Keep it simple, Aikido designs are fine if your using an unregulated power supply! But who wants to use a blah power supply, when one can use a few more components and make a great power supply, and use fewer components in the signal path!!
Completely agree. That was the reason for me to start questioning the Chinese clone of Marantz. The simplicity, point to point soldering (avoiding PCB board) and less signal paths. However as we can see now, the problem is in VERY high input and what worse, the additional volume control will effect the overall quality sound for the pre-amp.
Apart from volume control (from RCA inputs into the pre-amp PCB board) shouldn’t this input from external audio sources be handles within the tube by resistors?
The input tube looks like can handle 3V from CD, but expected distortion would be much higher. You can reduce the gain but changing 75K feedback res. to lower value. The sound would be quite different. The sch you shown already down from 82K of original.
It may be best for you to choose a good stand alone tube or ss phono stage, and use it with a
very inexpensive Chinese JC2 line amp copy. This line amp copy has been said to be good by the
original designer, JC.
PCB only: ?JC-2???? ?????? ?3?????-??????
Complete line preamp: http://www.aliexpress.com/item/imtate-Mark-JC-2-preamp-finished-product/2044830052.html
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i see a lot of clones from Asia about this Marantz 7 preamp....
i even made one out of the 13fm7 tube,
i have seen kits being sold using the 6au6 and 6V6 run as triodes...
topology is basically high open loop gain tamed
by global negative feedback, lots of it...
probably to mitigate the effects of tube aging...
i have been asked to make this preamp lots of times....
i make the aikido or the broskie ccda instead,
i especially like the ccda for its simplicity and sheer good sound...
i even made one out of the 13fm7 tube,
i have seen kits being sold using the 6au6 and 6V6 run as triodes...
topology is basically high open loop gain tamed
by global negative feedback, lots of it...
probably to mitigate the effects of tube aging...
i have been asked to make this preamp lots of times....
i make the aikido or the broskie ccda instead,
i especially like the ccda for its simplicity and sheer good sound...
Looks there is a general consensus here that the MARANTZ 7C line stage is a lousy poorly designed circuit which doesn't worth to be duplicated and can easily be outperformed by allmost anything else. Then , I'm wondering why the 7C is so highly respected by many audiophiles and considered as one of the best vintage preamps ? (and also one of the most sought after and expensive). Or is it only the chinese (PCB) implementation of that circuit which is so bad ?
99% of the time, yes. I can think of a few exceptions, but very, very few.
puzzles me no end also...the SP-3 has a following here too...
i have learned so far that with tubes, less is more.....
even the simplest of a circuit can deliver the goods...
This is great philosophy!! Manufactures, specifically In High-end gear, have used redundant curcuitry merely to increase profit margins, the old saying "more is always better" always catches the eye, of those willing to spend a butt load of money for what they think is the best, and has the best sound!
i have also learned the in spite of what people say they are after the sound of a tube amp,
reality is they are more swayed by the looks of amps...😱
still there are those who spurn cheap amps as low quality.....
When I was quite a bit younger and less experienced I built a clone of an SP-3 without the tone controls; I could not have been much more disappointed in the performance of that project - my first scratch built tube project, I tore it apart and designed my own shortly thereafter in self defense.
I repaired a few over the years and found them very old fashioned sounding.
I repaired a few over the years and found them very old fashioned sounding.
LOL! tell that to the local boys Kevin....... have had little success convincing them....
i gave up....they tell me, my preamp has only two tubes, how can it be better?
i just smiled and nodded if only not to provoke violence.....
i gave up....they tell me, my preamp has only two tubes, how can it be better?
i just smiled and nodded if only not to provoke violence.....
You can lead a horse to water...
If it was so great I assume ARC would still be making something similar, and so far no desire or demand for a commemorative reissue... 😉 Tell them that and they might never talk to you again.. lol
If it was so great I assume ARC would still be making something similar, and so far no desire or demand for a commemorative reissue... 😉 Tell them that and they might never talk to you again.. lol
I recommend a 12B4 linestage with a active or perhaps a transformer plate load and with gas regulator tubes. The cool purple ones!
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Do a search for Bruce Rozenblit's line level preamp. It's a nice simple design using two 12AU7 tubes for the entire amp. I would suggest a 12X4 if you want a tube rectifier. Start with a Hammond chassis (Search Hammond Manufacturing). The design gives a high impedance output and a low impedance one as well. Point to point isn't difficult if you start by laying out the positions of the major components, power transformer, PSU capacitors, tube sockets, volume control and RCA jacks. You can buy terminal strips from Tube Depot or eBay to locate the passive parts around the tube sockets. You should check out Hammond, or Edcor or Antek for the power transformer. Mouser sells ALPS volume controls and are reasonable. They also have an inexpensive selector switch that works well, I've forgotten the name? And you could probably build it for about $140 dollars or so.
My two cents.
P.S. The Akido designs are very nice. I built one point to point. It was very quiet, very clean sounding.
My two cents.
P.S. The Akido designs are very nice. I built one point to point. It was very quiet, very clean sounding.
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Hi experts
I interesting in the Marantz 7 line stage, order 6n2p-ev and the other parts, chip one, only for testing and Then replace with tube 12ax7 and good cap's.
Denny and others talk about the gain issue, in my case I have:
DAC PCM1796, the output of this DAC is 4mA, I put passive I/V 50-25 ohm resistor, so the voltage is ~ 0.2-0.1, I think 20db gain is fine for my setup.
What do you think?
now i have SRPP base on 6n3p-ev with 100 ohm RK. 20db gain
thanks
I interesting in the Marantz 7 line stage, order 6n2p-ev and the other parts, chip one, only for testing and Then replace with tube 12ax7 and good cap's.
Denny and others talk about the gain issue, in my case I have:
DAC PCM1796, the output of this DAC is 4mA, I put passive I/V 50-25 ohm resistor, so the voltage is ~ 0.2-0.1, I think 20db gain is fine for my setup.
What do you think?
now i have SRPP base on 6n3p-ev with 100 ohm RK. 20db gain
thanks
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