Hi,
New to the forum. Been wanting to do some audio DIY for over 15 years, and I'm finally taking time to do it. I've acquired parts over the years, including some nice caps. But, a primary thing I would like to do--besides making a nice-sounding amp--is use my hard-earned tube stash, which consists of some nice ECC82, EEC83, ECC88, EL34, and KT88 variants. (Also have some 6SN7's and 6V6GT's.)
The following schematic link is to a redraw of the Williamson 1949 amp by Keith Snook, who I will thank up front for his work, as clear schematics seem hard to come by. Thanks Keith!
http://www.keith-snook.info/amplifier-hifi-schematics/Williamson amplifier 1949.pdf
My question, of course, is can this circuit be made to use some combo of ECC82's and/or ECC83's with EL34 or KT88 output tubes in lieu of the ECC81's and KT66's? If so, can it be done without sacrificing sound quality? Or, should I be looking at another circuit? I don't have any transformers yet, so...
I'm self taught and can read basic tube specs and get the voltages into spec (I think), but I don't trust my ability to design circuits--yet. Any advice is appreciated.
Best,
Louis
New to the forum. Been wanting to do some audio DIY for over 15 years, and I'm finally taking time to do it. I've acquired parts over the years, including some nice caps. But, a primary thing I would like to do--besides making a nice-sounding amp--is use my hard-earned tube stash, which consists of some nice ECC82, EEC83, ECC88, EL34, and KT88 variants. (Also have some 6SN7's and 6V6GT's.)
The following schematic link is to a redraw of the Williamson 1949 amp by Keith Snook, who I will thank up front for his work, as clear schematics seem hard to come by. Thanks Keith!
http://www.keith-snook.info/amplifier-hifi-schematics/Williamson amplifier 1949.pdf
My question, of course, is can this circuit be made to use some combo of ECC82's and/or ECC83's with EL34 or KT88 output tubes in lieu of the ECC81's and KT66's? If so, can it be done without sacrificing sound quality? Or, should I be looking at another circuit? I don't have any transformers yet, so...
I'm self taught and can read basic tube specs and get the voltages into spec (I think), but I don't trust my ability to design circuits--yet. Any advice is appreciated.
Best,
Louis
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BTW, I'm not asking for someone to go through the linked schematic and work out what all of the values would have to be. I'm asking for two things:
1) For those of you with designing experience, is it obvious in some way that what I want to do doesn't make sense in this circuit--or does make sense and requires some value manipulation that should work fine?
2) Generally, where do I start with re-figuring the values that would make, say a 12AU7 and 12AX7 work? Just some general guidance on the process of modifying the circuit. I have the formulas and tube data for the most part. I just need a little help.
I'm not married to the Williamson 1949 circuit, BTW. If there is a nice-sounding circuit that does use the ECC82, ECC83, and/or ECC88 variants, along with EL34's or KT88's, then please direct me to such.
Thanks,
Louis
1) For those of you with designing experience, is it obvious in some way that what I want to do doesn't make sense in this circuit--or does make sense and requires some value manipulation that should work fine?
2) Generally, where do I start with re-figuring the values that would make, say a 12AU7 and 12AX7 work? Just some general guidance on the process of modifying the circuit. I have the formulas and tube data for the most part. I just need a little help.
I'm not married to the Williamson 1949 circuit, BTW. If there is a nice-sounding circuit that does use the ECC82, ECC83, and/or ECC88 variants, along with EL34's or KT88's, then please direct me to such.
Thanks,
Louis
Michaelson & Austin TVA-1. ECC83, ECC81, 2 x KT88 = 100 W p.ch. All of them still manufactured and easily to obtain. Fully symmetric design, LTP as the 1st stage. And yes, you might also re-design this amplifier for other tubes, such als EL34, 6L6GC etc. by choosing appropriate iron.
Best regards!
Best regards!
The 12AU7/ECC82 definitely can substitute for the 6SN7 in a Williamson style build. See the attached Heath W5M schematic.
Keep 2 things firmly in mind, before starting a build. 1: The triode inside 12AU7s is non-linear, while the triode in 6SN7s is very linear. Heavy reliance is placed on NFB to keep things orderly. The "plus" of the 'U7 is halved heater current draw. 2: The "Achilles Heel" of Williamson style topology is low frequency instability. Quality O/P transformers that exhibit minimal phase shifts are essential and that equates to $.
Keep 2 things firmly in mind, before starting a build. 1: The triode inside 12AU7s is non-linear, while the triode in 6SN7s is very linear. Heavy reliance is placed on NFB to keep things orderly. The "plus" of the 'U7 is halved heater current draw. 2: The "Achilles Heel" of Williamson style topology is low frequency instability. Quality O/P transformers that exhibit minimal phase shifts are essential and that equates to $.
Attachments
Thank you both! This is exactly the kind of information I need. I chose the Williamson 1949 from many, many schematics I've looked at for two reasons: 1) i could actually read it, thanks to Keith, and 2) it seemed (by my intuition) amenable to the substitutions I wanted to make. But, I had no further information about the general characteristics of the Williamson design.
I'll look into the TVA-1. Thank you.
Louis
I'll look into the TVA-1. Thank you.
Louis