Good, the notes I am referring to is not in the 20ies but quite low by normal music standards. Like the Manger test-record: it is filled by good recordings and the bass-drum effect is at its best in this percussion group. Also I have the feeling that when we are really discussing bass we are very sure of our arguments. I tested the tracks of The Boys of Alabama's ATOM BOMB with a single B200 in OB 1 m x .75 m (about 3.5 mm linear X-max). It reached 85 dB exactly before it distorted although it had the bass capacity to go this low. My 'Volks-OB' bass units are nowhere near beeing bottomed by these tracks and normal SPLs !
/Erling
/Erling
skorpion said:
Right, but my motivation is not lowest organ pipe, lowest key on piano or lowest organ pipe ... I have not yet seen or heard a piano player using the lowest key and so forth ... so in that sense you are absolutely right that such things has noting to do with the music as such
BUT it seems that there is a lot of "room information" hidden in the lowest octaves ... or is that just "audiophile" talk
I suppose my goal with a 4way dipole with ribbon tweeter and ribbon supertweeter and a 6" lower mid/midbass would be sensitivity around 90db
someone has mentioned that 90db is pretty loud or at least a good deal more than normal listening level
I dont suppose that a 90db speaker will deliver a sound pressure of 90db with as little as 1watt
In the beginning it was mentioned that the AE IB15 will need LOTs of watts to play ... I dont suppose that is the case with the AE "DI 15" ... if there is such a thing
It should be clear by now that I know very little about decibel/SPL
As fore the fullrange-guys
Sure I understand what you are saying
High Qts woofers and a fullrange in a 2way
No doubt that the DIPOLE principle makes up fore the high Qts
What I dont fully understand is the use of fullrange drivers in dipoles, as far as I know fullrange drivers have VERY hard suspencion and would work more like midrange drivers
But I suppose one has to try it to understand
Another point would be that only few of us are able to build a multiway system, and should stick to what is pre-designed and ready to go
AND lets be honest that those are built and designed by our beloved fullrange-guys
So far I only know of MJKs design and now the Volks-OB(no Xover)
Another one that have had me puzzled is the use of very high sensitive fullrange combined with a low gain amp and a normal 90db woofer with a higher gain amp
Sure I understand what you are saying
High Qts woofers and a fullrange in a 2way
No doubt that the DIPOLE principle makes up fore the high Qts
What I dont fully understand is the use of fullrange drivers in dipoles, as far as I know fullrange drivers have VERY hard suspencion and would work more like midrange drivers
But I suppose one has to try it to understand
Another point would be that only few of us are able to build a multiway system, and should stick to what is pre-designed and ready to go
AND lets be honest that those are built and designed by our beloved fullrange-guys
So far I only know of MJKs design and now the Volks-OB(no Xover)
Another one that have had me puzzled is the use of very high sensitive fullrange combined with a low gain amp and a normal 90db woofer with a higher gain amp
Hi Ion,
This is the link I was thinking of;-
http://linkwitzlab.com/filters.htm
Roll down to section 9.
A mounted driver (whether enclosed or not) stores energy and has Q. Where the resultant Q is higher then EQ can compensate for the steady sine response, but not for the first cycle dynamic response because the initial energy lost to start the cone mass moving within its suspension spring still arises.
A lower Q driver has fast attack and good LF control/definition.
A higher Q driver (often low force factor) has slower attack and poorer LF definition.
A higher Q driver with EQ sounds strange due to the resultant delay of the compensation arising during the first cycle of say a drum kick or bass string pluck. The leading edge is not boosted (because the driver can still not respond fast enough) but the second half cycle onwards has increased amplitude.
This really does sound most unrealistic !
Yet the audible effect of EQ plus a higher Qes driver is not intuitively recognisable due to the amplitude envelope after the first cycle, and the typical decay of instrument notes being reproduced more correctly.
To me the sound is literally like 'Pumping Bass', as with many car systems, because the boost builds up during the first cycle, there being an additional LF component relating to the new LF turnover of the EQ itself.
The new LF component becomes superimposed upon all leading edges. It can be seen on the cone excursion and heard as a modulation of the entire LF output.
When this form of EQ is applied to a driver within an enclosure, which provides an increasingly resistive load to cone motion with falling frequency below Fs, then the EQ component is less likely to cause a driver cone to over excurse.
However, on an OB the increasing amplitude EQ drive with falling frequency is going to quickly run a driver into X.max limiting before a 'flat to 20Hz' in room response can be acheived, and that new LF turnover is going to have the cone spluttering non-linearly.
Tinitus above, rightly raises concerns here, for the alternative to listening at lower levels via an EQed dipole is to increase the driven cone area and/or X.lim to achieve genuine low frequency reproduction, or, to make the LF driver radiate more efficiently into the room, as with some frame or enclosure.
On the other hand, a dipole LS which rolls off naturally at the low end can be much more pleasant to listen to, especially when a lighter coned larger driver (less transduced energy lost to first cycle LF impulse cone motion) augments a widerange driver and the crossover circuits are minimal.
Cheers ........ Graham.
This is the link I was thinking of;-
http://linkwitzlab.com/filters.htm
Roll down to section 9.
A mounted driver (whether enclosed or not) stores energy and has Q. Where the resultant Q is higher then EQ can compensate for the steady sine response, but not for the first cycle dynamic response because the initial energy lost to start the cone mass moving within its suspension spring still arises.
A lower Q driver has fast attack and good LF control/definition.
A higher Q driver (often low force factor) has slower attack and poorer LF definition.
A higher Q driver with EQ sounds strange due to the resultant delay of the compensation arising during the first cycle of say a drum kick or bass string pluck. The leading edge is not boosted (because the driver can still not respond fast enough) but the second half cycle onwards has increased amplitude.
This really does sound most unrealistic !
Yet the audible effect of EQ plus a higher Qes driver is not intuitively recognisable due to the amplitude envelope after the first cycle, and the typical decay of instrument notes being reproduced more correctly.
To me the sound is literally like 'Pumping Bass', as with many car systems, because the boost builds up during the first cycle, there being an additional LF component relating to the new LF turnover of the EQ itself.
The new LF component becomes superimposed upon all leading edges. It can be seen on the cone excursion and heard as a modulation of the entire LF output.
When this form of EQ is applied to a driver within an enclosure, which provides an increasingly resistive load to cone motion with falling frequency below Fs, then the EQ component is less likely to cause a driver cone to over excurse.
However, on an OB the increasing amplitude EQ drive with falling frequency is going to quickly run a driver into X.max limiting before a 'flat to 20Hz' in room response can be acheived, and that new LF turnover is going to have the cone spluttering non-linearly.
Tinitus above, rightly raises concerns here, for the alternative to listening at lower levels via an EQed dipole is to increase the driven cone area and/or X.lim to achieve genuine low frequency reproduction, or, to make the LF driver radiate more efficiently into the room, as with some frame or enclosure.
On the other hand, a dipole LS which rolls off naturally at the low end can be much more pleasant to listen to, especially when a lighter coned larger driver (less transduced energy lost to first cycle LF impulse cone motion) augments a widerange driver and the crossover circuits are minimal.
Cheers ........ Graham.
Pano OB
Hello Panomaniac,
My OB setup is quite similar to yours, except I use a Hemp Acoustics FR6.5. The 15" woofer is an ATC and the cross over point is slightly lower - 2. order woofer & 1. order wideranger.
I have lived with this setup for 6 months and while it is quite good sounding, the wide range driver really does show some limitations in the upper midrange. Last I measured the Hemp it displayed a significant peak/dip in the 2.5 kHz region and another one in the 4-5 kHz area.
Personally, I am going to cross the Hemp to a cone tweeter in the near future. I guess I'll cross at 3 kHz and the reason for this is that while the breakup (I guess it's breakup) at 2.5 kHz is audible, the mess appearing at 4-5 kHz sounds the nastiest.
I think you would be well served with a tweeter handling the upper frequencies; one that does not have too wide a dispersion.
Best
Kris
Hello Panomaniac,
My OB setup is quite similar to yours, except I use a Hemp Acoustics FR6.5. The 15" woofer is an ATC and the cross over point is slightly lower - 2. order woofer & 1. order wideranger.
I have lived with this setup for 6 months and while it is quite good sounding, the wide range driver really does show some limitations in the upper midrange. Last I measured the Hemp it displayed a significant peak/dip in the 2.5 kHz region and another one in the 4-5 kHz area.
Personally, I am going to cross the Hemp to a cone tweeter in the near future. I guess I'll cross at 3 kHz and the reason for this is that while the breakup (I guess it's breakup) at 2.5 kHz is audible, the mess appearing at 4-5 kHz sounds the nastiest.
I think you would be well served with a tweeter handling the upper frequencies; one that does not have too wide a dispersion.
Best
Kris
tinitus,
A four way OB seems a little overkill, but may be the ribbons will supplement each other beautifully. Just what frequencies have you planned for the midrange and what unit, and similarely for the woofer part ? Are you aiming at 90 dB/1 watt sensitivity for the whole system ? And then the question of bass equalization or not ? And on the whole passive or active ? Last SUB frequencies. I think you have to go IB with those or perhaps look at the Servo Bass at Gr-Research. Many questions not perhaps in the right order.
Just to get a feel of OB performance I do recommend playing around with MJK's Math Cad models. You will learn a lot also by using the free Math Cad version. I you can't save you can copy ! The speed is, with the latest versions, dramatically improved and you will not get better predictions anywhere else. That's at least my impression having used Edge, Basta and Xlbaffle. Although Edge is useful on its own as it directly compute baffle influence, if the unit placed on the baffle is ideal.
My response is partly written because during the coming month I plan to investigate some OB projects. These will include double Eminenca Alphas in H- and U-baffle in stereo. These will be thoroughly compared to the performance of my A&D 1524 in its baffle. Upwards (in frequency) I will build baffles containing Peerless SDS-134 and Neo3 in Appolito configuration and also Monacor MS-100CHQ together with a quasi ribbon of Chinese origin that I already have. These projects are a bit on the budget side, I know thats my 'thing', but nevertheless could prove some points. I certainly will report of my doings over at AudioCircle in the OB-section.
/Erling
A four way OB seems a little overkill, but may be the ribbons will supplement each other beautifully. Just what frequencies have you planned for the midrange and what unit, and similarely for the woofer part ? Are you aiming at 90 dB/1 watt sensitivity for the whole system ? And then the question of bass equalization or not ? And on the whole passive or active ? Last SUB frequencies. I think you have to go IB with those or perhaps look at the Servo Bass at Gr-Research. Many questions not perhaps in the right order.
Just to get a feel of OB performance I do recommend playing around with MJK's Math Cad models. You will learn a lot also by using the free Math Cad version. I you can't save you can copy ! The speed is, with the latest versions, dramatically improved and you will not get better predictions anywhere else. That's at least my impression having used Edge, Basta and Xlbaffle. Although Edge is useful on its own as it directly compute baffle influence, if the unit placed on the baffle is ideal.
My response is partly written because during the coming month I plan to investigate some OB projects. These will include double Eminenca Alphas in H- and U-baffle in stereo. These will be thoroughly compared to the performance of my A&D 1524 in its baffle. Upwards (in frequency) I will build baffles containing Peerless SDS-134 and Neo3 in Appolito configuration and also Monacor MS-100CHQ together with a quasi ribbon of Chinese origin that I already have. These projects are a bit on the budget side, I know thats my 'thing', but nevertheless could prove some points. I certainly will report of my doings over at AudioCircle in the OB-section.
/Erling
Hi Michael and Kris,
Widerancge driver treble peaks can be bothersome because they beam.
I find that dispersing them, especially from the cone centre, gives opportunity to balance reproduction; as here, by using 4" hollow light foam rolls pulled off mini paint rollers after soaking them in boiling water to soften the adhesive.
Both are close to but clear of the cone, the upper one in front of a B200 de-Qs airside resonance; the lower one ditto, plus disperses HF, and is adjustable by the amount of dust-cap obscured via axial alignment.
Cost is negligible and worth a try !
Cheers ......... Graham.
Widerancge driver treble peaks can be bothersome because they beam.
I find that dispersing them, especially from the cone centre, gives opportunity to balance reproduction; as here, by using 4" hollow light foam rolls pulled off mini paint rollers after soaking them in boiling water to soften the adhesive.
Both are close to but clear of the cone, the upper one in front of a B200 de-Qs airside resonance; the lower one ditto, plus disperses HF, and is adjustable by the amount of dust-cap obscured via axial alignment.
Cost is negligible and worth a try !
Cheers ......... Graham.
Graham,
I didn't mentioned but I have also decided to give the B200 a go. By complementing it with the Monacor SP-130X/8 in the lower midrange as you have suggested, which I think is a very good idea. And perhaps also by letting the dustcap go and using your suggested 'Pinocchio' (my nameing) cornet. Did you furthered it anything yourself ? (OT I know)
/Erling
I didn't mentioned but I have also decided to give the B200 a go. By complementing it with the Monacor SP-130X/8 in the lower midrange as you have suggested, which I think is a very good idea. And perhaps also by letting the dustcap go and using your suggested 'Pinocchio' (my nameing) cornet. Did you furthered it anything yourself ? (OT I know)
/Erling
Och !
Silly me. I forgot to add the photo of the foam fingers.
I was in too much of a hurry to go and order some drivers.
Photo now attached.
Hi Erling,
Yes. The 'Pinocchio' cone was completely rechecked from a fresh start on the B200 and is definitely going to be used, but I have spent so long trying to find suitable/available 15"ers since then.
The final attachment is not fully finished, so no photo yet.
The printer paper cone is superglued to the voice coil edge with its point sticking out a further 65mm beyond the voice coil edge.
Here the rounded foam fingers are +/-25mm from the centre axis and mounted in a straight line horizontally across the front of the driver. The tip of the cone is almost level with the leading edges of the foam rolls.
Two other vertical rolls close to the main cone and set back from the protruding centre cone also by 25mm further prevent beaming.
A B200 that hardly beams ! You can move around and enjoy the music !
Do try it on your Hemps if they are without their dustcaps.
Will be able to finish this now that other the drivers are ordered.
One aspect I noted when running a widerange above 2x lower frequency drivers is that reproduction dropped out very sharply when my ears went above the axis of the widerange. (Like going beyond the range of a vertical line.)
When the widerange was between the two lower frequency drivers in D'Apollito fashion the cut-off became gradual again for both up/down movement.
This is why I have ordered 10" too, in case this needs to be used above the widerange to split the BSC share I will try leaving to the larger drivers.
Cheers ........ Graham.
Silly me. I forgot to add the photo of the foam fingers.
I was in too much of a hurry to go and order some drivers.
Photo now attached.
Hi Erling,
Yes. The 'Pinocchio' cone was completely rechecked from a fresh start on the B200 and is definitely going to be used, but I have spent so long trying to find suitable/available 15"ers since then.
The final attachment is not fully finished, so no photo yet.
The printer paper cone is superglued to the voice coil edge with its point sticking out a further 65mm beyond the voice coil edge.
Here the rounded foam fingers are +/-25mm from the centre axis and mounted in a straight line horizontally across the front of the driver. The tip of the cone is almost level with the leading edges of the foam rolls.
Two other vertical rolls close to the main cone and set back from the protruding centre cone also by 25mm further prevent beaming.
A B200 that hardly beams ! You can move around and enjoy the music !
Do try it on your Hemps if they are without their dustcaps.
Will be able to finish this now that other the drivers are ordered.
One aspect I noted when running a widerange above 2x lower frequency drivers is that reproduction dropped out very sharply when my ears went above the axis of the widerange. (Like going beyond the range of a vertical line.)
When the widerange was between the two lower frequency drivers in D'Apollito fashion the cut-off became gradual again for both up/down movement.
This is why I have ordered 10" too, in case this needs to be used above the widerange to split the BSC share I will try leaving to the larger drivers.
Cheers ........ Graham.
Attachments
Ha! The fickle fingers of foam!
I have some of those, bought them to do a very similar thing, reduce horn beaming. Never thought to use them in front of a cone driver. Brilliant!
Years ago, the first "hi-fi" line-array I ever saw had a vertical wooden rod running up and down in front of the drivers. Centered and maybe 2" off the baffle face. Was meant to help make a cylindrical wavefront. Don't know if it really worked.
Kris
Yeah, good idea on the Hemp 6.5, it's a good driver. Have thought about using it myself. Having been able to directly compare the Hemp 4.5, 6.5 and 8" over a period of several days - the 6.5 is my favorite. A lot of people like the 4.5, better, tho.
Whizzer cone drivers are notoriously hard to measure, so be careful there. But if you don't like what you're hearing, then you can trust that.
I have some of those, bought them to do a very similar thing, reduce horn beaming. Never thought to use them in front of a cone driver. Brilliant!
Years ago, the first "hi-fi" line-array I ever saw had a vertical wooden rod running up and down in front of the drivers. Centered and maybe 2" off the baffle face. Was meant to help make a cylindrical wavefront. Don't know if it really worked.
Kris
Yeah, good idea on the Hemp 6.5, it's a good driver. Have thought about using it myself. Having been able to directly compare the Hemp 4.5, 6.5 and 8" over a period of several days - the 6.5 is my favorite. A lot of people like the 4.5, better, tho.
Whizzer cone drivers are notoriously hard to measure, so be careful there. But if you don't like what you're hearing, then you can trust that.
nickmckinney said:
Sorry for digging up the old post. The quoted paragraph above is in page 1, post #13.
The statement about low inductance of woofer makes me think of Peavey. I remeber their woofers tend to have less inductance than other equivilants.
For example:
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=294-311
http://www.partsexpress.com/pdf/294-309s.pdf
0.336mH for a 15"er is indeed very low inductance. However I don't remember any special words about this from Peavey?
On paper, the Peavey seem pretty good (to me), but they are not so popular around this DIY community. I don't remember any DIY projects using them.
Any inputs?
CLS said:
Sorry for digging up the old post. The quoted paragraph above is in page 1, post #13.
The statement about low inductance of woofer makes me think of Peavey. I remeber their woofers tend to have less inductance than other equivilants.
For example:
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=294-311
http://www.partsexpress.com/pdf/294-309s.pdf
0.336mH for a 15"er is indeed very low inductance. However I don't remember any special words about this from Peavey?
On paper, the Peavey seem pretty good (to me), but they are not so popular around this DIY community. I don't remember any DIY projects using them.
Any inputs?
Low inductance is just one indicator, you can also get low inductance with having a small coil and/or larger clearance in the gap and/or skinny T shape pole piece.
Looking at this driver it has 0.336mH with 1.9mm xmax vs a TD15X with ~0.26mH and ~16mm xmax. You can see the TD has to get its low inductance from a massive Faraday Ring.
skorpion said:
I started the project many years ago to save money, and I didnt know you guys and all your good ideas, I didnt even have a computer
Now I just want to finish the project fore the fun of it
I made a 200liter closed box fore a 15" years ago
Now I think I will do a dipole bass as well and use the closed box fore a high power system
The 2 ribbons will be 220x15mm and 100x8mm, XO points 1000hz/10khz
The 6" midwoofer is also DIY
Ribbons and midwoofer will be mounted on the same baffle and will be without actual chassis
I have no quest fore sub frequencies or high SPL, just nice sound at moderate SPL ... yeah I know there would be easier ways fore that
Attachments
CLS said:
The Peavey more than double the voice coil clearance in the gap compared to the Lambda TD15M. Its magnetic outer plate is probably half as thick, and the inner pole was a matching T pole from what I remember of them (meaning some of the voice coil is air cored rather than steel cored). I don't remember the winding height of the voice coil but I would say its around 12-17mm at most.
I have reconed/rebuilt quite a few of them for burnt voice coils.
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