Nearfield Stargate

I found the post here recently about the headphones vs speakers interesting -

My current speaker project/idea is to build a near/mid field speaker system to compete with Signet Electret headphones in detail and smoothness yet still have the 'live' illusion with all the power, dynamics, and 'feel' of a large fullrange horn system. Most important here is using very 'fast' and linear drivers and configuring them for the LEAST 'negative' room interaction -

The goal is to allow 3 people to be able to share this illusion (wide sweet spot) from under 8' away. This rules horns out for use below 600 cycles (too wide of driver spacing for close listening)- so I am steering towards a near full range cardioid with 100 db+ sensitivity. Problem is getting it to appear as a point source at close distances and still be 'full range' and with low dynamic compression.

Has anyone here had success at this?

How did you achieve it?

Binauraul cardioid??? Can't do it - have a projection screen between the speakers.
 
mission (almost) impossible

(sorry for my english)
Hi Magnetar,
IMHO you can do a choice: power vs accuracy. If you take the second
think at a 6 feet triangle with one pair of minimoitors and a very massive absorbant treatment of early reflections ( ideally a LEDE).
Now you can start to experimentate all the x-overs and drive units
you want. When the speakers "disappear" and the timbre is very close to your ref headphones you are OK. ;)
IMHO very high levels are not indispensable with this setup.
A lot of passion and time is necessary because "standard-sound" is very far from this IMHO.
regards
 
Hi Mag

I suggest you look at co-axial speakers. Maybe a pair of Tannoy 15" drivers (Red, Gold or HPD) with suitable subwoofers in an tower with the subwoofer drivers flanking the Tannoy driver. It'll be big, but might suit your needs. The are other drivers that might also work (one suggestion might be the B&C co-axials). Just an idea.

Enjoy,
Deon
 

Bill F.

Member
2001-11-15 5:25 pm
SW MI
If you're not afraid of digital...

I'll second the coaxial suggestion.

Were I doing it, I might divide off the sub-bass (where the wavelengths are long enough that everything's nearfield) and send it to a nice big sealed sub or array of subs that are out of the way. That will let you use higher-efficiency midbass drivers and have less massive nearfield units. Nearfields would be delayed to time align them.

For the midbass, I might try a 2nd-order gradient (twice the directivity of a cardioid for least poss. room interaction). They're complicated to set up in the analog domain, but relatively simple to do digitally.

A second-order gradient is simply two dipoles separated by x meters. The rear dipole is wired out of phase with the front and delayed x/1100 seconds. Since a 2OG rolls off at 12dB/octave, they don't go very low and EQ is required.

I plan to experiment with making one with a DEQ2496 and a soon-to-arrive Panasonic XR25.
 
Magnetar said:
I found the post here recently about the headphones vs speakers interesting -

My current speaker project/idea is to build a near/mid field speaker system to compete with Signet Electret headphones in detail and smoothness yet still have the 'live' illusion with all the power, dynamics, and 'feel' of a large fullrange horn system. Most important here is using very 'fast' and linear drivers and configuring them for the LEAST 'negative' room interaction -

The goal is to allow 3 people to be able to share this illusion (wide sweet spot) from under 8' away. This rules horns out for use below 600 cycles (too wide of driver spacing for close listening)- so I am steering towards a near full range cardioid with 100 db+ sensitivity. Problem is getting it to appear as a point source at close distances and still be 'full range' and with low dynamic compression.

Has anyone here had success at this?

How did you achieve it?

Binauraul cardioid??? Can't do it - have a projection screen between the speakers.

Please email [email protected] he has the design you're looking for....
 
I think 3 people may be a bit ambitious, that means you want a sweet spot as big as a couch, with speakers less than 8' away? I listen from 7' away and no speaker I've tried (even fullrange) gives a sweet spot that size. The image always pulls to one side or the other for the 2 outside listeners on the couch. In general the closer you get the smaller the sweetspot.
 
morbo said:
I think 3 people may be a bit ambitious, that means you want a sweet spot as big as a couch, with speakers less than 8' away? I listen from 7' away and no speaker I've tried (even fullrange) gives a sweet spot that size. The image always pulls to one side or the other for the 2 outside listeners on the couch. In general the closer you get the smaller the sweetspot.

I've heard several ESLs that did not do that from around 10 feet away
 
morbo said:
I think 3 people may be a bit ambitious, that means you want a sweet spot as big as a couch, with speakers less than 8' away? I listen from 7' away and no speaker I've tried (even fullrange) gives a sweet spot that size. The image always pulls to one side or the other for the 2 outside listeners on the couch. In general the closer you get the smaller the sweetspot.

I forgot to mention I use Circle Surround with a center and two rear channels - (3 extra channels) - The center channel. when on. stabilizes the center pretty well- if we sit close enough :)

What I have done is a 'compacted' my current speakers into a smaller package (the dual 15" midbass drivers are now in one cabinet and still get to 60 cycles, one pair of PP dipole mids instead of 2) - It's no longer an MTM and driver spacing is very tight, it's getting close to what I am trying to achieve, next step is to reposition the center channel - maybe above me pointing down I had to retune the bass for different speaker position - this is fun. The main speakers are now 7' away (they were 11.5') - the detail went up a notch and the soundstage got deeper- so it seems - it's also measuring a bit better from 200 cycles up.
 
Magnetar said:


I forgot to mention I use Circle Surround with a center and two rear channels - (3 extra channels) - The center channel. when on. stabilizes the center pretty well- if we sit close enough :)

What I have done is a 'compacted' my current speakers into a smaller package (the dual 15" midbass drivers are now in one cabinet and still get to 60 cycles, one pair of PP dipole mids instead of 2) - It's no longer an MTM and driver spacing is very tight, it's getting close to what I am trying to achieve, next step is to reposition the center channel - maybe above me pointing down I had to retune the bass for different speaker position - this is fun. The main speakers are now 7' away (they were 11.5') - the detail went up a notch and the soundstage got deeper- so it seems - it's also measuring a bit better from 200 cycles up.


Why not use 2 15" lambda's as midbass
2 PHL midranges in Dipole
And a pro audio ribbon?

the lambda's ported could EASILY be flat to 30 hz... also they have unmatched midbass SQ
 
Audiophilenoob said:



Why not use 2 15" lambda's as midbass
2 PHL midranges in Dipole
And a pro audio ribbon?

the lambda's ported could EASILY be flat to 30 hz... also they have unmatched midbass SQ


EACH front channel I use one Electro Voice EVM15B front firing, one Electro Voice EVM15L rear firing (with 0-180 degree phase adjustment), Two JBL 2123J's as mids (pp dipole) , and the big Heils for treble. ( I find the G1 ribbons to be too fragile) Almost what you suggest except I like these drivers better.

AFA midbass - the EV's and the Altec 421-8LF (as well as custom field coils) sorta whomp the **** out of the PHL 5230's I had. - not sure if the lambda's can compete - Below 60 cycles I use three horn loaded JBL 2242H 18's (These are NUTS - ) - it's quad-amped - but I need to use two stereo amps for the midbass due to the phase adjustments.
 
ahhh well if you're using a surround method with a center speaker, then of course it is a different story. This could be a very nice system you are putting IMO, would be very interesting to hear to be sure. I personally like some things about nearfield listening a great deal, especially when using fullrange drivers to do the 100hz-up duty. IMHO nearfield is one place where a fullrange pointsource REALLY shines.
 
Magnetar said:



EACH front channel I use one Electro Voice EVM15B front firing, one Electro Voice EVM15L rear firing (with 0-180 degree phase adjustment), Two JBL 2123J's as mids (pp dipole) , and the big Heils for treble. ( I find the G1 ribbons to be too fragile) Almost what you suggest except I like these drivers better.

AFA midbass - the EV's and the Altec 421-8LF (as well as custom field coils) sorta whomp the **** out of the PHL 5230's I had. - not sure if the lambda's can compete - Below 60 cycles I use three horn loaded JBL 2242H 18's (These are NUTS - ) - it's quad-amped - but I need to use two stereo amps for the midbass due to the phase adjustments.


the lambda is easily the greatest speaker ever made as far as wide bandwith high SPL SQ is concerned...

the lambdas are 97db efficent and have a tested 15 mm one-way excursion... HP them at 30 hz... they would kill anything out there... and in SQ they are better than anything also... their max SPL would be unbelivable if you HP that at 60 hz like your setup

but if you like these... go with that...
 
morbo said:
ahhh well if you're using a surround method with a center speaker, then of course it is a different story. This could be a very nice system you are putting IMO, would be very interesting to hear to be sure. I personally like some things about nearfield listening a great deal, especially when using fullrange drivers to do the 100hz-up duty. IMHO nearfield is one place where a fullrange pointsource REALLY shines.

When I get tired of this - (I will) - I'm thinking of maybe some 12 or 15" Tannoy, JBL, Altec , URIE, PAS, ect.. coaxial 2-way drivers would be fun to listen to. - I have some EV SP10's and they sound pretty sweet with a helper tweeter and mid power (8 watt 300B) SET amps.
 
morbo said:
I would think coaxes or coincidents would also work really well in this kind of setup, though IME they still don't image as well as a fullrange. Probably better dynamics though, especially if they are 10" or greater!

I now have a pair of Tannoy 6.5" Dual Concentric drivers out of 600 nearfield monitors. What I've done so far is put them on a 22" wide baffle with a 14 liter sealed back chamber. They are going down to 80 cycles solid - (wow are these little drivers linear - EXCELLENT power response!)

Now I'm going to biamp the Tannoy drivers and high pass them somewhere between 120-200 cycles with my Karlson Klam's loaded with EVM 15B's for midbass from 60 cycles up. Triamping like this *should* get me the SPL capability I'm looking for - just hoping the 6.5" 'mid' portion will not be dynamically compressed. The tulip horn tweeter in these really are pretty good - and extended well past 15k- the stock 2nd order network is a bit hot - triamping should be sweet

f5_1_b.JPG
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As I suspected the 6.5" Tannoy has problems

with full scale symphonic (live levels) even bi-amped and crossed over at 250 Hz.

I have a solution that is VERY promising - I loaded the Tannoys in my big 180 Hz round tractrix horns and small back chamber. Added a small bit of passive eq on the concentric tulip tweeters, (bi-amping the tannoys) and am now listening to what in my humble opinion is pure nearfield (about 7') musical bliss - the concentric horn is doing 150 to 20k with very little interchannel crosstalk - Low interaural crosstalk without a center wall between channels is a goal I have been trying to achieve for years - imaging is spooky - around 98 db/watt/meter Hz from 180 cycles up - a bit more sensitivity below that.

Keele talks about Crosstalk problems you all experiance

Part Two