There are only two ways to skin a rabbit....
 

.....either you do it or you get somebody else to, but there's any number of
ways to attenuate a rampant 'vinyl' signal it seems (pending the arrival of
some Alps pots - see elsewhere)!

See this whole side recording I did last night:

http://www.moirac.adsl24.co.uk/showntell/Marlene-AT.jpg

And here's the same side I did just now:

http://www.moirac.adsl24.co.uk/shown...ne-Ortofon.jpg

The *only* thing that is different between the two recordings is the cart I
used in each case - the first one is an AT OC5 with an output of 0.4mV; the
second is an Ortofon MC200U with an output of only 0.09mV!

Surprising, ain't it? I thought it might work but not to such an extent!!

:-)

OK, that's all - back to what you were doing!!

There are only two ways to skin a rabbit....
 

On Tue, 20 Oct 2009 16:43:34 +0100, "Keith G"
wrote:

....either you do it or you get somebody else to, but there's any number of
ways to attenuate a rampant 'vinyl' signal it seems (pending the arrival of
some Alps pots - see elsewhere)!

See this whole side recording I did last night:

http://www.moirac.adsl24.co.uk/showntell/Marlene-AT.jpg

And here's the same side I did just now:

http://www.moirac.adsl24.co.uk/shown...ne-Ortofon.jpg

The *only* thing that is different between the two recordings is the cart I
used in each case - the first one is an AT OC5 with an output of 0.4mV; the
second is an Ortofon MC200U with an output of only 0.09mV!

Surprising, ain't it? I thought it might work but not to such an extent!!

:-)

OK, that's all - back to what you were doing!!



Why did you leave that first one slamming so hard for a whole side? I
presume the two big blips in the second one were scratches.

d

There are only two ways to skin a rabbit....
 

"Don Pearce" wrote in message
...
On Tue, 20 Oct 2009 16:43:34 +0100, "Keith G"
wrote:

....either you do it or you get somebody else to, but there's any number
of
ways to attenuate a rampant 'vinyl' signal it seems (pending the arrival
of
some Alps pots - see elsewhere)!

See this whole side recording I did last night:

http://www.moirac.adsl24.co.uk/showntell/Marlene-AT.jpg

And here's the same side I did just now:

http://www.moirac.adsl24.co.uk/shown...ne-Ortofon.jpg

The *only* thing that is different between the two recordings is the cart
I
used in each case - the first one is an AT OC5 with an output of 0.4mV;
the
second is an Ortofon MC200U with an output of only 0.09mV!

Surprising, ain't it? I thought it might work but not to such an extent!!

:-)

OK, that's all - back to what you were doing!!



Why did you leave that first one slamming so hard for a whole side?



I didn't 'leave it slamming'! I have no way of attenuating the signal 'til I
get the Alps and fix my 'pot in a box' - is what my whole previous thread
was about!!



; presume the two big blips in the second one were scratches.


No, the record isn't scratched; they are 'pops' - and sound like this
(actual):

First one: http://www.moirac.adsl24.co.uk/showntell/Pop1.mp3

Second one: http://www.moirac.adsl24.co.uk/showntell/Pop2.mp3


They are easily fixed - I 'draw' through them with a 'pencil' or even draw
the wave by hand in Sound Forge - see Before and After on the first pop
he

http://www.moirac.adsl24.co.uk/showntell/Pop1Before.jpg

http://www.moirac.adsl24.co.uk/showntell/Pop1After.jpg

Good, innit?

****, my posts are *comprehensive and entertaining* are they not...??

;-)

There are only two ways to skin a rabbit....
 

In article ,
Keith G wrote:
I didn't 'leave it slamming'! I have no way of attenuating the signal
'til I get the Alps and fix my 'pot in a box' - is what my whole
previous thread was about!!

Make an attenuator out of fixed resistors. Only reason to go for a posh
pot is the channel balance is likely better than a cheap one. But fixed
resistors will better them both.

--
*There are 3 kinds of people: those who can count & those who can't.

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

There are only two ways to skin a rabbit....
 

"Dave Plowman (News)" wrote in message
...
In article ,
Keith G wrote:
I didn't 'leave it slamming'! I have no way of attenuating the signal
'til I get the Alps and fix my 'pot in a box' - is what my whole
previous thread was about!!

Make an attenuator out of fixed resistors. Only reason to go for a posh
pot is the channel balance is likely better than a cheap one. But fixed
resistors will better them both.


I did consider that and probably have already got some suitable/unused
resistors here, but dismissed it - certainly for long-term use - due to all
the variables. But you've given me the idea for an interesting little
fabrication - if I built a box with rows of 'in and out' phono sockets
connected to a number of fixed resistances, what values would you suggest?

There are only two ways to skin a rabbit....
 

On Tue, 20 Oct 2009 19:32:41 +0100, "Keith G"
wrote:


"Dave Plowman (News)" wrote in message
...
In article ,
Keith G wrote:
I didn't 'leave it slamming'! I have no way of attenuating the signal
'til I get the Alps and fix my 'pot in a box' - is what my whole
previous thread was about!!

Make an attenuator out of fixed resistors. Only reason to go for a posh
pot is the channel balance is likely better than a cheap one. But fixed
resistors will better them both.


I did consider that and probably have already got some suitable/unused
resistors here, but dismissed it - certainly for long-term use - due to all
the variables. But you've given me the idea for an interesting little
fabrication - if I built a box with rows of 'in and out' phono sockets
connected to a number of fixed resistances, what values would you suggest?


I reckon steps of 6dB (halving the voltage each time) would be about
right. You need a resistor in series (R1) followed by another to
ground (R2). By keeping the sum of them at about 10k, you will get
the best performance.

Att. R1 R2
6dB 5.1k 5.1k
12dB 8.2k 2.7k
18dB 8.2k 1.2k
24dB 8.9k 620 ohms

Not exact values, but the nearest that give standard resistors.

d

There are only two ways to skin a rabbit....
 

In message , Don Pearce
writes
On Tue, 20 Oct 2009 19:32:41 +0100, "Keith G"
wrote:


"Dave Plowman (News)" wrote in message
...
In article ,
Keith G wrote:
I didn't 'leave it slamming'! I have no way of attenuating the signal
'til I get the Alps and fix my 'pot in a box' - is what my whole
previous thread was about!!

Make an attenuator out of fixed resistors. Only reason to go for a posh
pot is the channel balance is likely better than a cheap one. But fixed
resistors will better them both.


I did consider that and probably have already got some suitable/unused
resistors here, but dismissed it - certainly for long-term use - due to all
the variables. But you've given me the idea for an interesting little
fabrication - if I built a box with rows of 'in and out' phono sockets
connected to a number of fixed resistances, what values would you suggest?


I reckon steps of 6dB (halving the voltage each time) would be about
right. You need a resistor in series (R1) followed by another to
ground (R2). By keeping the sum of them at about 10k, you will get
the best performance.

Att. R1 R2
6dB 5.1k 5.1k
12dB 8.2k 2.7k
18dB 8.2k 1.2k
24dB 8.9k 620 ohms

Not exact values, but the nearest that give standard resistors.

Those are the values for insertion between a zero impedance source and
an infinite impedance load. If your impedances are different, won't the
attenuation also differ?
--
Ian

There are only two ways to skin a rabbit....
 

On Wed, 21 Oct 2009 13:03:07 +0100, Ian Jackson
wrote:

In message , Don Pearce
writes
On Tue, 20 Oct 2009 19:32:41 +0100, "Keith G"
wrote:


"Dave Plowman (News)" wrote in message
...
In article ,
Keith G wrote:
I didn't 'leave it slamming'! I have no way of attenuating the signal
'til I get the Alps and fix my 'pot in a box' - is what my whole
previous thread was about!!

Make an attenuator out of fixed resistors. Only reason to go for a posh
pot is the channel balance is likely better than a cheap one. But fixed
resistors will better them both.


I did consider that and probably have already got some suitable/unused
resistors here, but dismissed it - certainly for long-term use - due to all
the variables. But you've given me the idea for an interesting little
fabrication - if I built a box with rows of 'in and out' phono sockets
connected to a number of fixed resistances, what values would you suggest?


I reckon steps of 6dB (halving the voltage each time) would be about
right. You need a resistor in series (R1) followed by another to
ground (R2). By keeping the sum of them at about 10k, you will get
the best performance.

Att. R1 R2
6dB 5.1k 5.1k
12dB 8.2k 2.7k
18dB 8.2k 1.2k
24dB 8.9k 620 ohms

Not exact values, but the nearest that give standard resistors.

Those are the values for insertion between a zero impedance source and
an infinite impedance load. If your impedances are different, won't the
attenuation also differ?

This isn't for measurements, just a useful stepped attenuator between
a notionally low and high impedance. The values won't be dead right,
but near enough for government work. The choice of 10k as a working
impedance is a reasonable loading compromise between typical input and
output impedances.

d

There are only two ways to skin a rabbit....
 

"Don Pearce" wrote in message

On Wed, 21 Oct 2009 13:03:07 +0100, Ian Jackson
wrote:

In message
, Don
Pearce writes
On Tue, 20 Oct 2009 19:32:41 +0100, "Keith G"
wrote:


"Dave Plowman (News)" wrote in
message ...
In article ,
Keith G wrote:
I didn't 'leave it slamming'! I have no way of
attenuating the signal 'til I get the Alps and fix
my 'pot in a box' - is what my whole previous thread
was about!!

Make an attenuator out of fixed resistors. Only
reason to go for a posh pot is the channel balance is
likely better than a cheap one. But fixed resistors
will better them both.


I did consider that and probably have already got some
suitable/unused resistors here, but dismissed it -
certainly for long-term use - due to all the
variables. But you've given me the idea for an
interesting little fabrication - if I built a box with
rows of 'in and out' phono sockets connected to a
number of fixed resistances, what values would you
suggest?


I reckon steps of 6dB (halving the voltage each time)
would be about right. You need a resistor in series
(R1) followed by another to ground (R2). By keeping the
sum of them at about 10k, you will get the best
performance.

Att. R1 R2
6dB 5.1k 5.1k
12dB 8.2k 2.7k
18dB 8.2k 1.2k
24dB 8.9k 620 ohms

Not exact values, but the nearest that give standard
resistors.

Those are the values for insertion between a zero
impedance source and an infinite impedance load. If your
impedances are different, won't the attenuation also
differ?

Of course, but we're not engineering the input attenuator for a Fluke 4 or 5
digit meter.

This isn't for measurements, just a useful stepped
attenuator between a notionally low and high impedance.
The values won't be dead right, but near enough for
government work. The choice of 10k as a working impedance
is a reasonable loading compromise between typical input
and output impedances.

Agreed, and consistent with accepted professional practice for recording.

There are only two ways to skin a rabbit....
 

Those are the values for insertion between a zero
impedance source and an infinite impedance load. If your
impedances are different, won't the attenuation also
differ?

Of course, but we're not engineering the input attenuator for a Fluke 4 or
5 digit meter.

This isn't for measurements, just a useful stepped
attenuator between a notionally low and high impedance.
The values won't be dead right, but near enough for
government work. The choice of 10k as a working impedance
is a reasonable loading compromise between typical input
and output impedances.

Agreed, and consistent with accepted professional practice for recording.


If you use three resistor in a Pi Attenuator arrangement you can set the
input and output impedances as well as attenuation (though of course the
laws of physics apply so you can't whatever you want).

http://chemandy.com/calculators/matc...calculator.htm

Is a handy online calc to determine values.