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Old 14th February 2014, 08:34 AM   #11
Tesla88 is offline Tesla88  Italy
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Quote:
How about GU-29 in parallel? (Both sections in parallel)
I can try this

Quote:
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

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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
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Old 14th February 2014, 09:57 AM   #12
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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
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Old 14th February 2014, 02:51 PM   #13
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Originally Posted by ErikdeBest View Post
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. 100 ma current doesn't enough for two paralleled triods. Every triod sound good with current more 60-70 ma.
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Old 14th February 2014, 04:22 PM   #14
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Originally Posted by azazello View Post
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.
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Old 14th February 2014, 04:31 PM   #15
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The 6AS7 (or 6S19P) aren't known for their linearity, but if that is not a problem, I still think the 1k5 will work well. I am attaching the 6AS7 curves with operating point 100V/100mA and 1k5 load.
Attached Images
File Type: png 6AS7.png (84.2 KB, 167 views)
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Old 14th February 2014, 04:39 PM   #16
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3 x 4P1L in PSE (triode). Ua about 220V-240V, Ik 3 x 33mA = 100mA. Power 3 x 2.5W = 7.5W
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Old 14th February 2014, 06:25 PM   #17
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Originally Posted by needtubes View Post
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.

It's very hard to find 6 matched 4P1L....
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Old 14th February 2014, 11:09 PM   #18
rmyauck is offline rmyauck  Canada
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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/Tra..._Tube_Amp.html

Last edited by rmyauck; 14th February 2014 at 11:13 PM.
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Old 22nd March 2014, 07:11 PM   #19
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Old 22nd March 2014, 07:37 PM   #20
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