cool looking monitor .... with a mid dome
funny, but i was actually thinking about suggesting a pro/studio woofer crossed higher ... hmm
Heh-heh, I like the PS, Andy - I've been having a similar problem but in my case its largely due to very slow typing...
Thanks for the thoughts on SPL; I realise its all down to personal taste but as long as I'm not aiming far too high, I'd rather have a margin for safety. After all the time, effort and money I'll be sinking into this it would be sad to then be unhappy with something as basic as the volume.
Cheers
kev
Thanks for the thoughts on SPL; I realise its all down to personal taste but as long as I'm not aiming far too high, I'd rather have a margin for safety. After all the time, effort and money I'll be sinking into this it would be sad to then be unhappy with something as basic as the volume.
Cheers
kev
Possibly this sort of thing may be contributing to my concern about not under-doing it. In the distant past I helped out with a bit of live music from time to time, and the power and dynamic range of even quite modest studio/PA sound systems seemed to achieve a very 'real world' quality to the sound, even if not always of the highest fidelity.cool looking monitor .... with a mid dome
funny, but i was actually thinking about suggesting a pro/studio woofer crossed higher ... hmm
On this occasion I'll only ever be playing pre-recorded music or film tracks and I definitely want hi-fi speakers. But I'd like them not to be lacking a decent bit of kick if and when the recordings ask for it.
Cheers
kev
Thanks, you're right that inspiration would be most useful; I'll look at the principles involved in those designs and see if I can learn anything. But maybe tomorrow; its heading towards my bed-time here.
Cheers
Kev
Hi Kev, I was just thinking whether you had been factoring in baffle step comp, did a quick search and saw that Face raised it early on.
I'd suggest that you should download one of the baffle step simulation progs, such as "the Edge" Jeff Bagby's spreadsheet based app, or BDS from the FRD consortium. The edge is probably the easiest choice.
If you cross over around the baffle step frequency you can probably get away with just bumping up the gain on the woofer amp, however you will be losing efficiency below the baffle step frequency. You probably should be allowing for a minimum of 3db loss (which would fit with your 105db if you max out at 108db)
The baffle geometry will affect your crossover so it is worth getting familiar with it's role in the whole design process.
Placement of the speakers will have an effect as well, if the speakers will be quite a long way from the wall you may need more than 3db of compensation.
Tony.
I'd suggest that you should download one of the baffle step simulation progs, such as "the Edge" Jeff Bagby's spreadsheet based app, or BDS from the FRD consortium. The edge is probably the easiest choice.
If you cross over around the baffle step frequency you can probably get away with just bumping up the gain on the woofer amp, however you will be losing efficiency below the baffle step frequency. You probably should be allowing for a minimum of 3db loss (which would fit with your 105db if you max out at 108db)
The baffle geometry will affect your crossover so it is worth getting familiar with it's role in the whole design process.
Placement of the speakers will have an effect as well, if the speakers will be quite a long way from the wall you may need more than 3db of compensation.
Tony.
Suggest upto 1.5dB more (now 4.5dB), but not more than or it will be easy to overcook the bass eg 6dB, full compensation.
As mentioned above, it depends on the room.
I find this program very accurate: Loudspeaker Design Software
Thanks Tony, I'll download it and have a play. i did do some reading on baffle step after Face raised it, so i understand somewhat more about it now, but I'd still find it hard to quantify with any confidence without some help from a simulation programme so those could be most useful.
The speakers will be reasonably close to a wall, but its messy and less than ideal as they'll be partially in or just in front of some 12" deep 3' wide alcoves either side of the chimney breast. This may help subs and infrasonics, but in the case of these main speakers I don't want to go for any type of design thats too sensitive to placement, as far as thats reasonably possible anyway.
EDIT: one thing I have considered is panelling directly across the alcoves to the chimney breast to form a continuous flush wall/baffle across that end of the room, with the alcoves serving to house the enclosure behind, there would be far less step down for the bass driver and quite a lot of volume for the cabinet that way, and it would simplify the number of internal corners and reflections, too. but maybe thats excessive...
Cheers
kev
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Thanks also Greebster and face, yeah it seems like it could be a range of values depending on circumstances.. So I'll also have a look at the Diffraction and Boundary Simulator stuff, looks interesting from the screen shots.
I think ultimately i'll have to build some trial enclosures and get some sort of microphone for actual testing before I leap in with making the real cabinet. But if I can get it roughly right to begin with it'll help avoid fundamentally awkward mistakes with the choice of drivers.
Cheers
kev
I think ultimately i'll have to build some trial enclosures and get some sort of microphone for actual testing before I leap in with making the real cabinet. But if I can get it roughly right to begin with it'll help avoid fundamentally awkward mistakes with the choice of drivers.
Cheers
kev
A potentially daft question.. The SPL/sensitivity charts and specs for drivers don't always say if they were taken in a baffle or not (sometimes they do and have been), which may be one reason why WinISD often has a slightly different view of what the sensitivity is.
Should I assume that WinISD's sensitivity calculations are always for just the driver and that baffle gain would be on top?
Thanks
Kev
Should I assume that WinISD's sensitivity calculations are always for just the driver and that baffle gain would be on top?
Thanks
Kev
I have looked into baffle step a bit more now; its perhaps not as scary as i thought, though I think i'd need measuring equipment to have confidence in purposely using it rather than avoiding it.
There are circuits that would help compensate, but would I be right in thinking that arranging the baffle size to step at about the mid/bass crossover frequency would let me compensate well enough simply through altering the relative driver/amp power?
Cheers
kev
There are circuits that would help compensate, but would I be right in thinking that arranging the baffle size to step at about the mid/bass crossover frequency would let me compensate well enough simply through altering the relative driver/amp power?
Cheers
kev
Have it and is a very good suggestion.
Still relying on my rules of thumb, they hold up quite well and when they don't I'll crank up BD/BS
The width changes the frequency where BSL kicks in. Wider, lower the frequency, narrower higher. If made sufficiently wide we don't have loss aka an infinite baffle. Floor loading also doesn't have the low end loss caused by a narrower than optimal baffle that plagues tall thin towers. Changing level will raise or lower the entire spectrum of said driver when what we require is more akin to a shallow low pass filter, which sacrifices effeciency at the top end. Adding additional drivers as in an mtmMM where the MM sums with the mm to compensate without loss of effeciency. This can be 2/3 or 4 additional drivers depending on placement eg 3dB, 4.5dB and 6dB compensation. Floor loading with only two drivers gain 6dB, in this case EQ is your friend.
Ah, thanks indeed. Yes i see what you mean about the shallow pass filter rather than raising the whole driver; guess the 'step' is too much of a gentle slope to deal with using driver power and a 4th order crossover point.. Possibly it would be easier to arrange for the baffle step to occur within a single driver's range and tweak just that driver's response curve. EDIT: although maybe its stoo shallow to fully do that..
I'd read about using extra drivers to fill in for losses via baffle step, but i suspect that may be getting a bit complex for my first real build. Although.. I would probably trust myself to try the floor loading with a sub.
cheers
kev
I'd read about using extra drivers to fill in for losses via baffle step, but i suspect that may be getting a bit complex for my first real build. Although.. I would probably trust myself to try the floor loading with a sub.
cheers
kev
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that will usually be a 2.5way
(mostly a 2way with two identical woofers)
in a 3way its good practice to use a woofer with higher sensitivity that the mid
but BSC can be a very delicate balance act
its easy enough to attenuate a midrange
if you can live with that
but you really do not want to attenuate a woofer, in the common sense
but might be done by using very big inductor
though not very practical, and expencive
btw, box tuning could in some cases have some influence
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