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Old 7th March 2011, 05:20 PM   #81
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Hi Ale;

I did not calculate equivalent L, it does not matter: what matters, is corner frequency. But if you want to, you can build an equivalent schematic, write an equation from it, then solve. It is simple: take an amp with finite amplification factor, take reactive capacitance and resistors, and solve for input impedance.

Anatoliy
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Old 7th March 2011, 07:31 PM   #82
hihopes is offline hihopes  South Africa
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Hi Anatoliy, any news on pse 4p1l yet?
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Old 7th March 2011, 07:54 PM   #83
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Quote:
Originally Posted by hihopes View Post
Hi Anatoliy, any news on pse 4p1l yet?
Yes!

I had 7 tubes, bought from 2 different e-pay sellers from Ukraine. Measured all of them on -17V on first grid, 220V on anode. Idle currents are:


1. Feb 1966 50 mA
2. March 1976 42 mA
3. Feb 1966 45 mA
4. Feb 1966 44 mA
5. Feb 1966 41 mA
6. Feb 1966 43 mA
7. March 1976 50 mA

That means, differences in idle current on the same voltages is less than 10 percent.

I did not measure yet how well it performs, but Diana Krall sings very well, very real soundstage, I hear clear details. Obviously, output power is 5W per channel now, because when I connect the same 8 Ohm speakers to 16 Ohm taps, I see the same level on indicators.
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Old 7th March 2011, 08:07 PM   #84
hihopes is offline hihopes  South Africa
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Just as clear as single tubes? The reason I ask is I am thinking of using 3 per channel, aiming for about 6.5w with low distortion and good damping factor

Last edited by hihopes; 7th March 2011 at 08:12 PM. Reason: add details
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Old 7th March 2011, 08:11 PM   #85
mogliaa is online now mogliaa  United Kingdom
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Quote:
Originally Posted by Wavebourn View Post
Hi Ale;

I did not calculate equivalent L, it does not matter: what matters, is corner frequency. But if you want to, you can build an equivalent schematic, write an equation from it, then solve. It is simple: take an amp with finite amplification factor, take reactive capacitance and resistors, and solve for input impedance.

Anatoliy
Hi Anatoliy,
You lost me there. I thought it was the L what it matters. Why is the corner frequency what you need and how do you calculate it?
i may need to find a text covering this, as I haven't done any proper circuit analysis for more than 15 years, so will struggle with this :-(
cheers,
Ale
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Old 7th March 2011, 08:36 PM   #86
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Quote:
Originally Posted by hihopes View Post
Just as clear as single tubes? The reason I ask is I am thinking of using 3 per channel, aiming for about 6.5w with low distortion and good damping factor
I am listening now to 2 per channel. Subjectively like more of highs, most probably because with the same transformers internal resistance of tubes in sum is twice lower, and twice lower is load resistance.

I am going to measure it later.
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Old 7th March 2011, 08:39 PM   #87
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Quote:
Originally Posted by mogliaa View Post
Hi Anatoliy,
You lost me there. I thought it was the L what it matters. Why is the corner frequency what you need and how do you calculate it?
i may need to find a text covering this, as I haven't done any proper circuit analysis for more than 15 years, so will struggle with this :-(
cheers,
Ale
Ale, R and C is enough to calculate dependence of output resistance on frequency; phase does not matter so no need to recalculate to an equivalent L.

You may assume an integrator around an amp with finite amplification factor, and current mode output. It is enough to select R and C values in ballpack with desired frequency response. I am not writing an article about science of gyrator; I am describing how I am toying with a small output amp with no negative feedback around it.
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Last edited by Wavebourn; 7th March 2011 at 08:42 PM.
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Old 7th March 2011, 10:36 PM   #88
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Also, subjectively less boomy lows, looks like damping factor plays it's role. And 5W per channel from SE amp is quite enough to listen to classical music and jazz, with Magnavox boombox as a stereo speaker.
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Old 7th March 2011, 11:23 PM   #89
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I can't stop listening, to measure... Just listening, and listening, and listening...

Click the image to open in full size.
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Old 8th March 2011, 03:38 AM   #90
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Now I need a very clean 6.3V source, to power 6S17K-V tubes in MC phono corrector...
I will have both MC and MM correctors inside, with L-R correction.
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