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    the safety precautions around high voltages.

Chinese Single Ended 12AX7+EL34: improvements?

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The way to have a poor tube amp, in my opinion.
No test lab that can ceritfy the performances! This is the major problem of this tye of kit ( and in general)
Jut to be clear, in attach a circuit, simply and certified.
With freq. answer and thd vs frequency with two different I bias.
The trafo are custom but also with Hammond is possible to get a good results

Walter
 

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6N1P spice model

* Generic triode model: 6N1P_AN
* Copyright 2003--2008 by Ayumi Nakabayashi, All rights reserved.
* Version 3.10, Generated on Sun Jan 12 18:59:00 2014
* Plate
* | Grid
* | | Cathode
* | | |
.SUBCKT 6N1P_AN A G K
BGG GG 0 V=V(G,K)+-0.42063507
BM1 M1 0 V=(0.007566675*(URAMP(V(A,K))+1e-10))**-0.43818786
BM2 M2 0 V=(0.77391879*(URAMP(V(GG)+URAMP(V(A,K))/29.878541)+1e-10))**1.9381879
BP P 0 V=0.0022884667*(URAMP(V(GG)+URAMP(V(A,K))/38.606817)+1e-10)**1.5
BIK IK 0 V=U(V(GG))*V(P)+(1-U(V(GG)))*0.0013346379*V(M1)*V(M2)
BIG IG 0 V=0.0011442333*URAMP(V(G,K))**1.5*(URAMP(V(G,K))/(URAMP(V(A,K))+URAMP(V(G,K)))*1.2+0.4)
BIAK A K I=URAMP(V(IK,IG)-URAMP(V(IK,IG)-(0.001233721*URAMP(V(A,K))**1.5)))+1e-10*V(A,K)
BIGK G K I=V(IG)
* CAPS
CGA G A 1.6p
CGK G K 3.2p
CAK A K 1.5p
.ENDS
 
The 6N1P is not a proper tube to do that job.
The gain is similar to 6922/6H23 but the Rp in greater and Gm is lower,
Much better the 6922 in Srpp so it can swing a good voltage with low Zout and reasonable low distortion.
Another good solution is 5965 always in Srpp.


And leave the simulation, the real world is different from virtual.
Try to use the solder and stuff.

Walter
 
Ciao Walter,

thanks to suggest the 6922, I've found the models here and will simulate it as well: Vacuum Tube SPICE Models

I'm not interested in the SRPP because it hasn't enough swing for the specific purpose.
Do not assume by preconcept that people do not experiment with the solder just because they are into simulations. I support the solder with simulations, as I've found it to be a faster way to get results I like. YMMV.

I will report how the 6922 will work with this specific circuit.
 
Are you sure about swing with 6922?
I think you haven't test it in a right way.
In attach the real test on Srpp of the circuit sent post ago
With 450 mV in you got 20 Vout rms with a BW of around 200 kHz and distortion less than 1%; in this way the grid of EL34 or KT88 will be driven good
This is E88C, single triode

In addition a freq. response of a Srpp withh 6922, 1 Vin, 23 Vout,

I have a lot of preconcept about simulation until the real circuit is done with real test.
And the comparison is verified.
When there are involved the trafos and inductors this is not possible

Walter
 

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Thanks for your comment Walter,

if you look at the circuit I've posted, I have a cathode driven output tube à la Tubelab with local feedback anode-to-grid. That causes to add the swing of the grid (that is a percentage of the anode swing) to the driver's swing. That's why I went to Rod Colemans' shunt driver, that working on a vertical load line is able to swing 100 Vrms with a THD lower than 1 and mainly 2nd harmonic (due to the knee at the bottom of the curves).
 
Why you are looking for a complicate life?
30-35 wrms? with 4,3% of THD, It is a joke?
How much is the thd at low freq. and high freq? 30%?
In which way you can simulate the trafo if you aren't able to get the real parameters of it?
At mid frequency is possible to assume that the trafo is quite ideal but at the ends is another story,
In attach three different s.e, trafo under test.
The test is done with a particular sw by Fabrizio Montanucci in Audioreview magazine in Italy where I write .
It is possible to measure the inductors and caps.
You can see the differences on each one.
The shape of Z in function of frequencies.
As you see the resonance varies between 2 kHz and 3 kHz with different Q.
After the resonance the phase switch from +90 to -90° this because the trafo is acting, less or more, as capacitor (due the parasitic)
In which way you can simulate this?

These are the real problems in tube amps.
Not the swing at 100 Vrms that is not necessary in your case
And the use of sand while you can reach a very good results in other simply way also to spent money for OT


Walter
 

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Walter, I appreciate your warnings but please go off the pulpit, thanks.
That behaviour is ruining the thread.

If you are not interested in implementing SS in tube amps (and this is clear), this doesn't mean all others don't have to.
If you are not interested in simulate tube amps (and this is clear too), this doesn't mean all others don't have to, as a starting point.

Please, be kind. Your point is clear.
Let us kids play with sand.
 
I have read your first post.
This is why I have wrote some consideration.
And there isn't pulpit; there are technical aspect that must be take in consideration that you can't resolve with simulation.

You can use all the sand you want and all simulation, of course.
Let me to criticize in the proper way.

Bye

Walter
 
The way to have a poor tube amp, in my opinion.
No test lab that can ceritfy the performances! This is the major problem of this tye of kit ( and in general)
Jut to be clear, in attach a circuit, simply and certified.
With freq. answer and thd vs frequency with two different I bias.
The trafo are custom but also with Hammond is possible to get a good results

Walter


Looks like a simple elegant circuit. What do you think about substituting 2X 6L6 tubes instead of the KT150?
 

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  • Fig.14-SE KT150.jpg
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Instead of doing the coffee break I switched the input tube to a ECC88 with good results, but I still have a predominant 2nd harmonic even at low power.

I only simulated the version with one output tube, because that's the version I have on the laptop I'm using now. This evening I will simulate the PSE.

attachment.php


These the results at 15 Wrms:
Code:
Harmonic	Frequency	 Fourier 	Normalized	 Phase  	Normalized
 Number 	  [Hz]   	Component	 Component	[degree]	Phase [deg]
    1   	1.000e+03	1.535e+01	1.000e+00	   -0.87°	    0.00°
    2   	2.000e+03	3.526e-01	2.297e-02	  -95.93°	  -95.07°
    3   	3.000e+03	1.923e-01	1.253e-02	    1.45°	    2.32°
    4   	4.000e+03	3.760e-02	2.449e-03	  -73.00°	  -72.13°
    5   	5.000e+03	6.268e-02	4.083e-03	 -177.46°	 -176.60°
    6   	6.000e+03	2.505e-02	1.632e-03	   98.60°	   99.47°
    7   	7.000e+03	2.381e-02	1.551e-03	    2.95°	    3.82°
    8   	8.000e+03	9.736e-03	6.343e-04	  -78.84°	  -77.98°
    9   	9.000e+03	7.239e-03	4.716e-04	 -174.04°	 -173.17°
Total Harmonic Distortion: 2.669876%(2.669969%)
 

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I have one question about SE amps: it is preferrable to hit Vg1=Vk before Ik=0, or the opposite?

I would say the former, because you still have control on the speaker due to the high current flowing through the tube, otherwise with no current on the tube the speaker is no more controlled, but that's just my guess and I could be wrong.

Thanks
Roberto
 
Looks like a simple elegant circuit. What do you think about substituting 2X 6L6 tubes instead of the KT150?

Hu

I use it with EL34, Kt88, also 300B, never for parallel but the Zout and swing of srpp with E88c is fine for that use.
It is incredible as this triode is very good; and the price is not so high for a nos/nib
On the circuit the Fb is only 6dB


Walter
 
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I'm looking at the datasheet of the FQPF9P25 ( https://www.mouser.it/datasheet/2/308/FQPF9P25-D-1809691.pdf ) and here I have a limit on the Vds that could make me move towards the FQPF9N50 ( https://www.mouser.it/datasheet/2/308/FQPF9N50CF-D-1810101.pdf ) or reduce the local feedback on the EL34s.

By the way, this is the circuit with two EL34s in parallel.

attachment.php


and these the results at 30Wrms:
Code:
Harmonic	Frequency	 Fourier 	Normalized	 Phase  	Normalized
 Number 	  [Hz]   	Component	 Component	[degree]	Phase [deg]
    1   	1.000e+03	2.165e+01	1.000e+00	   -1.66°	    0.00°
    2   	2.000e+03	4.459e-01	2.059e-02	 -100.93°	  -99.27°
    3   	3.000e+03	2.672e-01	1.234e-02	    4.76°	    6.43°
    4   	4.000e+03	8.060e-02	3.722e-03	  -72.40°	  -70.74°
    5   	5.000e+03	9.459e-02	4.368e-03	 -174.10°	 -172.44°
    6   	6.000e+03	4.972e-02	2.296e-03	   97.96°	   99.62°
    7   	7.000e+03	3.956e-02	1.827e-03	    3.07°	    4.73°
    8   	8.000e+03	2.149e-02	9.923e-04	  -87.12°	  -85.46°
    9   	9.000e+03	1.436e-02	6.630e-04	  177.01°	  178.67°
Total Harmonic Distortion: 2.488472%(2.488905%)
 

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  • ECC88&EL34_PSE.jpg
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