Adam,
I think you are suffering from analysis paralysis. You are most likely fair new to building, am I right? I think it is much more important to build one of later circuits in these pages, doesn't matter which really and when it is working then you can worry about tweaking, and trying other ideas out. There is no real "best", some may be slightly better than others, but all should be exceptionally good.
I think you are suffering from analysis paralysis. You are most likely fair new to building, am I right? I think it is much more important to build one of later circuits in these pages, doesn't matter which really and when it is working then you can worry about tweaking, and trying other ideas out. There is no real "best", some may be slightly better than others, but all should be exceptionally good.
I agree with JoshK. I'm building a "Basic" 12B4 preamp based on an old audio express article in the while I figure out how I'm going to do the casework for one of the designs in this thread.
This one just has a cathode resistor rather than the LM317, uses a voltage doubler, and runs off a wallwart with back-to-back transformers
. You can always do tweaks to the design once you have something built.
This one just has a cathode resistor rather than the LM317, uses a voltage doubler, and runs off a wallwart with back-to-back transformers
. You can always do tweaks to the design once you have something built.Here's mine which I shared to another member. My operating conditions are different from most you have seen here- I'm on the low voltage, low current side. You can start with this and tweak as you like. However, this *is* my sonic preference. Since I have a really small chassis (see my post several pages back, it's a stainless chassis), I
m using MOSFET regulation. Again, this *is* my choice.
m using MOSFET regulation. Again, this *is* my choice.
Attachments
Here's a summary (kind of...).
For the tube circuit itself:
1) Anode/plate: you want to decide if you want to use plate chokes or resistors. Once that is decided, you will know what voltage to have on the PSU, generally about 150V for chokes, or 300V for resistors.
2) Cathode: Various options here, but interchangeable and relatively cheap to experiment.
a) resistor: simplest, and goes with or without bypass capacitor.
b) LM317 CCS: Requires a bypass cap
c) LEDs: yes another not too conplicated option
For the PSU:
1) Simple CLC or LC or CRC have been shown on the thread, simplest to implement.
2) Tube VR: require some extra current from PSU and calculation for the tube VR current. 300/150V is conveniently obtained via 1 or 2 0D3 or VR150 tubes which is relatively cheap too.
3) SS regulation. Kits are available, and some schematics have been shown.
Most importantly, have lots of fun!!
For the tube circuit itself:
1) Anode/plate: you want to decide if you want to use plate chokes or resistors. Once that is decided, you will know what voltage to have on the PSU, generally about 150V for chokes, or 300V for resistors.
2) Cathode: Various options here, but interchangeable and relatively cheap to experiment.
a) resistor: simplest, and goes with or without bypass capacitor.
b) LM317 CCS: Requires a bypass cap
c) LEDs: yes another not too conplicated option
For the PSU:
1) Simple CLC or LC or CRC have been shown on the thread, simplest to implement.
2) Tube VR: require some extra current from PSU and calculation for the tube VR current. 300/150V is conveniently obtained via 1 or 2 0D3 or VR150 tubes which is relatively cheap too.
3) SS regulation. Kits are available, and some schematics have been shown.
Most importantly, have lots of fun!!
Hi Adam, it's a locally made transformer, custom made to my specs.
Here's an external link for the innards -
The LM317 CCS is bypassed with 100uF Black Gate capacitor.
Here's an external link for the innards -
An externally hosted image should be here but it was not working when we last tested it.
The LM317 CCS is bypassed with 100uF Black Gate capacitor.
Hi mach1, the reason I'm running mine at 17mA is because of speed. I find it faster and snappier on my system (driving SET amps) that way. And I also noticed the smoothness on the top end, with nice touch of decay compared to a really sparkling, sometimes strident character of the 30mA operating point.
arnoldc said:
what you really need for best (with that I mean best for you,in particular system) is sometimes not achievable for common amateur ;
you need variable bench HV supply-just because you must vary both- Load resistor and current through stage (as consequence you must change biasing also and Ub - for this you need variable supply)
to define which sweet spot is yours
as Rload can be used everything in range of 1 to 10 of tube's Ri .......
so -for 12B4 something as 1 to 10K
in my experience- lower Rload demands higher Iq
I mention that to Mark somewhere in thread-but -as always-he is willing to think about my thoughts usually 3th time when I wrote them
seems that nobody tried 12B4 with,say,2K2 as Rload..........
I will not,just because I don't have any 12B4,and this toob is (was) not so common in this part of world
hehe -in any case-I'll always say that choke or-even better- OPT is better solution than resistor......
LowRedMoon said:
it's always possible,but in that case current capability of xformer is halved;
when used with CT,each half of sec conducts just half of whole periode; usually wire thickness is calculated with that in mind;
if CT is not used ,both halves are connected in series, conducting current all the time
Please excuse all of the greenhorn-style questions. Some of us are relatively new to this stuff and are prone to asking simple questions.
That said - Arnold, I'm trying to make sense of the VReg you posted (this is the first time I've looked at a SS VReg). There are two + and - points on the circuit. I'm not sure what to do with them.
Is your PS made to compliment 2 channels?
Thanks!
That said - Arnold, I'm trying to make sense of the VReg you posted (this is the first time I've looked at a SS VReg). There are two + and - points on the circuit. I'm not sure what to do with them.
Is your PS made to compliment 2 channels?
Thanks!
adam, I'm sorry for the crappy schematic... the left side is the input from the bridge rectifier. The right side is the output to serve 2 channels.
The CCS is LM317 as posted by Brian Beck. Its bypass is a Black Gate 100uF capacitor. Just compute your resistor as 1.25 / desired current, i.e., 1.25 / 17mA = 73.5 use 75ohm.
pengboon, when that picture was taken, I have the LM317 in place. The LED stack goes into the same place. In fact, right now I'm using an unbypassed 470R cathode resistor. I'm trying to pick a flavor to match my amps, and which amp (I've got three)
The CCS is LM317 as posted by Brian Beck. Its bypass is a Black Gate 100uF capacitor. Just compute your resistor as 1.25 / desired current, i.e., 1.25 / 17mA = 73.5 use 75ohm.
pengboon, when that picture was taken, I have the LM317 in place. The LED stack goes into the same place. In fact, right now I'm using an unbypassed 470R cathode resistor. I'm trying to pick a flavor to match my amps, and which amp (I've got three)