acg Posted August 7, 2022 Author Posted August 7, 2022 3 hours ago, davewantsmoore said: What do you mean by struggle..... non-flat frequency response... or something else? If it's the former, then "struggle" is kind of a misnomer.... as long as the response is corrected some other way. Why nitpick this?..... it's the way that general misunderstandings about the output Z and driver response get ingrained and passed on. Yes, very true, a lapse on my part, and you are correct. Hopefully the context offered in the post immediately above will show that for this specific application that a low output z amplifier is a good choice. And I also have to say that of the six channels in each DSET amplifier, only three have a low output impedance...horses for courses. 1
acg Posted August 11, 2022 Author Posted August 11, 2022 Midbass thoughts... Time to think about a midbass channel circa 40/50Hz to 100Hz/140Hz. The more I think about this the more I not only want it but the more it is likely required. I've got room mode problems at 40Hz, 51Hz, 55Hz, 117Hz and 139Hz. The higher two I should be able to allay with further room treatment but the lower few are more difficult and may not be able to be solved with bass traps. The best option I see is a midbass channel runing from the lower modes up to the lower knee of the upperbass horn which may or may not consequentially be tuned higher to suit. At hand I have three pair of Vitavox 15" alnico magnet, paper cone drivers that are either brand new or remagnetised/reconed: 2 new K15/40; two older K15/40; two older AK150. The AK150 are Fs = 35Hz and K15/40 are Fs= 45Hz. These are magnificent sounding drivers and have been used in everything from bass horns to sealed and vented speakers. One of my old pair were previously used for PA as guitar speakers. They aren't the best candidates for a sealed box but I do intend to try them that way myself. @davewantsmooreand I have been chatting/ranting privately about all kinds of things midbass and bass in general and one of the things that came up, not necessarily in regards to my playback, was open baffle midbass. I don't know too much about it to be honest having never been enamoured with any open baffle system I have heard and therefore never bothered to follow it up in any non-cursory way, but technically at least it may be a good fit here due to its directionality which may be very useful in terms of spraying less bass energy into places it does not need to be. I've got no clue if these Vitavox drivers are any sort of prospect for OB midbass, nor if OB Midbass could really be a useful solution for my playback, but I think it is worth investigating. Immediate intention, though, is to play with some sealed midbass and knock up some rough and ready mdf boxes and see what sort of in-room response I can get from the 15"ers. It could be a close-run thing as to whether I have enough volume from a single driver to match the Bass Cannons and Upperbass Horns, but I can easily throw up a second or third driver to accommodate. There are three potential locations for the midbass channel. First, the room as it is right now... Midbass Option #1...a single driver on top of the horn stack... Midbass option #2...a single or pair of drivers inside the stack at floor level... Midbass Option #3...a single or pair or trio of drivers hooked on the outside of the horn stack... I could even split a pair with each in any two of the three locations, which could be the best method to even out the room bass response. There is some flexibility there for midbass at different heights and in different parts of the room. For example, a trio could look like this... In terms of open baffle midbass, according to my cursory knowledge I think that Option #1 may be most suitable, but I don't know enough. I'll have to do some reading to figure some of this stuff out. The DSET amplifiers have a spare channel ready and waiting for midbass. 2
tripitaka Posted August 11, 2022 Posted August 11, 2022 16 minutes ago, acg said: Midbass thoughts... Time to think about a midbass channel circa 40/50Hz to 100Hz/140Hz. The more I think about this the more I not only want it but the more it is likely required. I've got room mode problems at 40Hz, 51Hz, 55Hz, 117Hz and 139Hz. The higher two I should be able to allay with further room treatment but the lower few are more difficult and may not be able to be solved with bass traps. The best option I see is a midbass channel runing from the lower modes up to the lower knee of the upperbass horn which may or may not consequentially be tuned higher to suit. At hand I have three pair of Vitavox 15" alnico magnet, paper cone drivers that are either brand new or remagnetised/reconed: 2 new K15/40; two older K15/40; two older AK150. The AK150 are Fs = 35Hz and K15/40 are Fs= 45Hz. These are magnificent sounding drivers and have been used in everything from bass horns to sealed and vented speakers. One of my old pair were previously used for PA as guitar speakers. They aren't the best candidates for a sealed box but I do intend to try them that way myself. @davewantsmooreand I have been chatting/ranting privately about all kinds of things midbass and bass in general and one of the things that came up, not necessarily in regards to my playback, was open baffle midbass. I don't know too much about it to be honest having never been enamoured with any open baffle system I have heard and therefore never bothered to follow it up in any non-cursory way, but technically at least it may be a good fit here due to its directionality which may be very useful in terms of spraying less bass energy into places it does not need to be. I've got no clue if these Vitavox drivers are any sort of prospect for OB midbass, nor if OB Midbass could really be a useful solution for my playback, but I think it is worth investigating. Immediate intention, though, is to play with some sealed midbass and knock up some rough and ready mdf boxes and see what sort of in-room response I can get from the 15"ers. It could be a close-run thing as to whether I have enough volume from a single driver to match the Bass Cannons and Upperbass Horns, but I can easily throw up a second or third driver to accommodate. There are three potential locations for the midbass channel. First, the room as it is right now... Midbass Option #1...a single driver on top of the horn stack... Midbass option #2...a single or pair of drivers inside the stack at floor level... Midbass Option #3...a single or pair or trio of drivers hooked on the outside of the horn stack... I could even split a pair with each in any two of the three locations, which could be the best method to even out the room bass response. There is some flexibility there for midbass at different heights and in different parts of the room. For example, a trio could look like this... In terms of open baffle midbass, according to my cursory knowledge I think that Option #1 may be most suitable, but I don't know enough. I'll have to do some reading to figure some of this stuff out. The DSET amplifiers have a spare channel ready and waiting for midbass. I always like to read your updates but my word this project has a tendency to keep expanding in scope/complexity!
Silent Screamer Posted August 11, 2022 Posted August 11, 2022 (edited) 8 minutes ago, tripitaka said: I always like to read your updates but my word this project has a tendency to keep expanding in scope/complexity! Feature creep is a real danger in the programming world. You can keep expanding on the project to the point it gets abandoned because it has deviated so far from the original brief that it is no longer viable. Could very well see that happening here if he isn't careful. I am very slowly learning in life... Just because you can, doesn't mean you should. (he says while currently writing a program and keeps adding new features). Edited August 11, 2022 by Silent Screamer
acg Posted August 11, 2022 Author Posted August 11, 2022 39 minutes ago, tripitaka said: I always like to read your updates but my word this project has a tendency to keep expanding in scope/complexity! Sort of. The midbass has always been planned as much as for a contingency as for an inevitability. The amp has been built and incorporated with the five other channels and I've been collecting the drivers for some time (they are rare). 36 minutes ago, Silent Screamer said: Feature creep is a real danger in the programming world. You can keep expanding on the project to the point it gets abandoned because it has deviated so far from the original brief that it is no longer viable. Could very well see that happening here if he isn't careful. Ha! It would take me longer to break down my system and get it out of the room than it would to just get in and build the midbass. Theoretically of course. Should only take a few hours to knock up some rough boxes for the first phase of testing. 1
tripitaka Posted August 11, 2022 Posted August 11, 2022 2 minutes ago, acg said: Sort of. The midbass has always been planned as much as for a contingency as for an inevitability. The amp has been built and incorporated with the five other channels and I've been collecting the drivers for some time (they are rare). Ha! It would take me longer to break down my system and get it out of the room than it would to just get in and build the midbass. Theoretically of course. Should only take a few hours to knock up some rough boxes for the first phase of testing. Yep love your 'can do!' attitude ... pleased though that I'm not paying for this build at an hourly rate 1 1
almikel Posted August 11, 2022 Posted August 11, 2022 3 hours ago, acg said: @davewantsmooreand I have been chatting/ranting privately about all kinds of things midbass and bass in general and one of the things that came up, not necessarily in regards to my playback, was open baffle midbass. I don't know too much about it to be honest having never been enamoured with any open baffle system I have heard and therefore never bothered to follow it up in any non-cursory way, but technically at least it may be a good fit here due to its directionality which may be very useful in terms of spraying less bass energy into places it does not need to be. I was always impressed with the directivity plots @gainphile achieved from his OB speakers. 1
Pops110 Posted August 11, 2022 Posted August 11, 2022 (edited) 6 hours ago, acg said: Midbass thoughts... Time to think about a midbass channel circa 40/50Hz to 100Hz/140Hz. The more I think about this the more I not only want it but the more it is likely required. I've got room mode problems at 40Hz, 51Hz, 55Hz, 117Hz and 139Hz. The higher two I should be able to allay with further room treatment but the lower few are more difficult and may not be able to be solved with bass traps. The best option I see is a midbass channel runing from the lower modes up to the lower knee of the upperbass horn which may or may not consequentially be tuned higher to suit. At hand I have three pair of Vitavox 15" alnico magnet, paper cone drivers that are either brand new or remagnetised/reconed: 2 new K15/40; two older K15/40; two older AK150. The AK150 are Fs = 35Hz and K15/40 are Fs= 45Hz. These are magnificent sounding drivers and have been used in everything from bass horns to sealed and vented speakers. One of my old pair were previously used for PA as guitar speakers. They aren't the best candidates for a sealed box but I do intend to try them that way myself. @davewantsmooreand I have been chatting/ranting privately about all kinds of things midbass and bass in general and one of the things that came up, not necessarily in regards to my playback, was open baffle midbass. I don't know too much about it to be honest having never been enamoured with any open baffle system I have heard and therefore never bothered to follow it up in any non-cursory way, but technically at least it may be a good fit here due to its directionality which may be very useful in terms of spraying less bass energy into places it does not need to be. I've got no clue if these Vitavox drivers are any sort of prospect for OB midbass, nor if OB Midbass could really be a useful solution for my playback, but I think it is worth investigating. Immediate intention, though, is to play with some sealed midbass and knock up some rough and ready mdf boxes and see what sort of in-room response I can get from the 15"ers. It could be a close-run thing as to whether I have enough volume from a single driver to match the Bass Cannons and Upperbass Horns, but I can easily throw up a second or third driver to accommodate. There are three potential locations for the midbass channel. First, the room as it is right now... Midbass Option #1...a single driver on top of the horn stack... Midbass option #2...a single or pair of drivers inside the stack at floor level... Midbass Option #3...a single or pair or trio of drivers hooked on the outside of the horn stack... I could even split a pair with each in any two of the three locations, which could be the best method to even out the room bass response. There is some flexibility there for midbass at different heights and in different parts of the room. For example, a trio could look like this... In terms of open baffle midbass, according to my cursory knowledge I think that Option #1 may be most suitable, but I don't know enough. I'll have to do some reading to figure some of this stuff out. The DSET amplifiers have a spare channel ready and waiting for midbass. Would it be possible to move the bass towers apart and have the mid bass on the inside of the bass towers? Just wondering if they would work better at ear heights and closer to the other speakers? Edited August 11, 2022 by Pops110
acg Posted August 11, 2022 Author Posted August 11, 2022 9 hours ago, Pops110 said: Would it be possible to move the bass towers apart and have the mid bass on the inside of the bass towers? Just wondering if they would work better at ear heights and closer to the other speakers? The bass towers cannot be moved further out unfortunately as I am limited by the trapdoor on the left side of the room in those images. Option #2 above has the midbass on the floor in between the speakers but this is my least favourite option. With any luck I will have enough volume for a single 15" per side and I can put it up on top of the horn stack, or maybe split a pair to make better use of the room and modes. Lots of experimenting ahead...
davewantsmoore Posted August 11, 2022 Posted August 11, 2022 (edited) 15 hours ago, acg said: They aren't the best candidates for a sealed box but I do intend to try them that way myself. Aside from the lack of excursion capability.... there is only one "problem" with these driveres in a sealed box. [It is v. similar the OB correction discussion we recently had in PM] Because the driver has a strong motor.... the rolloff will start quite high in frequency.... and so through the range you wish to use the driver it won't have a flat frequency response (it could be very not flat). ie. the bass will be missing. 15 hours ago, acg said: I don't know too much about it to be honest having never been enamoured with any open baffle system I have heard and therefore never bothered to follow it up in any non-cursory way, but technically at least it may be a good fit here due to its directionality which may be very useful in terms of spraying less bass energy Not bass energy (although this depends on what people consider "bass") ... as bass is omni directional. It is about the directivity in the >> 100Hz range.... eg. 200, 300, 400Hz. (-6dB point of XO in mine is a bit over 300Hz) Also the reasoning is to keep the Fs of the system low (alternatively, putting the driver in a sealed box is going to raise it's electro mechanical resonance into the range we want to use it.... where as putting it in an OB lower it (if anything) from the drivers (free air) Fs. 15 hours ago, acg said: I've got no clue if these Vitavox drivers are any sort of prospect for OB midbass Certain drivers being good or bad for OB is basically a myth. Yes - Certain driver Q (shape) in the SPL response, coupled with a baffle size.... can give you a flat frequency response ... but if you have other response shaping things (like filters), then using those is much! higher performance was to shape the response. The real important perameters for "good at OB" are (very simple....) enough excursion for the application (ie. distortion vs SPL is not too high) ..... low self noise (eg. "wind" noise from behind the cone through the basket, etc.) 15 hours ago, acg said: There are three potential locations for the midbass channel. Assuming you are running them down to 60Hz or so... then I think the excursion willl be too large for them to be hooked to the horn stack. Put them on the floor. Edited August 11, 2022 by davewantsmoore 1
davewantsmoore Posted August 11, 2022 Posted August 11, 2022 15 hours ago, tripitaka said: I always like to read your updates but my word this project has a tendency to keep expanding in scope/complexity! Was always on the cards. Subwoofers are designed so they can't reach up high enough (internal box resonance issues) ... and horn does not reach down low enough. I have resisted saying (as I think it is waaay beyond this being an option) .... but the drivers in the "bass cannons" would be perfect for 60 to 200 ..... put them in a box where they can do that (and ditch the steel "bass cannons") .... then then build real subwoofers (10 to 60) that can be placed "anywhere").
davewantsmoore Posted August 11, 2022 Posted August 11, 2022 (edited) 14 hours ago, almikel said: I was always impressed with the directivity plots @gainphile achieved from his OB speakers. The only way to build speakers which dont turn into a "hall of mirors" (due to huge frequency response distortion vs angle) ... is really a large horn, or a dipole ("open baffle") (and maybe a few other esoteric things). Paradoxically.... they are both normally done the most unsuitable way. For an OB, to maintain the directivity (using typical "cone shaped" drivers) .... the speaker needs to be multiway. Really 4-way..... but as we see, many open baffles are done as single driver (or single driver, plus bass woofer). Conversely for a horn.... a multiway appoach ends up with mismatched directivity due to the size and shape of the things.... so you really need a single horn. That being said.... 4-way open baffle.... or single fullrange horn .... are both relatively difficult to make. To be clear, this doesn't make (single) OB speakers, or (multi) horn speakers... "bad". It just means they have the same issue / juggling act, that other typical speaker have (your bogo standard, 2 or 3 way, 20 to 40cm wide box) Edited August 12, 2022 by davewantsmoore 2
Silent Screamer Posted August 12, 2022 Posted August 12, 2022 @acg did you take the back off the Lazy 9's?
acg Posted August 12, 2022 Author Posted August 12, 2022 Well, I've done some quick room mode/speaker position calcs and from what I can tell the most useful midbass position (in terms of mitigation of the effects of room modes) is on top of the horn stack where it has the potential to really help the 51Hz and 55Hz modes in particular. On the floor between the horns is also useful, particularly when paired with absorption on the side walls. These 51Hz/55Hz modes can be attenuated using only bass absorption on the side walls, but midbass channel position looks to be able to do a fair bit of the heavy lifting by itself. I also had a look at the big 40Hz mode and it may just be treatable with bass traps (VPR's) on the front wall in addition to the big soft and fluffy trap and windows already at the back of the room, so I am a little less worried about that one now, although I will have to build VPR's that work at 40Hz. Ceiling treatment looks like it will only be needed for above 120Hz or so which is doable. 14 minutes ago, Silent Screamer said: @acg did you take the back off the Lazy 9's? No. I run B+ from the amplifier right up to the ribbon tweeter so I have cnc'd a billet of aluminium to make a case for the Lazy Ribbon so I don't accidently grab 200VDC. Pretty sure you can't take the back off them anyway...that is only possible in some of the smaller RAAL ribbons...
Silent Screamer Posted August 12, 2022 Posted August 12, 2022 The proper 140-15 AM dipoles I am using in my OB setup have that unit mounted above the ribbon. The 140-15 AM and 70-10 AM monopoles I have just have a plain back which I think can be cut off to make a dipole.
Silent Screamer Posted August 12, 2022 Posted August 12, 2022 @acg I didn't realize the Lazy 9 was a 210-10, I thought it was 15 wide the same as the 140's. They have effectively the same cone area. I thought the Lazy 9 was much bigger.
acg Posted August 12, 2022 Author Posted August 12, 2022 2 hours ago, davewantsmoore said: Subwoofers are designed so they can't reach up high enough (internal box resonance issues) ... and horn does not reach down low enough. That longitudinal resonance of the empty cannon (about 85Hz from memory) was completely eliminated with internal stuffing of the individual cannons. Gone completely from the electrical impedance, gone from the measured SPL and gone during subjective listening. With some outside the box thinking (literally - those external rings that allow the stack to stand vertically apply tremendous pre-tensioning to the steel) the steel is highly damped and extremely inert, more inert than the highly inert cabinets of the renowned Lenehan ML1 standmounts let alone pretty much any subwoofer out there. You cannot induce any sort of ring even with your knuckles, although you will hurt your knuckles if you try hard enough, and they are 400kg each side and pneumatically isolated from the floor so as not to induce vibrations into the room. Plus they are flat to 18Hz in room and sound so soft and beautiful. From memory they had a good response past 500Hz and maybe to 1kHz, but they just don't sound great up there. Romy puts it down to the rubber surrounds on the drivers...I don't know. 2 hours ago, davewantsmoore said: I have resisted saying (as I think it is waaay beyond this being an option) .... but the drivers in the "bass cannons" would be perfect for 60 to 200 ..... put them in a box where they can do that (and ditch the steel "bass cannons") .... then then build real subwoofers (10 to 60) that can be placed "anywhere"). Those Scanspeak drivers are too low sensitivity and low excursion to be used sparingly in this system and I would still need to use most of them for midbass if I wanted to match the sensitivity of the horns above. Either way it is a lot of drivers whether midbass or sub-bass and really their best sound is where they are currently used. "Real subwoofers" as you call them Dave are of no use in this system. They necessitate the use of large excursion drivers, DSP and high power amplifiers none of which I shall entertain. That will sound stupid to some but it is what it is...unless I can run the sub to 110dB SPL at 18Hz with 9 watts of SET power it does not fit within the scope of this system. The Bass Cannons are a good solution within the (stupid analogue only) parameters of this build and they are already embedded within the room well enough that I think I can get a good flat in-room response with use of a midbass channel and the right room treatment. Fingers crossed. I really am building a dinosaur here: all analogue, massive in size and weight, based on some of our oldest audio technologies with mostly ancient drivers and vacuum tubes. Probably the most difficult way to skin the cat, but I'm loving it! 2
Silent Screamer Posted August 12, 2022 Posted August 12, 2022 I have to admit when you went down the path of the stacked cannons, I didn't think it was the most sensible way of doing things, it seemed over complicated and I questioned it would be effective. But there are many roads that lead to Rome. Can hardly get any more inefficient than I have with an 18" driver sitting in free air, but it does what I want, and at the end of the day it is our individual journey's. The more it went on, the more I started liking the idea. Stick with what you have if you can make it work.
acg Posted August 12, 2022 Author Posted August 12, 2022 3 hours ago, davewantsmoore said: Aside from the lack of excursion capability.... there is only one "problem" with these driveres in a sealed box. [It is v. similar the OB correction discussion we recently had in PM] Because the driver has a strong motor.... the rolloff will start quite high in frequency.... and so through the range you wish to use the driver it won't have a flat frequency response (it could be very not flat). ie. the bass will be missing. Yes, I am aware of the very not flat possibility. These Vitavox drivers will not have much excursion capability. 3 hours ago, davewantsmoore said: Also the reasoning is to keep the Fs of the system low (alternatively, putting the driver in a sealed box is going to raise it's electro mechanical resonance into the range we want to use it.... where as putting it in an OB lower it (if anything) from the drivers (free air) Fs. Yes, that is a good reason for OB. 3 hours ago, davewantsmoore said: Certain drivers being good or bad for OB is basically a myth. Yes - Certain driver Q (shape) in the SPL response, coupled with a baffle size.... can give you a flat frequency response ... but if you have other response shaping things (like filters), then using those is much! higher performance was to shape the response. The real important perameters for "good at OB" are (very simple....) enough excursion for the application (ie. distortion vs SPL is not too high) ..... low self noise (eg. "wind" noise from behind the cone through the basket, etc.) Compensation filters could be added at the input to the amplifier for this channel. Gotta love the idea of purposefully giving an amplifier a non-flat frequency response! No idea about wind noise from the back of the cone, but the basket looks reasonably open according to this drawing... ...and this photo... I assume that given the upper range of the midbass channel that the preferred physical format would be with the driver hanging in free-air ala Kyron... Those woofers ^^^^ look much more open basket
acg Posted August 12, 2022 Author Posted August 12, 2022 23 minutes ago, Silent Screamer said: Stick with what you have if you can make it work. I think what Dave is mostly concerned about is the lack of flexibility of positioning my subs within the room. They are huge. A multi-sub approach with strategic positioning is quite an efficient way to deal with room modes, or more importantly to get a flat frequency response for the bass. Some of my fundamental system decisions have negated this possibility for now, at least in their most effective format, but there is some leeway with the midbass channel doing at least part of what multiple subs would achieve...maybe.
Silent Screamer Posted August 12, 2022 Posted August 12, 2022 (edited) They look like the little brother of the Kyron I saw at the audio show. But from memory they had a decent Scanspeak tweeter, Scanspeak 12MU's and Acoustic Elegance OB woofers (higher Qts than the regular range of drivers). Was very impressed with the sound. I ranked them as number one OB system of the show. Edited August 12, 2022 by Silent Screamer
Silent Screamer Posted August 12, 2022 Posted August 12, 2022 3 minutes ago, acg said: I think what Dave is mostly concerned about is the lack of flexibility of positioning my subs within the room. They are huge. A multi-sub approach with strategic positioning is quite an efficient way to deal with room modes, or more importantly to get a flat frequency response for the bass. Some of my fundamental system decisions have negated this possibility for now, at least in their most effective format, but there is some leeway with the midbass channel doing at least part of what multiple subs would achieve...maybe. I remember seeing them in person, they are not the sort of thing you can move around the room by yourself (or probably several people). OK see what you are trying to do. Time for a new room then? lol
davewantsmoore Posted August 12, 2022 Posted August 12, 2022 3 hours ago, acg said: That longitudinal resonance of the empty cannon (about 85Hz from memory) was completely eliminated with internal stuffing Ah. So what made you say they "we only good to 100hz or so" then? 3 hours ago, acg said: Plus they are flat to 18Hz in room No doubt.... the only reason for "other subwoofers" was something which can be placed freely .... and because you probably don't want the excursion of the very very lowest frequencies intermingling with the octaves above. 3 hours ago, acg said: and sound so soft and beautiful All low distortion bass sounds like this 3 hours ago, acg said: Those Scanspeak drivers are too low sensitivity and low excursion to be used sparingly in this system and I would still need to use most of them for midbass if I wanted to match the sensitivity of the horns above. Yes... I was still thinking you would use them all.... in one box (per side). If there's no issue with using them from ~60 to ~150 .... then just do that (and build subwoofers). 3 hours ago, acg said: "Real subwoofers" as you call them Dave are of no use in this system. They necessitate the use of large excursion drivers, DSP and high power amplifiers none of which I shall entertain. No they don't. You just need large driver area... and they do not need DSP. You seem to be misunderstanding what I am suggesting. It is simply instead of making a new channel to cover 50 to 150 .... you could use your bass cannons (they would be perfect there). If they can go up to 150 ok (I thought there was a problem) .... then don't change them at all. Then build subwoofers. They can be placed literally anywhere (everywhere) .... which will smooth the modal response of the room. This will (potentially) solve your "placement conundrum" for the mid bass channel. The bass cannons stay right where they are and cover 50 to 200. 3 hours ago, acg said: That will sound stupid to some but it is what it is...unless I can run the sub to 110dB SPL at 18Hz with 9 watts of SET power it does not fit within the scope of this system. So the subs I am suggesting are going to be about as big (litres) as the bass cannons.... but the advantage is you can put that box(es) anywhere in the room. Anyways... might no work for you. 3 hours ago, acg said: I really am building a dinosaur here: all analogue, massive in size and weight, based on .... Yes, I not trying to suggest you do anything else. To recap: Don't tack a mis bass channel on to the side (or top) of the bass cannons ..... repurpose the bass cannons for 50 to 200... those drivers would be excellent there, and the "stack" is very well located. Then solve the 20 to 60 issue. You could even use horns! 1
acg Posted August 12, 2022 Author Posted August 12, 2022 2 hours ago, davewantsmoore said: Ah. So what made you say they "we only good to 100hz or so" then? This... 6 hours ago, acg said: From memory they had a good response past 500Hz and maybe to 1kHz, but they just don't sound great up there. Romy puts it down to the rubber surrounds on the drivers...I don't know. 2 hours ago, davewantsmoore said: It is simply instead of making a new channel to cover 50 to 150 .... you could use your bass cannons (they would be perfect there). If they can go up to 150 ok (I thought there was a problem) .... then don't change them at all. Then build subwoofers. They can be placed literally anywhere (everywhere) .... which will smooth the modal response of the room. I do understand this perspective but the lowest amplifier channel has been specialised for the 1 ohm load that the Bass Cannons present. It will still be great for midbass duties but then I doubt I would be able to find a sub speaker solution to suit the next amplifier channel which I can rewire for an 8 ohm or 16 ohm load but still only have 8 watts. Overall, it might be easier to investigate the midbass channel with the Vitavox woofers because they should have the frequency range necessary to also work with the problem room modes. It might be a dead end, but this was knocked up in a couple of hours after work this afternoon... It is as rough as guts but should be good for assessing the potential of a midbass channel. The second cabinet has been cut...I just need to glue it up in the morning. 2 hours ago, davewantsmoore said: Then solve the 20 to 60 issue. You could even use horns! Do you mean a tapped horn or two? They have been considered but I've no idea how to time align them in analogue. I definitely have options, whether I end up with the midbass channel or spread the Bass Cannons a bit wider or I repurpose the Cannons and build some subs to spread about the room. Time will tell.
davewantsmoore Posted August 13, 2022 Posted August 13, 2022 17 hours ago, acg said: I do understand this perspective but the lowest amplifier channel has been specialised for the 1 ohm load that the Bass Cannons present. It will still be great for midbass duties So it could drive the "bass cannons" from 50 to 150 (ish) ?! This would also be an improvement in another area (that I don't know if I mentioned) which is then the cannons would be operating above their electromechanical resonance area..... where as right now that resonance must be right in the middle of their passband somewhere. As mentioned... thas is (one of the) reasons for my OB. Move the resonance outside the passband. 17 hours ago, acg said: but then I doubt I would be able to find a sub speaker solution to suit the next amplifier channel which I can rewire for an 8 ohm or 16 ohm load but still only have 8 watts. At a real quick calc 4x 18" drivers that are 84dB/w @20Hz each ..... gets you to 105dB@20Hz with 8 watts .... before any "room gain". So, it's all within the realms of possbiility.... like the bass cannons, it's just a matter of having enough driver area and/or box size. A large driver (say a 15") in a corner loaded horn will do it too, if you're ready for like a 500L+ box... the pass band ripple from a "shortened" horn just won't be seen in practise when firing into a room (a tiny box wrt wavelength). 17 hours ago, acg said: It might be a dead end, but this was knocked up in a couple of hours after work this afternoon... This looks quite small. The small box, coupled with the strong motor is going to give you a very sloping response through your intended passband (ie. no bass) .... just something to be aware of if you're doing a listening test with no correction. 17 hours ago, acg said: Do you mean a tapped horn or two? They have been considered but I've no idea how to time align them in analogue. No... I don't really think of a "tapped horn" as a horn..... but you could. I was thinking of a normal (front loaded) horn with a corner loaded mouth.... it's a pretty big project though - both in difficulty and in litres (and a departure from your current plan) ... so more realistically I was really just thinking large sealed boxes, place in the corners, or out of the way 'somewhere'.
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