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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: 23 Dec 2017, 19:30 
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Joined: 06 Jun 2008, 18:23
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Location: Australia
I put the 6080 in and its quite microphonic. I put the Svet. back in and there is barely a sound when tapped quite strongly.

I'm not saying all RCAs are microphonic but the ones I have and now the 6080 are very microphonic. I have two Svets, bought together and a few spare E88CCs (6V) so well covered.

It is my intension to sell this HP amp because I have plans for a more extensive one. That will be my forth based on this design.

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Projects: "Sanctum" - 12AU7 and 6AS7 direct coupled headphone amp | "retro-Oatley 6J6" - 6J6 push-pull headphone amp with OPTs | "retro-Hiraga" - Jean Hiraga Le Monster
Website: retro-thermionic


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PostPosted: 28 Dec 2017, 06:27 
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I have been blaming my new HP amp for an extremely quiet hum. It appears the noise may be coming from my Pi music server and HDMI 24/192 audio stripper.

I have to investigate more.

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Projects: "Sanctum" - 12AU7 and 6AS7 direct coupled headphone amp | "retro-Oatley 6J6" - 6J6 push-pull headphone amp with OPTs | "retro-Hiraga" - Jean Hiraga Le Monster
Website: retro-thermionic


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PostPosted: 28 Dec 2017, 06:31 
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The HP amp now has a stained isolation plinth.
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Projects: "Sanctum" - 12AU7 and 6AS7 direct coupled headphone amp | "retro-Oatley 6J6" - 6J6 push-pull headphone amp with OPTs | "retro-Hiraga" - Jean Hiraga Le Monster
Website: retro-thermionic


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PostPosted: 29 Dec 2017, 01:58 
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Joined: 08 Aug 2009, 03:11
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Location: Chilliwack, BC
Just keeps getting better! :D

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* Ratings are for transistors - tubes have guidelines*
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PostPosted: 29 Dec 2017, 03:13 
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Geek, thanks mate.

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Projects: "Sanctum" - 12AU7 and 6AS7 direct coupled headphone amp | "retro-Oatley 6J6" - 6J6 push-pull headphone amp with OPTs | "retro-Hiraga" - Jean Hiraga Le Monster
Website: retro-thermionic


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PostPosted: 30 Dec 2017, 19:03 
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As much as I loved the sound of the Gold Lion, being a high gain tube, with some more sensory phones, it was bringing up a slight hum. This was annoying as my fav. phones are my Sennheiser 700s. They are a high sensitivity phone. I couldn't use them with the Gold Lions.

So I bit the bullet and rewired the amp for 12V filaments in parallel (6V) and tested the well used12AU7s I have. One Miniwatt tube came up 85% on emissions weaning it is well in its good zone. Dropping this in gives me a dead quiet amp at any vol. even with the 700s. Different sound but not nessecarily bad. But at least I can use my lovely 700s.

I had a tested 12AT7 which I tried. Strange, no hum but I could hear the pot when it turned it??? Never heard that before. I'm staying with the 12AU7. I may order some Psvane "T" series MKII 12AU7s. I have been very impressed with thier top of the range 12A** series lately.

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Projects: "Sanctum" - 12AU7 and 6AS7 direct coupled headphone amp | "retro-Oatley 6J6" - 6J6 push-pull headphone amp with OPTs | "retro-Hiraga" - Jean Hiraga Le Monster
Website: retro-thermionic


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