Author Topic: Effectrode LA-1A tear-down and trace adventure  (Read 4820 times)

sonolink

Re: Effectrode LA-1A tear-down and trace adventure
« Reply #100 on: February 21, 2021, 02:58:45 PM »
Well that's certainly great news!!Thanks for the input. I'll come back if I need assistance with this project and your advices and experience will be very much appreciated. Thanks again!

Cheers
Sono

PRR

Re: Effectrode LA-1A tear-down and trace adventure
« Reply #101 on: February 21, 2021, 09:38:35 PM »
> are you saying that I can use a 9v.............with the heaters wired for 12v

Leave your car headlights on until the 12V battery runs down to 9V. The lights sure will still "work". Not at 100% design brightness. But most tube heaters are oversized, and most small-audio uses do not come close to the full cathode rating at nominal heater voltage. There are a couple commercial preamps that run heaters cool. Dynaco ran 11V on 12.6V heaters. Scott had a model where all the 12AX7 ran very low current and 9V heat was ample, arguably better.
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vigilante397

Re: Effectrode LA-1A tear-down and trace adventure
« Reply #102 on: February 21, 2021, 09:43:33 PM »
> are you saying that I can use a 9v.............with the heaters wired for 12v

Leave your car headlights on until the 12V battery runs down to 9V. The lights sure will still "work". Not at 100% design brightness. But most tube heaters are oversized, and most small-audio uses do not come close to the full cathode rating at nominal heater voltage. There are a couple commercial preamps that run heaters cool. Dynaco ran 11V on 12.6V heaters. Scott had a model where all the 12AX7 ran very low current and 9V heat was ample, arguably better.

And frankly that was a surprise for me. I mean I know Matsumin made it work, but all my Valvecaster builds had been a bit noisy at 9V.

I have a handful of 12AX7 preamp designs that I had planned to run at 12V, and people started asking me to design a way to run them at 9V or 12V. I was getting frustrated looking for a good regulator that could boost 9V to 12V efficiently but still accept a 12V input without problem, then one night I said screw it and just plugged my 1Spot into the preamp. Not only did it sound exactly the same (to my ears at least) it pulled slightly less current at 9V than it did at 12V. So I left the design as-is and started printing 9-12V on the enclosures.
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"I'm not sure what "serious design flaws" you see. Does it explode or poison your dog?" - PRR

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