Capacitance for MMC cartridges

The B&O specs say the capacitance should be <=400pf. I'm curious to hear people's experiences using different loading within that range and how it did or didn't change the sound.

Matt

 

I can't tell you much because I only have experience with the MMC20CL and MMC20EN, both used on my 4002 turntable through a Musical Surroundings Phenomena. The Phenomena only has settings for 200 or 300pF, and my cables measure 90pF from the deck.

Anyway, I can't hear any difference between the two settings on the preamp. The MMC20CL does sound a little more lively running at 100kHz rather than 50kHz, so that's where I use it.

I have ordered a Signal Cable Silver Reference cable to replace my Furez cable but haven't received it just yet.

Has anyone seen inductance figures for any of the MMC's?

Do you mean 50kohm and 100kohm?

 

I haven't seem inductance figures for the MMCs.

There are capacitance in all coils and wires, if B&O knew that this would have any influence on the sound they would have provided oxygen free copper left and right twisted 40 strand wires for the connecting cable, the plug would have been soldered with high silver solder tin, the plug would have had gold pins. The main thing with vinyl is the source and the cartridge, why bother with "high end cables" if you source or cartridge is less than the absolute best. If inductance high or low, B&O would have put a cap in somewhere in the circuit, not to speak of the preamp.    

Apparently B&O knew that capacitance does have an effect on the sound, otherwise they wouldn't have bothered specifying a range of <=400pf.  

I'm sure B&O engineers knew what they wanted and used the appropriate materials of the time for their purposes. That doesn't mean that there won't be a difference in damping or frequency response if you experiment with different loading schemes. Whether one hears the difference or not is the question.

I wish I had measured the capacitance at the DIN end of the cable before removing it, but in my case I had no way of listening to the turntable at all with the Din in place and would prefer to have the option of trying different cables. I realize it may seem blasphemous to some.

Yes, I mean kOhms. 

Most good phono preamps and many higher end preamps used to offer switches to change the loading of the cartridge. I have a Proton integrated amp from the mid 80's that has a switch to change capacitance loading. Of course, at the dawn of the CD era the phono preamp was still considered an important part of an audio product, it even got gold RCA plugs on the Proton while all other sources were regular silver jacks.

when I spoke to a technician at the factory about 20 years ago, he told me that the Inductance (mH ) value for the MMC20CL was around 200mH per channel and the recommended capacitance pF value combined around 300pF ( 220pF for the phono stage and then the cart + tonearm 80pF )

The DIN ( and IEC) standards of 1973 seem to support this, ie IEC says 300pF, measure a Technics or Denon arm and the capacitance will be around 70 to 80pF

however, looking at the Hagtech loading calculator, it seems that using the 400mH inductance value and 300pF value gives a resonance bump at around 14.5kHz, this was most likely what B&O were happy with at the time, and not many people over 40 can hear test tones above 15kHz  

http://www.hagtech.com/loading.html

when I saw this on a MMC 20 CL spec page -     "Cable capacity from 100 pF to 1,500pF (not critical) "

and punch in these values on the Hagtech calculator, the extreme 1500pF value and 400mH inductance it is still ruler flat (the FR) until 6.5kHz, which is still comfortably above the highest frequency note that a piano can play ie 4.2kHz 

http://music.stackexchange.com/questions/6229/why-is-the-highest-frequency-on-a-piano-4186-hertz

the good news is that using better cables ( with very low capacitance values of less 50pF a metre, a ruler flat frequency range past 15kHz is what most people strive for these days, and using modern phono stages from the likes of Graham Slee the pH inside the phono can be as low as 100ph 

 

 

a few people have asked me what model of Graham Slee phono preamp I use, it is the Gram Amp II Special Edition that I bought around 2003

it works well with all the MMCx carts and SMMCx carts I have in my collection, it has a high gain and the Graham Slee units are all hand built and made in England, which is a quality I admire :-) 

Beogram 8002    Tonearm Pins to end of D-102 cable -  capacitance measured at 92 pF

Graham Slee Gram Amp II Special Edition   -  internal value of 100 pF capacitance (confirmed by Graham) 

NB  Van den Hul D-102 MK III cable  spec is 37 pF a metre  ( I used only 33cm for my phono cable interconnect) 

So pretty much ruler flat to 18kHz  -  not bad ! 

 

 

That looks a nice unit, and the power supply. A bit more pricy than the 'for beer money' comment in the review (unless you spend a fortune on beer!). For hand built in the UK though, if it's as good as you say, it may be worth investigating.

Dave.