Hi,
I'd be interested to see the results of a set of //ed 6C45s + a CCS/mu-follower.
The fact that paralleling them increases Cg-in actually helps reduce the 6C45s tendency to oscillate.
In practice it's not going to be easy since these are single triodes with a lot of pin connections to take care of.
Could it be that TINA assumed a lead acid battery?
Even if they turn out to be non-linear which is of course entirely possible, it does not even matter here since the discharge current is way too low to have any effect.
Ciao,
I'd be interested to see the results of a set of //ed 6C45s + a CCS/mu-follower.
The fact that paralleling them increases Cg-in actually helps reduce the 6C45s tendency to oscillate.
In practice it's not going to be easy since these are single triodes with a lot of pin connections to take care of.
Could it be that TINA assumed a lead acid battery?
Even if they turn out to be non-linear which is of course entirely possible, it does not even matter here since the discharge current is way too low to have any effect.
Ciao,
Could it be that TINA assumed a lead acid battery?
Even if they turn out to be non-linear which is of course entirely possible, it does not even matter here since the discharge current is way too low to have any effect.
Ciao,
NO. A simple search of the existing literature will show you conclusively that all battery chemistries have a non-linear impedance with frequency. Yes, it does matter because the AC ground for the transformer secondary will not be constant with frequency. This will cause distortion. I'm not sure why I bother answering these questions.
I agree the impedance vs frequency is chemistry dependent but most of the extracted models use only linear R's and C's hence no distortion per se. Nakamichi used this battery self bias scheme with great success, it's interesting to note it used a mercury battery and now folks have to hunt down a fairly obscure alkaline eqivalent. Never thought of trying to measure the distortion. In any case I would expect it to be a small fraction of the base ESR, 2.9 Ohms for a 9V alkaline at 1kHz.
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So, your logical attack on what I said is that if it's good enough for Nakamichi, it's good enough for us? Your "appeal to authority" argument is a well known fallacy.
I didn't say anything about measuring distortion of a battery. I said: the impedance of a battery is nonlinear with frequency. It is a well known phenomena in the Electrochemical Impedance Spectroscopy field.
I'm sorry, you seemed to be saying something that apparently wasn't there.
and you have all the solutions to all the problems and no improvements can ever be made, or what? Would you tell that to the OP then? "Your design is crap and don't bother designing a ribbon microphone preamp because it's already been done and nothing you can do will ever improve on them." That's basically what you appear to be saying. That doesn't sound very polite or even very helpful of you now does it?
It's all very well stating a fact, but it's of no use to anyone unless you make some attempt to quantify it. Heck, everything varies with frequency if you get down to small enough numbers. And if it's so 'well known', then it should be easy to put some numbers on it.
In this example, a PP3 varies its impedance by less than 30 ohms in the audio band. Other batteries even less. That's negligible compared with the total loading on the transformer.
http://www.omicron-lab.com/fileadmin/assets/application_notes/App_Note_Battery_Impedance_V1_0.pdf
Target is to build best possible tube preamp for a ribbon mic to use in (my home) studio. For this it requires to experiment with various preamp design topologies and various tubes.
Good question. Currently nothing. Otherwords it is benchmarked against itself . As soon as I reach top performance, I probably will compare it with others.
I would say currently target is flat frequency response in 20-20kHz -3dB at ends. Low THD, >0.1% or so, and low noise. Noise signal should be -115dB down to 200Hz, from 200Hz it may be < -100Db.
Yes I realize that contemporary SS are muuuuch better.
. As soon as I reach top performance, I probably will compare it with others. I would say currently target is flat frequency response in 20-20kHz -3dB at ends. Low THD, >0.1% or so, and low noise. Noise signal should be -115dB down to 200Hz, from 200Hz it may be < -100Db.
Yes I realize that contemporary SS are muuuuch better.
Hi,
Agreed.
One good place to start is to increase the efficiency of the mic itself by using thinner alu foil, a higher ratio SUT and ditto SUT at the input of the pre.
Once you have a signal level of say 0.5mV you can then optimize the circuit.
I realize I said this before but I really don't see any other way.
Ciao,
Agreed.
One good place to start is to increase the efficiency of the mic itself by using thinner alu foil, a higher ratio SUT and ditto SUT at the input of the pre.
Once you have a signal level of say 0.5mV you can then optimize the circuit.
I realize I said this before but I really don't see any other way.
Ciao,
It is not really SNR. It is what signal a preamp shows with 150R in input XLR.
Here is full pic http://www.diyaudio.com/forums/tubes-valves/234937-ribbon-microphone-preamp-60.html#post3882955
I am happy with it after 5K, and would like just to reduce flicker noise.
But I suspect 6S45P has increased flicker noise because was designed for RF not AF. Or it is I am unlucky to get these noisier ones. That is why I asked if EF86 (6J52P) is quiter.
Here is full pic http://www.diyaudio.com/forums/tubes-valves/234937-ribbon-microphone-preamp-60.html#post3882955
I am happy with it after 5K, and would like just to reduce flicker noise.
But I suspect 6S45P has increased flicker noise because was designed for RF not AF. Or it is I am unlucky to get these noisier ones. That is why I asked if EF86 (6J52P) is quiter.
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