[JimC]

My sub (a Velodyne F-1800RII), includes line-level inputs and outputs
which permit high-frequency signals to be filtered out and sent through
the line-level outputs to the power amp, essentially removing the bass
from the signal fed to the power amp and providing bi-amplification.
There is a high-pass filter switch which can be set to either 80Hz or
100Hz (6 dB/octave). There is also a variable frequency low-pass filter
which can be adjusted between 40Hz and 120Hz (12 dB/octave initial,
48dB/octave ultimate).

My question is: Assuming the low-pass crossover is set to 40Hz, and the
high-pass filter is set to 80Hz, what happens to the frequencies between
40Hz and 80Hz (Ignoring signals that are outside the roll-off curves)?
Are they simply lost? In this system, the mains are Maggie 3.6 planars,
with response extending somewhat below 40Hz, and I would prefer to feed
bass above that frequency to the Maggies rather than have them
reproduced by the subwoofer. But with the above system, it seems that
they would not receive any substantial bass below 80Hz. Also, what
happens to signals sent to the mains when the Velodyne low-pass
crossover is adjusted, e.g., adjusted between 40Hz and 80Hz or above?

Presently I am not using the high-pass connections, and instead feed the
full audio frequency spectrum directly to both the sub and the power amp
(the preamp output is connected directly to the power amp and to the
sub). This is because I had concluded that signals fed directly from the
preamp to the power amp, without any processing or filtering, would be
cleaner and provide a more transparent sound from the Maggies. On the
other hand, it might be beneficial to remove the very low frequencies
from the amp and the Maggies for greater efficiency.

Any advice or suggestions? Do I need an external electronic crossover to
resolve this issue?

Jim

[Arny Krueger]

"JimC" wrote in message


My question is: Assuming the low-pass crossover is set to
40Hz, and the high-pass filter is set to 80Hz, what
happens to the frequencies between 40Hz and 80Hz
(Ignoring signals that are outside the roll-off curves)?

They get attenuated.

Are they simply lost?

Well, reduced.

In this system, the mains are
Maggie 3.6 planars, with response extending somewhat
below 40Hz, and I would prefer to feed bass above that
frequency to the Maggies rather than have them reproduced
by the subwoofer.

Why?

But with the above system, it seems
that they would not receive any substantial bass below
80Hz.

Most analog filters such as these have relatively gentle roll-offs. At the
corner frequency (in this case 80 Hz) the filter response is only 3 dB down.
Below that frequency, response rolls off fairly gently. It's not like
signals below 80 Hz are lost - they are simply attenuated a modest amount.

Any discussion of filters for the purpose of crossing-over loudspeakers has
to include the acoustic response of the loudspeakers, which includes room
effects. I don't think that those are exactly known at this time.

For example, if there is a peak in room response in the 40-60 Hz range, the
slight depression caused by the separation of crossover frequencies might be
filled-in by the peak.

Also, what happens to signals sent to the mains
when the Velodyne low-pass crossover is adjusted, e.g.,
adjusted between 40Hz and 80Hz or above?

Usually, there is no effect at all.

Presently I am not using the high-pass connections, and
instead feed the full audio frequency spectrum directly
to both the sub and the power amp (the preamp output is
connected directly to the power amp and to the sub).

That seems to avoid some of the benefit of the subwoofer. I would expect a
peak in response where the subwoofer and the mains overlap, unless there was
a polarity problem. Then there would be a dip. But, I don't know anything at
all about room response, and it is very significant.

This
is because I had concluded that signals fed directly from
the preamp to the power amp, without any processing or
filtering, would be cleaner and provide a more
transparent sound from the Maggies.

Maybe yes, but probably no.

On the other hand, it
might be beneficial to remove the very low frequencies
from the amp and the Maggies for greater efficiency.

More to the point, the maggies may not be as linear at low frequencies. As a
rule, most speakers sound cleaner and tighter when the very lowest
frequencies are filtered out. Applying a low pass filter to a subwoofer
often helps reduce thuddiness and boominess. Usually, low pass and high
pass filters used in a situation like this are set to the same frequency.

Any advice or suggestions? Do I need an external
electronic crossover to resolve this issue?

It seems like the crossover on the Velodyne would be adequate for many
applications. I think you should try to exploit it before buying more
equipment. As a rule, low and high pass filters are set for the same corner
frequency.

[JimC]

Arny Krueger wrote:
"JimC" wrote in message



My question is: Assuming the low-pass crossover is set to
40Hz, and the high-pass filter is set to 80Hz, what
happens to the frequencies between 40Hz and 80Hz
(Ignoring signals that are outside the roll-off curves)?


They get attenuated.


Are they simply lost?


Well, reduced.


In this system, the mains are
Maggie 3.6 planars, with response extending somewhat
below 40Hz, and I would prefer to feed bass above that
frequency to the Maggies rather than have them reproduced
by the subwoofer.


Why?

Why? Among other considerations, because I like the Maggie's response
above around 50Hz to 60Hz and wouldn't want to simply throw it away.

Incidentally, I have ordered one of the Paradigm X30 active crossovers,
and I'll report on the results of using it with the Velodyne to remove
the low bass otherwise sent to the maggies.

Also, I didn't get a response to my questions regarding the use of one
of the new HDMI 1.3 pre/pros or AVRs with Audyssey processors or
equivalent, which can also provide bass management. Would one of these
systems perform the same functions (crossover and bass management) as an
active crossover?

Jim

Jim

[[email protected]]

On Mar 10, 12:51*am, JimC wrote:
My sub (a Velodyne F-1800RII), includes line-level inputs and outputs
which permit high-frequency signals to be filtered out and sent through
the line-level outputs to the power amp, essentially removing the bass
from the signal fed to the power amp and providing bi-amplification.
There is a high-pass filter switch which can be set to either 80Hz or
100Hz (6 dB/octave). There is also a variable frequency low-pass filter
which can be adjusted between 40Hz and 120Hz (12 dB/octave initial,
48dB/octave ultimate).

My question is: Assuming the low-pass crossover is set to 40Hz, and the
high-pass filter is set to 80Hz, what happens to the frequencies between
40Hz and 80Hz (Ignoring signals that are outside the roll-off curves)?
Are they simply lost? *In this system, the mains are Maggie 3.6 planars,
with response extending somewhat below 40Hz, and I would prefer to feed
bass above that frequency to the Maggies rather than have them
reproduced by the subwoofer. *But with the above system, it seems that
they would not receive any substantial bass below 80Hz. Also, what
happens to signals sent to the mains when the Velodyne low-pass
crossover is adjusted, e.g., adjusted between 40Hz and 80Hz or above?

Presently I am not using the high-pass connections, and instead feed the
full audio frequency spectrum directly to both the sub and the power amp
(the preamp output is connected directly to the power amp and to the
sub). This is because I had concluded that signals fed directly from the
preamp to the power amp, without any processing or filtering, would be
cleaner and provide a more transparent sound from the Maggies. On the
other hand, it might be beneficial to remove the very low frequencies
from the amp and the Maggies for greater efficiency.

Any advice or suggestions? Do I need an external electronic crossover to
resolve this issue?

Jim

Are you sure the two crossovers are related to each other? Does the
sub also have speaker thru-puts as well? Is it possible that the
80/100 filter is part of connecting speaker outputs directly to the
sub and then connecting from the sub to the front speakers? And the
40-120hz filter is part of the low level input?

[Dave]

wrote in message
...
Are you sure the two crossovers are related to each other? Does the
sub also have speaker thru-puts as well? Is it possible that the
80/100 filter is part of connecting speaker outputs directly to the
sub and then connecting from the sub to the front speakers? And the
40-120hz filter is part of the low level input?

These filters are similar if not identical on almost all low and mid-level
Velodyne subs, regardless of whether or not they have speaker-level inputs
or not. Both filters affect both sets of inputs. I recall posting a pretty
similar question here a few years back. Never was completely happy with the
answer(s). I don't see why Velodyne doesn't just have a variable high-pass
filter like the low-pass, which affords the user better control when trying
to integrate the sub with an existing loudspeaker system... obviously with a
servo sub like the F1800 which in its day probably cost $2000, cost was
likely not the reason.

Dave

[jamesgangnc[_3_]]

"Dave" wrote in message
...
wrote in message
...
Are you sure the two crossovers are related to each other? Does the
sub also have speaker thru-puts as well? Is it possible that the
80/100 filter is part of connecting speaker outputs directly to the
sub and then connecting from the sub to the front speakers? And the
40-120hz filter is part of the low level input?

These filters are similar if not identical on almost all low and mid-level
Velodyne subs, regardless of whether or not they have speaker-level inputs
or not. Both filters affect both sets of inputs. I recall posting a
pretty
similar question here a few years back. Never was completely happy with
the
answer(s). I don't see why Velodyne doesn't just have a variable
high-pass
filter like the low-pass, which affords the user better control when
trying
to integrate the sub with an existing loudspeaker system... obviously with
a
servo sub like the F1800 which in its day probably cost $2000, cost was
likely not the reason.

Dave

It's a bit more work to have a decent filter on the high side if it is
really filtering the low out before the lines go on to the front speakers.
Though a 6 db one is just probably a coil. The other filter maybe doesn't
get applied to the high outputs? I don't know what a "12db initial 48db
ultimate is but I'm doubting they have a high output 48db filter for the
front speaker outs? Anyone actually seen the schematic on one of these?

[George Flanagin]

On Mon, 10 Mar 2008 04:51:13 +0000, JimC wrote:

Any advice or suggestions? Do I need an external electronic crossover to
resolve this issue?


I think even a basic external xover is a worthwhile investment --- try a
cheap one and decide for yourself.

I use an Ashly XR1001 ($US300?) to divide the signal between my QUAD ESL
988s and a Meridian M2500 subwoofer. The Ashly allows you to choose the
corner frequencies of the high and low pass filters, and it also allows
you to choose the degree to which you want the frequency span in the
overlap to be exactly flat, slightly elevated, or slightly attenuated.
This will take care of most of the room abnormalities that Arny mentioned.

I have two other pairs of speakers (Celestion SL700SE & QUAD 12L Active)
that I occasionally use. After measuring, I wrote down the three separate
xover settings on an index card, and taped it to the top of the xover.
Rapid set up when switching speakers is now possible.

Inside the unit (i.e., no front panel control) is a switchable 20Hz high
pass that allows you to filter out the dreadful rumble in many concert
halls, now faithfully brought to us through (SA)CDs.

Regards,

George

[Sonnova]

On Sun, 16 Mar 2008 21:33:44 -0700, George Flanagin wrote
(in article ):

On Mon, 10 Mar 2008 04:51:13 +0000, JimC wrote:

Any advice or suggestions? Do I need an external electronic crossover to
resolve this issue?


I think even a basic external xover is a worthwhile investment --- try a
cheap one and decide for yourself.

I use an Ashly XR1001 ($US300?) to divide the signal between my QUAD ESL
988s and a Meridian M2500 subwoofer. The Ashly allows you to choose the
corner frequencies of the high and low pass filters, and it also allows
you to choose the degree to which you want the frequency span in the
overlap to be exactly flat, slightly elevated, or slightly attenuated.
This will take care of most of the room abnormalities that Arny mentioned.

I have two other pairs of speakers (Celestion SL700SE & QUAD 12L Active)
that I occasionally use. After measuring, I wrote down the three separate
xover settings on an index card, and taped it to the top of the xover.
Rapid set up when switching speakers is now possible.

Inside the unit (i.e., no front panel control) is a switchable 20Hz high
pass that allows you to filter out the dreadful rumble in many concert
halls, now faithfully brought to us through (SA)CDs.

Regards,

George

This is a question, not an implied criticism (I haven't tried an active
crossover). Don't you find that all of that extra circuitry (and another
round trip of A/D and D/A - I assume the Ashly uses DSP for the filters)
muddies the sound? I would think that it would.

[George Flanagin]

On Mon, 17 Mar 2008 23:06:23 +0000, Sonnova wrote:

On Sun, 16 Mar 2008 21:33:44 -0700, George Flanagin wrote (in article
):


This is a question, not an implied criticism (I haven't tried an active
crossover). Don't you find that all of that extra circuitry (and another
round trip of A/D and D/A - I assume the Ashly uses DSP for the filters)
muddies the sound? I would think that it would.

If you look he (http://www.ashly.com/product/xr-series-2.htm) you will
note that the Ashly is an analog domain crossover.

I will tell you a story about its profound effect on the sound. A dealer
came by my house to take a listen to the QUAD ESL 988s. He seemed to enjoy
the sound, or at least he was being polite about what he heard. A few
weeks later he overheard me discussing the Ashly with another hifi
enthusiast, and he commented on the way that all line level crossovers
always introduce some harshness in the region of the upper octave of the
piano (2-4 KHz).

What amazed me is that the Ashly did not arrive at my house until three
days /after/ the dealer heard the system, and I did not yet have my
subwoofer in circuit although it was in the room. So, apparently the Ashly
influenced the sound while it was still on the UPS truck. I showed him the
shipment tag, and he still didn't believe me.

My opinion is that the sound is fine, and I find it musically satisfying.
I feel that feeding a bunch of low notes to the speakers when they can't
accurately reproduce them is bound to be detrimental to the sound --- just
forcing the electrostatic membranes to "flap around in the breeze," so to
speak.

Regards,

george