I like your strategy.
I have used the same driver and also used off-axis listening and asymmetrical baffle-placement. I also used the baffle size to set the baffle step to the natural roll-off of the closed box enclosure, which together made up my all-acoustic high pass filter. It mated well to a (electrically filtered) woofersection, it was a FAST system. Never got a rulerflat measurement, but it sounded very good. In all honesty, it would probably have sounded better if I had made it fullrange with just the Monacor in a ported box. Instead, I chose bass extension.
I will be very curious to read how it works out for you.
I have used the same driver and also used off-axis listening and asymmetrical baffle-placement. I also used the baffle size to set the baffle step to the natural roll-off of the closed box enclosure, which together made up my all-acoustic high pass filter. It mated well to a (electrically filtered) woofersection, it was a FAST system. Never got a rulerflat measurement, but it sounded very good. In all honesty, it would probably have sounded better if I had made it fullrange with just the Monacor in a ported box. Instead, I chose bass extension.
I will be very curious to read how it works out for you.
Sorry for picture-less update! First braces are going in now but there isn't much to show yet. The edge sections might be tricky to cut as they need a slight angle. I'll try to figure out a jig for this.
Ivo, that sounds an interesting project. With a large baffle and one of these in a sealed box I suppose you'd arrive at a ~18dB roll-off slope. I imagine it performed quite well?
With my arrangement I plan to keep it as just the 2 speakers, though bass extension even in the ported design will be limited. I could add in a subwoofer with a 36dB electrical filter, which is about the roll-off rate of this driver in a ported box, the baffle reinforcement is assumed to be down to very low frequencies by utilising the rear wall. However, unlike your design, I will be risking excess excursion of the drivers by not using an electrical filter and without the protection offered by a sealed enclosure.
Ivo, that sounds an interesting project. With a large baffle and one of these in a sealed box I suppose you'd arrive at a ~18dB roll-off slope. I imagine it performed quite well?
With my arrangement I plan to keep it as just the 2 speakers, though bass extension even in the ported design will be limited. I could add in a subwoofer with a 36dB electrical filter, which is about the roll-off rate of this driver in a ported box, the baffle reinforcement is assumed to be down to very low frequencies by utilising the rear wall. However, unlike your design, I will be risking excess excursion of the drivers by not using an electrical filter and without the protection offered by a sealed enclosure.
I wouldn't have the space to accomodate any useful horn design. This is only 1.9L and it's at the limit of desk space I can allow (24x28cm). Wall mounting of the speakers wouldn't be possible as it's rented accomodation so no tacks in the wall!
Here's where I'm at. Both have the first brace in. One has the slim end panel affixed:
I couldn't cut that end panel section with its angle using my router, so I had to adjust the angle of my jigsaw base and cut the straightest line I could! It's not perfect, in fact, none of it is! I am loosing some confidence in this project, I think that if I can actually get it constructed to a functional level at least, that it'll then need a lot of filler and sanding to get it looking respectable. We will see I guess
Here's where I'm at. Both have the first brace in. One has the slim end panel affixed:
An externally hosted image should be here but it was not working when we last tested it.
I couldn't cut that end panel section with its angle using my router, so I had to adjust the angle of my jigsaw base and cut the straightest line I could! It's not perfect, in fact, none of it is! I am loosing some confidence in this project, I think that if I can actually get it constructed to a functional level at least, that it'll then need a lot of filler and sanding to get it looking respectable. We will see I guess
One problem you may run into with a design this slim is that the internal reflection from the back of the cabinet will interact with the drivers rear surface. This may be reduced by the angle of the cabinet but I would consider some kind of absorbtion directly behind the driver. Once it is built if you can do an impedance plot you should see a disturbance in the plot at the frequency or frequencies that it is ineracting at.
Regards,
Andrew
Regards,
Andrew
Hi,
Yes, this was a concern I had too. I fully intend to add a studio foam block behind the driver to help with this. Most the inside will be lined with felt also and the slim end will be stuffed with lambswool. I guess I might add some foam/wool on the top to attenuate top to bottom reflections too
Internal volume on these is being eaten up pretty fast. The inductors for the notch are quite hefty
Yes, this was a concern I had too. I fully intend to add a studio foam block behind the driver to help with this. Most the inside will be lined with felt also and the slim end will be stuffed with lambswool. I guess I might add some foam/wool on the top to attenuate top to bottom reflections too
Internal volume on these is being eaten up pretty fast. The inductors for the notch are quite hefty
internal & external (radial to the speaker ).
Here's where I'm up to:
I need to sand some of this down so the baffle will sit flush onto it, it's not all that accurately made despite my best efforts with a jigsaw and router
Then, I will install absorbent materials and the notch filter before mounting the baffle. I am intrigued by the cardboard idea, what type of card should be used? I have felt, lambswool and foam which I am planning to use so far, but I have very limited internal volume to spare.
Feeling a lot more solid, though still very light! I think I need additional bracing of that upper rear panel and it will be wise to somehow join the baffle to the end of the porting arrangement, otherwise that will have a large unsupported area on it.
An externally hosted image should be here but it was not working when we last tested it.
I need to sand some of this down so the baffle will sit flush onto it, it's not all that accurately made despite my best efforts with a jigsaw and router
Then, I will install absorbent materials and the notch filter before mounting the baffle. I am intrigued by the cardboard idea, what type of card should be used? I have felt, lambswool and foam which I am planning to use so far, but I have very limited internal volume to spare.
Feeling a lot more solid, though still very light! I think I need additional bracing of that upper rear panel and it will be wise to somehow join the baffle to the end of the porting arrangement, otherwise that will have a large unsupported area on it.
It did. It eventually evolved into a cork chamber containing the speaker, glued to a thin plywood baffle/outer box, which was filled with sand. It had a very tight, punchy sound, very dynamic and clear. There was still some sharpness in the treble peak. I could have played more with damping (inside and on the baffle), but I tired of the driver and the project. I moved to an open baffle with Omnes L8 (impressive), but haven't gotten very far yet with that project.
I am working on surround speakers with the miniature Visaton FRS 5 X now, which is in virtual stages. I have been testing them in the same enclosure and setting I described above for the Monacors and the result is mixed. Frequency range is better, overall tone and imaging is better, but dynamics and punch are less. It is, after all, little more than a tweeter with a bigger Xmax. You can't have your cake and eat it, too. Sigh.
Sounds like a very well damped enclosure! Should be almost completely inert with a small driver like that, though reflections are still a potential issue.
Just sanding some of the edges before I mount the baffle etc. I've been placing stuffing/absorbent materials today and installed the electrical notch a few days ago:
High density studio foam (leftover from my large speaker build)
sits behind the driver and on the bottom, to attenuate early reflections and top to bottom resonances respectively. Other surfaces near the driver rear have felt applied (30% wool) to hopefully reduce high frequency smearing. The rest is a fill of lambswool.
I will need to fit the binding posts before I mount the baffle, they won't be accessible afterwards. I cut the holes for them in the vinyl covering already, though it's quite a mess . Once they're in I can fit the baffle (once I've made it!)
These drivers don't have sealing gaskets, any simple (and discrete) reccomendations to create a seal? I remember trying to superglue an elastic band around the hole in the test cabinet, it did help but was messy and deteriorated. I suspect this driver is really designed for rear mounting, whereby the glued edge of the rubber surround will also act as a seal.
Just sanding some of the edges before I mount the baffle etc. I've been placing stuffing/absorbent materials today and installed the electrical notch a few days ago:
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
High density studio foam (leftover from my large speaker build)
sits behind the driver and on the bottom, to attenuate early reflections and top to bottom resonances respectively. Other surfaces near the driver rear have felt applied (30% wool) to hopefully reduce high frequency smearing. The rest is a fill of lambswool.
I will need to fit the binding posts before I mount the baffle, they won't be accessible afterwards. I cut the holes for them in the vinyl covering already, though it's quite a mess
. Once they're in I can fit the baffle (once I've made it!) These drivers don't have sealing gaskets, any simple (and discrete) reccomendations to create a seal? I remember trying to superglue an elastic band around the hole in the test cabinet, it did help but was messy and deteriorated. I suspect this driver is really designed for rear mounting, whereby the glued edge of the rubber surround will also act as a seal.
That's the stuff yeah, I haven't found any in small quantities yet though. I might have some around that I peeled off of something else. Alteranatively, I may be able to make one from a redundant mousepad!
These are looking nearly done, which is quite deceptive:
A lot of sanding, filling and sealer is needed before the vinyl covering can be applied. I don't think you could use a worse material than this plywood, really rough stuff. Both baffles are the same material, only one is the other way up, trying to choose the least rough side to go externally.
It's quite solid, though both exhibit one quite strong resonance when knocked in the small gap between the twin braces, which is surprising. It's high though so may not be too big an issue.
Will keep you updated
These are looking nearly done, which is quite deceptive:
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
A lot of sanding, filling and sealer is needed before the vinyl covering can be applied. I don't think you could use a worse material than this plywood, really rough stuff
. Both baffles are the same material, only one is the other way up, trying to choose the least rough side to go externally. It's quite solid, though both exhibit one quite strong resonance when knocked in the small gap between the twin braces, which is surprising. It's high though so may not be too big an issue.
Will keep you updated
Yes, an old mousepad made an ideal sealing gasket, not adhesive but otherwise ideal and seems to improve the tuning of the cabinet.
I've been testing out one cab with the driver installed. I have it up against the wall as it's designed to be used. I had intended to use bass boost on these but it turns out that's completely unnecessary!
That said, I get an excess of lower mid region, or so it seems. I'm guessing in reality that because they don't extend that deep it gives this impression. Using the Foobar EQ I can get it sounding fine by dropping the 150-300Hz region by a few dB. With this in effect they (currently 'it') does sound very respectable. Unfortunately this won't apply on Youtube videos or anything else, but this isn't really an issue. It's also possible that by moving the speakers slightly away from the wall I'll get less gain of this region whilst keeping the gain of the bass end but that cause cause other frequency anomalies.
Cabinet reflex tuning seems solid and also lower than my test cabinet so in practise internal volume has remained sufficient. I've not noticed any port noise but haven't tested this specifically, the test cabinet made noise at even moderate levels. Doesn't seem to be any cabinet resonances in practise, with the driver installed the cabinet doesn't exhibit much resonance under a knock test. It possibly doesn't sound as intimate/close as the test box which may be due to internal reflections, I may experiment with extra stuffing. It is more likely this is caused by a change in frequency response placing less emphasis on the vocal region though.
I've been testing out one cab with the driver installed. I have it up against the wall as it's designed to be used. I had intended to use bass boost on these but it turns out that's completely unnecessary!
That said, I get an excess of lower mid region, or so it seems. I'm guessing in reality that because they don't extend that deep it gives this impression. Using the Foobar EQ I can get it sounding fine by dropping the 150-300Hz region by a few dB. With this in effect they (currently 'it') does sound very respectable. Unfortunately this won't apply on Youtube videos or anything else, but this isn't really an issue. It's also possible that by moving the speakers slightly away from the wall I'll get less gain of this region whilst keeping the gain of the bass end but that cause cause other frequency anomalies.
Cabinet reflex tuning seems solid and also lower than my test cabinet so in practise internal volume has remained sufficient. I've not noticed any port noise but haven't tested this specifically, the test cabinet made noise at even moderate levels. Doesn't seem to be any cabinet resonances in practise, with the driver installed the cabinet doesn't exhibit much resonance under a knock test. It possibly doesn't sound as intimate/close as the test box which may be due to internal reflections, I may experiment with extra stuffing. It is more likely this is caused by a change in frequency response placing less emphasis on the vocal region though.
Ok, I've not had much luck with measuring in the past but I think this gives a fairly accurate representation:
This is a measurement taken with HOLMImpulse software with a WM-61A measurement mic I built (using generic calibration file) from about 40CM. Speaker located next to wall on bed, so one absorbent surface near it (which in reality will be a reflective desk). Graph is raw measurement (gated measurement gives nonsense result below gating frequency, always seems to for me, of course there's a reason but I don't understand it!) smoothed to 6th octave.
What I get from this is that the 10kHz driver peak is quite well controlled by the passive notch (measurement is on-axis). The excess energy around 120-300Hz is what I was hearing and had used EQ to lower, why this is here I'm not entirely sure? Definately to do with the near wall placement, but it should surely be equal to the top end, not overpowering. There also seems to be a broad peak between 1-2kHz*, I'm unsure why, however this is surprisingly inaudible/non-offensive; a possible cabinet resonance.
Can anyone shed any light on the excess 120-300Hz energy? If I can identify the cause I may be able to find an elegant solution. At the moment it's looking like using PC based DSP EQ or trying to squeeze an active notch filter into my compact amplifier.
For interest, I attach the EQ settings I came up with for Foobar, before taking the measurement. With this on it sounds rather good but this doesn't apply to DVDs etc.
EDIT *this actually shows on the driver response curve, I hadn't realised how significant it was.
An externally hosted image should be here but it was not working when we last tested it.
This is a measurement taken with HOLMImpulse software with a WM-61A measurement mic I built (using generic calibration file) from about 40CM. Speaker located next to wall on bed, so one absorbent surface near it (which in reality will be a reflective desk). Graph is raw measurement (gated measurement gives nonsense result below gating frequency, always seems to for me, of course there's a reason but I don't understand it!) smoothed to 6th octave.
What I get from this is that the 10kHz driver peak is quite well controlled by the passive notch (measurement is on-axis). The excess energy around 120-300Hz is what I was hearing and had used EQ to lower, why this is here I'm not entirely sure? Definately to do with the near wall placement, but it should surely be equal to the top end, not overpowering. There also seems to be a broad peak between 1-2kHz*, I'm unsure why, however this is surprisingly inaudible/non-offensive; a possible cabinet resonance.
Can anyone shed any light on the excess 120-300Hz energy? If I can identify the cause I may be able to find an elegant solution. At the moment it's looking like using PC based DSP EQ or trying to squeeze an active notch filter into my compact amplifier.
For interest, I attach the EQ settings I came up with for Foobar, before taking the measurement. With this on it sounds rather good but this doesn't apply to DVDs etc.
EDIT *this actually shows on the driver response curve, I hadn't realised how significant it was.
Attachments
Last edited:
I have finished the left one. Wasn't too difficult really with the oribital sander doing most the smoothing out. Two coats of sealer was plenty to make the wood smooth enough to take the vinyl well. I tried to keep the 'grain' on the top consistent with that on the wrap around for the best visual effect, it is Maple effect:
Not great photos, the light is fading. I'll do some better ones of the pair when the other is ready. You can see some of the mousepad sealing gasket spilling out, it's awkward because it isn't adhisive, effective though. Watch this space for completion of the second one
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Not great photos, the light is fading. I'll do some better ones of the pair when the other is ready. You can see some of the mousepad sealing gasket spilling out, it's awkward because it isn't adhisive, effective though. Watch this space for completion of the second one
Thanks!
Pleased to announce the pair are completed! Photos, with the little amp which powers them:
Most surprising feature of these is low level detail, seem to pick out everything. I guess lack of room reflections due to the close proximity is partly responsible, alongside the lightweight cone coupled to strong motor. It does also indicate to me that internal reflections from the rear wall are suitably attenuated.
Bass performance isn't bad at all really, quite useable without a subwoofer and without the hassles that brings (in my old uni room I got bass everywhere except at the desk, no matter where the sub was situated!). Stereo effect is naturally strong at this close range, perhaps not much imaging to speak of but I haven't really put them to much of a test yet.
I may try to get a little video of them playing, though it'd only give you a very rough idea of bass performance and general balance
Pleased to announce the pair are completed! Photos, with the little amp which powers them:
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Most surprising feature of these is low level detail, seem to pick out everything. I guess lack of room reflections due to the close proximity is partly responsible, alongside the lightweight cone coupled to strong motor. It does also indicate to me that internal reflections from the rear wall are suitably attenuated.
Bass performance isn't bad at all really, quite useable without a subwoofer and without the hassles that brings (in my old uni room I got bass everywhere except at the desk, no matter where the sub was situated!). Stereo effect is naturally strong at this close range, perhaps not much imaging to speak of but I haven't really put them to much of a test yet.
I may try to get a little video of them playing, though it'd only give you a very rough idea of bass performance and general balance
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