Low-pass filter thoughts
 

In article ,
Wally wrote:
Don't think you'd find any problems sourcing NE5534AN - Maplin stock
them.

I haven't looked for them yet - found a Phillips data sheet that said hey
were discontinued, so assumed they might be hard to find.

Could be that refers to an 'N' suffix.

--
*Growing old is inevitable, growing up is optional *

Dave Plowman London SW
To e-mail, change noise into sound.

Low-pass filter thoughts
 

Pooh Bear wrote:



Wally wrote:

As some of you may be aware, I have an on-going speaker rebuild fantasy
bubbling away in the background. The plan is to bi-amp, and part of this
involves a second line output on the pre-amp, to send a signal to the
bass amp. The bass/midrange driver will have no high-pass components in
the crossover - I intend to let the bass roll off naturally, and try to
match the low-pass filter feeding the subs to this roll-off. I'm edging
towards trying to make a prototype filter and would welcome comments...

The pre-amp is a Cambridge A75. The chips it uses are NE5534N op-amps,
evidently low-noise and suitable for high quality audio. My intention was
to use the same chips for my active filter / output stage, on the
assumption that the pre-amp's PSU will be delivering the right
voltage(s). However, it looks like these chips are no longer made - what
would be a suitable alternative?

5534s are most certainly still made. What made you think they aren't ?


Available from many places. Best audio op amp ever made IMHO. Try Maplins
for starters.

Ian

--
Ian Bell

Low-pass filter thoughts
 

Wally wrote:

As some of you may be aware, I have an on-going speaker rebuild fantasy
bubbling away in the background. The plan is to bi-amp, and part of this
involves a second line output on the pre-amp, to send a signal to the bass
amp. The bass/midrange driver will have no high-pass components in the
crossover - I intend to let the bass roll off naturally, and try to match
the low-pass filter feeding the subs to this roll-off. I'm edging towards
trying to make a prototype filter and would welcome comments...

The pre-amp is a Cambridge A75. The chips it uses are NE5534N op-amps,
evidently low-noise and suitable for high quality audio. My intention was to
use the same chips for my active filter / output stage, on the assumption
that the pre-amp's PSU will be delivering the right voltage(s). However, it
looks like these chips are no longer made - what would be a suitable
alternative?

I know next to nothing about solid state electronics, but my efforts so far
would suggest that I want to use an integrator and a phase inverter. The
integrator provides the actual filtering effect (I think), but is 180
degrees out at the crossover, decreasing to 90 degrees lower down. It would
seem to be a good thing to try and get the subs to be in phase at the point
where they cross over the natural roll-off of the bass/mid drivers/cabs. So,
I reckon the active filter and a phase inverter will do the trick - that
should give me zero degrees shift at crossover, and 90 degrees lag somewhere
low down. (I'm considering a crossover point at something around 60-80Hz.)

Does this sound like it should work?


No.

As you know nothing about electronics you should start with this:

http://www.bmm-electronics.com/Product.asp?Product_ID=7

You really are better off with steep high and low pass filters.
trying to match the hf response of a sub to the lf response of a
mid-range box is difficult, and putting a lot of power through the
mid-range below its resonant frequency is asking for trouble.

--
Eiron.

Low-pass filter thoughts
 

Eiron wrote:

You really are better off with steep high and low pass filters.
trying to match the hf response of a sub to the lf response of a
mid-range box is difficult, and putting a lot of power through the
mid-range below its resonant frequency is asking for trouble.

The 'midrange' is a KEF B110, which I believe has a sufficiently low
resonant frequency to serve as a bass driver as well.


--
Wally
www.artbywally.com
www.wally.myby.co.uk

Low-pass filter thoughts
 

On Mon, 18 Oct 2004 20:13:32 +0100, "Wally"
wrote:

hi.
have a look at this http://www.linkwitzlab.com/
theres lots of info here
regards
bob

Low-pass filter thoughts
 

Wally wrote:

Eiron wrote:


You really are better off with steep high and low pass filters.
Trying to match the hf response of a sub to the lf response of a
mid-range box is difficult, and putting a lot of power through the
mid-range below its resonant frequency is asking for trouble.


The 'midrange' is a KEF B110, which I believe has a sufficiently low
resonant frequency to serve as a bass driver as well.

I'm listening to one at the moment.
I like them but Stuart P thinks that the sound from a Bextrene cone
collapses at low levels.

Here are some specs for a typical box using the B110:
http://www.mhennessy.f9.co.uk/rogers/ls35a_page4.jpg

If you use an open baffle or reflex box then the cone will flap about
dangerously at moderate power levels (without a high-pass filter)
You should be OK with a closed box and up to a 100w amp
but I would still recommend a 2-way 4th-order Linkwitz-Riley crossover
at 100hz or higher.

--
Eiron.

Low-pass filter thoughts
 

"Dave Plowman (News)" wrote:

In article ,
Wally wrote:
Don't think you'd find any problems sourcing NE5534AN - Maplin stock
them.

I haven't looked for them yet - found a Phillips data sheet that said hey
were discontinued, so assumed they might be hard to find.

Could be that refers to an 'N' suffix.


Somewhat strangely it seems that Philips *have* discontinued it !

http://www.semiconductors.philips.co...E5534_A_2.html

See note and link towards the bottom of the page.

TI and JRC still make them I'm sure - and the 5532 as well.


Graham

Low-pass filter thoughts
 

On Wed, 20 Oct 2004 22:39:33 +0100, Ian Bell
wrote:

Pooh Bear wrote:

Wally wrote:

As some of you may be aware, I have an on-going speaker rebuild fantasy
bubbling away in the background. The plan is to bi-amp, and part of this
involves a second line output on the pre-amp, to send a signal to the
bass amp. The bass/midrange driver will have no high-pass components in
the crossover - I intend to let the bass roll off naturally, and try to
match the low-pass filter feeding the subs to this roll-off. I'm edging
towards trying to make a prototype filter and would welcome comments...

The pre-amp is a Cambridge A75. The chips it uses are NE5534N op-amps,
evidently low-noise and suitable for high quality audio. My intention was
to use the same chips for my active filter / output stage, on the
assumption that the pre-amp's PSU will be delivering the right
voltage(s). However, it looks like these chips are no longer made - what
would be a suitable alternative?

5534s are most certainly still made. What made you think they aren't ?

Available from many places. Best audio op amp ever made IMHO. Try Maplins
for starters.

If it's good enough for Meridian output stages, then it's good enough
for me! :-)
--

Stewart Pinkerton | Music is Art - Audio is Engineering

Low-pass filter thoughts
 

In article , Wally
wrote:
Jim Lesurf wrote:

Have a look at some of the pages on filters in the 'Scots Guide'. This
inlcudes some basic stuff on designing simple filters with ICs.

Scots Guide? One of your pages?

Erm... Hundreds, actually. ;-)

Have a look at the 'Scots Guide' address in my sig, below. When there, go
to the section on 'Analog and Audio', and you will then find a link to some
pages on active filters. There are bits on related topics scattered around
the 'Guide'.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

Low-pass filter thoughts
 

Stewart Pinkerton wrote:

If it's good enough for Meridian output stages, then it's good enough
for me! :-)

They're in the 203? That means that my audio signal goes through nothing but
5534s before hitting the valves (which are soaked in swamp water to give 'em
soul...).


--
Wally
www.artbywally.com
www.wally.myby.co.uk