Maybe this is very location dependent... I want to find a driver tube being easily accessible here (Germany). 6U8 is too exotic.
Some basic knowledge would not hurt.....2.22Vpk-pk is 0.78VRMS (divide pk-pk value by 2.83 to get RMS value).
A little less arrogance would also not hurt, @daanve . Simple factor 2 error. 1.57V RMS was correct.
Sorry no.
I don't mean to be arrogant, but until now you made some clumsy mistakes, agree?
To get RMS value of pk-pk voltage divide by 2.83. To get RMS value of pk voltage divide by 1.41. This is basic stuff.
You divide pk-pk voltage by 1.41 to get RMS voltage....wrong!
Also, in your first E88CC sim, the anode-cathode voltage is ~ 200V, and anode current ~ 10mA.
That is 2 watt dissipation....your tube will not last long.
So you really have to learn and appreciate people to "teach and correct" you instead of calling them arrogant (einverstanden?)
I don't mean to be arrogant, but until now you made some clumsy mistakes, agree?
To get RMS value of pk-pk voltage divide by 2.83. To get RMS value of pk voltage divide by 1.41. This is basic stuff.
You divide pk-pk voltage by 1.41 to get RMS voltage....wrong!
Also, in your first E88CC sim, the anode-cathode voltage is ~ 200V, and anode current ~ 10mA.
That is 2 watt dissipation....your tube will not last long.
So you really have to learn and appreciate people to "teach and correct" you instead of calling them arrogant (einverstanden?)
@daanve , I know the RMS voltage is Vpp/2/1.41. It was a mistake I made when annotating the schematic. The important part for my "endeavour" is the RMS voltage, which was more or less in line with what I am looking for.
And sure, when I used the E88CC model instead of EC88C because I did not look closely enough, that was also a mistake. The E88CC being pretty common and the E88C not so (at least for me) might explain it (for you likely not).
The info that the E88CC has a much lower max. anode voltage and max. dissipation than e.g. the 6DJ8, although when searching for supplies, shops / sites they are interchangeable, is of course appreciated. And I said a couple times already above that I am less knowledgable than most of you more experienced. I really appreciate when people explain and correct. But the way you do is very arrogant.
And sure, when I used the E88CC model instead of EC88C because I did not look closely enough, that was also a mistake. The E88CC being pretty common and the E88C not so (at least for me) might explain it (for you likely not).
The info that the E88CC has a much lower max. anode voltage and max. dissipation than e.g. the 6DJ8, although when searching for supplies, shops / sites they are interchangeable, is of course appreciated. And I said a couple times already above that I am less knowledgable than most of you more experienced. I really appreciate when people explain and correct. But the way you do is very arrogant.
Sorry for my "arrogance" but you sounded somewhat stubborn, that's why.
I guess that the inductance values of the output transformer in your sim (23H primary L; 0.056 secondary L) are randomly chosen?
Because that is an impedance ratio of ~ 1600 ohm primary with a 4 ohm secondary load.
1600 ohm is way too low load for 300B when driving loudspeakers with curved impedance.
I guess that the inductance values of the output transformer in your sim (23H primary L; 0.056 secondary L) are randomly chosen?
Because that is an impedance ratio of ~ 1600 ohm primary with a 4 ohm secondary load.
1600 ohm is way too low load for 300B when driving loudspeakers with curved impedance.
Not really randomly. They were from Hammond data I found in a thread (for 8 Ohms, secondary divided by 2 for 4 Ohms). Seems the values were off.
I had not validated the primary results in 3k-3k5. I think 23H:31mH for 4 Ohms is more reasonable? That also results in higher Pmax, which makes sense.
Thanks for the correction.
EDIT: I read that up to 5k primary is even better. Will check that too.
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Yes, impedance ratio equals inductance ratio here. 23H:31mH is 3k:4R.
The secondary feedback tap in your other sim is actually a "16" ohm tap.
In inductance (to sim), with 23H primary L, secondary inductances will be 31, 62 and 124 mH for 4, 8 and 16 ohm load impedance respectively
for a 3k primary impedance output transformer.
The secondary feedback tap in your other sim is actually a "16" ohm tap.
In inductance (to sim), with 23H primary L, secondary inductances will be 31, 62 and 124 mH for 4, 8 and 16 ohm load impedance respectively
for a 3k primary impedance output transformer.
As daanve says 6922 is the equivalent of E88CC not E88C. They are certainly not unobtainium. Also Russian 6N23P is another equivalent, and generally less expensive
Just a general comment, because I've seen similar threads before, but what is the obsession about making a particular value of sensitivity for full output exactly equal to some (digital) source's output at clipping? Does the system have no volume control and is intended to run all-out, full blast all the time?
Because if it has a volume control, some gain margin would be expected in any reasonable design. Maybe 6dB, or with a variety of analog sources, maybe 12 or even 20dB. That's what volume controls are for.
All good fortune,
Chris
Because if it has a volume control, some gain margin would be expected in any reasonable design. Maybe 6dB, or with a variety of analog sources, maybe 12 or even 20dB. That's what volume controls are for.
All good fortune,
Chris
Looking back to the beginning of the thread I see that several wiser heads asked the same question within the first 6 posts, but no answer.
All good fortune,
Chris
All good fortune,
Chris
For LTSpice users:
As I wrote earlier: the LTSpice voltage source voltage value is peek, so setting it 2.22V means 2.22V peek, not peek_to_peek, so it's 1.57V RMS.
As I wrote earlier: the LTSpice voltage source voltage value is peek, so setting it 2.22V means 2.22V peek, not peek_to_peek, so it's 1.57V RMS.
TO states to have a preamp with "max 2VRMS output" and wants a power amp with 2VRMS input sensitivity for full output.
That makes sense, though, when the numbers are correct (....), in this case I'd design the power amp to have 1VRMS input sensitivity for headroom and knowing there is a volume control in front.
The SRPP Waltube posted uses E88C. As I said above, I found one source for that now.
6922 and E88CC would be easy to get here, I did not mean them with "unobtanium".
6n23p I could only get from Ukraine via Ebay (and rather expensive).
For the single-stage triode driver I posted above, only 6DJ8 / ECC88 have high enough max. anode voltage and power dissipation, if I am not mistaken. I can buy them here, but there are not many offers.
Yes, I should not have mixed Vpp (I had meant Vp anyway) and Vrms in the schematic.
Thanks @daanve . I will recalc the current options with the corrected OT impedance and see where that gets me.
Bias voltage 5.1 V and bias resistor of 500 Ohm means you're biasing the ECC88 at about 10 mA (okay). Anode-cathode voltage is about 210 V (exceeds the datasheet limit of 130 V). Dissipation is 10 mA x 210 V = 2.1 W (exceeds the datasheet limit of 1.8 W). The tube is running too hot.
I currently do not expect to use analog sources. But your advice are right to plan for headroom is good and correct (and was given before in this thread).
Thanks. Looks like the the 6DJ8 is the only of these which would be within specs.