Hi,
Salas, it would be kind if You could add some schemtics, since the Simplistic thread covers more than 4000 threads and the numbers You quote somehow are ´hanging in free air´.
The first threads about the sSimplistic show a simple common source input stage, which could be problematic with MM-pickups due to its highinput capacitance. I assume You changed to a cascoded stage later on?
If possible I´d like to see a high-gain MC and a low gain MM-Version. I´m at the beginning of building me a TT from Technics SL5210 Motor, Rega RB300 and probabely the Ortofon 2M Black (which is high a output MM >5mV , but capacitance sensitive)
Ah Wrenchone....feels to me as if You are following the same path I walked......which will sooner or later lead You to electrostats. Welcome to the world od SuperFi *lol*
jauu
Calvin
Salas, it would be kind if You could add some schemtics, since the Simplistic thread covers more than 4000 threads and the numbers You quote somehow are ´hanging in free air´.
The first threads about the sSimplistic show a simple common source input stage, which could be problematic with MM-pickups due to its highinput capacitance. I assume You changed to a cascoded stage later on?
If possible I´d like to see a high-gain MC and a low gain MM-Version. I´m at the beginning of building me a TT from Technics SL5210 Motor, Rega RB300 and probabely the Ortofon 2M Black (which is high a output MM >5mV , but capacitance sensitive)
Ah Wrenchone....feels to me as if You are following the same path I walked......which will sooner or later lead You to electrostats. Welcome to the world od SuperFi *lol*
jauu
Calvin
Hallo Calvin ,
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Jürgen
63 db-Version , Post 2795
60 db-Version , Post 3138
60 db-Version , Post 3767
60 db-Version , Post 3069
55 db-Version , Post 4141
56 db-Version , Post 1814
52 db-Version , Post 236
48 db-Version , Post 1813
46 db-Version , Post 240
43 db-Version , Post 4600
41 db-Version , Post 1812
36 db-Version , Post 417
Jürgen
Thread biographer!
Hallo Salas ,
yes , few days ago i read the whole thread and noted all the different versions .
there is more , at the beginning .
Thanx so much for all the time you have spend , all the work and that you are
such a _consumerfriendly_ person for us + a very good teacher !
Greetings from Germany
Jürgen
yes , few days ago i read the whole thread and noted all the different versions .
there is more , at the beginning .
Thanx so much for all the time you have spend , all the work and that you are
such a _consumerfriendly_ person for us + a very good teacher !
Greetings from Germany
Jürgen
Hi Calvin
I don't think that the input capacity of the SK170 is critical for MMs. But maybe you have another JFet as suggestion...
Regards
Joao
Hi,
gain multiplies the capacitance. So with high gain values there come indeed high capacitance values which, added to the cable and input-loading cap, may be too much for a correct loading of the cartridge.
By design high gm JFETs show larger capacitance values. So if the input capacitance of a circuit is a critical parameter a different design like the cascode instead of the simple common source amp could be the solution. That is the smart thing about cascoding....keeping the capitances low and allowing for high gain.
Since we ask for considerable gain a JFET alternative needed comparably high gm as the 2SK170 but considerably lower capacitance (reverse transfer capacitance in special). It´ll be hard to find a alternative, especially when the lownoise character at rather low source impedances is also required. If one could find such a part, it probabely will be expensive and hard to source.
The Ortofon 2M-series for example are high output MM-cartidges. So their inductance value is rather on the high side and they require a lower capacitive loading.
This applies mainly to the loading of MM-cartridges, while MC catridges due to their much lower inductance values are far less critical.
The hype about the 2SK170 is not entirely without reason ;-)
jauu
Calvin
gain multiplies the capacitance. So with high gain values there come indeed high capacitance values which, added to the cable and input-loading cap, may be too much for a correct loading of the cartridge.
By design high gm JFETs show larger capacitance values. So if the input capacitance of a circuit is a critical parameter a different design like the cascode instead of the simple common source amp could be the solution. That is the smart thing about cascoding....keeping the capitances low and allowing for high gain.
Since we ask for considerable gain a JFET alternative needed comparably high gm as the 2SK170 but considerably lower capacitance (reverse transfer capacitance in special). It´ll be hard to find a alternative, especially when the lownoise character at rather low source impedances is also required. If one could find such a part, it probabely will be expensive and hard to source.
The Ortofon 2M-series for example are high output MM-cartidges. So their inductance value is rather on the high side and they require a lower capacitive loading.
This applies mainly to the loading of MM-cartridges, while MC catridges due to their much lower inductance values are far less critical.
The hype about the 2SK170 is not entirely without reason ;-)
jauu
Calvin
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Hi Calvin
thanks for the reply and the facts in which I agree. Anyway, who uses MM carts - ok, the Grados - nowadays? As well we can use cables with low capacitance...
Can you share your listening experience with your MM-cartridge regarding "common source" and "cascoded input stages" ?
Hi,
I´ll soon get me the 2M Black. I never liked the tonality and resolution of the Grados. At first I was searching for a nice MC. But apart from the ever present DL103 I only found the AT33PTG, which now is hard to find these days even on ebay. So I asked a person who knows my likes and my gear and whom I trust in his words about sonic character of pickups.
After him I wouldn´t find a MC-pickup around 300€ that could cope with the Ortofon. Besides Ortofon ´designed´ the 2M obviously as partners for Rega-arms. And though I have an excellent Phono-stage -optimized rather for MC than MM) I think I´ll build a simple JFET-Phono for this cartridge too. With a nominal output of >5mV it doesn´t need so much gain and I have a huge bunch of 2SK373 and some BF246A lying around.
If done well the cascode shoud perform acoustically transparent. Sure would I prefer the common source stage simply because of its simplicity, but if the input impedance of this stage doesn´t load the pickup correctly, it´s no matter of easyness or taste but a matter of choice of the best fitting circuit design.
jauu
Calvin
I´ll soon get me the 2M Black. I never liked the tonality and resolution of the Grados. At first I was searching for a nice MC. But apart from the ever present DL103 I only found the AT33PTG, which now is hard to find these days even on ebay. So I asked a person who knows my likes and my gear and whom I trust in his words about sonic character of pickups.
After him I wouldn´t find a MC-pickup around 300€ that could cope with the Ortofon. Besides Ortofon ´designed´ the 2M obviously as partners for Rega-arms. And though I have an excellent Phono-stage -optimized rather for MC than MM) I think I´ll build a simple JFET-Phono for this cartridge too. With a nominal output of >5mV it doesn´t need so much gain and I have a huge bunch of 2SK373 and some BF246A lying around.
If done well the cascode shoud perform acoustically transparent. Sure would I prefer the common source stage simply because of its simplicity, but if the input impedance of this stage doesn´t load the pickup correctly, it´s no matter of easyness or taste but a matter of choice of the best fitting circuit design.
jauu
Calvin
I posted the plots in the Pass forum, the BF862 is (very) slightly less noisey than the 2SK170 and has much less C. Check out the graphs and see what you get if you don't sort
There is such a part, the Philips BF862. Easy to source, current production, cheap. Noise a bit better even. Capacitance, 3 times less. Gm, more. ''Problem''? Surface mount.
P.S. Hey, cross posted with Scott. Regards!
Those Ortofons are very good carts. Use a capacitance multiplier local to your cascoded head amp and a 100k Vishay bulk foil trimmer for MM input load, no added pF capacitor. Can give surprising range of tuning the cart.
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