Derek, I am afraid but I think your definition of „pistonic“ doesn’t match with what >99% of people (including me) define as pistonic behaviour.
Pistonic behaviour is when all points of a cone move in the same direction and at the same velocity etc at the same instant. Non - pistonic is when there is cone breakup – and this has absolutely nothing to do with the damped mass-spring system behaviour that you describe. Those are a different kettle of fish.
Your driver-at-100mph experiment is a little far fetched:
Wiuth a loudspeaker used as intended you don’t have a whole driver in an airstream (including the magnet and basket which will significantly influence drag in your experiment !!!!) but a stationary driver whose cone is moving.
And then there come the numbers: Your 100 mph is about 40 m/s. If you have a cone that is moving 40 mm peak-to-peak at 40 Hz, which is quite much (intentionally chosen), then we would have a peak cone velocity of 10 m/s approx. So we can say that at practical average cone excursions your 100 mph experiment is off by about one order of magnitude at least.
And no, there is no need for a statement that starts with : “ But at higher frequencies……… !” No - cone velocity will not be increased, it will actually be decreased for a given amount of acoustic power and increasing frequency !
And yes, drivers with a lot of SD are getting non - pistonic at lower frequencies than small ones !
Regards
Charles
Pistonic behaviour is when all points of a cone move in the same direction and at the same velocity etc at the same instant. Non - pistonic is when there is cone breakup – and this has absolutely nothing to do with the damped mass-spring system behaviour that you describe. Those are a different kettle of fish.
Your driver-at-100mph experiment is a little far fetched:
Wiuth a loudspeaker used as intended you don’t have a whole driver in an airstream (including the magnet and basket which will significantly influence drag in your experiment !!!!) but a stationary driver whose cone is moving.
And then there come the numbers: Your 100 mph is about 40 m/s. If you have a cone that is moving 40 mm peak-to-peak at 40 Hz, which is quite much (intentionally chosen), then we would have a peak cone velocity of 10 m/s approx. So we can say that at practical average cone excursions your 100 mph experiment is off by about one order of magnitude at least.
And no, there is no need for a statement that starts with : “ But at higher frequencies……… !” No - cone velocity will not be increased, it will actually be decreased for a given amount of acoustic power and increasing frequency !
And yes, drivers with a lot of SD are getting non - pistonic at lower frequencies than small ones !
Regards
Charles
Manger motor
Hi CV and Phase Accurate,
I think there is scope to greatly increase the Bl factor, the twin voice coils & gap engineering are such a work of art I would not want to mess with them, so it all must come from a "mother of a magnet"
I suspect a redesign for the basket would be required.
This will bring the added benefit of improved ventilation to cool the voice coils and reduce rear wave reflections.
I know very little about the engineering involved with field coil motors so maybe someone else could help here?
Phase accurate,
You raise some good points and Will reply in detail when I have a little more time.
Suffice to say I do 100% stand by the gross oscillation errors inherent in most drivers.
The name "pistonic" and its definition are a side issue, and not in dispute.
What I am trying to point out is that while driver designers are placing all the emphasis on the cone area attempting to remain pistonic in relation to itself i.e. as you point out all parts of the cone pistonic to itself. The real problem is the whole "pistonic cone" is grossly distorting the wave launch and decay!
On the speed of cone movement and the 100mph car analogy I was going to extreme, too extreme as you correctly point out to highlight the point. Again I will update this when I have some more time.
Thanks for opening this debate on what I believe is a huge and underestimated design issue.
Some of the best ways to reduce this "ghost echo" effect are also the best ways to minimise Thermal Compression which has just been brought to my attention by the quite brilliant Michael Gerstgrasser, Thanks Michael!
And Thanks to Phase accurate for opening this debate on what I believe is a greatly underestimated design issue with 99% of all drivers.
All the best
Derek.
Hi CV and Phase Accurate,
I think there is scope to greatly increase the Bl factor, the twin voice coils & gap engineering are such a work of art I would not want to mess with them, so it all must come from a "mother of a magnet"
I suspect a redesign for the basket would be required.
This will bring the added benefit of improved ventilation to cool the voice coils and reduce rear wave reflections.
I know very little about the engineering involved with field coil motors so maybe someone else could help here?
Phase accurate,
You raise some good points and Will reply in detail when I have a little more time.
Suffice to say I do 100% stand by the gross oscillation errors inherent in most drivers.
The name "pistonic" and its definition are a side issue, and not in dispute.
What I am trying to point out is that while driver designers are placing all the emphasis on the cone area attempting to remain pistonic in relation to itself i.e. as you point out all parts of the cone pistonic to itself. The real problem is the whole "pistonic cone" is grossly distorting the wave launch and decay!
On the speed of cone movement and the 100mph car analogy I was going to extreme, too extreme as you correctly point out to highlight the point. Again I will update this when I have some more time.
Thanks for opening this debate on what I believe is a huge and underestimated design issue.
Some of the best ways to reduce this "ghost echo" effect are also the best ways to minimise Thermal Compression which has just been brought to my attention by the quite brilliant Michael Gerstgrasser, Thanks Michael!
And Thanks to Phase accurate for opening this debate on what I believe is a greatly underestimated design issue with 99% of all drivers.
All the best
Derek.
The decay problem can be much reduced by the use of well damped closed box (what is intrinsic to you high-BL drivers) or open-baffle tuning combined with phase_accurate crossovers. This is not very new knowledge.
I think I does not necessarily have to be a Manger driver to achieve this. If done correctly you could as well use conventional drivers in a multi-way arrangement. It just depends on HOW it is done.
Regards
Charles
crossovers. This is not very new knowledge.I think I does not necessarily have to be a Manger driver to achieve this. If done correctly you could as well use conventional drivers in a multi-way arrangement. It just depends on HOW it is done.
Regards
Charles
Pistonic motion & Driver speed
Hi Charles,
Sorry about the delay with my reply, I have twin 18 month old boys and my 6 year old daughter is on Easter holidays so home is a busy place right now!
It would appear that my views on driver motion and driver speed are a bit controversial....!
I have a few posts on three different threads and I dont want to go of topic on other guys threads so I am going to start a new thread on this subject.
It will take me a few days to collate all the info and cut n paste them into an order of sorts.
I do hope you can add your valuable experience and opinions
As Winston Churchill once said " I may disagree with your opinion, but I will defend your right to express that opinion with my last breath!" Long live democratic debate!
All the best
Derek.
Hi Charles,
Sorry about the delay with my reply, I have twin 18 month old boys and my 6 year old daughter is on Easter holidays so home is a busy place right now!
It would appear that my views on driver motion and driver speed are a bit controversial....!
I have a few posts on three different threads and I dont want to go of topic on other guys threads so I am going to start a new thread on this subject.
It will take me a few days to collate all the info and cut n paste them into an order of sorts.
I do hope you can add your valuable experience and opinions
As Winston Churchill once said " I may disagree with your opinion, but I will defend your right to express that opinion with my last breath!" Long live democratic debate!
All the best
Derek.
Hi Derek,
I am no expert on the subject of motion / speed / or stored energy.
A few years ago, I read a paper on the AdireAudio site that explained limiting factors of a drive units speed:
http://www.diycable.com/main/pdf/WooferSpeed.pdf
Regards,
AJ
I am no expert on the subject of motion / speed / or stored energy.
A few years ago, I read a paper on the AdireAudio site that explained limiting factors of a drive units speed:
http://www.diycable.com/main/pdf/WooferSpeed.pdf
Regards,
AJ
Hi AJ ,
I have just been posting a little bit on this very article on StigErik's
thread about his superb new speaker project using two Beyma drivers and a Seas mid driver.
I have copied it below as it applies to our Manger projects as well.
""Hi Scott and StigErik,
Scott,
Thanks for the links to the old Adire article on driver speed, I read them with interest years ago after I met Dan at a CES or Denver show about 5 years ago.
I was sad to see the demise of Lambda and Adire.
Dan and John are indeed very clever driver designers and I have great respect for their new Acoustic Elegance drivers, I hope to have a chance to evaluate a pair of TD12M drivers soon.
Interesting that their new flagship drivers (TD 12 M & TD15M ) feature ultra low Mms to high Bl ratio's….!
50g over 17Bl = 2.94 for the TD12M one of the lowest Mms to Bl ratios of ANY Pro 12 inch driver.
Ditto the TD15M 70g over 17 Bl a great figure of 4.1, most 15 inch pro drivers are in the 5 or 6 bracket.
Maybe they have come around to my way of thinking….!
I first published my theory on this subject on my website in Jan 2005….
I am in full agreement with Dan and Nick that the lowest possible inductance is a valuable goal and will reduced stored energy therefore increase speed & lower distortion.
BUT, that is not the whole story, not even the most important chapter...! This is a very important subject, it was in my opinion THE most important issue in driver design until last week when MG sent me his Thermal Compression white paper...!
I don’t want to go off topic on this thread so I will start a new thread on driver design. I will put forward my views on the Mms to Bl ratio, the importance of low VC inductance, thermal compression (hopefully with the help of Michael Gerstgrasser!) aerodynamics, efficiency, power handling and materials.
That should be a good "cat among the pigeons"
StigErik,
The Beyma 18G50 (not the 18G550) is a very fast driver: Mms170g over Bl of 28.8 = 5.9. Great result for an 18 inch power house pro driver.
The 15 inch SM 115 K I am using = 5.1,(17% "better" ) but your 18 inch has 50% greater Sd therefore only has to travel 50% as far for the same Vd so your 18 G50 is actually 33% faster than the smaller and lighter SM115K!
The 18 G50 is a great open baffle driver and I would be Oh so interested to see how the measurements compare and more importantly how the sound quality compares to the 21 inch Beyma driver. Again Plleeeese post the measurements!
My point is that only in a "like for like" ie same Sd for same Sd, the lower the ratio the faster the driver. This assumes all other parameters being equal (Efficiency, Thermal compression, VC Le, etc) which they never are...!
All the best
Derek.""
I have just been posting a little bit on this very article on StigErik's
thread about his superb new speaker project using two Beyma drivers and a Seas mid driver.
I have copied it below as it applies to our Manger projects as well.
""Hi Scott and StigErik,
Scott,
Thanks for the links to the old Adire article on driver speed, I read them with interest years ago after I met Dan at a CES or Denver show about 5 years ago.
I was sad to see the demise of Lambda and Adire.
Dan and John are indeed very clever driver designers and I have great respect for their new Acoustic Elegance drivers, I hope to have a chance to evaluate a pair of TD12M drivers soon.
Interesting that their new flagship drivers (TD 12 M & TD15M ) feature ultra low Mms to high Bl ratio's….!
50g over 17Bl = 2.94 for the TD12M one of the lowest Mms to Bl ratios of ANY Pro 12 inch driver.
Ditto the TD15M 70g over 17 Bl a great figure of 4.1, most 15 inch pro drivers are in the 5 or 6 bracket.
Maybe they have come around to my way of thinking….!
I first published my theory on this subject on my website in Jan 2005….
I am in full agreement with Dan and Nick that the lowest possible inductance is a valuable goal and will reduced stored energy therefore increase speed & lower distortion.
BUT, that is not the whole story, not even the most important chapter...! This is a very important subject, it was in my opinion THE most important issue in driver design until last week when MG sent me his Thermal Compression white paper...!
I don’t want to go off topic on this thread so I will start a new thread on driver design. I will put forward my views on the Mms to Bl ratio, the importance of low VC inductance, thermal compression (hopefully with the help of Michael Gerstgrasser!) aerodynamics, efficiency, power handling and materials.
That should be a good "cat among the pigeons"
StigErik,
The Beyma 18G50 (not the 18G550) is a very fast driver: Mms170g over Bl of 28.8 = 5.9. Great result for an 18 inch power house pro driver.
The 15 inch SM 115 K I am using = 5.1,(17% "better" ) but your 18 inch has 50% greater Sd therefore only has to travel 50% as far for the same Vd so your 18 G50 is actually 33% faster than the smaller and lighter SM115K!
The 18 G50 is a great open baffle driver and I would be Oh so interested to see how the measurements compare and more importantly how the sound quality compares to the 21 inch Beyma driver. Again Plleeeese post the measurements!
My point is that only in a "like for like" ie same Sd for same Sd, the lower the ratio the faster the driver. This assumes all other parameters being equal (Efficiency, Thermal compression, VC Le, etc) which they never are...!
All the best
Derek.""
Hi Derek,
Interestingly, you seem to both agree with the Adire article (which dismisses both Mms and BL as being irelevant to the transient response) AND consider Mms/BL ratio as relevant for a driver's "speed" ?
To me, the Adire article has a major flaw. It says:
BLi = ma
Interesting! This says that the change in acceleration of a driver - how fast it can change position - is
strictly a function of the current through the driver. In fact, if you could make the current change infinitely
fast, then the driver would accelerate infinitely fast, and we'd have infinite transients - zero time to change
between states.
Sure, if you can make the current variate infinitely fast you would have infinite transients and the B,L,m constants would not matter. But this holds only for INFINITE: if the current variates finitely fast(as it always does in the real world) the variation of acceleration corresponding to a change in the current would be PROPORTIONAL to -guess what ? - BL/m !
I have, OTOH, some understanding trouble on another post of yours:
My actual understanding problem with what you said is why you seem to see the "root of all evil" as being the mass/spring paradigm and it's "pistonic"(in the generally accepted meaning of all points of the surface moving in the same direction) motion ?
I mean, what else is there ? Virtually all sound radiators are mass suspended on some sort of spring, right (a notable exception being the driver that gives the title to this thread, but how about bass) ?
I am waiting with great interest your follow ups on your opinions about this stuff!
Overkill Audio said:
Interestingly, you seem to both agree with the Adire article (which dismisses both Mms and BL as being irelevant to the transient response) AND consider Mms/BL ratio as relevant for a driver's "speed" ?
To me, the Adire article has a major flaw. It says:
BLi = ma
Interesting! This says that the change in acceleration of a driver - how fast it can change position - is
strictly a function of the current through the driver. In fact, if you could make the current change infinitely
fast, then the driver would accelerate infinitely fast, and we'd have infinite transients - zero time to change
between states.
Sure, if you can make the current variate infinitely fast you would have infinite transients and the B,L,m constants would not matter. But this holds only for INFINITE: if the current variates finitely fast(as it always does in the real world) the variation of acceleration corresponding to a change in the current would be PROPORTIONAL to -guess what ? - BL/m !
I have, OTOH, some understanding trouble on another post of yours:
Your analogy seems to suggest that the ball(mass/spring system) is oscilating freely out of control after it has been applied an impulse - which as I am sure you know is simply not the case: the movement should be further controlled by the voice coil current/motor - but I am sure I don't need to tell you that.
My actual understanding problem with what you said is why you seem to see the "root of all evil" as being the mass/spring paradigm and it's "pistonic"(in the generally accepted meaning of all points of the surface moving in the same direction) motion ?
I mean, what else is there ? Virtually all sound radiators are mass suspended on some sort of spring, right (a notable exception being the driver that gives the title to this thread, but how about bass) ?
I am waiting with great interest your follow ups on your opinions about this stuff!
Without knowing much about the Manger
But looking at it realistically, and at the way it works mechanically, I suppose that fore a theoretical optimum result I would use it as a low crossed tweeter, crossed in the neighbourhood of 1khz
Best woofer fore that would most likely be a 6.5"
Or maybe a fullrange/widerange of some kind
I know its provocative, but no joke
Have it ever been tried, I havent heard about it
But looking at it realistically, and at the way it works mechanically, I suppose that fore a theoretical optimum result I would use it as a low crossed tweeter, crossed in the neighbourhood of 1khz
Best woofer fore that would most likely be a 6.5"
Or maybe a fullrange/widerange of some kind
I know its provocative, but no joke
Have it ever been tried, I havent heard about it
Driver behaviour, pistonic or oscillation?
Hi Guys,
Just to say I have posted an edited version of my "pistonic or oscillation" driver theory in a new thread to avoid going off topic here.
On the Manger bass driver topic here I have a few replies to catch up on so apologies for the delay to all.
DIAR & tinitus,
Yes Precision Devices are great drivers and your 15 inch unit is a real sweety! Have you seen the great work over at www.humblehomemadehifi.com ?
Check out his serious sub, two 21 inch Precision Device drivers.....!!!! And I thought I was Mr Overkill, I am humbled!
Very interesting if you read his detailed reports, the Open Baffle or U frame was his number 1 choice for the absolute best bass sound quality. He only chose to go sealed box to get maximum Home Cinema coverage. Very interesting.
Hey tinitus,
Is 6.5 inch a woofer...? Please give me a 10incher at least! The Volt BM2500.4 in a 40 litre sealed box or the 15 inch Beyma SM115K in an open baffle, they both rock with the Manger.
I can see where you are coming from but you need at least 300 Sd to have any real SPL, dynamics and minimum excursion, with low distortion. As soon as you ask a wee driver to start pumping plus / minus 5mm or 6mm you are in trouble.
bzfcocon,
Please re-read my previous post, I spell out that I am clearly NOT in agreement with Dan and Nick at Adire audio! I do agree with you! Also if you go to my new thread titled "driver behaviour, pistonic or oscillation" you will more detail on this VERY IMPORTANT subject.
Please do come back to me as I am very interested in your energy equation based approach, its the only way to go!
Phase-accurate,
There is no advantage in crossing over the Manger above 400Hz as the excursion is minimal at 400Hz and above. You still keep 80% of the point source / time coherence magic at 400Hz. If you crossover at 1,000Hz you are better off using the amazing new Beyma TPL AMT derivative. The TPL is going to wipe out 90%- of all high end ribbons, domes, and compression drivers, the TPL is stunning.
How about the TPL driver in a wave guide / baffle, crossing it over at 1,800Hz to a 12 or 15 inch driver down to 80 Hz then using 2 or 3 sealed subs in corners all controlled with a DSP crossover / room correction i.e. DEQX?
All the best
Derek.
Hi Guys,
Just to say I have posted an edited version of my "pistonic or oscillation" driver theory in a new thread to avoid going off topic here.
On the Manger bass driver topic here I have a few replies to catch up on so apologies for the delay to all.
DIAR & tinitus,
Yes Precision Devices are great drivers and your 15 inch unit is a real sweety! Have you seen the great work over at www.humblehomemadehifi.com ?
Check out his serious sub, two 21 inch Precision Device drivers.....!!!! And I thought I was Mr Overkill, I am humbled!
Very interesting if you read his detailed reports, the Open Baffle or U frame was his number 1 choice for the absolute best bass sound quality. He only chose to go sealed box to get maximum Home Cinema coverage. Very interesting.
Hey tinitus,
Is 6.5 inch a woofer...? Please give me a 10incher at least! The Volt BM2500.4 in a 40 litre sealed box or the 15 inch Beyma SM115K in an open baffle, they both rock with the Manger.
I can see where you are coming from but you need at least 300 Sd to have any real SPL, dynamics and minimum excursion, with low distortion. As soon as you ask a wee driver to start pumping plus / minus 5mm or 6mm you are in trouble.
bzfcocon,
Please re-read my previous post, I spell out that I am clearly NOT in agreement with Dan and Nick at Adire audio! I do agree with you! Also if you go to my new thread titled "driver behaviour, pistonic or oscillation" you will more detail on this VERY IMPORTANT subject.
Please do come back to me as I am very interested in your energy equation based approach, its the only way to go!
Phase-accurate,
There is no advantage in crossing over the Manger above 400Hz as the excursion is minimal at 400Hz and above. You still keep 80% of the point source / time coherence magic at 400Hz. If you crossover at 1,000Hz you are better off using the amazing new Beyma TPL AMT derivative. The TPL is going to wipe out 90%- of all high end ribbons, domes, and compression drivers, the TPL is stunning.
How about the TPL driver in a wave guide / baffle, crossing it over at 1,800Hz to a 12 or 15 inch driver down to 80 Hz then using 2 or 3 sealed subs in corners all controlled with a DSP crossover / room correction i.e. DEQX?
All the best
Derek.
Re: Driver behaviour, pistonic or oscillation?
Well, I only thought of maximum sound quality at moderate SPL
If Im not completely mistaken, the Manger is rated at 25watt only
Doesnt look like a driver I would use if the goal was dynamical high SPL
I would expect power compression to set in quite early, so I do not see any sense in big pro drivers, as much as I would like to use them
Maybe better think of a driver like Supravox 215GMF
Only, its a 97db driver
Going active or just biamp would solve that
But high Fs, which is a compromise
Unless using subs
The working principle of Manger, with its planar like and highly waveform flexing diaphragm, points in the direction of moderate SPL
At least thats how it looks to me
That could also be an indication why it doesnt seem to work with hard coned woofers
Overkill Audio said:
Well, I only thought of maximum sound quality at moderate SPL
If Im not completely mistaken, the Manger is rated at 25watt only
Doesnt look like a driver I would use if the goal was dynamical high SPL
I would expect power compression to set in quite early, so I do not see any sense in big pro drivers, as much as I would like to use them
Maybe better think of a driver like Supravox 215GMF
Only, its a 97db driver
Going active or just biamp would solve that
But high Fs, which is a compromise
Unless using subs
The working principle of Manger, with its planar like and highly waveform flexing diaphragm, points in the direction of moderate SPL
At least thats how it looks to me
That could also be an indication why it doesnt seem to work with hard coned woofers
Manger bass
Hi Tinitus,
Sure thing at low to moderate spl a medium sized fast bass driver will be really good with the Manger.
I have no experience with the Supravox and as you say the high Fs will limit the low end a bit, but hey good bass to 50Hz or 60 Hz is better than poor bass all the way!
It tends to really annoy people when say that most people have never heard the Manger because they (a) cross it over to low or (b) use a passive crossover or (c) both!
Buts its true!
Ignore the paper spec and 99% of all the Manger Zero box clones
on the DIY scene. When used correctly the Manger can blow you away at 25 feet with astonishing dynamics.
You can pour in 200watts to 400 watts of real solid state power(no mushy passive crossover full of resistors to "protect" the Manger) and get lifelike low distortion music.
On the power compression front....the Manger has TWIN 75mm voice coils inside, alligned in the tighest tolerance gap of any driver in production. How many 8 inch low mid drivers have 1 75mm VC never mind 2....?!!
Used open baffle above 400Hz your ears will compress before this baby!
Or you can also use it gently as an ultra pure genuine point source from 200Hz up active or passive at medium and low SPL and it will melt your heart.
Its a great pice of kit!
All the best
Derek.
Hi Tinitus,
Sure thing at low to moderate spl a medium sized fast bass driver will be really good with the Manger.
I have no experience with the Supravox and as you say the high Fs will limit the low end a bit, but hey good bass to 50Hz or 60 Hz is better than poor bass all the way!
It tends to really annoy people when say that most people have never heard the Manger because they (a) cross it over to low or (b) use a passive crossover or (c) both!
Buts its true!
Ignore the paper spec and 99% of all the Manger Zero box clones
on the DIY scene. When used correctly the Manger can blow you away at 25 feet with astonishing dynamics.
You can pour in 200watts to 400 watts of real solid state power(no mushy passive crossover full of resistors to "protect" the Manger) and get lifelike low distortion music.
On the power compression front....the Manger has TWIN 75mm voice coils inside, alligned in the tighest tolerance gap of any driver in production. How many 8 inch low mid drivers have 1 75mm VC never mind 2....?!!
Used open baffle above 400Hz your ears will compress before this baby!
Or you can also use it gently as an ultra pure genuine point source from 200Hz up active or passive at medium and low SPL and it will melt your heart.
Its a great pice of kit!
All the best
Derek.
Did not know where to ask but here, sorry if it's OT: has anyone tried the Manger Holoprofile:
http://www.manger-msw.de/index.php?language=en&pid=ix5XOw4qBMO4aiMlOubPE1u7rPsIXPpf&country=
And if yes, does it hold what it promisses ?
To me, the theory and explanation are somewhat questionable given the Haas effect which should mask the sound emmited by the far half of the source, but I am really no expert.
I do vaguely remember another explanation of the stereo image collapse based on the polar response and I belive there are some loudspeakers out there taking this into account.
http://www.manger-msw.de/index.php?language=en&pid=ix5XOw4qBMO4aiMlOubPE1u7rPsIXPpf&country=
And if yes, does it hold what it promisses ?
To me, the theory and explanation are somewhat questionable given the Haas effect which should mask the sound emmited by the far half of the source, but I am really no expert.
I do vaguely remember another explanation of the stereo image collapse based on the polar response and I belive there are some loudspeakers out there taking this into account.
hi all
derek id love if you could give some more tips on your ob vpl setups
do you feel this method would allow us to use drivers for ob bass that arent traditionaly thought of as suitable for ob
do you have any general rules with this method like cutout size , front to back depth and such ,for the wings ect and any recomendations for using the mangers in this way
my current cabs house 1x scan 25w/8565 in each sealed with 80l volume 900mm hieght and 270mm width
id like to mount the mangers on top of these cabs in one of your vpl frames ,any tips would really be appreciated .id have to keep the baffle width the same though (270mm) to match the bass cabs
ive got easy access to a shop that supplies and laser cuts acrylic sheet as well so id do the manger vpl in this
regards sheafer
derek id love if you could give some more tips on your ob vpl setups
do you feel this method would allow us to use drivers for ob bass that arent traditionaly thought of as suitable for ob
do you have any general rules with this method like cutout size , front to back depth and such ,for the wings ect and any recomendations for using the mangers in this way
my current cabs house 1x scan 25w/8565 in each sealed with 80l volume 900mm hieght and 270mm width
id like to mount the mangers on top of these cabs in one of your vpl frames ,any tips would really be appreciated .id have to keep the baffle width the same though (270mm) to match the bass cabs
ive got easy access to a shop that supplies and laser cuts acrylic sheet as well so id do the manger vpl in this
regards sheafer
Manger ideas.
Hi Sheafer,
I have sent a few photos to Telstar of my last Manger VPL test cabinets which I have not had time to work on recently.
The photos are too big to post on the forum but if you private email me I will send them to you and you can shrink them down and post them if you want.
The calculations for exact baffle width / side depth / scallop shape cut out are all dependant on driver bandwidth, Fs, Sd and power handling. Surprisingly Qts is almost irrelevant!
I only started posting all this stuff recently as I was keeping my options open to sell it commercially but I will never have the time to get back into all that.
If you read through my posts over the last few weeks and look at the photographs you will get 80% of what you need to build a good open baffle VPL system.
A few golden rules are :
Avoid cabinet symmetry, Variable Path Length cancellation with the more variety the better!
The Manger only needs a relatively small baffle to go down to 300Hz or 400Hz. Trapezoid is best, circular is worst, everything else in between.
If using a traditional OB where the drivers are supported on the baffle, use heavy baffle, light weight sides, medium weight top, heavy base if using a base..
Fine tune the scallop cut outs using trial and error "Foamex" or hardboard. The Fibre board for underneath hard wood floors is great when PVA glued to Foamex or even hardboard.
You don't need a speaker base but a smooth base lets you easily slide the speakers in and out so you can have them against the wall for background listening and 1.2m out for serious fun!
One eternal compromise in a two way is you want the bass / low mid as close to the floor for bass reinforcement and avoiding floor bounce artefacts. But you want it as close to the Manger as poss to minimise vocal and instrumental smearing at 300Hz t0 400Hz.
A three way solves the worst of this with the help of a big soft rug in front of the speakers. Always mount the bass driver as close to the floor as poss if using 3 way.
Three way is best as it will greatly reduce thermal compression.
The real problem with all Scanspeak, Seas, Peerless etc is the tiny voice coils and often medium to heavy cones. A Manger combined with the 10 inch Volt 2500.4 (both drivers VPL) with its 3 inch voice coil, linen surround and light weight cone will blow away ANY audiophile / Hifi driver(s) including all the specialist large bandwidth "full range" drivers at any price.
You will never get good results out of sealed bass paired with open baffle Manger.
Try reading the great info from StigErik on his fantastic Beyma TPL open baffle thread. Go open baffle all the way! Let nature take its course!!
If staying two way you will need at least two 10 inch drivers (Seas or Scanspeak) per side in an open baffle to get acceptably low distortion bass / low mid.
My very strongest recommendation is to keep the 10 inch Scanspeaks you have and use them (one each side) to cover the 100Hz to 300hz or 400Hz crossover point to your Mangers. This will greatly reduce the Thermal Compression that they will otherwise suffer from, big time!
Now buy a pair of the best value for money drivers around, the beyma SM 115K 15 inch bass drivers and run them open baffle from 100Hz down. Awesome combination trust me, please, build it and they will come!!
Forget all passive crossover for this design, if funds are tight use a Xilica DSP crossover, try upgrading the power supply to a battery supply.
If you can afford it buy a DEQX, again when funds allow upgrade the power supply to a battery supply. Lastly get 3 stereo ESS 32 Bit DAC's (twisted pear audio) and the digi out board option for the DEQX and you have it all!!!
Once you decide what drivers you are going to use let me know and I will work out the best dimensions for your baffle / VPL sides.
Good luck!
Cheers
Derek.
Hi Sheafer,
I have sent a few photos to Telstar of my last Manger VPL test cabinets which I have not had time to work on recently.
The photos are too big to post on the forum but if you private email me I will send them to you and you can shrink them down and post them if you want.
The calculations for exact baffle width / side depth / scallop shape cut out are all dependant on driver bandwidth, Fs, Sd and power handling. Surprisingly Qts is almost irrelevant!
I only started posting all this stuff recently as I was keeping my options open to sell it commercially but I will never have the time to get back into all that.
If you read through my posts over the last few weeks and look at the photographs you will get 80% of what you need to build a good open baffle VPL system.
A few golden rules are :
Avoid cabinet symmetry, Variable Path Length cancellation with the more variety the better!
The Manger only needs a relatively small baffle to go down to 300Hz or 400Hz. Trapezoid is best, circular is worst, everything else in between.
If using a traditional OB where the drivers are supported on the baffle, use heavy baffle, light weight sides, medium weight top, heavy base if using a base..
Fine tune the scallop cut outs using trial and error "Foamex" or hardboard. The Fibre board for underneath hard wood floors is great when PVA glued to Foamex or even hardboard.
You don't need a speaker base but a smooth base lets you easily slide the speakers in and out so you can have them against the wall for background listening and 1.2m out for serious fun!
One eternal compromise in a two way is you want the bass / low mid as close to the floor for bass reinforcement and avoiding floor bounce artefacts. But you want it as close to the Manger as poss to minimise vocal and instrumental smearing at 300Hz t0 400Hz.
A three way solves the worst of this with the help of a big soft rug in front of the speakers. Always mount the bass driver as close to the floor as poss if using 3 way.
Three way is best as it will greatly reduce thermal compression.
The real problem with all Scanspeak, Seas, Peerless etc is the tiny voice coils and often medium to heavy cones. A Manger combined with the 10 inch Volt 2500.4 (both drivers VPL) with its 3 inch voice coil, linen surround and light weight cone will blow away ANY audiophile / Hifi driver(s) including all the specialist large bandwidth "full range" drivers at any price.
You will never get good results out of sealed bass paired with open baffle Manger.
Try reading the great info from StigErik on his fantastic Beyma TPL open baffle thread. Go open baffle all the way! Let nature take its course!!
If staying two way you will need at least two 10 inch drivers (Seas or Scanspeak) per side in an open baffle to get acceptably low distortion bass / low mid.
My very strongest recommendation is to keep the 10 inch Scanspeaks you have and use them (one each side) to cover the 100Hz to 300hz or 400Hz crossover point to your Mangers. This will greatly reduce the Thermal Compression that they will otherwise suffer from, big time!
Now buy a pair of the best value for money drivers around, the beyma SM 115K 15 inch bass drivers and run them open baffle from 100Hz down. Awesome combination trust me, please, build it and they will come!!
Forget all passive crossover for this design, if funds are tight use a Xilica DSP crossover, try upgrading the power supply to a battery supply.
If you can afford it buy a DEQX, again when funds allow upgrade the power supply to a battery supply. Lastly get 3 stereo ESS 32 Bit DAC's (twisted pear audio) and the digi out board option for the DEQX and you have it all!!!
Once you decide what drivers you are going to use let me know and I will work out the best dimensions for your baffle / VPL sides.
Good luck!
Cheers
Derek.
Nice information Derek.
What about using the AE TD15H woofer: http://aespeakers.com/drivers.php?driver_id=10 (gives max 103db at 50hz)?
Aurasound can also be a good option. Currently I use the NS12-513-4A in 2,5 way with a B&G Neo8PDR. 2 Aura's per channel (one up to 600hz, the other 150hz). They manage to follow the planars well, so maybe also an option for the Manger? (Or else the NS15-992-4A or NS18-992-4A)
What about using the AE TD15H woofer: http://aespeakers.com/drivers.php?driver_id=10 (gives max 103db at 50hz)?
Aurasound can also be a good option. Currently I use the NS12-513-4A in 2,5 way with a B&G Neo8PDR. 2 Aura's per channel (one up to 600hz, the other 150hz). They manage to follow the planars well, so maybe also an option for the Manger? (Or else the NS15-992-4A or NS18-992-4A)