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 NEW  Matt presents bias and operation data for the 6V6 tube in SE operation - 6V6 Single-Ended (SE) Ultra Linear (UL) Bias Optimization.

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PostPosted: 30 Nov 2011, 19:44 
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Oops! :blush: B+ on the power stage is ~220v not 200v.
Attachment:
B+.png
Sorry about that.


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PostPosted: 30 Nov 2011, 20:42 
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Location: Montreal, Canada
Suncalc wrote:
Oops! :blush: B+ on the power stage is ~220v not 200v.
Attachment:
B+.png
Sorry about that.


Hi Matt, Geek

Thanks a lot for the help !!

Regarding the 6W6, I read in many places on the web that this unappreciated tube sounds excellent when triode strapped within of course its power rating. Personally I never heard but I will soon find out.

Now I have an idea on how to choose an appropriate operating point :thumbsup: that -45V did not make any sense.

My OPT are 3K but I would have to check when I go back home, I'm presently in training in Richmond, Vancouver, Canada.

I noted all your precious feedback but I will keep using the 6P1N-EV since I do not have any 12AU7 and I just ordered another bunch of 6N1P-EV from e-bay.

I already have 2 more small power amp which are; 1. triode strapped 12AV5GA (love the sound) and the Chinook 2W SET. Both amps play very well, looking forward to compare them to the 6W6.

I have attached the modified schematics, I need to add an additionnal resistor + cap to lower the voltage drop from 315 to 210Vdc..without it the small IFR840 will have to dissipate about 10W :hot:

My PT is slightly too big, kinda wonder if I can use it for a triode strapped 6W6 PP ?

Thanks,
Isophon

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DIY Tube Amp : RH84 SE | 6V6 SET | 13FD7 SET (Chinook) | 807 UL SE | 6BQ5 Class A PP UL | 6LR8 SE
DIY Spkrs : Cyburgs Needle | MLTL (FE206E) | CSS EL70 BR | Open Baffle (Alpha 15A + FE206En) (in process...)
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PostPosted: 30 Nov 2011, 20:56 
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Isophon wrote:
I'm presently in training in Richmond, Vancouver, Canada.


I'm 1.25 hours east of you up the Valley in east Chilliwack 8-)

(psssst, don't call Richmond "Vancouver" to a Richmondite.... y'all might get a knuckle sandwhich :shock: )

Cheers!

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PostPosted: 30 Nov 2011, 22:18 
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Isophon wrote:
I noted all your precious feedback but I will keep using the 6P1N-EV since I do not have any 12AU7 and I just ordered another bunch of 6N1P-EV from e-bay.
Just make sure that you get the -EV versions. They are a significantly different tube from the non-EV versions.

I would also dump the screen resistor. For this tube it is not required for class A operation.

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PostPosted: 30 Nov 2011, 23:38 
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Location: Montreal, Canada
Suncalc wrote:
Isophon wrote:
I noted all your precious feedback but I will keep using the 6P1N-EV since I do not have any 12AU7 and I just ordered another bunch of 6N1P-EV from e-bay.
Just make sure that you get the -EV versions. They are a significantly different tube from the non-EV versions.

I would also dump the screen resistor. For this tube it is not required for class A operation.


Thanks for the help.

I have removed the screen resistor.

I presently have 10 x 6N1P and 10 x 6N1P-EV, besides the nice corrosion free contact on the EV type, are there any difference in electrical params ?

Thanks,
Isophon

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PostPosted: 01 Dec 2011, 11:35 
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Location: Northern VA
The main difference between the 6n1p and the 6n1p-eb (ev) is that the EV version is more rugged so it's less susceptible to microphonics and it lasts much longer, almost twice as long as the standard. I believe the EV is specified for military use as well.

I used the 6W6 for about a month and really enjoyed it's sound. I even tried it in Ultra Linear mode and it worked fine. I can't recommend using UL however, since I didn't use it long term that way. I ran mine at 225V and 45 mA with fixed bias with a 2K5 load.


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PostPosted: 02 Dec 2011, 00:04 
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rock4016 wrote:
The main difference between the 6n1p and the 6n1p-eb (ev) is that the EV version is more rugged so it's less susceptible to microphonics and it lasts much longer, almost twice as long as the standard. I believe the EV is specified for military use as well.

I used the 6W6 for about a month and really enjoyed it's sound. I even tried it in Ultra Linear mode and it worked fine. I can't recommend using UL however, since I didn't use it long term that way. I ran mine at 225V and 45 mA with fixed bias with a 2K5 load.


Thanks to all :mrgreen:

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DIY SS Amp : LM3875 GC | TA2024 | TA2020 (AMP-6) | TA2022 | Amp Camp Amp | JLH
DIY Tube Amp : RH84 SE | 6V6 SET | 13FD7 SET (Chinook) | 807 UL SE | 6BQ5 Class A PP UL | 6LR8 SE
DIY Spkrs : Cyburgs Needle | MLTL (FE206E) | CSS EL70 BR | Open Baffle (Alpha 15A + FE206En) (in process...)
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PostPosted: 11 Jun 2013, 20:03 
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Hi guys,

I finally built the small amp. I did not put any form of global feedback since this is a triode strapped output tube, triode by them self already have some local feedback.

Well it's sounds very good but there is basically no bass control, it's very floppy. The amp is driving a pair of Fostex FE206E in a MLTL enclosure.

I did some more research following these some how disappointing results (with 5-6 db of global feedback the bass is more firm but not that much)

I noticed the following Plate Resistance of the 6W6 is quite high at 1600 ohm, that could explain the poor lack of bass control. For comparison the 6FD7 (Chinook amp designed by Geek) is 800 ohm, the 2A3 also 800 ohm, the popular 6EM7 is 750 ohm. To my surprise the 6DN7 (sex amp) is 2000 ohm. People say that this triode strapped 6W6GT tube sounds like a 45 triode, well I have never heard a 45 but guess what...the Plate resistance is also 1600 ohm, just like the 6W6...could that explain the similarities ???

I think I will keep the chassis and the VA section and switch the amp back to a 6AV5 which sounds like a small 300B.

BR,
Iso

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DIY Spkrs : Cyburgs Needle | MLTL (FE206E) | CSS EL70 BR | Open Baffle (Alpha 15A + FE206En) (in process...)
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PostPosted: 15 Jun 2013, 22:30 
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Location: Arizona, USA
Hi, The design should work, I probably would use a 12AT7 without a cathode bypass capacitor and wrap a negative feed back loop around it from the output to clean up the distortion a bit. Anything over about 2% is more than I care for. I would suspect that it would behave a lot like a 6AQ5 so circuits designed around that tube should work. Those designed for 6V6 if you de-rate the power a bit to match the dissipation ratings should work as well.


Good listening
Bruce

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PostPosted: 18 Jun 2013, 00:05 
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Thanks Bruce but I already converted the amp back as a 6AV5GA SET. These tubes triode strapped are quite something, insanely linear and the funny part is the tube is rated 11W but my set-up is pushing through 21W in each and no red plate even when the room in pitch black. This tube is often compared to a small 300B but at least it has great bass compare to most std DHT.

The 6AV5GA idea comes from http://www.tubelab.com, cool site.

p.s. what a cool and rewarding hobby, I wanted to know how the 6W6 sounded, now I know ;-)

Since I had a 8 pin socket I also tried a 6V6 which I really liked despite the use of a 3K OPT.

Rgds,
Iso

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DIY SS Amp : LM3875 GC | TA2024 | TA2020 (AMP-6) | TA2022 | Amp Camp Amp | JLH
DIY Tube Amp : RH84 SE | 6V6 SET | 13FD7 SET (Chinook) | 807 UL SE | 6BQ5 Class A PP UL | 6LR8 SE
DIY Spkrs : Cyburgs Needle | MLTL (FE206E) | CSS EL70 BR | Open Baffle (Alpha 15A + FE206En) (in process...)
DIY Pre-Amp : MooseFET.
To come : MLTL (CSS enabled EL70) + more tube amp...


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