Hi All although this kit has not been released by hificollective as of yet (it is due to be released at the end of April and there is a waiting list for orders) has anyone seen anything remotely in the same league as this?
http://www.hificollective.co.uk/kits/glasshousehome.html
any comments would be greatly appreciated
Cheers
Andrew
http://www.hificollective.co.uk/kits/glasshousehome.html
any comments would be greatly appreciated
Cheers
Andrew
Cool, open-source schenatics.
Interesting how they use a pentode into a cathode follower to drive a 300B, I thought those were a no-no? 😛
This amp is a heretic! 🙂
Interesting how they use a pentode into a cathode follower to drive a 300B, I thought those were a no-no? 😛
This amp is a heretic! 🙂
Hi Shifty,
Yes, perhaps the design is heretic.
There is a lot of hidden detail to it; indicates huge experience.
First, the EF86 pentode was used in some of the Leak and the Quad II. In this circuit, gain would be close on 45dB, so only one stage is required, not the usual three. Nothing wrong with pentodes in SE; good ones sound great. Another very good pentode, used by Pete Millett for driving an 813, is the 12HG7.
Second, a CF is fine if the right tube is chosen and the operating point carefully selected, usually by listening tests. A benefit is that biasing the output tube is easier since it takes place at the CF itself, and the warm-up cycle of the tubes is very well accommodated.
Thirdly, Grove is using a judicious combination of cathode bias and fixed bias. This is unusual, and shows considerable thought has gone into the design. Most 300Bs with cathode bias sound a little too fruity to me; this design would sharpen it up considerably.
This is, in my view, a very good design specifically designed for outstanding sonics. There is no evidence I can see of an overly mathematical or PSpice approach; the design is based on solid, empirical experience.
Cheers,
Hugh
Yes, perhaps the design is heretic.
There is a lot of hidden detail to it; indicates huge experience.
First, the EF86 pentode was used in some of the Leak and the Quad II. In this circuit, gain would be close on 45dB, so only one stage is required, not the usual three. Nothing wrong with pentodes in SE; good ones sound great. Another very good pentode, used by Pete Millett for driving an 813, is the 12HG7.
Second, a CF is fine if the right tube is chosen and the operating point carefully selected, usually by listening tests. A benefit is that biasing the output tube is easier since it takes place at the CF itself, and the warm-up cycle of the tubes is very well accommodated.
Thirdly, Grove is using a judicious combination of cathode bias and fixed bias. This is unusual, and shows considerable thought has gone into the design. Most 300Bs with cathode bias sound a little too fruity to me; this design would sharpen it up considerably.
This is, in my view, a very good design specifically designed for outstanding sonics. There is no evidence I can see of an overly mathematical or PSpice approach; the design is based on solid, empirical experience.
Cheers,
Hugh
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