Hi Again Mr. 80 mV
under request , as usual, I send the complete list if someone is interested.
I haven't any secret. That seems others have.
Bye
Walter
under request , as usual, I send the complete list if someone is interested.
I haven't any secret. That seems others have.
Bye
Walter
I check the signals out of phase for different levels and they are very close.
The distortion at 1 kHz at 1 watt is 0,3% with only 9 dB of FB
Walter
See if you can get better balance? I would expect 0.03% @ 1W - I do use triode connection though... Perhaps pentode is just that much higher in distortion though.
In Europe we have standardized C cores and double C cores, with the latter ones having the same outer dimensions and iron cross section as an EI core of the same size. Hence, if there are end bells for some certain EI cores, they also will fit to double C cores of the same nominal size.
Best regards!
Hi Walter, I have these Sowter OPTs looking for a home, from a recent auction. They are rated at 10k Rla-a, and I have been looking for a dedicated pentode circuit to get the best from them. The type 1176s is a custom version of U063 which has a wide range (20Hz - 30Hz).
I would be interested in the list of components if you don't mind sending them to me. I like to simulate the circuits I build in LTSpice as a starting point. Also interested in a quote for the boards and delivery.to Sweden.
Rgds, Richard
I would be interested in the list of components if you don't mind sending them to me. I like to simulate the circuits I build in LTSpice as a starting point. Also interested in a quote for the boards and delivery.to Sweden.
Rgds, Richard
The current that the tube is swinging will develop a voltage across each plate and cathode load resistor- if you use a cathode bias resistor (R8) you will need to take the signal output from the junction between the bias resistor and the cathode load resistor (R8/R9 junction) or you will be introducing an error voltage into the signal from the cathode, effectively adding the bias resistor to the cathode load resistor. It will be a small error but is still an error. If the load resistors are on the order of something like 100k ohms the error will be small, if they are lower such as 22-47k ohms the error will be an order of magnitude larger.
In practice this error will end up creating primarily more 2nd harmonic distortion, which theoretically should cancel in the output stage, but it will also increase overall THD versus having equal outputs.
Best practice is to take the signal input to C5 from the R8/R9/R10 junction, and to match R11 and R10 as close as possible for perfect balance.
Hi
he list
V1= 6922-ECC88-PCC88
V2-V3 = EL84
nr. 3 noval
R1= 50 kohm ½ watt passo 5 mm
R2-R7= 470 ohm ¼ watt passo 5 mm
R3 = 27kohm 1 w passo 15 mm
R4 = 270 ohm ½ watt passo 5 mm
R5 = 68 ohm ½ watt passo 5 mm
R6 = 2k7 1 watt passo 1 5 mm
Rx = da definire ½ watt passo 4 mm
R8 = 1 Mohm ¼ watt passo 5 mm
R9 =470 ohm ½ watt passo 5 mm
R10-R11 = 18 kohm 1 watt passo 15 mm
R12-R13 = 2k2 1/watt passo 5 mm
R14-R15 = 1 kohm 1 watt passo 15 mm
R16-R17 = 1 ohm 1 watt passo 15 mm
R18-R19 = 220 kohm ½ watt passo 5 mm
R20 = 1 kohm 1 watt passo 15 mm
C1 = 0,1 uF 400 Vdc passo 20 mm
C2 = 0,1 uF 100 Vdc passo 5 mm
C3 = 220 uF 25 Vdc passo 2,5 mm
C4-C5 = 0,22 uF 400 Vdc passo 22 22mm
C6-C8 = 0,1 uF 400 Vdc passo 20 mm
C7-C9 = 10 uF 400 Vdc passo 5 mm
About power trafo
Prim. 220-230 volt
sec. 230 volt 600 mA ( if only one)
sec. 30 volt 50 mA for bias
sec. 3,15-0-3,15 volt 5 A
I check in my lab about pcb; maybe I have few ones
Ask for other info
Bye
Hi
the major selection is around EL84, not only for bias point.
In triode mode it is more easy to do
In my case I use a standard pair of 84.
But, if you want, you can try to trimm the anode or cathode resistors putting in parallel a different values
Walter
tubes4all,
I am very curious about your stereo system, as a whole.
What loudspeakers do you use for 15Hz music signals?
What is the longest dimension of your listening room?
Do you listen near-field?
What is your amplifier model, or is it custom?
Topology, and a few details, please.
Do you use a turntable and phono cartridge as one of your signal sources?
What is the low frequency resonance of your tonearm and cartridge (mass and compliance resonance)?
Do you have any warped LPs (~ 3Hz, typical)?
Thanks!
I am very curious about your stereo system, as a whole.
What loudspeakers do you use for 15Hz music signals?
What is the longest dimension of your listening room?
Do you listen near-field?
What is your amplifier model, or is it custom?
Topology, and a few details, please.
Do you use a turntable and phono cartridge as one of your signal sources?
What is the low frequency resonance of your tonearm and cartridge (mass and compliance resonance)?
Do you have any warped LPs (~ 3Hz, typical)?
Thanks!
Many people on this forum are knowledgeable enough to fill in the values themselves... You might notice Broskie posts many schematics with no values - he's showing the topology 🙂
15Hz -3db isn't exactly poor but I make my -3 point under 2Hz personally. Of course to do that, you need good transformers, and a good design otherwise it's easy to have breathing or motorboating or other LF instability.
I still regard "hi-fi" as 30Hz - 15kHz, too. My amps are measured flat within 1db from 6Hz to 50kHz (1W power) though.
I feel like you may not understand the cathodyne phase inverter theory enough, as you quoted my post yet made no direct response to what I was explaining regarding the signal take-off point..
I haven't the amp, is gone time ago by my friend.
But I try to find time to reproduce the input stage.
Walter
It’s simple it is a matter of distortion. Specially for PP. So the bandwidth of your speaker is not so important.
Your amplifier without the transformer is capable to do about 8Hz -3dB, so your transformer has limited induction.
Last edited: