[Kevin Haskins]

I know this is a loaded question and there will be a diversity of opinion because people have different priorities.

I'm once again working on a finished subwoofer design.   I want some input from people as to what they consider are the most important attributes.

I assume everyone will want a musical sub. What I'm looking for is size constraints, sealed vs. vented, finish options, input on layout (front firing vs. down firing) and some of the features you would like to see in the signal processing area.   Also, what do you consider as appropriate for the output level at a given frequency, overall extension, and any input you may have considering pricing and technical performance.

Any input is appreciated!   

[gooberdude]

I've purchased 3 new subs in the last few months, finally settled on a stereo pair. 

1 option that would be neat is a remote control.  the ability to control the volume of both subs simultaneously with the push of 1 button would be sweet.

Having a parametric eq, calibration mic and side firing would be a few others to add to the wish list.

I'm really satisfied with the subs i settled with, but they do have a flaw...the on/off switch has no 3rd setting that turns the amp on when a signal is present.  i think its a Standby function?  anyways, that should be standard as well.

[Kevin Haskins]

I've purchased 3 new subs in the last few months, finally settled on a stereo pair. 

1 option that would be neat is a remote control.  the ability to control the volume of both subs simultaneously with the push of 1 button would be sweet.

Having a parametric eq, calibration mic and side firing would be a few others to add to the wish list.

I'm really satisfied with the subs i settled with, but they do have a flaw...the on/off switch has no 3rd setting that turns the amp on when a signal is present.  i think its a Standby function?  anyways, that should be standard as well.

The remote control we have on the design list.   Controlling two reliably is a more difficult task.   Both have IR ports but you could get them out of sync via one receiving the signal and the other not.   

The PEQ, calibration mic are on the list.   Can I ask why side firing?   I was planning on downfiring.

The standby function is a good idea.   I assume that helps with turn-on thump when the system is powered up.   

[gooberdude]

I gotta tell you the 3 subs i've recently purchased were the 1st i've owned for home use, so take my recomendations with a grain of salt.  Also, they weren't 'hi-end' but made well.  But, getting used to their operation has left me with some indellible impressions as to how using subs could be made simpler in a few areas...

When i was initially looking for subs, lots of guys recomended side firing...my 1st was down firing.  It didn't sound right, or work with my room, until i incorporated a really expensive mount.    The stereo pair I bought are side firing (face left and right in my room) and just sit on the carpet with no troubles.  this might be due to my floor: poured concrete with padded carpet on top, dunno.  My side firing subs each wegh 60 lbs and the down firing weighed 40...   other than that issue, i can't say one style sounds or performs better due to lack of experience/knowledge.

With the remote function, have you heard of any slave set-ups, meaning one sub is tied into the other?  ie, the remote would control the IR for one sub and the 2nd sub would be connected via a cable..   i've not seen one like this, just an idea.

One other intersting note is the way each of the 2 difft subs i've owned deal with the signal connections, when comparing how the subs react differently with speaker or RCA level connection.  One sub designer told me they made the RCA input more sensitive than the sp posts....the 2nd designer told me he did the opposite.   no clue which is best, just interesting that designers look at this aspect differently.

Kevin, last night i tried a weird tweak on my subs that was based on my expereince doing the same thing to a pair of Hawthorne SI's a few nights ago....i ran a single strand of cat5 wire from the speaker basket to a negative speaker post, grounding the drivers.  the bare end of the wire was taped to the basket and the other bare end shoved into neg post...i did not scrape anything to get to bare metal.   it produced the same improvement that other grouding tweaks have done in the past, which is removing some slop/noise & seemingly making the driver sound 'faster' & more musical.   this might be another thing to consider.   maybe has something to do with static electricity build-up or something????  no clue, but it made an audible improvement.



matt

[gooberdude]

forgot one thing....  i have no idea if the Standby affects the thump, it probably does though.  My issue is now there's 2 more power switches to turn off at night.   Since my subs are in far corners from one another and behind assorted cabling mazes, its a bit of a pain.

I really sound like a lazy guy!!

The Hsu sub i used orignally was sweet in that the sub would kick on a few seconds after i dropped the needle.   

Since Com-Ed has raised my electric rates by 40%, i'm a bit more conscious of wasting power.

[Kevin Haskins]

forgot one thing....  i have no idea if the Standby affects the thump, it probably does though.  My issue is now there's 2 more power switches to turn off at night.   Since my subs are in far corners from one another and behind assorted cabling mazes, its a bit of a pain.

I really sound like a lazy guy!!

The Hsu sub i used orignally was sweet in that the sub would kick on a few seconds after i dropped the needle.   

Since Com-Ed has raised my electric rates by 40%, i'm a bit more conscious of wasting power.

Most of the plate amps in stand-by mode still consume 10-15W of power.   The auto-on feature only really toggles the output stage in most cases.    The Class D solution we are using idles at about that same power consumption (and its 1000W amp).   You would save maybe 5W (night light) type of power by having something that could toggle the output stage on/off.   I'm not sure its worth the added complexity.   

[crossroadazn]

How about a sub with mic built-in and processor adjust by it self no matter where it sits in the room. 

[Kevin Haskins]

How about a sub with mic built-in and processor adjust by it self no matter where it sits in the room. 

We have an auto-EQ function that uses a test microphone and a frequency sweep that measures room response and then sets two fully adjustable Parametric EQ bands (down to 1/12th octave spacing & up to 30db of cut).     You can even plug into your PC via a USB port and view the measured room response on your PC.    You can manually override and adjust all Auto EQ settings.   

Is that enough?

[Bob in St. Louis]

One requirement:
......Flat to the mid/low teens. Twelve or thirteen ought to be enough.

OK, two requirements, I have to be able to afford it.

Bob

[Kevin Haskins]

One requirement:
......Flat to the mid/low teens. Twelve or thirteen ought to be enough.

OK, two requirements, I have to be able to afford it.

Bob

That is one of those design choices you make.   Typically I'd design an accurate sound quality type subwoofer with the bottom-end having some slight roll-off to compensate for room gain.   It's one of those design choices you make as a designer about how much to compensate.   Many of the HT based subs tend to be very flat anechoic and then when you put them in room they end up with a little lift on the bottom.   

I'm designing a variable linkwitz transform type function that allows the user to adjust how much extension they want and the final Q.   It is a menu based system where you can set the subwoofer for maximum extension (good for about 16Hz in-room) or maximum output (extension to 25hz but more headroom from there up).   I'll probably have three menu choices.  One for max extension, one for maximum output and one for somewhere in between.

Price will be very affordable.   I'm not interested in designing something in the many kilobuck range.   

[Carl V]

Kevin,

It sounds like you have some good ideas.
I like most of what you have posted.

I have a down firing Sealed Tumult with
22" sides....powered by an Adire Modified
ADA1200.  I asked for maximum extension
to about 18-20Hz with Low Q.  Only problem
with these parts is that I didn't account for
the large & deep magnet interfering with the
large Toroidal Transformer on the ADA1200.
So I had to mount the Plate map upside down.  
It's in nice Walnut.  It's my version of a WMD.

I'd like something similar...perhaps 20x22x24
Sealed...down firing....mic's, PEQ....LT circuit.
and I like the 2 -12dB/octave slopes yileding
24 if I needed it.

[konut]

You might want to determine what the maximum size that is allowed by the major carriers and limit the delivery box to that size.
I will not buy anything other than a sealed design. Thats my preference based on the ported and folded designs I've heard. I do admit I haven't heard any of the late model ported designs and do know its possible to design a good one, but haven't had a chance to hear one. Sealed designs demand a large amp, though you might want to raise efficiency with a passive radiator. The  3 menu user defined option is an excellent idea. I wonder why we haven't seen that up till now. I also think  that 24db per octave HP and LP filters are the best way to integrate tothe mains.

[Kevin Haskins]

Kevin,

It sounds like you have some good ideas.
I like most of what you have posted.

I have a down firing Sealed Tumult with
22" sides....powered by an Adire Modified
ADA1200.  I asked for maximum extension
to about 18-20Hz with Low Q.  Only problem
with these parts is that I didn't account for
the large & deep magnet interfering with the
large Toroidal Transformer on the ADA1200.
So I had to mount the Plate map upside down. 
It's in nice Walnut.  It's my version of a WMD.

I'd like something similar...perhaps 20x22x24
Sealed...down firing....mic's, PEQ....LT circuit.
and I like the 2 -12dB/octave slopes yileding
24 if I needed it.

Your not the only one who ran into that problem.   The 15" model I'm designing will almost have the output of the WMD.   Its going to come up a 1-2db short in maximum output.    It will have much more extension though simply because we have a new preamp/processor that gives us a lot more flexibility.

I want to point something out about the 24db (4th order) variable crossovers.    They are tough to build right.   Adire did a good job in that they had two independent 12db crossovers that didn't interact with each other.   The fact of the matter is it is very tough to design a variable crossover with passive components that does exactly what it is supposed to.   Most plate amps on the market are absolutely horrible.   They don't work over anywhere near the range listed and their LP crossover typically interacts with the gain of the product.     In other words they suck.

Another characteristic we live with is the fact that pretty much all hardware based solutions (DSPs can change stuff in software) offer just an electrical correction.   They have don't take into account the actual acoustic output of the system (which may be rising or falling) and hence you almost never see a true 2nd order acoustic response from a subwoofer using a standard plate amp.

We are going to solve that.   Our crossover will function over the range needed as advertised and the acoustic response is going to EXACTLY match what you set on the plate amp.   And the acoustic response I'm aiming for will be a 2nd order acoustic function.    Minimizes phase shift and will provide the same response as the 4th order electrical solutions you see.

[Kevin Haskins]

You might want to determine what the maximum size that is allowed by the major carriers and limit the delivery box to that size.
I will not buy anything other than a sealed design. Thats my preference based on the ported and folded designs I've heard. I do admit I haven't heard any of the late model ported designs and do know its possible to design a good one, but haven't had a chance to hear one. Sealed designs demand a large amp, though you might want to raise efficiency with a passive radiator. The  3 menu user defined option is an excellent idea. I wonder why we haven't seen that up till now. I also think  that 24db per octave HP and LP filters are the best way to integrate tothe mains.

I like people who think like you.   Practical! 

I'm thinking two sizes:   12" model with 16" (W) x 18" (D) x 19" (H) dimensions.    15" model with 18" (W) x 22" (D) x 21" (H).    Both sizes are easily UPSable.   

You have not seen those types of solutions because they are very difficult and expensive to implement with standard pots, opamps and old-fashion analog design tools.   They could be done with DSPs but you don't see a lot of DSP based plate amps on the market because its EXPENSIVE to design DSP based systems.    The big guys like Velodyne have done so but it is harder for smaller companies to cough up the capital and to hire DSP programmers and engineers knowledgeable about the task.

[opnly bafld]

I will not buy anything other than a sealed design.
Sealed designs demand a large amp, though you might want to raise efficiency with a passive radiator.

 

Lin

[Voodoo Rufus]

I assume everyone will want a musical sub. What I'm looking for is size constraints, sealed vs. vented, finish options, input on layout (front firing vs. down firing) and some of the features you would like to see in the signal processing area.   Also, what do you consider as appropriate for the output level at a given frequency, overall extension, and any input you may have considering pricing and technical performance.

Sealed vs. vented: Sealed gives a smaller box size, but as long and the solution is not too large and sounds good, it matters little.

Finish: Not too particular as long as there's some nice wood veneers available.

Signal processing: For a sealed setup, an LT would be nice. The Adire ADA series looks like a natural solution. I think a built in mic-based self-eq seems a bit on the pricey and complex side of things.

Appropriate output level: For music, nice and flat to the 20s. For movies, a little extra thump is nice, but not mandatory. Not too familiar on how loud dB levels are, but if I feel like cranking the music up it can peak to the 100dB level (when I measured with a Rat Shack SPL meter on Klipschorns). Of course this is not possible in subdivision or apartment environments without irritating neighbors.

Overall pricing: $1K?

I have the sneaking suspicion this sub will include the EX drivers.....

[Kevin Haskins]

I assume everyone will want a musical sub. What I'm looking for is size constraints, sealed vs. vented, finish options, input on layout (front firing vs. down firing) and some of the features you would like to see in the signal processing area.   Also, what do you consider as appropriate for the output level at a given frequency, overall extension, and any input you may have considering pricing and technical performance.

Sealed vs. vented: Sealed gives a smaller box size, but as long and the solution is not too large and sounds good, it matters little.

Finish: Not too particular as long as there's some nice wood veneers available.

Signal processing: For a sealed setup, an LT would be nice. The Adire ADA series looks like a natural solution. I think a built in mic-based self-eq seems a bit on the pricey and complex side of things.

Appropriate output level: For music, nice and flat to the 20s. For movies, a little extra thump is nice, but not mandatory. Not too familiar on how loud dB levels are, but if I feel like cranking the music up it can peak to the 100dB level (when I measured with a Rat Shack SPL meter on Klipschorns). Of course this is not possible in subdivision or apartment environments without irritating neighbors.

Overall pricing: $1K?

I have the sneaking suspicion this sub will include the EX drivers.....

You will have your choice of finish so long as it is black.     Size is managable.... think Rava and a little bit bigger for the 15" model.

Price is going to be well under $1K.   Your guess on the driver is right and we will be using the amplifier section of the ADA1200 but a different signal processing solution.   Its something that will knock your socks off.    It allows some user choice for level of extension, just trading some maximum output (and we have plenty to trade) for lower-end extension.   The 15" model should be flat anechoic to 20Hz and in-room you should see extension well into the 15-16Hz range.   

Maximum output will be just about like the WMD that Tom Nousaine measured which had a maximum output at 111db @ 32Hz and within a couple db of that across its bandwidth.

[Bob Reynolds]

I want to point something out about the 24db (4th order) variable crossovers.    They are tough to build right.   Adire did a good job in that they had two independent 12db crossovers that didn't interact with each other.   The fact of the matter is it is very tough to design a variable crossover with passive components that does exactly what it is supposed to.   Most plate amps on the market are absolutely horrible.   They don't work over anywhere near the range listed and their LP crossover typically interacts with the gain of the product.     In other words they suck.

Another characteristic we live with is the fact that pretty much all hardware based solutions (DSPs can change stuff in software) offer just an electrical correction.   They have don't take into account the actual acoustic output of the system (which may be rising or falling) and hence you almost never see a true 2nd order acoustic response from a subwoofer using a standard plate amp.

We are going to solve that.   Our crossover will function over the range needed as advertised and the acoustic response is going to EXACTLY match what you set on the plate amp.   And the acoustic response I'm aiming for will be a 2nd order acoustic function.    Minimizes phase shift and will provide the same response as the 4th order electrical solutions you see.

Kevin,

Is it necessary to build all of this into the plate amp? My preference is the route that M&K (and NHT, others?) have taken in that the filters are in a separate enclosure that can be placed with the rest of the system electronics.

[Kevin Haskins]

I want to point something out about the 24db (4th order) variable crossovers.    They are tough to build right.   Adire did a good job in that they had two independent 12db crossovers that didn't interact with each other.   The fact of the matter is it is very tough to design a variable crossover with passive components that does exactly what it is supposed to.   Most plate amps on the market are absolutely horrible.   They don't work over anywhere near the range listed and their LP crossover typically interacts with the gain of the product.     In other words they suck.

Another characteristic we live with is the fact that pretty much all hardware based solutions (DSPs can change stuff in software) offer just an electrical correction.   They have don't take into account the actual acoustic output of the system (which may be rising or falling) and hence you almost never see a true 2nd order acoustic response from a subwoofer using a standard plate amp.

We are going to solve that.   Our crossover will function over the range needed as advertised and the acoustic response is going to EXACTLY match what you set on the plate amp.   And the acoustic response I'm aiming for will be a 2nd order acoustic function.    Minimizes phase shift and will provide the same response as the 4th order electrical solutions you see.

Kevin,

Is it necessary to build all of this into the plate amp? My preference is the route that M&K (and NHT, others?) have taken in that the filters are in a separate enclosure that can be placed with the rest of the system electronics.

It isn't necessary but it is if you want to sell it to OEMs as a potential plate amplifier solution. 

[opnly bafld]

Can you make it both ways?