I have little experience with tube amps (built 1 spud) and have 8 Russian 6n6p tubes. Im building a preamp and would like to use the tubes as a buffer for the output to lower the impedance after the pot.
Is there a simple schematic someone has for this using a cathode buffer with 1 tube? Im in the USA so I was thinking of just getting 2 6.3vac transformers and running 1 to the wall to step down to 6.3, then connect the other one to step it back to 120vac and use a full bridge rec to convert to 170vdc.
Can i just copy Lamps version that he uses for his dac's?
Is there a simple schematic someone has for this using a cathode buffer with 1 tube? Im in the USA so I was thinking of just getting 2 6.3vac transformers and running 1 to the wall to step down to 6.3, then connect the other one to step it back to 120vac and use a full bridge rec to convert to 170vdc.
Can i just copy Lamps version that he uses for his dac's?
Consider the DC coupled follower designed and documented by forum member SY. It's called Heretic: http://www.diyaudio.com/forums/tubes-valves/58757-heretical-unity-gain-line-stage.html
You mean this? Preamplifier_with_HEAD
You can adapt it, but the performance may be mediocre.
While undoubtedly sound, SY's design is anything but simple and could be a trap for a builder with little experience.
FWIW, I suggest 10M45S constant current sink loaded cathode followers and a bipolar PSU. That sort of arrangement places only 1 cap., at the unit's O/P, in the signal path. A 4.7 μF metalized polypropylene part bypassed by a 470 nF. 716P series Orange Drop does that job well, without spending a lot.
A $25 AnTek model AN-05T160 power trafo looks like a reasonable fit for the job. To get a bipolar supply, each rail would be 1/2 wave rectified, but making the 1st filter caps. big deals with that matter. A single filter choke can be shared between the 2 rails, in the grounded leg. A pair of 600 PIV Schottky diodes for rectification are inexpensive enough and yield "noiseless" operation.
FWIW, I suggest 10M45S constant current sink loaded cathode followers and a bipolar PSU. That sort of arrangement places only 1 cap., at the unit's O/P, in the signal path. A 4.7 μF metalized polypropylene part bypassed by a 470 nF. 716P series Orange Drop does that job well, without spending a lot.
A $25 AnTek model AN-05T160 power trafo looks like a reasonable fit for the job. To get a bipolar supply, each rail would be 1/2 wave rectified, but making the 1st filter caps. big deals with that matter. A single filter choke can be shared between the 2 rails, in the grounded leg. A pair of 600 PIV Schottky diodes for rectification are inexpensive enough and yield "noiseless" operation.
Oh man Eli is following me again. Um with a BP supply i halve my voltage so supply caps would be alot cheaper. Any schematics or something to go on? Since im a beginer i cant make anything from scratch. I just wanted to get some tube sound to my Tamp and 3886 amp i built up.
Heres what i was going to adapt.
http://www.lampizator.eu/lampizator/LAMPUCERA/MAX/IMG_5144.jpg
its got 2 caps in the audio path, but the first can be small so i can get something nice. The output cap might set me back alittle if i go full metal film.
Heres what i was going to adapt.
http://www.lampizator.eu/lampizator/LAMPUCERA/MAX/IMG_5144.jpg
its got 2 caps in the audio path, but the first can be small so i can get something nice. The output cap might set me back alittle if i go full metal film.
Nightanole, But that's not a cathode follower, it's an anode follower. However, with the lowish plate impedance of the 6n6, you may not need a cathode follower. I use a 6n6 preamp and take the output from the plate, no problem.
see this, but it has to change for 6n6p, that and a very good blog 10000 circuits...
http://circuitoseletronics.blogspot.com/2010/06/simple-cathode-follower.html
Moderator Warning Note:
the link does take you to a cathode follower, but also opens new windows for at string of advertisements
http://circuitoseletronics.blogspot.com/2010/06/simple-cathode-follower.html
Moderator Warning Note:
the link does take you to a cathode follower, but also opens new windows for at string of advertisementsSorry wrong lamp
http://www.lampizator.eu/LAMPIZATOR/LAMPUCERA/MAX/IMG_5143.jpg
heres the cathode version
http://www.lampizator.eu/LAMPIZATOR/LAMPUCERA/MAX/IMG_5143.jpg
heres the cathode version
Nope, it is a cathode follower. A very bad one, with 330 ohm cathode resistors hahaha!
The second schematic is indeed a stunningly incompetent cathode follower "design." The first one is an extremely questionable common cathode amplifier.
Do people actually BUILD this stuff???? (shakes head sadly)
What is questionable about he 2nd schematic? it looks pretty white to me. If the only problems are the values for RG and RK can i just switch them?
Maarten's tube spread sheet uses default values of rk= 10k and Rg= 470k. I popped in lamps values and it just attenuated it to .77 gain out instead of white .95.
Maarten's tube spread sheet uses default values of rk= 10k and Rg= 470k. I popped in lamps values and it just attenuated it to .77 gain out instead of white .95.
http://img710.imageshack.us/img710/8649/6n6p.jpg
Ignoring the 230v in, would this work?
I have an unused socket and 8 6n6p new tubes i got for 8 bucks. id like to use them vs $50 set of matched something or anothers, or worse case if it gets too complicated, a standard SS design. I just thought a tube buffer would be fun. So far i cant find a unity gain design that doesnt use tubes that cost more then the amp parts less transformer.
Ignoring the 230v in, would this work?
I have an unused socket and 8 6n6p new tubes i got for 8 bucks. id like to use them vs $50 set of matched something or anothers, or worse case if it gets too complicated, a standard SS design. I just thought a tube buffer would be fun. So far i cant find a unity gain design that doesnt use tubes that cost more then the amp parts less transformer.
Another stunningly bad circuit.
Not to self-promote, but it would be worthwhile to read through my treatment of cathode follower design. You might not want to use the specific circuits I call out, but at least you can see some examples of properly designed circuits.
SYclotron Audio The Heretical Preamp
Not to self-promote, but it would be worthwhile to read through my treatment of cathode follower design. You might not want to use the specific circuits I call out, but at least you can see some examples of properly designed circuits.
SYclotron Audio The Heretical Preamp
worst circuit ever!
I throw 10VPP PSR (120Hz) and 10VPP CMR (450Hz)
at it just to demonstrate how heinously awful bad...
Don't try to understand it, you waste your time.
I throw 10VPP PSR (120Hz) and 10VPP CMR (450Hz)
at it just to demonstrate how heinously awful bad...
Don't try to understand it, you waste your time.
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UH...
So guys do we have a tube buffer that anyone likes that doesnt require alot of parts or rare expensive matched tubes?
I understand Sy's preamp up until the holly crap 12v sections, and the fact it requires 8uf input/output caps to be happy. That means electrolytics for me maybe bypassed with a box cap for all my sources, no more MKP's in the bamtam dac.
So guys do we have a tube buffer that anyone likes that doesnt require alot of parts or rare expensive matched tubes?
I understand Sy's preamp up until the holly crap 12v sections, and the fact it requires 8uf input/output caps to be happy. That means electrolytics for me maybe bypassed with a box cap for all my sources, no more MKP's in the bamtam dac.
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My circuit is indeed somewhat complex, but there's no 8u input caps! Output caps can be sized depending on the impedance of the load and the desired f3.
Here's a very simple buffer that will run rings around the circuits you've been putting up. I show a 2u output cap, but again, use f3 = 1/(2piRC) to calculate how big the cap really needs to be. For a 100k load, 1u should be sufficient.
I didn't have a crossover symbol, so imagine that the 1u bypass cap goes from the plate to the far end of the cathode resistor (connection to ground). The 1k grid stopper resistor should be right at the grid pin of the tube. Tube can be any of the ECC88 family. Matching is unnecessary.
Bias up the heaters 50V or so above ground to avoid stressing the heater to cathode insulation. The cathode will be ~100V or so above ground.
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