Replace the 2nd triode with a 6DJ8 or 6N23P for even lower output impedance!
Don't bother with positive feedback.
I've done a few CCDA type of builds, they work very well. I've even done one with a negative rail, and used the DC servo from Sy's heretical preamp for the output. Use the negative rail for the common on the input tube, but reference the cathode follower to ground. Worked very well. CCS or gyrator load the input tube if you want to get fancy.
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My tube pre goes into a class D board with 26k impedance, so I am not sure if I need a lower output impedance. I am however, open to tweaking the circuit to further improve sound if possible and I am thinking about converting it to the one with grid resistors input. I need to study the CCS or gyrator part before attempting those as I am quite new to tubes and circuits.
BTW, for 6sn7 I am using the Psvane cv181 mk2. The Prsvane is my preference after comparing 3 "premium priced" equivalent Osram B65, Mullard ECC32, and RCA 5962 (borrowed from a friend , price on ebay is very high). And I really like the sound from 6sn7 tube after trying other smaller tubes like 5670, 6n1p/6n3p (those in a different circuit however).
Why would you need 6SN7 if 6P15P is itself extremely linear tube designed for video amplifiers?
Just wondering 6p15p being more linear will translates to better sounding than 6sn7? Also, can I simply convert the pins and plugin the 6p15p to replace 6sn7?
6SN7 should be able to drive 26k at these levels just fine in this application. If you were feeding into 10k I would do the 6DJ8 or similar, but it should work well for you. Don't be afraid to run a bit higher current through the 6SN7 though, it will work great at higher dissipation within proper design specs.
Don't get me started on "Psvane" or "premium" type tubes
I don't bother with any audiophile grade tubes, as they rarely measure any better and often aren't true to original specsheets. My "6SN7" of choice is the Russian "6H8C" as it measures well, and is often just a few dollars a piece.
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Thank you! I've been saying this about most Soviet tubes.
FYI I run 400V on the plates of these, most of them can handle 6SN7GTB service even if they aren't rated for it.
I'm also running 6P1P tubes at 18W dissipation without any glow or issue
To that end you don't have to stick to the ol' 6.3v 6SN7. That tube has brothers, both octal and loctal, that can be found NOS for under $10, sometime well under $10
$2.20 each aint bad, even cheaper if you buy in bulk on eBay
6N8S = 6SN7 = ECC32 = 6CC10 tube. Double triode ? Hi-End vacuum tubes, sockets, capacitors, nixie. Retail and wholesale to worldwide.
I'm always on the lookout for cheap linear tubes though, and for that it's hard to beat many of the surplus russian stuff...
Hello everyone.
Thank you all for reply. I think, I'll make something like kodabmx suggested. When I finish the scheme I'll post it here. Both with power supply scheme.
I am going to buy a new (old) Philips CD player with tda DAC chip, so maybe I'll try to connect the preamp to DAC output to check, how "lampizator" mod works using 6n23p in NOS mode...
Thank you all for reply. I think, I'll make something like kodabmx suggested. When I finish the scheme I'll post it here. Both with power supply scheme.
I am going to buy a new (old) Philips CD player with tda DAC chip, so maybe I'll try to connect the preamp to DAC output to check, how "lampizator" mod works using 6n23p in NOS mode...
Hi,
6sn7, 6h23n and 6n1 that you made, which sound is the best? with 6h23n I already made with j5 and capacitors, the sound results are quite good, very good.
Thanks.
As long as the part values are chosen well, and the thing isn't overdriven, I don't notice much of a difference. If you only have 150V-200V, use a 6DJ8/6N32P or the 6N24P which is close enough but with a different pinout. If you only have 24V-50V, use a 6N27P. If you have 250V-300V, use 6N1P or 6N8S (6SN7).
Generally though, if I use the CCDA, I use 6N8S octal tubes for it with a 280V supply (because I have 280V on hand).
Generally though, if I use the CCDA, I use 6N8S octal tubes for it with a 280V supply (because I have 280V on hand).
agree @kodabmx.
very interested in what you have done and really appreciate the information you have shared. did you apply the resistor according to the rules mr. broskie on each type of tube. or just plug and play by applying a change in voltage b +. i got data of resistor values for each type of tube from mr.broskie's manual.
sorry I am poor in English.
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thank you,
a beautiful long journey and worth to trying. so far I have tried to compare between 6n23 and 6dj8 reissue. I got 6n23 still the best for me to enjoy the sound. [at least to my ears] in the direction of 6n3p I don't yet have. I am interested in 6n5p which is claimed to be identical to 6dj / 6n1p, but unfortunately there isn't much to review about that type. is there anyone here who tried it ?.
I will try it soon. I am interested in the triple mica design on 6n5p, my friend's info will be better sound quality. Hopefully ... now my ears enjoying the first with 6n23p.
Happy New Year 2020. Hope, lucky always with you.
I really like this circuit. Constant current draw, very low distortion, low output impedance.
mine used a 120vdc rail, 6.8k plate and cathode resistors, 82 ohm common cathode resistor un bypassed....really liked it...the cathode follower resistor not connected to the common cathode resistor...i made and sold lots of these, even better liked than the aikido...
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