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Hi Alan,
That must've made a big difference!:)Quote:
Originally Posted by Firebottle
However, I'm not sure exactly what purpose/effect was intended by the latter, or why it would be considered as an upgrade. 6SL7s are superb valves for a line or phono stage. Could you elucidate on your thinking there, please?
Ta:cool:
Marco.
The heater circuit re-configuration was needed because there are 5 valves in the circuit.
All are 6.3V heaters fed from a regulated 12V supply, so valves are wired in twin series pairs.
The 5th valve is padded with a resistor to accommodate the 'spare 6V', this resistor is chosen for a 300mA heater current and is on one of the line stage valves.
The other line stage valve shares its circuit with one of the phono section valves.
Andy fitted alternative valves with a 600mA heater rating and discovered that he needed to fit 3 valves to make the line section only work, because of the shared heater circuit with part of the phono section.
The other line valve was underdriven because the resistor value was too high a value for the 600mA rating, causing this channel to be low on gain and distorted.
I rewired it so the two line valves were a series pair and could be fitted with 300 or 600mA rated valves, also only needing 2 valves to be fitted for line stage only operation.
Thanks for that, Alan. Makes sense:)
Do you know which "alternative valves" Andy fitted, and why? Not sure why he'd want to use anything other than 6SL7s - and any 6SL7 (or equivalent) works perfectly in my Croft, without the need for any adjustments, including RCA 5691 red base, VT229, Russian 6H9C, etc.
Marco.
No. But what a cool name. I bet if you met here you'd lurve her!;)Quote:
Originally Posted by Beobloke
Oh, you do!:D
mercedes?
Funnily enough, 6 of us were driven to the airport a few years back in an airport taxi minibus driven by a (smoking hot) young lady whose name genuinely was Mercedes. She explained that her dad was a car nut and that her mother finally capitulated and allowed him to use a car name on the youngest when she was born.
And in case you were wondering what minibus she was driving us in. That’s right; you guessed it!
It was a Transit Tourneo...
I'm in the market for a new cart and have been looking at Decca's and SPU's. This talk about the SC35C has piqued my interest, I've been going the idler/heavy arm/ low compliance route for a while. Stylus and body on the way!Quote:
Originally Posted by Marco
Can't remember, you'll have to ask Andy. Just trying alternatives I think.Quote:
Originally Posted by Marco
Nice one, Charlie. Glad to be of assistance and hope you like it! Did you manage to source an original 'Made in USA' body and NOS Shure stylus (with white writing on the front)? Those are the real deal!:)Quote:
Originally Posted by Chas B
Marco.
No worries, Alan. Hopefully, Andy will clarify later.Quote:
Originally Posted by Firebottle
Marco.