I measured the output of the amplifier for musical loads,
I measured peaks of 8 Vrms, and 0.8 Arms
I will receive mono SS amplifiers in a few weeks to compare the sound, it is the most clear and detailed amplifier....
I measured peaks of 8 Vrms, and 0.8 Arms
I will receive mono SS amplifiers in a few weeks to compare the sound, it is the most clear and detailed amplifier....
Ouch I compared the amplifier to a SS amplifier of around same power and the SS has more resolution.
Both sound completely different while being very faithful to the music and with no fatigue.
The SS sound lush, with depth and outer detail which is totally lacking in the tube design despite the highest resolution that I could attain.
Due to being able to hear each movement of the tongue and breath the SS amp has more emotion, just pure 3d sounds like a real concert hall, the tube presents a wall, the SS presents a theater.
I still use a tube-pre and a tube buffer based on AK4396.
Opened to suggestions for the tube amp, how to make the sound holographic. This pentode CFB has the most resolution that I could achieve, the new transformers opened doors. But for my audiophile speakers it just doesn't match the hifi amps...
I had 2 other SS amps and my new one is just way above. Keep pushing, never surrender and open the doors of sound pleasures!!!
Both sound completely different while being very faithful to the music and with no fatigue.
The SS sound lush, with depth and outer detail which is totally lacking in the tube design despite the highest resolution that I could attain.
Due to being able to hear each movement of the tongue and breath the SS amp has more emotion, just pure 3d sounds like a real concert hall, the tube presents a wall, the SS presents a theater.
I still use a tube-pre and a tube buffer based on AK4396.
Opened to suggestions for the tube amp, how to make the sound holographic. This pentode CFB has the most resolution that I could achieve, the new transformers opened doors. But for my audiophile speakers it just doesn't match the hifi amps...
I had 2 other SS amps and my new one is just way above. Keep pushing, never surrender and open the doors of sound pleasures!!!
This weekend will be a busy one.
I am testing the amplifier with CF removed and on in both channels to confirm wiring is done properly and measure the impact on the sound.
As one friend here suggested that triode is way superior, maybe it wasn't satisfactory on other design with less performing output transformers and that I may reconcile with its sweet sound on this prototype (and a nice one).
I will place it in triode mode which is easy by disconnecting the screen supplies and inserting the 100R.
I will have both a listening test and a THD test.
If anyone requires some tests and want to know more about effect of Pentode with and without CF.
And Triodes mode kt88 with CF and without this is YOUR opportunity!!!
I can do sweeps, intermodulation and arbitrary waves, and I can also show the difference with a SS amplifier to find where the tube amp 'failed' at almost everything.
I am testing the amplifier with CF removed and on in both channels to confirm wiring is done properly and measure the impact on the sound.
As one friend here suggested that triode is way superior, maybe it wasn't satisfactory on other design with less performing output transformers and that I may reconcile with its sweet sound on this prototype (and a nice one).
I will place it in triode mode which is easy by disconnecting the screen supplies and inserting the 100R.
I will have both a listening test and a THD test.
If anyone requires some tests and want to know more about effect of Pentode with and without CF.
And Triodes mode kt88 with CF and without this is YOUR opportunity!!!
I can do sweeps, intermodulation and arbitrary waves, and I can also show the difference with a SS amplifier to find where the tube amp 'failed' at almost everything.
Hi Svytoslav, I don't understand the question...
the circuit is variable as you can tell. I liked the kt120 ultralinear with 6sn7 gain and ecc99 phase splitter LTP.
I don't know if it matters but now it is 6sl7 gain and paraphrase. this is directly coupled to 6sn7 Cathode followers.
I preferred a lot Pentode CF to ultralinear.
the circuit is variable as you can tell. I liked the kt120 ultralinear with 6sn7 gain and ecc99 phase splitter LTP.
I don't know if it matters but now it is 6sl7 gain and paraphrase. this is directly coupled to 6sn7 Cathode followers.
I preferred a lot Pentode CF to ultralinear.
because it sounds so poor vs my transistor amplifier I will see if the CF works properly and then proceed to convert it to Triode CF and see if I can gain something using CF in triode.
In triode it is worse than Ultralinear, it lacks details a lot and the sound is way too round.
In triode it is worse than Ultralinear, it lacks details a lot and the sound is way too round.
my transistor amplifier is really looking like nothing but it trash out all my tube amplifiers.
I did not see any difference with two 2.5 Watts signals sent together. No difference in Pentode CF or No CF
Maybe if I reversed the output Ground and signal maybe it means my CF is not working as intended???
Something might be wrong because the CF or not it makes no difference at all. there is maybe 0.5 db improvement in distortion only...
Something is fishy there.
Something is fishy there.
Today it is total madness I installed new WTB rhodium RCA females on the DAC and wired with BL-1 DH labs wires with upgraded bullet RCA its a very costly upgrade and I rewired my loudspeakers, the difference is MAJOR.
I used to have Belkin and Pure AV interconnects and generic gold plated RCA ... this is massive
I used to have Belkin and Pure AV interconnects and generic gold plated RCA ... this is massive
I reversed the polarity of the output and everything else, including cathode feedback on one channel... and converted the amp one side to Triode.
Tomorrow I power up and adjust the bias, then proceed to reduce splitter distortion then take measurement in triode with CF and without CF. And also i will measure the output impedance if there is any difference....!!!!!!!!!!!!!!!!!!
Tomorrow I power up and adjust the bias, then proceed to reduce splitter distortion then take measurement in triode with CF and without CF. And also i will measure the output impedance if there is any difference....!!!!!!!!!!!!!!!!!!
I connected Triode , the impedance dropped to 1.5R , it is 2R in pentode.
But THD figures are way way worse, it is not even funny, now lets reconnect the CF and see if it makes any difference in Zout.
But THD figures are way way worse, it is not even funny, now lets reconnect the CF and see if it makes any difference in Zout.
I installed 500ma fuses to make sure to bypass the CF windings , the 250ma Fused were all gone probably due to soldering heat. So the test above is WITH CF. Now I am measuring the Zout without CF.
Z out in Pentode is 1R and 2R with CF, which should be the opposite.
Zout in triode is 1.4R and rising slightly in frequency with CF, without CF it is stable 1.4R and decreasing in frequency.
Could it be that the CF windings are reversed in each tube and that I am injecting positive feedback at the cathodes of the tubes????
With the CF the sensitivity of the amplifier is increased a lot. for example I have a reading of 0.43 mV out , and when I disconnect the CF the output drops to 0.229
So I think I can reverse the Cathodes wires in each tube , I hope it doesn't cause an oscillation
Zout in triode is 1.4R and rising slightly in frequency with CF, without CF it is stable 1.4R and decreasing in frequency.
Could it be that the CF windings are reversed in each tube and that I am injecting positive feedback at the cathodes of the tubes????
With the CF the sensitivity of the amplifier is increased a lot. for example I have a reading of 0.43 mV out , and when I disconnect the CF the output drops to 0.229
So I think I can reverse the Cathodes wires in each tube , I hope it doesn't cause an oscillation
A 500Watts class D, just joking, they are single channel, I will not say because I doubt anyone here listened to it.
You might take a wild guess 😉 they are far from perfect, however they give me what I want. and in my 'book' they are the best for my taste.
You might take a wild guess 😉 they are far from perfect, however they give me what I want. and in my 'book' they are the best for my taste.
I converted on the triode side at only 5.5 Watts I have 0.45% THD, this is a lot, now let see what happened to the output impedance... with the CF reversed.
I reversed the CF in the triode channel, and I didn't took detail THD yet or anything,
The output impedance went up to 4R, so it seems the CF is working fine.
Maybe it is fighting with the 10R bias resistor? So it seems the amplifier function better in Pentode without CF
The output impedance went up to 4R, so it seems the CF is working fine.
Maybe it is fighting with the 10R bias resistor? So it seems the amplifier function better in Pentode without CF