Apologies first, if I am already repeating a topic covered in other threads.
I have suspended my Mini -A building project for a while because I couldn’t get it playing properly for some strange reasons and I still have couple of IRFP240 fets left. So I thought, that Andrea Ciuffoly’s Power Follower 99 could be an easy enough design to experiment with those devices. Being a fet follower it needs high gain and low output impedance voltage source. I have couple of Russian NOS 6N1P (close to 6DJ8/ECC88) and 6N2P (12AX7/ECC83 Russian version) laying around and tubes line stage becomes an attractive choice. I would prefer only one tube (that is two envelopes) per channel. But a question remains which configuration to build to meet the high gain /low Zout specs.
At first I thought about SRPP because of its simplicity but it looks like that with these mentioned tubes Zout will always be highish.
Another option could be Grounded Cathode followed with Cathode Follower, either using same type of tube or two different types for one channel. But I have read somewhere that cathode followers can sound not so good if designed sloppily. Having very little experience with tubes to design my own tube preamp, I have been looking and searching around for suitable circuit using these tubes but I haven’t found any.
Can anybody point out some or make related suggestions?
Argo
I have suspended my Mini -A building project for a while because I couldn’t get it playing properly for some strange reasons and I still have couple of IRFP240 fets left. So I thought, that Andrea Ciuffoly’s Power Follower 99 could be an easy enough design to experiment with those devices. Being a fet follower it needs high gain and low output impedance voltage source. I have couple of Russian NOS 6N1P (close to 6DJ8/ECC88) and 6N2P (12AX7/ECC83 Russian version) laying around and tubes line stage becomes an attractive choice. I would prefer only one tube (that is two envelopes) per channel. But a question remains which configuration to build to meet the high gain /low Zout specs.
At first I thought about SRPP because of its simplicity but it looks like that with these mentioned tubes Zout will always be highish.
Another option could be Grounded Cathode followed with Cathode Follower, either using same type of tube or two different types for one channel. But I have read somewhere that cathode followers can sound not so good if designed sloppily. Having very little experience with tubes to design my own tube preamp, I have been looking and searching around for suitable circuit using these tubes but I haven’t found any.
Can anybody point out some or make related suggestions?
Argo
Hello,
I am in the same situation, but with phillips e88cc tubes, and the amp is an Aleph 60.
This topic has been discussed in "Tube line-buffer for cd" thread.
I think that you can make a fairly low impedance SRPP with ecc88, (Zout ~ 800 ohm, gain ~ 25). The only problem with the SRPP is that you have to optimize it for the required load. (read at www.tubecad.com/articles_2002/SRPP_Deconstructed/page28.html)
The another way should be the White Cathode-Follower.
So, we are expecting some info from tube-guru's
thanks and regards,
Miki.
I am in the same situation, but with phillips e88cc tubes, and the amp is an Aleph 60.
This topic has been discussed in "Tube line-buffer for cd" thread.
I think that you can make a fairly low impedance SRPP with ecc88, (Zout ~ 800 ohm, gain ~ 25). The only problem with the SRPP is that you have to optimize it for the required load. (read at www.tubecad.com/articles_2002/SRPP_Deconstructed/page28.html)
The another way should be the White Cathode-Follower.
So, we are expecting some info from tube-guru's
thanks and regards,
Miki.
jeff mai said:
Yes this could be an option but I'd like to keep it without transformator first cause I don’t have one and would preferably use components I already have now in my junkbox: those mentioned tubes, caps, resistors.
Miki
thanks for the link – I have read some articles about SRPP but have missed this one.
Any cathode follower designs?
Argo
Argo,
With the tubes you have, and no desire to use an output transformer (best option IMO), SRPP with the 6N1P is probably the best option. However, the 6N1P is <b>not</b> a near 6DJ8 substitute (6H23 is) and will give a higher output Z then the 6DJ8, by a factor of at least 2, probably 3. Anyway, it will still work better than a 12AX7 in this application.
Cheers
With the tubes you have, and no desire to use an output transformer (best option IMO), SRPP with the 6N1P is probably the best option. However, the 6N1P is <b>not</b> a near 6DJ8 substitute (6H23 is) and will give a higher output Z then the 6DJ8, by a factor of at least 2, probably 3. Anyway, it will still work better than a 12AX7 in this application.
Cheers
Re: design process
and does your riddle have any answers?
Argo
almarcy said:design is not just solving riddles. it requires you to build and listen and think.
abandon hope, all ye who enter here
there is more to learn than we have time for. enjoy your visit to each circuit and keep awe as your friend.
happy ears!
al
and does your riddle have any answers?
Argo
Hi,
Got the same problem with a Zen V4. I have an EF86 based pre (triode mode, 1 stage, no cathode caps) and when I connected it to the Zen the sound was nice but it was too low. With 25W the Zen should play quite loud (I have a Rotel with 25W so can compare). First I tough I had an earthing problem, but now I believe that it is needed some impedance matching. Maybe I had a second gain stage to that pre.
Got the same problem with a Zen V4. I have an EF86 based pre (triode mode, 1 stage, no cathode caps) and when I connected it to the Zen the sound was nice but it was too low. With 25W the Zen should play quite loud (I have a Rotel with 25W so can compare). First I tough I had an earthing problem, but now I believe that it is needed some impedance matching. Maybe I had a second gain stage to that pre.
white cathode follower
The white cathode follower is the direction you should go.
See this link for a 6n1p ckt. http://headwize2.powerpill.org/projects/showproj.php?file=bender_prj.htm
If you really want to drive a load with no output transformer then the 6as7/6080 is the way to go. These can drive 600 ohm directly.
be ready to use the sand resistors in this project if you want big current drive.
AHHH yes the sound of a hundred milliamps sinking through a low mu triode --Nothin' beats it!!!
Robert Morin
My 6as7 srpp still sounds GREAT Who needs 2a3, 300b, 45......
The white cathode follower is the direction you should go.
See this link for a 6n1p ckt. http://headwize2.powerpill.org/projects/showproj.php?file=bender_prj.htm
If you really want to drive a load with no output transformer then the 6as7/6080 is the way to go. These can drive 600 ohm directly.
be ready to use the sand resistors in this project if you want big current drive.
AHHH yes the sound of a hundred milliamps sinking through a low mu triode --Nothin' beats it!!!
Robert Morin
My 6as7 srpp still sounds GREAT Who needs 2a3, 300b, 45......
Re: design process
Thank you for reminding me.
Bowing Deeply
Brett
Al-san,almarcy said:design is not just solving riddles. it requires you to build and listen and think.
abandon hope, all ye who enter here
there is more to learn than we have time for. enjoy your visit to each circuit and keep awe as your friend.
happy ears!
al
Thank you for reminding me.
Bowing Deeply
Brett
Joel said:
And you should really read the original post carefully before you post. I asked schematic or suggestion for using those specific tubes (6N1P, 6N2P) because I can draw up a schematic and calculate the resistor values but not having experience with these tubes I doubted that I can get good result doing it by my own. So I asked if somebody have a proven schematic for these tubes or experience with cathode followers. I am sorry if I was not clear enough and if I possibly repeated the question already answered elsewhere in this board.
Argo
dodonoid said:Hi, Argo.
A WCF schematic is what I am waiting for, too
Until then I will make an SRPP with e88cc (Phillips), i will use it in the front of an Aleph60 (~ 47k input impedance), and try to optimize for this load.
Once it's finished, I will post the results.
Bye,
Miki.
Miki
While we are waiting fore some more experienced tweekers to contribute, I draw up a schematic with cathode follower using 6dj8/ecc88/6922 tubes you have. I think this one should work. How does it sound I have no clue. As for SRPP using B+ around 150V and Rk=Rak=150 ohm should also work. Or better jet, put a 500 ohm potentiometers in series with Rk=Rak =100 ohm resistors and try to find optimal value while listening.
Argo
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