I'm using a Luxman C-1010 preamp with a variety of
Stanton/Pickering phono cartridges. The capacitance load
requirement for all of these cartridges is 275 pf. Luxman didn't
specify the capacitance of their input circuit. That's what I
need to know.

I have a capacitor test meter, so I can measure the capacitance
of all cabling; the meter goes bonkers on input circuits. I need
to come up with a quick and dirty way to determine the
capacitance of the preamp (or an actual figure!). I'd appreciate
any help, especially help that's accurate.

Thanks.

Richard

"Richard Steinfeld" wrote in message
...
I'm using a Luxman C-1010 preamp with a variety of
Stanton/Pickering phono cartridges. The capacitance load
requirement for all of these cartridges is 275 pf. Luxman didn't
specify the capacitance of their input circuit. That's what I
need to know.

I have a capacitor test meter, so I can measure the capacitance
of all cabling; the meter goes bonkers on input circuits. I need
to come up with a quick and dirty way to determine the
capacitance of the preamp (or an actual figure!). I'd appreciate
any help, especially help that's accurate.

You're going about it the wrong way. The 275pF figure may not be exact for
your cartridge anyway, so an accurate measurement may make you feel good,
but not necessarily give you flattest response..
Get a good test record and adjust the input capacitance for flattest high
frequency response.

TonyP.

"Richard Steinfeld" wrote in message
...
I'm using a Luxman C-1010 preamp with a variety of
Stanton/Pickering phono cartridges. The capacitance load
requirement for all of these cartridges is 275 pf. Luxman didn't
specify the capacitance of their input circuit. That's what I
need to know.

I have a capacitor test meter, so I can measure the capacitance
of all cabling; the meter goes bonkers on input circuits. I need
to come up with a quick and dirty way to determine the
capacitance of the preamp (or an actual figure!). I'd appreciate
any help, especially help that's accurate.

You're going about it the wrong way. The 275pF figure may not be exact for
your cartridge anyway, so an accurate measurement may make you feel good,
but not necessarily give you flattest response..
Get a good test record and adjust the input capacitance for flattest high
frequency response.

TonyP.

"Richard Steinfeld" wrote in message
...
I'm using a Luxman C-1010 preamp with a variety of
Stanton/Pickering phono cartridges. The capacitance load
requirement for all of these cartridges is 275 pf. Luxman didn't
specify the capacitance of their input circuit. That's what I
need to know.

I have a capacitor test meter, so I can measure the capacitance
of all cabling; the meter goes bonkers on input circuits. I need
to come up with a quick and dirty way to determine the
capacitance of the preamp (or an actual figure!). I'd appreciate
any help, especially help that's accurate.

You're going about it the wrong way. The 275pF figure may not be exact for
your cartridge anyway, so an accurate measurement may make you feel good,
but not necessarily give you flattest response..
Get a good test record and adjust the input capacitance for flattest high
frequency response.

TonyP.

TonyP wrote:

"Richard Steinfeld" wrote in message
...

I'm using a Luxman C-1010 preamp with a variety of
Stanton/Pickering phono cartridges. The capacitance load
requirement for all of these cartridges is 275 pf. Luxman didn't
specify the capacitance of their input circuit. That's what I
need to know.

I have a capacitor test meter, so I can measure the capacitance
of all cabling; the meter goes bonkers on input circuits. I need
to come up with a quick and dirty way to determine the
capacitance of the preamp (or an actual figure!). I'd appreciate
any help, especially help that's accurate.


You're going about it the wrong way. The 275pF figure may not be exact for
your cartridge anyway, so an accurate measurement may make you feel good,
but not necessarily give you flattest response..
Get a good test record and adjust the input capacitance for flattest high
frequency response.

TonyP.


Flattest? Or closest to the RIAA curve? Where are you suggesting he
measure?

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form .

TonyP wrote:

"Richard Steinfeld" wrote in message
...

I'm using a Luxman C-1010 preamp with a variety of
Stanton/Pickering phono cartridges. The capacitance load
requirement for all of these cartridges is 275 pf. Luxman didn't
specify the capacitance of their input circuit. That's what I
need to know.

I have a capacitor test meter, so I can measure the capacitance
of all cabling; the meter goes bonkers on input circuits. I need
to come up with a quick and dirty way to determine the
capacitance of the preamp (or an actual figure!). I'd appreciate
any help, especially help that's accurate.


You're going about it the wrong way. The 275pF figure may not be exact for
your cartridge anyway, so an accurate measurement may make you feel good,
but not necessarily give you flattest response..
Get a good test record and adjust the input capacitance for flattest high
frequency response.

TonyP.


Flattest? Or closest to the RIAA curve? Where are you suggesting he
measure?

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form .

TonyP wrote:

"Richard Steinfeld" wrote in message
...

I'm using a Luxman C-1010 preamp with a variety of
Stanton/Pickering phono cartridges. The capacitance load
requirement for all of these cartridges is 275 pf. Luxman didn't
specify the capacitance of their input circuit. That's what I
need to know.

I have a capacitor test meter, so I can measure the capacitance
of all cabling; the meter goes bonkers on input circuits. I need
to come up with a quick and dirty way to determine the
capacitance of the preamp (or an actual figure!). I'd appreciate
any help, especially help that's accurate.


You're going about it the wrong way. The 275pF figure may not be exact for
your cartridge anyway, so an accurate measurement may make you feel good,
but not necessarily give you flattest response..
Get a good test record and adjust the input capacitance for flattest high
frequency response.

TonyP.


Flattest? Or closest to the RIAA curve? Where are you suggesting he
measure?

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form .

In , on 06/27/04
at 08:45 PM, "Richard Steinfeld"
said:

I'm using a Luxman C-1010 preamp with a variety of
Stanton/Pickering phono cartridges. The capacitance load
requirement for all of these cartridges is 275 pf. Luxman didn't
specify the capacitance of their input circuit. That's what I need to
know.

I have a capacitor test meter, so I can measure the capacitance of all
cabling; the meter goes bonkers on input circuits. I need to come up
with a quick and dirty way to determine the
capacitance of the preamp (or an actual figure!). I'd appreciate any
help, especially help that's accurate.

Generally, the electronic manufacturers expect cartridges need loading
in this range and design their inputs accordingly. (Unfortunately, they
must guess the turntable wiring capacitance.)

I assume that the C-1010's active components in the input circuit are
frustrating the capacitance meter. Try using the lowest test voltage
that you can. If you don't mind fussing with things, break the
connection between the input jack as physically close to the first
active device as you can.

There will probably be a difference between measuring while the C-1010
is turned on or off, but in general, I feel that the test voltage will
be a bit high and you'll bump into some nonlinearity either way.

There are many methods that could be used to measure capacitance. Pick
one that measures at less than 0.5 volts pp otherwise you could run
into an active component inside the preamp that turns on.

One method that you may be able to manage is to insert a known
capacitor in series with the tester. This may reduce the voltage enough
to avoid the nonlinearity in the preamp and block any DC component from
the tester.

Another technique would be to inject a known single frequency into the
preamp through a resistor and measure the voltage at the RCA jack. Then
start adding parallel capacitors until the voltage falls to 50 percent
of the original. Be careful to use a low signal voltage. Don't forget
to deal with the input capacitance of the voltage measuring device and
your tester.

---

Others have suggested measuring the frequency response of the system
using a test record and tune the result for a flat response. This
sounds like a good idea, but I think you will find enough variation in
different test records to frustrate your sense of accuracy. Also, be
very careful to duplicate the temperature during all test runs, then
operate your turntable at that temperature. Finally, cartridges,
typically, are not very flat. There are peaks, dips, and resonances.
You may have to scratch your head a bit to decide when things are
"flat".

As you measure the frequency response, keep the response of your
measuring device in mind. Most DVM's are not flat enough for audio
work.

---

I think your easiest path is to examine the preamp's input circuit. You
may find series and/or parallel capacitors in front of the first active
device. Calculate the equivalent capacitance of that network and add a
few pF for the wiring.

-----------------------------------------------------------
spam:
wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15
13 (Barry Mann)
[sorry about the puzzle, spammers are ruining my mailbox]
-----------------------------------------------------------

In , on 06/27/04
at 08:45 PM, "Richard Steinfeld"
said:

I'm using a Luxman C-1010 preamp with a variety of
Stanton/Pickering phono cartridges. The capacitance load
requirement for all of these cartridges is 275 pf. Luxman didn't
specify the capacitance of their input circuit. That's what I need to
know.

I have a capacitor test meter, so I can measure the capacitance of all
cabling; the meter goes bonkers on input circuits. I need to come up
with a quick and dirty way to determine the
capacitance of the preamp (or an actual figure!). I'd appreciate any
help, especially help that's accurate.

Generally, the electronic manufacturers expect cartridges need loading
in this range and design their inputs accordingly. (Unfortunately, they
must guess the turntable wiring capacitance.)

I assume that the C-1010's active components in the input circuit are
frustrating the capacitance meter. Try using the lowest test voltage
that you can. If you don't mind fussing with things, break the
connection between the input jack as physically close to the first
active device as you can.

There will probably be a difference between measuring while the C-1010
is turned on or off, but in general, I feel that the test voltage will
be a bit high and you'll bump into some nonlinearity either way.

There are many methods that could be used to measure capacitance. Pick
one that measures at less than 0.5 volts pp otherwise you could run
into an active component inside the preamp that turns on.

One method that you may be able to manage is to insert a known
capacitor in series with the tester. This may reduce the voltage enough
to avoid the nonlinearity in the preamp and block any DC component from
the tester.

Another technique would be to inject a known single frequency into the
preamp through a resistor and measure the voltage at the RCA jack. Then
start adding parallel capacitors until the voltage falls to 50 percent
of the original. Be careful to use a low signal voltage. Don't forget
to deal with the input capacitance of the voltage measuring device and
your tester.

---

Others have suggested measuring the frequency response of the system
using a test record and tune the result for a flat response. This
sounds like a good idea, but I think you will find enough variation in
different test records to frustrate your sense of accuracy. Also, be
very careful to duplicate the temperature during all test runs, then
operate your turntable at that temperature. Finally, cartridges,
typically, are not very flat. There are peaks, dips, and resonances.
You may have to scratch your head a bit to decide when things are
"flat".

As you measure the frequency response, keep the response of your
measuring device in mind. Most DVM's are not flat enough for audio
work.

---

I think your easiest path is to examine the preamp's input circuit. You
may find series and/or parallel capacitors in front of the first active
device. Calculate the equivalent capacitance of that network and add a
few pF for the wiring.

-----------------------------------------------------------
spam:
wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15
13 (Barry Mann)
[sorry about the puzzle, spammers are ruining my mailbox]
-----------------------------------------------------------

In , on 06/27/04
at 08:45 PM, "Richard Steinfeld"
said:

I'm using a Luxman C-1010 preamp with a variety of
Stanton/Pickering phono cartridges. The capacitance load
requirement for all of these cartridges is 275 pf. Luxman didn't
specify the capacitance of their input circuit. That's what I need to
know.

I have a capacitor test meter, so I can measure the capacitance of all
cabling; the meter goes bonkers on input circuits. I need to come up
with a quick and dirty way to determine the
capacitance of the preamp (or an actual figure!). I'd appreciate any
help, especially help that's accurate.

Generally, the electronic manufacturers expect cartridges need loading
in this range and design their inputs accordingly. (Unfortunately, they
must guess the turntable wiring capacitance.)

I assume that the C-1010's active components in the input circuit are
frustrating the capacitance meter. Try using the lowest test voltage
that you can. If you don't mind fussing with things, break the
connection between the input jack as physically close to the first
active device as you can.

There will probably be a difference between measuring while the C-1010
is turned on or off, but in general, I feel that the test voltage will
be a bit high and you'll bump into some nonlinearity either way.

There are many methods that could be used to measure capacitance. Pick
one that measures at less than 0.5 volts pp otherwise you could run
into an active component inside the preamp that turns on.

One method that you may be able to manage is to insert a known
capacitor in series with the tester. This may reduce the voltage enough
to avoid the nonlinearity in the preamp and block any DC component from
the tester.

Another technique would be to inject a known single frequency into the
preamp through a resistor and measure the voltage at the RCA jack. Then
start adding parallel capacitors until the voltage falls to 50 percent
of the original. Be careful to use a low signal voltage. Don't forget
to deal with the input capacitance of the voltage measuring device and
your tester.

---

Others have suggested measuring the frequency response of the system
using a test record and tune the result for a flat response. This
sounds like a good idea, but I think you will find enough variation in
different test records to frustrate your sense of accuracy. Also, be
very careful to duplicate the temperature during all test runs, then
operate your turntable at that temperature. Finally, cartridges,
typically, are not very flat. There are peaks, dips, and resonances.
You may have to scratch your head a bit to decide when things are
"flat".

As you measure the frequency response, keep the response of your
measuring device in mind. Most DVM's are not flat enough for audio
work.

---

I think your easiest path is to examine the preamp's input circuit. You
may find series and/or parallel capacitors in front of the first active
device. Calculate the equivalent capacitance of that network and add a
few pF for the wiring.

-----------------------------------------------------------
spam:
wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15
13 (Barry Mann)
[sorry about the puzzle, spammers are ruining my mailbox]
-----------------------------------------------------------

"CJT" wrote in message


TonyP wrote:
You're going about it the wrong way. The 275pF figure may not be
exact for your cartridge anyway, so an accurate measurement may make
you feel good, but not necessarily give you flattest response..
Get a good test record and adjust the input capacitance for flattest
high frequency response.

Agreed.

Flattest? Or closest to the RIAA curve? Where are you suggesting he
measure?

Test records are generally made with RIAA pre-emphais, so your goal is
flattest possible response via the output of a RIAA equalized preamp.

The High Fidelity News test record is arguably the best contemporary test
record. However, many audiophiles bought test records in the past and never
seriously used them. So, there are quite a number of the classic test
records of the past (example CBS labs and Stereo Review) in good shape,
available on eBay and the like.

"CJT" wrote in message


TonyP wrote:
You're going about it the wrong way. The 275pF figure may not be
exact for your cartridge anyway, so an accurate measurement may make
you feel good, but not necessarily give you flattest response..
Get a good test record and adjust the input capacitance for flattest
high frequency response.

Agreed.

Flattest? Or closest to the RIAA curve? Where are you suggesting he
measure?

Test records are generally made with RIAA pre-emphais, so your goal is
flattest possible response via the output of a RIAA equalized preamp.

The High Fidelity News test record is arguably the best contemporary test
record. However, many audiophiles bought test records in the past and never
seriously used them. So, there are quite a number of the classic test
records of the past (example CBS labs and Stereo Review) in good shape,
available on eBay and the like.

"CJT" wrote in message


TonyP wrote:
You're going about it the wrong way. The 275pF figure may not be
exact for your cartridge anyway, so an accurate measurement may make
you feel good, but not necessarily give you flattest response..
Get a good test record and adjust the input capacitance for flattest
high frequency response.

Agreed.

Flattest? Or closest to the RIAA curve? Where are you suggesting he
measure?

Test records are generally made with RIAA pre-emphais, so your goal is
flattest possible response via the output of a RIAA equalized preamp.

The High Fidelity News test record is arguably the best contemporary test
record. However, many audiophiles bought test records in the past and never
seriously used them. So, there are quite a number of the classic test
records of the past (example CBS labs and Stereo Review) in good shape,
available on eBay and the like.

"Barry Mann" wrote in message
om


As you measure the frequency response, keep the response of your
measuring device in mind. Most DVM's are not flat enough for audio
work.

Agreed. DVM's tend to break down into two categories w/r/t frequency
response.

Many are basically designed for measuring power line voltages, and have
pretty fair response up to about 1 KHz. Their response then drops like a
stone.

Others are designed to have good frequency response. I have a Fluke 85, and
it is within 0.5 dB or better over the audio band. I have a Protek 506, and
its within about 0.5 dB up to 20 KHz.

Arguably, the best way to measure the frequency response of a vinyl playback
system is to use a good computer sound card. hooked to the output of your
phono preamp, or stand-alone component preamp. Record the playback of a test
record and then analyze it.

You can confirm the performance of your sound card using a freebie download
called "RightMark Audio Analyzer"

The frequency response range affected by capacitive loading is 500 Hz. You
can get more consistent measurements if you filter out noise and garbage
below 500 Hz, which some DAW software like CoolEdit and Goldwave support.
They also have analytical features that will enable you to make accurate
measurements of selections in a file.

"Barry Mann" wrote in message
om


As you measure the frequency response, keep the response of your
measuring device in mind. Most DVM's are not flat enough for audio
work.

Agreed. DVM's tend to break down into two categories w/r/t frequency
response.

Many are basically designed for measuring power line voltages, and have
pretty fair response up to about 1 KHz. Their response then drops like a
stone.

Others are designed to have good frequency response. I have a Fluke 85, and
it is within 0.5 dB or better over the audio band. I have a Protek 506, and
its within about 0.5 dB up to 20 KHz.

Arguably, the best way to measure the frequency response of a vinyl playback
system is to use a good computer sound card. hooked to the output of your
phono preamp, or stand-alone component preamp. Record the playback of a test
record and then analyze it.

You can confirm the performance of your sound card using a freebie download
called "RightMark Audio Analyzer"

The frequency response range affected by capacitive loading is 500 Hz. You
can get more consistent measurements if you filter out noise and garbage
below 500 Hz, which some DAW software like CoolEdit and Goldwave support.
They also have analytical features that will enable you to make accurate
measurements of selections in a file.

"Barry Mann" wrote in message
om


As you measure the frequency response, keep the response of your
measuring device in mind. Most DVM's are not flat enough for audio
work.

Agreed. DVM's tend to break down into two categories w/r/t frequency
response.

Many are basically designed for measuring power line voltages, and have
pretty fair response up to about 1 KHz. Their response then drops like a
stone.

Others are designed to have good frequency response. I have a Fluke 85, and
it is within 0.5 dB or better over the audio band. I have a Protek 506, and
its within about 0.5 dB up to 20 KHz.

Arguably, the best way to measure the frequency response of a vinyl playback
system is to use a good computer sound card. hooked to the output of your
phono preamp, or stand-alone component preamp. Record the playback of a test
record and then analyze it.

You can confirm the performance of your sound card using a freebie download
called "RightMark Audio Analyzer"

The frequency response range affected by capacitive loading is 500 Hz. You
can get more consistent measurements if you filter out noise and garbage
below 500 Hz, which some DAW software like CoolEdit and Goldwave support.
They also have analytical features that will enable you to make accurate
measurements of selections in a file.

"Barry Mann" wrote in message
om...
Others have suggested measuring the frequency response of the system
using a test record and tune the result for a flat response. This
sounds like a good idea, but I think you will find enough variation in
different test records to frustrate your sense of accuracy.

I think you will find most test records are better than anything else you
are likely to play on the turntable, so it hardly matters IMO.
Vinyl is simply not a high accuracy source to begin with. What you seem to
be saying is that the measurements should be much more accurate than the
records. Why? (other than feel good factor)

Also, be
very careful to duplicate the temperature during all test runs, then
operate your turntable at that temperature.

This is also a trifle obsessive, but sure, the measurements should be made
at 20 - 23degC.

Finally, cartridges,
typically, are not very flat. There are peaks, dips, and resonances.
You may have to scratch your head a bit to decide when things are
"flat".

A good cartridge will not have serious peaks dips or resonances in the
20-20kHz band. If it does, get a new one :-)
The two main resonaces should occur below 20Hz and above 20 kHz.

As you measure the frequency response, keep the response of your
measuring device in mind. Most DVM's are not flat enough for audio
work.

Usually the case, but easy to check.

TonyP.

"Barry Mann" wrote in message
om...
Others have suggested measuring the frequency response of the system
using a test record and tune the result for a flat response. This
sounds like a good idea, but I think you will find enough variation in
different test records to frustrate your sense of accuracy.

I think you will find most test records are better than anything else you
are likely to play on the turntable, so it hardly matters IMO.
Vinyl is simply not a high accuracy source to begin with. What you seem to
be saying is that the measurements should be much more accurate than the
records. Why? (other than feel good factor)

Also, be
very careful to duplicate the temperature during all test runs, then
operate your turntable at that temperature.

This is also a trifle obsessive, but sure, the measurements should be made
at 20 - 23degC.

Finally, cartridges,
typically, are not very flat. There are peaks, dips, and resonances.
You may have to scratch your head a bit to decide when things are
"flat".

A good cartridge will not have serious peaks dips or resonances in the
20-20kHz band. If it does, get a new one :-)
The two main resonaces should occur below 20Hz and above 20 kHz.

As you measure the frequency response, keep the response of your
measuring device in mind. Most DVM's are not flat enough for audio
work.

Usually the case, but easy to check.

TonyP.

"Barry Mann" wrote in message
om...
Others have suggested measuring the frequency response of the system
using a test record and tune the result for a flat response. This
sounds like a good idea, but I think you will find enough variation in
different test records to frustrate your sense of accuracy.

I think you will find most test records are better than anything else you
are likely to play on the turntable, so it hardly matters IMO.
Vinyl is simply not a high accuracy source to begin with. What you seem to
be saying is that the measurements should be much more accurate than the
records. Why? (other than feel good factor)

Also, be
very careful to duplicate the temperature during all test runs, then
operate your turntable at that temperature.

This is also a trifle obsessive, but sure, the measurements should be made
at 20 - 23degC.

Finally, cartridges,
typically, are not very flat. There are peaks, dips, and resonances.
You may have to scratch your head a bit to decide when things are
"flat".

A good cartridge will not have serious peaks dips or resonances in the
20-20kHz band. If it does, get a new one :-)
The two main resonaces should occur below 20Hz and above 20 kHz.

As you measure the frequency response, keep the response of your
measuring device in mind. Most DVM's are not flat enough for audio
work.

Usually the case, but easy to check.

TonyP.