:: The Problem With Hi Fidelity ::

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#81
Pan said:
LineArray,

while agree with much of what you say there are some things that could be discussed.

I should add that I'm mostly a dipole guy as well since a number of years back however boxed speaker can perform extremly good if they are well designed and (most important) the room is taken care of. Now that's the problem I'd say.. most people don't have a dedicated room and therefore there is only so much that can be done to the room. Dipoles normally perform good with much less effort put into the room acoustics.

In a well designed box speaker there are no disturbing cavity resonances or pipe resonances. The owerblown bass is due to poor match between speaker and room. Take a bassreflex speaker outside and suddenly what was boomy in the livingroom is hard hitting high quality bass.


/Peter
Click to expand...


Peter,

i am with you. Dipoles - or lets say systems with high directivity -
perform better in suboptimal listening rooms.

Poor bass performance is mostly due to speaker - room
interaction.

But the suboptimal listening room is the de facto standard.
Only few people can afford a dedicated listening room, mostly
the room has to serve mainly as a living room.

I have no dedicated listening room too.
 
#82
I like the OB sound as well, but I really think that it is most approriate in the midrange.
Well designed vented or sealed bass iis perfectly suited to low end duty.
The problem with dipole bass is that it forces a whole heap of things. Just look at the Orion, beautifully implemented, but look at the electronics required.
The dipole bass virtually has to use high excursion sub drivers and plenty of grunt. This limits the top end to around 100Hz, so you then have to use larger diameter mid drivers so you can eq them down to meet the subs. This in turn leads to having to pull the tweeter down and use steep slopes, to adequately meet the mids. It can be done, but only with heaps of electronics or purely digital x-o.

An alternate way to approach the situation is to forego the dipole bass, just a normal old style bass driver vented or sealed. Even a pair of 4.5" or 5" can easily get to around 200Hz when used in a U-frame open back design, so a passive x-o now becomes a reality if you choose the right drivers. (IMO the simpler the x-o the better) 😉
This in turn means that you don't have to push the tweeter down to meet the larger mid driver.

Have a look at a couple of implementation of these ideas, then think if they could work for you

http://members.optusnet.com.au/~gradds55/ARGOS/blackwood.html
http://undefinition.googlepages.com/diy-aethers

The results will please your ears ! 😀
 
#85
Andy Graddon said:
I like the OB sound as well, but I really think that it is most approriate in the midrange.
Well designed vented or sealed bass iis perfectly suited to low end duty.
The problem with dipole bass is that it forces a whole heap of things. Just look at the Orion, beautifully implemented, but look at the electronics required.
The dipole bass virtually has to use high excursion sub drivers and plenty of grunt. This limits the top end to around 100Hz, so you then have to use larger diameter mid drivers so you can eq them down to meet the subs. This in turn leads to having to pull the tweeter down and use steep slopes, to adequately meet the mids. It can be done, but only with heaps of electronics or purely digital x-o.

An alternate way to approach the situation is to forego the dipole bass, just a normal old style bass driver vented or sealed. Even a pair of 4.5" or 5" can easily get to around 200Hz when used in a U-frame open back design, so a passive x-o now becomes a reality if you choose the right drivers. (IMO the simpler the x-o the better) 😉
This in turn means that you don't have to push the tweeter down to meet the larger mid driver.

Have a look at a couple of implementation of these ideas, then think if they could work for you

http://members.optusnet.com.au/~gradds55/ARGOS/blackwood.html
http://undefinition.googlepages.com/diy-aethers

The results will please your ears ! 😀
Click to expand...

I kind of used to agree with this (substitute bass horn or karlson for box) but after building several open box systems I find that dipole configurations benefits best in the bass. You really don't need to eq it either if you don't mind building a big system with the right bass drivers and using a sub that will mate well. Also electronic crossovers have many advantages over passive ones - mainly in low IM distortion, better dynamics, more control and more transparent sound. A 'big' tweeter can very be a controlled directivity (the main reason open baffles sound good in a room!) compression driver in a horn. I have some that can be crossed over as low as 300 cycles. That makes a fairly simple two way with a sub.
 
#86
I don't want to get this thread out of topic as it seems OB users feel very strongly about their system2 :smash:. But that link above about Aethers system may be the 'perfect compromise' of OB design with good bass. I shall try it :angel:

http://undefinition.googlepages.com/diy-aethers

... now that alot has been spoken about speakers, what about the source? Is moving from 16/44kHz to 24/96 or even 24/192kHz is a 'revelation' ? Should I start to invest in 24/96 DAC and material ?
 
#87
gainphile said:
But that link above about Aethers system may be the 'perfect compromise' of OB design with good bass. I shall try it :angel:
Click to expand...

That's basically what I was aiming at with the design. Smaller mids have always sounded "tighter" to me, but the normal way of doing OB or dipole just seemed too complicated, required mids that were too big, or may not have been full range enough to meet my tastes.

I think you do need the MTM to get the power response from that size mid driver, and I do recommend that you choose your drivers so you can keep the x-o simple.

The lower x-o point is naturally set in the 180-240 range by the U-frame 4.5" or 5" mtm, so your bass has to do 2 x that frequency without problems, so sub drivers are mostly out of the picture.

As you are an Aussie, I would recommend trying the old Jaycar 10" hi-power poly. They are on run-out special pricing at the moment, and they do nice smooth clean bass for this purpose.

Have fun !! :smash:

As for the hi-def stuff.. nothing seems to have taken off big time yet, so I'm just biding my time on that.
Maybe something worth listening too may find its way onto SACD eventually ! :devily:
 
#88
Andy Graddon said:
I think you do need the MTM to get the power response from that size mid driver, and I do recommend that you choose your drivers so you can keep the x-o simple.
Click to expand...


Andy, did you try running only one mid?

I started out with MTM dipoles but then I tried a single mid and prefered that. Should confess that I did no rigorous testing with the exact same drivers and not even in the same room.. but my collected experience with several dynamic dipoles tells me that.

Have listened to three of my own designs + SL's Dvorak, Vivaldi and Orion.

However even though I prefer dipole operation down below 100Hz I did one design similar to yours that performed very well. It was a Dynaudio Esotec tweeter with Dynaudio Esotec 5"
on top of a big closed box containing 3x 10" (SS8565). The speaker played in a very big room and had a very lifelike quality.


/Peter
 
#89
Magnetar said:


Also electronic crossovers have many advantages over passive ones - mainly in low IM distortion, better dynamics, more control and more transparent sound.
Click to expand...


Do you mind if I ask how you came to that conclusion?

Normally driving the voice coil from a higher impedance in part of the range lowers distortion and makes for less thermal compression. The heating of the voice coil obviously becomes the same for a given output as when driven with a low impedance but the net effect is less compression.

The distortion should be lower because the high impedance drive linearizes (is that a word?) the modulated current in the voice coil that results from non linear inductance.


/Peter
 
#90
Pan said:

Andy, did you try running only one mid?

/Peter
Click to expand...

I suspect it depends on the mid you use. The Vifa M11WG is purely a mid and really would start to struggle in the lower range at high volume levels giving a lack of "body" in the 200-400 region. There are, however, many 5" drivers that could possibly cope very well as a single driver.

I do have one design using a single 4" Peerless with a 6.5" bass, but it is really only a bit bigger than book shelf size.
http://members.optusnet.com.au/~gradds55/ARGOS/Sauron.html

You also have to consider that I prefer low order series x-o and the use of the MTM halves the amount of low end stuff each mid has to try to do. With steeper cross-overs, again, maybe one mid might be enough....... but that is against my design philosophy 😀
 
#91
Hey Andy, nice stuff, thanks for the links!

Good old Lukaz "Lampiztor" is certainly a fan of the open mid and tweeter supported by box bass.
Check out his many projects.

Not a bad solution for those of us who can't build Magnatar size rigs.

I did try the approach, but could never get the bass right. I do like the idea, tho.
 
#92
SamL
( Hi Zero One,

Interesting!! Which 4 in driver and how many are you using. I like small drive for it excellent off axis response. Was told 4in is no good for OB )

Nothing fancy they start out life as these:

http://www.altronics.com.au/index.asp?area=item&id=C0626

and these

http://www.altronics.com.au/index.asp?area=item&id=C0635

Cheap as chips but once modded the sound is fabulous

Here is a pic of one of my modded C0626 drivers from the rear. It attached to a sub baffle which actually fits inside a much larger baffle without touching it, so basically a magnet mounted driver.
 

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#96
Multi Amping

Pan said:



Do you mind if I ask how you came to that conclusion?

Normally driving the voice coil from a higher impedance in part of the range lowers distortion and makes for less thermal compression. The heating of the voice coil obviously becomes the same for a given output as when driven with a low impedance but the net effect is less compression.

The distortion should be lower because the high impedance drive linearizes (is that a word?) the modulated current in the voice coil that results from non linear inductance.


/Peter
Click to expand...

IM Distortion

Biamping, triamping,quadamping, ect. = Higher order slopes can be used with less insertion loss. Direct drive with low source impedance amplifiers in dedicated passbands raises the dynamics by the amplifiers not having to produce the full range signal - With multiamping he amplifiers are not seeing the complexity of some crossovers, and may use sharper slopes lowering out of band distortion. The crossovers are more accurate because they aren't working in a reactive load, but a fixed load. Dynamic headroom goes up, IM distortion goes down and the sound becomes more transparent. If frequency contouring is needed it can be done more accurately at a lower cost with more precision. Relieving the midrange and treble amps of having to drive the lower frequencies lowers the distortion and raised the headroom. Amplifiers can be used that work best into the load presented (ie tube amps)

A well implemented multi-amp system can be a 'revelation' on it's own. Most studio monitors and pro speakers either uses multi-amping or built in multi-amps and electronic crossovers. The pro's do this for several reasons but what it comes down to is better performance. The sound quality advantages can be extraordinary in a home system. Things like 'special wire', 'expensive passive components', and 'special amplifiers' diminish and are replaced by transparent, dynamic, satisfying music reproduction.
 
#99
Andy Graddon said:
That's basically what I was aiming at with the design. Smaller mids have always sounded "tighter" to me, but the normal way of doing OB or dipole just seemed too complicated, required mids that were too big, or may not have been full range enough to meet my tastes.
Click to expand...

My current OB uses a set of Dick smith 5.5" and they sound so alive I'm afraid to change anything -- fast and transparent albeit $13 from ebay. Now.. I have a pair of 6.5" do you think these can match the 5.5" given everything else equal ?

Or would I better invest another pair of 5" mids ?
 
#100
Re: Multi Amping

Magnetar said:
Relieving the midrange and treble amps of having to drive the lower frequencies lowers the distortion and raised the headroom. Amplifiers can be used that work best into the load presented (ie tube amps)
Click to expand...


Gotta be easier on the power supplies, too - right?

But all amps sound the same, so why worry? 😉
(Sorry, that's another thread)
 
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