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 NEW  Bruce Heran outlines the details and construction of his simple DIY 6DJ8 (ECC88) Tube Hi-Fi Headphone Amplifier Project.

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It is currently 20 Apr 2014, 05:47

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PostPosted: 07 Apr 2014, 20:12 
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Joined: 06 Jun 2008, 18:23
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Location: Australia
The single stage tube preamp is a very simple and good performing preamp but it will not drive heavy loads. It likes to see impedances of 250K or there abouts.To drive a tube amp I built with a interstage tranni front end I added a Pass BoZ single stage jFET preamp to the tube preamp. A BoZ will work into 400ohms and can provide large voltage swings.

A friend bought that preamp and wants another. This time I'm gong to add a Pass B1 jFET buffer to the back end of a 4S tube preamps. Look on this forum for threads about the two. The 4S I'm building is the MKIII which Suncalc designed and I re-named "The Black". I'm building all parts as separate modules; PS, B1 buffer, tube preamp, PS for the buffer etc. I have a dark wooden box with a lid in which all modules will be mounted the wired together.

So far I have the tube PS (250V) and the buffer complete. A 250K alps blue velvet will sit between the tube preamp and buffer. I have built a B1 some years back and this was followed by a number of BoZ builds. I always felt the B1 sounded better than the BoZs but the B1 has no gain and all my amps require a high gain preamp. In this case the single stage tube preamp will provide all the gain I require and now the ability to drive low impedance SS amps etc. images to follow.

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Projects: "Abstinence" - 6EM7 power amp | "Sanguine" - 6AS7 Headphone amp with Sophia Mesh Plate 274B rec. tube | "VoXDeuX65" - Inexpensive 2-Way Speakers ]
Website: [ retro-thermionic ]


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PostPosted: 08 Apr 2014, 00:16 
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Location: Australia
An image of the PS for HT and the B1 brds. It appears the box I was to use for the amp will not work so I'm going to use a 2U 19" rack enclosure.
Attachment:
Brds.jpg


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_________________
Projects: "Abstinence" - 6EM7 power amp | "Sanguine" - 6AS7 Headphone amp with Sophia Mesh Plate 274B rec. tube | "VoXDeuX65" - Inexpensive 2-Way Speakers ]
Website: [ retro-thermionic ]


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PostPosted: 10 Apr 2014, 02:18 
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Joined: 06 Jun 2008, 18:23
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Location: Australia
Two modules done and now to mark and drill the 2U enclosure. The modules are the rectifier module for the B1 and the 4S MKIII (The Black) tube section. I wanted to use the Solen 0.47uf caps I used in the original The Black but I'm out of them. So these Sprague Orange drops are my next choice but 0.47ufs are huge. Lucky this turret brds. (thanks Bruce) can easily accommodate these monsters. Progress is slow and the projects are mounting up. I'm up north next week so it will be a while before this project is complete.
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Brds_2.jpg


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_________________
Projects: "Abstinence" - 6EM7 power amp | "Sanguine" - 6AS7 Headphone amp with Sophia Mesh Plate 274B rec. tube | "VoXDeuX65" - Inexpensive 2-Way Speakers ]
Website: [ retro-thermionic ]


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