JLH said:
Hi to all diyaudio friends . I am finishing two monoblocks of this
http://members.at.infoseek.co.jp/lagarto/shishido/images7/805SE.png . I changed the WE437 to the 6C45 as it is spoken as direct sub . I have heard good and bad reviews about this russian valve but now I have some doubts . What other vales can i use in this schema from you diyaudio friends point of view?
http://www.4shared.com/file/77018805/1835118a/P9090055.html
rdf said:
I had an hour of listening with an unboxed Kef old speaker and i know already that yes it works and seemed to sound correctly , just a hum problem that stops when i pull out the 6C45 and i will try to fix as soon as i finish the other monoblock .
And i can say that i ravished when i saw that the 820 volts are down to near 300v just 20 or 30 seconds of power off , good for safety. It was my biggest fear of making this amp .
Hi inertial
FWIW, the tube data sheet shows that the microphonic noise is 150 mV or less with Ra = 2 kOhm. This is OK but not in the same range as the tubes with lowest microphonics.
http://www.tubes.ru/techinfo/AmateurRadio/6c45p-e.html
Karsten
FWIW, the tube data sheet shows that the microphonic noise is 150 mV or less with Ra = 2 kOhm. This is OK but not in the same range as the tubes with lowest microphonics.
http://www.tubes.ru/techinfo/AmateurRadio/6c45p-e.html
Karsten
Hi Karsten,
Thanks, good to know. But, perdone me, I am more pragmatic and usually do not look at these datas.
I symply tap the bulb and hear with my ear near to the speaker if it
produce " klang-klang" or not !
Very scientific, eh!?
Anyway this "stupid" test is IMO very important ; zero noise is my target , as my belowed Sowtek 6922, and I pretend the same for the
others valves
I know, it is very rare quality, maybe unrealistic but I am firm on my point .
Cheers,
Paolo
Thanks, good to know. But, perdone me, I am more pragmatic and usually do not look at these datas.
I symply tap the bulb and hear with my ear near to the speaker if it
produce " klang-klang" or not !
Very scientific, eh!?Anyway this "stupid" test is IMO very important ; zero noise is my target , as my belowed Sowtek 6922, and I pretend the same for the
others valves
I know, it is very rare quality, maybe unrealistic but I am firm on my point .
Cheers,
Paolo
Oh thanks Tugatweaker,
This confirm my suspect
Good to know!
IMO people "underavalutate" microphonicity. When system is sounding,
amplifiers are "immersion" in a very bad complex vibrational field; vibrations
come from speakers via the floor first and from air second. It is not a
microscopic effect, it is macro! ( put your hand on the cover of your amp).
I have made extensive experimentations on this field during the years
and I have learned to not undervalutate this phenomena.
Just my 2c.
P.S.: Very Nice amps!
Cheers,
Paolo
This confirm my suspect
Good to know!IMO people "underavalutate" microphonicity. When system is sounding,
amplifiers are "immersion" in a very bad complex vibrational field; vibrations
come from speakers via the floor first and from air second. It is not a
microscopic effect, it is macro! ( put your hand on the cover of your amp).
I have made extensive experimentations on this field during the years
and I have learned to not undervalutate this phenomena.
Just my 2c.
P.S.: Very Nice amps!
Cheers,
Paolo
All valves are microphonic one more than other, we must do the right things to fit them well . You mencioned 6922 , where are you using it ? Preamp ? Do you really notice a big sonic diference when you listen to it ? Is it the brand ? Is it the valve 6DJ8/ECC88/ECC808/6922 ? If it is the valve type i know some ECC808 Telefunken from a Sonic Frontiers SFD2 dac and i don't
hear nothing special with the microphonics absence .
PS. Of course hiting the valve or near it in search for microphonics is radical , too much , not musical .
hear nothing special with the microphonics absence .
PS. Of course hiting the valve or near it in search for microphonics is radical , too much , not musical .
it is Sowtek 6922. Brand of course is important. Some Tesla ECC88 was microphonics, philips also, a mullard not at all and so on.
Yes, I can hear a clear difference from those tried and the less microphonic, the better. Why are you wondered?
The fact a phenomena is not eliminable because it is intrinsic to the nature of the device ( tube) do not mean it is irrilevant.
And the microphonic effect is , from all the point of view, a negative caractheristic.
My tube is in the driver stage before the power follower!
Cheers,
Paolo
Yes, I can hear a clear difference from those tried and the less microphonic, the better. Why are you wondered?
The fact a phenomena is not eliminable because it is intrinsic to the nature of the device ( tube) do not mean it is irrilevant.
And the microphonic effect is , from all the point of view, a negative caractheristic.
My tube is in the driver stage before the power follower!
Cheers,
Paolo
I have had good luck with the Sovtek 6H30PI biased at 12 to 15 mA with a plate cathode voltage of 85 to 90 volts. This circuit I attached I run with a regulated 170 volt supply. It is the lowest noise tube preamp I have ever encountered and the tubes I have are not microphonic. I can't see any change on the scope trace when I tap the tube glass, even if I tap it sharply. I noticed a faint hum with AC on the filaments, so I have swithced them to DC. I only have three of the 6H30PI's so I did not have a big sample to evaluate for microphonics.
I have tried the 6H30PI at several different operating points in other circuits. I have also had good luck at 60 volts and 20 mA. I have found it to be a very linear and good sounding tube but like all tubes it must be biased properly for best results. From my testing over the years if you want to run at lower currents, the 6SN7 is probably a better choice over a 6H30PI.
I have tried the 6H30PI at several different operating points in other circuits. I have also had good luck at 60 volts and 20 mA. I have found it to be a very linear and good sounding tube but like all tubes it must be biased properly for best results. From my testing over the years if you want to run at lower currents, the 6SN7 is probably a better choice over a 6H30PI.
Attachments
Thanks Tom, very appreciated input datas !
Seems to me that there is a big "variance" about these 6H30PI,
, ie opposite comments here,so a big factor can be the luck in find
a good one or make a brutal selection. I assume there is not strange
"marks" or letters in these russian tubes, no way to choice before,
just luck
Cheers,
Paolo
Seems to me that there is a big "variance" about these 6H30PI,
, ie opposite comments here,so a big factor can be the luck in find
a good one or make a brutal selection. I assume there is not strange
"marks" or letters in these russian tubes, no way to choice before,
just luck
Cheers,
Paolo
My experience with 6C45 is that one can go about 20% overvoltage IF you make sure that you correspondingly lower the current the tube is running at. Max rating is 40mA...if going overvolts, I would drop max current to 20 or 25mA.. Be carful of total watts of dissapation. Please note also that most often, tubes will sound better, at higher current, so I suggest changing the plate load to drop the quesecent plate voltage down, so you can safely bias the current higher, rather than lower.
Audiowolf
Audiowolf
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