Hi guys, i'm working on a low cost amplifier using a putput transformer with 1k or 1.5k primary 100mA rated and i'm wondering what tube for the output stage and B+ value ?
The goal is 8W but 5W is enough...i would avoid GNFB
What about using EL34 triode connected ?
EL86 maybe ? i've seen this tube driving low load at low B+ without problems
6080 can drive 1K easily but need a lot of drive voltage at grid.
thank you all
The goal is 8W but 5W is enough...i would avoid GNFB
What about using EL34 triode connected ?
EL86 maybe ? i've seen this tube driving low load at low B+ without problems
6080 can drive 1K easily but need a lot of drive voltage at grid.
thank you all
Thank you, i've triedFor EL34 triode connected you need 3k or 5k OPT
Isn't a bit overkill ? and expensive at least heremaybe 6c33c
Cathode feedback, intresting i can give it a try having a bunch of them...maybe screen drive?PL 504 with cathode feedback
About 2A3 and F2a , i don't have any ...
I have some 6P13S , 6P31S , EL36 , GU32 (832) , GU29 (829)
Thanks
I can try thisHow about GU-29 in parallel? (Both sections in parallel)
it is curve exploited for PL 504
so good for approximalty 200 or 250 V= , OPT = 3.0 K , power out at 8 ohms = 7 W ~
Yes but my OPT is 1 - 1.5K
Very suitable and cheep decision is 6S19P /Russian/ in parallel
man i've never seen this tube before...amazing, i like it so much
I'm just a bit worried about shipping most ebayers who sell this tube are from russia and they can't guarantee for deadline to italy.
Anyway i found this seller :
6S19P Russian MATCHED QUAD VERY STRONG TUBES !!!!! | eBay
Do you think is ok ? Anyone with experience in buying tubes from russia to italy?
Thanks
Hi Tesla88
Maybe the 6CB5?
It is said that the 6S19P is like half a 6AS7, with a mu of ~2. It is also said that these tubes work best with low voltage/high current (like 100V at 100mA for 6AS7). In this case it will require about -30V bias, or 130V on the plate and 300R cathode resistor. Generating a signal of 60V PP (about 22VRMS) to drive this is not very hard and can be done with a single stage. As the mu of neither 6AS7 ot 6S19P is very high, miller capacitance will be low, which is good.
What you can also consider is the accordion amp by Broskie Here is a thread with an example. This is something I want to try out myself one day.
as always, a thousand possibilities
Maybe the 6CB5?
It is said that the 6S19P is like half a 6AS7, with a mu of ~2. It is also said that these tubes work best with low voltage/high current (like 100V at 100mA for 6AS7). In this case it will require about -30V bias, or 130V on the plate and 300R cathode resistor. Generating a signal of 60V PP (about 22VRMS) to drive this is not very hard and can be done with a single stage. As the mu of neither 6AS7 ot 6S19P is very high, miller capacitance will be low, which is good.
What you can also consider is the accordion amp by Broskie Here is a thread with an example. This is something I want to try out myself one day.
as always, a thousand possibilities
But 1 - 1.5 kohm are small for one triod of 6AS7. 100 ma current doesn't enough for two paralleled triods. Every triod sound good with current more 60-70 ma.Hi Tesla88
Maybe the 6CB5?
It is said that the 6S19P is like half a 6AS7, with a mu of ~2. It is also said that these tubes work best with low voltage/high current (like 100V at 100mA for 6AS7). In this case it will require about -30V bias, or 130V on the plate and 300R cathode resistor. Generating a signal of 60V PP (about 22VRMS) to drive this is not very hard and can be done with a single stage. As the mu of neither 6AS7 ot 6S19P is very high, miller capacitance will be low, which is good.
What you can also consider is the accordion amp by Broskie Here is a thread with an example. This is something I want to try out myself one day.
as always, a thousand possibilities
But 1 - 1.5 kohm are small for one triod of 6AS7.
The Lilliput amp uses one half of a 6AS7 per channel into a ~1.5k load.
But if transformer is 1 kohm, one triode of 6AS7 is not for using, but two - need 120-140ma,.... suitable are two 6S19P with 2 x 50 ma.The Lilliput amp uses one half of a 6AS7 per channel into a ~1.5k load.
It's very hard to find 6 matched 4P1L....
This uses 1.5-1.6K so close and also uses affordable in production tubes. Only 3W/CH , but he says it works like a bigger amp.
http://www.transcendentsound.com/Transcendent/Transcendent_Sound_Cathode_Follower_Tube_Amp.html
http://www.transcendentsound.com/Transcendent/Transcendent_Sound_Cathode_Follower_Tube_Amp.html
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