Help needed with MC Cartridge Output...

[Vintagear]

A while back I tried a cartridge with a .33mV output and I felt that it had too much gain when paired with my MC stage. Based on my limited research I think the optimal MC cart for me should have an output of ~.15mV.

I'm also not sure how to calculate the gain of my MC stage. Below are the specs I have, can someone confirm this before I start to look for a cart with such a low output (they do not seem common).

Input Sensitivity & Impedance (at 1kHz)
MC - 0.1mV / 200 Ohms
MM - 2.5mV / 47k Ohms

SNR (short circuit A-network)
MC - 76 dB (-156dBV)
MM - 91 dB

Channel Separation (1kHz, at rated power)
MC - 70dB
MM - 75dB

Maximum Input Capability (at 1kHz 0.01% THD)
MC - 40mV RMS
MM - 330mV RMS


Let me know if there is any other info or spec needed to make the determination.

Thanks in advance.

 

[Muddywaters]

The max input for MC is listed as 40mV so the cart you tested @ .33mV should be fine.

Is it bothering you because you reach your volume settings at a lower range on your attenuator?

 

[rothwellaudio]

No, you can't determine the gain of the phonostage from those specs but quoting 0.1mV for sensitivity suggests to me that there's a lot of gain there, certainly more than 60dB, and unusually high.
If you let us know what the phonostage is, somebody might have the figures.

 

[Vintagear]

The max input for MC is listed as 40mV so the cart you tested @ .33mV should be fine.

Is it bothering you because you reach your volume settings at a lower range on your attenuator?

The .33mV hybrid cart did not sound optimal to me even if I bypassed the flat-amp to reduce the gain by -14dB. It just sounded overdriven to me.

No, you can't determine the gain of the phonostage from those specs but quoting 0.1mV for sensitivity suggests to me that there's a lot of gain there, certainly more than 60dB, and unusually high.
If you let us know what the phonostage is, somebody might have the figures.

Thank you, I was hoping someone knowledgeable like you might help with this. Yes, there is definitely a lot of gain in this MC stage. As for the MM stage I can say it's fantastic and very quiet but I'd really like to hear the potential of the MC stage.

The phono stages are in my integrated amp (the unit has been fully restored). You can read a little about it's design on pages 6 & 7 of the attached manual. A separate transformer feeds the phono stages. The pictures only show one channel of each stage and exclude the motherboard all four boards are attached to. In the picture on page 11 you can see the amount of real estate devoted to the phono stages in this amp (which is a large amp to start with), the motherboard is to the right in yellow with the 4 MM & MC boards attached to it. The picture is with all the shielding removed, if you look at my avatar you can see it to the right with the shield. It really is a beast of a phono stage.

https://www.vintageshifi.com/repertoire-pdf/pdf/telecharge.php?pdf=Sansui-AU-X1-Brochure.pdf

I want to be sure I look for the optimal MC cartridge. Any insight would be appreciated.

 

[Bob]

math wise it's 20 log v1/v2.

but are you sure you want only an MC cart that only just matches the gain?

I've had several MCs and they all sound different and they also vary in their tracking force,
resonant frequency and other things.

you may find a cart that matches the gain, but the sound stage is perfect for classical
orchestral works and not so good for rock. then there's the tracking of something
like the Telarc 1812 LP's cannon blasts at the finale.

all this assumes that your arm on your TT can accommodate both high and low
compliance carts - generally they don't (the only way is to get a super low mass arm
to run high compliance carts then add mass - custom made counterweights to support
some of the low compliance MC carts like from Denon)

at some point you run out of money or need to have a custom built cartridge from the
remaining MC designers. I'd look at the top of the lines for Ortofon and dynavector
but swallow coffee first - these might cost $10 per play.

 

[Vintagear]

math wise it's 20 log v1/v2.

but are you sure you want only an MC cart that only just matches the gain?

I've had several MCs and they all sound different and they also vary in their tracking force,
resonant frequency and other things.

you may find a cart that matches the gain, but the sound stage is perfect for classical
orchestral works and not so good for rock. then there's the tracking of something
like the Telarc 1812 LP's cannon blasts at the finale.

all this assumes that your arm on your TT can accommodate both high and low
compliance carts - generally they don't (the only way is to get a super low mass arm
to run high compliance carts then add mass - custom made counterweights to support
some of the low compliance MC carts like from Denon)

at some point you run out of money or need to have a custom built cartridge from the
remaining MC designers. I'd look at the top of the lines for Ortofon and dynavector
but swallow coffee first - these might cost $10 per play.

Yup, there are sooo many considerations and I'm not looking to go crazy but I figured I'd start with the gain first and then look for a compliance that would work with a medium mass arm. Just really wanted something to give it a fair listen (cartridge presentation preferences aside).

Then I'd try to find something lightly used on BT or another site.

 

[Bob]

in retrospect you'd want a MC pre-preamp stage that offers more gain to be able to
control the noise floor

I'd spend low bucks on the low end MC carts you might find lightly used - just to get
used to the sound and the operational/functional features (aka quirks)

low-end Benz (not the car) are good starters. for Olympic-class work, try buying
a broken dynavector Ruby or 10x series (spend little - its broken) and have it
refurbed (about a dozen different places) with choice of born/ruby cantilevers
and diamond tips with various shapes) - cost about $100.

and there's no stopping you with tweaking the external specs (loading) and internal
ones (inside the Sansui), nor using external phono amps with or without MC
stages. the SOTA has improved since the Sansui designs were finalized so
many years ago.

lastly, the music you listen to makes a big difference as well as the associated
equipment and these don't change as much as the electronics and the cart.

 

[Vintagear]

in retrospect you'd want a MC pre-preamp stage that offers more gain to be able to
control the noise floor

I'd spend low bucks on the low end MC carts you might find lightly used - just to get
used to the sound and the operational/functional features (aka quirks)

low-end Benz (not the car) are good starters. for Olympic-class work, try buying
a broken dynavector Ruby or 10x series (spend little - its broken) and have it
refurbed (about a dozen different places) with choice of born/ruby cantilevers
and diamond tips with various shapes) - cost about $100.

and there's no stopping you with tweaking the external specs (loading) and internal
ones (inside the Sansui), nor using external phono amps with or without MC
stages. the SOTA has improved since the Sansui designs were finalized so
many years ago.

lastly, the music you listen to makes a big difference as well as the associated
equipment and these don't change as much as the electronics and the cart.

I took a look at the formula you posted and it seems to tell me the gain needed to get a specific output.

So for example, to get 0.1mV from a .15mV cart you need 56.4db of gain (if I did the math correctly) and for the .33mv cart I would need 30.2dB of gain but it doesn't tell me how much gain my MC stage has, or does it? This seems to line up with my hunch that my MC stage has a lot of gain because it did not sound right with the .33mV cart. So I think I'm on the right track.

Believe me, this MM/MC stage if very quiet. I'd just like to know how to determine the actual gain that it has to be sure I match it with a proper cartridge.

How can I confirm this?

EDIT: I just tried the KAB calculator (not sure if I'm using it right) but it calculates a gain of 68dB for my MC stage output of .1mV (which is in-line with the @rothwellaudio estimate of >60dB in post #3). If I then enter to compute the optimal gain for a .15mV cart it calculates 67dB.

https://www.kabusa.com/pregain.htm

Am I doing this correctly? Is it possible that my MC head amp has a high gain of 68dB ? I assume the fact that it's transformer based with 24 FETS and not op amps make a difference in SQ too?

Can someone please confirm that a ~.15mV cart would be the best match for the listed specs of my MC stage?

 

[Bob]

the MC stage is usually specified by itself and the total gain is calculated by adding
the MM or phonostage gain. Transformers don't have gain in this particular sense
since, in this particular use case, it does not amplify so that the traditional use
of db gain does not apply in this situation.

I am caveating everything here just in case the TCKs come and dump S**T
with specious comments and counterfactual arguments.

for transformer-based MC stages it's a voltage multiplier, .xx mv to x mv that is
in an OK range suitable for the MM phono stage that follows.

68db, if that's correct, is in the normal range for MC gain amplification. it is neither
high nor low - merely in range.

it is not the components (FETs, opamps, tubes, etc) that makes a difference in SQ.
there are great examples of opamp MC/MM phonostages like APT Holman, tube
Audio Research, etc. there are great tube preamps with FETs. and my favorites
are non-FET Haflers, and in second place opamp Haflers.

it is the design using whatever components the designer is comfortable with. and
often less to do with bean counters and costs - Japanese vendors tend to create
house sounds so their products have similar SQ and one way they do this is use
carbon film resistors which are generally cheaper than the boutique metal films.
but some will say these CF resistors are due to bean counters.

no one will go out on a limb and say the only possible and optimal match is .15mv
with 68db. you would be overwhelmed by the SQ differences compared to a .16mv
and 67db gain way before you could possibly hear the voltage differences between the two.

you should be aware that the specified gain for both cartridge and the MC and
the MM stages (3) are all based on ONE specific testing frequency - usually 1Khz.
and unless you listen to test tones you may find that the total gain of all
three vary across the normal LP frequency range. and you will notice the
SQ and not any artifacts with "optimal" gain matching.

suppose no one answers your question - are you willing spend, say 10K for
a custom build of a cartridge to yield this questionable .15mv at some
frequency and to find some LP that plays back with this custom cartridge
at EXACTLY 0.15mv?

next, what if your Sansui gets damaged and you move to a different Sansui model
or even a HK, Yamaha, Pioneer, high-end units and find out their MC gain is 65db.

and don't know if you know this but there are FET (as well as bipolar) opamps
and you can with simple 2 resistor changes (per channel) change the gain from original
to 68 or 68.5 or 67.5 or 70db.

so if the MC cart you can afford yields some number higher or lower MV
would you be able to hear the difference.

I've had well over a dozen different carts on a low mass arm and any differences
in voltage is very simply changed with minor volume control tweaks.

I think there's no perfect theoretical answer until you find and name that
.15mv cart. there may not be a cart out there.

 

[rothwellaudio]

I took a look at the formula you posted and it seems to tell me the gain needed to get a specific output.
So for example, to get 0.1mV from a .15mV cart you need 56.4db of gain (if I did the math correctly)

To get 0.1mV from a 0.15mV cartridge you would have to attenuate the signal. I think you meant 0.1V, not 0.1mV. But what was your reason for choosing 0.1V as your target figure?

...but it doesn't tell me how much gain my MC stage has, or does it?

No, it doesn't - but does it really matter?

I assume the fact that it's transformer based with 24 FETS and not op amps make a difference in SQ too?

I think you have misunderstood - this is not a transformer-based MC stage with step-up transformers for the audio signal, it is a discreet FET/bipolar transistor design. The mention of transformers in the manual refers to separate windings on the mains transformer to feed the power supply for the phono section.
Actually, it's a very comprehensive manual/brochure with lots of detail and much more impressive than a lot of the modern stuff. The phono section has a moving magnet preamp with an unspecified amount of gain but a quoted input sensitivity (for an unquoted output) of 2.5mV. That's pretty normal. The moving magnet preamp is preceded by pre-preamp to handle moving coil cartridges. This pre-preamp has a gain of 28dB and gives the MC input a quoted sensitivity of 0.1mV. That means a cartridge with an output of 0.1mV will drive the phono section to its nominal output level, whatever that is. A cartridge with a higher output will drive the phono section to a higher output level, but that shouldn't matter because you would need an mc cartridge with an output of 40mV to overdrive the phono section. That gives the phono section 52dB of headroom over its nominal input sensitivity.

Really, it seems to me that you're over-thinking all this. The amp's quoted input sensitivity for mc cartridges is 0.1mV, so that's the "ideal" cartridge output for this amp. A cartridge with an output of 0.33mV would give you a bit more volume, but it's only 10dB more than 0.1mV and you still have 40dB of headroom left before you overload the phono section, so it's all good.

A while back I tried a cartridge with a .33mV output and I felt that it had too much gain when paired with my MC stage.

Maybe that's what you "felt", but cartridges don't have gain, they have output voltages. Amplifiers have gain.
If you didn't like the sound of the cartridge it's probably due to any number of other factors, not an issue with too much gain.

 

[bimasta]

It's an impressive amp (I almost bought one and wish I had) and I sense it has pride of place in your system. But it may not be the cartridge(s) you've tried, it may be you just don't like the MC stage.

 

[rothwellaudio]

It's an impressive amp (I almost bought one and wish I had) and I sense it has pride of place in your system.

Yes, this appears to be from a time when audio engineers were competing to get the best out of phonostages and amplifiers in general, and the market for this kind of stuff was big enough to interest large-scale manufacturers with considerable R&D budgets. The number of FETs paralleled-up in the pre-preamp to reduce noise is quite impressive.

 

[bimasta]

Yes, this appears to be from a time when audio engineers were competing to get the best out of phonostages and amplifiers in general, and the market for this kind of stuff was big enough to interest large-scale manufacturers with considerable R&D budgets. The number of FETs paralleled-up in the pre-preamp to reduce noise is quite impressive.

It was made in the early '80s, before CD's blitzkrieg, and Vinyl still ruled, the main source in every system. Before it became an 'optional extra' or eliminated entirely. I have a Denon receiver, TOTL at the time, and it too has a fine phono stage, with both MM and MC.

Sometimes I use it in place of my separates, but keeping my best carts/arm/TT and speakers — I hear slight loss in SQ, but not satisfaction. And some less audiophiliac friends prefer it: a bit less detail may give them a more 'holistic' presentation. And the Tuner is very good. Sometimes the convenience of an all-in-one component, needing so little space and without a jungle of cables, outweighs the quest for "the absolute sound."

A disadvantage of such designs is they often share a power supply with a great honking power amp, so loud passages or dynamic transients can disrupt the subtler needs of the phono section. But the new species of stand-alone units often use a basic wall-wart, also a limiting factor. Today's temptingly affordable standalone phono preamps may require an equal extra expenditure to reach full potential, so the entry cost can be a bit deceptive.

I complimented Rothwell awhile back for being objective and helpful, and ignoring the very obvious fact he's in competition when it comes to vinyl replay. Here he's praising Sansui, when he could easily say "If you're not happy with your phono stage, try one of mine." [Praise can be embarrassing, so just let it pass...]

 

[lini]

(...) I'm also not sure how to calculate the gain of my MC stage. (...)

That simply is line input sensitivity to phono input sensitivity, so in your case factor 2000 for MC and 80 for MM (200 mV / 0.1 mV and 200 mV / 2.5 mV) or respectively pretty exactly 66 and 38 dB, with MC gain here including MM gain due to the MC stage being a pre-preamp stage, as rwa has already mentioned above.

Greetings from Munich!

Manfred / lini

 

[Balifly]

Is it possible that my MC head amp has a high gain of 68dB ?

I assume the fact that it's transformer based with 24 FETS and not op amps make a difference in SQ too?

Can someone please confirm that a ~.15mV cart would be the best match for the listed specs of my MC stage?

The Sansui AU-X1 has the .

The Sansui AU-X1 can handle any lomc cartridge with out put as a low as .

I have not encountered any lomc with out put lower than 0.14 mV.

But there are always exceptions and many that I have not even heard of yet.

https://www.vintageshifi.com/repertoire-pdf/pdf/telecharge.php?pdf=Sansui-AU-X1-Brochure.pdf

 

[Vintagear]

...it is the design using whatever components the designer is comfortable with. and
often less to do with bean counters and costs - Japanese vendors tend to create
house sounds so their products have similar SQ and one way they do this is use
carbon film resistors which are generally cheaper than the boutique metal films.
but some will say these CF resistors are due to bean counters...

Interesting point, that's good to know. At least it looks like they kept the bean counters away from this design because they used metalized film resistors.

suppose no one answers your question - are you willing spend, say 10K for
a custom build of a cartridge to yield this questionable .15mv at some
frequency and to find some LP that plays back with this custom cartridge
at EXACTLY 0.15mv?

I was actually looking for something like a used Denon DL-S1 but I will keep an eye out for carts in the ~.20mV range.

Yes, this appears to be from a time when audio engineers were competing to get the best out of phonostages and amplifiers in general, and the market for this kind of stuff was big enough to interest large-scale manufacturers with considerable R&D budgets. The number of FETs paralleled-up in the pre-preamp to reduce noise is quite impressive.

That carries a lot of weight coming from someone like you. Thanks for the honesty. It sounds amazingly good too, this thing can go toe-to-toe with some very nice DACs I've had in here.

It was made in the early '80s, before CD's blitzkrieg, and Vinyl still ruled, the main source in every system. Before it became an 'optional extra' or eliminated entirely. I have a Denon receiver, TOTL at the time, and it too has a fine phono stage, with both MM and MC.

Sometimes I use it in place of my separates, but keeping my best carts/arm/TT and speakers — I hear slight loss in SQ, but not satisfaction. And some less audiophiliac friends prefer it: a bit less detail may give them a more 'holistic' presentation. And the Tuner is very good. Sometimes the convenience of an all-in-one component, needing so little space and without a jungle of cables, outweighs the quest for "the absolute sound."

A disadvantage of such designs is they often share a power supply with a great honking power amp, so loud passages or dynamic transients can disrupt the subtler needs of the phono section. But the new species of stand-alone units often use a basic wall-wart, also a limiting factor. Today's temptingly affordable standalone phono preamps may require an equal extra expenditure to reach full potential, so the entry cost can be a bit deceptive.

I complimented Rothwell awhile back for being objective and helpful, and ignoring the very obvious fact he's in competition when it comes to vinyl replay. Here he's praising Sansui, when he could easily say "If you're not happy with your phono stage, try one of mine." [Praise can be embarrassing, so just let it pass...]

Agreed, the assistance and objectivity that Rothwell provided definitely put him at the top of my list in the event I look to get an external phono stage or step-up for my other system. Very helpful and knowledgeable indeed.

Thank you all for your assistance, clarification and confirmation on this.

 

[bimasta]

Thank you all for your assistance, clarification and confirmation on this.

Nice to see someone using AK's great format options — font enlarged and bolded, focuses the attention. Compared to most sites, AK is quite sophisticated.