Hornmiester Posted April 19, 2014 Share Posted April 19, 2014 I know there was a recent thread on a First Watt DYI build. Does anyone have experience with a First Watt / Pass Labs SIT-2 driving La Scalas of Klipshorns? How does it compare with a SET amp? Thoughts about sound stage, bass development, etc? As it is a ten watt amp, how well does it drive horn speakers? Quote Link to comment Share on other sites More sharing options...
Johnny's Jill Posted April 19, 2014 Share Posted April 19, 2014 I dont know about the sit2, but the daves f5 is killer. I suspect the SIT will be just as good. 10 watts is plenty of power for KHorns or Lascala. Craig Quote Link to comment Share on other sites More sharing options...
Guest David H Posted April 19, 2014 Share Posted April 19, 2014 This is from the DIY Audio website. Thought this might apply. Dave Nelson Pass The one and only Join Date: Mar 2001 You may not be able to name a favorite child, but a parent always has an opinion about the characteristics. I always keep in mind that someone else's experience will not duplicate mine. Speaking strictly of the the FW amplifiers, my listening is generally restricted to 90+ dB sensitivity and no tough loads, as the amps are low power and typically low damping factor. F5: Dynamic, accurate, a little unforgiving. On speakers with peaks in the top end, it will reveal as too bright and annoying. On speakers with a slightly diminished top end, it adds a little sparkle, this in spite of being flat out at high as 500 KHz. Good control - if your speaker is a little boomy, it will tend to tighten it up. Overall, probably the most neutral of the FW amps. It will drive 4 ohm loads without particular issues. Oh, and it does sound very good. J2: A more relaxed version of the F5. Decent bottom end control, a warm midrange, excellent depth. Overall, one of the most popular pieces. Still in production, it best hits the mainstream taste of the FW audience, probably because it delivers a consistently pleasant sound. Not intended for 4 ohms unless the speaker is particularly efficient, which is rare. F3: An even more relaxed version of the J2. Not much power or control. Popular with Avant Gardes and other horn drivers, and does smooth out the peaks in the tops of a lot of full range drivers. Used to be my favorite for the Feastrex and Lowthers over the F5, now has to compete with SIT-1 and SIT-2 for that spot. M2: Some people just like the sound of push-pull output stages, transformers and no feedback, and this is what the M2 delivers. Limited bandwidth and control, but a pleasant sound, and it will drive 4 ohms. Has a bit more noise than the other amps due to hum pickup on the input transformers, although nobody seems to mind very much. SIT-1: Broke the mold in the ability to play with the load line of a no-feedback Common Source amplifier that still has any damping factor. A very unique harmonic signature that can be dialed in to taste - Lots or little of 2nd harmonic of either phase. Literally the sound of one transistor clapping - without the input buffer (which no one seems to use) there is only 1 transistor in the amp. Has tremendous clarity and depth, depending on setting, spectral consistency with warmth and detail. It allows you to focus on a single instrument in an ensemble, almost to the exclusion of all else if you want. This is the amp that convinced me that absolute phase is not such a subtle factor. SIT-2: A SIT-1 with a constant current source load instead of a stack of power resistors. More efficient but similar to the SIT-1, it is set at a single load line setting, so is not quite as flexible or fun. Sony SIT amp (the big one shown at CES): This is a push pull VFET follower output stage. Dynamic, high power, good control, drives the crap out of 4 ohms. It was voiced around AR-1's, and shows them to good advantage. It is primarily 3rd harmonic in character, so the aspect is a little different than the single ended SIT designs, but it is very impressive, detailed and easy to listen to. You realize that the original VFET (SIT) designs from the 70's were not Class A and had more complex gain paths. I speculate that things might have turned out a little different if they had gone for simple Class A designs that play more to the strength of these parts. Of course tastes have changed over time. Quote Link to comment Share on other sites More sharing options...
eth2 Posted April 19, 2014 Share Posted April 19, 2014 This is from the DIY Audio website. Thought this might apply. Dave Nelson Pass The one and only Join Date: Mar 2001 You may not be able to name a favorite child, but a parent always has anopinion about the characteristics. I always keep in mind that someone else's experience will not duplicate mine. Speaking strictly of the the FW amplifiers, my listening is generally restricted to 90+ dB sensitivity and no tough loads, as the amps are low power and typically low damping factor. F5: Dynamic, accurate, a little unforgiving. On speakers with peaks in the top end, it will reveal as too bright and annoying. On speakers with a slightly diminished top end, it adds a little sparkle, this in spite of being flat out at high as 500 KHz. Good control - if your speaker is a little boomy, it will tend to tighten it up. Overall, probably the most neutral of the FW amps. It will drive 4 ohm loads without particular issues. Oh, and it does sound very good. J2: A more relaxed version of the F5. Decent bottom end control, a warm midrange, excellent depth. Overall, one of the most popular pieces. Still in production, it best hits the mainstream taste of the FW audience, probably because it delivers a consistently pleasant sound. Not intended for 4 ohms unless the speaker is particularly efficient, which is rare. F3: An even more relaxed version of the J2. Not much power or control. Popular with Avant Gardes and other horn drivers, and does smooth out the peaks in the tops of a lot of full range drivers. Used to be my favorite for the Feastrex and Lowthers over the F5, now has to compete with SIT-1 and SIT-2 for that spot. M2: Some people just like the sound of push-pull output stages, transformers and no feedback, and this is what the M2 delivers. Limited bandwidth and control, but a pleasant sound, and it will drive 4 ohms. Has a bit more noise than the other amps due to hum pickup on the input transformers, although nobody seems to mind very much. SIT-1: Broke the mold in the ability to play with the load line of a no-feedback Common Source amplifier that still has any damping factor. A very unique harmonic signature that can be dialed in to taste - Lots or little of 2nd harmonic of either phase. Literally the sound of one transistor clapping - without the input buffer (which no one seems to use) there is only 1 transistor in the amp. Has tremendous clarity and depth, depending on setting, spectral consistency with warmth and detail. It allows you to focus on a single instrument in an ensemble, almost to the exclusion of all else if you want. This is the amp that convinced me that absolute phase is not such a subtle factor. SIT-2: A SIT-1 with a constant current source load instead of a stack of power resistors. More efficient but similar to the SIT-1, it is set at a single load line setting, so is not quite as flexible or fun. Sony SIT amp (the big one shown at CES): This is a push pull VFET follower output stage. Dynamic, high power, good control, drives the crap out of 4 ohms. It was voiced around AR-1's, and shows them to good advantage. It is primarily 3rd harmonic in character, so the aspect is a little different than the single ended SIT designs, but it is very impressive, detailed and easy to listen to. You realize that the original VFET (SIT) designs from the 70's were not Class A and had more complex gain paths. I speculate that things might have turned out a little different if they had gone for simple Class A designs that play more to the strength of these parts. Of course tastes have changed over time. WOW! If you have not done professional reviews, you should consider a career change. Quote Link to comment Share on other sites More sharing options...
Guest David H Posted April 19, 2014 Share Posted April 19, 2014 WOW! If you have not done professional reviews, you should consider a career change. The quote in question was from the First Watts designer Nelson Pass. Dave Quote Link to comment Share on other sites More sharing options...
eth2 Posted April 19, 2014 Share Posted April 19, 2014 WOW! If you have not done professional reviews, you should consider a career change. The quote in question was from the First Watts designer Nelson Pass. Dave Well don't I feel like a horse's arse! Quote Link to comment Share on other sites More sharing options...
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