Jump to content

Sign in to follow this  
Telecine

Capacitance Loading of MM and MI Cartridges

Recommended Posts

I have a variety of MM and MI carts, a variety of phono stages and a variety of turntables and arms. 

 

I am looking to have @andyr make me up some loading plugs. I have my favorites for MC carts but am looking for recommendations for MM and MI carts.

 

The options would appear to be capacitance loading versus resistance loading.

 

Capacitance loading to achieve 100pf - 400pf and resistance loading to achieve 37k - 42k as opposed to 47k.

 

Any recommendations?  

Share this post


Link to post
Share on other sites
1 hour ago, Telecine said:

I have a variety of MM and MI carts, a variety of phono stages and a variety of turntables and arms. 

 

I am looking to have @andyr make me up some loading plugs. I have my favorites for MC carts but am looking for recommendations for MM and MI carts.

 

The options would appear to be capacitance loading versus resistance loading.

 

Capacitance loading to achieve 100pf - 400pf and resistance loading to achieve 37k - 42k as opposed to 47k.

 

Any recommendations?  

 

 

My old McLaren preamp has two phono inputs.  One has variable loading, resistance 33k or 47k, capacitance 0, 100, 200, 300pf.

Share this post


Link to post
Share on other sites

Most MM /MI carts work best with the loading between 100pf and 300pf (i run mine on 200pf).

 

Some of my phono stages actually have 50k as resistance (most are 47K)... perhaps allow for 50k too?

Share this post


Link to post
Share on other sites
Just now, Douglas HiFi said:

Most MM /MI carts work best with the loading between 100pf and 300pf (i run mine on 200pf).

 

Some of my phono stages actually have 50k as resistance (most are 47K)... perhaps allow for 50k too?

I wouldn't think the 3K difference matters much.  If you want to try a different loading, I would try bigger differences.

Share this post


Link to post
Share on other sites


18 minutes ago, Douglas HiFi said:

Most MM /MI carts work best with the loading between 100pf and 300pf (i run mine on 200pf).

 

I'm assuming, Simon, you do know that if you choose 200pF loading on the phono stage ... the cart 'sees' more than this.  :)

 

Total load for the cart will be whatever the phono stage has, plus:

  • headshell wire capacitance
  • arm wire capacitance, and
  • phono cable capacitance.

All the above, together, is what has to equal the recommended cap load for an MM cart.  MI carts - well, Grados, anyway - are not sensitive to cap load.

 

18 minutes ago, Douglas HiFi said:

Some of my phono stages actually have 50k as resistance (most are 47K)... perhaps allow for 50k too?

 

50K is a peculiar number - given that, these days, MM & MI carts expect 47K.  Though there are some old (70s/80s) Japanese carts that like 100K - which is why this is the default in my Muse MM ... used together with a pair of parallel input load resistors, to get the desired value.

 

Andy

 

Share this post


Link to post
Share on other sites
7 hours ago, andyr said:

 

I'm assuming, Simon, you do know that if you choose 200pF loading on the phono stage ... the cart 'sees' more than this.  :)

 

Total load for the cart will be whatever the phono stage has, plus:

  • headshell wire capacitance
  • arm wire capacitance, and
  • phono cable capacitance.

All the above, together, is what has to equal the recommended cap load for an MM cart.  MI carts - well, Grados, anyway - are not sensitive to cap load.

 

 

50K is a peculiar number - given that, these days, MM & MI carts expect 47K.  Though there are some old (70s/80s) Japanese carts that like 100K - which is why this is the default in my Muse MM ... used together with a pair of parallel input load resistors, to get the desired value.

 

Andy

 

 

Hi Andy,

yes - absolutely correct regarding total of all capacitance in the signal chain... very important.

 

The problem is a lot of RCA/Turntable cables only stipulate "low capacitance" and it is impossible to tell.....

(some other cable manufacturer's are great and do tell you the actual  capacitance of the cable).

 

It has been my experience that most MM carts sound best when the phono pre is set between 100-200pf.

 

Yeah - the 50k is a little odd - but it seems a few high end Japanese brands have had the option of either 50k or 52k as well as 47k and 100k.

The phono I have with the 50k setting is a real smooth, full sound.... hard to know if that is the overall sound or due to the fact that it is a fixed 50k input on MM rather than 47k.

 

My main phono stage has selectable 100,200 or 300pf for the MM input and depending on the cartridge I toggle between 100 and 200pf on the phono pre.

 

:)

 

 

Edited by Douglas HiFi

Share this post


Link to post
Share on other sites

Tele you have widely gone to the main man

Just pay him and listen to the music.

what is your main phono these days?

the guys will want photos

Share this post


Link to post
Share on other sites

True @djb

 

The main system has a Melos Reference two box tube-based phono as well as a phono stage in the Classe Audio preamp.

 

Too lazy to take photos.

Share this post


Link to post
Share on other sites


1 hour ago, Telecine said:

Too lazy to take photos.

That's an offence here, you know this. You walk a fine line...

Share this post


Link to post
Share on other sites
10 minutes ago, Luc said:

That's an offence here, you know this. You walk a fine line...

I think that I can dodge that bullet because I won't be using the loading plugs for either of these phono stages. They are for phono stages in other systems ;) 

Share this post


Link to post
Share on other sites

Hoping to get a little help on this too.

 

Have 2 phonos built into my Linn Akurate and a valve Phono in my MA2275

 

Linn is 48k ohm, 68pF

McIntosh is 47k, 65pF

 

Most TTs I am looking at have an Ortofon Red or Blue that recommend 47k and 150-300pF

 

I understand cables will add a little. capacitance, Is there any issue here or should I be looking at different carts?

 

I think the Linn may have some adjustment but I can't see in the software what it is without having something connected. The Mac doesn't have any settings

 

Thanks

Edited by Bunno77
.

Share this post


Link to post
Share on other sites

You are probably fine, taking into account the cable but I obtained a set of capacitance loading plugs and a set of Y connectors from @andyr so that I could add a bit for some carts.

Share this post


Link to post
Share on other sites


Hello Guys,

May I add my pinch of salt ?

First, Mr Holman (of THX fame) made a fine pre-amplifier called the APT Holman and this little beast has different capacitance/charge available for the turntable cart...

Next, this little fella : https://www.aliexpress.com/item/32613345424.html?spm=a2g0o.productlist.0.0.1ca11885fb3w00&algo_pvid=5afb33c4-b408-49d1-ba4f-de6887013f62&algo_expid=5afb33c4-b408-49d1-ba4f-de6887013f62-13&btsid=3473d465-429e-4924-b499-7a2628b304df&ws_ab_test=searchweb0_0,searchweb201602_10,searchweb201603_53

can measure the capacitance of the phono cable from the RCA plug to the arm plug where the cartridge fit. (you have to remove the cart for capacitance measurement) Once you've got the total cable capacitance value, you can measure the inductance and resistance value of the cart coils using the same device and decide for yourself what to do with these figures.

I've done this and set the Holman preamp to the 200 pF the Grado requires and use that setting with all my carts, most of them being AT or Ortofon... and enjoy the music.

So your mileage will vary 😉

Share this post


Link to post
Share on other sites
7 hours ago, georgesgiralt said:

Hello Guys,

May I add my pinch of salt ?

 

Now, I'll include my pinch of pepper.  :)

 

Quote

First, Mr Holman (of THX fame) made a fine pre-amplifier called the APT Holman and this little beast has different capacitance/charge available for the turntable cart...

 

You can make an infinite variety of loadings available to the cart by:

  • either having a second pair of input RCAs connected in parallel with the main ones (which take the phono cable)
  • or using Phoenix connectors on the PCB (connected in parallel with the input RCAs).

"Loaded" RCA plugs then fit into the parallel RCAs / resistors into the Phoenix connectors.

 

Quote

I've done this and set the Holman preamp to the 200 pF the Grado requires and use that setting with all my carts, most of them being AT or Ortofon... and enjoy the music.

 

 

What Grado do you have?

 

I ask because I used to own a wood-bodied Grado (first the Reference 'Platinum' and then the Reference 'Reference1') and their spec sheets said "insensitive to capacitance load "!

 

AIUI, this is because Grados are "Moving Iron" carts - not "Moving Magnet"?

 

Andy

 

Edited by andyr

Share this post


Link to post
Share on other sites

my Grado is an old GTE+1 which was cheap in the early '80s when I bought it but I did not regret buying it and enjoyed it since.

Share this post


Link to post
Share on other sites

If you want to get fussy about mm loading measure the cartridge's inductance and do a little bit of maths

Share this post


Link to post
Share on other sites


Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...