I have picked up a Behringer SRC2496 after reading some positive stories online. It sounds horrible stock, but I am planning to build an SRPP output stage using subminiature tubes (6N16). Datasheet here: audio.ring.lt/pdf/6n16b.pdf
Since this is my first tube project, I would like to run the setup by some more experienced people.
SRPP
B+ at 100V
Rk = 333 Ohm
Ra = 16k6 Ohm
R to ground = 300 Ohm
I still have some trouble designing the PSU, esp. wrt to the load resistance of the tube circuit.
Thanks for the help!
Since this is my first tube project, I would like to run the setup by some more experienced people.
SRPP
B+ at 100V
Rk = 333 Ohm
Ra = 16k6 Ohm
R to ground = 300 Ohm
I still have some trouble designing the PSU, esp. wrt to the load resistance of the tube circuit.
Thanks for the help!
Should be in the tube section. SRPP output is non-ideal in a lot of applications, more of a fashion statement really. I have used it extensively and like it, but arguably not suited to general application - you need to design it to drive a well defined load impedance for optimum performance.
Also your proposed plate voltage is probably too low in an SRPP.
Incidentally not all tubes are universally applicable to SRPP application, I've found quite a few that frankly do not work, and also do not assume that you are going to realize a particularly low source impedance depending on the choice of tube. High perveance, high transconductance types seem to work pretty well..
Unless you need gain a CCS loaded cathode follower might be a better choice.
Make sure you can get the 6N16P before you plan extensively.. Some exotic Soviet subminiature types are not always easy to procure.
Also your proposed plate voltage is probably too low in an SRPP.
Incidentally not all tubes are universally applicable to SRPP application, I've found quite a few that frankly do not work, and also do not assume that you are going to realize a particularly low source impedance depending on the choice of tube. High perveance, high transconductance types seem to work pretty well..
Unless you need gain a CCS loaded cathode follower might be a better choice.
Make sure you can get the 6N16P before you plan extensively.. Some exotic Soviet subminiature types are not always easy to procure.
Moved to "Tubes."Read it, re-read it, and read-it again. Extremely helpful site for a beginner like myself
I have a 125VAC transformer lying around, so my PSU (CLC) would give a B+ of 176VDC.
This leaves each tube 88V. If I understand the datasheet of the 6n16 well (audio.ring.lt/pdf/6n16b.pdf), this leaves and operating point of 88V/3.6mA, which is on the -2V line.
I am still a bit puzzled on how to calculate the resistor values in SRPP.
Rk = -2V / 0.0036 = 555 Ohm ?
The R between the top and bottom tube should be the same as Rk?
Noted. Let's take this as a first attempt at doing a tube project. The best description on the web seems to be the Lampizator site, so I'd prefer to take this as a starting point and further develop my skills from there.
Thanks
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Allright, so Mr. Lampizator is a bit of a controversial character.
But that still leaves me with my resistor uncertainty ...
Your previous post on the resistor issue was on the right track, I would try 560 ohm resistors in both locations and see how close you get to your target current.. Your supply voltage should be adequate as long as it doesn't fall too far below 80V per triode. Some tweaking of the resistor value up or down is potentially necessary, but if you come within 10% or so of your target current that should be fine.
And so I went off and built the Lampizator output stage with 6N16 subminiature tubes...
Now I've built it, but sound is distorted and gain wayyy too high (can't get the volume pot on my amp past 8 o'clock).
After building a CRC PSU, with a 10k bleeder resistor, the B+ is 155VDC. According to the datasheet, this matches 2.3mA current, so both cathode resistors are 2/0.0023 = 869 Ohm (nearest I could find it 820 Ohm).
I used the schematic on this page (SRPP): Mikrolampizator
How can I set a lower gain? and lower distortion?
Now I've built it, but sound is distorted and gain wayyy too high (can't get the volume pot on my amp past 8 o'clock).
After building a CRC PSU, with a 10k bleeder resistor, the B+ is 155VDC. According to the datasheet, this matches 2.3mA current, so both cathode resistors are 2/0.0023 = 869 Ohm (nearest I could find it 820 Ohm).
I used the schematic on this page (SRPP): Mikrolampizator
How can I set a lower gain? and lower distortion?
Use 1k2 Rk and Ra.
1M grid to ground resistor and 47uF cathode bypass.
Thats what I use and get a very good clean sound.
I use an SRPP front end in my hybrid amplifiers.
I use an ECC82.
The gain in my SRPP seems to be about the same as the mu of the valve.
This entire thread is pointless without ALL the kley details that are missing, namely what the output load is (?!?), what the input looks like and what you want to achieve. Any reply you receive will be limited to constraints you made in your initial post and probably far from an optimal solution.
The way I understand it you want to run SRPP into a variable load (300R headphones ?) with low B+. That's about as silly as riding a monocycle with square wheel up some strairs and optimizing the rubber mixture of your square tire to get a smoother ride. This is a bad idea and a waste of resources.
Instead, please tell us what you want to do and what it is that you want to do, what is the laod, what is the required amplification factor, etc. - this way you'll get the best possible advice from people here
The way I understand it you want to run SRPP into a variable load (300R headphones ?) with low B+. That's about as silly as riding a monocycle with square wheel up some strairs and optimizing the rubber mixture of your square tire to get a smoother ride. This is a bad idea and a waste of resources.
Instead, please tell us what you want to do and what it is that you want to do, what is the laod, what is the required amplification factor, etc. - this way you'll get the best possible advice from people here
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Since tubes are high Z input transconductance devices the most relevant parameters are:
1: input voltage swing (tube presents minimal load to the input stage, which is always determined by grid resistor rather than actual input resistance)
2: output load
3: optional, but very useful: desired voltage gain
4: optional, but very useful: description of what you're trying to achieve (sound coloration, actual voltage gain, buffering, ...)
If you don't have acess to schematic of your amplifier, you definitely should measure its input resistance. SRPP needs known and fixed impedance to work optimally into (check out Broskie's website for good elaboration on this: John Broskie's Guide to Tube Circuit Analysis & Design ).
1: input voltage swing (tube presents minimal load to the input stage, which is always determined by grid resistor rather than actual input resistance)
2: output load
3: optional, but very useful: desired voltage gain
4: optional, but very useful: description of what you're trying to achieve (sound coloration, actual voltage gain, buffering, ...)
If you don't have acess to schematic of your amplifier, you definitely should measure its input resistance. SRPP needs known and fixed impedance to work optimally into (check out Broskie's website for good elaboration on this: John Broskie's Guide to Tube Circuit Analysis & Design ).
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