Hi Zoran,
If you only knew how often the phase can be reversed in the studio and in mixing. Personally I can not reliably detect phase. Maybe with some music, but not enough to go through my LP's and CD's to mark absolute phase on each one.
Absolute phase has people worried over something they can not always control. You really ought to be listening to the music. My bench is downstairs, not in my living room.
Hey Positron,
I think we get it. The 6922 can sound pretty good. So can the 6SN7, 6SL7 and a ton of other tubes.
One thing I can say for sure. Preamps that measure well and sound good are better than ones that do not measure well and sound "good". Usually there are very high levels of D2 that could have been avoided. Once you get a grip on what orders of THD are okay at what levels, you can balance other things off in your design. I have a feeling you know all of this. Understand I've alluded to the fact that the distortion products are just as important as the numbers.
Cheers, -Chris
If you only knew how often the phase can be reversed in the studio and in mixing. Personally I can not reliably detect phase. Maybe with some music, but not enough to go through my LP's and CD's to mark absolute phase on each one.
Absolute phase has people worried over something they can not always control. You really ought to be listening to the music. My bench is downstairs, not in my living room.
Hey Positron,
I think we get it. The 6922 can sound pretty good. So can the 6SN7, 6SL7 and a ton of other tubes.
One thing I can say for sure. Preamps that measure well and sound good are better than ones that do not measure well and sound "good". Usually there are very high levels of D2 that could have been avoided. Once you get a grip on what orders of THD are okay at what levels, you can balance other things off in your design. I have a feeling you know all of this. Understand I've alluded to the fact that the distortion products are just as important as the numbers.
Cheers, -Chris
Hi,
I just want to point the way how it should be done the proper design...
I didnt ment enything bad at all sorry...
Simple rule is that phase at the input of the any device should be the same at the output.
We want correct reproduction, regardless the possibile mistakes done in the recording process, that is another question.
Inverting the phase on speaker does not work, please make a simple try.
Maybe the arrangement of interconnect cables can help in this, when we taljk about valve preamps story, typical example...
for every chanel we need 2x sheilded cable, two sheilds merged and connected to chasis
ground point, signal and audio ground goes to each separate lines... The merged sheilds are not connected at the other side of cable (input of the amplifier). That is a sort of chassis extension...
If the amplifier is tube type, it should be done a check of phase and if there is a need invert the phase on the output transformer secondary...
for instance typical tube SE power amplifier of 2 stages deserves to shift pahase at the OT for standard compatibile mode of use with other also standard devices with same pahase in and out... But with most common preamps designs like we have here we have to swithch the phase on the secondary end. And apply the interconnect cables arrangement too...
I just want to point the way how it should be done the proper design...
I didnt ment enything bad at all sorry...
Simple rule is that phase at the input of the any device should be the same at the output.
We want correct reproduction, regardless the possibile mistakes done in the recording process, that is another question.
Inverting the phase on speaker does not work, please make a simple try.
Maybe the arrangement of interconnect cables can help in this, when we taljk about valve preamps story, typical example...
for every chanel we need 2x sheilded cable, two sheilds merged and connected to chasis
ground point, signal and audio ground goes to each separate lines... The merged sheilds are not connected at the other side of cable (input of the amplifier). That is a sort of chassis extension...
If the amplifier is tube type, it should be done a check of phase and if there is a need invert the phase on the output transformer secondary...
for instance typical tube SE power amplifier of 2 stages deserves to shift pahase at the OT for standard compatibile mode of use with other also standard devices with same pahase in and out... But with most common preamps designs like we have here we have to swithch the phase on the secondary end. And apply the interconnect cables arrangement too...
I assume you mean "polarity," not phase, but in an case, of course it works. If polarity is reversed an odd number of times, it will end up reversed. An even number of times, the polarity will be unchanged. Period.
Hi Stuart,
There is confusion between phase and polarity. 180° out of phase = reversed polarity.
-Chris
Yes. Every single time, without fail. This works with marked string as well.
There is confusion between phase and polarity. 180° out of phase = reversed polarity.
-Chris
Phase is a way of expressing delay that shows whether it is significant at the frequency concerned. The only time that 180° of phase can be confused with polarity inversion is when a single measurement is made using a sine wave. Polarity and phase really are quite different.
Hi EC8010,
There has been a significant loosening of terms by the time I was educated. Pity.
Normally (like the "new math") there is no information about the beginning of the signal (an no stipulation that phase can only be lagging) so that at 180 °, reversing polarity would be indistinguishable from a phase shift. I will accept your definition simply because in reality, a lag is all that is possible when compared to the source.
-Chris
There has been a significant loosening of terms by the time I was educated. Pity.
Normally (like the "new math") there is no information about the beginning of the signal (an no stipulation that phase can only be lagging) so that at 180 °, reversing polarity would be indistinguishable from a phase shift. I will accept your definition simply because in reality, a lag is all that is possible when compared to the source.
-Chris
Years ago, I used to make phase measurements of stereo audio circuits then fit a compensating delay equaliser. Later, I became involved with analogue PAL and colour subcarrier phase relationships. It's make me a little pernickety about phase and polarity.
Hi EC8010,
-Chris 😉
For good reason from what I know of those things. No argument from me, right is right.
-Chris 😉
SY said:
On paper a 6es8 looks fine for use with a ccs of 10 mA and a grid bias of -2 V. Has anyone tried this? Something like the hybrid version in 4 aug's tubecad blog?
You're no doubt right and I'm not trying to be argumentative, but I don't understand. At 10 mA I read:
1 V - 70 V
2 V - 98 V
3 V - 126 V
Doesn't that mean it's pretty linear?
Henk
1 V - 70 V
2 V - 98 V
3 V - 126 V
Doesn't that mean it's pretty linear?
Henk
It actually helps to set one up and measure it, but let's go with the curves. We'll pick a slightly smaller swing but at the same points.
At 10mA:
-1V 70V
-1.5V 86V
-2V 98V
Variable mu in action.
At 10mA:
-1V 70V
-1.5V 86V
-2V 98V
Variable mu in action.
A mystery?
I can't imagine hearing a difference between 150kHZ and 200kHZ -1dB BW period. But, what might be going on here (that I just read about in the Morgan Jones book) is that the self inductance of MM cartridges is often designed to work with the loading capacitance to create a slight extension of the otherwise drooping high end response. It forms a resonant circuit, much like a bass reflex speaker does at the low end. But if the capacitance is off at all, the result can be pretty damaging, and possibly cause psyco-acoustic effects all across the spectrum.
A mystery
A couple of areas could cause this. First, though, the equalization is not located such that cartridge loading was affected.
Second, a change in overall system risetime occurs which the ear is sensitive too. Jneutron (FermiLab, Brookhaven National Laboratory) has posted information concerning this subject on AVS forum some time ago, and Dr. Kunkur published his research a couple of years ago. Third, Japanese research, using PET and EEG scans has also measured (through ear/brain's activity and not bone conduction) ultra sonic musical stimuli between 22khz and approx. 50khz, the high frequency limit of the test.
Cheers.
A couple of areas could cause this. First, though, the equalization is not located such that cartridge loading was affected.
Second, a change in overall system risetime occurs which the ear is sensitive too. Jneutron (FermiLab, Brookhaven National Laboratory) has posted information concerning this subject on AVS forum some time ago, and Dr. Kunkur published his research a couple of years ago. Third, Japanese research, using PET and EEG scans has also measured (through ear/brain's activity and not bone conduction) ultra sonic musical stimuli between 22khz and approx. 50khz, the high frequency limit of the test.
Cheers.
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I found this doing a search as I am using a 6J5 as the amplifier in a SE 6V6 amp. The 6J5 6SN7 are directly descended from the 27 triode that was used in thousands of radios just by itself. The 6SN7 itself has been made since the late 30s and some of the best are the ones made in WWII, probably by the hands of women, using chemicals that can only be used in China who is trading their environment in a bid to own the agriculture lands of the world, since theirs is already ruined. Sorry, I shouldn't say a thing, but the fact is that this tube has been in production for longer than most people with good health care live. It is a rugged tube and has a thousand flavors. With the Hickock Cardomatic tester there are 2 tests, one per side.
6DJ8s on the other hand use 4 cards and have 8 tests and most fail, and most of the ones that don't sound like electric turds. The fact is that they are easy to design around and a good pair of NOS Amperex 7308s will cost as much as an exellent pair of power triodes and probably won't last near as long.
I pulled a bunch out of some old TeK O'scopes and even the ruggedized GE Mil Specs had about a 75% fail rate, the Amperex BB had about a 5% pass rate and those were replacement tubes put in during an overhaul of the scope. They have a place but I will never buy anything that has one in it, I will never build anything that has one in it. They have too many things that WILL go wrong with them, a good sounding pair will run a good $250 for NOS JAN Amperex 7308s and VT-231s are some of the best dual triodes ever built and you can run them for years and they will still sound great, test strong and the fail rate is way down there.
I have the slightly higher gain 6SL7s driving 300Bs and the RCA VT-229s have been in there 8 years and still out perform any other 6SL7s I have tried. They probably had thousands of hours on them when I got them. The stuff made in WWII for the Boys was and is the best of the dual triodes you can use to amplify a CDP directly to the power tubes.
Then you have the 100s of other very good ones made all over the world, and are still being made today.
Dollar for dollar the money spent on a 6SN7, 6J5, 6C5, 70 , 27 will get you more for less than the 6DJ8 family of high failure rate, mostly not very good sounding, easy to use in designs, tubes.
You want to find out about tubes talk to anybody who tests a lot of them as well as listens to them.
There are always going to be some of any kind of audio tube that is great, but if you put down $250 for a pair of dual triodes, don't you want them to last for as long as you want to listen to them?
Having to scrounge and get old gear for pulls a failure rate of 75% vs 5% says more about build quality of a type than almost anything else.
Most of my 6V6s are RCAGTs with the graphite inside that came out of Hammond organs built in the 40s and I think that the average test on those was 75 out of 100, failure rate about 3%. That is better than fair.
Thatch
6DJ8s on the other hand use 4 cards and have 8 tests and most fail, and most of the ones that don't sound like electric turds. The fact is that they are easy to design around and a good pair of NOS Amperex 7308s will cost as much as an exellent pair of power triodes and probably won't last near as long.
I pulled a bunch out of some old TeK O'scopes and even the ruggedized GE Mil Specs had about a 75% fail rate, the Amperex BB had about a 5% pass rate and those were replacement tubes put in during an overhaul of the scope. They have a place but I will never buy anything that has one in it, I will never build anything that has one in it. They have too many things that WILL go wrong with them, a good sounding pair will run a good $250 for NOS JAN Amperex 7308s and VT-231s are some of the best dual triodes ever built and you can run them for years and they will still sound great, test strong and the fail rate is way down there.
I have the slightly higher gain 6SL7s driving 300Bs and the RCA VT-229s have been in there 8 years and still out perform any other 6SL7s I have tried. They probably had thousands of hours on them when I got them. The stuff made in WWII for the Boys was and is the best of the dual triodes you can use to amplify a CDP directly to the power tubes.
Then you have the 100s of other very good ones made all over the world, and are still being made today.
Dollar for dollar the money spent on a 6SN7, 6J5, 6C5, 70 , 27 will get you more for less than the 6DJ8 family of high failure rate, mostly not very good sounding, easy to use in designs, tubes.
You want to find out about tubes talk to anybody who tests a lot of them as well as listens to them.
There are always going to be some of any kind of audio tube that is great, but if you put down $250 for a pair of dual triodes, don't you want them to last for as long as you want to listen to them?
Having to scrounge and get old gear for pulls a failure rate of 75% vs 5% says more about build quality of a type than almost anything else.
Most of my 6V6s are RCAGTs with the graphite inside that came out of Hammond organs built in the 40s and I think that the average test on those was 75 out of 100, failure rate about 3%. That is better than fair.
Thatch
Thatch, I've heard that a lot of 6DJ8's are noisy as well. In my present preamp design I'm using one 6922 and one 6SN7 for voltage gains (so have different ring frequencies if that's an issue), and 6922 for follower output buffers (the high transconductance makes them better), all with current sources. The voltage gain stages will have Gary Pimm I sources with their "mu" outputs, so the stage becomes a mu follower if I'm not mistaken. I've looked at the distortion spectrum shape to see if putting the Gary Pimm FETs in the circuit do any damage. They did no damage at all. A self biased follower with a IXYS constant current sink also has the very best of distortion spectrum shape (output buffers). You can Google Gary Pimm to learn more about his self powered CCS if interested. Using the low-Z "mu" output reduces noise in the following passive tone control circuit (James). This seems like the best route to go for a line level preamp with tone controls. Minimalist, but not lacking anything desirable.
its common knowledge . that a mini can NEVER be that good as a octal
course in miniaturization the linearity is sacrificed .
plus WHY would you put anything in a amp that does not glow as pretty as a 6sn7 ?
course really 6dj8 is no audio tube . 😛
course in miniaturization the linearity is sacrificed .
plus WHY would you put anything in a amp that does not glow as pretty as a 6sn7 ?
course really 6dj8 is no audio tube . 😛
i just like the 6sn7 and dislike the mini hero 6dj8
QUOTE .
The age of tube developments has ended around 1936. it was just further refinement and miniaturization. Even miniaturization was often done at the costs of good tube curves. Of course many famous tubes were made after 1935, but the real kings and queens are from before that date.
no offense but i think its pretty bad people are spending small fortunes on scope pull 6dj8
while there is so much choice .
edit please . if im wrong educate me .
you learn from being embarrassed .
QUOTE .
The age of tube developments has ended around 1936. it was just further refinement and miniaturization. Even miniaturization was often done at the costs of good tube curves. Of course many famous tubes were made after 1935, but the real kings and queens are from before that date.
no offense but i think its pretty bad people are spending small fortunes on scope pull 6dj8
while there is so much choice .
edit please . if im wrong educate me .
you learn from being embarrassed .
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