Tuning Frequency Digital design 15s

[SteveTheWelder]

I recently purchased a Pro Fab box that is made from 3/4 MDF double baffle for my 2 digital design redline 600rms 15s. I havent had a chance to get them installed yet. The box is tuned at 31Hz is that going to be too low of a tuning to listen to classic rock, and other types of music? Any input is appreciated

[Arthur79]

Hey Steve,

 

It looks like the FS for those subs is 33.6Hz, so the box is tuned lower than the sub FS (not the end of the world, but not ideal).  How big (how many cubic feet) is the box as that will have an effect on the subs performance as well.  It looks like DD says 3-6 cubic feet per sub so as long as your enclosure is at least a little over 6 cubes (to make up for driver displacement) you should be good.  Anything less than that and you probably won't be happy with their sound/output.

 

All that said, a 31Hz is pretty low.  The box will play lower tracks like rap, dubstep, bass boosted tracks etc. with more output/energy/control than music with higher frequency bass elements.

 

Not all classic rock is created equal (sonicly speaking).  As an example, there are Pink Floyd tracks that will sound great with stronger lows, but something like Led Zeppelin won't benefit from the 15s tuned to 31Hz as much (only my opinion, everybody's listening tastes are different).

 

Getting a strong set of mid-bass speakers up in the front of the cab with some clean amplification will  do more to bring out the Zeppelin.

 

Make sure you run your bass knob and don't be afraid to play with it when you are listening to different genres of music. 

 

Try not to set the low pass filter on those 15s too high.  Referencing the manual for the SMD CC1 (crossover calibrator tool), the recommended starting place for a 15 is 63Hz at 12db/octave or 80Hz at 24db/octave.  If your amp has a subsonic/infrasonic filter, set it just below the box tuning frequency if it's at 12db/octave (so maybe 30Hz) and set it a 1/2 octave below box tuning if it's at 24db/octave (so maybe 16, though I think most filters start at 20Hz).

 

I hope this helps!

[SteveTheWelder]

14 hours ago, Arthur79 said:

Hey Steve,

 

It looks like the FS for those subs is 33.6Hz, so the box is tuned lower than the sub FS (not the end of the world, but not ideal).  How big (how many cubic feet) is the box as that will have an effect on the subs performance as well.  It looks like DD says 3-6 cubic feet per sub so as long as your enclosure is at least a little over 6 cubes (to make up for driver displacement) you should be good.  Anything less than that and you probably won't be happy with their sound/output.

 

All that said, a 31Hz is pretty low.  The box will play lower tracks like rap, dubstep, bass boosted tracks etc. with more output/energy/control than music with higher frequency bass elements.

 

Not all classic rock is created equal (sonicly speaking).  As an example, there are Pink Floyd tracks that will sound great with stronger lows, but something like Led Zeppelin won't benefit from the 15s tuned to 31Hz as much (only my opinion, everybody's listening tastes are different).

 

Getting a strong set of mid-bass speakers up in the front of the cab with some clean amplification will  do more to bring out the Zeppelin.

 

Make sure you run your bass knob and don't be afraid to play with it when you are listening to different genres of music. 

 

Try not to set the low pass filter on those 15s too high.  Referencing the manual for the SMD CC1 (crossover calibrator tool), the recommended starting place for a 15 is 63Hz at 12db/octave or 80Hz at 24db/octave.  If your amp has a subsonic/infrasonic filter, set it just below the box tuning frequency if it's at 12db/octave (so maybe 30Hz) and set it a 1/2 octave below box tuning if it's at 24db/octave (so maybe 16, though I think most filters start at 20Hz).

 

I hope this helps!

Yeah, that helps out. Thank you. The enclosure says 6.58 cubic ft after displacement. 

[SteveTheWelder]

The car its going into is a 2018 impala. It has factory bose which already sound pretty good IMO. I also purchased a JL audio fix 86 processor and a JP 23 4 channel amp to power the factory bose. 

[Arthur79]

8 minutes ago, SteveTheWelder said:

Yeah, that helps out. Thank you. The enclosure says 6.58 cubic ft after displacement. 

You should be in pretty good shape there.  Since the enclosure is on the smaller side of the recommended size, you should actually see better cone control which will help keep the response tighter for classic rock tracks.  If you feel like it's not giving you as much low end extension you can always put the subs in a bigger box.

[Arthur79]

9 minutes ago, SteveTheWelder said:

The car its going into is a 2018 impala. It has factory bose which already sound pretty good IMO. I also purchased a JL audio fix 86 processor and a JP 23 4 channel amp to power the factory bose. 

That JP234 amplifier is one sexy looking piece of kit.  It also looks like a hell of a powerhouse.  I've had some factory Bose systems over the years and most of them did sound pretty good.  My only concern is that with the power that D4S amp puts out, you run a pretty high risk of cooking the factory mids and highs.  I've seen people get away with 50w RMS per channel amps on Bose or H&K setups, but I've never seen anyone put 200w+ RMS on them.  It can be hard to find mids and highs rated for that kind of wattage unless you are going the pro audio / SPL comp stuff.  I would definitely recommend dialing it back pretty far and maybe start looking at some upgrades for the front stage.

 

I've heard lots of good things about the JL fix processors but I've not used one personally.

 

Excited to hear how everything turns out, there is a showoff thread here where you can document/show off your ride if you want.

[SteveTheWelder]

1 hour ago, Arthur79 said:

That JP234 amplifier is one sexy looking piece of kit.  It also looks like a hell of a powerhouse.  I've had some factory Bose systems over the years and most of them did sound pretty good.  My only concern is that with the power that D4S amp puts out, you run a pretty high risk of cooking the factory mids and highs.  I've seen people get away with 50w RMS per channel amps on Bose or H&K setups, but I've never seen anyone put 200w+ RMS on them.  It can be hard to find mids and highs rated for that kind of wattage unless you are going the pro audio / SPL comp stuff.  I would definitely recommend dialing it back pretty far and maybe start looking at some upgrades for the front stage.

 

I've heard lots of good things about the JL fix processors but I've not used one personally.

 

Excited to hear how everything turns out, there is a showoff thread here where you can document/show off your ride if you want.

Yeah i figured if I kept the gain dialed way back, I'd probably be alright. I wouldnt mind changing out the mids and highs but will 10 or 11 speakers its going to get pricey. If I start blowing mids and highs with the gain low, I'll have to replace them lol. The JP 23.4 came in about an hour ago. It looks like a solid amp, looks nice. Thanks for the responses man, appreciate it.

[SteveTheWelder]

1 hour ago, Arthur79 said:

That JP234 amplifier is one sexy looking piece of kit.  It also looks like a hell of a powerhouse.  I've had some factory Bose systems over the years and most of them did sound pretty good.  My only concern is that with the power that D4S amp puts out, you run a pretty high risk of cooking the factory mids and highs.  I've seen people get away with 50w RMS per channel amps on Bose or H&K setups, but I've never seen anyone put 200w+ RMS on them.  It can be hard to find mids and highs rated for that kind of wattage unless you are going the pro audio / SPL comp stuff.  I would definitely recommend dialing it back pretty far and maybe start looking at some upgrades for the front stage.

 

I've heard lots of good things about the JL fix processors but I've not used one personally.

 

Excited to hear how everything turns out, there is a showoff thread here where you can document/show off your ride if you want.

Even with 11 speakers its a bit much?

[Arthur79]

21 minutes ago, SteveTheWelder said:

Yeah i figured if I kept the gain dialed way back, I'd probably be alright. I wouldnt mind changing out the mids and highs but will 10 or 11 speakers its going to get pricey. If I start blowing mids and highs with the gain low, I'll have to replace them lol. The JP 23.4 came in about an hour ago. It looks like a solid amp, looks nice. Thanks for the responses man, appreciate it.

 

Would love to see some pics of that amp out in the wild, it's always cooler IMO than the stock pics on a store site.  Does the acrylic back plate come with the protective wrap, just curious.

 

3 minutes ago, SteveTheWelder said:

Even with 11 speakers its a bit much?

 

The hard part is trying to drive all 11 speakers off a 4-channel amp.  You could probably figure out how to get all the stock front stage wired to a reasonable impedance (4Ω or close would be best for trying to split the power, if you got closer to 2Ω you are pulling significantly more power out of the amp) but getting it tuned much less being able to image it would be a nightmare I would think.  I'm not familiar with the Impala's Boes setup, but I would imagine its a mix of larger mid-bass drivers like 6.5"s, 3.5 or 4" mids and tweets (not to mention whatever they have in for the center channel).  So figuring how to set crossover points trying to drive all the speakers from a 4 channel source is the first challenge.  Let's say you  used 1 channel for the 6.5" speakers, 1 channel for the 3.5-4" mids, 1 channel for tweets and maybe the last channel for the center channel (all hypothetical but common factory upgraded sound systems) figuring out how to even manage fade and balance are out the window, you would be using them to try and do some really primitive EQing.  Time alignment goes out the window as well.

 

It would be one hell of an interesting science project, but I don't know if you would be able to get the sound you're looking for.

 

What a lot of people in the SQ world do is delete the center channel as well as the rear stage and focus on running an active front stage (2 or 3 way).  If you're not worried about rear fill, you could run a 2-way active setup in the front and you would be surprised how well you can image the sound stage using time alignment in your DSP.  You also have a lot of flexibility tuning the EQ to massage the different frequency bands in a way that work best for your car.

 

If you have people in the back or just like rear fill, you could run a 2 or 3 way passive setup in the front and coaxials in the back and you should still be able to get some pretty good imaging with that FIX DSP.

 

Dean over at Five Star Car Audio on YouTube did a video recently where they did something similar to that, I can try to find the video if you would be interested in checking it out.

 

[SteveTheWelder]

2 hours ago, Arthur79 said:

 

Would love to see some pics of that amp out in the wild, it's always cooler IMO than the stock pics on a store site.  Does the acrylic back plate come with the protective wrap, just curious.

 

 

The hard part is trying to drive all 11 speakers off a 4-channel amp.  You could probably figure out how to get all the stock front stage wired to a reasonable impedance (4Ω or close would be best for trying to split the power, if you got closer to 2Ω you are pulling significantly more power out of the amp) but getting it tuned much less being able to image it would be a nightmare I would think.  I'm not familiar with the Impala's Boes setup, but I would imagine its a mix of larger mid-bass drivers like 6.5"s, 3.5 or 4" mids and tweets (not to mention whatever they have in for the center channel).  So figuring how to set crossover points trying to drive all the speakers from a 4 channel source is the first challenge.  Let's say you  used 1 channel for the 6.5" speakers, 1 channel for the 3.5-4" mids, 1 channel for tweets and maybe the last channel for the center channel (all hypothetical but common factory upgraded sound systems) figuring out how to even manage fade and balance are out the window, you would be using them to try and do some really primitive EQing.  Time alignment goes out the window as well.

 

It would be one hell of an interesting science project, but I don't know if you would be able to get the sound you're looking for.

 

What a lot of people in the SQ world do is delete the center channel as well as the rear stage and focus on running an active front stage (2 or 3 way).  If you're not worried about rear fill, you could run a 2-way active setup in the front and you would be surprised how well you can image the sound stage using time alignment in your DSP.  You also have a lot of flexibility tuning the EQ to massage the different frequency bands in a way that work best for your car.

 

If you have people in the back or just like rear fill, you could run a 2 or 3 way passive setup in the front and coaxials in the back and you should still be able to get some pretty good imaging with that FIX DSP.

 

Dean over at Five Star Car Audio on YouTube did a video recently where they did something similar to that, I can try to find the video if you would be interested in checking it out.

 

Yeah, I really don't know much about setting the processor up, or how they would hook up to the factory bose, there's a shop in town that I've heard good things about, I'm going to let them deal with that part and maybe make some adjustments after. I can send you some pics of the JP amp when I get off work if youd like.