mhardy6647
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Yes, military tubes were often considerably ruggedized compared to their consumer counterparts. Compare a Bendix 5992 to a consumer grade 6V6GT, for example.G shock resistance, too, in some cases.
Nah, the Apollos were all resistor-transistor logic in SSI ICs. Radios might have been tube based, I dunno.We went to the moon on tubes.
Yes, military tubes were often considerably ruggedized compared to their consumer counterparts. Compare a Bendix 5992 to a consumer grade 6V6GT, for example.
Nah, the Apollos were all resistor-transistor logic in SSI ICs. Radios might have been tube based, I dunno.
Ima a nooB with tube/valve gear. Is it actually a transconductance curve with all that transformer action, is it linear? The plate reactance that issue is Miller capacitance?transconductance, cathode current, inter-electrode capacitances
Ima a nooB with tube/valve gear. Is it actually a transconductance curve with all that transformer action, is it linear? The plate reactance that issue is Miller capacitance?
Transformer coupled stages are a different story. Capacitor coupled stages (like inside an amplifier before the power tubes) will track the plate curves pretty closely.Ima a nooB with tube/valve gear. Is it actually a transconductance curve with all that transformer action, is it linear? The plate reactance that issue is Miller capacitance?
Thanks. Those are transconductance curves. Not exactly sure yet how the graph works yet because I'm not accustomed to thinking in valves and high voltage stuff like these devices. The amplification factor is the range where amplification occurs on the transconductance curve and it's shown in what would be analogous to hFe with a transistor? A gain number?Here is a 5670 data sheet take a look at page 3 for the transconductance curve.
Thanks DT
Yeah, mu is essentially equivalent to hFe.Thanks. Those are transconductance curves. Not exactly sure yet how the graph works yet because I'm not accustomed to thinking in valves and high voltage stuff like these devices. The amplification factor is the range where amplification occurs on the transconductance curve and it's shown in what would be analogous to hFe with a transistor? A gain number?
Ogidoki... so the lesser the grid voltage the more linear the transconductance mu curve for this specific valve/tube? But the shorter the range of useful linearity whilst being the straighter of the lines of mu? How does this fit into the grand scheme of valve/tube stuff?Yeah, mu is essentially equivalent to hFe.
A triode is more or less equivalent to how an n-channel JFET works. Plate = Drain, Grid = Gate, Cathode = Source. The curves are a little different - triodes are actually way more linear sans feedback - but the basic mechanics are largely the same.
Even when I record my own bass, using my own mics, in my own living room, and play it back in the same room, and do my best to make it sound as close as I can to what I hear in person....
It's never very close to live.
2 channel stereo, itself, is not realistic.
Okay so some translation is necessary - mu is a product of multiplying the internal resistance (usually termed plate resistance or Rk-a) by the transconductance.Ogidoki... so the lesser the grid voltage the more linear the transconductance mu curve for this specific valve/tube? But the shorter the range of useful linearity whilst being the straighter of the lines of mu? How does this fit into the grand scheme of valve/tube stuff?
See what you seem to be missing people is that all tubes even of the same type are substantially different in construction. And they were not designed to sound the same.
You should understand that tubes were not made to the same specification, even the same tube types.
And there was no STANDARD for frequency response (not to mention many tubes used in audio amplifiers were not designed for audio) back in the post WW II period that I am aware of. Are you? I've not seen references to 20 hz - 20 khz until like the 1970s.
SO:
would it not be stranger for the tubes to sound alike than it would be for them to sound different?
When you swapped the KT 120's for the 6550's - did you readjust the bias? So, whether you optimized the bias or not - you heard a difference. To verify we could measure a couple of things. First, you could test for output impedance changes - affects damping factor. Being a tube amp we need to be careful - no open circuit voltage measurements! I would try a 100 ohm load and consider that "open circuit" to get the reference voltage at a given driven frequency. Being a tube amp we can short circuit the output with no fear as we lower the load until the output voltage is half the reference voltage. That load resistance is the output impedance at the driving frequency. Best to do sweeps with fancy test gear to plot this by frequency. Another way is to sweep your system with a measurement microphone and plot spl versus frequency. Compare the plots for between output tube plots for measured differences.Though I wasn't expecting any particular sonic difference, which likely means it wasn't an expectation bias in particular, that's not the only form of sighted bias. I still could have been imagining the differences.
Also, I'm pretty sure from what I've since that, taken together, tubes and the full amp circuit, I'm likely not getting any more power out of the KT120s vs the 6550s. (I think the amp puts a limit on that, and that the amp would have had to be designed to specifically take advantage of a higher power tube. At least that's what I think I've gleaned from conversations about those tubes).
It will be used to replace microphone parts, is there a vacuum tube with good specifications for low distortion? The existing vacuum tube is 6AU6.This DIY tube pre amp seems to have been decent with low distortion, or? Tube pre amp with tube ECC88
I'm not the one saying that tubes all sound the same. That is what I am responding to.Only a few tubes were designed for the analog amplification part. Most tubes are purpose designed. For rolling tubes they need to be within certain parameters to begin with otherwise they won't bias properly.
And yes they are different in construction and for different reasons but work on the same principle.
Audio tubes were all designed to 'sound' the same. Tubes from a similar family, when used correctly' all have very similar frequency response.
It usually is the components around the tube (and the circuit) which determines the 'sound' the device as a whole has.
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I am aware of that.. are you aware of the reasons for that ? Are you aware what determined the frequency response ? Do you reckon it was the tubes or the transformers and circuits ?
Would it not depend more on the circuit like topology, feedback and components around it for them to sound different.
You do realize all transistors also measure differently and all other active components also measure differently and maybe purpose designed where the purpose is not audio yet used that way ?
Tubes are clearly different sounding. I can tell they are because I can hear it with some of them.