Hi Guys and Girls,
Just want to get an idea of the most popular loading for MC and MM carts.
Want to use two 1-pole, 12 step switches: one for resistance and one for capacitance.
I know this topic can cause some controversy, so please, let's keep it friendly. If my plans are over-kill, and I'm worrying too much, feel free to let me know. Seems that this could be overly done, but there are lots of opinions on loading and tons of carts out there, so I'd like to make my phono pre as flexible as possible. It's Jfet input phono pre.
Skimming over the internet, I have found some of these values and some I have used to fill in the gaps. I would like to use low resistance in case I decide to use a step-up transformer with a MC, like a .25mV output, of which I own. Also soon to be owner of 1.6mV MC.
Some of what I read indicates no capactive loading is necessary for MC carts.
What's your opinion?
Just copy my list and edit it in a new post. I'm pretty sure I'm not the only one with this question, so you'll be helping others as well.
Thanks,
Vince
Cart Loading:
MC Resistance Loading
10 ohm
20
40
60
80
100
150
300
1500
MM Resistance Loading
30k
47k
100k
MC Capacitance Load
500pF to 2000pF
MM Capacitance Loading
50pF to 470pF
Just want to get an idea of the most popular loading for MC and MM carts.
Want to use two 1-pole, 12 step switches: one for resistance and one for capacitance.
I know this topic can cause some controversy, so please, let's keep it friendly. If my plans are over-kill, and I'm worrying too much, feel free to let me know. Seems that this could be overly done, but there are lots of opinions on loading and tons of carts out there, so I'd like to make my phono pre as flexible as possible. It's Jfet input phono pre.
Skimming over the internet, I have found some of these values and some I have used to fill in the gaps. I would like to use low resistance in case I decide to use a step-up transformer with a MC, like a .25mV output, of which I own. Also soon to be owner of 1.6mV MC.
Some of what I read indicates no capactive loading is necessary for MC carts.
What's your opinion?
Just copy my list and edit it in a new post. I'm pretty sure I'm not the only one with this question, so you'll be helping others as well.
Thanks,
Vince
Cart Loading:
MC Resistance Loading
10 ohm
20
40
60
80
100
150
300
1500
MM Resistance Loading
30k
47k
100k
MC Capacitance Load
500pF to 2000pF
MM Capacitance Loading
50pF to 470pF
You will need 2-pole switches, unless you want separate ones for each channel. 12 different capacitance options seems like overkill. MC may need none at all; MM can be handled by 3 or 4 at the most. Ortofon MMs will probably need the highest capacitance but even then only 2-300pF as the cable will add some. How about 0-100-220-330pF?
Be careful about wiring, as that will add capacitance and hum/interference pickup. Personally, I would use a small DIP switch on the PCB to keep connections short or even a few wire tags and change it with soldered links. The last thing you want is intermittent contacts.
Be careful about wiring, as that will add capacitance and hum/interference pickup. Personally, I would use a small DIP switch on the PCB to keep connections short or even a few wire tags and change it with soldered links. The last thing you want is intermittent contacts.
Unless your pre-amplifier is designed for direct use with LOMC cartridges most of the MC values you list will not be needed as you will not have the required gain or noise performance to connect them directly. Loading in this instance would either be handled by a head amp or SUT most of which seem to like secondary load resistances of 10K - 47K IMVLE.. HOMC generally are designed for use directly into 47K although you may empirically determine that they perform better into a lower resistance..
Thanks Kevinr.
I misunderstood this chart. The low loads are for the SUT impedence, not the preamp that comes after the SUT.
Discussion on MC Cartridge Loading
Maybe 80 ohm would be the lowest?
I'm new to analog altogether, so I probably am over doing it because I don't understand it all very well. I just noticed that the range of cartridges is huge, even inside the MC genre of carts.
Maybe some sort of a DIP off the board will do, then I can just buy resistors or caps as I need them.
A friend has an AR phono and we were listening to different resistor and cap loads to determine what he liked best. He was able to change settings at-will and I liked this function. I don't mind it being more manual when it comes to changing. I just don't like permanent where change could take place, e.i., unscrew the board, unsolder resistors, etc. Know what I mean?
So, I should concentrate more on what values are important to me now. I get it.
Maybe just bracket 150 ohms and 47k ohms?
I just built the Pearl II, if I didn't mention that bit.
Maybe some sort of a DIP off the board will do, then I can just buy resistors or caps as I need them.
A friend has an AR phono and we were listening to different resistor and cap loads to determine what he liked best. He was able to change settings at-will and I liked this function. I don't mind it being more manual when it comes to changing. I just don't like permanent where change could take place, e.i., unscrew the board, unsolder resistors, etc. Know what I mean?
So, I should concentrate more on what values are important to me now. I get it.
Maybe just bracket 150 ohms and 47k ohms?
I just built the Pearl II, if I didn't mention that bit.
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Last edited:
Hi Vince
Interesting to see your thread pop up.
I am trying to work out a similar thing at present.
I have started on a new phono-pre.
The 2 previous ones were both for MM only, & had 47K Ohms & a few pF's on the board.
The new phono-pre, will mainly be for a Denon DL-110.
But since I have 2 other TT's and several different MM cartridges...
...some flexibility would seem an advantage.
Also am building this phono-pre for a friend as well ( 2 pre's )...
...he will run a Denon DL-110 also, but could want MM compatibility as well.
Yeah...
3 solutions come to mind as already said.
1. Dip switches
2. Rotary switch.
3. Plug-loading.
I have to say that I like the idea of a 'convenient' rotary-switch as your friends AR 'hot swapping' seems a must for A-B listening.
I have just got 2 double-deck 5 way rotarys to experiment with ( 12 options seemed to much to me; but what's TOO much ! dunno...why not 12 ? ).
A couple of R + C decade-boxes connected to the TT ( just kiddin' ).
No signal path connections here, as such.
I had considered 'doubling-up' rotary-poles for 1/2 the contact resistance ( although this is obviously a fraction of a potential load.
The other thing is...
...to perhaps have a 47K across the input, always...
...and then just switch your extra load R's in across it.
47K in parallel with 100R, is virtualy 100R anyhow.
Can't decide on the values at present.
Will be interesting to hear more of what people think about this.
It seems you want 'pre-installed' loading, as the AR and other pre's have.
They don't know what cart you gonna run, so give a choice.
Some commercial offerings just have a 2 way option.
What did the AR have ?
Maybe do the same ?
Cheers.
Si.
Interesting to see your thread pop up.
I am trying to work out a similar thing at present.
I have started on a new phono-pre.
The 2 previous ones were both for MM only, & had 47K Ohms & a few pF's on the board.
The new phono-pre, will mainly be for a Denon DL-110.
But since I have 2 other TT's and several different MM cartridges...
...some flexibility would seem an advantage.
Also am building this phono-pre for a friend as well ( 2 pre's )...
...he will run a Denon DL-110 also, but could want MM compatibility as well.
Yeah...
3 solutions come to mind as already said.
1. Dip switches
2. Rotary switch.
3. Plug-loading.
I have to say that I like the idea of a 'convenient' rotary-switch as your friends AR 'hot swapping' seems a must for A-B listening.
I have just got 2 double-deck 5 way rotarys to experiment with ( 12 options seemed to much to me; but what's TOO much ! dunno...why not 12 ? ).
A couple of R + C decade-boxes connected to the TT ( just kiddin' ).
No signal path connections here, as such.
I had considered 'doubling-up' rotary-poles for 1/2 the contact resistance ( although this is obviously a fraction of a potential load.
The other thing is...
...to perhaps have a 47K across the input, always...
...and then just switch your extra load R's in across it.
47K in parallel with 100R, is virtualy 100R anyhow.
Can't decide on the values at present.
Will be interesting to hear more of what people think about this.
It seems you want 'pre-installed' loading, as the AR and other pre's have.
They don't know what cart you gonna run, so give a choice.
Some commercial offerings just have a 2 way option.
What did the AR have ?
Maybe do the same ?
Cheers.
Si.
Agree, Don - that's the way I do it. In fact, for a MM phono stage, I would suggest 2 parallel pairs of RCAs ... so you can adjust 'C' as well as 'R' load.
The issue with using switches at such low signal levels is that they always degrade the SQ, compared to if the switches weren't there.
Regards,
Andy
Let me give you a couple of examples:
1. I modified a phono stage which I had bought from a local dealer (who designed it); I added a simple switch to connect the R & L signals together, to make it mono. (It's nice to be able to have mono when you're setting up your system, sometimes.) This switch substantially degraded the sound stage, compared to before ... so I removed it!
2. This same dealer has a Doge 8 preamp (which he loves). The Doge 8 comes with a switch for MM/MC - Mike told me that the MM circuit sounded substantially better after he had disabled the switch (he has the top Grado MM, the 4mV Reference Reference1, so he doesn't use the MC section).
Regards,
Andy
1. I modified a phono stage which I had bought from a local dealer (who designed it); I added a simple switch to connect the R & L signals together, to make it mono. (It's nice to be able to have mono when you're setting up your system, sometimes.) This switch substantially degraded the sound stage, compared to before ... so I removed it!
2. This same dealer has a Doge 8 preamp (which he loves). The Doge 8 comes with a switch for MM/MC - Mike told me that the MM circuit sounded substantially better after he had disabled the switch (he has the top Grado MM, the 4mV Reference Reference1, so he doesn't use the MC section).
Regards,
Andy
Space Egg, I'm receiving the DL-110 on Dec 3rd. Do you like it? I have a heavily modded 103R now.
One site described using a large 1 meg + resistor in parallel always and figure for other parallel values.
Using a DIP switch one can call up many values with less resistors.
Phono Cartridge Loading
I think adjusting the load is a bit different than using a tone control.
One site described using a large 1 meg + resistor in parallel always and figure for other parallel values.
Using a DIP switch one can call up many values with less resistors.
Phono Cartridge Loading
I think adjusting the load is a bit different than using a tone control.
Saw this on the wonderfull WWW...
Of course with any scheme using 'fixed-values'...
...you may just miss 'the sweet-spot' by a country-mile !!!
Saw this on the WWW somewhere.
Simples !
The guy made 2 precision 'calibrated pots'...dialed in the values...
BOOM !
Job done !
Can always replace the pots with a fixed value if you're worried about them.
BINGO ! 'sweet-spot' found for ANY cartridge.
Smart dude...
...lateral-thinking !
Si.
Of course with any scheme using 'fixed-values'...
...you may just miss 'the sweet-spot' by a country-mile !!!
Saw this on the WWW somewhere.
Simples !
The guy made 2 precision 'calibrated pots'...dialed in the values...
BOOM !
Job done !
Can always replace the pots with a fixed value if you're worried about them.
BINGO ! 'sweet-spot' found for ANY cartridge.
Smart dude...
...lateral-thinking !
Si.
Attachments
Hi Vince
You might be able to tell me if YOU like it first...
...cos I don't have one yet !
My friend is importing 2 from the USA for us both.
( considerably cheaper, than in 'rip-off Britain' ! )
Anyhow...
...seems like just about every living / hearing being on the planet since it was born in 1982 !...
...recs. it's A WINNER !
Very FLAT...
...what more could you ask for ?
Mega-detail...
...& way less surface-noise reproduced.
None of this 'rising-response' tosh...
...like some 'audiophile' carts either.
The Japs know how to listen...
...& they like things FLAT !!!!!
Cheers.
Si.
wot u think of the pot box ?
You might be able to tell me if YOU like it first...
...cos I don't have one yet !
My friend is importing 2 from the USA for us both.
( considerably cheaper, than in 'rip-off Britain' ! )
Anyhow...
...seems like just about every living / hearing being on the planet since it was born in 1982 !...
...recs. it's A WINNER !
Very FLAT...
...what more could you ask for ?
Mega-detail...
...& way less surface-noise reproduced.
None of this 'rising-response' tosh...
...like some 'audiophile' carts either.
The Japs know how to listen...
...& they like things FLAT !!!!!
Cheers.
Si.
wot u think of the pot box ?
Yes, built the zen 9. Very nice amp. Its uses the aleph CCS, with special attention to load line, from what I understand. Zen 8 uses resistor load, I think. Very nice amp but the 2sk82 CCS SIT amp edges it out. The detail from the SIT is amazing, but its only 5w. The zen 9 beats the SIT in pure force only. Building the choke SIT next at 10-12 w output.
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