SE design using 10k OPTs

roundel325 · 19th May 2004, 04:05 PM

I've got a pair of 10K OPTs with 4 and 8 ohm secondaries. I also have a pair of 6l6GCs, with a mess of preamp tubes around. My question is, how can I put these OPTs to use? I think maybe I can run the 6l6s in triode w/ like 350 B+ and get a few watts while staying under their 30w dissapation. Data sheet says in pentode mode I should expect 10-15% distortion with a 4k load. That seems like alot. Will a greater load increase or decrease distortion. Maybe some NFB, but how much? Good idea?

It seems like most designs call for a 5k load or less. Is their some other tube that is happy driving a 10k load? I think maybe I should just build it and find out... What do y'all think?

Wow, this post has an abundance of question marks dosen't it...

-Jared

Bryan · 19th May 2004, 04:18 PM

Hey Jared,

IIRC, a pair of 10K OPT's would work nicely with the 845

rafalc · 19th May 2004, 04:40 PM

Would go great with VT-25 or 801 but very low power around 1W

Sch3mat1c · 19th May 2004, 06:23 PM

One 12AU7 with both sections in parallel?

Problem is you'll need a really, really high voltage to get any power output. No matter what you do.

Tim

elctrifrier · 15th June 2004, 09:23 PM

10K to 4 and 8 ohms - ok, that is 50 and 35 to 1 turns ratio, which could be translated as 5K to 4 and 2 ohms, but you need to know how many watts they can handle - how big are they?

Eli Duttman · 16th June 2004, 03:47 AM

Consider taking a page out of the DECWARE SE84's book. Triode strapping the 6L6s with 100 Ohm resistors will be FINE. You will end up with about 5 BALLSY W. Distortion will be LOW and the damping factor will be HIGH for a SET amp.

A pair of true mid 90s efficient 4 Ohm speakers connected to the 8 Ohm taps might give you a pleasant surprise. 2 Ohm Parker 95s/98s connected to the 4 Ohm taps could be excellent.

planet10 · 16th June 2004, 05:30 AM

How big are the OPTs?

10K is often used with EL84, EL95, ECL82, ECL86, ECC80.

It would have to be a substantial OPT for 845s.

dave

dhaen · 16th June 2004, 06:52 AM

You need to establish how much standing current (DC) they can take.

IMO pentodes need fedback to sound reasonable. Triodes are best without.

19th May 2004, 04:05 PM	#1
roundel325 diyAudio Member Join Date: Mar 2004 Location: Ohio	SE design using 10k OPTs I've got a pair of 10K OPTs with 4 and 8 ohm secondaries. I also have a pair of 6l6GCs, with a mess of preamp tubes around. My question is, how can I put these OPTs to use? I think maybe I can run the 6l6s in triode w/ like 350 B+ and get a few watts while staying under their 30w dissapation. Data sheet says in pentode mode I should expect 10-15% distortion with a 4k load. That seems like alot. Will a greater load increase or decrease distortion. Maybe some NFB, but how much? Good idea? It seems like most designs call for a 5k load or less. Is their some other tube that is happy driving a 10k load? I think maybe I should just build it and find out... What do y'all think? Wow, this post has an abundance of question marks dosen't it... -Jared

19th May 2004, 04:18 PM	#2
Bryan diyAudio Member Join Date: Jun 2003 Location: Reading MA	Hey Jared, IIRC, a pair of 10K OPT's would work nicely with the 845 __________________ Dont take life too seriously, you will never get out alive!

19th May 2004, 06:23 PM	#4
Sch3mat1c diyAudio Member Join Date: Jan 2003 Location: Milwaukee, WI	One 12AU7 with both sections in parallel? Problem is you'll need a really, really high voltage to get any power output. No matter what you do. Tim __________________ Seven Transistor Labs Projects and Resources

16th June 2004, 03:47 AM	#6
Eli Duttman diyAudio Member Join Date: Apr 2004 Location: Plainsboro, NJ	Consider taking a page out of the DECWARE SE84's book. Triode strapping the 6L6s with 100 Ohm resistors will be FINE. You will end up with about 5 BALLSY W. Distortion will be LOW and the damping factor will be HIGH for a SET amp. A pair of true mid 90s efficient 4 Ohm speakers connected to the 8 Ohm taps might give you a pleasant surprise. 2 Ohm Parker 95s/98s connected to the 4 Ohm taps could be excellent. __________________ Eli D.

16th June 2004, 05:30 AM	#7
planet10 frugal-phile(tm) diyAudio Moderator Join Date: Oct 2001 Location: Victoria, BC, NA, Sol III Blog Entries: 5	How big are the OPTs? 10K is often used with EL84, EL95, ECL82, ECL86, ECC80. It would have to be a substantial OPT for 845s. dave __________________ community sites t-linespeakers.org, frugal-horn.com, frugal-phile.com ........ commercial site planet10-HiFi p10-hifi forum here at diyA


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19th May 2004, 04:40 PM	#3
rafalc diyAudio Member Join Date: Sep 2003 Location: Hong Kong	Would go great with VT-25 or 801 but very low power around 1W

15th June 2004, 09:23 PM	#5
elctrifrier diyAudio Member Join Date: Jun 2004 Location: Gonderange, Luxembourg	10K to 4 and 8 ohms - ok, that is 50 and 35 to 1 turns ratio, which could be translated as 5K to 4 and 2 ohms, but you need to know how many watts they can handle - how big are they?

16th June 2004, 06:52 AM	#8
dhaen diyAudio Moderator Emeritus Join Date: Jun 2002 Location: U.K.	You need to establish how much standing current (DC) they can take. IMO pentodes need fedback to sound reasonable. Triodes are best without.

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