I'm looking to replace my existing standmount speakers with some louder and deeper responding floorstanders. The position in the room is non-negotiable. I've been looking at various designs such as Zaph's waveguide TMM (best I've looked at so far) and one common thing I've come across is a dislike of speakers being used close to room boundaries.
However I am stuck with the speakers being in this postion so how best to utilise it? I presume the corner loading gives a boost in the lows - does it mean that baffle step correction is not required?
Alex
However I am stuck with the speakers being in this postion so how best to utilise it? I presume the corner loading gives a boost in the lows - does it mean that baffle step correction is not required?
Alex
My original inclination is towards an MTM floorstander, with 5"-7" woofers and a dome tweeter than can cross over fairly low. I do like big bottom - I'm a bass player - and also will be watching films through the system. My current speakers on stands are 8.5" wide and 39" high - I can probably go about 10" deep.
My amp is a Rotel RA-917 MkII. A 4 ohm load would make sense as the amp is happy with that and it'll give another 2dB of headroom.
I am overwhelmed by the choice available! I'd like to keep the component cost down to no more than $500.
Alex
My amp is a Rotel RA-917 MkII. A 4 ohm load would make sense as the amp is happy with that and it'll give another 2dB of headroom.
I am overwhelmed by the choice available! I'd like to keep the component cost down to no more than $500.
Alex
Speakers in corners is not a bad thing if you want more bass - try building them with no BSC at first and see if the corner loading does enough for you.
Being able to measure and then adjust accordingly will be a big help also, as you may run into some FR peaks/valleys with the corners - some sound absorbing panels may be in order, if there are no aesthetic conflicts.
Being able to measure and then adjust accordingly will be a big help also, as you may run into some FR peaks/valleys with the corners - some sound absorbing panels may be in order, if there are no aesthetic conflicts.
Hi,
quoting Zaph himself :
The secret of good bass extension is use of room gain by placing
speakers away form the room boundaries, but if they must go in
the corners then full BSC is not a good idea.
Corner loading boosts upper bass and exaberbates room modes.
It makes it difficult for room gain to smoothly boost low bass only.
For the waveguide TMM the only way of simply removing BSC is
to omit the 0.5 way woofer completely and then tune it low to
go in the corner.
Using 0.5way TMM to go into corners is always going to be problematic.
The reduced BSC version of : http://www.zaphaudio.com/SR71.html
Is probably your best bet.
Its designed for 14L but using Zaphs specs you can go 22L tuned
to 35Hz, -3dB points are similar, less upper bass by a dB or so at
100Hz but -6dB point drops from 42Hz to 34Hz.
/sreten.
quoting Zaph himself :
The secret of good bass extension is use of room gain by placing
speakers away form the room boundaries, but if they must go in
the corners then full BSC is not a good idea.
Corner loading boosts upper bass and exaberbates room modes.
It makes it difficult for room gain to smoothly boost low bass only.
For the waveguide TMM the only way of simply removing BSC is
to omit the 0.5 way woofer completely and then tune it low to
go in the corner.
Using 0.5way TMM to go into corners is always going to be problematic.
The reduced BSC version of : http://www.zaphaudio.com/SR71.html
Is probably your best bet.
Its designed for 14L but using Zaphs specs you can go 22L tuned
to 35Hz, -3dB points are similar, less upper bass by a dB or so at
100Hz but -6dB point drops from 42Hz to 34Hz.
/sreten.Hey, someone else in Brighton!
The thing that has inspired replacing my current standmount speakers is moving from a small terraced house which provided plenty of room gain, to a large semi with knocked through lounge, dining room and kitchen, plus patio doors at one end and big windows at the other - i.e. practically zero room gain.
My concern with any single woofer design is the high demands on the woofers, especially when watching films, is not going to be conducive to clean sound or woofer durability.
How about an MTM using the Zaph waveguide TMM components (inc waveguide as that gets more tweeter sensitivity where it counts) and no BSC? Obviously the lowpass slope will need to be changed to deal with both woofers producing midrange.
Alex
The thing that has inspired replacing my current standmount speakers is moving from a small terraced house which provided plenty of room gain, to a large semi with knocked through lounge, dining room and kitchen, plus patio doors at one end and big windows at the other - i.e. practically zero room gain.
My concern with any single woofer design is the high demands on the woofers, especially when watching films, is not going to be conducive to clean sound or woofer durability.
How about an MTM using the Zaph waveguide TMM components (inc waveguide as that gets more tweeter sensitivity where it counts) and no BSC? Obviously the lowpass slope will need to be changed to deal with both woofers producing midrange.
Alex
Hi,
Room gain using unequal distance spacing to the room boundaries,
floor, side wall, rear wall, is not an option for corner placement.
Room modes are a different issue, corner placement exacerbates
them and essentially the bigger the room the lower they are, and
smooth deep bass extension is a difficult business, especially in
areas between the modes.
A subwoofer or two may be the answer to a large room and HT bass.
HT I'm not that up on, or how well stereo speakers cope with it.
40"x 9"x10" gives around 1.4 cuft / 40 L. this is appropriate for
deep vented bass from an 8" or 2 x 6.5" or 2 x 8" / 3 x 6.5"
sealed, the last option being a rather rigorous load.
BSC for such speaker is only partially compensated by corner placement,
the lower end lift, the upper end is still there and its complicated by
early reflections / dips from the near room boundaries. The ideal
corner speaker has controlled directivity (within possibilities).
FWIW the waveguided TMM would be a more reasonable option
if the tweeter was not running full tilt. However you can go to 2.7uF
on the tweeter and reduce the the 4mH on the 0.5 way woofer so
I guess it is one of your best options.
I'd put holes in the brace betwen the drivers and use a single vent.
Tune this to match the siting, I'd expect lower tuning would work.
Note that LFE subsonics will overload nearly all vented speakers
and a separate subwoofer is required for these HT effects.
/sreten.
Room gain using unequal distance spacing to the room boundaries,
floor, side wall, rear wall, is not an option for corner placement.
Room modes are a different issue, corner placement exacerbates
them and essentially the bigger the room the lower they are, and
smooth deep bass extension is a difficult business, especially in
areas between the modes.
A subwoofer or two may be the answer to a large room and HT bass.
HT I'm not that up on, or how well stereo speakers cope with it.
40"x 9"x10" gives around 1.4 cuft / 40 L. this is appropriate for
deep vented bass from an 8" or 2 x 6.5" or 2 x 8" / 3 x 6.5"
sealed, the last option being a rather rigorous load.
BSC for such speaker is only partially compensated by corner placement,
the lower end lift, the upper end is still there and its complicated by
early reflections / dips from the near room boundaries. The ideal
corner speaker has controlled directivity (within possibilities).
FWIW the waveguided TMM would be a more reasonable option
if the tweeter was not running full tilt. However you can go to 2.7uF
on the tweeter and reduce the the 4mH on the 0.5 way woofer so
I guess it is one of your best options.
I'd put holes in the brace betwen the drivers and use a single vent.
Tune this to match the siting, I'd expect lower tuning would work.
Note that LFE subsonics will overload nearly all vented speakers
and a separate subwoofer is required for these HT effects.
/sreten.
The BiB is designed for corner placement and has a large group of satisfied builders.
http://www.zillaspeak.com/bib.asp
http://www.diyaudio.com/forums/showthread.php?s=&threadid=66173
http://www.zillaspeak.com/bib.asp
http://www.diyaudio.com/forums/showthread.php?s=&threadid=66173
sreten said:
Ah, my understanding of room gain was that speaker placement was irrelevant and it was merely a gain of 12dB per octave at all wavelengths whose 1/2 wavelength is greater than the largest room dimension.
And then boundary reinforcement being 6dB gain in the wavelengths greater than 1/4 wavelength from the boundary, for each boundary (assuming perfect reflection), though obviously this only affects frequencies below the baffle step.
sreten said:
2 x 6.5"-7" vented seems the obvious choice due to optimal load on my amp and easier crossover to tweeter than a 8".
sreten said:
I presume this controlled directivity is only feasible with a fairly sizeable horn.
sreten said:
In this case you're referring to the tweeter not being padded back and is thus short on sensitivity if it were to be matched up with two woofers running in parallel through the midrange, correct? But with the waveguide it seems to have plenty of sensitivity even compared to the pair of woofers. The 2.7uF cap will lower the tweeter's highpass frequency to better match the two woofers' midrange. Would it be foolish to remove the 4mH inductor totally and run both woofers with just the single 0.7mH inductor in series with them, and place the woofers above and below the tweeter waveguide for good midrange integration?
sreten said:
I agree, even Zaph's experiments show there is no need to separate the two woofers internally. I'm amazed how little power handling hi-fi woofers have below 100Hz - compared to the Eminence 3015LF in a bass cab I'm building which can handle full RMS power (450W) and more down to the tuning frequency, they're hopeless! But few hi-fi woofers have 9.6mm Xmax...
Alex
P.S. The BiB is way too big for SWMBO to approve!
How about my ER18RNX/27TDFC MTM design?
http://www.geocities.com/woove99/Spkrbldg/ER18RNX_MTM_2Way.htm
I can easily change its BSC amount since it uses a simple 2-way xover.
The ER18RNX has exceptionally good power handling as a 7" hi-fi midwoofer, and lower distortions than other Seas Prestige 7" (e.g., CA18RNX), thanks to its improved motor. I think using this in MTM can meet your need.
http://www.geocities.com/woove99/Spkrbldg/ER18RNX_MTM_2Way.htm
I can easily change its BSC amount since it uses a simple 2-way xover.
The ER18RNX has exceptionally good power handling as a 7" hi-fi midwoofer, and lower distortions than other Seas Prestige 7" (e.g., CA18RNX), thanks to its improved motor. I think using this in MTM can meet your need.
Jay_WJ said:
That looks pretty much perfect! How would one tweak the BSC to compensate for placement? (I should point out that the speakers are not each in a corner, but the TV is in a corner and the speakers are either side, about 3' apart inside edge to inside edge, and about 6" from a wall each (but that wall is diagonally sloping inwards behind them)).
Alex
The best way is to adjust BSC in your room by your ear. In fact, this is what any sensible DIY speaker designers do to find a proper amount of BSC for each design, which is affected by multiple factors and cannot be quantifiable by measurement.
For this MTM design, it's very easy to adjust BSC yourself. Start with my default design which has pretty much full BSC. By listening, if you hear too much bass and/or too heavy tonal balance in midrange, you can reduce BSC by unwinding the inductor in the woofer network and adjusting the padding resistor in the tweeter network. Read my notes about voicing speakers:
http://www.geocities.com/woove99/Spkrbldg/DesigningXO.htm ("Voicing your speakers" section)
If you know the coil spec (gauge and the coil's physical size), the number of turns you need to take out to reach a certain value can be computed. I can do the calculation if you want.
For this MTM design, it's very easy to adjust BSC yourself. Start with my default design which has pretty much full BSC. By listening, if you hear too much bass and/or too heavy tonal balance in midrange, you can reduce BSC by unwinding the inductor in the woofer network and adjusting the padding resistor in the tweeter network. Read my notes about voicing speakers:
http://www.geocities.com/woove99/Spkrbldg/DesigningXO.htm ("Voicing your speakers" section)
If you know the coil spec (gauge and the coil's physical size), the number of turns you need to take out to reach a certain value can be computed. I can do the calculation if you want.
Let me throw out something from left field. This is an idea at this point, no one has developed it and no XO exists yet (a couple of projects including Tim Forman's latest indicate it is feasible)
Probably the new bass champ in smallish woofers is the CSS SDX7 (think next gen Extremis). With the XBL2 motor it has low distortion and goes low. 4 of these in a room will produce BASS.
Then take my current favorite tweeter -- the Fostex FF85k -- i think of it as a very good 3/4" tweeter with an overlarge surround (i admit i've not listened to a stock one yet). Fostex claims 32 kHz out of this, even if that is boastful, it still gets up there. The big thing is that you can XO it as low as 250-300 Hz (you can actually get an xMax limited 100 Hz out of it, but i only recommend that for use as a computer speaker).
2 SDX7 + FF85k would allow an MTM with an XO at or near the bafflestep. Both Tim & Al Wooley in his Apex III use the SDX7 up to 700 Hz -- 8.5" has an F3 for BS just below this, so one could just juggle things to get the BSC into the XO point. And with an XO that low, many of the issues with MTM go away.
dave
Probably the new bass champ in smallish woofers is the CSS SDX7 (think next gen Extremis). With the XBL2 motor it has low distortion and goes low. 4 of these in a room will produce BASS.
Then take my current favorite tweeter -- the Fostex FF85k -- i think of it as a very good 3/4" tweeter with an overlarge surround (i admit i've not listened to a stock one yet). Fostex claims 32 kHz out of this, even if that is boastful, it still gets up there. The big thing is that you can XO it as low as 250-300 Hz (you can actually get an xMax limited 100 Hz out of it, but i only recommend that for use as a computer speaker).
2 SDX7 + FF85k would allow an MTM with an XO at or near the bafflestep. Both Tim & Al Wooley in his Apex III use the SDX7 up to 700 Hz -- 8.5" has an F3 for BS just below this, so one could just juggle things to get the BSC into the XO point. And with an XO that low, many of the issues with MTM go away.
dave
planet10 said:
A good experimental design. The SDX7 is interesting. I hope our favorite testers measure it soon. If its linear/nonlinear distortions are (even slightly) better than the Extremis, it'll be a strong contender on the 7" market.
I don't know about the FF85K. Not sure if it can give cleaner sound than our favorite Seas tweeters above 1 kHz. Although it's a fullrange driver, I'd not cross it below 500 Hz LR4 or 700 Hz LR2 when used in a design with high xmax midwoofers.
Hi,
Steel sheet on the relevant side of the cabinet will reduce stray
magnetic field, the other option is fitting bucking magnets or of
course shielded drivers.
3 ft apart ? That just too close except for a small room and close
listening / viewing distance. Probably for such an arrangement
subs / satellites would be better then largish fullrange speakers.
I'm not sure what would be best, I'd say possibly slim floorstanders
with good dispersion to reduce localisation, but subs are needed.
/sreten.
Steel sheet on the relevant side of the cabinet will reduce stray
magnetic field, the other option is fitting bucking magnets or of
course shielded drivers.
3 ft apart ? That just too close except for a small room and close
listening / viewing distance. Probably for such an arrangement
subs / satellites would be better then largish fullrange speakers.
I'm not sure what would be best, I'd say possibly slim floorstanders
with good dispersion to reduce localisation, but subs are needed.
/sreten.sreten said:
Bit of an underestimate - more like 3'6" to 4' apart, inside cab edge to inside cab edge.
I'm in a bit of a dilemma - I'm realising the 7" MTM design will be possibly a little too visually imposing but it will have the dynamic capability and bottom I want, and presumably the larger cones will have less dispersion and thus fewer problems with side wall reflections than smaller woofers. It's also relatively simple, using my existing amp and a basic passive crossover.
On the other hand, maybe a very slim floorstander with TM design, using something like a 5" midbass would do the job, in a sealed box and designed to cross over to an active subwoofer. I was previously looking at adding a sub to my existing speakers using an XLS 830500 with a 200W plate amp.
Alternatively are there any full range designs that could work in a line array with such a sub?
Alex
Size of the midwoofer has nothing to do with the speaker's dispersion characteristic if the woofer is used with a xover frequency that is low enough to avoid its beaming effect.
If you want a seald design, 7" is a minimum size that can used with a subwoofer with 80 Hz xover. I wouldn't cross a sub higher than this.
You can build my ER18RNX/27TDFC MTM in a sealed cabinet that can be only 8" wide and less tall than my default design. It'll need a sand-filled bottom chamber to reduce the box volume, if you want a floorstander. Or you can build a standmounter. If you want to go this route, I can calculate an optimal volume for a sealed box for you.
If you want a seald design, 7" is a minimum size that can used with a subwoofer with 80 Hz xover. I wouldn't cross a sub higher than this.
You can build my ER18RNX/27TDFC MTM in a sealed cabinet that can be only 8" wide and less tall than my default design. It'll need a sand-filled bottom chamber to reduce the box volume, if you want a floorstander. Or you can build a standmounter. If you want to go this route, I can calculate an optimal volume for a sealed box for you.
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