off-topic posts from http://www.diyaudio.com/forums/multi-way/212194-whats-best-pair-speakers-youve-ever-heard-35.html 
I am running a pair of these Behringer Truth B2031A active monitors.
Now modified, these are one of the best loudspeakers I have heard.
As standard they were sending me out of the room, now they are pin sharp in clarity/detail, centre, width and depth imaging.
These loudspeakers are both clinically detailed and perfectly musical, and go pretty loud.
These are seriously good fun, and at their price point quite unbeatable.
Dan.
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I am running a pair of these Behringer Truth B2031A active monitors.
Now modified, these are one of the best loudspeakers I have heard.
As standard they were sending me out of the room, now they are pin sharp in clarity/detail, centre, width and depth imaging.
These loudspeakers are both clinically detailed and perfectly musical, and go pretty loud.
These are seriously good fun, and at their price point quite unbeatable.
Dan.
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Yes, do tell us. as standard, according to some accounts in the other thread these beat Linkwitz Orions.
Polishing A Turd...
My Behringers are really just conventional 2 way cabinets with Behringer's crossover/amplifier module tacked on the back.
The tweeter is mounted to a shaped/short horn/waveguide front plastic panel that screws to the front of the cabinets.
The tweeter claims titanium but doesn't look anything extra special.
The woofer looks quite decent and incorporates a very substantial magnet assy.
The electronics is balanced input/level/crossover stage (all 4580 opamps) feeding LM3886 amplifiers.
View attachment Behringer - B2031p - Schematic - Crossover.pdf
View attachment Behringer - B2031p - Schematic - Output.pdf
At this point I have very deliberately avoided making any changes to the amplifier module whatsoever, for now.
My mods so far are....
Changing out the speaker cable assy to enamelled 1mm wire, using new Molex and spade connectors.
Removing all original damping material.
Using 'acoustic pinboard' to line the rear panel (two pieces).
Cutting two panels of the pinboard and curling them around to form tubes that fit precisely into the front panel driver cutouts.
These 'tubes' finish around 2cm short of the rear panel.
The tube behind the (closed back) tweeter is intended as 'freestanding' acoustic damping material.
The 'tube' behind the woofer is intended as the same, and also forms a 'port' of sorts.
Trying the spoken/ummm/oooooh/ahhhh testing sounds into the original cabinets excited all sorts of booming and emphasis.
Doing the same into the relined versions, I could not excite any resonances...just well behaved, with really good damping.
The result now is a pair of speakers that have clarity and dynamics to die for.
Anywhere around the house and the sound is great, in the sofa sweetspot the imaging is quite spectacular....according to the recording, sounds come from precisely placed locations across the room, and from miles through the wall.....from behind the listener also.
Because of this hologram 3D positioning, every instrument/sound source is perfectly and easily discernable.
This simple set of mods has quite transformed these speakers.
Dan.
Hmmm, the Orions are a completely different beast are they not ???.
My Behringers are really just conventional 2 way cabinets with Behringer's crossover/amplifier module tacked on the back.
The tweeter is mounted to a shaped/short horn/waveguide front plastic panel that screws to the front of the cabinets.
The tweeter claims titanium but doesn't look anything extra special.
The woofer looks quite decent and incorporates a very substantial magnet assy.
The electronics is balanced input/level/crossover stage (all 4580 opamps) feeding LM3886 amplifiers.
View attachment Behringer - B2031p - Schematic - Crossover.pdf
View attachment Behringer - B2031p - Schematic - Output.pdf
At this point I have very deliberately avoided making any changes to the amplifier module whatsoever, for now.
My mods so far are....
Changing out the speaker cable assy to enamelled 1mm wire, using new Molex and spade connectors.
Removing all original damping material.
Using 'acoustic pinboard' to line the rear panel (two pieces).
Cutting two panels of the pinboard and curling them around to form tubes that fit precisely into the front panel driver cutouts.
These 'tubes' finish around 2cm short of the rear panel.
The tube behind the (closed back) tweeter is intended as 'freestanding' acoustic damping material.
The 'tube' behind the woofer is intended as the same, and also forms a 'port' of sorts.
Trying the spoken/ummm/oooooh/ahhhh testing sounds into the original cabinets excited all sorts of booming and emphasis.
Doing the same into the relined versions, I could not excite any resonances...just well behaved, with really good damping.
The result now is a pair of speakers that have clarity and dynamics to die for.
Anywhere around the house and the sound is great, in the sofa sweetspot the imaging is quite spectacular....according to the recording, sounds come from precisely placed locations across the room, and from miles through the wall.....from behind the listener also.
Because of this hologram 3D positioning, every instrument/sound source is perfectly and easily discernable.
This simple set of mods has quite transformed these speakers.
Dan.
Thanks for sharing the infos Dan,
Seems to be this kind of product :
Acoustic Pinboard - Speciality Panels - Building Products & Surface Materials | Gunnersens
Ps : look at the monitors on the picture
Seems to be this kind of product :
Acoustic Pinboard - Speciality Panels - Building Products & Surface Materials | Gunnersens
Ps : look at the monitors on the picture
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Yes, that's the kind of stuff....looks like and feels like very dense felt sheet.Thanks for sharing the infos Dan,
Seems to be this kind of product :
Acoustic Pinboard - Speciality Panels - Building Products & Surface Materials | Gunnersens
Ps : look at the monitors on the picture
I am running balanced feed from Behringer line amp stage, and balanced 240V feed from medical grade 240V isolation transformer.
These speakers a very revealing of absolute polarity...my solution is to wire a reversing switch directly on the 6.5 mm input plugs feeding the Behringer preamp.
I intend to fit Zobel networks across each of the drivers soon.
I also have a curved sheet of cardboard directly behind each cabinet....this will change to curved sheets of carpet in time.
I also have another pair of these speakers in factory original condition...this will give me possibility of easily comparing boxes, and easily comparing amp modules when I get to doing electronics mods.
Dan.
Do you have measurements of the speaker after your mods. I am not so sure that putting tube right tightly around the woofer is good, I think generally you want to allow free flow if air around the back of the cone and to avoid surfaces (even absorbing material) right next to the back of the cone. But measurements would prove it all to be worth it.
FIY Zaph Audio measured the passive version of those speakers :
zaph|audio
Search b2031p in the page.
zaph|audio
Search b2031p in the page.
No measurements....need to get my mic back from loan.
I am.
The woofer is effectively back loaded by a cylinder of air, bounded by the sheet damping material, that terminates 2cm short of the rear panel.
Higher frequency back radiations have an easy path out and away from the back of the cone, but an unlikely and lossy return path to the back of the cone....in a sense a lossy diode of sorts for cone back radiations.
This is what I sought, and in practice all sense of 'boxiness' is removed, and no under or over damped sounding behaviour either.
A large point of the 'tubes' experiment is for the damping material to have 'two bites at the cherry' so to speak of internal cabinet sounds, and thereby provide increased cabinet internal damping, without significant internal volume loss.
I have tried, fibreglass, poyester, sheep wool etc in the past..all three are a pain to get the volume correct, and each has a sonic signature of its own.
The acoustic pinboard approach bypasses all that nonsense.
My ears are happy
.Dan.
I do have a bunch of further cabinet and electronics improvements in mind, but for now this is an exercise in what can be done easily, quickly and cheaply to improve an economical known benchmark loudspeaker.
Sure.
When I get into tweaking the amp modules I will do all these kinds of measurements.
For now I'm going the empirical route..hunting down nasties and reduce/eliminate them one by one using cheap/free methods....and all just for fun.
The pinboard has worked a treat.
The next most urgent matter is the plastic front panel.
I have a drum of bathroom waterproofing compound, some kind of latex based stuff I think...the dried stuff on the outside of the drum is like rubber.
I will come up with a way of building out the back of the front plastic panel with a contoured thick rubbery layer conforming to and contacting the cabinet woodwork, thus completely damping the front plastic panel.
Fitting Zobels sounds easier for now.
Dan.
Hi well this adventure deserves a separate 3D
i have a pair of these speakers
By the way i have never thought to mod them
I see now from the pictures (i have never looked inside) an impressive box construction with an interesting bracing stiffening the front baffle (this is great for me .. i am obsessed by a firm front baffle)
Seriously ... why do not open a dedicated 3D ?
I have seen pairs of these speakers selling for 150 USD (2nd hand of course)
Just a decent preamp in the front and bam !
Thanks a lot anyway
Kindest regards, gino
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Ok that makes sense....Gino, speek english more proper please
.In the next few days I will take some photos, and start a thread.
Dan.
Ok that makes sense....Gino, speek english more proper please
Hello Dan,
sorry for my misuse of the language ... but English is only my fourth language
But i can assure you that i am trying to improve also with the help of friends here
Thanks you very much indeed.
As i said i have a pair of these speakers.
So i am very interested in any mod that can make them sound better.
Actually i was thinking to put another pair of woofers ... smaller and better.
Like two very good 6-7" ... they are crossed high at 2kHz
Maybe a little high for a 8"
But i will read carefully your new ... thread
Kindest regards, gino
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