18" Dayton Ultimax Dipole Subwoofers and Crown K1 Amp Mini DSP Confusion

Nakean

Nakean

Junior Audioholic
Hello everyone,

I finally got my hands on some Dayton Ultimax 18"s. Not one but two and already in a dipole box. I was curious about Dipole configuration since the reason I sold my pc2000 was it sounded too boomy and the room nodes are a little nuts in my particular room (odd-shaped room with openings.)

The dipole setup does not pressurize the room at all and is very directional. There aren't crazy peaks in the room response either. I like it but.......

What I don't understand is the seller said the subs were wired so the amp would see an 8 ohm load.

Questions:

  1. Is there even a wiring setup in which two 2ohm dual coil subs can show 8 ohms to the amp in mono?
  2. Should I wire these up as bridged 8ohm setting on the K1 if so (that would be a healthy 1,100 watts)
  3. My mini DSP only outputs .9 volts anyway to fix this as the K1 wants to see 1.4 volts or do I need too upgrade to the MiniDSPHD?
  4. If I play at moderate levels while I'm waiting for MiniDSPHD or whichever one runs 1.4 volt output can I damage the subs with no HighPass Filter
  5. How should I set the Highpass filter (do I need one to protect the Sub?) Guessing 18hz but what about the roll off?
  6. Is this enclosure design not designed for large SPL output? The bass is there but the sound is just so different.
  7. dipole 3.jpg
 
lovinthehd

lovinthehd

Seriously, I have no life.
I'd think about making two boxes for the drivers....or a dual opposed.
 
ryanosaur

ryanosaur

Audioholic Spartan
This build, configuration... the choices the guy made... don't make sense.

I wouldn't go down that path if it were my dollar.

I agree with Lovin'! Scrap that box and get those drivers repurposed into a better configuration.

BTW, Low frequency drivers don't exist as dipole... they emit such large and powerful waves that they are effectively omnidirectional. I'm afraid to ask for more story about this... much less what you paid.
Did you get the modeling parameters, measurements, any other documentation about this guy's build?
 
Nakean

Nakean

Junior Audioholic
This build, configuration... the choices the guy made... don't make sense.

I wouldn't go down that path if it were my dollar.

I agree with Lovin'! Scrap that box and get those drivers repurposed into a better configuration.

BTW, Low frequency drivers don't exist as dipole... they emit such large and powerful waves that they are effectively omnidirectional. I'm afraid to ask for more story about this... much less what you paid.
Did you get the modeling parameters, measurements, any other documentation about this guy's build?
Don't be afraid my good sir. I spent $400 for the drivers plus the box and the K1 amp so I know I came out ahead. A single driver alone is close to this in price. I sold my pc2000 so I could use those funds only to pay for what I purchased. Single Parts express box and driver would have cost far more than this. My idea is to get the best out of this configuration for now and eventually purchase two sealed boxes from parts express.

Trust me...these things give off almost nothing at the driver cone and magnet side compared to the open sides. Using REW the frequency changes a TON by just spinning the driver in place.

If this is the driver, it has two 2-ohm voice coils. Those would be wired in series to make a 4-ohm load. Two drivers would then be wired in series to become an 8-ohm load.


Regards,
Wayne A. Pflughaupt
Thank you!!! For now I will just run the amp bridged with the 1100 watts on tap at 8 ohms
I'd think about making two boxes for the drivers....or a dual opposed.
That's the plan eventually, I think. Just thought I would try and get the most out of these in their current state first.
 
Nakean

Nakean

Junior Audioholic
This build, configuration... the choices the guy made... don't make sense.

I wouldn't go down that path if it were my dollar.

I agree with Lovin'! Scrap that box and get those drivers repurposed into a better configuration.

BTW, Low frequency drivers don't exist as dipole... they emit such large and powerful waves that they are effectively omnidirectional. I'm afraid to ask for more story about this... much less what you paid.
Did you get the modeling parameters, measurements, any other documentation about this guy's build?
With this setup do I need an 18hz lowpass filter? What db roll off of so?
 
TLS Guy

TLS Guy

Audioholic Slumlord
With this setup do I need an 18hz lowpass filter? What db roll off of so?
Well I don't think you should use them at all in that configuration. If the speakers are wired in phase, then there is no restraining force on the drivers and you will destroy them. If the drivers are wired out of phase, there will be high restraining force but the drivers are cancelling each other out. Either way you absolutely can NOT use that box.

If you are sensible we can design you two sealed boxes, or one box with opposed drivers. Those drivers are best for sealed application. However as in all sealed alignments you need equalization and a high pass filter. I already have a design for the optimal sealed box, and if you used two drivers in the box, then the box would be doubled in size.
 
lovinthehd

lovinthehd

Seriously, I have no life.
Well I don't think you should use them at all in that configuration. If the speakers are wired in phase, then there is no restraining force on the drivers and you will destroy them. If the drivers are wired out of phase, there will be high restraining force but the drivers are cancelling each other out. Either way you absolutely can NOT use that box.

If you are sensible we can design you two sealed boxes, or one box with opposed drivers. Those drivers are best for sealed application. However as in all sealed alignments you need equalization and a high pass filter. I already have a design for the optimal sealed box, and if you used two drivers in the box, then the box would be doubled in size.
What would be the purpose of the high pass filter in a sealed sub?
 
TLS Guy

TLS Guy

Audioholic Slumlord
What would be the purpose of the high pass filter in a sealed sub?
Well all sealed subs have a high f3. So you have to add 6db boost per octave below F3. So if you don't put a high pass filter around the xmax of the driver you expose it to damage from over excursion. That boost is why sealed subs require such high powered amps.
 
ryanosaur

ryanosaur

Audioholic Spartan
Well all sealed subs have a high f3. So you have to add 6db boost per octave below F3. So if you don't put a high pass filter around the xmax of the driver you expose it to damage from over excursion. That boost is why sealed subs require such high powered amps.
Thanks. This may be the best explanation of this I've heard. :)
 
lovinthehd

lovinthehd

Seriously, I have no life.
@TLS Guy I'd seen HPFs mentioned many times for ported to control driver below tuning, but not for sealed subs particularly. Doesn't the box itself act as a hpf of sorts in a sealed sub? Or does that simply depend on the volume of the box and driver used?
 
Pogre

Pogre

Audioholic Warlord
I think it's likely the boomy bass from the PC2000 is more a setup issue than the sub itself. Most rooms are odd shaped or end up that way with furnishings, hallways, doorways, etc.. I have a labyrinth of open rooms, a hallway and vaulted ceilings to boot. Likewise pretty much every room has its own crazy room nodes too. The PC2000 is a pretty damned good sub. Best way to deal with boom or uneven frequency response is with optimum placement, going dual or both. Maybe some room correction or DSP for those boomy peaks.

I would have have sprung for a 2nd PC2000 instead of buying that funky contraption you ended up with. That design is a head scratcher. I have no idea what the goal is there. Ryan already made the point about calling it a dipole. That doesn't really apply with subs. No matter what design it is tho, below 80 hz it becomes increasingly difficult to pinpoint the source or direction for humans. If your experiencing directionality you're likely using a high crossover/low pass filter.

You do have 2 decent drivers now tho, and I'm with the folks saying to scrap that box and build 2 separate enclosures for them. You can still use a single amp to power them both. I think it's a solid plan for salvaging your purchase and can help deal with with room modes too. 2 birds, 1 stone!
 
Nakean

Nakean

Junior Audioholic
I think it's likely the boomy bass from the PC2000 is more a setup issue than the sub itself. Most rooms are odd shaped or end up that way with furnishings, hallways, doorways, etc.. I have a labyrinth of open rooms, a hallway and vaulted ceilings to boot. Likewise pretty much every room has its own crazy room nodes too. The PC2000 is a pretty damned good sub. Best way to deal with boom or uneven frequency response is with optimum placement, going dual or both. Maybe some room correction or DSP for those boomy peaks.

I would have have sprung for a 2nd PC2000 instead of buying that funky contraption you ended up with. That design is a head scratcher. I have no idea what the goal is there. Ryan already made the point about calling it a dipole. That doesn't really apply with subs. No matter what design it is tho, below 80 hz it becomes increasingly difficult to pinpoint the source or direction for humans. If your experiencing directionality you're likely using a high crossover/low pass filter.

You do have 2 decent drivers now tho, and I'm with the folks saying to scrap that box and build 2 separate enclosures for them. You can still use a single amp to power them both. I think it's a solid plan for salvaging your purchase and can help deal with with room modes too. 2 birds, 1 stone!
I purchased the subs solely for the subs and the amp. Figured they were already in a box and didn’t have the funds for the Flat pack and equipment to build it just yet. Price was too good to pass up on the subs themselves. Box didn’t cost anything so figured I’d hook it up and see how it sounded.

I have an sb2000 and like the sound from it far more than sound from my pc2000. I figure since everything else is equal, I prefer the sealed sub sound. Unfortunately the sb2000 doesn’t have quite enough output for my room. Enter Ultimax18. Was going to do 15 but 18’s were hardly more expensive and at $150 each (what I paid for these) I couldn’t pass them up.

I will go sealed but not for another month or so. Didn’t want to break my boom boom woofers in the meantime.

sounds like this box is complete crap.Dang.
 
Nakean

Nakean

Junior Audioholic
Well I don't think you should use them at all in that configuration. If the speakers are wired in phase, then there is no restraining force on the drivers and you will destroy them. If the drivers are wired out of phase, there will be high restraining force but the drivers are cancelling each other out. Either way you absolutely can NOT use that box.

If you are sensible we can design you two sealed boxes, or one box with opposed drivers. Those drivers are best for sealed application. However as in all sealed alignments you need equalization and a high pass filter. I already have a design for the optimal sealed box, and if you used two drivers in the box, then the box would be doubled in size.
Thank you for taking the time to respond. Sucks that this box is crap. They are wired up out of phase I believe. One moves one way and the other moves the other direction when hooked up to a AA battery. So at least they’re not destroying each other.
I wonder about the cancelation. They still make bass. Albeit much quieter at the same levels as my sb2000. Is this the cancelation you speak of.
 
TLS Guy

TLS Guy

Audioholic Slumlord
@TLS Guy I'd seen HPFs mentioned many times for ported to control driver below tuning, but not for sealed subs particularly. Doesn't the box itself act as a hpf of sorts in a sealed sub? Or does that simply depend on the volume of the box and driver used?
The box obviously does control cone excursion, as the driver compresses and decompresses the air. However the boost required is a so great there remains and problem, as every 3db increase in equalization doubles the power to the driver. So if the F3 is forty Hz, then at 20 Hz the power is X 4. Now many movies now contain frequencies as low as 12 Hz. So that is X 8 power. That needs limiting.

Now actually other forms of loading actually provide greater back pressure to the cone than a sealed enclosure. I know that is counter intuitive,, but that is the physics of it.

At tuning a ported enclosure has such pressure that the cone virtually stops still and almost all of the sound is emitted from the port. No boost is needed and can not be applied. Sure below tuning the driver decouples from the box, and a high pass filter may be required. However this decoupling is gradual and progressive and more often than not a high pass filter is not required.

With pipes that I favor, the pressure in the region of the driver is enormous, and in a tapered pipe the frequencies are very broad. I have observed my drivers producing prodigious bass output and the cones seem to be barely moving. This is to be expected, as in a closed Gedeckt organ pipe, there is an antinode of pressure and a node of displacement. This is obvious as air can not move through a solid obstruction. On the other hand at the open end there is a node of pressure and an antinode of air displacement. So that is where the sound emanates from. No high pass filter is required. The most efficient way of loading a speaker is with a horn. Here the back pressure on the driver is enormous, and the air displacement at the mouth enormous. Again no high pass filter is required and only low powered amps are required to produce large sound pressure levels.

I well remember when Donald Chave of Lowther was sent for, when there was gig in St. Paul's cathedral London in the pre solid state era for a concert. The biggest outfits of the time could not do the job. He filled St. Paul's cathedral with four horn loaded 6" drivers and 40 watts of amp power. That was remarked upon in many articles following the concert. This should not surprise when you think of the ruckus one individual can create with a trumpet, trombone or French Horn.

So in pecking order the most efficient ways to load a speaker from most to least, is horn, pipe, ported(Helmholtz resonator) and a very distant last a closed box.. A closed box should only really be considered in a case where you absolutely don't have room for something bigger. It should be considered the loading of last resort.
 
Nakean

Nakean

Junior Audioholic
So in pecking order the most efficient ways to load a speaker from most to least, is horn, pipe, ported(Helmholtz resonator) and a very distant last a closed box.. A closed box should only really be considered in a case where you absolutely don't have room for something bigger. It should be considered the loading of last resort.
I’m just trying to figure out why efficiency is the end all be all with people. Perhaps I’m generalizing but it sure feels like it. I’ve seen other instances of this box Design online from other people’s builds. Yes it’s is inefficient, no it does not pressurize a room. But it does produce bass and it does excite far less room nodes. it’s directional in that I can rotate the box and get completely different room responses without moving the box around the room. I’m trying to make the most out of it without breaking my drivers until I get a couple of sealed flat packs next month.

Almost none of my questions were answered.
Do I need a high pass filter? If so what db roll off?
 
TLS Guy

TLS Guy

Audioholic Slumlord
I’m just trying to figure out why efficiency is the end all be all with people. Perhaps I’m generalizing but it sure feels like it. I’ve seen other instances of this box Design online from other people’s builds. Yes it’s is inefficient, no it does not pressurize a room. But it does produce bass and it does excite far less room nodes. it’s directional in that I can rotate the box and get completely different room responses without moving the box around the room. I’m trying to make the most out of it without breaking my drivers until I get a couple of sealed flat packs next month.

Almost none of my questions were answered.
Do I need a high pass filter? If so what db roll off?
Well the response of that horror is impossible to calculate. It will pressurize the box in the middle but not the room. If you are not adding boost you probably do not need a high pass filter.

The contraption will have peaks and valleys all over the response. The design makes absolutely zero sense and is total garbage.
 
Pogre

Pogre

Audioholic Warlord
I purchased the subs solely for the subs and the amp. Figured they were already in a box and didn’t have the funds for the Flat pack and equipment to build it just yet. Price was too good to pass up on the subs themselves. Box didn’t cost anything so figured I’d hook it up and see how it sounded.

I have an sb2000 and like the sound from it far more than sound from my pc2000. I figure since everything else is equal, I prefer the sealed sub sound. Unfortunately the sb2000 doesn’t have quite enough output for my room. Enter Ultimax18. Was going to do 15 but 18’s were hardly more expensive and at $150 each (what I paid for these) I couldn’t pass them up.

I will go sealed but not for another month or so. Didn’t want to break my boom boom woofers in the meantime.

sounds like this box is complete crap.Dang.
I'll repeat, I suspect setup/integration is the problem you had with the PC2000. The whole "sealed is better for music" is a myth that needs to go away. I think some positional eq and/or a 2nd PC would have helped a lot. I would never go with sealed unless room was a major issue.
 
Nakean

Nakean

Junior Audioholic
I'll repeat, I suspect setup/integration is the problem you had with the PC2000. The whole "sealed is better for music" is a myth that needs to go away. I think some positional eq and/or a 2nd PC would have helped a lot. I would never go with sealed unless room was a major issue.
Room WAS a major issue. I had both pc2000 and sb2000 subs. I spent weeks moving them around and running rew. Why can’t people just accept some enjoy a different setup then themselves. The world is not black and white. Second pc was not an option anyway.
 
Nakean

Nakean

Junior Audioholic
Well the response of that horror is impossible to calculate. It will pressurize the box in the middle but not the room. If you are not adding boost you probably do not need a high pass filter.

The contraption will have peaks and valleys all over the response. The design makes absolutely zero sense and is total garbage.
So you haven’t seen measurements, haven’t heard the box and believe it is impossible to calculate the response.....but....it’s god awful. You see the issue there? Lol.

You’re probably right but can you see how frustrating it is to have all these people tell me that I should have kept my pc2000 even though I didn’t like it because I just didn’t set it up properly in my room when they don’t know what my room sounds like, have zero idea how many positions I put it in and how many hours and days I spent running rew. Even with then response I liked, I didn’t like the sound compared to my sb2000. Same driver, same 550 watt rms plate amp same room positions. Sb2000 just struggled at the levels I sometime play it at. Ultimax will be able to do it in its sleep. I’m playing with the box I have now for a little bit.

Thank your for the info on the high pass. Currently I’m getting a flatish response without any eq in my room. I’ll keep playing, cause that’s all this is. I’m just having a bit of fun. It’s a different sounding bass than I’ve ever heard and hard to explain. It’s all there but doesn’t thump and it doesn’t excite the room. It’s bass but it’s different and until you’ve heard it, (in my room) you can’t really know what it sounds like.
 

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