Series-parallel wiring and sub heat/smell

[Lowkey 10+ year member]

Shouldn't the bass on the EQ be at 0 and the sub level on the head unit turned all the way up? Then adjust the gain from there. Sorry if somebody already brought this up.

Typically bass on the EQ will be at 0 or turned down slightly. Increasing it can introduce distortion. If I were only using sub level on the head unit I would set the gain with it maxed but I'm using a remote gain knob instead.

 

[Buck 5,000+ posts]

Hey bro, check your PM's

 

[Buck 5,000+ posts]

Typically bass on the EQ will be at 0 or turned down slightly. Increasing it can introduce distortion. If I were only using sub level on the head unit I would set the gain with it maxed but I'm using a remote gain knob instead.

I would still turn your subwoofer channel volume at max or most of the way up, and set your gains that way. Having the subwoofer level at 0 on the head unit is going to lower your subwoofer RCA voltage, so you're going to have to turn your gain up more.

I used to install full systems, and I'd always set the subwoofer level on the head unit somewhere between 2/3 and max, and then set the gain on the amp after that.

I had a 9887, and I did my system the same way. I had a very nice bass knob setup with my 9.1's strapped. I like keeping the gains on the amps as low as possible. My 9887 also had an extremely clean signal, so I wasn't really ever worried about clipping by turning the sub channel volume up to max.


Just a note: the more I see how people use bass knobs with clipping indicators as the final solution to how their system is doing, the less I like them. There's always distortion in any audio system. That's just how it goes. I really don't trust a bass knob to tell me what levels of distortion I should be worrying about. I've seen bass knobs indicate distortion at a wayyyy too sensitive level. I'm not sure at what metric they use to indicate clipping, so I wonder how many people have distortion from the signal source and think they're always clipping the amp, when really it's just a slightly clipped heavy bass song, or something. For music, tuning by ear is the way to go, IMO. Idk, I've tuned some loud systems by ear. You can tell when you have issues by the way the subs are playing and the way your voltage at the amp is dropping across your musical bandwidth. You should get to know your system well enough where you don't need any measurement tools besides amp voltage to determine if you're at clipping risk or dirty power risk. I just don't see how these bass knobs are the final solution to determine when your system is at its limits.

 

[hispls 5,000+ posts]

How is cooling a meme? Like Sundown has all sorts of vents for their woofers. 10% less heat is a significant difference, I would think.

Because drilling a couple holes in the pole piece or whatever isn't really pushing that much more air over the coil than just a solid pole piece and the air pushed in and out from under the dustcap and convection is not a terribly efficient way to remove heat from something. 10% heat is nothing when you consider that 10% more power may not even gain 0.2dB on the meter and certainly will not be audible. That and nearly everything we can do to make a coil hold more heat will tank efficiency so you rapidly approach a point where companies produce 6" 8 layer coils with spiffy looking """vents""" so that people can dick-measure about their sub that can "take 8,000W" all the while a DD-Z or Sundown Neo is getting louder off of 1500W. There's a reason the DB Drag leaderboard at the very top has been almost exclusively populated by 3" 4 layer coils for the past couple decades now.

I can't say I have done loads of prototyping of motor designs or anything so I certainly can't quantify it, but I've been told by someone who has that there's not all that much difference and so far I have yet to see any product on the market that's really beating the trend as far as holding heat when you compare physical size/mass/materials of the coil just for an aerodynamic looking frame and a few holes through the top plate. As you say, I think pole venting is mostly to deal with air pressure, and I've heard credible reports of people gaining by gorilla taping over pole vents in their subs (not always of course, but the point is the venting does change performance on tones in a box). Again, what's 10-15% more power when you get to the meter? What's even 20%? You'll need more like 50% to be audible and nobody is claiming that.

The thing people really need to wrap their heads around is how much heat 1200W is. 1200W is the small burner on your stove glowing red. Obviously the stove element is designed to be efficient at turning all energy in into thermal energy out, and there's inherent radiation, conduction, and convection cooling going on by just the basic construction of a loudspeaker and the laws of nature, but beyond that it's still just a shitload of heat to try to shed faster than it's being applied and a loudspeaker is wildly inefficient at turning electrical energy in to acoustic energy out with the stellar performers only coming in in the 2% efficiency neighborhood.

 

[Buck 5,000+ posts]

Because drilling a couple holes in the pole piece or whatever isn't really pushing that much more air over the coil than just a solid pole piece and the air pushed in and out from under the dustcap and convection is not a terribly efficient way to remove heat from something. 10% heat is nothing when you consider that 10% more power may not even gain 0.2dB on the meter and certainly will not be audible. That and nearly everything we can do to make a coil hold more heat will tank efficiency so you rapidly approach a point where companies produce 6" 8 layer coils with spiffy looking """vents""" so that people can dick-measure about their sub that can "take 8,000W" all the while a DD-Z or Sundown Neo is getting louder off of 1500W. There's a reason the DB Drag leaderboard at the very top has been almost exclusively populated by 3" 4 layer coils for the past couple decades now.

I can't say I have done loads of prototyping of motor designs or anything so I certainly can't quantify it, but I've been told by someone who has that there's not all that much difference and so far I have yet to see any product on the market that's really beating the trend as far as holding heat when you compare physical size/mass/materials of the coil just for an aerodynamic looking frame and a few holes through the top plate. As you say, I think pole venting is mostly to deal with air pressure, and I've heard credible reports of people gaining by gorilla taping over pole vents in their subs (not always of course, but the point is the venting does change performance on tones in a box). Again, what's 10-15% more power when you get to the meter? What's even 20%? You'll need more like 50% to be audible and nobody is claiming that.

The thing people really need to wrap their heads around is how much heat 1200W is. 1200W is the small burner on your stove glowing red. Obviously the stove element is designed to be efficient at turning all energy in into thermal energy out, and there's inherent radiation, conduction, and convection cooling going on by just the basic construction of a loudspeaker and the laws of nature, but beyond that it's still just a shitload of heat to try to shed faster than it's being applied and a loudspeaker is wildly inefficient at turning electrical energy in to acoustic energy out with the stellar performers only coming in in the 2% efficiency neighborhood.

Yeah man, like a lot of microwave ovens are 1000-1500 watts. Think about how much heat those can make.

I totally get what you mean when there's no replacement for mass.

That's a really good post you did there man, I like that.

I know with some subs without pole vents, like my older Fi BL's (like 2008 versions), that some people complained about a popping sound or potentially a weird sound on high xmax where there was a bunch of pressure like above the motor pole / behind the dustcap. I never noticed that, personally. I know I popped one of my DC dustcaps off, and they did have a pole vent lol.

This is just another "pick your brain" question: what do you think about the heat dissipation difference between shorter 8 layer 3" coils vs longer 4 layer 3" coils? Do you think the longer 4 layer coils have better heat dissipation? IIRC, that might be one of the design changes between the Zv5 and Zv6 is the Zv6 may be going back to a shorter 8 layer 3" VC vs the Zv5's 4 layer longer VC, but don't quote me on that. That's just a "maybe iirc" comment. I might not be remembering properly.

Neo's do seem to have inherently better cooling properties, there's less motor mass around the coil and often plenty of raw, open air for the coil to interact with. Many neo's seem to not keep the coil purely isolated inside of the motor structure. Yeah, subs like the DD Z 3" coil and the NSv4 and v5 really seem to take the cake for performance. I literally know people that are throwing 5-6kw clamped to the NS's at very low frequencies, and those subs seem to bottom out before the coil gets enough power to fry it. That's insanely awesome to me. Those guys really know what they're doing though, idk if I'd recommend that kind of overpowering to most people.

It just seems to me that there has to be at least some advantage to vents for cooling in huge ferrite motors. Any sort of circulation of air through or around the coil would seemingly help cool the woofer, but I'm not sure to what degree. It would also seem that at lower excursion levels that any VC vent cooling might become ineffective, like at tuning, because the coil isn't moving enough to fully push hot air completely out of the vents before it pulls the hot air back in. Like you sort of said, idk how you touch the capabilities of a neo.

 

[hispls 5,000+ posts]

what do you think about the heat dissipation difference between shorter 8 layer 3" coils vs longer 4 layer 3" coils?

Within reason more layers seems to = more power handling moreso than taller wind width. Bear in mind magnetic field strength is inverse squared so you gain exponentially the tighter you can make the gap so you really sacrifice a lot of motor force to fit those chunkier coils. As it stands my D1.4 coils and D2.8 coils are about 3/4" difference in wind width and I don't notice any difference in how well they hold heat. I definitely noticed the difference when I had experimented with Aluminum coils not holding up as well as the copper to long term heat and I most definitely notice the difference when using larger cones (motor/coils/all else equal). Obviously a 10" cone is going to get a lot more movement out of the same power as an 18" cone so I do run into heat issues faster with larger cone woofers.

I believe those pillar type neo designs aren't built around any special cooling, you just don't need that much material to create and focus the magnetic field in the gap so I suspect they're just a way to save weight and material. In fact all things being equal I wouldn't be surprised if the huge mass of ceramic and steel does as much or more to keep heat off the coil than it being open to the air.

Not sure about pole vents. 4HP had a rather large one as did the 2002 Sig, 2005 used a much smaller pole vent, sadly I didn't get an explanation on why that changed. As you say, many of the great Fi subs had solid pole as did the respectable RE MT and some of the other early top SPL subs, and for what it's worth we rarely or never see it on midrange, full range, or PA drivers. Whatever it is, I have to suspect there's more behind it than cooling

Side by side, across all sizes the coils I use seem to hold more or less the same heat in neo or ceramic motors, any cone size, and even in smaller motors. There's some differences of what gets stinky how quick off the same amp or whatever but broken down to percentage difference in what I'd call "thermal power handling" it's not all that much and certainly should be inaudible. In fact, by the time they're getting smelly you're already well past the point where they're outside their power handling and it's just a matter of time before they fail; from that point it doesn't take much by way of increasing power to dramatically shorten the time until failure.

I would say that when rating power handling you can only about guess as far as mechanical limits (unless things are way over-built) but thermally we cannot in good faith start adding what if's such as what if the person is playing at tuning and the cone is barely moving, what if they're playing 60hz and the cone is barely moving, etc. Subwoofer should be able to play any tone from 20-120hz (at least) when in the correct box, within rated power without failure period.

To be specific, if you say a woofer can take 1000W you should be able to put it in recommended-ish box, clamp a 1000W 50hz sine wave into it in the morning, and when you get back from work it's still playing. This is more or less how Jacob rates. This way you know if a sub comes back broken and it's not an obvious manufacturer defect you KNOW it was abused. It also gives things a reputation to "handle" way more power when someone slaps a 2K amp on their 1200W sub and can pretty much bang any CD they like from start to finish without breaking anything.

 

[Lowkey 10+ year member]

So does Dave use unicon tears or pixie dust to make his 2.5" coils hold 1000W of heat?

I did revisit the webpage and it actually has a 3" coil, I know the SAv2 has a 2.75" coil and is rated 1000W also, so I'm hoping that 1000W is more accurate then we thought.

I've actually learned more than I bargained for in this thread/post. Definitely appreciate everyone's contributions

 

[Buck 5,000+ posts]

Within reason more layers seems to = more power handling moreso than taller wind width. Bear in mind magnetic field strength is inverse squared so you gain exponentially the tighter you can make the gap so you really sacrifice a lot of motor force to fit those chunkier coils. As it stands my D1.4 coils and D2.8 coils are about 3/4" difference in wind width and I don't notice any difference in how well they hold heat. I definitely noticed the difference when I had experimented with Aluminum coils not holding up as well as the copper to long term heat and I most definitely notice the difference when using larger cones (motor/coils/all else equal). Obviously a 10" cone is going to get a lot more movement out of the same power as an 18" cone so I do run into heat issues faster with larger cone woofers.

I believe those pillar type neo designs aren't built around any special cooling, you just don't need that much material to create and focus the magnetic field in the gap so I suspect they're just a way to save weight and material. In fact all things being equal I wouldn't be surprised if the huge mass of ceramic and steel does as much or more to keep heat off the coil than it being open to the air.

Not sure about pole vents. 4HP had a rather large one as did the 2002 Sig, 2005 used a much smaller pole vent, sadly I didn't get an explanation on why that changed. As you say, many of the great Fi subs had solid pole as did the respectable RE MT and some of the other early top SPL subs, and for what it's worth we rarely or never see it on midrange, full range, or PA drivers. Whatever it is, I have to suspect there's more behind it than cooling

Side by side, across all sizes the coils I use seem to hold more or less the same heat in neo or ceramic motors, any cone size, and even in smaller motors. There's some differences of what gets stinky how quick off the same amp or whatever but broken down to percentage difference in what I'd call "thermal power handling" it's not all that much and certainly should be inaudible. In fact, by the time they're getting smelly you're already well past the point where they're outside their power handling and it's just a matter of time before they fail; from that point it doesn't take much by way of increasing power to dramatically shorten the time until failure.

I would say that when rating power handling you can only about guess as far as mechanical limits (unless things are way over-built) but thermally we cannot in good faith start adding what if's such as what if the person is playing at tuning and the cone is barely moving, what if they're playing 60hz and the cone is barely moving, etc. Subwoofer should be able to play any tone from 20-120hz (at least) when in the correct box, within rated power without failure period.

To be specific, if you say a woofer can take 1000W you should be able to put it in recommended-ish box, clamp a 1000W 50hz sine wave into it in the morning, and when you get back from work it's still playing. This is more or less how Jacob rates. This way you know if a sub comes back broken and it's not an obvious manufacturer defect you KNOW it was abused. It also gives things a reputation to "handle" way more power when someone slaps a 2K amp on their 1200W sub and can pretty much bang any CD they like from start to finish without breaking anything.

With the neo’s, I just meant that a lot of them seem to have natural gaps where the coil can be exposed.

I’m fairly certain some pole vents are to release pressure behind the dust cap under high excursion to keep it from blowing off.

I get what you mean with the Rms and the playing 24 hours comparison. That’s a good way to explain that. Being from the music side of thinking, I just see overpowering more, because music seems to be more dynamic, and there’s pauses and stuff, too. I see some dudes run significantly over rms on music for a decent duration of time.

I’ve definitely noticed long term cooling differences between some boxes. Lack of cone travel definitely seems to lead to cooking a coil, like you need at least a certain amount to cool the coil. Anyways, good info!

 

[Bobbytwonames 5,000+ posts]

I would still turn your subwoofer channel volume at max or most of the way up, and set your gains that way. Having the subwoofer level at 0 on the head unit is going to lower your subwoofer RCA voltage, so you're going to have to turn your gain up more.

I used to install full systems, and I'd always set the subwoofer level on the head unit somewhere between 2/3 and max, and then set the gain on the amp after that.

I had a 9887, and I did my system the same way. I had a very nice bass knob setup with my 9.1's strapped. I like keeping the gains on the amps as low as possible. My 9887 also had an extremely clean signal, so I wasn't really ever worried about clipping by turning the sub channel volume up to max.


Just a note: the more I see how people use bass knobs with clipping indicators as the final solution to how their system is doing, the less I like them. There's always distortion in any audio system. That's just how it goes. I really don't trust a bass knob to tell me what levels of distortion I should be worrying about. I've seen bass knobs indicate distortion at a wayyyy too sensitive level. I'm not sure at what metric they use to indicate clipping, so I wonder how many people have distortion from the signal source and think they're always clipping the amp, when really it's just a slightly clipped heavy bass song, or something. For music, tuning by ear is the way to go, IMO. Idk, I've tuned some loud systems by ear. You can tell when you have issues by the way the subs are playing and the way your voltage at the amp is dropping across your musical bandwidth. You should get to know your system well enough where you don't need any measurement tools besides amp voltage to determine if you're at clipping risk or dirty power risk. I just don't see how these bass knobs are the final solution to determine when your system is at its limits.

Finally, somebody agrees with me. Subwoofer level set at max on the head unit. That's pretty basic stuff.

 

[Bobbytwonames 5,000+ posts]

Typically bass on the EQ will be at 0 or turned down slightly. Increasing it can introduce distortion. If I were only using sub level on the head unit I would set the gain with it maxed but I'm using a remote gain knob instead.

Sub level set at max on your head unit and then adjust your gains on the amp.

 

[hispls 5,000+ posts]

I just see overpowering more, because music seems to be more dynamic

Now try to define "music". Are we talking about Gene Autry's Greatest Hits? Michael Jackson's Thriller? The Wanamaker Organ Centennial Concert? Some 80IQ knuckle dragger grunting about his genitals and committing crime over a 40hz clipped sine wave?

I did revisit the webpage and it actually has a 3" coil, I know the SAv2 has a 2.75" coil and is rated 1000W also, so I'm hoping that 1000W is more accurate then we thought.

I've actually learned more than I bargained for in this thread/post. Definitely appreciate everyone's contributions

I could not find much details about those except some old forum posts, but I would suggest that if your subs are getting smelly, regardless of what you read anywhere or who told you what, you are putting heat into them faster than your woofers can shed that heat, there is literally no other explanation. Assuming you're not doing something terribly wrong in wiring the coils wrong or similar, the answer is going to boil down to either buy more robust woofers, or use some restraint on the volume knob and give things a rest for a bit after pushing hard like that.

 

[Buck 5,000+ posts]

Now try to define "music". Are we talking about Gene Autry's Greatest Hits? Michael Jackson's Thriller? The Wanamaker Organ Centennial Concert? Some 80IQ knuckle dragger grunting about his genitals and committing crime over a 40hz clipped sine wave?

We're talking like rap bass. A lot of dudes that I know that have ran over RMS are all bass heavy rap listeners, a lot of them listen to stupid low end stuff. Heavy bass like in EDM or rap or any modified and slowed music. You gotta remember, what I call music is what the customer calls music. I tend to like a lot of music my customers listen to, in general. I do get a fair amount of people wanting to bang on metal, like fast kick drums and stuff. The box design can change power levels at different frequencies, so that's something I try to take into account, depending on the overall setup. I know this isn't quite music, but I've also seen dudes run stupid power doing the 1 minute demos for competition, I forget what that's called. I know that's not satisfactory to be compared to long term RMS, but I guess my point is the system can take more power in some situations and using the system a certain way. That's why people need to truly learn their system and what's going on, IMO. I'm definitely not a woofer builder and am always learning bc I'm self-taught.

That coil gap thing you reminded me of about it being exponential had me thinking. I was talking to a certain audio company employee about the difference in gaps between woofers and how some companies pay the extra $$$ to develop their woofers with a much tighter gap (tighter tolerances all around with all machining iirc).

Do you know how much difference in heat building a smaller gap has vs a bigger one? If you could do one of your explanations on that, that would be dope. I wonder if companies choose to have a slightly bigger coil gaps than pay more money to develop the woofer more. It seems the tighter coil gap would mean every other part of the woofer would have to be more precise to not get rubbing, get everything aligned more precisely, etc.

 

[hispls 5,000+ posts]

I know this isn't quite music, but I've also seen dudes run stupid power doing the 1 minute demos for competition,

Most orgs have at least one "music" class where it's an average SPL over time that's counted, either max or trying to get just to some number without going over. About a year ago the org we have here in the northeast started a 3 minute average, highest score with a wall and no wall class only. I've also seen rookie classes using combined score of burp and music or only allowing music but using only the peak SPL.

In days past when an org had "music" class it was limited to commercially available music that one could conceivably go out to Best Buy or some record store and buy a commercially produced copy of. Some even had their own "official" CD with various tracks that everybody had to use for metering which was good for the orgs making a few bucks off of CD sales and also so that everyone was on an equal footing. These days there's a hundred guys online who are "DJ ______" who do all manner of bass boosting ranging from some half decent remixed bass lines to just laying a test tone over pretty much any type of song you can think of, so that seems to be out the window. I still use a handful of songs that you could actually go buy on i-tunes or find on a CD, but they are inferior to DJ Test Tone or whatever dumb other ****. The point being even if you only define "music" as something I could go buy at a record store.... if they still had record stores.... there's still some stuff that's just a 3 minute sine wave. There's even a Metallica track I use for 54-55hz for 30 seconds that works really nicely but would be hurtful for someone trying to run 3X rated power to their subs if 54hz was Z-min of their system.

Yes, most of the SPL oriented subs use a tight gap (that's the SPL option with Fi and similar). It definitely requires tight tolerances in manufacturing and assembly and overall may make for less durable woofer as far as getting coil failure from outgassing bubbling a former or the coil rocking from slight misalignment in assembly or just a bad pressure spot inside the box. Taken to the extreme you can probably shave it even tighter if you figure for only 3 seconds of tone and don't even worry about allowing a few thousandths for expansion due to heat in the coil.

DD 95XX is now using some oddball 3" and a bit coil and a much larger gap than older models while the prototype we saw of the new Kicker Solo X has a very tight gap. More motor force doesn't necessarily = a better sounding sub nor a sub that really excels below 40hz so there's a lot of other design goals in play when few if any subs on the market are exclusively only being used for 3 second burp applications. How many subs do you recon are being prototyped with the ONLY question being asked being "does it gain?"

I have no data on cooling for this, could go either way or be all the same, it might be that the gap/pole being closer can pull radiated heat away from the coil better or it may be that having more air around it somehow allows better air exchange, or it could be that if the volume in the gap is very small and the space between top and pole piece is really tight that the velocity of the air flowing through with each stroke will be greater and cool greater, or at some point is it too tight that the air inside is just rarified and compressed and not even exchanged? Might just be a wash or might be something but not enough that it really makes any practical difference. Again, I haven't seen anything on the market that's really beating expectations when comparing similar dimension coils against the rest of the field. I can definitely say that the tighter gap stuff is really easy to **** up when assembling softparts so just knowing the limitations of your 10 year old Chinese slave workforce may well come into play there.