really great tube for audio
surprising!
surprising!
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signal source
dac pcm63p NOS
round wire potentiometer 25 ohm.for i / v converter and volume control
PC900 triode with plate choke
AZ1 power supply channels individualized rl
dac pcm63p NOS
round wire potentiometer 25 ohm.for i / v converter and volume control
PC900 triode with plate choke
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
AZ1 power supply channels individualized rl
An externally hosted image should be here but it was not working when we last tested it.
Last edited:
with the help of a carpenter friend
to assemble and glue the pieces
to cut the pieces was used
a machine assisted with AutoCAD
I show my support design
iron built
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I am a bit glad speakers came up, for as much info on SET amps there is very little info on this site for modest high efficiency speakers, what are people without cad assisted machines doing for speakers. Are something like econo waveguides a good route to take for and amp this small powered. I have a pair of BR Fostex 127E but they just don't have any bass, I don't know where to look for info on modest budget horn setups.
For those interested in simulating their designs with SPICE, I developed a slightly refined DHT composite model using my own set of curves. A model is available for PSE as well.
Difference is on KP parameter which drives linearity of the model. With Dmitry's model you get a slightly worse THD response when swinging the 4P1L to its limits.
4P1L triode SPICE model | Bartola Valves
Hope this helps
Ale
Difference is on KP parameter which drives linearity of the model. With Dmitry's model you get a slightly worse THD response when swinging the 4P1L to its limits.
4P1L triode SPICE model | Bartola Valves
Hope this helps
Ale
Thanks Ale. As I mentioned before, if you ever find the time to trace the 26 would be great. Dmitry's model of the 26 I think is based on the datasheet, not a working sample.
No pressure, just saying, maybe one day. You've already helped a great number of us with your experiments.
Could I use 3 resistor of 47R like these https://es.rs-online.com/web/p/resistencias-fijas-de-orificio-pasante/1995937/ in parallel as cathode resistor?
How many mA have I to set the CCS?
How many mA have I to set the CCS?
Attachments
Those resistors should give you around 15R at 36W. Close enough for jazz.
If you are using glow tubes, it's useful to read the instructions for using them.
http://www.mif.pg.gda.pl/homepages/frank/sheets/141/g/GL874.pdf
You will see that for the octal glow tubes they need 22.5mA and the 7 pin ones need 17.5v. Subtract the minimum current from the maximum current and divide by two. Then add that to the minimum current. So for 0D3 max is 40mA, min is 5mA. Difference = 35mA. Half of that is 17.5V. Add that to the minimum 5v and you have 22.5v. For the 7 pins the max voltage is 30v, so current you need is 17.5mA. That is true of all glow tubes of these types.
So what you then do is add the current through the glow tube to the current through the tube(s) you are using. For 2 x 4P1L at 36mA, add 22.5v and you set the DN2540 for 58.5mA.
If you are using glow tubes, it's useful to read the instructions for using them.
http://www.mif.pg.gda.pl/homepages/frank/sheets/141/g/GL874.pdf
You will see that for the octal glow tubes they need 22.5mA and the 7 pin ones need 17.5v. Subtract the minimum current from the maximum current and divide by two. Then add that to the minimum current. So for 0D3 max is 40mA, min is 5mA. Difference = 35mA. Half of that is 17.5V. Add that to the minimum 5v and you have 22.5v. For the 7 pins the max voltage is 30v, so current you need is 17.5mA. That is true of all glow tubes of these types.
So what you then do is add the current through the glow tube to the current through the tube(s) you are using. For 2 x 4P1L at 36mA, add 22.5v and you set the DN2540 for 58.5mA.
It's difficult to say if I prefer 4P1L or 26, because my amp is 4P1L into PSE 4P1L. Three stages of 4P1L are too much, so I'm using a 26 preamp. I'm going to try the 10Y next - I made a 10Y preamp before and preferred 26, but the 10Y wasn't optimised.
For a 4P1L preamp you need to do something about microphonics. Here's my latest idea using 1.5" plumbing parts. The brass parts don't touch the top plate - the rubber washers come in between, top and bottom. The tube socket is held between the two screwed pipes. I haven't tried it yet - should work! It's pretty heavy.....
Andy
For a 4P1L preamp you need to do something about microphonics. Here's my latest idea using 1.5" plumbing parts. The brass parts don't touch the top plate - the rubber washers come in between, top and bottom. The tube socket is held between the two screwed pipes. I haven't tried it yet - should work! It's pretty heavy.....
Andy
Attachments
Clever idea! I gave up on the 4P1L in preamp or input mode, just couldn't beat the microphonics. Let us know how this works out.
Even though I don't believe much in huge differences in sound between tubes of the same model, I am curious if anyone compared the Russian 4P1L with the similar Chinese 4P1S. How do they compare? Are they indeed similar and therefore interchageable?
Many thanks, Erik
Many thanks, Erik
Hi Andy,
I am leaning towards the 4P1L-IS-4P1L-IS concept myself to drive a 300B.
I guess the first tube is the most problematic considering microphonics. Is it the vibrations passed on via the case or air vibrations which are the most problematic?
What is your latest anti microphonics solution?
Thanks,
Peter