and compactness is important for you.
You can feed em with 2500-3000Watt amp, because the power will not go there anyways.
Small port, 100-150l internal box volume depending on the model and needs, and you have nice efficient compact beasts. Older models simply are not capable of that. I think this is a good path if SPL density and compactness is important for you.
You can feed em with 2500-3000Watt amp, because the power will not go there anyways.
I have 21" woofers. For me it is obvious. Proper 21" sub cannot be "one man box" for loading onto a truck. I did it, and the compromise is exactly one hair too much of a compromise. It would need some more volume for the driver to be happy. At that point it's too big and heavy. These RCFs are light as F. The box can be smaller with smaller diameter drivew and low Qs. That makes it doable while maintaining cone displacement volume, for basically zero compromise on bass. I cannot see myself buying anything else compared to competition.
I am not saying it is wrong, but for this driver, excursion of 10mm above tuning frequency is not that desirable. The coil needs to fly and to cool down. Otherwise magic smoke could appear. I did it to my 21DS115s, although it only started to smell. The driver srsly can do it all, without the need of a port. The port doesn't add much efficiency anyways. 150l as I see in the input data is doable with such driver, but indeed, should in ballpark of fair minimum. Bigger volume might help with excursions too.
That´s a good question to ask.
There is no such specification, but historically and logically, there is best heat transfer from the coil to the air and pole piece when these swing around each other fully. Outside of that space, there might be less air flow or even pressure. Might...
Anyways, as the coil is 42mm long and the pole piece is 16mm high, it means that in order for the edge of the coil to travel around the pole piece, you need 13-14mm of swing for coil edges to cool down best on this speaker. Otherwise it might burn its edges sooner than "expected".
Undertuning solves this issue, and adds more positive consequences:
1) At the tuning frequency where there is least coil movement and therefore poorest cooling, there is not as much musicall content as there is let´s say at 35-40Hz. So less strain in the worst region for the speaker already.
2) Undertuning causes that in the spectrum of usable content, you have higher impedance. You are working more around the impedance peak compared to working more in the impedance valley of the port tuning, meaning that less power goes to the speaker. Less heat generated again.
I found it briliant for compact design SPL dense box. The caveat was that older drivers with Xmax around 10-12mm could not do that yet. RCF with nearly 20mm CAN.
There is no such specification, but historically and logically, there is best heat transfer from the coil to the air and pole piece when these swing around each other fully. Outside of that space, there might be less air flow or even pressure. Might...
Anyways, as the coil is 42mm long and the pole piece is 16mm high, it means that in order for the edge of the coil to travel around the pole piece, you need 13-14mm of swing for coil edges to cool down best on this speaker. Otherwise it might burn its edges sooner than "expected".
Undertuning solves this issue, and adds more positive consequences:
1) At the tuning frequency where there is least coil movement and therefore poorest cooling, there is not as much musicall content as there is let´s say at 35-40Hz. So less strain in the worst region for the speaker already.
2) Undertuning causes that in the spectrum of usable content, you have higher impedance. You are working more around the impedance peak compared to working more in the impedance valley of the port tuning, meaning that less power goes to the speaker. Less heat generated again.
I found it briliant for compact design SPL dense box. The caveat was that older drivers with Xmax around 10-12mm could not do that yet. RCF with nearly 20mm CAN.
I wonder how feasible it would be to do a breakdown-style box that is reassembled on site using something like a flanged construction. Just like pipe flanges, but obviously with wood instead. If it worked OK, you could have 2 or even 3 parts that would be smaller and lighter, and then finally bolted together in position.
I did entertain such idea in past, but the disadvantages make it less than appealing. I can imagine something like EAW BH760 style in a "pull design" where the last segmen of the horn would make a shell of the box, into which the throat side would be pushed when inactive.
I might think about it again, but you are not really saving weight, not creating more SPL density on playing box, you might lose pieces, you slow down loading and unliading, xou might look like a fool at times. Just not worth it.
Also Two 16"s will do more damage than one 21", and will be more power dense. So that's that. I would do even car audio 8"s if I didn't have personal issues with driving speakers in series.
I might think about it again, but you are not really saving weight, not creating more SPL density on playing box, you might lose pieces, you slow down loading and unliading, xou might look like a fool at times. Just not worth it.
Also Two 16"s will do more damage than one 21", and will be more power dense. So that's that. I would do even car audio 8"s if I didn't have personal issues with driving speakers in series.
I don't know how you guys, but I really appreciate 13" (B&C), 16" and 19" (RCF). As it does not come alone, with other adancements, clearly I can now use 19" driver with the displacement of 21", and such space reduction does make difference. 12"s are great for tops, but if you cross them lower to keep the upper bass, their excursion causes more doppler distortion, while 15"s come with much more significant directivity issues and cone flex. And if you are sick perfectionist, well! 😉
Finally someone who understands why I dont like Alu wire based VCs for high power applications. Even if they weren't susceptible to higher temp coefficient induced parameter change and temp cycle fatigue, the junction where VC winding and lead wire comes together is always going to be compromised.
Its an engineering challenge to reliably solder Alu to Cu. Most companies crimp this termination point, since its alot quicker and cheaper than welding. Those who have experience with some older Alu wire VC ScanSpeak drivers know what I'm talking about. The failure point is almost always the lead wire/VC winding junction and its usually covered with a tough adhesive to protect it from the elements. You'll end up damaging the driver trying to repair it and replacements may not be available anymore.
Loading LF drivers with Alu VC windings at their min impedance / min excursion and max current range (close to Fb and/or just above the second impedance peak) produces alot of heat. The overhanging VC windings sitting outside of the magnet gap can't shed their heat as well. Even if the driver doesn't fail, it unevenly heats and fatigue ages the VC. How fatigued it already is becomes a guessing game, as the heat treat isn't visible under the enamel coating unless its discolored, in which case the damage is already done.
The more VC layers and overhang, the worse the problem becomes. The higher temp coefficient further adds insult to injury. Don't even think of running drivers or similar cabs wired in series because power sharing will get even more unpredictable.
What some don't understand is driver loading will vary even by physical location in a sub stack when drivers or enclosures are wired in series. The enclosures running closer to the floor will sink more power than those sitting on top thanks to acoustical loading.
These are all reasons why I won't use LF or midbass drivers with Alu based VC windings for high power PA. Cu wire VCs are the only way to go for these purposes, despite the weight penalty. Its safe to say the only way to improve reliability with Alu windings is derating power by 1/3 to 1/2 published max power spec. Whats the point of having all that extra VC overhang when you can't reliably apply the necessary amount of power long term to utilize it?
I wasn't aware there were so many pro LF drivers out there with Alu wire VCs. That's planned obsolescence IMO and defeats the purpose of having other design compromises in place which hurt SQ while they're supposed to increase reliability (ie. low compliance double spiders, stiffer cones and heavier, higher density VC adhesives). These all hurt sensitivity and in return require more input for given SPL. Drivers used in FLHs with small sealed back chambers and no outside airflow to VC windings suffer the most in this scenario, including other types using smaller chambers in their designs. I won't use anything other than Cu wire based VCs in FLHs because of these reasons.
If you choose to run drivers with Alu VC windings, the only way to increase power handling reliably in sustained higher output operation is monitoring drive with an appropriate DSP using algorithms which carefully limit or reduce input power without excessively compromising SQ and max output in sustained operating conditions, especially in hot humid climates.
I also won't limit myself to proprietary driver dimensions that don't allow for easy last minute substitutions in the field, let alone the higher prices they command up front from the extra engineering they require to design and build. You can't just drop in a similar performing driver in a pinch like you can with a 15" or 18". That flexibility just doesn't exist with weird, non-standard sized drivers.
I agree that most subs with 21"+ drivers require two man handling. If these are designed to be lighter than average weight, SQ will suffer. Low mass, light weight cabs don't sound as good, even when stacked and weighed down.
You can fix some of these problems with concrete blocks, bags of lead shot etc, but thats rather impractical IMO, especially when required to run more subs for higher output and/or lower cutoffs. That really defeats the whole purpose of going with such high tech specialty drivers. EQing lower than enclosure resonance doesn't sound good either and risks driver overexcursion, further reducing reliability and wearing out drivers sooner.
Its an engineering challenge to reliably solder Alu to Cu. Most companies crimp this termination point, since its alot quicker and cheaper than welding. Those who have experience with some older Alu wire VC ScanSpeak drivers know what I'm talking about. The failure point is almost always the lead wire/VC winding junction and its usually covered with a tough adhesive to protect it from the elements. You'll end up damaging the driver trying to repair it and replacements may not be available anymore.
Loading LF drivers with Alu VC windings at their min impedance / min excursion and max current range (close to Fb and/or just above the second impedance peak) produces alot of heat. The overhanging VC windings sitting outside of the magnet gap can't shed their heat as well. Even if the driver doesn't fail, it unevenly heats and fatigue ages the VC. How fatigued it already is becomes a guessing game, as the heat treat isn't visible under the enamel coating unless its discolored, in which case the damage is already done.
The more VC layers and overhang, the worse the problem becomes. The higher temp coefficient further adds insult to injury. Don't even think of running drivers or similar cabs wired in series because power sharing will get even more unpredictable.
What some don't understand is driver loading will vary even by physical location in a sub stack when drivers or enclosures are wired in series. The enclosures running closer to the floor will sink more power than those sitting on top thanks to acoustical loading.
These are all reasons why I won't use LF or midbass drivers with Alu based VC windings for high power PA. Cu wire VCs are the only way to go for these purposes, despite the weight penalty. Its safe to say the only way to improve reliability with Alu windings is derating power by 1/3 to 1/2 published max power spec. Whats the point of having all that extra VC overhang when you can't reliably apply the necessary amount of power long term to utilize it?
I wasn't aware there were so many pro LF drivers out there with Alu wire VCs. That's planned obsolescence IMO and defeats the purpose of having other design compromises in place which hurt SQ while they're supposed to increase reliability (ie. low compliance double spiders, stiffer cones and heavier, higher density VC adhesives). These all hurt sensitivity and in return require more input for given SPL. Drivers used in FLHs with small sealed back chambers and no outside airflow to VC windings suffer the most in this scenario, including other types using smaller chambers in their designs. I won't use anything other than Cu wire based VCs in FLHs because of these reasons.
If you choose to run drivers with Alu VC windings, the only way to increase power handling reliably in sustained higher output operation is monitoring drive with an appropriate DSP using algorithms which carefully limit or reduce input power without excessively compromising SQ and max output in sustained operating conditions, especially in hot humid climates.
I also won't limit myself to proprietary driver dimensions that don't allow for easy last minute substitutions in the field, let alone the higher prices they command up front from the extra engineering they require to design and build. You can't just drop in a similar performing driver in a pinch like you can with a 15" or 18". That flexibility just doesn't exist with weird, non-standard sized drivers.
I agree that most subs with 21"+ drivers require two man handling. If these are designed to be lighter than average weight, SQ will suffer. Low mass, light weight cabs don't sound as good, even when stacked and weighed down.
You can fix some of these problems with concrete blocks, bags of lead shot etc, but thats rather impractical IMO, especially when required to run more subs for higher output and/or lower cutoffs. That really defeats the whole purpose of going with such high tech specialty drivers. EQing lower than enclosure resonance doesn't sound good either and risks driver overexcursion, further reducing reliability and wearing out drivers sooner.
Many great remarks and I agree. RCF discontinzed LF21N551 without a word, so why wouldn't do it to these drivers if they don't sell well after two years.
I have seen issues with CCAW on midrange and midbass drivers, never on subs, but indeed, nuf said.
The 551 has bigger coil and less suspension progression, and that helps a lot, but during the measurements, I didn't like the CCA coil results still. It absolutely DEMOLISHED 21DS115 of the B&C. At extremes 3-4dB louder for program content . That would keep the upgrade in realm of doubling the drivers, not getting better (CCA based) drivers.
But then, there is 21IPAL, and it seems to do the job well. There is so much to tackle things right, and being the guinea pig constantly is expensive.
I have seen issues with CCAW on midrange and midbass drivers, never on subs, but indeed, nuf said.
The 551 has bigger coil and less suspension progression, and that helps a lot, but during the measurements, I didn't like the CCA coil results still. It absolutely DEMOLISHED 21DS115 of the B&C. At extremes 3-4dB louder for program content . That would keep the upgrade in realm of doubling the drivers, not getting better (CCA based) drivers.
But then, there is 21IPAL, and it seems to do the job well. There is so much to tackle things right, and being the guinea pig constantly is expensive.