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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: 06 Aug 2013, 00:52 
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Location: Australia
Geek wrote:
If you so wish :D

Not all amps have to be built the same way and the client is happy:
http://www.glowinthedarkaudio.com/se12by7a.html

There is a 100 ways to skin a cat. Getting satisfaction and joy from the hobbies is why we do it. Hey I like the dark timber, what is it?

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Projects: "Sanctum" - 12AU7 and 6AS7 direct coupled headphone amp | "retro-Oatley 6J6" - 6J6 push-pull headphone amp with OPTs | "Mimic Carbon" - carbon resistors and PIO caps. MM phono preamp
Website: retro-thermionic


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PostPosted: 06 Aug 2013, 01:00 
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Isophon wrote:
mwhouston wrote:
For a number of tube amps I have built lately instead of having the driver tube upfront I'm setting it back into the amp and placing the RCA just behind it. I don't use shielded cable in my amps but using this method means the wires from RCA to grid are only a few inches long. I use heavily twisted wire warp wire to connect RCA to grid. Haven't had a problem yet.

The idea of having the driver tube upfront of a power amp seems wrong to me. By having the driver tube at the back of the amp (when RCA are mounted rear-ward, more often than not) it would make sense to have the driver tube back there. Wires from RCA to driver are therefore shortest. In most cases the driver tube is some small unexciting 6N1P or 12AX7. Even a 50 year treasure (black glass and all) with ceramic base as I have used a few of lately can take back row to say a Shuguang 300B-Z.

With driver tube upfront and RCAs on the back you will you have the worst situation for long wires, shielded or not.



Hi Mark,

I never have hum problem with RCA in the back and driver in the front, please check your layout.

The 6N1P-EV is an excellent driver when bias properly (9-10mA), Vp 200V it sings :D

Rgds,
Iso

The last two EL34 amps I built and sold both myself and new owners love. I think a lt has to do with the 6N1P. It's a gutsy little tube.

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Projects: "Sanctum" - 12AU7 and 6AS7 direct coupled headphone amp | "retro-Oatley 6J6" - 6J6 push-pull headphone amp with OPTs | "Mimic Carbon" - carbon resistors and PIO caps. MM phono preamp
Website: retro-thermionic


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PostPosted: 06 Aug 2013, 12:26 
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Location: Chilliwack, BC
mwhouston wrote:
Hey I like the dark timber, what is it?


That is a rarity ... a teak species (forget the fancy name for it) that became endangered after I bought it :blush:

I can see why it was likely harvested to near extinction - it takes oil beautifully and with a simple 220 grit sand paper after that, I sprayed a pearl-texture laquer that gripped like crazy onto it (can't peel it off with a thumbnail).

Cheers!

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PostPosted: 06 Aug 2013, 17:45 
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Geek: a nice piece of timber can really set off an amp particularly a tube amp. It just gives the build that retro feel.

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Projects: "Sanctum" - 12AU7 and 6AS7 direct coupled headphone amp | "retro-Oatley 6J6" - 6J6 push-pull headphone amp with OPTs | "Mimic Carbon" - carbon resistors and PIO caps. MM phono preamp
Website: retro-thermionic


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PostPosted: 03 Sep 2016, 15:22 
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Joined: 03 Sep 2016, 15:19
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Hello guys,
I'm very interested in building this amp... has anyone build this recently?

Many thanks,
Rich


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PostPosted: 28 Feb 2017, 23:10 
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Hi. I have a large stash of 12BY7As and hope to embark on a build of this amp. Does a two tube per channel parallel version make sense? I have at least 150 of these tubes, but no 8K-8 Ohm OPTs. I do have several matched pairs of 5K-8 Ohm OPTs. I was thinking that these would better suit a pair of 12BY7As per side. Am I okay with the 5K-8 Ohm OPTs, or would a parallel set up be better. Thanks for any advice or recommendations.


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PostPosted: 01 Mar 2017, 02:57 
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How about an image of the tube.

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Projects: "Sanctum" - 12AU7 and 6AS7 direct coupled headphone amp | "retro-Oatley 6J6" - 6J6 push-pull headphone amp with OPTs | "Mimic Carbon" - carbon resistors and PIO caps. MM phono preamp
Website: retro-thermionic


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PostPosted: 01 Mar 2017, 03:55 
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Hi,

When paralelling tubes, current draw is doubled (screen and anode), so adjust PSU, cathode and screen accordingly. Anode load is also halved, so 4K-5K:8R is just fine.

Cheers!

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* Ratings are for transistors - tubes have guidelines*
Home: GeeK ZonE
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PostPosted: 01 Mar 2017, 05:10 
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Thanks Gregg. I wonder if paralleling will hurt it's SQ. I've never done it before. I played around with the pentode curves to see what a 5K load OPT looks like and it doesn't look great. Would a anyone happen to have triode curves for this tube? Or recommended parameters for triode connection? Parallel triode connected 12BY7a might be good too, no? MWHouston: With respect to pictures, did you want to see a picture of the bag of tubes, or some of the tubes in particular? Most are 12BY7a, but there are also some 12BV7 and some 12DQ7. I am happy to oblige.


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PostPosted: 01 Mar 2017, 05:59 
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Just some images of the 12BY7. Thanks.

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Projects: "Sanctum" - 12AU7 and 6AS7 direct coupled headphone amp | "retro-Oatley 6J6" - 6J6 push-pull headphone amp with OPTs | "Mimic Carbon" - carbon resistors and PIO caps. MM phono preamp
Website: retro-thermionic


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