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Old 21st January 2008, 03:11 PM   #1
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Default Floorstanders either side of TV in room corner?

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
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Old 21st January 2008, 03:16 PM   #2
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The need for baffle step is determined mostly by the drivers and the baffle width. It sounds like you will need these to be fairly skinny speakers? If so you may have to add the BSC but corner loading will tend to offset that.

What sort of drivers are you looking at Alex? (size, number etc.)
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Old 21st January 2008, 03:33 PM   #3
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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
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Old 21st January 2008, 04:19 PM   #4
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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.
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Old 22nd January 2008, 10:40 AM   #5
sreten is offline sreten  United Kingdom
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Hi,

quoting Zaph himself :

Quote:
As far as using the reduced BSC filter in the floorstanding tower, I wouldn't do it
unless you're going to do something stupid like place the speaker in a corner.
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.
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Old 22nd January 2008, 11:53 AM   #6
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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
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Old 23rd January 2008, 09:30 AM   #7
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Been looking at the Zaph MTM floorstander design but the woofers aren't as good at lows as those in the TMM, so an MTM variation on the TMM would make sense. Anyone have any ideas on that?

Alex
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Old 23rd January 2008, 10:24 AM   #8
sreten is offline sreten  United Kingdom
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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.
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Old 23rd January 2008, 11:05 AM   #9
kaan is offline kaan  Denmark
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The BiB is designed for corner placement and has a large group of satisfied builders.

http://www.zillaspeak.com/bib.asp

Terry Cain's BIB -why does it work and does anyone have those Fostex Craft Handbooks?
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Old 23rd January 2008, 06:50 PM   #10
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Quote:
Originally posted by sreten
Room gain using unequal distance spacing to the room boundaries,
floor, side wall, rear wall, is not an option for corner placement.
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.

Quote:
Originally posted by sreten
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.
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".

Quote:
Originally posted by sreten
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).
I presume this controlled directivity is only feasible with a fairly sizeable horn.

Quote:
Originally posted by sreten
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.
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?

Quote:
Originally posted by sreten
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.
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!
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