Equaliser for Shure V15III
 

I'm trying to improve the frequency response of my V15III/SME 3009 S2, and
remember that Shure or SME had a little equaliser circuit that flattened the
response at the expense of a couple of dBs of output. Something may have
been published in HFN and/or Wireless World in the '70s, but my HFNs don't
go back that far, and I can't find it in my WWs of the era.

I've been searching on-line for the circuit all afternoon, and can't find
anything. It was simply a capacitor and a resistor or two, but I can't
remember the configuration or values.

Does anyone have this info please?

Thanks

S.


--
http://audiopages.googlepages.com

Equaliser for Shure V15III
 

"Serge Auckland" wrote in message
...
I'm trying to improve the frequency response of my V15III/SME 3009 S2,
and remember that Shure or SME had a little equaliser circuit that
flattened the response at the expense of a couple of dBs of output.
Something may have been published in HFN and/or Wireless World in the
'70s, but my HFNs don't go back that far, and I can't find it in my
WWs of the era.

I've been searching on-line for the circuit all afternoon, and can't
find anything. It was simply a capacitor and a resistor or two, but I
can't remember the configuration or values.

Does anyone have this info please?

Thanks

S.


--
http://audiopages.googlepages.com


Ah, now this is one I do know about - it applied more or less across the
Shure range.

Shure cartridges were designed to work into a load of 47K resistance
(like all others) in parallel with something around 360pF capacitance.
The pickup arm cables and the interconnect to the amp would account for
about 120-150pF, which leaves the cartridge underloaded and thus rather
peaky and bright.

The answer - provided you have the skills to do it - is to make up two
short phono plug-socket link cables perhaps 3-4in long and fit a 220pF
capacitor inside one of the connectors in each cable. A small ceramic
capacitor of that sort of value should be no more than about 4mm square
and will fit quite easily. Remember capacitors are additive in value
when they are connected in parallel.

Total cost with components from Maplins would be about £5. There used to
be manufactured units that did the same thing and cost about £30
apiece - much the same thing with mains spike protectors which cost
about £5 to make (retail) and sell for £100++, especially those from
rip-off Russ. You may have to dig a bit to find the capacitors though.


--
Woody

harrogate three at ntlworld dot com

Equaliser for Shure V15III
 

Woody wrote:
"Serge Auckland" wrote in message
...
I'm trying to improve the frequency response of my V15III/SME 3009 S2,
and remember that Shure or SME had a little equaliser circuit that
flattened the response at the expense of a couple of dBs of output.
Something may have been published in HFN and/or Wireless World in the
'70s, but my HFNs don't go back that far, and I can't find it in my
WWs of the era.

I've been searching on-line for the circuit all afternoon, and can't
find anything. It was simply a capacitor and a resistor or two, but I
can't remember the configuration or values.

Does anyone have this info please?

Thanks

S.


--
http://audiopages.googlepages.com


Ah, now this is one I do know about - it applied more or less across the
Shure range.

Shure cartridges were designed to work into a load of 47K resistance
(like all others) in parallel with something around 360pF capacitance.
The pickup arm cables and the interconnect to the amp would account for
about 120-150pF, which leaves the cartridge underloaded and thus rather
peaky and bright.


The way the impedances work out, you get more peakiness as the load goes
up, not down. Adding an extra 200pF to the basic cartridge and wires
will increase the level at 10kHz by about 2.5dB. This is all about the
way the capacitance resonates with the inductance of the cartridge.

d

Equaliser for Shure V15III
 

"Don Pearce" wrote in message
...
Woody wrote:
"Serge Auckland" wrote in message
...
I'm trying to improve the frequency response of my V15III/SME 3009
S2, and remember that Shure or SME had a little equaliser circuit
that flattened the response at the expense of a couple of dBs of
output. Something may have been published in HFN and/or Wireless
World in the '70s, but my HFNs don't go back that far, and I can't
find it in my WWs of the era.

I've been searching on-line for the circuit all afternoon, and can't
find anything. It was simply a capacitor and a resistor or two, but
I can't remember the configuration or values.

Does anyone have this info please?

Thanks

S.


--
http://audiopages.googlepages.com


Ah, now this is one I do know about - it applied more or less across
the Shure range.

Shure cartridges were designed to work into a load of 47K resistance
(like all others) in parallel with something around 360pF
capacitance. The pickup arm cables and the interconnect to the amp
would account for about 120-150pF, which leaves the cartridge
underloaded and thus rather peaky and bright.


The way the impedances work out, you get more peakiness as the load
goes up, not down. Adding an extra 200pF to the basic cartridge and
wires will increase the level at 10kHz by about 2.5dB. This is all
about the way the capacitance resonates with the inductance of the
cartridge.

d


Try it - it's cheap and simple enough. I used a 75EDII with this process
and it tamed it well.

Maybe one of those occassions where the theory and practice don't match?


--
Woody

harrogate three at ntlworld dot com

Equaliser for Shure V15III
 

"Woody" wrote in message
...

Maybe one of those occassions where the theory and practice don't match?


Theory and practice always match, if it appears otherwise then you've
misunderstood the theory or there's some other factors involved that you
weren't aware of. The use of shunt capacitors acroos the replay heads of
analogue tape machines to boost the HF response was standard practice, often
these capacitors were switched according to the speed selected with larger
capacitor values being used on the lower speeds.

David.

Equaliser for Shure V15III
 

"David Looser" wrote in message
...
"Woody" wrote in message
...

Maybe one of those occassions where the theory and practice don't match?


Theory and practice always match, if it appears otherwise then you've
misunderstood the theory or there's some other factors involved that you
weren't aware of. The use of shunt capacitors acroos the replay heads of
analogue tape machines to boost the HF response was standard practice,
often these capacitors were switched according to the speed selected with
larger capacitor values being used on the lower speeds.

David.


The cartridge is rather dull, not bright, and I know about the recommended
capacitative load, but that's not what I'm after. In the mid '70s, somebody,
and I think it was either Shure themselves, or possibly SME, published a
cartridge equaliser circuit which consisted of one or two resistors and a
capacitor, may have been two caps, and which had the effect of lifting the
lower treble suck-out, and the extreme hf droop. It also had the effect of
dropping the total output by a couple of dB as I recall. It's that circuit
I'm looking for and sadly can't find.

You can see the frequency response I'm getting
http://audiopages.googlepages.com/V1...full;init:.png

My other cartridges, using the same test LP are fine. As an example, my EMT
cartridge does this:-

http://audiopages.googlepages.com/TS...full;init:.png

S.

--
http://audiopages.googlepages.com

Equaliser for Shure V15III
 

Woody wrote:

"Serge Auckland" wrote in message

I'm trying to improve the frequency response of my V15III/SME 3009 S2,
and remember that Shure or SME had a little equaliser circuit that
flattened the response at the expense of a couple of dBs of output.
Something may have been published in HFN and/or Wireless World in the
'70s, but my HFNs don't go back that far, and I can't find it in my
WWs of the era.

I've been searching on-line for the circuit all afternoon, and can't
find anything. It was simply a capacitor and a resistor or two, but I
can't remember the configuration or values.

Does anyone have this info please?

Ah, now this is one I do know about - it applied more or less across the
Shure range.

Shure cartridges were designed to work into a load of 47K resistance
(like all others) in parallel with something around 360pF capacitance.
The pickup arm cables and the interconnect to the amp would account for
about 120-150pF, which leaves the cartridge underloaded and thus rather
peaky and bright.

The answer - provided you have the skills to do it - is to make up two
short phono plug-socket link cables perhaps 3-4in long and fit a 220pF
capacitor inside one of the connectors in each cable. A small ceramic
capacitor of that sort of value should be no more than about 4mm square
and will fit quite easily. Remember capacitors are additive in value
when they are connected in parallel.

Total cost with components from Maplins would be about £5. There used to
be manufactured units that did the same thing and cost about £30
apiece - much the same thing with mains spike protectors which cost
about £5 to make (retail) and sell for £100++, especially those from
rip-off Russ. You may have to dig a bit to find the capacitors though.

Maplin does have capacitors but its website is so completely borked that a
search for 220pf brought up all sorts of values such as anything from 100pF
to 47nF !

One of the worst websites I've ever seen !

Graham

Equaliser for Shure V15III
 

"Don Pearce"
Woody wrote:

Shure cartridges were designed to work into a load of 47K resistance
(like all others) in parallel with something around 360pF capacitance.
The pickup arm cables and the interconnect to the amp would account for
about 120-150pF, which leaves the cartridge underloaded and thus rather
peaky and bright.


The way the impedances work out, you get more peakiness as the load goes
up, not down.


** Shure V15IIIs definitely sound brighter with less loading capacitance -
and or an increase in the load resistance above 47 kohms.


Adding an extra 200pF to the basic cartridge and wires will increase the
level at 10kHz by about 2.5dB.


** Don just plucked that figure out of his bum.

The real number is about 0.5dB at 8 to 10 kHz.

So barely audible.

What an extra 200pF * DOES * do is drop the response at 14 - 17 kHz by 3
or 4 dB - and THAT is what a person with good hearing notices as "
duller ".


This is all about the way the capacitance resonates with the inductance of
the cartridge.


** For anyone who cares to simulate the situation, a V15III has the
following :

L = 550 mH.

R = 1370 ohms

Fo = 42kHz ( equates to about 25 pF internal C )



...... Phil

Equaliser for Shure V15III
 

Serge Auckland wrote:

"David Looser" wrote in message
...
"Woody" wrote in message
...

Maybe one of those occassions where the theory and practice don't match?


Theory and practice always match, if it appears otherwise then you've
misunderstood the theory or there's some other factors involved that
you weren't aware of. The use of shunt capacitors acroos the replay
heads of analogue tape machines to boost the HF response was standard
practice, often these capacitors were switched according to the speed
selected with larger capacitor values being used on the lower speeds.

David.


The cartridge is rather dull, not bright, and I know about the
recommended capacitative load, but that's not what I'm after. In the mid
'70s, somebody, and I think it was either Shure themselves, or possibly
SME, published a cartridge equaliser circuit which consisted of one or
two resistors and a capacitor, may have been two caps, and which had the
effect of lifting the lower treble suck-out, and the extreme hf droop.
It also had the effect of dropping the total output by a couple of dB as
I recall. It's that circuit I'm looking for and sadly can't find.

You can see the frequency response I'm getting
http://audiopages.googlepages.com/V1...full;init:.png


My other cartridges, using the same test LP are fine. As an example, my
EMT cartridge does this:-

http://audiopages.googlepages.com/TS...full;init:.png


S.


Something a little odd there because the Shure appears to have an HF
droop of more like 10dB, and using just passive components you need to
lose that much to flatten things out. The response error looks like it
can be easily corrected with a very slight tweak of a standard treble
tone control; do you have one on your amplifier?

d

Equaliser for Shure V15III
 

Phil Allison wrote:
"Don Pearce"
Woody wrote:

Shure cartridges were designed to work into a load of 47K resistance
(like all others) in parallel with something around 360pF capacitance.
The pickup arm cables and the interconnect to the amp would account for
about 120-150pF, which leaves the cartridge underloaded and thus rather
peaky and bright.

The way the impedances work out, you get more peakiness as the load goes
up, not down.


** Shure V15IIIs definitely sound brighter with less loading capacitance -
and or an increase in the load resistance above 47 kohms.


Adding an extra 200pF to the basic cartridge and wires will increase the
level at 10kHz by about 2.5dB.


** Don just plucked that figure out of his bum.

The real number is about 0.5dB at 8 to 10 kHz.

So barely audible.

What an extra 200pF * DOES * do is drop the response at 14 - 17 kHz by 3
or 4 dB - and THAT is what a person with good hearing notices as "
duller ".


This is all about the way the capacitance resonates with the inductance of
the cartridge.


** For anyone who cares to simulate the situation, a V15III has the
following :

L = 550 mH.

R = 1370 ohms

Fo = 42kHz ( equates to about 25 pF internal C )



..... Phil







I did the simulation two years ago and the results are still he

http://81.174.169.10/odds/v15iii/cartridge.html

For some reason this page doesn't work well in IE (saved as HTML from
Mathcad), but use Firefox and it'll be fine. It shows how peaky the cart
gets with added capacitance. And of course a 3dB peak at 10kHz is going
to beat flat extension to 20kHz any day when it comes to sounding bright.

d