• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Octal equivalents for 6C45?

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Jump to Latest
EC8010

EC8010

Ex-Moderator
Joined 2003
No. 6C45 is arguably the finest and latest expression of small signal triode technology. WE437A or their UK subsidiary STC's 3A/157M are better but they are both made of unobtanium. The WE416 contains both unobtanium and berylium, making it simultaneously expensive and poisonous.
 
jlsem

jlsem

Member
Joined 2003
rdf

rdf

Member
Joined 2004
The 6c4P or 6c45P? The first is a "double-anode kenotron". If the latter, how are you using them? My experience so far is 'best' depends on application. After lots of futzing around I finally settled on Kuei Yang Wang's bias current (though I doubt bias method) recommendations. As a driver for an EL84 SE (sledge meets fly), a red LED - about 1.75 Vdc - on the cathode bypassed with a 0.1 poly/film and a IXYS CCS for a plate load at ~10 ma. From memory second harmonic was around ~60 dB down, third about 30 dB lower and most everything else below -10 dB, noise below the limit of my measurments. Raising anode current lowers the 2nd but quickly starts pulling higher harmonics above the noise floor. Might account for the reputation for sounding 'steely' or 'solid state' you read sometimes.

Used with a 5k:8 James SE OPT as a headphone amp the sweet spot for me right now is around 175-165 Vdc on the plate and 20 ma anode current, also LED biased. Same deal re: harmonics. At very loud levels using low impedance, average efficiency headphones THD and IMD are below 0.2 %, HD by far 2nd harmonic and no harmonic above the 5th closer than -100 dB to the fundamental.
 
jlsem

jlsem

Member
Joined 2003
The 6c4P or 6c45P? The first is a "double-anode kenotron".
Click to expand...

Check my earlier post: the 6C4-EB (6S4-EV) is a small triode similar to the WE417A but with slightly more gain and correspondingly lower transconductance. I would bias it with a battery and load it with a choke or interstage transformer as these types of tubes demand.

John
 
Ryssen

Ryssen

Member
Joined 2003
It is the 6c4P-EB,I am going to use them as a driver for an 6B4G SE amp.Not direct coupled,I have 320v it says in the datasheets max volt for the tube is 150v is it so?Do I need 15ma to drive the 6B4G or is it just that 6c4P-EB sounds best at 15ma?I want to use resistors at the anode and the cathode,I´ve read sommewhere that LED´s does funny things to the sound?:xeye: :D :cool:
 
rdf

rdf

Member
Joined 2004
jlsem said:


Check my earlier post: the 6C4-EB (6S4-EV) is a small triode similar to the WE417A but with slightly more gain and correspondingly lower transconductance. I would bias it with a battery and load it with a choke or interstage transformer as these types of tubes demand.

John
Click to expand...

Hmmm, that certainly matches the description on E-bay, though they list it as 6C4'P'. I went by the entries in ETS:

http://www.mif.pg.gda.pl/homepages/frank/sheets/113/6/6C4P.pdf
http://www.mif.pg.gda.pl/homepages/frank/sheets/112/6/6C4PEV.pdf

Questionable conversion from the Cyrillic?
 
rdf

rdf

Member
Joined 2004
ryssen said:
It is the 6c4P-EB
Click to expand...

My mistake, I took 6c4p - without the '5' - to be a typo since the thread stared with 6c45p. That was the gist though, those are my favourite operating currents under two different uses for the latter. Both were chosen to minimize the generation of higher harmonics and my ear's been extremely pleased in both cases.


I´ve read sommewhere that LED´s does funny things to the sound?:xeye: :D :cool:
Click to expand...


:) Now you're in personal choice territory. I'm gobsmacked by the sound I'm getting into the EL84. I have compared and prefered it to RC and grid-leak biasing, but haven't tried battery. Not sure how LED biasing will work in your application since I'm guessing you'll need them in series to get sufficient grid voltage to allow the plate swing required.
 
SY

SY

Ex-Moderator
Joined 2002
SYclotron.com
The key to LED biasing without sonic "funnies" is current. If you get the current up past 10mA or so for most LEDs, the dynamic impedance becomes lower and more constant. One cool trick for using them with low current tubes like 6SL7 is to run a current source from the supply rail to the junction of the LED and the cathode to make up the difference. That does not inject supply noise, a common worry- the output impedance of the CCS and the dynamic impedance of the LED form a voltage divider which knocks down any supply noise by a whole lot of dB.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Top Bottom