The fact that I joined the IT world extremely late (first computer in 2006) means that I have no choice but to design using the datasheets. I do hope to learn LT spice at some time. I had to learn some Russian when I went to the Tchaikovsky competition in 1990 so with the help of a dictionary I can figure out the Soviet datasheets if there is no translation.
I suppose that the low gm of this 6n14p relative to the 6j9p means that it is much less likely to be troublesome. I don't know what the other factors are; probably mostly a matter of geometry. Anyway, that seems to be a good find Kevin and not an obvious choice at first glance.
I suppose that the low gm of this 6n14p relative to the 6j9p means that it is much less likely to be troublesome. I don't know what the other factors are; probably mostly a matter of geometry. Anyway, that seems to be a good find Kevin and not an obvious choice at first glance.
6N14P Ia/gm looks better for quieter 1/f noise at 5mA and gm=4.5 at Vgk=-1V μ=20. Not that much of μ for head amp concept unless with distributed or second stage located RIAA EQ.
Well of course since it is a cascode gains of 36dB or more can be attained with this tube and a 12K plate load resistance. See the new thread..
Hi Kevin,
Great thread. I'm looking forward to you receiving the ECC84. I think they said about 5 days. We will see. I don't know about customs. They are send without value.
Btw. I have recently got a Thorens TD318 for my son in trade for building a power supply for a friends ML-2 pre-amp. Also, I bought a Thorens TD-320. There will be some vinyl playing here I think.
Cheers,
Mogens
Great thread. I'm looking forward to you receiving the ECC84. I think they said about 5 days. We will see. I don't know about customs. They are send without value.
Btw. I have recently got a Thorens TD318 for my son in trade for building a power supply for a friends ML-2 pre-amp. Also, I bought a Thorens TD-320. There will be some vinyl playing here I think.
Cheers,
Mogens
Will let you know when they get here. I can say the 6N14P sound quite good. I'm in general happier with them than the 6J9P.. I am looking forward to evaluating and listening to the ECC84.. I will do the lot 6N14P, ECC84 and PCC84 all at once and put them in the vacuum tube spice models thread over in tubes / valves forum.
The new phono pre thread is here: http://www.diyaudio.com/forums/analogue-source/254641-muscovite-mini-ii-6n14p-phono-stage.html
The new phono pre thread is here: http://www.diyaudio.com/forums/analogue-source/254641-muscovite-mini-ii-6n14p-phono-stage.html
In terms of further possible improvement to the Mini (not the mini II) I would recommend replacing C2 and C7 with five 1uF capacitors in parallel. The problem really is that the screen cap is providing the current for the AC portion of the screen current swing which is why its quality is so critical. Ultimately the K71-4 did not prove satisfactory in this location.
I have switched to a cascode front end so have not yet tried this change, however it is consistent with the direction I have been pursuing with the 6J9P.
I have switched to a cascode front end so have not yet tried this change, however it is consistent with the direction I have been pursuing with the 6J9P.
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Hi Piano,
I actually did try 20uF with several high quality caps in parallel (0.1uF etc) and it did not work very well sonically. There was quite an audible suck out in the mid range - possibly something in the range of a couple of uF in parallel might have worked.
I actually did try 20uF with several high quality caps in parallel (0.1uF etc) and it did not work very well sonically. There was quite an audible suck out in the mid range - possibly something in the range of a couple of uF in parallel might have worked.
Hi,
Something we did back in the Eighties when a relatively large film cap (say 5 microF) was required is split it up as follows:
4.7 microF + .47 microF + .047 microF etc. (10% rule). The smallest values could then be polysterenes for example.
If I'm not mistaken the MIT Relcaps are built in a similar way?
Teflon caps were definitely out of reach in those days...
Ciao, 😉
Something we did back in the Eighties when a relatively large film cap (say 5 microF) was required is split it up as follows:
4.7 microF + .47 microF + .047 microF etc. (10% rule). The smallest values could then be polysterenes for example.
If I'm not mistaken the MIT Relcaps are built in a similar way?
Teflon caps were definitely out of reach in those days...
Ciao, 😉
Midrange? Goodness! That's difficult to understand since there should be little voltage across the cap; some sort of resonant behaviour do you think?
Hi Frank, Piano,
Yes the Rel (now Audio Cap) are sectioned usually into 10 equal sections except in the case of a few cheaper ones. (TFT and RTX 10, RT 2 IIRC)
I used to parallel caps a decade apart in value, and tried something similar with the 20uF cap.. Haven't found it necessary in a long time to do this except with large caps of course. (Did it in the GM70 amps for some large bypass caps - worked fine there)
I suspect a resonance as well piano..
Yes the Rel (now Audio Cap) are sectioned usually into 10 equal sections except in the case of a few cheaper ones. (TFT and RTX 10, RT 2 IIRC)
I used to parallel caps a decade apart in value, and tried something similar with the 20uF cap.. Haven't found it necessary in a long time to do this except with large caps of course. (Did it in the GM70 amps for some large bypass caps - worked fine there)
I suspect a resonance as well piano..
Hi Kevin,
From looking at the base diagram of the penthode it seems the suppressor grid is not connected internally but is led out to pin 8 (IIRC).
Did you just connect it to the cathode?
If so, and you have a spare film cap of a few 100nF, do you mind trying to connect pin 8 to cathode through the cap a la Decware or is this nonsense?
Just curious about the effect if any, that's all.
Ciao, 😉
From looking at the base diagram of the penthode it seems the suppressor grid is not connected internally but is led out to pin 8 (IIRC).
Did you just connect it to the cathode?
If so, and you have a spare film cap of a few 100nF, do you mind trying to connect pin 8 to cathode through the cap a la Decware or is this nonsense?
Just curious about the effect if any, that's all.
Ciao, 😉
Hi Frank,
It was directly connected to ground rather than the cathode, and unfortunately I rewired the pre-amp to use the 6N14P so I'm not able to further experiment at this point in time.
It was directly connected to ground rather than the cathode, and unfortunately I rewired the pre-amp to use the 6N14P so I'm not able to further experiment at this point in time.
End Note...
My final take on this design would be to say that it ultimately evolved into the cascode input stage Muscovite Mini II using the 6N14P which is a much better sounding design frankly. While I doubt anyone has built one of these yet I would very strongly recommend building the cascode version instead of this one.
http://www.diyaudio.com/forums/analogue-source/254641-muscovite-mini-ii-6n14p-phono-stage.html
The good news is the conversion took me under 30 minutes to complete and eliminates the problematic screen bypass cap issue completely. The 6N14P is extremely inexpensive at this juncture and the ECC84 will work quite well also.
My final take on this design would be to say that it ultimately evolved into the cascode input stage Muscovite Mini II using the 6N14P which is a much better sounding design frankly. While I doubt anyone has built one of these yet I would very strongly recommend building the cascode version instead of this one.
http://www.diyaudio.com/forums/analogue-source/254641-muscovite-mini-ii-6n14p-phono-stage.html
The good news is the conversion took me under 30 minutes to complete and eliminates the problematic screen bypass cap issue completely. The 6N14P is extremely inexpensive at this juncture and the ECC84 will work quite well also.
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