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About xlr8or

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  1. Hi David. Please try what @Fruit recommended. Swap the middle 6SN7 for the one on the left or right and let us know what happens. The fact that all passive outputs (speakers/headphones) trialled give the same veiled sound suggests something is not right in the line regulation stage. You may be really unlucky and have a dud pair of 6SL7's. It may also help to open up the unit and take some close-up photos of the inside to confirm if any components may be wrong values in circuit. Again, highly unlikely but worth a shot.
  2. A lot of people may not know this but Mullard in the mid to late 1950's did manufacture a specific 6SN7GT in their Tottenham factory in the UK. These are also found as Tungsram England labelled tubes. Behold a grey smoked glass sample manufactured in May 1955.
  3. Lockdown in Sydney and in other parts of OZ is tough. But when the gas inside is in lockdown and can't escape my grasp then a showcase of beauty appears. A beautiful NOS pair of July 1942 Sylvania black plate metal base 7F7's that have come my way.
  4. That's more like the direction this thread should be headed. Thanks for sharing this lovely photo of some of the tubes I have recommended. It looks totally awesome. 👍 Please update us on your listening impressions in 100 hours.
  5. Can you share measured values for the heater, plate and grid voltages going to the EL34 for this single-tube full-wave configuration?
  6. This is how you get @muon* to come back into this thread. Rolling coupling caps in the R8. 🤣
  7. It's like comparing turning a wheel and see saw action against each other to draw in water from a pump. Both designs are different. One design requires more work than the other in pumping in the water. A one versus two person design. 🙂
  8. In my personal opinion I wouldn't recommend undertaking this mod as it defeats the purpose of buying the R8. Having said that though the mod is clever as it simplifies and shortens the signal path. If I was a DIYer and building my own amp I would definitely pursue this design. I have a parallel single ended design that uses 2 300B's in each monoblock. Removing one 300B and using just the one 300B has done wonders. An other thing to also be mindful of is the resale value and onselling the unit to others. It is easy to find on forums such as these what previous owners have been up to
  9. I was suggesting the 6J5 be used in place of 6SL7 or 6SN7 duty with the single EL34 configuration you have conjured up here. Something to think about with minimal circuit design change.
  10. I would recommend switching to the 6J5 if you are wanting to keep the single EL34 configuration.
  11. I'm ready to take the exam. I've watched the video 100 times already. 😁 Edit: Bugger it, I'll set the exam questions and answers instead. Q1: In what year and month did the Blackburn factory introduce the ECC83 as a noval 9-pin mini solution? A: May 1953 coded as 1600 E3 with 17mm black welded toasted anode plates, square goal post getter and wrinkled glass envelope construction. 🙄
  12. Apologies - I will rephrase. What is happening at the front end then with the 6SL7 and 6SN7 tubes. Is one triode now redundant?
  13. Is the octal front end using each triode to feed the EL34 PP pair?
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