As I told you in other thread you aren't able to discuss around the tubes and trafo.
The tube is E88C (single triode) not E88CC (double triode)
The gain og E88C is 64.
Also reading the pin you had to understand the difference.
But, please, stay here, probably you can learn a lot from other other members (not only me)
Ciao
The tube is E88C (single triode) not E88CC (double triode)
The gain og E88C is 64.
Also reading the pin you had to understand the difference.
But, please, stay here, probably you can learn a lot from other other members (not only me)
Ciao
Sorry Watly, indeed my mistake, an ec88 with a Mu of 65. In a srpp 32.5 max but still no 44.5 gain as in your measurements.
Or is the theory about srpp not correct? Please explain why your circuit is different from the theory.
Btw It helps if you upload schematics with better resolutions ....
Btw 2 the transformer still has many problems. Can you show 10kHz response of square waves? Not with the frequency limited AP system but with a system that can handle 1Mhz or even better 10MHz. I know we can't hear those frequencies but they help us make better designs and allow us to make better tradeoffs in our amplifier designs.
Please try to built it (input stage) then measure it then we can speak.
If you want I can send you for free two E88C Siemens gold pin. Fabolous ones.
The gain is around 2 dB more than the theory.
Ciao
A correction around gain; in the Srpp the bottom Rk is bypassed.
Following some formuals about gain of the E88C Srpp I got, in theory, around 50 with the bottom Rk bypassed and a load of 100kohm
So 42,5 in the real world is good ( I check on old paper of test)
Also the Zout is confirmed from the formulas, around 1,1kohm , with what I measured 1,2 kohm
Following some formuals about gain of the E88C Srpp I got, in theory, around 50 with the bottom Rk bypassed and a load of 100kohm
So 42,5 in the real world is good ( I check on old paper of test)
Also the Zout is confirmed from the formulas, around 1,1kohm , with what I measured 1,2 kohm
I used an online calculator :
http://mh-audio.nl/Calculators/SRPP.html
30x un bypassed, 34x bypassed. Very nice calculator.
http://mh-audio.nl/Calculators/SRPP.html
30x un bypassed, 34x bypassed. Very nice calculator.
In a quick search I could only find 1 e88c in my collection, but I know I have more, somewhere .... Doesn't matter, I used an ec8010 instead and it came very close to the theoretical gain. I still think there is something wrong with your measurements, 42.5x is way off the limit. Have you tested the tube curves?
This is the screenshot of the link you used.
As you see the gain value is 50,75 times = 34,11 dB (max)
You have confused the number of times with db!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
And the check is that you have write 30x and 34x.
This is another error from you!!!
Also the Zout is close at what I have calculated and verified on desk.
One note: you haven't seen the error on schematic.
I have the curves of E88C traced wtih my Sofia but I have to translate in jpg through the win98 pc dedicate to it.
Unfortunatley Sofia is in pension because it is no longer mantained by Audiomatica even I ma pushing to have a total revision.
I am planning to get the ROE tube tester.
The values from data sheet are close from Sofia; the gain varies from 64 to 67.
As you see the gain value is 50,75 times = 34,11 dB (max)
You have confused the number of times with db!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
And the check is that you have write 30x and 34x.
This is another error from you!!!
Also the Zout is close at what I have calculated and verified on desk.
One note: you haven't seen the error on schematic.
I have the curves of E88C traced wtih my Sofia but I have to translate in jpg through the win98 pc dedicate to it.
Unfortunatley Sofia is in pension because it is no longer mantained by Audiomatica even I ma pushing to have a total revision.
I am planning to get the ROE tube tester.
The values from data sheet are close from Sofia; the gain varies from 64 to 67.
I don’t think it’s a mistake i made but a mistake in the app.
Look at the differance of what the app dos on my ipad. And still not 42,5x
btw, i do not like electrolytics in the signal path.
Look at the differance of what the app dos on my ipad. And still not 42,5x
btw, i do not like electrolytics in the signal path.
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It’s not the app that is the problem .. you clearly misread dB for voltage gain at post #525, and the reason your results are slightly different from Walt in your recent post is that you have entered mu as 64, and not 65 as he has it.
Anyway, I think everyone can see that voltage gain of 42 is credible, and saying that you don’t like Ck is irrelevant.
What I said that you confused the times of gain with dB!!!!!!!!!!!!!!!
Have you understood or not!!
Then the 42,5 times agains 49 can be reasonable in the real world due the tube differences and it is not a problem for me.
A Zout I measured is 1,2 kohms, little bit higher but is comaparable with calculator.
Maybe If I change the working point with more Ia I can reach those values
Then this calculator is a little bit limited due the fact that the Rload is not considered; It must be considered so a window with a value maybe will help to have the real values.
Have you understood or not!!
Then the 42,5 times agains 49 can be reasonable in the real world due the tube differences and it is not a problem for me.
A Zout I measured is 1,2 kohms, little bit higher but is comaparable with calculator.
Maybe If I change the working point with more Ia I can reach those values
Then this calculator is a little bit limited due the fact that the Rload is not considered; It must be considered so a window with a value maybe will help to have the real values.
The lasts post are OT so I can stop here around the discussion on gain.
What I said about input stage with E88C I think is enough to understand if it will be interesting for the purpose
Walter
What I said about input stage with E88C I think is enough to understand if it will be interesting for the purpose
Walter
Why do people here use a transformer with about 2500 Ohms?
Most of these transformers have a lack of inductance and because of that the tube runs out of current (clipping)
Oh, Walty, don't response to this, You don't understand transformers at all so don't bother us with you "knowledge"
Most of these transformers have a lack of inductance and because of that the tube runs out of current (clipping)
Oh, Walty, don't response to this, You don't understand transformers at all so don't bother us with you "knowledge"
Then you are a smart man. Lots of credits to you. At 5K Ohm your transformer needs about 40H ( for 20Hz) But even at 32H there are no big problems. Most 2k5 Ohm have low frequency problems from the start because of the to low inductance of the transformer.
And for many other reasons a higher Ra is a good choice
they did sound great, anyway the inspiration came from Sephie and her Skunkie 300b design.... https://www.diyaudio.com/community/threads/skunkie-designs-300b.380215/