Crossover questions.....
 

On Wed, 17 Jan 2007 18:20:24 GMT, (Don Pearce)
wrote:

as they are a little larger and have easy, front access - see the original
drivers on a nice, easily removed front baffle he

http://www.apah69.dsl.pipex.com/show/originals.JPG


H3310s looks like a Seas pat number, but I can't find any info,
particularly the TS parameters, so I can't offer any help on box
design.

Ah - quite by chance I find that H3310s is not a driver, it is the
part number for the rubber surround, which is used on several drivers.
If you can find another part number somewhere, we might progress.

d

--
Pearce Consulting
http://www.pearce.uk.com

Crossover questions.....
 

Keith G wrote:
"Don Pearce" wrote


Without being able to trace the circuits I can't say for definite, but
that looks like a second order crossover. Are those chokes wound on
ferrite? If they are, this crossover has a power limit set by the
magnetic saturation of the ferrite. Your other one is a better way of
making a crossover choke.


OK, here's a pic of both sides of that crossover:

No, here's a couple of pix showing each side of that crossover:

http://www.apah69.dsl.pipex.com/show/topside.JPG

http://www.apah69.dsl.pipex.com/show/underside.JPG


The game plan is as follows:

Dr Rob very kindly gave me these speakers

http://www.apah69.dsl.pipex.com/show/donor.JPG

which sound fine but are easily beat by most (all, actually) of the other
spreakers I have here, due to a lack of any bass at all. I want to pull the
drivers (T27s and H3310s) out of 'em and use them in these boxes:

http://www.apah69.dsl.pipex.com/show/boxes.JPG

as they are a little larger and have easy, front access - see the original
drivers on a nice, easily removed front baffle he

http://www.apah69.dsl.pipex.com/show/originals.JPG


(Rob - speak now if you would rather have these back instead of me
cannabalising them!)


Go for it Keith!

They are my firstborn - I auditioned them in a Nottingham hifi shop in
1982 next to some AR18s and Wharfedale wotnots. I loved them for quite a
while - superb upper bass/mid and a nice treble from the T27s. I found
deep bass fine - certainly better than the other smallish budget
speakers of the time. The make is/was LNB, and they were about 100UKP (I
paid 40; mean then as now). On bass - check they're wired properly from
the xover to the terminals. I lent them to a friend for about 5 years,
and he fiddled about with them and put some different terminals on. When
I got them back they sounded terrible - on closer investigation he'd
wired them up incorrectly. I may have buggered that up as well ;-)



The idea is to fit the drivers into the boxes (which I will modify hugely
with a second skin and some crossbracing) using the Ruark crossover, leaving
Rob's 'donor' speakers as intact as possible (for a possible
reversal/restoration) and trying a few different drivers (if necessary)
until I can convince myself I have a pair of unique, stunning 'homebrew'
standmounters that blow away any commercial equivalent at many times the
price.....

;-)

(Or find, for only a little work, if I'm ****ing in the breeze!!)


Live the dream Keith :-)

You can bin them so far as I'm concerned. I thought you might be
interested in the xovers and the T27s. I thought the design was
intriguing (a compact transmission line) at the time, but in the real
world they can't hold a candle to Dynaudio 42s IMO. One last lease of
life in '25th Anniversary Edition' guise won't hurt :-)

Rob

Crossover questions.....
 

"Don Pearce" wrote in message
...
On Wed, 17 Jan 2007 18:20:24 GMT, (Don Pearce)
wrote:

as they are a little larger and have easy, front access - see the
original
drivers on a nice, easily removed front baffle he

http://www.apah69.dsl.pipex.com/show/originals.JPG


H3310s looks like a Seas pat number, but I can't find any info,
particularly the TS parameters, so I can't offer any help on box
design.

Ah - quite by chance I find that H3310s is not a driver, it is the
part number for the rubber surround, which is used on several drivers.
If you can find another part number somewhere, we might progress.



OK, Rob has kindly given me a Ticket To Ride so I'll get amongst 'em
tomorrow with a bit of luck! (****, I'll be glad when Swim ****es off to
work again - she's been on holiday for a month now and my totally
self-absorbed routine is shot to ****!!)

Anyway, by way of appreciation for yours and Serge's kind assistance, here's
a little treat for you:

You may well have heard plenty of music which is a load of balls, well here
is a load of balls which is music:

http://www.apah69.dsl.pipex.com/show...al%20Balls.wmv

Enjoy! :-)

(Never mind ports - fancy *tuning* that lot..?? ;-)

Crossover questions.....
 

"Rob" wrote in message
...
Keith G wrote:



(Rob - speak now if you would rather have these back instead of me
cannabalising them!)


Go for it Keith!


Cheers Rob!

:-)



They are my firstborn - I auditioned them in a Nottingham hifi shop in
1982 next to some AR18s and Wharfedale wotnots. I loved them for quite a
while - superb upper bass/mid and a nice treble from the T27s. I found
deep bass fine - certainly better than the other smallish budget speakers
of the time. The make is/was LNB, and they were about 100UKP (I paid 40;
mean then as now). On bass - check they're wired properly from the xover
to the terminals. I lent them to a friend for about 5 years, and he
fiddled about with them and put some different terminals on. When I got
them back they sounded terrible - on closer investigation he'd wired them
up incorrectly. I may have buggered that up as well ;-)


For now I'll just lift the drivers to try them in the gash rig I intend
trying!

(Reversible, if need be, in the short term...!!)


(Or find, for only a little work, if I'm ****ing in the breeze!!)


Live the dream Keith :-)

You can bin them so far as I'm concerned. I thought you might be
interested in the xovers and the T27s. I thought the design was intriguing
(a compact transmission line) at the time, but in the real world they
can't hold a candle to Dynaudio 42s IMO. One last lease of life in '25th
Anniversary Edition' guise won't hurt :-)



It'll be interesting to try and get a decent get a squeak out of 'em - I'm
never one to let science stand in the way of a bit of 'trilanerra' but the
only way I could ever learn is by doing/sweeping up the mess/doing again &c.
&c....!!

;-)

Crossover questions.....
 

Serge Auckland wrote:
Don Pearce wrote:

Without being able to trace the circuits I can't say for definite, but
that looks like a second order crossover. Are those chokes wound on
ferrite? If they are, this crossover has a power limit set by the
magnetic saturation of the ferrite. Your other one is a better way of
making a crossover choke.

Completely agree.

Are there any real test results showing the difference between
air and ferrite cored inductors in a crossover or is it another
evanescent chalk and cheese effect?

--
Eiron.

Crossover questions.....
 

Keith G wrote:
OK, some techie questions regarding this crossover:

http://www.apah69.dsl.pipex.com/show/crossover1.JPG


1) Anybody care to tell me what order it is (seems pretty basic to me)?

It looks like first order with impedance compensation on the bass. The
bass unit is probably 4 ohms. First order on the HF as well with about
3dBs attenuation. The tweeter is 8 ohms.
2) Can I slap it between just about any tweeter and similar sized mid/bass
unit with good effect?

You haven't got a hope in hell. You are doomed to disappointment.
3) Will a different box size have any bearing on how it works with the drivers?

Yes, but in the context of what you are trying to do, it's irrelevant.
4) Have I marked up the driver connections correctly?


Probably, but without knowing what the system is, it's impossible to say.

The Veroboard construction of the other crossovers should tell you
something. I'd guess that Falcon Acoustics supplied the components.

Stephen

Crossover questions.....
 

Eiron wrote:
Serge Auckland wrote:
Don Pearce wrote:

Without being able to trace the circuits I can't say for definite, but
that looks like a second order crossover. Are those chokes wound on
ferrite? If they are, this crossover has a power limit set by the
magnetic saturation of the ferrite. Your other one is a better way of
making a crossover choke.

Completely agree.

Are there any real test results showing the difference between
air and ferrite cored inductors in a crossover or is it another
evanescent chalk and cheese effect?


The difference between ferrite and air is the magnetic flux that each
coil can take before saturating. Ferrite is used as it results in
smaller coils and can use thinner wire for the same resistance or keep
the same thickness and have lower resistance and hence better Q. The
downside is that it takes a lot to saturate air whilst ferrite is
relatively easily saturated. I'll see if I can find my old college notes
regarding the actual differences.

S.

Crossover questions.....
 

Eiron wrote:

Are there any real test results showing the difference between
air and ferrite cored inductors in a crossover or is it another
evanescent chalk and cheese effect?

The distortion of ferrite cored inductors is measurable. Air cored coils
don't distort.

Stephen

Crossover questions.....
 

On Wed, 17 Jan 2007 20:25:18 +0000, Eiron wrote:

Serge Auckland wrote:
Don Pearce wrote:

Without being able to trace the circuits I can't say for definite, but
that looks like a second order crossover. Are those chokes wound on
ferrite? If they are, this crossover has a power limit set by the
magnetic saturation of the ferrite. Your other one is a better way of
making a crossover choke.

Completely agree.

Are there any real test results showing the difference between
air and ferrite cored inductors in a crossover or is it another
evanescent chalk and cheese effect?

I can't think of any, but the signal levels involved are similar to
those in valve output transformers - think how big they have to be to
achieve even their limited degree of linearity. The parallel is not
exact, of course, because these are rods, not closed cores, so in
essence they incorporate a huge air gap. Nevertheless you are dragging
the magnetic flux up and down the standard B/H curve of a piece of
magnetic material, and that just can't be as good as using plain air.

d

--
Pearce Consulting
http://www.pearce.uk.com

Crossover questions.....
 

"Keith G" wrote in message
...

OK, some techie questions regarding this crossover:

http://www.apah69.dsl.pipex.com/show/crossover1.JPG


1) Anybody care to tell me what order it is (seems pretty basic to me)?

**First order, with a Zobel on the bass driver.


2) Can I slap it between just about any tweeter and similar sized mid/bass
unit with good effect?


**Nope. Well, unless you are really, REALLY lucky. Figure on about a 1 in
100,000 shot of getting an excellent result.


3) Will a different box size have any bearing on how it works with the
drivers?

**A little.


4) Have I marked up the driver connections correctly?

**Possibly.


--
Trevor Wilson
www.rageaudio.com.au



--
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