Getting a smooth bass transition from speakers to sub.

jliedeka

jliedeka

Audioholic General
If we knew the internal volume of the box and length and diameter of the port, someone could check a box simulator and see how that would behave. I use WinISD which is free. It lets you mess around with the tuning and see the predicted response.

Jim
 
Y

yepimonfire

Audioholic Samurai
lets just say according to the box calculator, your going to need a bigger box for the driver, your going to get around 50hz -3db of response, with a bad curve at 100 giving you boomy bass. give me the ports diameter and i can give a better calculation.
 
F

FuzzyReets

Audioholic
Can anyone give me average responses for speakers and subs. I'm trying to understand this stuff. I'm reading that the shitty polk sub I have has a frequency response of 24hz to 40hz and I'm reading the Dayton's I have have a frequency response of 19hz to 1000hz. So I get that it can handle lower signals because 19 is lower than 24 from the sub. I get that. So I found teh official specs for my Boston HD7s and those say the frequency response is 52-20000hz!!! I feel like I'm missing something important about these specifications because that doesn't make sense to me. If someone can fill in the blanks I'd appreciate it. Thanks.

Also the Boston's say the crossover frequency is 3000hz???? I'm confused now :(
 
j_garcia

j_garcia

Audioholic Jedi
I think the real thing here is that those mains will likely play low enough that the sub isn't really benefitting here. That does mean however, that the receiver is now having to handle the lows rather than the external amp in the sub, so your receiver has to work a lot harder. If the receiver can handle it, in this case, I think it would be a better way to set this system up. Normally, like with a better sub, I would recommend the opposite because a well designed sub will handle the lows while offloading that power draw from the receiver.
 
MidnightSensi

MidnightSensi

Audioholic Samurai
Can anyone give me average responses for speakers and subs. I'm trying to understand this stuff. I'm reading that the shitty polk sub I have has a frequency response of 24hz to 40hz and I'm reading the Dayton's I have have a frequency response of 19hz to 1000hz. So I get that it can handle lower signals because 19 is lower than 24 from the sub. I get that. So I found teh official specs for my Boston HD7s and those say the frequency response is 52-20000hz!!! I feel like I'm missing something important about these specifications because that doesn't make sense to me. If someone can fill in the blanks I'd appreciate it. Thanks.

Also the Boston's say the crossover frequency is 3000hz???? I'm confused now :(

The 3000Hz frequency is the midrange to tweeter crossover frequency, not where to cross them over on the bottom end.

Regarding the phase comments earlier: phase knobs are a little misleading, because phase changes with frequency. So you can get the subwoofer (nearly) in phase with the mains at the crossover frequency. Really the distance setting on your receiver will do the same thing, and can actually advance timing (which is what is needed for a subwoofer, generally) by delaying the mains.
 
F

FuzzyReets

Audioholic
TLS Guy

TLS Guy

Audioholic Jedi
What about Axiom EP175 v2? http://www.axiomaudio.com/ep175.html My buddy has these and loves their stuff. Still need to know what specs you're looking at to recommend such things. Thanks.
Before you think about getting a sub you need to scrap your Pioneer mains.

You can't swap drivers.

Your speakers are old eighties Japanese speakers, that never were any good.

They used paper coned speakers of higher sensitivity than your Dayton replacements. So you now have far too much mid and high range.

The next issue is that all drivers have unique Thiel/Small parameters and have to be precisely matched to box volume and have to be ported correctly.

The original speakers would have to be tuned to a much higher frequency than your Daytons.

Your new woofers require a box volume of 4 cu.ft, plus driver volume, bracing and port volume. Your box is grossly under ported. Your Dayton driver requires a large slot vent to produce any decent bass without port compression. Here is the correct alignment for your current driver.

Name: Dayton ST385-8 15" Series II W
Type: Standard one-way driver
Company: Dayton Loudspeaker Co.
No. of Drivers = 1
Fs = 19 Hz
Qms = 8.3
Vas = 301 liters
Cms = 0.216 mm/N
Mms = 324.4 g
Rms = 4.665 kg/s
Xmax = 7.9 mm
Xmech = 11.85 mm
P-Dia = 355 mm
Sd = 989.8 sq.cm
P-Vd = 0.782 liters
Qes = 0.33
Re = 5.8 ohms
Le = 4.25 mH
Z = 8 ohms
BL = 26.09 Tm
Pe = 300 watts
Qts = 0.32
no = 0.603 %
1-W SPL = 89.8 dB
2.83-V SPL = 91.35 dB
-----------------------------------------
Box Properties
Name:
Type: Vented Box
Shape: Prism, square
Vb = 3.984 cu.ft
Fb = 22.01 Hz
QL = 6.353
F3 = 31.2 Hz
Fill = minimal
No. of Vents = 1
Vent shape = rectangle
Vent ends = two flush
Hv = 3 in
Wv = 7 in
Lv = 25.62 in


The lowest that driver can hit is 31 Hz and not 19 Hz. 19 Hz is the free air resonance of the driver, not its maximal bass extension.

In you box I doubt the driver reproduces much below 100 Hz.

So you have a total mess you need to sort out, before thinking about a subwoofer.
 
F

FuzzyReets

Audioholic
Before you think about getting a sub you need to scrap your Pioneer mains.

You can't swap drivers.

Your speakers are old eighties Japanese speakers, that never were any good.

They used paper coned speakers of higher sensitivity than your Dayton replacements. So you now have far too much mid and high range.

The next issue is that all drivers have unique Thiel/Small parameters and have to be precisely matched to box volume and have to be ported correctly.

The original speakers would have to be tuned to a much higher frequency than your Daytons.

Your new woofers require a box volume of 4 cu.ft, plus driver volume, bracing and port volume. Your box is grossly under ported. Your Dayton driver requires a large slot vent to produce any decent bass without port compression. Here is the correct alignment for your current driver.

Name: Dayton ST385-8 15" Series II W
Type: Standard one-way driver
Company: Dayton Loudspeaker Co.
No. of Drivers = 1
Fs = 19 Hz
Qms = 8.3
Vas = 301 liters
Cms = 0.216 mm/N
Mms = 324.4 g
Rms = 4.665 kg/s
Xmax = 7.9 mm
Xmech = 11.85 mm
P-Dia = 355 mm
Sd = 989.8 sq.cm
P-Vd = 0.782 liters
Qes = 0.33
Re = 5.8 ohms
Le = 4.25 mH
Z = 8 ohms
BL = 26.09 Tm
Pe = 300 watts
Qts = 0.32
no = 0.603 %
1-W SPL = 89.8 dB
2.83-V SPL = 91.35 dB
-----------------------------------------
Box Properties
Name:
Type: Vented Box
Shape: Prism, square
Vb = 3.984 cu.ft
Fb = 22.01 Hz
QL = 6.353
F3 = 31.2 Hz
Fill = minimal
No. of Vents = 1
Vent shape = rectangle
Vent ends = two flush
Hv = 3 in
Wv = 7 in
Lv = 25.62 in


The lowest that driver can hit is 31 Hz and not 19 Hz. 19 Hz is the free air resonance of the driver, not its maximal bass extension.

In you box I doubt the driver reproduces much below 100 Hz.

So you have a total mess you need to sort out, before thinking about a subwoofer.
Interesting. Can I drill holes in my current Pioneers to port them properly? Is there a way to test how low they are going with an SPL Meter? Buying all that stuff is not an option right now unfortunately.
 
TLS Guy

TLS Guy

Audioholic Jedi
Interesting. Can I drill holes in my current Pioneers to port them properly? Is there a way to test how low they are going with an SPL Meter? Buying all that stuff is not an option right now unfortunately.
You have a lot more issues than porting.

First I need to know the volume of the woofer enclosure. Then I can see if you could use more ports. However that driver since it has fairly good bass extension and is large, requires a large long port. The port for a 4 cu. ft box is 25.6" long.

The other issue is matching the unit to the mids and highs. Your old paper coned woofer, is a very different animal to the heavier cone of the Dayton. Whenever you change drivers crossover changes always have to occur, as not only are a drivers Thiel/Small parameters unique, but so are the acoustic parameters.

So I would bet that a lot of your problem is due to different acoustic output of your driver from the old one.

The fact is that modifying a speaker is more trouble and more difficult than building one from scratch.

May be you should consider building a new set of speakers round those Daytons.

If you have the old drivers, then put them back.
 
F

FuzzyReets

Audioholic
You have a lot more issues than porting.

First I need to know the volume of the woofer enclosure. Then I can see if you could use more ports. However that driver since it has fairly good bass extension and is large, requires a large long port. The port for a 4 cu. ft box is 25.6" long.

The other issue is matching the unit to the mids and highs. Your old paper coned woofer, is a very different animal to the heavier cone of the Dayton. Whenever you change drivers crossover changes always have to occur, as not only are a drivers Thiel/Small parameters unique, but so are the acoustic parameters.

So I would bet that a lot of your problem is due to different acoustic output of your driver from the old one.

The fact is that modifying a speaker is more trouble and more difficult than building one from scratch.

May be you should consider building a new set of speakers round those Daytons.

If you have the old drivers, then put them back.
Yeah I have read that others have built speakers from scratch with those Daytons. How would I go about doing that? Can you point me in the right direction? Thanks for all your input.
 
Y

yepimonfire

Audioholic Samurai
go to ajdesigner.com and download a box calculator, you put the woofers parameters into the thing and calculate it, qtc is a self added parameter, the lower it is the longer the bass extension is but if you put it too low, it will ask you to build a box that isnt physically possible (like -8ft wide etc.) start with 1.0 and go up or down depending on preference and keep checking "Vb" to make sure you dont have a negative parameter. when you have what you want click on "box calculator" and it will tell you the best dimensions to build the cabinet for. mid-ranges and tweeters normally do not need to be calculated because they for one they are going into the same box as the woofer and two the box volume usually only affect the lower frequencies. next step would be crossovers. these are simple devices parts-express.com has pre-made the make sure the woofer gets the low end, and the tweeter gets the high end, you should check what the lowest freq. response is of your tweeter and cross it over a bit higher then that, 3,000hz is a good starting place though. you will need something to drill a hole into the cabinets obviously to the cut-out diameter of the drivers, then you will want to damp it is much as physically possible using poly-fill type material or yellow fiberglass (the pink doesnt work as good) you will need to get the correct type of speaker cables to hook the drivers up to the crossover and the wires will have to be soldered to the x-over. you will have to find some way to mount the x-over but that shouldnt be hard. if your designing a ported cabinet, which a ported one will give you an extra 10-50hz of response, you cannot just slap some random tube in the cabinet, they have to be a certain length to diameter ratio which is determined by the tuning freq. of both the box and driver. you will apparently have to put some binding posts into the cabinet and then connect those to the input of the x-over, that part shouldnt be too hard to figure out. building speakers for the most part are pretty simple but its always important you have the right cabinet dimensions for your driver and the right x-over points, like you wouldnt want to x-over a tweeter at 1000 hz, for one it wouldnt be able to reproduce it correctly, two you run the risk of destroying the tweeter. if you have a tweeter with a response down to 2,500 hz and a woofer with a response up to 5000hz, you would want to crossover at about 3khz. if you have a woofer with a response up to 1khz and a tweeter down to 2,500, you will either need a different driver or design a 3-way which requires 3 x-over points, and instead of a tweeter and woofer, and tweeter, midrange driver, and woofer. imo these sound far superior to 2-ways, but may be a bit more complicated to design.


and to j_garcia, apparently i was wrong and that only happened to me one time when running a particular drive through the calculator and i guess i based my idea on that. my apologies.
 
F

FuzzyReets

Audioholic
Could anyone point me in the right direction that would show me how I could test to see how my overall system is working? I've been reading about using test tones and measuring with my SPL meter but I really don't understand how/what to do with it. Thanks.
 
TLS Guy

TLS Guy

Audioholic Jedi
Yeah I have read that others have built speakers from scratch with those Daytons. How would I go about doing that? Can you point me in the right direction? Thanks for all your input.
I have had a chance to look at your situation now. Unfortunately you have picked a woofer that is very hard to work with
.

If you look at the acoustic data, (and by the way the data below 200 Hz in not reliable,) the response gets very ragged at 500 Hz. The biggest problem is a huge 12db break up mode peak at 1200 Hz.

I'm certain the crossover in your Pioneer speakers is well above where the ragged response starts. Also all those types of speakers had low order crossovers. So I'm sure when you are listening to your speakers, the sound is totally dominated by that 1200 Hz peak.

This makes this a difficult project and not cheap.

There are going to be a lot of expensive components in the crossover. At a guess I suspect parts will run around $400.

This design requires a fourth order crossover around 350 Hz which is a formidable construction. That peak will likely still need a notch filter.

Since the crossover has to be so low, there will be a lot of power handed to the mid range drivers and two mid range drivers will be required per speaker. I would recommend these.

For the tweeters these.

The other problem with that woofer is that it requires a large box and port. When you add bracing, drivers, the mid range enclosure, crossover volume, the total box volume is going to end up around 6 cu.ft, and be a formidable construction project.

In many ways it would be best to use a separate amps for woofer and and the mid/HF section, in other words biamp it with electronic crossover.

That would only be possible if your receiver has pre outs.

If your budget is tight, I would abandon those drivers and go on to something more practical. This is a formidable design challenge.

There is no quick fix for your problem because of the 1200 Hz peak. What this amounts to is that a narrow band around 1200 Hz is playing more than twice as loud as everything else. That must sound bad. Only a comprehensive design solution will solve it and that will be complex, expensive and a lot of effort.
 
E

emrliquidlife

Junior Audioholic
Where are you located? I'm selling some sets of speakers.

Ed
 
newsletter

  • RBHsound.com
  • BlueJeansCable.com
  • SVS Sound Subwoofers
  • Experience the Martin Logan Montis
Top