Red Accuton 17 cm driver @ 1 Watt, Black at x-max (20 Hz), Green Wavecor 10 inch PP @1 Watt, Blue Wavecor PP with Monacor plate amp @200 Watt.
Looks like more than enough headroom. How did you port the Accuton? I used a 6.8 cm diameter port in the graph. Are you going to close the port?
Then you clearly do not understand the design of the PR-Bandpass in which i speak. It is broad bandwidth from 22 to 65Hz anechoic with boost applied, and is in no way designed for output at the majority of one note like those old ported one size fits all car boxes of the '90s. This is different.
As a nod, Geddes used to sell a design just like this based on a PR that is NLA.
It is a sound design, and worth the cost.
Thanks for the great discussion. I'm learning a lot from this. Clearly, there are many possible paths and debating them is great for learning about them and eventually chosing one I can feel comfortable with...
Some thoughts re. the points you all raised:
I don't think I'm being overconvident. I'm trying to understand what the various approaches entail and pattern match that to my current skill/understanding and what a additional knowledge I can possibly pick up in the process. When I can come up with a plan for something, I can build it. I also need to be able to understand the theory behind it so I can fix and/or optimize it in practice.
re. DSP for bass-management. I am not totally against that route. I think with how I have things planned, it could come as a future increment. A decent plate-amp will have both Speaker-Level and Line-Level inputs. Starting with the speaker input tapped off of the main speaker connections of the power amp would be an easy starting point. The inputs have a high impedance (20k on the Sam-2) so those sitting parallel to the main speakers should not be noticeble from the perspective of the amp/main-speakers in any significant way.
I do realize that room-response (nodal frequencies) pose a problem. I have done some accoustic treatment of the room for the higher freqencies but nothing for the lows. There is a somewhat nasty standing wave at around 75 Hz here already. Experiemnting with a plate-resonator at some point is something on my project list. I don't think (please correct me if I'm wrong) a DSP will help with that. Boosting a frequency that yields a standing wave in the room will not change the physical properties of the room so the effect that there are positions where that frequency gets attenuated quite severly will continue. Still, I'm open to experimenting with a DSP in front of the power-amps input to manage what goes into the amp+mainspeakers vs. the subwoofer. That can just work as a drop-in upgrade at some point if need be.
The measured response (uncalibrated microphone, decent audio-interface and REW) shows that bass response drops off at around 40 Hz which is consistent with what simulation predicts with the driver, box and crossover parameters blogged in for the C-173-6-191 accuton drivers:
Box volume is about 18l, Port diameter 50mm, port length 150mm. Simulated response for the closed system in red.
The redcatt 10" drivers yield some pretty good curves when simulated with a 30-40l box and HPF (~1500-200 µF). They come in an aluminium cone version but that seems to be out of stock at this time. Maybe the standard version is enough. This is the blue response (without any LPF applied)
I've adjusted the input level for each curve so that they line up for comparison.
The wavecor reaches a bit lower still...
Cheers!
Some thoughts re. the points you all raised:
I don't think I'm being overconvident. I'm trying to understand what the various approaches entail and pattern match that to my current skill/understanding and what a additional knowledge I can possibly pick up in the process. When I can come up with a plan for something, I can build it. I also need to be able to understand the theory behind it so I can fix and/or optimize it in practice.
re. DSP for bass-management. I am not totally against that route. I think with how I have things planned, it could come as a future increment. A decent plate-amp will have both Speaker-Level and Line-Level inputs. Starting with the speaker input tapped off of the main speaker connections of the power amp would be an easy starting point. The inputs have a high impedance (20k on the Sam-2) so those sitting parallel to the main speakers should not be noticeble from the perspective of the amp/main-speakers in any significant way.
I do realize that room-response (nodal frequencies) pose a problem. I have done some accoustic treatment of the room for the higher freqencies but nothing for the lows. There is a somewhat nasty standing wave at around 75 Hz here already. Experiemnting with a plate-resonator at some point is something on my project list. I don't think (please correct me if I'm wrong) a DSP will help with that. Boosting a frequency that yields a standing wave in the room will not change the physical properties of the room so the effect that there are positions where that frequency gets attenuated quite severly will continue. Still, I'm open to experimenting with a DSP in front of the power-amps input to manage what goes into the amp+mainspeakers vs. the subwoofer. That can just work as a drop-in upgrade at some point if need be.
The measured response (uncalibrated microphone, decent audio-interface and REW) shows that bass response drops off at around 40 Hz which is consistent with what simulation predicts with the driver, box and crossover parameters blogged in for the C-173-6-191 accuton drivers:
Box volume is about 18l, Port diameter 50mm, port length 150mm. Simulated response for the closed system in red.
The redcatt 10" drivers yield some pretty good curves when simulated with a 30-40l box and HPF (~1500-200 µF). They come in an aluminium cone version but that seems to be out of stock at this time. Maybe the standard version is enough. This is the blue response (without any LPF applied)
I've adjusted the input level for each curve so that they line up for comparison.
The wavecor reaches a bit lower still...
Cheers!
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There's a lot of advice I don't understand here. The guy is using 35 watts to drive a pair of speakers with 7" drivers which are good down to 40Hz. After discussing power distribution across the audible frequency range I've no idea why you'd need 150 watts on sub-bass. Zackplonk has obviously spent a lot of money on 'quality'. The quality issue on sub-bass is open for debate. There is very little musical below 40Hz, and what's down there ain't pretty. If were Zackplonk I'd spent some time listening to a sub-40Hz sub on its own before making a decision.
I seriously doubt that DSP is going to work for a man with a system based on a 35 watt tube amp. DSP delay = 100% distortion.
Finally, bandpass is a complete joke. The concept is designed for car enthusiasts who don't need to pay for watts but are too cheap buy a crossover. In very basic terms: a sealed enclosure offers you full value as to what is coming out of the front of the speaker. A vented enclosure utilises the output from the rear of the driver to enhance the output of your chose frequency by 3dB. A bandpass enclosure suppresses the output from the front of the driver and focusses on frequency you want to enhance. Lay-man's terms: you are in the living room, sealing an hi-power driver in the bathroom, and opening the cat-flap.
I seriously doubt that DSP is going to work for a man with a system based on a 35 watt tube amp. DSP delay = 100% distortion.
Finally, bandpass is a complete joke. The concept is designed for car enthusiasts who don't need to pay for watts but are too cheap buy a crossover. In very basic terms: a sealed enclosure offers you full value as to what is coming out of the front of the speaker. A vented enclosure utilises the output from the rear of the driver to enhance the output of your chose frequency by 3dB. A bandpass enclosure suppresses the output from the front of the driver and focusses on frequency you want to enhance. Lay-man's terms: you are in the living room, sealing an hi-power driver in the bathroom, and opening the cat-flap.
I guess you don't have to believe me. It's a solid performer. Again, it's not a ported bandpass, and even Geddes used to sell a 15" inch design that was similar. Everyone that has heard it has liked it, and it does a lot very well.
I guess haters are just gonna hate. It is far from a joke, and is very clean and musical.
I guess haters are just gonna hate. It is far from a joke, and is very clean and musical.
I really appreciate you pointing me to your project, especially since proven projects were what I had specifically asked for.
I’m a bit convinced at this point, that a CB with HPF is something I want to try at this point as I can understand the theory behind that well and work from first principles.
Using PRs and such things are going to come in the future for sure.
You are welcome! It was at least proven, after 3 years of trying to get what I wanted from the onset.
I love you guys, with your book-learnin' stuff. Y'all tryin' to defeat science with your fancy spreadsheet equations. A sealed enclosure is what it is: you get what you pay for from the the front of the driver. A passive radiator is another spreadsheet wet-dream, Essentially, it's an unpowered driver but show me a design with a 10" driver and a passive radiator and I'll show a design with two ten inch drivers that will kick its ***. In the world of subwoofers, the roll-off argument is moot. Why would anybody be interested in the behaviour of frequencies they cannot hear? The logic behind ported enclosures is fairly simple: a 'free' 3dB increase at the frequency of your choosing,
In the words of Wesley Snipes, "listen to the woman". Zackplonk has a 35 watt tube amp and $500 worth of 7" bass drivers, a ten-inch ported sub will probably seem him right. Stop trying to sell him your wet dreams.
In the words of Wesley Snipes, "listen to the woman". Zackplonk has a 35 watt tube amp and $500 worth of 7" bass drivers, a ten-inch ported sub will probably seem him right. Stop trying to sell him your wet dreams.
I love all the assuptions, worked with drivers from: Wavecor, Monacor, Visaton, Dayton, etc in 6, 8, 10, 12 and 15 inch. In push-push, closed, closed with highpass, vented, bandpass, ripole and dipole. Just trying to help someone out, not selling anything.
Under the laws of physics, small and high quality are mutually exclusive. No amount of advertising can correct that, though servo can to some extent if it is ever done well enough. ( not yet in my experience)
My "music" subs are old Peerless 12" XLXX paper-carbon "critically damped" so about two cubic feet each to get my solid 30 Hz notes that sound natural. I am rather picky about distortion, so active crossover HP and LP for the sub, HP to the mains. I believe ALL speakers should have a HP filter to control excursion below Fs. Yea, more phase and group delay, but a valid tradeoff IMHO.
One can force a smaller sub lower with a Linkwitz Transform, but not to my likening. Some drivers can be used in smaller boxes with a PR as otherwise ports get unreasonable. You can get the box smaller with isobaric, but I have never been happy with the distortion. I prefer to use the two drivers direct. Hint: Distortion skyrockets at about 1/2 X-Max. Even for a sub, I like to stay below 2% or so. Others are happy with 10 or more. We are far less sensitive to LF distortion than up in the midrange fortunately.
I agree, DSP is the easiest way to integrate a sub, though one should not ignore the room. One reason I prefer sealed subs is it is easier to use their rolloff and room gain to complement. I ran two subs with no eq for years and they were very good. Fix what you can, then eq the last bit. The distortion added by the DSP is not as significant as it is at higher frequencies. I am actually looking at a MUTO M4 DAC so I can do the filtering and eq all with Equalizer APO (freeware) for my music system. The M4 DAC is actually better than a lot of them for 10 times the price! A lot of folks go MiniDsp rather than a Windows desktop. BUT, resist the temptation for boost! Do your models for excursion. So often I see horrendous distortion because someone was trying to boost out of a null. And even more, I see people trying to get a flat sub response in a model to 20 or so Hz, ignoring room gain. BOOM BOOM BOOM. Again, advantage to sealed alignments. They can also use lower frequency HP filters to keep the cone firmly attached to the suspension than ported.
With regards to band pass alignments, It is very hard to get a wide bandwidth but possible. As mentioned, most are one note wonders because they are incorrectly designed. A tendency, not necessary if you know what you are doing. Driver selection is very difficult. I still think they have some huge advantages as far as lower distortion, but very hard to do. I found just using more drivers with lower excursion to work better so instead of filtering the harmonics, don't produce them. I was getting there but requirements for things like 34 foot ports sent me back to traditional low Q, 2 drivers in push-pull.
PS: 35W. I envy. My biggest tube was 12W. ( Old HK Citation, POOGE'ed) More than enough for my office but would not have quite cut it in my living room. I find about 60W to be about right.
My "music" subs are old Peerless 12" XLXX paper-carbon "critically damped" so about two cubic feet each to get my solid 30 Hz notes that sound natural. I am rather picky about distortion, so active crossover HP and LP for the sub, HP to the mains. I believe ALL speakers should have a HP filter to control excursion below Fs. Yea, more phase and group delay, but a valid tradeoff IMHO.
One can force a smaller sub lower with a Linkwitz Transform, but not to my likening. Some drivers can be used in smaller boxes with a PR as otherwise ports get unreasonable. You can get the box smaller with isobaric, but I have never been happy with the distortion. I prefer to use the two drivers direct. Hint: Distortion skyrockets at about 1/2 X-Max. Even for a sub, I like to stay below 2% or so. Others are happy with 10 or more. We are far less sensitive to LF distortion than up in the midrange fortunately.
I agree, DSP is the easiest way to integrate a sub, though one should not ignore the room. One reason I prefer sealed subs is it is easier to use their rolloff and room gain to complement. I ran two subs with no eq for years and they were very good. Fix what you can, then eq the last bit. The distortion added by the DSP is not as significant as it is at higher frequencies. I am actually looking at a MUTO M4 DAC so I can do the filtering and eq all with Equalizer APO (freeware) for my music system. The M4 DAC is actually better than a lot of them for 10 times the price! A lot of folks go MiniDsp rather than a Windows desktop. BUT, resist the temptation for boost! Do your models for excursion. So often I see horrendous distortion because someone was trying to boost out of a null. And even more, I see people trying to get a flat sub response in a model to 20 or so Hz, ignoring room gain. BOOM BOOM BOOM. Again, advantage to sealed alignments. They can also use lower frequency HP filters to keep the cone firmly attached to the suspension than ported.
With regards to band pass alignments, It is very hard to get a wide bandwidth but possible. As mentioned, most are one note wonders because they are incorrectly designed. A tendency, not necessary if you know what you are doing. Driver selection is very difficult. I still think they have some huge advantages as far as lower distortion, but very hard to do. I found just using more drivers with lower excursion to work better so instead of filtering the harmonics, don't produce them. I was getting there but requirements for things like 34 foot ports sent me back to traditional low Q, 2 drivers in push-pull.
PS: 35W. I envy. My biggest tube was 12W. ( Old HK Citation, POOGE'ed) More than enough for my office but would not have quite cut it in my living room. I find about 60W to be about right.
Miller and Kreisel push pull is probably the best example I can use to add to this discussion. Kreisel designed subs that have won many awards. Sealed plus an understanding of physical limitations tied to thiel small parameters goes a long way. Throw in driver design and it's easy to understand how confusing bass can be. Sealed is an easy/dependable diy alignment vs everything else. Extension and spl for your buck are not as big in sealed...period. I still wouldn't have anything other than sealed for the low end and plug the ports on speakers for duty above that.
Thanks for that…
I‘m still struggling a bit on terminology. Is push-pull here referring to the same thing as push-push, where two drivers are working in phase but opposite to each other (so both pushing out at the same time) or is this something else? (Like in an PP-amp where each would take on one half of the wave)
Yep. That's what I asumme as well for push-push
Reading up a bit on push-pull, this seems to refer to a setup where 2 drivers are connected out of phase but one is mounted "inside out" and that is supposed to cancel out non-linearities/distortions.