So thats as simple as slapping the meter on the secondary of the transformer?
I can't do much more today, but tomorrow I will do more fiddling around when I get home. What kind of power ratings will I need for the power supply's resistors? Most of the schematics I've seen use 1W to 5W resistors. Can Spice tell me what kind of power the resistors need to handle somehow?
I can't do much more today, but tomorrow I will do more fiddling around when I get home. What kind of power ratings will I need for the power supply's resistors? Most of the schematics I've seen use 1W to 5W resistors. Can Spice tell me what kind of power the resistors need to handle somehow?
I read the help file on .op mode, but I'm not sure how to get the readings I want. I tried graphing the voltage and current of each resistor and multiplying the peak values together, but I would need like a 30W resistor for one of them. Seems way too high to me.
Could you please take a look and see what I'm doing wrong?
Could you please take a look and see what I'm doing wrong?
I need to add my bit
, I have built just about every line stage topology possible, well, enough to make an informed decision, and imo, the simpler, the better.
as to topologies, I thought about it, and distilled it into
3 types
single valve
compound, where one valve is loaded or modified by another eg cascOde
and cascade where one valve feeds into another in series (left to right)
you can probably reduce all to one of those 3 variations
eg a bottlehead 4 play is a casCAde of 2 single stages, grounded cathode, and cathode follower.
the best 2 sounding for me was the simple single grounded cathode, and the srpp stage.
the more complex it got the more life it lost. even adding a cathode follower on the end.
proably the 2 most commercial circuits are the A-K follower, as in the bottlehead 4play, eastern minimax and many others, and the SRPP, liked in the far east
the mu just gives even more balls than the srpp.
the conrad johnson premier 8 facsimile was awful.
paralleling doesn't work, on low level and hi level stages.
even using the basic grounded cathode, there are myriads of variations to try, load resistors, or a choke instead.
check this out, it doesn't get much better, despite the theoretical concerns over zout
http://www.users.globalnet.co.uk/~valveamp/
its under the read it section on the lhs, line level preamp project
HT voltage
bias values, grid biasing
using led, zener, battery bias
component changes, eg cap quality
and myriads of psu variations, choke input.
notwithstanding lots of tubes to play with.
thence adding feedback to the grid, from the anode.
you could spend a lifetime on that one alone.
using the anode ouptut of the srpp sounded worse.
, I have built just about every line stage topology possible, well, enough to make an informed decision, and imo, the simpler, the better.
as to topologies, I thought about it, and distilled it into
3 types
single valve
compound, where one valve is loaded or modified by another eg cascOde
and cascade where one valve feeds into another in series (left to right)
you can probably reduce all to one of those 3 variations
eg a bottlehead 4 play is a casCAde of 2 single stages, grounded cathode, and cathode follower.
the best 2 sounding for me was the simple single grounded cathode, and the srpp stage.
the more complex it got the more life it lost. even adding a cathode follower on the end.
proably the 2 most commercial circuits are the A-K follower, as in the bottlehead 4play, eastern minimax and many others, and the SRPP, liked in the far east
the mu just gives even more balls than the srpp.
the conrad johnson premier 8 facsimile was awful.
paralleling doesn't work, on low level and hi level stages.
even using the basic grounded cathode, there are myriads of variations to try, load resistors, or a choke instead.
check this out, it doesn't get much better, despite the theoretical concerns over zout
http://www.users.globalnet.co.uk/~valveamp/
its under the read it section on the lhs, line level preamp project
HT voltage
bias values, grid biasing
using led, zener, battery bias
component changes, eg cap quality
and myriads of psu variations, choke input.
notwithstanding lots of tubes to play with.
thence adding feedback to the grid, from the anode.
you could spend a lifetime on that one alone.
using the anode ouptut of the srpp sounded worse.
Tomorrow I'm going to buy some 3W 1k resistors (if I can find them) at the store, the simulating and experimenting I've been doing have led me to believe that these may be acceptable values to get around 280V DC out of the supply.
I tried testing the circuit with 1/2 watt resistors, including the 10k load, but they all almost smoked, so I wasn't even able to get any data from that. But if my simulations are correct then 1k resistors are what I need. Even though PSUDII and LTSpice gave different answers for the same circuit.
I tried testing the circuit with 1/2 watt resistors, including the 10k load, but they all almost smoked, so I wasn't even able to get any data from that. But if my simulations are correct then 1k resistors are what I need. Even though PSUDII and LTSpice gave different answers for the same circuit.
This is not completely true. I use it as a very handy and very serious tool. It is much easier to do everything related to the power supply with the PSUD2 than simulating everything with a Spice simulator. Furthermore, since you just have to input some important data, there is less chance that you will be wrong.
A long time ago, I used Protel... only to find out that it is much simpler and faster and more efficient to use a smaller program to do the same job. This obviously applies to PSUD2 vs Spice simulators. When designing a complex circuit like a PC motherboard, you will not be able to do it in some simple and efficient program... but Protel would probably be a good choice. Vice versa, a preamplifier is a simple circuit and there is no reason to bother with the whole Protel package.
The same is true of PSUD2 vs Spice simulators... and I am writing this only because you and some other people seem to be learning something on the forums. I guess you should have a dose of common sense in your teaching
Okay,
I completed one channel of the amp roughly, to see if things even work before I make it tidy and small enough to fit in the box. The tube heaters come on, but the voltage on the anode in relation to the power supply negative is 380V. This is the same voltage as the power supply when its unloaded. However, when I put a 3W 12k resistor on the PSU, it drops to a nice 290V. I'm not sure why this is happening, but could it have something to do with these 1/4 watt 1% resistors I used in the preamp circuit? 1/4 was the only power rating that the store had for 1% precision resistors. The amp was at minimum volume when I tested.
I'm sure I did something wrong, but there was no smoke or fire and my tube didn't do anything other than glow peacefully.
I completed one channel of the amp roughly, to see if things even work before I make it tidy and small enough to fit in the box. The tube heaters come on, but the voltage on the anode in relation to the power supply negative is 380V. This is the same voltage as the power supply when its unloaded. However, when I put a 3W 12k resistor on the PSU, it drops to a nice 290V. I'm not sure why this is happening, but could it have something to do with these 1/4 watt 1% resistors I used in the preamp circuit? 1/4 was the only power rating that the store had for 1% precision resistors. The amp was at minimum volume when I tested.
I'm sure I did something wrong, but there was no smoke or fire and my tube didn't do anything other than glow peacefully.
Okay, I turned the preamp on, and through my 12k resistor the voltage was ~0V for about 10 seconds, then the voltage increased to about 164V over the course of 10 seconds or so.
I then measured the voltage on the anode, which started out at 383V and dropped to 150V in the same timeframe as the 12k resistor.
So, the tube is biasing? I believe, except the voltage drop at the 12k resistor is far too high. I'm thinking a lower value there is what I need? Also, is that initial voltage peak of 383V okay for the tube or is that damaging, both short and long term?
I then measured the voltage on the anode, which started out at 383V and dropped to 150V in the same timeframe as the 12k resistor.
So, the tube is biasing? I believe, except the voltage drop at the 12k resistor is far too high. I'm thinking a lower value there is what I need? Also, is that initial voltage peak of 383V okay for the tube or is that damaging, both short and long term?
Dont mind the high initial voltage. This happens in all unregulated supplies. But you could add a bleeder resistor that keeps initial voltage closer to 300V if you are worried .
But it seems to be something wrong with the amp circuit as it draws very much current. Do not change the anode resistor. Change the cathode resistor to a higher value i fnecesarry. You should have ca 150 at the anode with reference to ground.
But it seems to be something wrong with the amp circuit as it draws very much current. Do not change the anode resistor. Change the cathode resistor to a higher value i fnecesarry. You should have ca 150 at the anode with reference to ground.
http://classicvalve.ca/tubepcb.html#UNI
CK-7 and CK-26 pcb will be useful to make simple line preamp using 12AU7 or other tubes.
CK-7 and CK-26 pcb will be useful to make simple line preamp using 12AU7 or other tubes.
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