The GE data state that the medium-mu section of this type is rated at 1W Pa.
Has anyone experience of running 6DN7?
I ask because it is obvious that the anode is well capable of handling at least 2W, so I assume that the 1W rating referred to line-oscillator service.
Has anyone any more information about this?
Many thanks
7N7
Has anyone experience of running 6DN7?
I ask because it is obvious that the anode is well capable of handling at least 2W, so I assume that the 1W rating referred to line-oscillator service.
Has anyone any more information about this?
Many thanks
7N7
6DN7
Hi,
Guilty.
The reason for the max diss. of 1W has more to do with the fact that if you use section 2 as well it will inevitably heat up section 1.
You can push section 1 provided you don't use section 2 simultaneously.
Cheers,😉
Hi,
Guilty.
The reason for the max diss. of 1W has more to do with the fact that if you use section 2 as well it will inevitably heat up section 1.
You can push section 1 provided you don't use section 2 simultaneously.
Cheers,😉
Re: 6DN7
I have tested Section I for distortion and certain examples are very good. I would use section II proabably as a cathode follower and not run it anywhere near its rated Pa, so I think I should be able to get away with a bit more! 😉
7N7
fdegrove said:
I have tested Section I for distortion and certain examples are very good. I would use section II proabably as a cathode follower and not run it anywhere near its rated Pa, so I think I should be able to get away with a bit more! 😉
7N7
PUSHING THINGS.
Hi,
Under those conditions you may well be able to get away with it.
If sound is important do you try the black (graphite) plates,they exhibit less 4th and 6th harmonic distortion artifacts.
Cheers,😉
Hi,
Under those conditions you may well be able to get away with it.
If sound is important do you try the black (graphite) plates,they exhibit less 4th and 6th harmonic distortion artifacts.
Cheers,😉
Re: PUSHING THINGS.
I have just reviewed my results from the eight that I tested. The two that gave the lowest THD did in fact have black anodes; however one of the worst had black anodes too!
However I test up to 6th harmonic, and all of them gave good results - in fact I think most of the distoriton came from the oscillator. My oscillator's THD is -64dB, at pretyy much all levels and the levels of upper harmonics are consistent too.
I tested 6DN7 at +22dB output (9.7v rms), +28dB (19.8v rms) and +32 dB (30.8v rms); at +32dB which is a silly level really, the best examples showed THD of about 0.08% whilst the worst showed 0.34%! With variance like this, I shall test them all very carefully (I have some more coming). However at +22dB, things settled down a bit and the worst was a little over 0.1% whilst the best was just under 0.07%.
A very good feature is the generally low levels of fourth harmonic and above - typically -82+dB =0.008% at + 22dB output - this is obviously what is coming from the oscillator, so I think that 6DN7 - section I anyway - would make fine differential pairs - even 3rd harmonic was generally about -80dB - again much of which was coming from the oscillator.
Best wishes
7N7
fdegrove said:
I have just reviewed my results from the eight that I tested. The two that gave the lowest THD did in fact have black anodes; however one of the worst had black anodes too!
However I test up to 6th harmonic, and all of them gave good results - in fact I think most of the distoriton came from the oscillator. My oscillator's THD is -64dB, at pretyy much all levels and the levels of upper harmonics are consistent too.
I tested 6DN7 at +22dB output (9.7v rms), +28dB (19.8v rms) and +32 dB (30.8v rms); at +32dB which is a silly level really, the best examples showed THD of about 0.08% whilst the worst showed 0.34%! With variance like this, I shall test them all very carefully (I have some more coming). However at +22dB, things settled down a bit and the worst was a little over 0.1% whilst the best was just under 0.07%.
A very good feature is the generally low levels of fourth harmonic and above - typically -82+dB =0.008% at + 22dB output - this is obviously what is coming from the oscillator, so I think that 6DN7 - section I anyway - would make fine differential pairs - even 3rd harmonic was generally about -80dB - again much of which was coming from the oscillator.
Best wishes
7N7
SMALL WARNING.
Hi,
This is just a word of caution,not to you as such, but in general.
When going for "odd ball" valves like this family,you have to be sure that they're not rejects from someone else's trials.
You'd be surprised to learn how many times the average valve travels around the globe.
Your measurements seem acceptable though...
Cheers to you too,😉
Hi,
This is just a word of caution,not to you as such, but in general.
When going for "odd ball" valves like this family,you have to be sure that they're not rejects from someone else's trials.
You'd be surprised to learn how many times the average valve travels around the globe.
Your measurements seem acceptable though...
Cheers to you too,😉
Re: SMALL WARNING.
Good point, and one to bear in mind. Perhaps all that travelling matures them like Madeira wine that was sent round Cape Horn?
fdegrove said:
Good point, and one to bear in mind. Perhaps all that travelling matures them like Madeira wine that was sent round Cape Horn?
... hm, so you think that my 6DN7's might have already seen Cape Horn ?! 
Serious, like the black plate 6DN's very much. Drive my 6C33C-SE with them, they make a good driver with their low Rp for the grid capacities of the big russian glass...
Marcus
Serious, like the black plate 6DN's very much. Drive my 6C33C-SE with them, they make a good driver with their low Rp for the grid capacities of the big russian glass...Marcus
My 6DN7 journey
First of all, hello everybody!
My first post here, I did build many tube amp's for my self and for
other that did ask me, I am from Norway, but I am retired now and
moved to the Philippnes. So I start to build amplifiers, again.
Some years ago I did build this 6DN7 on a wooden frame,
when I was living in London, but this one is long time gone...
It did sound very sweet and nice, and not that expensive and
not difficult to build, so later I build another one on a scrap chassis.
Same sweet sound, surprising deep and clear bass, the OPT is not
that big. It looks like crap so I decided to rebuild it, on a new chassis.
This is the red one you see, just started today.
I use 2 U shape canals, that will shield the "AC part" in the back from
the signal part in the front.
I am using lundahl horn speakers, the 1 - 2 watt drive the horn speaker
without problem, my wife start to complain about half volume.
This amplifier is well worth trying out, you will not regret it.
Jogeir.
First of all, hello everybody!
My first post here, I did build many tube amp's for my self and for
other that did ask me, I am from Norway, but I am retired now and
moved to the Philippnes. So I start to build amplifiers, again.
Some years ago I did build this 6DN7 on a wooden frame,
when I was living in London, but this one is long time gone...
It did sound very sweet and nice, and not that expensive and
not difficult to build, so later I build another one on a scrap chassis.
Same sweet sound, surprising deep and clear bass, the OPT is not
that big. It looks like crap so I decided to rebuild it, on a new chassis.
This is the red one you see, just started today.
I use 2 U shape canals, that will shield the "AC part" in the back from
the signal part in the front.
I am using lundahl horn speakers, the 1 - 2 watt drive the horn speaker
without problem, my wife start to complain about half volume.
This amplifier is well worth trying out, you will not regret it.
Jogeir.
Attachments
Nice build!
I found this a very interesting thread re distortion characteristics on the black plate tubes as i use a Bottlehead S.E.X. as my headphone amp which is a single ended 6DN7. Interestingly my preference has always been for the Black Plate Sylvania 6DN7's for reasons i could never really explain.
I found this a very interesting thread re distortion characteristics on the black plate tubes as i use a Bottlehead S.E.X. as my headphone amp which is a single ended 6DN7. Interestingly my preference has always been for the Black Plate Sylvania 6DN7's for reasons i could never really explain.
6DN7 Horn
Finished is the most simple as can be, shaker box, a spray can 🙂
It turn out to be nice, four thin layers.
The speakers I made my self, a friend of mine how is a carpenter
made the front and the sides from Acacia wood. From own tree here
in the Pilippines. As the Ark of the Covenant 🙂
We have very nice wood here, the wood sides og the 6DN7 is Mahogany.
I will continue tomorrow, I am retired now, so I have time to build
amplifiers and other stuff.
Jogeir.
Finished is the most simple as can be, shaker box, a spray can 🙂
It turn out to be nice, four thin layers.
The speakers I made my self, a friend of mine how is a carpenter
made the front and the sides from Acacia wood. From own tree here
in the Pilippines. As the Ark of the Covenant 🙂
We have very nice wood here, the wood sides og the 6DN7 is Mahogany.
I will continue tomorrow, I am retired now, so I have time to build
amplifiers and other stuff.
Jogeir.
Attachments
Thank you all for the nice compliments.
If 7N7 don't mind, I will continue to update you with my 6DN7 build.
I have a tolerant wife that let me have big guns (speakers) like this in our living room.
tolerant
"Showing willingness to allow the existence of opinions or
behaviour that one does not necessarily agree with"
Jogeir
If 7N7 don't mind, I will continue to update you with my 6DN7 build.
I have a tolerant wife that let me have big guns (speakers) like this in our living room.
tolerant
"Showing willingness to allow the existence of opinions or
behaviour that one does not necessarily agree with"
Jogeir
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