Plate voltage - answer to post # 28
Hi Richy,
Plate voltage 470, plate current 165mA, screen current approx 100mA.
Looking at the specs my plate voltage may be a little to high.
The front end is a copy of Morgan Jones Crystal Palace amplifier (added LL1676 phase splitter) directly coupled to 6h30P driver using Gary Pimms CCS driven into LL1660S (IT).
regards
Frank
Hi Richy,
Plate voltage 470, plate current 165mA, screen current approx 100mA.
Looking at the specs my plate voltage may be a little to high.
The front end is a copy of Morgan Jones Crystal Palace amplifier (added LL1676 phase splitter) directly coupled to 6h30P driver using Gary Pimms CCS driven into LL1660S (IT).
regards
Frank
This is the link of Audiomatica where is possible to dowload the manual of Sofia:
http://www.audiomatica.com/download/sofman.pdf
On page 7-1 there is a menu about output file
Ciao
Walter
http://www.audiomatica.com/download/sofman.pdf
On page 7-1 there is a menu about output file
Ciao
Walter
Dear Waltube: I apologise, I stand corrected. I have the manual also; I bought mine in '95 I believe. I don't think a bit map will help with the question re plotting on an Excel file tho. What I believe would be needed are the raw ADC values that the unit outputs to the computer.
I would be a bit nervous re downloading new SW for the unit; we Americans have a saying regarding fornicating with functional units!!!
I would be a bit nervous re downloading new SW for the unit; we Americans have a saying regarding fornicating with functional units!!!
I don't have enough familiarity to know what interface is used with the Sophia, but I'm assuming it is a parallel or serial port given its vintage. You could just install the newer version of the software on another machine to evaluate its performance. Were I so lucky to own one of these I would definitely give that a shot - of course I live on planet linux so frequent changes and experimenting are a way of life for me..
Presumably you have a back up copy of the original software for the day when that laptop grenades itself?
If you plot the KT120 (by SOFIA) with 21 curves then you print the bmp file I suppose that is possible to study different points where you can play with this tube.
In next future I will build a mono with four KT120, triode connection in push-pull.
Now it is running (with the same chassis) a prototype with four 300B in p-p.
This is the photo:
http://www.multitask.it/300b/fabfour.jpg
I am very interested on this tube.
Ciao
Walter
In next future I will build a mono with four KT120, triode connection in push-pull.
Now it is running (with the same chassis) a prototype with four 300B in p-p.
This is the photo:
http://www.multitask.it/300b/fabfour.jpg
I am very interested on this tube.
Ciao
Walter
Amps look nice - power output level of around 50 - 60W?
I like the JJ 300B a lot and have used them in both PP amps (The 300B PP in VTV issue #12 was my design Issue 12 Cover) and in a number of SE amps including the one I currently use.
The monos are double p-p of 300B.
The rms power is 45 w rms but, due to particular values of impedance on opt, I got 70 watt on 4 ohms.
There is a single secondary. Each tube run at 50 mA
The capacitance is 2.500 uF at 450 Vdc ( 8 x 330 uF, on last version); The Vdc for 300B is 410 V.
They have a feedback on 6 dB and 10 dB or nothing ( there is a switch).
The open loop BW is 80 KHz; with 10 dB I got more than 110 KHz.
The JJ seem to be a good 300B.
I made also a similar amp with 2A3-40, that is better for hum (I will use only ac filaments); it is a 300B with 2,5 v filaments. The electrical spec are similar to a 300B.
Now I am testing the 300BC with graphite anode by Shuguang.
Ciao
Walter
The rms power is 45 w rms but, due to particular values of impedance on opt, I got 70 watt on 4 ohms.
There is a single secondary. Each tube run at 50 mA
The capacitance is 2.500 uF at 450 Vdc ( 8 x 330 uF, on last version); The Vdc for 300B is 410 V.
They have a feedback on 6 dB and 10 dB or nothing ( there is a switch).
The open loop BW is 80 KHz; with 10 dB I got more than 110 KHz.
The JJ seem to be a good 300B.
I made also a similar amp with 2A3-40, that is better for hum (I will use only ac filaments); it is a 300B with 2,5 v filaments. The electrical spec are similar to a 300B.
Now I am testing the 300BC with graphite anode by Shuguang.
Ciao
Walter
So what is that I_max? idle current? peak AC current?
For the KT120 I think a 400V/120 mA idle point would be acceptable. So for two, idle at 240 mA, and be able to swing +/-350V. Which would be done with a load of ~1k5. Now if you wanted PP, the H-K Citation II output would be ideal... for four that is.
cheers,
Douglas
For the KT120 I think a 400V/120 mA idle point would be acceptable. So for two, idle at 240 mA, and be able to swing +/-350V. Which would be done with a load of ~1k5. Now if you wanted PP, the H-K Citation II output would be ideal...
for four that is.cheers,
Douglas
Bass guitar amp
got this crazy thought to try a PSE with 2x KT120
trafos are available
and even UL tapped
looking for a cheap IT
maybe frequency limiting could even be of advantage
I figure pushpull would probably be a better choice in this application? A cheap and cheerful 80W ought to be possible with these tubes and the right OPT.. Bass generally requires more power than is practical with PSE, and I am not sure what sort of tone you would get with a PSE either.. Could be an adventure I suppose..
yes, my thought too
but more 'power' consuming
its for domestic use
for stage use I wouldnt
I'm happy with 30watt, or so
and like you said, 'the adventure', and learning
I figured that a bass amp will demand less, in terms of sound quality
hell, I could choose a high power classD or mosfet
but I dont need no freaking 500watt
well, and I have this strange urge to learn a bit more about tube building
I'm now building a rather big midbass horn with 15" woofer
and expect that will give me a natural BIG, clean and powerful sound
you see, to me personally the sense in this is the sum of it all
and much less about what's better or worse
but ofcourse you are absolutely right
nice figures, thanks Douglas
thinking about using a 6C19n for driver, through IT 1:2
just thoughts
maybe ecc99 would make more sense
for Bas:
The output trafo are made from Trau (Venice) under my spec.
Regarding the KT120, now I have completed a simply project for a p-p of EL34 in triode and pentode mode, class AB1. This project will be presented ona magazine for DIY in Italy; the other tubes are 69922 in input and ECC99 in output.
The power is 24 w in triode; 45 w in pentode
Is it running also with KT120; the resuslts are very interesting mainly for the possibility to set the bias current (with 440 Vdc) at 100 mA; in this situation the the powe is similar to EL34, in both configuration, but I can stay in class A for more than 50% of the power.
I have also Sofia and I can confirm about the good results of the test.
Ciao
Walter
The output trafo are made from Trau (Venice) under my spec.
Regarding the KT120, now I have completed a simply project for a p-p of EL34 in triode and pentode mode, class AB1. This project will be presented ona magazine for DIY in Italy; the other tubes are 69922 in input and ECC99 in output.
The power is 24 w in triode; 45 w in pentode
Is it running also with KT120; the resuslts are very interesting mainly for the possibility to set the bias current (with 440 Vdc) at 100 mA; in this situation the the powe is similar to EL34, in both configuration, but I can stay in class A for more than 50% of the power.
I have also Sofia and I can confirm about the good results of the test.
Ciao
Walter
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