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SET and PSET with 6S33S
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Posted on May 5, 2015 at 10:30:22 | ||
Posts: 25
Location: Seattle Joined: June 4, 2009 |
Hi, A year ago I was greatly intrigued by the Melquiades 6S33S amp http://www.goodsoundclub.com/PDF/Melquiades_SET.pdf . I could not find much information outside of the Romy's website, so I decided to build and try it. It took me a lot of time, but finally I built it with LL1693 OPT and I want to share my experience. I am not very good at describing sound. However, I like the sound a lot and I consider myself demanding. I much prefer it to my RM-10 or really any amp I heard to date. Melquiades produces a very well defined sound, good bass, reproduces various genres very well, brings up texture and highlighting sound of acoustic instruments. It's easy to listen to and not fatiguing. I experimented a lot. I built SET as per Romy's design and PSET with 2x6S33S. I slightly prefer SET version to PSET, however, PSET gives some extra power which might come handy with my Meadowlark Hot Rod speakers. So I decided to build the final version in a way to easily switch from SET to PSET. It's actually quite simple with this amp. I tried various operating points for 6S33S and I was surprised how much sound changed with changing B+ from 210V to 180V. To my ears it's a bit harsh and 'transistory' at 210V and mellow at 180V. I think my preference is somewhere around 190V. Moving it from 200mA to 300mA also changes the sound (not dramatically though) making the amp sound a bit more confident at 300mA. I am debating trying a regulated power supply for 6S33S and I am looking for your advices on what other modifications I can try before I build an enclosure. |
RE: SET and PSET with 6S33S, posted on May 7, 2015 at 12:30:03 | |
Posts: 8313
Location: Seattle Joined: June 18, 2004 |
Actually, the bias will pop up by about a volt, which is not insignificant. |
RE: SET and PSET with 6S33S, posted on May 7, 2015 at 12:44:38 | |
Posts: 25
Location: Seattle Joined: June 4, 2009 |
Can you please explain how the bias can pop up? |
RE: Four Cree Schottky Diodes in Series, posted on May 7, 2015 at 16:34:04 | |
Posts: 25
Location: Seattle Joined: June 4, 2009 |
Interesting! Do you have a cap on the input? A schematic would be helpful. |
Schematic Enclosed, posted on May 7, 2015 at 18:00:18 | |
Posts: 856
Location: New Jersey Joined: May 26, 2006 |
No cap on the input. Not even a cap between the stages or in the cathode of the power tube.
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RE: Schematic Enclosed, posted on May 7, 2015 at 18:06:56 | |
Posts: 25
Location: Seattle Joined: June 4, 2009 |
Speechless! :-) I bet it sounds wonderful! Thank you for sharing. |
RE: SET and PSET with 6S33S, posted on May 7, 2015 at 19:10:37 | |
Posts: 8313
Location: Seattle Joined: June 18, 2004 |
Run the numbers for bias voltage assuming the input is shorted. |