Well these are only supposed to be the experimentation stage of my open baffle adventure! I didn't want to send huge sums on drivers before I knew I could make it work for me.
Plus I really want to go down the passively EQ'd route if I can.
I have also read the huge battle of opinions over the high Qts Vs. low Qts, and oh my!
I'm in no hurry so I'll have a go with these cheap as you like drivers and then move on to something more expensive wuth a lower Qts and higher SQ later on....... I'll be able to see for myself which is better.
The experiences of others are all well and good...... but you really need to try things for yourself!
Plus I really want to go down the passively EQ'd route if I can.
I have also read the huge battle of opinions over the high Qts Vs. low Qts, and oh my!
I'm in no hurry so I'll have a go with these cheap as you like drivers and then move on to something more expensive wuth a lower Qts and higher SQ later on....... I'll be able to see for myself which is better.
The experiences of others are all well and good...... but you really need to try things for yourself!
I don't want to steal the thread, but can you elaborate a little. What path length are you using, what drivers, what SPL are you able to achieve, at what SQ results????
Thanks!
Ribbon Project
The woofers were a paltry £27.42 each inc VAT.
There are available from West London Electrical .
Their shipping cost are also pretty reasonable. I think they charged me about £10 for postage on the whole shipment.
There are available from West London Electrical .
Their shipping cost are also pretty reasonable. I think they charged me about £10 for postage on the whole shipment.
Mutley666 said:
Hi,
http://www.skytronic.co.uk/about/storefinder.php
use this link to find your local distributor.
/sreten.Mutley666 said:
Hi,
I'll just note electrostatics and mageneplanars routinely use bass Q's
of around 3 to extend bass response, this of course defines a sharp
cut-off (18dB/octave) below the bass resonance.
Also the reason for Quad ESL surprisingly (to some) poor bass power handling.
One things for certain, high Q open baffle bass alignments have lower
bass power handling than you'd expect, conversely pretty good efficiency.
But in the end the amount of low bass depends on cone area and excursion.
Also note that low DCR (expensive) inductors are not necessary,
assuming a DCR of around 1 ohm the Q will go up to ~ 1.
Mutley666 said:
Suggest you investigate these drivers :
http://www.zaphaudio.com/audio-speaker12.html
Allthough not stated in the article, Zaph usually has details
of a crossover without beffle step, which could be useful.
Mailing him could be an idea.
edit : or this combo of drivers :
http://www.zaphaudio.com/audio-speaker17.html
Which definetely has a reduced baffle step crossover available.
/sreten.
Re: Re: Re: Time To Try Open Baffle
Hi,
Unsurprisingly the polar response will also be assymetric.
At a given polar angle a (real) dipoles front to back cancellation
descreases with increasing frequency or increases as you go
down in frequency (6dB/octave in the baffle loss region).
The position of thse curves will be different on the various axis.
e.g. 30 degrees left, right,up, down.
The major differences will be in the transition region, as baffle
loss begins to take effect and the baffle size interacts strongly
with the wavelength of the sound.
At high frequencies the polar response of all axis will be identical.
Hope this answers your question.
/sreten.
Raka said:
Hi,
Unsurprisingly the polar response will also be assymetric.
At a given polar angle a (real) dipoles front to back cancellation
descreases with increasing frequency or increases as you go
down in frequency (6dB/octave in the baffle loss region).
The position of thse curves will be different on the various axis.
e.g. 30 degrees left, right,up, down.
The major differences will be in the transition region, as baffle
loss begins to take effect and the baffle size interacts strongly
with the wavelength of the sound.
At high frequencies the polar response of all axis will be identical.
Hope this answers your question.
/sreten.
As I see it, the major advantage of the dipoles are the radiation pattern control, and a homogenous polar diagram as a target (including of course the xover points). If you use asimetrical arrangements, I can't see how you would get it unless you put all the drivers in the same vertical line.
Any way, it's interesting, maybe it can be done. I don't know.
The diffraction, understood as the effect that introduces ripple in the frecuency response, hasn't been a problem with my 3 way dipoles.
Any way, it's interesting, maybe it can be done. I don't know.
The diffraction, understood as the effect that introduces ripple in the frecuency response, hasn't been a problem with my 3 way dipoles.
Hi guys
One thing about open-baffle bass that I have not seen mentioned in a long time is that it is better not to have OB bass below the lowest room mode of your listening room. Thorsten was the first one (that I read about) that suggested using OB bass down to the lowest room mode and then use sealed, LT bass below that. Aperiodic (LT-ed) or IB bass could also work. Apparently it loads the room better. Any comments on this?
Deon
One thing about open-baffle bass that I have not seen mentioned in a long time is that it is better not to have OB bass below the lowest room mode of your listening room. Thorsten was the first one (that I read about) that suggested using OB bass down to the lowest room mode and then use sealed, LT bass below that. Aperiodic (LT-ed) or IB bass could also work. Apparently it loads the room better. Any comments on this?
Deon
Raka said:
Two effects should be separated:
The figure 8-erasement in the dipole plane is fully independent from the baffle shape or the position of the driver on that baffle - as long as every given point on the baffle edge has equal distance to the front- and back-side of the driver.
Superimposed on this is edge diffraction - a different game. With unsymmetrical position of the driver on the baffle it will lead to an unsymmetric polar response. That can very well be a desired design target.
Raka said:
Hi,
You would put all the drivers vertically.
In practise at the bass mid crossover point its hard to not effectively
mount the drivers vertically whatever the midrange position offset.
This leaves the midrange and tweeter, and both should be
carefully spaced from the edges to minimise diffraction ripples.
You can do this and still maintain vertical alignment.
If needs be you can make the baffles mirror images.
Minimising the ripples in the on axis response also minimises the
ripples in the off axis response, which is far more important than
assymetries in the polar responses.
All that happens in terms of polar responses in that the baffle
appears to slightly larger on one hand of the responses.
/sreten.
I'm sorry but I can not see how to maintain an 8 pattern constant with frequency if you don't put the drivers in the very same vertical line.
I attach a very dirty image to explain myself. It's the top view, I mean, your head is on the ceiling.
PS : Yes, of course the ripples are important off axis, but in my short experience those get smoothed off axis.
I attach a very dirty image to explain myself. It's the top view, I mean, your head is on the ceiling.
PS : Yes, of course the ripples are important off axis, but in my short experience those get smoothed off axis.
Attachments
Hi,
if the offset of the mid driver is very small compared to the wavelength
the mid and bass crossover, then in your top down view, acoustically
the drivers will be very close together.
The typical placement of the mid unit is 0.6 of baffle width, so
we are talking about an offset of 0.1 baffle width, it's not a lot.
/sreten.
if the offset of the mid driver is very small compared to the wavelength
the mid and bass crossover, then in your top down view, acoustically
the drivers will be very close together.
The typical placement of the mid unit is 0.6 of baffle width, so
we are talking about an offset of 0.1 baffle width, it's not a lot.
/sreten.I believe that the recommendation pointed out by Deon is that you want to avoid going dipole below the "on axis room mode". In my room that just happens to be the long dimension and it is the one that has concrete boundaries. Dipole (figure 8) or U-baffle (cardoid) are very problematic at the on axis mode and it has nothing to do with driver alignment. The effects of this mode are much more pronounced, I believe, because of the greatly reduced energy along the other axes. If my listening position was oriented another way, that lowest mode wouldn't matter, because it wouldn't be stimulated.
Raka said:
Raka,
of cause every driver has its own figure 8 pattern as you already pictured. Along the hearing axis the offset of the drivers has some influence, yes - in the same way as a closed box would have.
But for the erasement in the dipole plane it really does not matter, how far the distance between the two drivers is.
So the detrimental effect of two drivers not aligned vertically on the baffle is zero in the dipole plane and maximum at 90° from there.
May be this doesn´t explain much, but it´s difficult for me to find the appropriate words in english.
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