>We found a big difference making this cap a poly one.
Do you have experience with this circuit, in this amp?
Do you have experience with this circuit, in this amp?
It doesn't matter really! The last PSU cap is for SURE in the signal path. Class A is the best case scenario but still not perfect.
Electrolytics caps are leaky and lossy, more than any other. Very good as resevoirs but bad for filtering.
Yes, the Grant Fidelity RITA has the same topology, with a paraphase splitter > LTP > UL output stage. It made a significant difference modifying the 1st stage to a CSS loaded LTP.
dave
...sorry, but just because you might have fixed some Chinese Yaquin push-pull, doesn't mean you have experience with this amp. Suggesting modifications "that significantly improve it" before even listening to it has the same value as suggesting more salt by looking at a picture of a soup.
It is the same circuit. ParaPhase spliters are from the dark ages. And the poly as the last filter cap to keep the signal path clear of elcos is well established.
dave
dave
Ok, let´s see, here we have a circuit with a well known topology. Many people can judge the audible merits just by looking at the shematics. Pharaphase splitter, ok, can be good, BUT nowadays that´s been superseeded with LTP.
NO bad circuit can be salvaged by throwing in the most costly parts available 🙂
And the notion that polymer caps can be formed or bettered by time, that is utter BS. What happen is, that your ear becomes accustomed to the sound, not that "some" part changes it´s properties. Your ear is much more customisable than any of your gear (in small propotions)
NO bad circuit can be salvaged by throwing in the most costly parts available 🙂
And the notion that polymer caps can be formed or bettered by time, that is utter BS. What happen is, that your ear becomes accustomed to the sound, not that "some" part changes it´s properties. Your ear is much more customisable than any of your gear (in small propotions)
Clearly your builder's pride is showing, tube amplifier designs are donkey's years old - there is nothing special about the Edison 60, anyone with basic electronics knowledge can analyse it and assess its merit notwithstanding your protestations.
>What happen is, that your ear becomes accustomed to the sound,
Yes, that's why the scope traces look so different, because my ears got accustomed to sound.
Yes, that's why the scope traces look so different, because my ears got accustomed to sound.
fb2017, you wrote in you starter post:
As things are going my feeling is that you just want to show off because if someone does have a differet opinion then it's not good, without realizing that your amp is nothing special.
Actually not just opinion but undeniable facts like PSU capacitors in the signal path that you had no idea of. Make peace with yourself first.
and then
As things are going my feeling is that you just want to show off because if someone does have a differet opinion then it's not good, without realizing that your amp is nothing special.
Actually not just opinion but undeniable facts like PSU capacitors in the signal path that you had no idea of. Make peace with yourself first.
Electroharmonix EL34 vs Genalex Golden Lion KT77
This has been probably discussed quite often here, but I would still like to open a new thread on it. After about 1200 hour the Electroharmonix EL34EH tubes in my Audion Edison 60 amp (class A) are showing signs of fatigue, with one particular tube generating a lot of short bursts of white noise in the warm up phase. By exchanging the tubes, I could exactly identify the culprit.
Questions:
1 - Should I change only this one, or just replace the set of quad altogether.
2 - Many reviewers online seem to strongly recommend the Golden Lion KT77. It is twice as expensive as the EL34EH. Will it last twice as long as well, or does it only sound twice as good? Or is it neither? As I am using the amp with fullrange speaker, a bit more bass is always welcome, but NOT at the expense of midrange clarity, where my setup is hard to beat, IMHO.
This has been probably discussed quite often here, but I would still like to open a new thread on it. After about 1200 hour the Electroharmonix EL34EH tubes in my Audion Edison 60 amp (class A) are showing signs of fatigue, with one particular tube generating a lot of short bursts of white noise in the warm up phase. By exchanging the tubes, I could exactly identify the culprit.
Questions:
1 - Should I change only this one, or just replace the set of quad altogether.
2 - Many reviewers online seem to strongly recommend the Golden Lion KT77. It is twice as expensive as the EL34EH. Will it last twice as long as well, or does it only sound twice as good? Or is it neither? As I am using the amp with fullrange speaker, a bit more bass is always welcome, but NOT at the expense of midrange clarity, where my setup is hard to beat, IMHO.
EL34 6CA7 CV1741 KT77 are all equivalents to each other. The EL34 was the 1952 successor to the very successful EL37 and both share a high value of mutual conductance 11.0 mA/V. The EL37 was of pinch construction whereas for the EL34 Mullard used the pressed glass foot construction employed on the B9A and B7G miniature valves for this IO based device.
Answering the original post, yes you should replace the whole quad. Maybe you can keep one pair as spares, but they're likely to go south soon.
Now, there's a good crop of current manufacture EL34 variants to choose from. My personal favourites have been the JJ EL34, JJ KT77 and "Gold Lion" KT77 (the New Sensor "re-issue"). And if NOS tubes were included, the RFT/Siemens EL34 is really great, I think even better than Mullard, but they too have a hard time justifying their price. But YMMV, since some tubes work in some amps, and other tubes in other amps...
Anyhow, in all the EL34 amps I've had, the JJ EL34 is so close to the original Mullard EL34 that I see no point in paying through the nose for the latter. You get a bigger difference by switching to beam tubes like the KT77 or 6CA7.
Now, there's a good crop of current manufacture EL34 variants to choose from. My personal favourites have been the JJ EL34, JJ KT77 and "Gold Lion" KT77 (the New Sensor "re-issue"). And if NOS tubes were included, the RFT/Siemens EL34 is really great, I think even better than Mullard, but they too have a hard time justifying their price. But YMMV, since some tubes work in some amps, and other tubes in other amps...
Anyhow, in all the EL34 amps I've had, the JJ EL34 is so close to the original Mullard EL34 that I see no point in paying through the nose for the latter. You get a bigger difference by switching to beam tubes like the KT77 or 6CA7.
I agree on the JJ KT77s. I switch my Dyna. ST-70 to them for the advantage of much higher screen grid voltage rating. They work very well, about 100 hours so far without a hitch.
If you have ANY amplifier that is wired exclusively for KT77 tubes, then do not use any EL34 or 6CA7 Until you do one thing . . . Connect Pin 1 on the socket to Pin 8 on the socket.
If you do not, then the EL34 and 6CA7 will have a floating suppressor grid.
By the way, the 6CA7 and EL34 originally were 'Pentode' Tubes (with a real suppressor grid). The KT77 was originally a 'Beam Tetrode' Tube or 'Beam Pentode' Tube (with a real Beam Forming Element).
What manufacturers choose to do with regards to honoring the original designs, is up to them, and up to those who choose to check whether the original design has been adhered to before purchasing them.
All equivalent tubes are created equal, but some equivalent tubes are created more equal than others (reference George Orwell).
I like my JJ KT77 tubes. My JJ vendor, Eurotubes does a lot of additional testing on the tubes before they are sold.
If you do not, then the EL34 and 6CA7 will have a floating suppressor grid.
By the way, the 6CA7 and EL34 originally were 'Pentode' Tubes (with a real suppressor grid). The KT77 was originally a 'Beam Tetrode' Tube or 'Beam Pentode' Tube (with a real Beam Forming Element).
What manufacturers choose to do with regards to honoring the original designs, is up to them, and up to those who choose to check whether the original design has been adhered to before purchasing them.
All equivalent tubes are created equal, but some equivalent tubes are created more equal than others (reference George Orwell).
I like my JJ KT77 tubes. My JJ vendor, Eurotubes does a lot of additional testing on the tubes before they are sold.
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Thank you or all the answers. Here is the schematic of the amp, the pin 1 is already connected to pin 8 (originally came with EL34EH), and its an autobias.
In your opinion, how is the bass on the JJ KT77 vs EL34EH (and vs. golden Lion KT77, if somebody tried both)?
I'd like to increase the bass a bit, without additional resistors in my full range Dallas II.
In your opinion, how is the bass on the JJ KT77 vs EL34EH (and vs. golden Lion KT77, if somebody tried both)?
I'd like to increase the bass a bit, without additional resistors in my full range Dallas II.
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