I'm trying to achieve high efficiency and good bass for low power amp.
Will the below speaker choices work? My goals include good bass, more volume without turning the knob as far, clean/clear soundstage, and good imaging and instrument seperation. It will run on my pair of LM3875 Peter Daniels kit I built a few years ago. I can't remember exactly, but with the P/S I chose I think it's close to 40 watts per channel and needs an 8 ohm speaker.
Tweeter: Fostex FT17H
8 Ohm, 98.5dB
Crossover to play at 7500Hz and higher
http://www.madisound.com/loudspeaker_specifications/ft17h.pdf
Mid: Audax PR170M0 6.5" Midrange 100dB
cross to play from 250Hz to 7500Hz
Will be in sealed 0.2 cu. ft. (F3 190)
https://www.madisoundspeakerstore.com/pro-sound/audax-pr170m0-6.5-midrange-100db/
Bass: Goldwood GW-1558
8 ohm, 95.6 dB
Crossed to play 250Hz and lower
Will be in a huge 34.6 cu ft (less displacement of .2 cu ft sealed mid box) net 34.4 cu ft vented box (f3 22Hz)
Goldwood GW-1558 15" Pro Woofer
Will the below speaker choices work? My goals include good bass, more volume without turning the knob as far, clean/clear soundstage, and good imaging and instrument seperation. It will run on my pair of LM3875 Peter Daniels kit I built a few years ago. I can't remember exactly, but with the P/S I chose I think it's close to 40 watts per channel and needs an 8 ohm speaker.
Tweeter: Fostex FT17H
8 Ohm, 98.5dB
Crossover to play at 7500Hz and higher
http://www.madisound.com/loudspeaker_specifications/ft17h.pdf
Mid: Audax PR170M0 6.5" Midrange 100dB
cross to play from 250Hz to 7500Hz
Will be in sealed 0.2 cu. ft. (F3 190)
https://www.madisoundspeakerstore.com/pro-sound/audax-pr170m0-6.5-midrange-100db/
Bass: Goldwood GW-1558
8 ohm, 95.6 dB
Crossed to play 250Hz and lower
Will be in a huge 34.6 cu ft (less displacement of .2 cu ft sealed mid box) net 34.4 cu ft vented box (f3 22Hz)
Goldwood GW-1558 15" Pro Woofer
you need to have tweeter that can play lower than that.
if its going to be passive vented bass, max sensitivity will be around 94db max (in general for a suitable woofer in a suitable box), unless you loaded it in a horn enclosure.
when you design speakers, the physical distance between midrange and tweeter will dictate your transfer function, so it will be below 4khz if you want to get the right summation between them and seamless sound.
simulate your selected bass driver to make sure you can get your target sensitivity.
the midrange can be 2db lower than the tweeter and/or woofer, and whichever has lowest sensitivity will be your final sensitivity (woofer (in your cab alignment), mid and tweeter)
if its going to be passive vented bass, max sensitivity will be around 94db max (in general for a suitable woofer in a suitable box), unless you loaded it in a horn enclosure.
when you design speakers, the physical distance between midrange and tweeter will dictate your transfer function, so it will be below 4khz if you want to get the right summation between them and seamless sound.
simulate your selected bass driver to make sure you can get your target sensitivity.
the midrange can be 2db lower than the tweeter and/or woofer, and whichever has lowest sensitivity will be your final sensitivity (woofer (in your cab alignment), mid and tweeter)
Thanks for reply. I thought the tweeter might be too high. So you're saying it just doesn't come low enough in frequency to match the mid I chose, and if I find a tweeter that will play 4k or lower then it will sum with the mid I chose? Or are you saying something else about 4k that doesn't have to do with the mid I chose?
When you say: simulate your selected bass driver to make sure you can get your target sensitivity.
Is the graph here what you mean by simulate?
http://www.goldwoodsound.com/Woofers1_files/GW1558graphs.pdf
If so, what do you think, and if not, how do I simulate?
Thanks,
When you say: simulate your selected bass driver to make sure you can get your target sensitivity.
Is the graph here what you mean by simulate?
http://www.goldwoodsound.com/Woofers1_files/GW1558graphs.pdf
If so, what do you think, and if not, how do I simulate?
Thanks,
The bass transducer: the manufacturer says that it is designed for all uses except hi-fi - it isn't mentioned ! 
And it is too big! You could replace Sd to excursion, so maybe a 10"
and could gain some dB/SPL by using a 4 Ω speaker ( so maybe... a car speaker ).
The Audax mid works well also with 1st order crossover, about 33uF and 0.5 mH. It's low excursion makes it unsuitable for a 250 Hz crossover point until 4th order is considered...
I used it with an Audax titanium dome 94 dB/W/m; also silk dome making 96 dB is available, though they both don't have ferrofluid.
And it is too big! You could replace Sd to excursion, so maybe a 10"
and could gain some dB/SPL by using a 4 Ω speaker ( so maybe... a car speaker ).
The Audax mid works well also with 1st order crossover, about 33uF and 0.5 mH. It's low excursion makes it unsuitable for a 250 Hz crossover point until 4th order is considered...
I used it with an Audax titanium dome 94 dB/W/m; also silk dome making 96 dB is available, though they both don't have ferrofluid.
------------As others have noted-----------
The Fostex requires a Xover over 5Khz.
The Audax PR170M0 cone craps-out around 3Khz from resonance and beaming.
The Goldwood GW-1558 has Qts=0.63, and is best suited for dipole operation. It and was probably designed for open back guitar amps.
---------------
Since you are willing to accept a 34.4 cu ft vented box, take a look at the 9cuft Maximus_18 kit coming soon from diysoundgroup.com. 97db @2.83V sensitivity
Maximus-18 DIY Sound Group
Maximus-18 DIY Sound Group
Price Break Down:
1- 18" woofer ~$220 for Peavey LoRide18
1- 12" Eminence Deltalite woofer: $134.99
1- Denovo FL-450: $142
1- SEOS-15 waveguide: $35
1- Set of crossover parts: $TBA
The Fostex requires a Xover over 5Khz.
The Audax PR170M0 cone craps-out around 3Khz from resonance and beaming.
The Goldwood GW-1558 has Qts=0.63, and is best suited for dipole operation. It and was probably designed for open back guitar amps.
---------------
Since you are willing to accept a 34.4 cu ft vented box, take a look at the 9cuft Maximus_18 kit coming soon from diysoundgroup.com. 97db @2.83V sensitivity
Maximus-18 DIY Sound Group
Maximus-18 DIY Sound Group
Price Break Down:
1- 18" woofer ~$220 for Peavey LoRide18
1- 12" Eminence Deltalite woofer: $134.99
1- Denovo FL-450: $142
1- SEOS-15 waveguide: $35
1- Set of crossover parts: $TBA
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A crossover at 4.5Khz with the PR170M0 to a dome tweeter as in the XS-96 will have noticable lobing... both large changes in SPL sitting vs. standing, and also changes in perceived volume around the Xover frequency as the percentage of direct listener SPL vs. indirect room SPL changes. Lobes push more sound energy down(floor_bounce) and up(ceiling_bounce) and those reflections change the sound stage.
Also, the polar response of the Audax PR170M0 must be closely matched to the polar response of the tweeter around the Xover frequency to maintain a smooth directivity function, for both uniform SPL and consistent room reflections(sound stage).
The promise of powerful dynamics with excellent low level details from a high efficiency speaker creates challenges. The "good" sometimes overshadows the "nasty" in some modest cost/size high efficiency designs.
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I'd go for the biggest compression driver you can get, and a 15" driver below it.
Fewer drivers on the same budget means each driver is of better quality. For instance, I really like my Beyma 15P1200Nd + EV DH1a 2-ways. I use them for PA duties, but they're also perfectly at home in a HiFi situation.
You could use 3 cu.ft for the bass drivers and achieve respectably low bass, though an f3 of 22Hz might be pushing it. I can say, though, that the high-end pro 15"s are worth the extra.
Chris
Fewer drivers on the same budget means each driver is of better quality. For instance, I really like my Beyma 15P1200Nd + EV DH1a 2-ways. I use them for PA duties, but they're also perfectly at home in a HiFi situation.
You could use 3 cu.ft for the bass drivers and achieve respectably low bass, though an f3 of 22Hz might be pushing it. I can say, though, that the high-end pro 15"s are worth the extra.
Chris
I would not attempt a vented box for a driver with a Q=0.63.
That is either sealed box, or open baffle, or even infinite baffle. Maybe a little bit of LT to adjust the box Q and the F-3dB
But with a 3.9mm Xmax you will need a low bass speaker making it a 4way if you want/need low bass reproduction.
That is either sealed box, or open baffle, or even infinite baffle. Maybe a little bit of LT to adjust the box Q and the F-3dB
But with a 3.9mm Xmax you will need a low bass speaker making it a 4way if you want/need low bass reproduction.
Hi,
Considering the combo PR170 M0 / Audax tweeter you can have a look at the Pro 33 Kit from Audax, cf shematics. The discontinuited PR 130 has been replaced with success with Fostex FT17H, see crossover shematics.
But it's an almost 25 years old design
Considering the combo PR170 M0 / Audax tweeter you can have a look at the Pro 33 Kit from Audax, cf shematics. The discontinuited PR 130 has been replaced with success with Fostex FT17H, see crossover shematics.
But it's an almost 25 years old design
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Hey Linesource, you "americans" are so "biiiiig " !
You wrote:
1- 18" woofer ~$220 for Peavey LoRide18
1- 12" Eminence Deltalite woofer: $134.99
1- Denovo FL-450: $142
1- SEOS-15 waveguide: $35
1- Set of crossover parts: $TBA
My actual system is:
1 - seas RCY12 aluminum cone 4" woofer -60 $
1 - aurasound NSW2-326-8AT 2" midrange 23 $ -now 19 $
1- dayton amt mini-8 -29 $
1- set of crossover 40 $ with polypropilene 80 $
You wrote:
1- 18" woofer ~$220 for Peavey LoRide18
1- 12" Eminence Deltalite woofer: $134.99
1- Denovo FL-450: $142
1- SEOS-15 waveguide: $35
1- Set of crossover parts: $TBA
My actual system is:
1 - seas RCY12 aluminum cone 4" woofer -60 $
1 - aurasound NSW2-326-8AT 2" midrange 23 $ -now 19 $
1- dayton amt mini-8 -29 $
1- set of crossover 40 $ with polypropilene 80 $
The Audax TW025 series, especially the 96 dB/W/m silk dome should match perfectly with the MO.
The PR17 MO still gives fantastic and rich vocals.
Not sure why you would put a gigantic woofer in your room or use horns and CDs
I must be doing something wrong
Thank you all for the help / suggestions.
I think I must be doing something wrong though, maybe you can help. I'm trying to use a computer model software. It's Jeff Bagby's MS Excel sheet, Woofer Box and Circuit Designer 5.0
I inputed the T/S parameters for the Audax PR240M0. It is described as a 10" 95 SPL "Midrange" speaker, which has a substantially flat response from 100 Hz to 2KHz.
https://www.madisoundspeakerstore.com/pro-sound/audax-pr240m0-professional-10-woofer/
So on the computer model, I found that if I put it in a huge box (6.5 feet tall, 15 inch wide, 18 inch deep / 278.59 liters or 9.84 cubic feet) with two vents (2.5" dia. X 3" long) -that it will play loud, and really low.
F3 of 24.4 Hz with an SPL of around 92dB with 1 watt!!
Can that be real, or am I doing something wrong?
If it would work, in that alignment will it still play flat up to 2kHz? I think I must be missing something.
If it will work, then I could find a good tweeter that will come down that far and just make it a two way.
I did look at your suggestions above, and if my idea here won't work, then I'll have to look at those more. I don't want to ignore good advise, it's just that this looks a little less expensive.
-AlexQS
Thank you all for the help / suggestions.
I think I must be doing something wrong though, maybe you can help. I'm trying to use a computer model software. It's Jeff Bagby's MS Excel sheet, Woofer Box and Circuit Designer 5.0
I inputed the T/S parameters for the Audax PR240M0. It is described as a 10" 95 SPL "Midrange" speaker, which has a substantially flat response from 100 Hz to 2KHz.
https://www.madisoundspeakerstore.com/pro-sound/audax-pr240m0-professional-10-woofer/
So on the computer model, I found that if I put it in a huge box (6.5 feet tall, 15 inch wide, 18 inch deep / 278.59 liters or 9.84 cubic feet) with two vents (2.5" dia. X 3" long) -that it will play loud, and really low.
F3 of 24.4 Hz with an SPL of around 92dB with 1 watt!!
Can that be real, or am I doing something wrong?
If it would work, in that alignment will it still play flat up to 2kHz? I think I must be missing something.
If it will work, then I could find a good tweeter that will come down that far and just make it a two way.
I did look at your suggestions above, and if my idea here won't work, then I'll have to look at those more. I don't want to ignore good advise, it's just that this looks a little less expensive.
-AlexQS
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winisd pro will give you cone excursion.
tuning a high efficiency mid range speaker to reproduce low frequencies will usually result in exceeding Xmax at tiny input powers/input voltage.
High efficiency is often gained by significantly reducing moving mass. That means thin cones and short coils. Both limit the usable bandwidth.
tuning a high efficiency mid range speaker to reproduce low frequencies will usually result in exceeding Xmax at tiny input powers/input voltage.
High efficiency is often gained by significantly reducing moving mass. That means thin cones and short coils. Both limit the usable bandwidth.
Group delay and filters
Thanks Henry. I think I see now why a midrange speaker would not work as a subwoofer.
I've been modeling a peavey that someone above mentioned.
Cone excursion can exceed xmax easily around 20Hz with 150watts. However my amp only puts out 40, maybe peak 100.
Is there much to worry about way down there though?
Also, if I put in a hi-pass 4th order at 18Hz it keeps cone excursion well under xmax.
Regarding Group Delay, from what I read, it seems that around 1000k is the critical area. One said 1.6mm at 1000Hz is a common/normal result from filters. It also mentioned the 100Hz region, 5ms vented or 2.5ms sealed is common result of bass cab tuning. I can't find anything about an acceptable GD level at lower frequencies, but I assume an ill result of percussion instruments sounding like pipe organs is possible.
When I add the 18Hz high pass filter, it also pushed the rise in GD down to lower frequencies. (The computer model had been showing 5ms at 45Hz) but with the filter in place 5ms is down at 31Hz. Aside from that, GD falls steeply to 1.0ms at 40Hz and continues to fall and flatten 0.6ms at 1000Hz.
So here's my questions:
Is the filter a good solution to control cone excursion and group delay?
Are my group delay numbers acceptable? It peaks just over 15ms just under 25Hz.
Thanks Henry. I think I see now why a midrange speaker would not work as a subwoofer.
I've been modeling a peavey that someone above mentioned.
Cone excursion can exceed xmax easily around 20Hz with 150watts. However my amp only puts out 40, maybe peak 100.
Is there much to worry about way down there though?
Also, if I put in a hi-pass 4th order at 18Hz it keeps cone excursion well under xmax.
Regarding Group Delay, from what I read, it seems that around 1000k is the critical area. One said 1.6mm at 1000Hz is a common/normal result from filters. It also mentioned the 100Hz region, 5ms vented or 2.5ms sealed is common result of bass cab tuning. I can't find anything about an acceptable GD level at lower frequencies, but I assume an ill result of percussion instruments sounding like pipe organs is possible.
When I add the 18Hz high pass filter, it also pushed the rise in GD down to lower frequencies. (The computer model had been showing 5ms at 45Hz) but with the filter in place 5ms is down at 31Hz. Aside from that, GD falls steeply to 1.0ms at 40Hz and continues to fall and flatten 0.6ms at 1000Hz.
So here's my questions:
Is the filter a good solution to control cone excursion and group delay?
Are my group delay numbers acceptable? It peaks just over 15ms just under 25Hz.
Attachments
I have a couple of more questions.By the way, Thank you much for all of the above advice.I believe it sent me on a very educational path of research, though I know I still have much to learn.
Based on my parameters/goals of needing high eff speakers that can be driven by my ~40 wpc LM3875 chip amp, I’ve landed on the Eminence Beta-12CX and EminenceASD 1001 tweeter.There are a couple of neat articles I found.One of them is from an Eminence Employee that built some stage monitors in sealed 1.21 cubic foot enclosure (36.24 liters).Here’s that article, note there are two different designs there, I’m purposing that I follow the bottom one.Also, there’s this data sheet from Eminence about Beta-12CX.On about page 7 of that pdf it has a box that Eminence suggests will work for that driver.“Beta12CX Small Sealed EnclosureBy McJerry, Eminence Speaker LLCDisplacement limited to 125 Watts. Use a 24 dB per octave high pass filter set to 100 Hz or higher.Great floor monitor. Can be used as a mid/high box if you use a sub.”
Too bad that budget limits all of my projects, but for the 100Hz – 20,000Hz range, that puts me at about $150 per channel including the passive crossover that the Eminence guys designed specifically for these above drivers.
I think I’ll just use a plate amp to drive the bottom end (Hoffman, you know...)It looks like many recommend the Dayton RSS315HFA-8 12”.By the way, I believe that I’ll be able to get a tighter bass if I stick with a sealed enclosure.I see a linkwitz-transform via miniDSP and DAC in the future, but in the meantime 100 liters looks like it will Fsc (is that the same as F3?) at 34.13Hz, Q is .699 according to WinISD.
Here’s one of my questions:Why is WinISD showing cone excursion reaching Xmax with only 125 watts?The data sheet shows something like 700watts, and I’ve read about people with 250 watts saying that you need more in a sealed enclosure for these to really shine.Need I be concerned?By the way, I doubt this would be used much if at all for home theatre, just music.
And a related question:WinISD shows that when I get to about 20 watts with the Beta 12-CX, that I’ll need 300 with the Dayton 12” to have equal SPL levels.I thought a way to take care of this is to get a 500 watt plate amp, then I won’t need to turn the gain up all the way, and if I understand right this would give me a little headroom too.I’m thinking that this would be better than putting an L-Pad on the Beta 12-CX, as this about defeats the purpose of searching for a high efficiency speaker in the first place.Does that sound right?
Last question for today:I’m thinking of putting this all into a 4 sided pyramid type sealed enclosure.Obviously with a board inside separating the mid and subwoofers airspace.I’m not too sure of whether or not the Dayton 12” would work in a downward firing position (well I know it would work, but I’m afraid it may sag over time, your thoughts or experience here is welcomed).Should I have it forward firing just under the Beta 12-CX?Will down firing the sub gain me a couple of dB?I was thinking it could do the opposite, because I have carpet.The range I’m thinking it will cover is roughly 30 – 100 or maybe up to 125Hz,..Is there much stereo imaging down there, or at that frequency does it not make a difference which way it is facing?
Based on my parameters/goals of needing high eff speakers that can be driven by my ~40 wpc LM3875 chip amp, I’ve landed on the Eminence Beta-12CX and EminenceASD 1001 tweeter.There are a couple of neat articles I found.One of them is from an Eminence Employee that built some stage monitors in sealed 1.21 cubic foot enclosure (36.24 liters).Here’s that article, note there are two different designs there, I’m purposing that I follow the bottom one.Also, there’s this data sheet from Eminence about Beta-12CX.On about page 7 of that pdf it has a box that Eminence suggests will work for that driver.“Beta12CX Small Sealed EnclosureBy McJerry, Eminence Speaker LLCDisplacement limited to 125 Watts. Use a 24 dB per octave high pass filter set to 100 Hz or higher.Great floor monitor. Can be used as a mid/high box if you use a sub.”
Too bad that budget limits all of my projects, but for the 100Hz – 20,000Hz range, that puts me at about $150 per channel including the passive crossover that the Eminence guys designed specifically for these above drivers.
I think I’ll just use a plate amp to drive the bottom end (Hoffman, you know...)It looks like many recommend the Dayton RSS315HFA-8 12”.By the way, I believe that I’ll be able to get a tighter bass if I stick with a sealed enclosure.I see a linkwitz-transform via miniDSP and DAC in the future, but in the meantime 100 liters looks like it will Fsc (is that the same as F3?) at 34.13Hz, Q is .699 according to WinISD.
Here’s one of my questions:Why is WinISD showing cone excursion reaching Xmax with only 125 watts?The data sheet shows something like 700watts, and I’ve read about people with 250 watts saying that you need more in a sealed enclosure for these to really shine.Need I be concerned?By the way, I doubt this would be used much if at all for home theatre, just music.
And a related question:WinISD shows that when I get to about 20 watts with the Beta 12-CX, that I’ll need 300 with the Dayton 12” to have equal SPL levels.I thought a way to take care of this is to get a 500 watt plate amp, then I won’t need to turn the gain up all the way, and if I understand right this would give me a little headroom too.I’m thinking that this would be better than putting an L-Pad on the Beta 12-CX, as this about defeats the purpose of searching for a high efficiency speaker in the first place.Does that sound right?
Last question for today:I’m thinking of putting this all into a 4 sided pyramid type sealed enclosure.Obviously with a board inside separating the mid and subwoofers airspace.I’m not too sure of whether or not the Dayton 12” would work in a downward firing position (well I know it would work, but I’m afraid it may sag over time, your thoughts or experience here is welcomed).Should I have it forward firing just under the Beta 12-CX?Will down firing the sub gain me a couple of dB?I was thinking it could do the opposite, because I have carpet.The range I’m thinking it will cover is roughly 30 – 100 or maybe up to 125Hz,..Is there much stereo imaging down there, or at that frequency does it not make a difference which way it is facing?
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